Merge tag 'docs-4.10-2' of git://git.lwn.net/linux

Pull more documentation updates from Jonathan Corbet:
 "This converts the crypto DocBook to Sphinx"

* tag 'docs-4.10-2' of git://git.lwn.net/linux:
  crypto: doc - optimize compilation
  crypto: doc - clarify AEAD memory structure
  crypto: doc - remove crypto_alloc_ablkcipher
  crypto: doc - add KPP documentation
  crypto: doc - fix separation of cipher / req API
  crypto: doc - fix source comments for Sphinx
  crypto: doc - remove crypto API DocBook
  crypto: doc - convert crypto API documentation to Sphinx

Documentation/DocBook/Makefile

@@ -13,7 +13,7 @@ DOCBOOKS := z8530book.xml  \
 	    gadget.xml libata.xml mtdnand.xml librs.xml rapidio.xml \
 	    genericirq.xml s390-drivers.xml uio-howto.xml scsi.xml \
 	    80211.xml sh.xml regulator.xml w1.xml \
-	    writing_musb_glue_layer.xml crypto-API.xml iio.xml
+	    writing_musb_glue_layer.xml iio.xml
 
 ifeq ($(DOCBOOKS),)
 

Documentation/DocBook/crypto-API.tmpl

@@ -1,2092 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
-	"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
-
-<book id="KernelCryptoAPI">
- <bookinfo>
-  <title>Linux Kernel Crypto API</title>
-
-  <authorgroup>
-   <author>
-    <firstname>Stephan</firstname>
-    <surname>Mueller</surname>
-    <affiliation>
-     <address>
-      <email>smueller@chronox.de</email>
-     </address>
-    </affiliation>
-   </author>
-   <author>
-    <firstname>Marek</firstname>
-    <surname>Vasut</surname>
-    <affiliation>
-     <address>
-      <email>marek@denx.de</email>
-     </address>
-    </affiliation>
-   </author>
-  </authorgroup>
-
-  <copyright>
-   <year>2014</year>
-   <holder>Stephan Mueller</holder>
-  </copyright>
-
-
-  <legalnotice>
-   <para>
-     This documentation is free software; you can redistribute
-     it and/or modify it under the terms of the GNU General Public
-     License as published by the Free Software Foundation; either
-     version 2 of the License, or (at your option) any later
-     version.
-   </para>
-
-   <para>
-     This program is distributed in the hope that it will be
-     useful, but WITHOUT ANY WARRANTY; without even the implied
-     warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-     See the GNU General Public License for more details.
-   </para>
-
-   <para>
-     You should have received a copy of the GNU General Public
-     License along with this program; if not, write to the Free
-     Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
-     MA 02111-1307 USA
-   </para>
-
-   <para>
-     For more details see the file COPYING in the source
-     distribution of Linux.
-   </para>
-  </legalnotice>
- </bookinfo>
-
- <toc></toc>
-
- <chapter id="Intro">
-  <title>Kernel Crypto API Interface Specification</title>
-
-   <sect1><title>Introduction</title>
-
-    <para>
-     The kernel crypto API offers a rich set of cryptographic ciphers as
-     well as other data transformation mechanisms and methods to invoke
-     these. This document contains a description of the API and provides
-     example code.
-    </para>
-
-    <para>
-     To understand and properly use the kernel crypto API a brief
-     explanation of its structure is given. Based on the architecture,
-     the API can be separated into different components. Following the
-     architecture specification, hints to developers of ciphers are
-     provided. Pointers to the API function call  documentation are
-     given at the end.
-    </para>
-
-    <para>
-     The kernel crypto API refers to all algorithms as "transformations".
-     Therefore, a cipher handle variable usually has the name "tfm".
-     Besides cryptographic operations, the kernel crypto API also knows
-     compression transformations and handles them the same way as ciphers.
-    </para>
-
-    <para>
-     The kernel crypto API serves the following entity types:
-
-     <itemizedlist>
-      <listitem>
-       <para>consumers requesting cryptographic services</para>
-      </listitem>
-      <listitem>
-      <para>data transformation implementations (typically ciphers)
-       that can be called by consumers using the kernel crypto
-       API</para>
-      </listitem>
-     </itemizedlist>
-    </para>
-
-    <para>
-     This specification is intended for consumers of the kernel crypto
-     API as well as for developers implementing ciphers. This API
-     specification, however, does not discuss all API calls available
-     to data transformation implementations (i.e. implementations of
-     ciphers and other transformations (such as CRC or even compression
-     algorithms) that can register with the kernel crypto API).
-    </para>
-
-    <para>
-     Note: The terms "transformation" and cipher algorithm are used
-     interchangeably.
-    </para>
-   </sect1>
-
-   <sect1><title>Terminology</title>
-    <para>
-     The transformation implementation is an actual code or interface
-     to hardware which implements a certain transformation with precisely
-     defined behavior.
-    </para>
-
-    <para>
-     The transformation object (TFM) is an instance of a transformation
-     implementation. There can be multiple transformation objects
-     associated with a single transformation implementation. Each of
-     those transformation objects is held by a crypto API consumer or
-     another transformation. Transformation object is allocated when a
-     crypto API consumer requests a transformation implementation.
-     The consumer is then provided with a structure, which contains
-     a transformation object (TFM).
-    </para>
-
-    <para>
-     The structure that contains transformation objects may also be
-     referred to as a "cipher handle". Such a cipher handle is always
-     subject to the following phases that are reflected in the API calls
-     applicable to such a cipher handle:
-    </para>
-
-    <orderedlist>
-     <listitem>
-      <para>Initialization of a cipher handle.</para>
-     </listitem>
-     <listitem>
-      <para>Execution of all intended cipher operations applicable
-      for the handle where the cipher handle must be furnished to
-      every API call.</para>
-     </listitem>
-     <listitem>
-      <para>Destruction of a cipher handle.</para>
-     </listitem>
-    </orderedlist>
-
-    <para>
-     When using the initialization API calls, a cipher handle is
-     created and returned to the consumer. Therefore, please refer
-     to all initialization API calls that refer to the data
-     structure type a consumer is expected to receive and subsequently
-     to use. The initialization API calls have all the same naming
-     conventions of crypto_alloc_*.
-    </para>
-
-    <para>
-     The transformation context is private data associated with
-     the transformation object.
-    </para>
-   </sect1>
-  </chapter>
-
-  <chapter id="Architecture"><title>Kernel Crypto API Architecture</title>
-   <sect1><title>Cipher algorithm types</title>
-    <para>
-     The kernel crypto API provides different API calls for the
-     following cipher types:
-
-     <itemizedlist>
-      <listitem><para>Symmetric ciphers</para></listitem>
-      <listitem><para>AEAD ciphers</para></listitem>
-      <listitem><para>Message digest, including keyed message digest</para></listitem>
-      <listitem><para>Random number generation</para></listitem>
-      <listitem><para>User space interface</para></listitem>
-     </itemizedlist>
-    </para>
-   </sect1>
-
-   <sect1><title>Ciphers And Templates</title>
-    <para>
-     The kernel crypto API provides implementations of single block
-     ciphers and message digests. In addition, the kernel crypto API
-     provides numerous "templates" that can be used in conjunction
-     with the single block ciphers and message digests. Templates
-     include all types of block chaining mode, the HMAC mechanism, etc.
-    </para>
-
-    <para>
-     Single block ciphers and message digests can either be directly
-     used by a caller or invoked together with a template to form
-     multi-block ciphers or keyed message digests.
-    </para>
-
-    <para>
-     A single block cipher may even be called with multiple templates.
-     However, templates cannot be used without a single cipher.
-    </para>
-
-    <para>
-     See /proc/crypto and search for "name". For example:
-
-     <itemizedlist>
-      <listitem><para>aes</para></listitem>
-      <listitem><para>ecb(aes)</para></listitem>
-      <listitem><para>cmac(aes)</para></listitem>
-      <listitem><para>ccm(aes)</para></listitem>
-      <listitem><para>rfc4106(gcm(aes))</para></listitem>
-      <listitem><para>sha1</para></listitem>
-      <listitem><para>hmac(sha1)</para></listitem>
-      <listitem><para>authenc(hmac(sha1),cbc(aes))</para></listitem>
-     </itemizedlist>
-    </para>
-
-    <para>
-     In these examples, "aes" and "sha1" are the ciphers and all
-     others are the templates.
-    </para>
-   </sect1>
-
-   <sect1><title>Synchronous And Asynchronous Operation</title>
-    <para>
-     The kernel crypto API provides synchronous and asynchronous
-     API operations.
-    </para>
-
-    <para>
-     When using the synchronous API operation, the caller invokes
-     a cipher operation which is performed synchronously by the
-     kernel crypto API. That means, the caller waits until the
-     cipher operation completes. Therefore, the kernel crypto API
-     calls work like regular function calls. For synchronous
-     operation, the set of API calls is small and conceptually
-     similar to any other crypto library.
-    </para>
-
-    <para>
-     Asynchronous operation is provided by the kernel crypto API
-     which implies that the invocation of a cipher operation will
-     complete almost instantly. That invocation triggers the
-     cipher operation but it does not signal its completion. Before
-     invoking a cipher operation, the caller must provide a callback
-     function the kernel crypto API can invoke to signal the
-     completion of the cipher operation. Furthermore, the caller
-     must ensure it can handle such asynchronous events by applying
-     appropriate locking around its data. The kernel crypto API
-     does not perform any special serialization operation to protect
-     the caller's data integrity.
-    </para>
-   </sect1>
-
-   <sect1><title>Crypto API Cipher References And Priority</title>
-    <para>
-     A cipher is referenced by the caller with a string. That string
-     has the following semantics:
-
-     <programlisting>
-	template(single block cipher)
-     </programlisting>
-
-     where "template" and "single block cipher" is the aforementioned
-     template and single block cipher, respectively. If applicable,
-     additional templates may enclose other templates, such as
-
-      <programlisting>
-	template1(template2(single block cipher)))
-      </programlisting>
-    </para>
-
-    <para>
-     The kernel crypto API may provide multiple implementations of a
-     template or a single block cipher. For example, AES on newer
-     Intel hardware has the following implementations: AES-NI,
-     assembler implementation, or straight C. Now, when using the
-     string "aes" with the kernel crypto API, which cipher
-     implementation is used? The answer to that question is the
-     priority number assigned to each cipher implementation by the
-     kernel crypto API. When a caller uses the string to refer to a
-     cipher during initialization of a cipher handle, the kernel
-     crypto API looks up all implementations providing an
-     implementation with that name and selects the implementation
-     with the highest priority.
-    </para>
-
-    <para>
-     Now, a caller may have the need to refer to a specific cipher
-     implementation and thus does not want to rely on the
-     priority-based selection. To accommodate this scenario, the
-     kernel crypto API allows the cipher implementation to register
-     a unique name in addition to common names. When using that
-     unique name, a caller is therefore always sure to refer to
-     the intended cipher implementation.
-    </para>
-
-    <para>
-     The list of available ciphers is given in /proc/crypto. However,
-     that list does not specify all possible permutations of
-     templates and ciphers. Each block listed in /proc/crypto may
-     contain the following information -- if one of the components
-     listed as follows are not applicable to a cipher, it is not
-     displayed:
-    </para>
-
-    <itemizedlist>
-     <listitem>
-      <para>name: the generic name of the cipher that is subject
-       to the priority-based selection -- this name can be used by
-       the cipher allocation API calls (all names listed above are
-       examples for such generic names)</para>
-     </listitem>
-     <listitem>
-      <para>driver: the unique name of the cipher -- this name can
-       be used by the cipher allocation API calls</para>
-     </listitem>
-     <listitem>
-      <para>module: the kernel module providing the cipher
-       implementation (or "kernel" for statically linked ciphers)</para>
-     </listitem>
-     <listitem>
-      <para>priority: the priority value of the cipher implementation</para>
-     </listitem>
-     <listitem>
-      <para>refcnt: the reference count of the respective cipher
-       (i.e. the number of current consumers of this cipher)</para>
-     </listitem>
-     <listitem>
-      <para>selftest: specification whether the self test for the
-       cipher passed</para>
-     </listitem>
-     <listitem>
-      <para>type:
-       <itemizedlist>
-        <listitem>
-         <para>skcipher for symmetric key ciphers</para>
-        </listitem>
-        <listitem>
-         <para>cipher for single block ciphers that may be used with
-          an additional template</para>
-        </listitem>
-        <listitem>
-         <para>shash for synchronous message digest</para>
-        </listitem>
-        <listitem>
-         <para>ahash for asynchronous message digest</para>
-        </listitem>
-        <listitem>
-         <para>aead for AEAD cipher type</para>
-        </listitem>
-        <listitem>
-         <para>compression for compression type transformations</para>
-        </listitem>
-        <listitem>
-         <para>rng for random number generator</para>
-        </listitem>
-        <listitem>
-         <para>givcipher for cipher with associated IV generator
-          (see the geniv entry below for the specification of the
-          IV generator type used by the cipher implementation)</para>
-        </listitem>
-       </itemizedlist>
-      </para>
-     </listitem>
-     <listitem>
-      <para>blocksize: blocksize of cipher in bytes</para>
-     </listitem>
-     <listitem>
-      <para>keysize: key size in bytes</para>
-     </listitem>
-     <listitem>
-      <para>ivsize: IV size in bytes</para>
-     </listitem>
-     <listitem>
-      <para>seedsize: required size of seed data for random number
-       generator</para>
-     </listitem>
-     <listitem>
-      <para>digestsize: output size of the message digest</para>
-     </listitem>
-     <listitem>
-      <para>geniv: IV generation type:
-       <itemizedlist>
-        <listitem>
-         <para>eseqiv for encrypted sequence number based IV
-          generation</para>
-        </listitem>
-        <listitem>
-         <para>seqiv for sequence number based IV generation</para>
-        </listitem>
-        <listitem>
-         <para>chainiv for chain iv generation</para>
-        </listitem>
-        <listitem>
-         <para>&lt;builtin&gt; is a marker that the cipher implements
-          IV generation and handling as it is specific to the given
-          cipher</para>
-        </listitem>
-       </itemizedlist>
-      </para>
-     </listitem>
-    </itemizedlist>
-   </sect1>
-
-   <sect1><title>Key Sizes</title>
-    <para>
-     When allocating a cipher handle, the caller only specifies the
-     cipher type. Symmetric ciphers, however, typically support
-     multiple key sizes (e.g. AES-128 vs. AES-192 vs. AES-256).
-     These key sizes are determined with the length of the provided
-     key. Thus, the kernel crypto API does not provide a separate
-     way to select the particular symmetric cipher key size.
-    </para>
-   </sect1>
-
-   <sect1><title>Cipher Allocation Type And Masks</title>
-    <para>
-     The different cipher handle allocation functions allow the
-     specification of a type and mask flag. Both parameters have
-     the following meaning (and are therefore not covered in the
-     subsequent sections).
-    </para>
-
-    <para>
-     The type flag specifies the type of the cipher algorithm.
-     The caller usually provides a 0 when the caller wants the
-     default handling. Otherwise, the caller may provide the
-     following selections which match the aforementioned cipher
-     types:
-    </para>
-
-    <itemizedlist>
-     <listitem>
-      <para>CRYPTO_ALG_TYPE_CIPHER Single block cipher</para>
-     </listitem>
-     <listitem>
-      <para>CRYPTO_ALG_TYPE_COMPRESS Compression</para>
-     </listitem>
-     <listitem>
-     <para>CRYPTO_ALG_TYPE_AEAD Authenticated Encryption with
-      Associated Data (MAC)</para>
-     </listitem>
-     <listitem>
-      <para>CRYPTO_ALG_TYPE_BLKCIPHER Synchronous multi-block cipher</para>
-     </listitem>
-     <listitem>
-      <para>CRYPTO_ALG_TYPE_ABLKCIPHER Asynchronous multi-block cipher</para>
-     </listitem>
-     <listitem>
-      <para>CRYPTO_ALG_TYPE_GIVCIPHER Asynchronous multi-block
-       cipher packed together with an IV generator (see geniv field
-       in the /proc/crypto listing for the known IV generators)</para>
-     </listitem>
-     <listitem>
-      <para>CRYPTO_ALG_TYPE_DIGEST Raw message digest</para>
-     </listitem>
-     <listitem>
-      <para>CRYPTO_ALG_TYPE_HASH Alias for CRYPTO_ALG_TYPE_DIGEST</para>
-     </listitem>
-     <listitem>
-      <para>CRYPTO_ALG_TYPE_SHASH Synchronous multi-block hash</para>
-     </listitem>
-     <listitem>
-      <para>CRYPTO_ALG_TYPE_AHASH Asynchronous multi-block hash</para>
-     </listitem>
-     <listitem>
-      <para>CRYPTO_ALG_TYPE_RNG Random Number Generation</para>
-     </listitem>
-     <listitem>
-      <para>CRYPTO_ALG_TYPE_AKCIPHER Asymmetric cipher</para>
-     </listitem>
-     <listitem>
-      <para>CRYPTO_ALG_TYPE_PCOMPRESS Enhanced version of
-       CRYPTO_ALG_TYPE_COMPRESS allowing for segmented compression /
-       decompression instead of performing the operation on one
-       segment only. CRYPTO_ALG_TYPE_PCOMPRESS is intended to replace
-       CRYPTO_ALG_TYPE_COMPRESS once existing consumers are converted.</para>
-     </listitem>
-    </itemizedlist>
-
-    <para>
-     The mask flag restricts the type of cipher. The only allowed
-     flag is CRYPTO_ALG_ASYNC to restrict the cipher lookup function
-     to asynchronous ciphers. Usually, a caller provides a 0 for the
-     mask flag.
-    </para>
-
-    <para>
-     When the caller provides a mask and type specification, the
-     caller limits the search the kernel crypto API can perform for
-     a suitable cipher implementation for the given cipher name.
-     That means, even when a caller uses a cipher name that exists
-     during its initialization call, the kernel crypto API may not
-     select it due to the used type and mask field.
-    </para>
-   </sect1>
-
-   <sect1><title>Internal Structure of Kernel Crypto API</title>
-
-    <para>
-     The kernel crypto API has an internal structure where a cipher
-     implementation may use many layers and indirections. This section
-     shall help to clarify how the kernel crypto API uses
-     various components to implement the complete cipher.
-    </para>
-
-    <para>
-     The following subsections explain the internal structure based
-     on existing cipher implementations. The first section addresses
-     the most complex scenario where all other scenarios form a logical
-     subset.
-    </para>
-
-    <sect2><title>Generic AEAD Cipher Structure</title>
-
-     <para>
-      The following ASCII art decomposes the kernel crypto API layers
-      when using the AEAD cipher with the automated IV generation. The
-      shown example is used by the IPSEC layer.
-     </para>
-
-     <para>
-      For other use cases of AEAD ciphers, the ASCII art applies as
-      well, but the caller may not use the AEAD cipher with a separate
-      IV generator. In this case, the caller must generate the IV.
-     </para>
-
-     <para>
-      The depicted example decomposes the AEAD cipher of GCM(AES) based
-      on the generic C implementations (gcm.c, aes-generic.c, ctr.c,
-      ghash-generic.c, seqiv.c). The generic implementation serves as an
-      example showing the complete logic of the kernel crypto API.
-     </para>
-
-     <para>
-      It is possible that some streamlined cipher implementations (like
-      AES-NI) provide implementations merging aspects which in the view
-      of the kernel crypto API cannot be decomposed into layers any more.
-      In case of the AES-NI implementation, the CTR mode, the GHASH
-      implementation and the AES cipher are all merged into one cipher
-      implementation registered with the kernel crypto API. In this case,
-      the concept described by the following ASCII art applies too. However,
-      the decomposition of GCM into the individual sub-components
-      by the kernel crypto API is not done any more.
-     </para>
-
-     <para>
-      Each block in the following ASCII art is an independent cipher
-      instance obtained from the kernel crypto API. Each block
-      is accessed by the caller or by other blocks using the API functions
-      defined by the kernel crypto API for the cipher implementation type.
-     </para>
-
-     <para>
-      The blocks below indicate the cipher type as well as the specific
-      logic implemented in the cipher.
-     </para>
-
-     <para>
-      The ASCII art picture also indicates the call structure, i.e. who
-      calls which component. The arrows point to the invoked block
-      where the caller uses the API applicable to the cipher type
-      specified for the block.
-     </para>
-
-     <programlisting>
-<![CDATA[
-kernel crypto API                                |   IPSEC Layer
-                                                 |
-+-----------+                                    |
-|           |            (1)
-|   aead    | <-----------------------------------  esp_output
-|  (seqiv)  | ---+
-+-----------+    |
-                 | (2)
-+-----------+    |
-|           | <--+                (2)
-|   aead    | <-----------------------------------  esp_input
-|   (gcm)   | ------------+
-+-----------+             |
-      | (3)               | (5)
-      v                   v
-+-----------+       +-----------+
-|           |       |           |
-|  skcipher |       |   ahash   |
-|   (ctr)   | ---+  |  (ghash)  |
-+-----------+    |  +-----------+
-                 |
-+-----------+    | (4)
-|           | <--+
-|   cipher  |
-|   (aes)   |
-+-----------+
-]]>
-     </programlisting>
-
-     <para>
-      The following call sequence is applicable when the IPSEC layer
-      triggers an encryption operation with the esp_output function. During
-      configuration, the administrator set up the use of rfc4106(gcm(aes)) as
-      the cipher for ESP. The following call sequence is now depicted in the
-      ASCII art above:
-     </para>
-
-     <orderedlist>
-      <listitem>
-       <para>
-        esp_output() invokes crypto_aead_encrypt() to trigger an encryption
-        operation of the AEAD cipher with IV generator.
-       </para>
-
-       <para>
-        In case of GCM, the SEQIV implementation is registered as GIVCIPHER
-        in crypto_rfc4106_alloc().
-       </para>
-
-       <para>
-        The SEQIV performs its operation to generate an IV where the core
-        function is seqiv_geniv().
-       </para>
-      </listitem>
-
-      <listitem>
-       <para>
-        Now, SEQIV uses the AEAD API function calls to invoke the associated
-        AEAD cipher. In our case, during the instantiation of SEQIV, the
-        cipher handle for GCM is provided to SEQIV. This means that SEQIV
-        invokes AEAD cipher operations with the GCM cipher handle.
-       </para>
-
-       <para>
-        During instantiation of the GCM handle, the CTR(AES) and GHASH
-        ciphers are instantiated. The cipher handles for CTR(AES) and GHASH
-        are retained for later use.
-       </para>
-
-       <para>
-        The GCM implementation is responsible to invoke the CTR mode AES and
-        the GHASH cipher in the right manner to implement the GCM
-        specification.
-       </para>
-      </listitem>
-
-      <listitem>
-       <para>
-        The GCM AEAD cipher type implementation now invokes the SKCIPHER API
-        with the instantiated CTR(AES) cipher handle.
-       </para>
-
-       <para>
-	During instantiation of the CTR(AES) cipher, the CIPHER type
-	implementation of AES is instantiated. The cipher handle for AES is
-	retained.
-       </para>
-
-       <para>
-        That means that the SKCIPHER implementation of CTR(AES) only
-        implements the CTR block chaining mode. After performing the block
-        chaining operation, the CIPHER implementation of AES is invoked.
-       </para>
-      </listitem>
-
-      <listitem>
-       <para>
-        The SKCIPHER of CTR(AES) now invokes the CIPHER API with the AES
-        cipher handle to encrypt one block.
-       </para>
-      </listitem>
-
-      <listitem>
-       <para>
-        The GCM AEAD implementation also invokes the GHASH cipher
-        implementation via the AHASH API.
-       </para>
-      </listitem>
-     </orderedlist>
-
-     <para>
-      When the IPSEC layer triggers the esp_input() function, the same call
-      sequence is followed with the only difference that the operation starts
-      with step (2).
-     </para>
-    </sect2>
-
-    <sect2><title>Generic Block Cipher Structure</title>
-     <para>
-      Generic block ciphers follow the same concept as depicted with the ASCII
-      art picture above.
-     </para>
-
-     <para>
-      For example, CBC(AES) is implemented with cbc.c, and aes-generic.c. The
-      ASCII art picture above applies as well with the difference that only
-      step (4) is used and the SKCIPHER block chaining mode is CBC.
-     </para>
-    </sect2>
-
-    <sect2><title>Generic Keyed Message Digest Structure</title>
-     <para>
-      Keyed message digest implementations again follow the same concept as
-      depicted in the ASCII art picture above.
-     </para>
-
-     <para>
-      For example, HMAC(SHA256) is implemented with hmac.c and
-      sha256_generic.c. The following ASCII art illustrates the
-      implementation:
-     </para>
-
-     <programlisting>
-<![CDATA[
-kernel crypto API            |       Caller
-                             |
-+-----------+         (1)    |
-|           | <------------------  some_function
-|   ahash   |
-|   (hmac)  | ---+
-+-----------+    |
-                 | (2)
-+-----------+    |
-|           | <--+
-|   shash   |
-|  (sha256) |
-+-----------+
-]]>
-     </programlisting>
-
-     <para>
-      The following call sequence is applicable when a caller triggers
-      an HMAC operation:
-     </para>
-
-     <orderedlist>
-      <listitem>
-       <para>
-        The AHASH API functions are invoked by the caller. The HMAC
-        implementation performs its operation as needed.
-       </para>
-
-       <para>
-        During initialization of the HMAC cipher, the SHASH cipher type of
-        SHA256 is instantiated. The cipher handle for the SHA256 instance is
-        retained.
-       </para>
-
-       <para>
-        At one time, the HMAC implementation requires a SHA256 operation
-        where the SHA256 cipher handle is used.
-       </para>
-      </listitem>
-
-      <listitem>
-       <para>
-        The HMAC instance now invokes the SHASH API with the SHA256
-        cipher handle to calculate the message digest.
-       </para>
-      </listitem>
-     </orderedlist>
-    </sect2>
-   </sect1>
-  </chapter>
-
-  <chapter id="Development"><title>Developing Cipher Algorithms</title>
-   <sect1><title>Registering And Unregistering Transformation</title>
-    <para>
-     There are three distinct types of registration functions in
-     the Crypto API. One is used to register a generic cryptographic
-     transformation, while the other two are specific to HASH
-     transformations and COMPRESSion. We will discuss the latter
-     two in a separate chapter, here we will only look at the
-     generic ones.
-    </para>
-
-    <para>
-     Before discussing the register functions, the data structure
-     to be filled with each, struct crypto_alg, must be considered
-     -- see below for a description of this data structure.
-    </para>
-
-    <para>
-     The generic registration functions can be found in
-     include/linux/crypto.h and their definition can be seen below.
-     The former function registers a single transformation, while
-     the latter works on an array of transformation descriptions.
-     The latter is useful when registering transformations in bulk,
-     for example when a driver implements multiple transformations.
-    </para>
-
-    <programlisting>
-   int crypto_register_alg(struct crypto_alg *alg);
-   int crypto_register_algs(struct crypto_alg *algs, int count);
-    </programlisting>
-
-    <para>
-     The counterparts to those functions are listed below.
-    </para>
-
-    <programlisting>
-   int crypto_unregister_alg(struct crypto_alg *alg);
-   int crypto_unregister_algs(struct crypto_alg *algs, int count);
-    </programlisting>
-
-    <para>
-     Notice that both registration and unregistration functions
-     do return a value, so make sure to handle errors. A return
-     code of zero implies success. Any return code &lt; 0 implies
-     an error.
-    </para>
-
-    <para>
-     The bulk registration/unregistration functions
-     register/unregister each transformation in the given array of
-     length count.  They handle errors as follows:
-    </para>
-    <itemizedlist>
-     <listitem>
-      <para>
-       crypto_register_algs() succeeds if and only if it
-       successfully registers all the given transformations. If an
-       error occurs partway through, then it rolls back successful
-       registrations before returning the error code. Note that if
-       a driver needs to handle registration errors for individual
-       transformations, then it will need to use the non-bulk
-       function crypto_register_alg() instead.
-      </para>
-     </listitem>
-     <listitem>
-      <para>
-       crypto_unregister_algs() tries to unregister all the given
-       transformations, continuing on error. It logs errors and
-       always returns zero.
-      </para>
-     </listitem>
-    </itemizedlist>
-
-   </sect1>
-
-   <sect1><title>Single-Block Symmetric Ciphers [CIPHER]</title>
-    <para>
-     Example of transformations: aes, arc4, ...
-    </para>
-
-    <para>
-     This section describes the simplest of all transformation
-     implementations, that being the CIPHER type used for symmetric
-     ciphers. The CIPHER type is used for transformations which
-     operate on exactly one block at a time and there are no
-     dependencies between blocks at all.
-    </para>
-
-    <sect2><title>Registration specifics</title>
-     <para>
-      The registration of [CIPHER] algorithm is specific in that
-      struct crypto_alg field .cra_type is empty. The .cra_u.cipher
-      has to be filled in with proper callbacks to implement this
-      transformation.
-     </para>
-
-     <para>
-      See struct cipher_alg below.
-     </para>
-    </sect2>
-
-    <sect2><title>Cipher Definition With struct cipher_alg</title>
-     <para>
-      Struct cipher_alg defines a single block cipher.
-     </para>
-
-     <para>
-      Here are schematics of how these functions are called when
-      operated from other part of the kernel. Note that the
-      .cia_setkey() call might happen before or after any of these
-      schematics happen, but must not happen during any of these
-      are in-flight.
-     </para>
-
-     <para>
-      <programlisting>
-         KEY ---.    PLAINTEXT ---.
-                v                 v
-          .cia_setkey() -&gt; .cia_encrypt()
-                                  |
-                                  '-----&gt; CIPHERTEXT
-      </programlisting>
-     </para>
-
-     <para>
-      Please note that a pattern where .cia_setkey() is called
-      multiple times is also valid:
-     </para>
-
-     <para>
-      <programlisting>
-
-  KEY1 --.    PLAINTEXT1 --.         KEY2 --.    PLAINTEXT2 --.
-         v                 v                v                 v
-   .cia_setkey() -&gt; .cia_encrypt() -&gt; .cia_setkey() -&gt; .cia_encrypt()
-                           |                                  |
-                           '---&gt; CIPHERTEXT1                  '---&gt; CIPHERTEXT2
-      </programlisting>
-     </para>
-
-    </sect2>
-   </sect1>
-
-   <sect1><title>Multi-Block Ciphers</title>
-    <para>
-     Example of transformations: cbc(aes), ecb(arc4), ...
-    </para>
-
-    <para>
-     This section describes the multi-block cipher transformation
-     implementations. The multi-block ciphers are
-     used for transformations which operate on scatterlists of
-     data supplied to the transformation functions. They output
-     the result into a scatterlist of data as well.
-    </para>
-
-    <sect2><title>Registration Specifics</title>
-
-     <para>
-      The registration of multi-block cipher algorithms
-      is one of the most standard procedures throughout the crypto API.
-     </para>
-
-     <para>
-      Note, if a cipher implementation requires a proper alignment
-      of data, the caller should use the functions of
-      crypto_skcipher_alignmask() to identify a memory alignment mask.
-      The kernel crypto API is able to process requests that are unaligned.
-      This implies, however, additional overhead as the kernel
-      crypto API needs to perform the realignment of the data which
-      may imply moving of data.
-     </para>
-    </sect2>
-
-    <sect2><title>Cipher Definition With struct blkcipher_alg and ablkcipher_alg</title>
-     <para>
-      Struct blkcipher_alg defines a synchronous block cipher whereas
-      struct ablkcipher_alg defines an asynchronous block cipher.
-     </para>
-
-     <para>
-      Please refer to the single block cipher description for schematics
-      of the block cipher usage.
-     </para>
-    </sect2>
-
-    <sect2><title>Specifics Of Asynchronous Multi-Block Cipher</title>
-     <para>
-      There are a couple of specifics to the asynchronous interface.
-     </para>
-
-     <para>
-      First of all, some of the drivers will want to use the
-      Generic ScatterWalk in case the hardware needs to be fed
-      separate chunks of the scatterlist which contains the
-      plaintext and will contain the ciphertext. Please refer
-      to the ScatterWalk interface offered by the Linux kernel
-      scatter / gather list implementation.
-     </para>
-    </sect2>
-   </sect1>
-
-   <sect1><title>Hashing [HASH]</title>
-
-    <para>
-     Example of transformations: crc32, md5, sha1, sha256,...
-    </para>
-
-    <sect2><title>Registering And Unregistering The Transformation</title>
-
-     <para>
-      There are multiple ways to register a HASH transformation,
-      depending on whether the transformation is synchronous [SHASH]
-      or asynchronous [AHASH] and the amount of HASH transformations
-      we are registering. You can find the prototypes defined in
-      include/crypto/internal/hash.h:
-     </para>
-
-     <programlisting>
-   int crypto_register_ahash(struct ahash_alg *alg);
-
-   int crypto_register_shash(struct shash_alg *alg);
-   int crypto_register_shashes(struct shash_alg *algs, int count);
-     </programlisting>
-
-     <para>
-      The respective counterparts for unregistering the HASH
-      transformation are as follows:
-     </para>
-
-     <programlisting>
-   int crypto_unregister_ahash(struct ahash_alg *alg);
-
-   int crypto_unregister_shash(struct shash_alg *alg);
-   int crypto_unregister_shashes(struct shash_alg *algs, int count);
-     </programlisting>
-    </sect2>
-
-    <sect2><title>Cipher Definition With struct shash_alg and ahash_alg</title>
-     <para>
-      Here are schematics of how these functions are called when
-      operated from other part of the kernel. Note that the .setkey()
-      call might happen before or after any of these schematics happen,
-      but must not happen during any of these are in-flight. Please note
-      that calling .init() followed immediately by .finish() is also a
-      perfectly valid transformation.
-     </para>
-
-     <programlisting>
-   I)   DATA -----------.
-                        v
-         .init() -&gt; .update() -&gt; .final()      ! .update() might not be called
-                     ^    |         |            at all in this scenario.
-                     '----'         '---&gt; HASH
-
-   II)  DATA -----------.-----------.
-                        v           v
-         .init() -&gt; .update() -&gt; .finup()      ! .update() may not be called
-                     ^    |         |            at all in this scenario.
-                     '----'         '---&gt; HASH
-
-   III) DATA -----------.
-                        v
-                    .digest()                  ! The entire process is handled
-                        |                        by the .digest() call.
-                        '---------------&gt; HASH
-     </programlisting>
-
-     <para>
-      Here is a schematic of how the .export()/.import() functions are
-      called when used from another part of the kernel.
-     </para>
-
-     <programlisting>
-   KEY--.                 DATA--.
-        v                       v                  ! .update() may not be called
-    .setkey() -&gt; .init() -&gt; .update() -&gt; .export()   at all in this scenario.
-                             ^     |         |
-                             '-----'         '--&gt; PARTIAL_HASH
-
-   ----------- other transformations happen here -----------
-
-   PARTIAL_HASH--.   DATA1--.
-                 v          v
-             .import -&gt; .update() -&gt; .final()     ! .update() may not be called
-                         ^    |         |           at all in this scenario.
-                         '----'         '--&gt; HASH1
-
-   PARTIAL_HASH--.   DATA2-.
-                 v         v
-             .import -&gt; .finup()
-                           |
-                           '---------------&gt; HASH2
-     </programlisting>
-    </sect2>
-
-    <sect2><title>Specifics Of Asynchronous HASH Transformation</title>
-     <para>
-      Some of the drivers will want to use the Generic ScatterWalk
-      in case the implementation needs to be fed separate chunks of the
-      scatterlist which contains the input data. The buffer containing
-      the resulting hash will always be properly aligned to
-      .cra_alignmask so there is no need to worry about this.
-     </para>
-    </sect2>
-   </sect1>
-  </chapter>
-
-  <chapter id="User"><title>User Space Interface</title>
-   <sect1><title>Introduction</title>
-    <para>
-     The concepts of the kernel crypto API visible to kernel space is fully
-     applicable to the user space interface as well. Therefore, the kernel
-     crypto API high level discussion for the in-kernel use cases applies
-     here as well.
-    </para>
-
-    <para>
-     The major difference, however, is that user space can only act as a
-     consumer and never as a provider of a transformation or cipher algorithm.
-    </para>
-
-    <para>
-     The following covers the user space interface exported by the kernel
-     crypto API. A working example of this description is libkcapi that
-     can be obtained from [1]. That library can be used by user space
-     applications that require cryptographic services from the kernel.
-    </para>
-
-    <para>
-     Some details of the in-kernel kernel crypto API aspects do not
-     apply to user space, however. This includes the difference between
-     synchronous and asynchronous invocations. The user space API call
-     is fully synchronous.
-    </para>
-
-    <para>
-     [1] <ulink url="http://www.chronox.de/libkcapi.html">http://www.chronox.de/libkcapi.html</ulink>
-    </para>
-
-   </sect1>
-
-   <sect1><title>User Space API General Remarks</title>
-    <para>
-     The kernel crypto API is accessible from user space. Currently,
-     the following ciphers are accessible:
-    </para>
-
-    <itemizedlist>
-     <listitem>
-      <para>Message digest including keyed message digest (HMAC, CMAC)</para>
-     </listitem>
-
-     <listitem>
-      <para>Symmetric ciphers</para>
-     </listitem>
-
-     <listitem>
-      <para>AEAD ciphers</para>
-     </listitem>
-
-     <listitem>
-      <para>Random Number Generators</para>
-     </listitem>
-    </itemizedlist>
-
-    <para>
-     The interface is provided via socket type using the type AF_ALG.
-     In addition, the setsockopt option type is SOL_ALG. In case the
-     user space header files do not export these flags yet, use the
-     following macros:
-    </para>
-
-    <programlisting>
-#ifndef AF_ALG
-#define AF_ALG 38
-#endif
-#ifndef SOL_ALG
-#define SOL_ALG 279
-#endif
-    </programlisting>
-
-    <para>
-     A cipher is accessed with the same name as done for the in-kernel
-     API calls. This includes the generic vs. unique naming schema for
-     ciphers as well as the enforcement of priorities for generic names.
-    </para>
-
-    <para>
-     To interact with the kernel crypto API, a socket must be
-     created by the user space application. User space invokes the cipher
-     operation with the send()/write() system call family. The result of the
-     cipher operation is obtained with the read()/recv() system call family.
-    </para>
-
-    <para>
-     The following API calls assume that the socket descriptor
-     is already opened by the user space application and discusses only
-     the kernel crypto API specific invocations.
-    </para>
-
-    <para>
-     To initialize the socket interface, the following sequence has to
-     be performed by the consumer:
-    </para>
-
-    <orderedlist>
-     <listitem>
-      <para>
-       Create a socket of type AF_ALG with the struct sockaddr_alg
-       parameter specified below for the different cipher types.
-      </para>
-     </listitem>
-
-     <listitem>
-      <para>
-       Invoke bind with the socket descriptor
-      </para>
-     </listitem>
-
-     <listitem>
-      <para>
-       Invoke accept with the socket descriptor. The accept system call
-       returns a new file descriptor that is to be used to interact with
-       the particular cipher instance. When invoking send/write or recv/read
-       system calls to send data to the kernel or obtain data from the
-       kernel, the file descriptor returned by accept must be used.
-      </para>
-     </listitem>
-    </orderedlist>
-   </sect1>
-
-   <sect1><title>In-place Cipher operation</title>
-    <para>
-     Just like the in-kernel operation of the kernel crypto API, the user
-     space interface allows the cipher operation in-place. That means that
-     the input buffer used for the send/write system call and the output
-     buffer used by the read/recv system call may be one and the same.
-     This is of particular interest for symmetric cipher operations where a
-     copying of the output data to its final destination can be avoided.
-    </para>
-
-    <para>
-     If a consumer on the other hand wants to maintain the plaintext and
-     the ciphertext in different memory locations, all a consumer needs
-     to do is to provide different memory pointers for the encryption and
-     decryption operation.
-    </para>
-   </sect1>
-
-   <sect1><title>Message Digest API</title>
-    <para>
-     The message digest type to be used for the cipher operation is
-     selected when invoking the bind syscall. bind requires the caller
-     to provide a filled struct sockaddr data structure. This data
-     structure must be filled as follows:
-    </para>
-
-    <programlisting>
-struct sockaddr_alg sa = {
-	.salg_family = AF_ALG,
-	.salg_type = "hash", /* this selects the hash logic in the kernel */
-	.salg_name = "sha1" /* this is the cipher name */
-};
-    </programlisting>
-
-    <para>
-     The salg_type value "hash" applies to message digests and keyed
-     message digests. Though, a keyed message digest is referenced by
-     the appropriate salg_name. Please see below for the setsockopt
-     interface that explains how the key can be set for a keyed message
-     digest.
-    </para>
-
-    <para>
-     Using the send() system call, the application provides the data that
-     should be processed with the message digest. The send system call
-     allows the following flags to be specified:
-    </para>
-
-    <itemizedlist>
-     <listitem>
-      <para>
-       MSG_MORE: If this flag is set, the send system call acts like a
-       message digest update function where the final hash is not
-       yet calculated. If the flag is not set, the send system call
-       calculates the final message digest immediately.
-      </para>
-     </listitem>
-    </itemizedlist>
-
-    <para>
-     With the recv() system call, the application can read the message
-     digest from the kernel crypto API. If the buffer is too small for the
-     message digest, the flag MSG_TRUNC is set by the kernel.
-    </para>
-
-    <para>
-     In order to set a message digest key, the calling application must use
-     the setsockopt() option of ALG_SET_KEY. If the key is not set the HMAC
-     operation is performed without the initial HMAC state change caused by
-     the key.
-    </para>
-   </sect1>
-
-   <sect1><title>Symmetric Cipher API</title>
-    <para>
-     The operation is very similar to the message digest discussion.
-     During initialization, the struct sockaddr data structure must be
-     filled as follows:
-    </para>
-
-    <programlisting>
-struct sockaddr_alg sa = {
-	.salg_family = AF_ALG,
-	.salg_type = "skcipher", /* this selects the symmetric cipher */
-	.salg_name = "cbc(aes)" /* this is the cipher name */
-};
-    </programlisting>
-
-    <para>
-     Before data can be sent to the kernel using the write/send system
-     call family, the consumer must set the key. The key setting is
-     described with the setsockopt invocation below.
-    </para>
-
-    <para>
-     Using the sendmsg() system call, the application provides the data that should be processed for encryption or decryption. In addition, the IV is
-     specified with the data structure provided by the sendmsg() system call.
-    </para>
-
-    <para>
-     The sendmsg system call parameter of struct msghdr is embedded into the
-     struct cmsghdr data structure. See recv(2) and cmsg(3) for more
-     information on how the cmsghdr data structure is used together with the
-     send/recv system call family. That cmsghdr data structure holds the
-     following information specified with a separate header instances:
-    </para>
-
-    <itemizedlist>
-     <listitem>
-      <para>
-       specification of the cipher operation type with one of these flags:
-      </para>
-      <itemizedlist>
-       <listitem>
-        <para>ALG_OP_ENCRYPT - encryption of data</para>
-       </listitem>
-       <listitem>
-        <para>ALG_OP_DECRYPT - decryption of data</para>
-       </listitem>
-      </itemizedlist>
-     </listitem>
-
-     <listitem>
-      <para>
-       specification of the IV information marked with the flag ALG_SET_IV
-      </para>
-     </listitem>
-    </itemizedlist>
-
-    <para>
-     The send system call family allows the following flag to be specified:
-    </para>
-
-    <itemizedlist>
-     <listitem>
-      <para>
-       MSG_MORE: If this flag is set, the send system call acts like a
-       cipher update function where more input data is expected
-       with a subsequent invocation of the send system call.
-      </para>
-     </listitem>
-    </itemizedlist>
-
-    <para>
-     Note: The kernel reports -EINVAL for any unexpected data. The caller
-     must make sure that all data matches the constraints given in
-     /proc/crypto for the selected cipher.
-    </para>
-
-    <para>
-     With the recv() system call, the application can read the result of
-     the cipher operation from the kernel crypto API. The output buffer
-     must be at least as large as to hold all blocks of the encrypted or
-     decrypted data. If the output data size is smaller, only as many
-     blocks are returned that fit into that output buffer size.
-    </para>
-   </sect1>
-
-   <sect1><title>AEAD Cipher API</title>
-    <para>
-     The operation is very similar to the symmetric cipher discussion.
-     During initialization, the struct sockaddr data structure must be
-     filled as follows:
-    </para>
-
-    <programlisting>
-struct sockaddr_alg sa = {
-	.salg_family = AF_ALG,
-	.salg_type = "aead", /* this selects the symmetric cipher */
-	.salg_name = "gcm(aes)" /* this is the cipher name */
-};
-    </programlisting>
-
-    <para>
-     Before data can be sent to the kernel using the write/send system
-     call family, the consumer must set the key. The key setting is
-     described with the setsockopt invocation below.
-    </para>
-
-    <para>
-     In addition, before data can be sent to the kernel using the
-     write/send system call family, the consumer must set the authentication
-     tag size. To set the authentication tag size, the caller must use the
-     setsockopt invocation described below.
-    </para>
-
-    <para>
-     Using the sendmsg() system call, the application provides the data that should be processed for encryption or decryption. In addition, the IV is
-     specified with the data structure provided by the sendmsg() system call.
-    </para>
-
-    <para>
-     The sendmsg system call parameter of struct msghdr is embedded into the
-     struct cmsghdr data structure. See recv(2) and cmsg(3) for more
-     information on how the cmsghdr data structure is used together with the
-     send/recv system call family. That cmsghdr data structure holds the
-     following information specified with a separate header instances:
-    </para>
-
-    <itemizedlist>
-     <listitem>
-      <para>
-       specification of the cipher operation type with one of these flags:
-      </para>
-      <itemizedlist>
-       <listitem>
-        <para>ALG_OP_ENCRYPT - encryption of data</para>
-       </listitem>
-       <listitem>
-        <para>ALG_OP_DECRYPT - decryption of data</para>
-       </listitem>
-      </itemizedlist>
-     </listitem>
-
-     <listitem>
-      <para>
-       specification of the IV information marked with the flag ALG_SET_IV
-      </para>
-     </listitem>
-
-     <listitem>
-      <para>
-       specification of the associated authentication data (AAD) with the
-       flag ALG_SET_AEAD_ASSOCLEN. The AAD is sent to the kernel together
-       with the plaintext / ciphertext. See below for the memory structure.
-      </para>
-     </listitem>
-    </itemizedlist>
-
-    <para>
-     The send system call family allows the following flag to be specified:
-    </para>
-
-    <itemizedlist>
-     <listitem>
-      <para>
-       MSG_MORE: If this flag is set, the send system call acts like a
-       cipher update function where more input data is expected
-       with a subsequent invocation of the send system call.
-      </para>
-     </listitem>
-    </itemizedlist>
-
-    <para>
-     Note: The kernel reports -EINVAL for any unexpected data. The caller
-     must make sure that all data matches the constraints given in
-     /proc/crypto for the selected cipher.
-    </para>
-
-    <para>
-     With the recv() system call, the application can read the result of
-     the cipher operation from the kernel crypto API. The output buffer
-     must be at least as large as defined with the memory structure below.
-     If the output data size is smaller, the cipher operation is not performed.
-    </para>
-
-    <para>
-     The authenticated decryption operation may indicate an integrity error.
-     Such breach in integrity is marked with the -EBADMSG error code.
-    </para>
-
-    <sect2><title>AEAD Memory Structure</title>
-     <para>
-      The AEAD cipher operates with the following information that
-      is communicated between user and kernel space as one data stream:
-     </para>
-
-     <itemizedlist>
-      <listitem>
-       <para>plaintext or ciphertext</para>
-      </listitem>
-
-      <listitem>
-       <para>associated authentication data (AAD)</para>
-      </listitem>
-
-      <listitem>
-       <para>authentication tag</para>
-      </listitem>
-     </itemizedlist>
-
-     <para>
-      The sizes of the AAD and the authentication tag are provided with
-      the sendmsg and setsockopt calls (see there). As the kernel knows
-      the size of the entire data stream, the kernel is now able to
-      calculate the right offsets of the data components in the data
-      stream.
-     </para>
-
-     <para>
-      The user space caller must arrange the aforementioned information
-      in the following order:
-     </para>
-
-     <itemizedlist>
-      <listitem>
-       <para>
-        AEAD encryption input: AAD || plaintext
-       </para>
-      </listitem>
-
-      <listitem>
-       <para>
-        AEAD decryption input: AAD || ciphertext || authentication tag
-       </para>
-      </listitem>
-     </itemizedlist>
-
-     <para>
-      The output buffer the user space caller provides must be at least as
-      large to hold the following data:
-     </para>
-
-     <itemizedlist>
-      <listitem>
-       <para>
-        AEAD encryption output: ciphertext || authentication tag
-       </para>
-      </listitem>
-
-      <listitem>
-       <para>
-        AEAD decryption output: plaintext
-       </para>
-      </listitem>
-     </itemizedlist>
-    </sect2>
-   </sect1>
-
-   <sect1><title>Random Number Generator API</title>
-    <para>
-     Again, the operation is very similar to the other APIs.
-     During initialization, the struct sockaddr data structure must be
-     filled as follows:
-    </para>
-
-    <programlisting>
-struct sockaddr_alg sa = {
-	.salg_family = AF_ALG,
-	.salg_type = "rng", /* this selects the symmetric cipher */
-	.salg_name = "drbg_nopr_sha256" /* this is the cipher name */
-};
-    </programlisting>
-
-    <para>
-     Depending on the RNG type, the RNG must be seeded. The seed is provided
-     using the setsockopt interface to set the key. For example, the
-     ansi_cprng requires a seed. The DRBGs do not require a seed, but
-     may be seeded.
-    </para>
-
-    <para>
-     Using the read()/recvmsg() system calls, random numbers can be obtained.
-     The kernel generates at most 128 bytes in one call. If user space
-     requires more data, multiple calls to read()/recvmsg() must be made.
-    </para>
-
-    <para>
-     WARNING: The user space caller may invoke the initially mentioned
-     accept system call multiple times. In this case, the returned file
-     descriptors have the same state.
-    </para>
-
-   </sect1>
-
-   <sect1><title>Zero-Copy Interface</title>
-    <para>
-     In addition to the send/write/read/recv system call family, the AF_ALG
-     interface can be accessed with the zero-copy interface of splice/vmsplice.
-     As the name indicates, the kernel tries to avoid a copy operation into
-     kernel space.
-    </para>
-
-    <para>
-     The zero-copy operation requires data to be aligned at the page boundary.
-     Non-aligned data can be used as well, but may require more operations of
-     the kernel which would defeat the speed gains obtained from the zero-copy
-     interface.
-    </para>
-
-    <para>
-     The system-interent limit for the size of one zero-copy operation is
-     16 pages. If more data is to be sent to AF_ALG, user space must slice
-     the input into segments with a maximum size of 16 pages.
-    </para>
-
-    <para>
-     Zero-copy can be used with the following code example (a complete working
-     example is provided with libkcapi):
-    </para>
-
-    <programlisting>
-int pipes[2];
-
-pipe(pipes);
-/* input data in iov */
-vmsplice(pipes[1], iov, iovlen, SPLICE_F_GIFT);
-/* opfd is the file descriptor returned from accept() system call */
-splice(pipes[0], NULL, opfd, NULL, ret, 0);
-read(opfd, out, outlen);
-    </programlisting>
-
-   </sect1>
-
-   <sect1><title>Setsockopt Interface</title>
-    <para>
-     In addition to the read/recv and send/write system call handling
-     to send and retrieve data subject to the cipher operation, a consumer
-     also needs to set the additional information for the cipher operation.
-     This additional information is set using the setsockopt system call
-     that must be invoked with the file descriptor of the open cipher
-     (i.e. the file descriptor returned by the accept system call).
-    </para>
-
-    <para>
-     Each setsockopt invocation must use the level SOL_ALG.
-    </para>
-
-    <para>
-     The setsockopt interface allows setting the following data using
-     the mentioned optname:
-    </para>
-
-    <itemizedlist>
-     <listitem>
-      <para>
-       ALG_SET_KEY -- Setting the key. Key setting is applicable to:
-      </para>
-      <itemizedlist>
-       <listitem>
-        <para>the skcipher cipher type (symmetric ciphers)</para>
-       </listitem>
-       <listitem>
-        <para>the hash cipher type (keyed message digests)</para>
-       </listitem>
-       <listitem>
-        <para>the AEAD cipher type</para>
-       </listitem>
-       <listitem>
-        <para>the RNG cipher type to provide the seed</para>
-       </listitem>
-      </itemizedlist>
-     </listitem>
-
-     <listitem>
-      <para>
-       ALG_SET_AEAD_AUTHSIZE -- Setting the authentication tag size
-       for AEAD ciphers. For a encryption operation, the authentication
-       tag of the given size will be generated. For a decryption operation,
-       the provided ciphertext is assumed to contain an authentication tag
-       of the given size (see section about AEAD memory layout below).
-      </para>
-     </listitem>
-    </itemizedlist>
-
-   </sect1>
-
-   <sect1><title>User space API example</title>
-    <para>
-     Please see [1] for libkcapi which provides an easy-to-use wrapper
-     around the aforementioned Netlink kernel interface. [1] also contains
-     a test application that invokes all libkcapi API calls.
-    </para>
-
-    <para>
-     [1] <ulink url="http://www.chronox.de/libkcapi.html">http://www.chronox.de/libkcapi.html</ulink>
-    </para>
-
-   </sect1>
-
-  </chapter>
-
-  <chapter id="API"><title>Programming Interface</title>
-   <para>
-    Please note that the kernel crypto API contains the AEAD givcrypt
-    API (crypto_aead_giv* and aead_givcrypt_* function calls in
-    include/crypto/aead.h). This API is obsolete and will be removed
-    in the future. To obtain the functionality of an AEAD cipher with
-    internal IV generation, use the IV generator as a regular cipher.
-    For example, rfc4106(gcm(aes)) is the AEAD cipher with external
-    IV generation and seqniv(rfc4106(gcm(aes))) implies that the kernel
-    crypto API generates the IV. Different IV generators are available.
-   </para>
-   <sect1><title>Block Cipher Context Data Structures</title>
-!Pinclude/linux/crypto.h Block Cipher Context Data Structures
-!Finclude/crypto/aead.h aead_request
-   </sect1>
-   <sect1><title>Block Cipher Algorithm Definitions</title>
-!Pinclude/linux/crypto.h Block Cipher Algorithm Definitions
-!Finclude/linux/crypto.h crypto_alg
-!Finclude/linux/crypto.h ablkcipher_alg
-!Finclude/crypto/aead.h aead_alg
-!Finclude/linux/crypto.h blkcipher_alg
-!Finclude/linux/crypto.h cipher_alg
-!Finclude/crypto/rng.h rng_alg
-   </sect1>
-   <sect1><title>Symmetric Key Cipher API</title>
-!Pinclude/crypto/skcipher.h Symmetric Key Cipher API
-!Finclude/crypto/skcipher.h crypto_alloc_skcipher
-!Finclude/crypto/skcipher.h crypto_free_skcipher
-!Finclude/crypto/skcipher.h crypto_has_skcipher
-!Finclude/crypto/skcipher.h crypto_skcipher_ivsize
-!Finclude/crypto/skcipher.h crypto_skcipher_blocksize
-!Finclude/crypto/skcipher.h crypto_skcipher_setkey
-!Finclude/crypto/skcipher.h crypto_skcipher_reqtfm
-!Finclude/crypto/skcipher.h crypto_skcipher_encrypt
-!Finclude/crypto/skcipher.h crypto_skcipher_decrypt
-   </sect1>
-   <sect1><title>Symmetric Key Cipher Request Handle</title>
-!Pinclude/crypto/skcipher.h Symmetric Key Cipher Request Handle
-!Finclude/crypto/skcipher.h crypto_skcipher_reqsize
-!Finclude/crypto/skcipher.h skcipher_request_set_tfm
-!Finclude/crypto/skcipher.h skcipher_request_alloc
-!Finclude/crypto/skcipher.h skcipher_request_free
-!Finclude/crypto/skcipher.h skcipher_request_set_callback
-!Finclude/crypto/skcipher.h skcipher_request_set_crypt
-   </sect1>
-   <sect1><title>Asynchronous Block Cipher API - Deprecated</title>
-!Pinclude/linux/crypto.h Asynchronous Block Cipher API
-!Finclude/linux/crypto.h crypto_alloc_ablkcipher
-!Finclude/linux/crypto.h crypto_free_ablkcipher
-!Finclude/linux/crypto.h crypto_has_ablkcipher
-!Finclude/linux/crypto.h crypto_ablkcipher_ivsize
-!Finclude/linux/crypto.h crypto_ablkcipher_blocksize
-!Finclude/linux/crypto.h crypto_ablkcipher_setkey
-!Finclude/linux/crypto.h crypto_ablkcipher_reqtfm
-!Finclude/linux/crypto.h crypto_ablkcipher_encrypt
-!Finclude/linux/crypto.h crypto_ablkcipher_decrypt
-   </sect1>
-   <sect1><title>Asynchronous Cipher Request Handle - Deprecated</title>
-!Pinclude/linux/crypto.h Asynchronous Cipher Request Handle
-!Finclude/linux/crypto.h crypto_ablkcipher_reqsize
-!Finclude/linux/crypto.h ablkcipher_request_set_tfm
-!Finclude/linux/crypto.h ablkcipher_request_alloc
-!Finclude/linux/crypto.h ablkcipher_request_free
-!Finclude/linux/crypto.h ablkcipher_request_set_callback
-!Finclude/linux/crypto.h ablkcipher_request_set_crypt
-   </sect1>
-   <sect1><title>Authenticated Encryption With Associated Data (AEAD) Cipher API</title>
-!Pinclude/crypto/aead.h Authenticated Encryption With Associated Data (AEAD) Cipher API
-!Finclude/crypto/aead.h crypto_alloc_aead
-!Finclude/crypto/aead.h crypto_free_aead
-!Finclude/crypto/aead.h crypto_aead_ivsize
-!Finclude/crypto/aead.h crypto_aead_authsize
-!Finclude/crypto/aead.h crypto_aead_blocksize
-!Finclude/crypto/aead.h crypto_aead_setkey
-!Finclude/crypto/aead.h crypto_aead_setauthsize
-!Finclude/crypto/aead.h crypto_aead_encrypt
-!Finclude/crypto/aead.h crypto_aead_decrypt
-   </sect1>
-   <sect1><title>Asynchronous AEAD Request Handle</title>
-!Pinclude/crypto/aead.h Asynchronous AEAD Request Handle
-!Finclude/crypto/aead.h crypto_aead_reqsize
-!Finclude/crypto/aead.h aead_request_set_tfm
-!Finclude/crypto/aead.h aead_request_alloc
-!Finclude/crypto/aead.h aead_request_free
-!Finclude/crypto/aead.h aead_request_set_callback
-!Finclude/crypto/aead.h aead_request_set_crypt
-!Finclude/crypto/aead.h aead_request_set_ad
-   </sect1>
-   <sect1><title>Synchronous Block Cipher API - Deprecated</title>
-!Pinclude/linux/crypto.h Synchronous Block Cipher API
-!Finclude/linux/crypto.h crypto_alloc_blkcipher
-!Finclude/linux/crypto.h crypto_free_blkcipher
-!Finclude/linux/crypto.h crypto_has_blkcipher
-!Finclude/linux/crypto.h crypto_blkcipher_name
-!Finclude/linux/crypto.h crypto_blkcipher_ivsize
-!Finclude/linux/crypto.h crypto_blkcipher_blocksize
-!Finclude/linux/crypto.h crypto_blkcipher_setkey
-!Finclude/linux/crypto.h crypto_blkcipher_encrypt
-!Finclude/linux/crypto.h crypto_blkcipher_encrypt_iv
-!Finclude/linux/crypto.h crypto_blkcipher_decrypt
-!Finclude/linux/crypto.h crypto_blkcipher_decrypt_iv
-!Finclude/linux/crypto.h crypto_blkcipher_set_iv
-!Finclude/linux/crypto.h crypto_blkcipher_get_iv
-   </sect1>
-   <sect1><title>Single Block Cipher API</title>
-!Pinclude/linux/crypto.h Single Block Cipher API
-!Finclude/linux/crypto.h crypto_alloc_cipher
-!Finclude/linux/crypto.h crypto_free_cipher
-!Finclude/linux/crypto.h crypto_has_cipher
-!Finclude/linux/crypto.h crypto_cipher_blocksize
-!Finclude/linux/crypto.h crypto_cipher_setkey
-!Finclude/linux/crypto.h crypto_cipher_encrypt_one
-!Finclude/linux/crypto.h crypto_cipher_decrypt_one
-   </sect1>
-   <sect1><title>Message Digest Algorithm Definitions</title>
-!Pinclude/crypto/hash.h Message Digest Algorithm Definitions
-!Finclude/crypto/hash.h hash_alg_common
-!Finclude/crypto/hash.h ahash_alg
-!Finclude/crypto/hash.h shash_alg
-   </sect1>
-   <sect1><title>Asynchronous Message Digest API</title>
-!Pinclude/crypto/hash.h Asynchronous Message Digest API
-!Finclude/crypto/hash.h crypto_alloc_ahash
-!Finclude/crypto/hash.h crypto_free_ahash
-!Finclude/crypto/hash.h crypto_ahash_init
-!Finclude/crypto/hash.h crypto_ahash_digestsize
-!Finclude/crypto/hash.h crypto_ahash_reqtfm
-!Finclude/crypto/hash.h crypto_ahash_reqsize
-!Finclude/crypto/hash.h crypto_ahash_setkey
-!Finclude/crypto/hash.h crypto_ahash_finup
-!Finclude/crypto/hash.h crypto_ahash_final
-!Finclude/crypto/hash.h crypto_ahash_digest
-!Finclude/crypto/hash.h crypto_ahash_export
-!Finclude/crypto/hash.h crypto_ahash_import
-   </sect1>
-   <sect1><title>Asynchronous Hash Request Handle</title>
-!Pinclude/crypto/hash.h Asynchronous Hash Request Handle
-!Finclude/crypto/hash.h ahash_request_set_tfm
-!Finclude/crypto/hash.h ahash_request_alloc
-!Finclude/crypto/hash.h ahash_request_free
-!Finclude/crypto/hash.h ahash_request_set_callback
-!Finclude/crypto/hash.h ahash_request_set_crypt
-   </sect1>
-   <sect1><title>Synchronous Message Digest API</title>
-!Pinclude/crypto/hash.h Synchronous Message Digest API
-!Finclude/crypto/hash.h crypto_alloc_shash
-!Finclude/crypto/hash.h crypto_free_shash
-!Finclude/crypto/hash.h crypto_shash_blocksize
-!Finclude/crypto/hash.h crypto_shash_digestsize
-!Finclude/crypto/hash.h crypto_shash_descsize
-!Finclude/crypto/hash.h crypto_shash_setkey
-!Finclude/crypto/hash.h crypto_shash_digest
-!Finclude/crypto/hash.h crypto_shash_export
-!Finclude/crypto/hash.h crypto_shash_import
-!Finclude/crypto/hash.h crypto_shash_init
-!Finclude/crypto/hash.h crypto_shash_update
-!Finclude/crypto/hash.h crypto_shash_final
-!Finclude/crypto/hash.h crypto_shash_finup
-   </sect1>
-   <sect1><title>Crypto API Random Number API</title>
-!Pinclude/crypto/rng.h Random number generator API
-!Finclude/crypto/rng.h crypto_alloc_rng
-!Finclude/crypto/rng.h crypto_rng_alg
-!Finclude/crypto/rng.h crypto_free_rng
-!Finclude/crypto/rng.h crypto_rng_generate
-!Finclude/crypto/rng.h crypto_rng_get_bytes
-!Finclude/crypto/rng.h crypto_rng_reset
-!Finclude/crypto/rng.h crypto_rng_seedsize
-!Cinclude/crypto/rng.h
-   </sect1>
-   <sect1><title>Asymmetric Cipher API</title>
-!Pinclude/crypto/akcipher.h Generic Public Key API
-!Finclude/crypto/akcipher.h akcipher_alg
-!Finclude/crypto/akcipher.h akcipher_request
-!Finclude/crypto/akcipher.h crypto_alloc_akcipher
-!Finclude/crypto/akcipher.h crypto_free_akcipher
-!Finclude/crypto/akcipher.h crypto_akcipher_set_pub_key
-!Finclude/crypto/akcipher.h crypto_akcipher_set_priv_key
-   </sect1>
-   <sect1><title>Asymmetric Cipher Request Handle</title>
-!Finclude/crypto/akcipher.h akcipher_request_alloc
-!Finclude/crypto/akcipher.h akcipher_request_free
-!Finclude/crypto/akcipher.h akcipher_request_set_callback
-!Finclude/crypto/akcipher.h akcipher_request_set_crypt
-!Finclude/crypto/akcipher.h crypto_akcipher_maxsize
-!Finclude/crypto/akcipher.h crypto_akcipher_encrypt
-!Finclude/crypto/akcipher.h crypto_akcipher_decrypt
-!Finclude/crypto/akcipher.h crypto_akcipher_sign
-!Finclude/crypto/akcipher.h crypto_akcipher_verify
-   </sect1>
-  </chapter>
-
-  <chapter id="Code"><title>Code Examples</title>
-   <sect1><title>Code Example For Symmetric Key Cipher Operation</title>
-    <programlisting>
-
-struct tcrypt_result {
-	struct completion completion;
-	int err;
-};
-
-/* tie all data structures together */
-struct skcipher_def {
-	struct scatterlist sg;
-	struct crypto_skcipher *tfm;
-	struct skcipher_request *req;
-	struct tcrypt_result result;
-};
-
-/* Callback function */
-static void test_skcipher_cb(struct crypto_async_request *req, int error)
-{
-	struct tcrypt_result *result = req-&gt;data;
-
-	if (error == -EINPROGRESS)
-		return;
-	result-&gt;err = error;
-	complete(&amp;result-&gt;completion);
-	pr_info("Encryption finished successfully\n");
-}
-
-/* Perform cipher operation */
-static unsigned int test_skcipher_encdec(struct skcipher_def *sk,
-					 int enc)
-{
-	int rc = 0;
-
-	if (enc)
-		rc = crypto_skcipher_encrypt(sk-&gt;req);
-	else
-		rc = crypto_skcipher_decrypt(sk-&gt;req);
-
-	switch (rc) {
-	case 0:
-		break;
-	case -EINPROGRESS:
-	case -EBUSY:
-		rc = wait_for_completion_interruptible(
-			&amp;sk-&gt;result.completion);
-		if (!rc &amp;&amp; !sk-&gt;result.err) {
-			reinit_completion(&amp;sk-&gt;result.completion);
-			break;
-		}
-	default:
-		pr_info("skcipher encrypt returned with %d result %d\n",
-			rc, sk-&gt;result.err);
-		break;
-	}
-	init_completion(&amp;sk-&gt;result.completion);
-
-	return rc;
-}
-
-/* Initialize and trigger cipher operation */
-static int test_skcipher(void)
-{
-	struct skcipher_def sk;
-	struct crypto_skcipher *skcipher = NULL;
-	struct skcipher_request *req = NULL;
-	char *scratchpad = NULL;
-	char *ivdata = NULL;
-	unsigned char key[32];
-	int ret = -EFAULT;
-
-	skcipher = crypto_alloc_skcipher("cbc-aes-aesni", 0, 0);
-	if (IS_ERR(skcipher)) {
-		pr_info("could not allocate skcipher handle\n");
-		return PTR_ERR(skcipher);
-	}
-
-	req = skcipher_request_alloc(skcipher, GFP_KERNEL);
-	if (!req) {
-		pr_info("could not allocate skcipher request\n");
-		ret = -ENOMEM;
-		goto out;
-	}
-
-	skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
-				      test_skcipher_cb,
-				      &amp;sk.result);
-
-	/* AES 256 with random key */
-	get_random_bytes(&amp;key, 32);
-	if (crypto_skcipher_setkey(skcipher, key, 32)) {
-		pr_info("key could not be set\n");
-		ret = -EAGAIN;
-		goto out;
-	}
-
-	/* IV will be random */
-	ivdata = kmalloc(16, GFP_KERNEL);
-	if (!ivdata) {
-		pr_info("could not allocate ivdata\n");
-		goto out;
-	}
-	get_random_bytes(ivdata, 16);
-
-	/* Input data will be random */
-	scratchpad = kmalloc(16, GFP_KERNEL);
-	if (!scratchpad) {
-		pr_info("could not allocate scratchpad\n");
-		goto out;
-	}
-	get_random_bytes(scratchpad, 16);
-
-	sk.tfm = skcipher;
-	sk.req = req;
-
-	/* We encrypt one block */
-	sg_init_one(&amp;sk.sg, scratchpad, 16);
-	skcipher_request_set_crypt(req, &amp;sk.sg, &amp;sk.sg, 16, ivdata);
-	init_completion(&amp;sk.result.completion);
-
-	/* encrypt data */
-	ret = test_skcipher_encdec(&amp;sk, 1);
-	if (ret)
-		goto out;
-
-	pr_info("Encryption triggered successfully\n");
-
-out:
-	if (skcipher)
-		crypto_free_skcipher(skcipher);
-	if (req)
-		skcipher_request_free(req);
-	if (ivdata)
-		kfree(ivdata);
-	if (scratchpad)
-		kfree(scratchpad);
-	return ret;
-}
-    </programlisting>
-   </sect1>
-
-   <sect1><title>Code Example For Use of Operational State Memory With SHASH</title>
-    <programlisting>
-
-struct sdesc {
-	struct shash_desc shash;
-	char ctx[];
-};
-
-static struct sdescinit_sdesc(struct crypto_shash *alg)
-{
-	struct sdescsdesc;
-	int size;
-
-	size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
-	sdesc = kmalloc(size, GFP_KERNEL);
-	if (!sdesc)
-		return ERR_PTR(-ENOMEM);
-	sdesc-&gt;shash.tfm = alg;
-	sdesc-&gt;shash.flags = 0x0;
-	return sdesc;
-}
-
-static int calc_hash(struct crypto_shashalg,
-		     const unsigned chardata, unsigned int datalen,
-		     unsigned chardigest) {
-	struct sdescsdesc;
-	int ret;
-
-	sdesc = init_sdesc(alg);
-	if (IS_ERR(sdesc)) {
-		pr_info("trusted_key: can't alloc %s\n", hash_alg);
-		return PTR_ERR(sdesc);
-	}
-
-	ret = crypto_shash_digest(&amp;sdesc-&gt;shash, data, datalen, digest);
-	kfree(sdesc);
-	return ret;
-}
-    </programlisting>
-   </sect1>
-
-   <sect1><title>Code Example For Random Number Generator Usage</title>
-    <programlisting>
-
-static int get_random_numbers(u8 *buf, unsigned int len)
-{
-	struct crypto_rngrng = NULL;
-	chardrbg = "drbg_nopr_sha256"; /* Hash DRBG with SHA-256, no PR */
-	int ret;
-
-	if (!buf || !len) {
-		pr_debug("No output buffer provided\n");
-		return -EINVAL;
-	}
-
-	rng = crypto_alloc_rng(drbg, 0, 0);
-	if (IS_ERR(rng)) {
-		pr_debug("could not allocate RNG handle for %s\n", drbg);
-		return -PTR_ERR(rng);
-	}
-
-	ret = crypto_rng_get_bytes(rng, buf, len);
-	if (ret &lt; 0)
-		pr_debug("generation of random numbers failed\n");
-	else if (ret == 0)
-		pr_debug("RNG returned no data");
-	else
-		pr_debug("RNG returned %d bytes of data\n", ret);
-
-out:
-	crypto_free_rng(rng);
-	return ret;
-}
-    </programlisting>
-   </sect1>
-  </chapter>
- </book>

Documentation/crypto/api-aead.rst

@@ -0,0 +1,23 @@
+Authenticated Encryption With Associated Data (AEAD) Algorithm Definitions
+--------------------------------------------------------------------------
+
+.. kernel-doc:: include/crypto/aead.h
+   :doc: Authenticated Encryption With Associated Data (AEAD) Cipher API
+
+.. kernel-doc:: include/crypto/aead.h
+   :functions: aead_request aead_alg
+
+Authenticated Encryption With Associated Data (AEAD) Cipher API
+---------------------------------------------------------------
+
+.. kernel-doc:: include/crypto/aead.h
+   :functions: crypto_alloc_aead crypto_free_aead crypto_aead_ivsize crypto_aead_authsize crypto_aead_blocksize crypto_aead_setkey crypto_aead_setauthsize crypto_aead_encrypt crypto_aead_decrypt
+
+Asynchronous AEAD Request Handle
+--------------------------------
+
+.. kernel-doc:: include/crypto/aead.h
+   :doc: Asynchronous AEAD Request Handle
+
+.. kernel-doc:: include/crypto/aead.h
+   :functions: crypto_aead_reqsize aead_request_set_tfm aead_request_alloc aead_request_free aead_request_set_callback aead_request_set_crypt aead_request_set_ad

Documentation/crypto/api-akcipher.rst

@@ -0,0 +1,20 @@
+Asymmetric Cipher Algorithm Definitions
+---------------------------------------
+
+.. kernel-doc:: include/crypto/akcipher.h
+   :functions: akcipher_alg akcipher_request
+
+Asymmetric Cipher API
+---------------------
+
+.. kernel-doc:: include/crypto/akcipher.h
+   :doc: Generic Public Key API
+
+.. kernel-doc:: include/crypto/akcipher.h
+   :functions: crypto_alloc_akcipher crypto_free_akcipher crypto_akcipher_set_pub_key crypto_akcipher_set_priv_key crypto_akcipher_maxsize crypto_akcipher_encrypt crypto_akcipher_decrypt crypto_akcipher_sign crypto_akcipher_verify
+
+Asymmetric Cipher Request Handle
+--------------------------------
+
+.. kernel-doc:: include/crypto/akcipher.h
+   :functions: akcipher_request_alloc akcipher_request_free akcipher_request_set_callback akcipher_request_set_crypt

Documentation/crypto/api-digest.rst

@@ -0,0 +1,35 @@
+Message Digest Algorithm Definitions
+------------------------------------
+
+.. kernel-doc:: include/crypto/hash.h
+   :doc: Message Digest Algorithm Definitions
+
+.. kernel-doc:: include/crypto/hash.h
+   :functions: hash_alg_common ahash_alg shash_alg
+
+Asynchronous Message Digest API
+-------------------------------
+
+.. kernel-doc:: include/crypto/hash.h
+   :doc: Asynchronous Message Digest API
+
+.. kernel-doc:: include/crypto/hash.h
+   :functions: crypto_alloc_ahash crypto_free_ahash crypto_ahash_init crypto_ahash_digestsize crypto_ahash_reqtfm crypto_ahash_reqsize crypto_ahash_setkey crypto_ahash_finup crypto_ahash_final crypto_ahash_digest crypto_ahash_export crypto_ahash_import
+
+Asynchronous Hash Request Handle
+--------------------------------
+
+.. kernel-doc:: include/crypto/hash.h
+   :doc: Asynchronous Hash Request Handle
+
+.. kernel-doc:: include/crypto/hash.h
+   :functions: ahash_request_set_tfm ahash_request_alloc ahash_request_free ahash_request_set_callback ahash_request_set_crypt
+
+Synchronous Message Digest API
+------------------------------
+
+.. kernel-doc:: include/crypto/hash.h
+   :doc: Synchronous Message Digest API
+
+.. kernel-doc:: include/crypto/hash.h
+   :functions: crypto_alloc_shash crypto_free_shash crypto_shash_blocksize crypto_shash_digestsize crypto_shash_descsize crypto_shash_setkey crypto_shash_digest crypto_shash_export crypto_shash_import crypto_shash_init crypto_shash_update crypto_shash_final crypto_shash_finup

Documentation/crypto/api-kpp.rst

@@ -0,0 +1,38 @@
+Key-agreement Protocol Primitives (KPP) Cipher Algorithm Definitions
+--------------------------------------------------------------------
+
+.. kernel-doc:: include/crypto/kpp.h
+   :functions: kpp_request crypto_kpp kpp_alg kpp_secret
+
+Key-agreement Protocol Primitives (KPP) Cipher API
+--------------------------------------------------
+
+.. kernel-doc:: include/crypto/kpp.h
+   :doc: Generic Key-agreement Protocol Primitives API
+
+.. kernel-doc:: include/crypto/kpp.h
+   :functions: crypto_alloc_kpp crypto_free_kpp crypto_kpp_set_secret crypto_kpp_generate_public_key crypto_kpp_compute_shared_secret crypto_kpp_maxsize
+
+Key-agreement Protocol Primitives (KPP) Cipher Request Handle
+-------------------------------------------------------------
+
+.. kernel-doc:: include/crypto/kpp.h
+   :functions: kpp_request_alloc kpp_request_free kpp_request_set_callback kpp_request_set_input kpp_request_set_output
+
+ECDH Helper Functions
+---------------------
+
+.. kernel-doc:: include/crypto/ecdh.h
+   :doc: ECDH Helper Functions
+
+.. kernel-doc:: include/crypto/ecdh.h
+   :functions: ecdh crypto_ecdh_key_len crypto_ecdh_encode_key crypto_ecdh_decode_key
+
+DH Helper Functions
+-------------------
+
+.. kernel-doc:: include/crypto/dh.h
+   :doc: DH Helper Functions
+
+.. kernel-doc:: include/crypto/dh.h
+   :functions: dh crypto_dh_key_len crypto_dh_encode_key crypto_dh_decode_key

Documentation/crypto/api-rng.rst

@@ -0,0 +1,14 @@
+Random Number Algorithm Definitions
+-----------------------------------
+
+.. kernel-doc:: include/crypto/rng.h
+   :functions: rng_alg
+
+Crypto API Random Number API
+----------------------------
+
+.. kernel-doc:: include/crypto/rng.h
+   :doc: Random number generator API
+
+.. kernel-doc:: include/crypto/rng.h
+   :functions: crypto_alloc_rng crypto_rng_alg crypto_free_rng crypto_rng_generate crypto_rng_get_bytes crypto_rng_reset crypto_rng_seedsize

Documentation/crypto/api-samples.rst

@@ -0,0 +1,224 @@
+Code Examples
+=============
+
+Code Example For Symmetric Key Cipher Operation
+-----------------------------------------------
+
+::
+
+
+    struct tcrypt_result {
+        struct completion completion;
+        int err;
+    };
+
+    /* tie all data structures together */
+    struct skcipher_def {
+        struct scatterlist sg;
+        struct crypto_skcipher *tfm;
+        struct skcipher_request *req;
+        struct tcrypt_result result;
+    };
+
+    /* Callback function */
+    static void test_skcipher_cb(struct crypto_async_request *req, int error)
+    {
+        struct tcrypt_result *result = req->data;
+
+        if (error == -EINPROGRESS)
+            return;
+        result->err = error;
+        complete(&result->completion);
+        pr_info("Encryption finished successfully\n");
+    }
+
+    /* Perform cipher operation */
+    static unsigned int test_skcipher_encdec(struct skcipher_def *sk,
+                         int enc)
+    {
+        int rc = 0;
+
+        if (enc)
+            rc = crypto_skcipher_encrypt(sk->req);
+        else
+            rc = crypto_skcipher_decrypt(sk->req);
+
+        switch (rc) {
+        case 0:
+            break;
+        case -EINPROGRESS:
+        case -EBUSY:
+            rc = wait_for_completion_interruptible(
+                &sk->result.completion);
+            if (!rc && !sk->result.err) {
+                reinit_completion(&sk->result.completion);
+                break;
+            }
+        default:
+            pr_info("skcipher encrypt returned with %d result %d\n",
+                rc, sk->result.err);
+            break;
+        }
+        init_completion(&sk->result.completion);
+
+        return rc;
+    }
+
+    /* Initialize and trigger cipher operation */
+    static int test_skcipher(void)
+    {
+        struct skcipher_def sk;
+        struct crypto_skcipher *skcipher = NULL;
+        struct skcipher_request *req = NULL;
+        char *scratchpad = NULL;
+        char *ivdata = NULL;
+        unsigned char key[32];
+        int ret = -EFAULT;
+
+        skcipher = crypto_alloc_skcipher("cbc-aes-aesni", 0, 0);
+        if (IS_ERR(skcipher)) {
+            pr_info("could not allocate skcipher handle\n");
+            return PTR_ERR(skcipher);
+        }
+
+        req = skcipher_request_alloc(skcipher, GFP_KERNEL);
+        if (!req) {
+            pr_info("could not allocate skcipher request\n");
+            ret = -ENOMEM;
+            goto out;
+        }
+
+        skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+                          test_skcipher_cb,
+                          &sk.result);
+
+        /* AES 256 with random key */
+        get_random_bytes(&key, 32);
+        if (crypto_skcipher_setkey(skcipher, key, 32)) {
+            pr_info("key could not be set\n");
+            ret = -EAGAIN;
+            goto out;
+        }
+
+        /* IV will be random */
+        ivdata = kmalloc(16, GFP_KERNEL);
+        if (!ivdata) {
+            pr_info("could not allocate ivdata\n");
+            goto out;
+        }
+        get_random_bytes(ivdata, 16);
+
+        /* Input data will be random */
+        scratchpad = kmalloc(16, GFP_KERNEL);
+        if (!scratchpad) {
+            pr_info("could not allocate scratchpad\n");
+            goto out;
+        }
+        get_random_bytes(scratchpad, 16);
+
+        sk.tfm = skcipher;
+        sk.req = req;
+
+        /* We encrypt one block */
+        sg_init_one(&sk.sg, scratchpad, 16);
+        skcipher_request_set_crypt(req, &sk.sg, &sk.sg, 16, ivdata);
+        init_completion(&sk.result.completion);
+
+        /* encrypt data */
+        ret = test_skcipher_encdec(&sk, 1);
+        if (ret)
+            goto out;
+
+        pr_info("Encryption triggered successfully\n");
+
+    out:
+        if (skcipher)
+            crypto_free_skcipher(skcipher);
+        if (req)
+            skcipher_request_free(req);
+        if (ivdata)
+            kfree(ivdata);
+        if (scratchpad)
+            kfree(scratchpad);
+        return ret;
+    }
+
+
+Code Example For Use of Operational State Memory With SHASH
+-----------------------------------------------------------
+
+::
+
+
+    struct sdesc {
+        struct shash_desc shash;
+        char ctx[];
+    };
+
+    static struct sdescinit_sdesc(struct crypto_shash *alg)
+    {
+        struct sdescsdesc;
+        int size;
+
+        size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
+        sdesc = kmalloc(size, GFP_KERNEL);
+        if (!sdesc)
+            return ERR_PTR(-ENOMEM);
+        sdesc->shash.tfm = alg;
+        sdesc->shash.flags = 0x0;
+        return sdesc;
+    }
+
+    static int calc_hash(struct crypto_shashalg,
+                 const unsigned chardata, unsigned int datalen,
+                 unsigned chardigest) {
+        struct sdescsdesc;
+        int ret;
+
+        sdesc = init_sdesc(alg);
+        if (IS_ERR(sdesc)) {
+            pr_info("trusted_key: can't alloc %s\n", hash_alg);
+            return PTR_ERR(sdesc);
+        }
+
+        ret = crypto_shash_digest(&sdesc->shash, data, datalen, digest);
+        kfree(sdesc);
+        return ret;
+    }
+
+
+Code Example For Random Number Generator Usage
+----------------------------------------------
+
+::
+
+
+    static int get_random_numbers(u8 *buf, unsigned int len)
+    {
+        struct crypto_rngrng = NULL;
+        chardrbg = "drbg_nopr_sha256"; /* Hash DRBG with SHA-256, no PR */
+        int ret;
+
+        if (!buf || !len) {
+            pr_debug("No output buffer provided\n");
+            return -EINVAL;
+        }
+
+        rng = crypto_alloc_rng(drbg, 0, 0);
+        if (IS_ERR(rng)) {
+            pr_debug("could not allocate RNG handle for %s\n", drbg);
+            return -PTR_ERR(rng);
+        }
+
+        ret = crypto_rng_get_bytes(rng, buf, len);
+        if (ret < 0)
+            pr_debug("generation of random numbers failed\n");
+        else if (ret == 0)
+            pr_debug("RNG returned no data");
+        else
+            pr_debug("RNG returned %d bytes of data\n", ret);
+
+    out:
+        crypto_free_rng(rng);
+        return ret;
+    }

Documentation/crypto/api-skcipher.rst

@@ -0,0 +1,62 @@
+Block Cipher Algorithm Definitions
+----------------------------------
+
+.. kernel-doc:: include/linux/crypto.h
+   :doc: Block Cipher Algorithm Definitions
+
+.. kernel-doc:: include/linux/crypto.h
+   :functions: crypto_alg ablkcipher_alg blkcipher_alg cipher_alg
+
+Symmetric Key Cipher API
+------------------------
+
+.. kernel-doc:: include/crypto/skcipher.h
+   :doc: Symmetric Key Cipher API
+
+.. kernel-doc:: include/crypto/skcipher.h
+   :functions: crypto_alloc_skcipher crypto_free_skcipher crypto_has_skcipher crypto_skcipher_ivsize crypto_skcipher_blocksize crypto_skcipher_setkey crypto_skcipher_reqtfm crypto_skcipher_encrypt crypto_skcipher_decrypt
+
+Symmetric Key Cipher Request Handle
+-----------------------------------
+
+.. kernel-doc:: include/crypto/skcipher.h
+   :doc: Symmetric Key Cipher Request Handle
+
+.. kernel-doc:: include/crypto/skcipher.h
+   :functions: crypto_skcipher_reqsize skcipher_request_set_tfm skcipher_request_alloc skcipher_request_free skcipher_request_set_callback skcipher_request_set_crypt
+
+Single Block Cipher API
+-----------------------
+
+.. kernel-doc:: include/linux/crypto.h
+   :doc: Single Block Cipher API
+
+.. kernel-doc:: include/linux/crypto.h
+   :functions: crypto_alloc_cipher crypto_free_cipher crypto_has_cipher crypto_cipher_blocksize crypto_cipher_setkey crypto_cipher_encrypt_one crypto_cipher_decrypt_one
+
+Asynchronous Block Cipher API - Deprecated
+------------------------------------------
+
+.. kernel-doc:: include/linux/crypto.h
+   :doc: Asynchronous Block Cipher API
+
+.. kernel-doc:: include/linux/crypto.h
+   :functions: crypto_free_ablkcipher crypto_has_ablkcipher crypto_ablkcipher_ivsize crypto_ablkcipher_blocksize crypto_ablkcipher_setkey crypto_ablkcipher_reqtfm crypto_ablkcipher_encrypt crypto_ablkcipher_decrypt
+
+Asynchronous Cipher Request Handle - Deprecated
+-----------------------------------------------
+
+.. kernel-doc:: include/linux/crypto.h
+   :doc: Asynchronous Cipher Request Handle
+
+.. kernel-doc:: include/linux/crypto.h
+   :functions: crypto_ablkcipher_reqsize ablkcipher_request_set_tfm ablkcipher_request_alloc ablkcipher_request_free ablkcipher_request_set_callback ablkcipher_request_set_crypt
+
+Synchronous Block Cipher API - Deprecated
+-----------------------------------------
+
+.. kernel-doc:: include/linux/crypto.h
+   :doc: Synchronous Block Cipher API
+
+.. kernel-doc:: include/linux/crypto.h
+   :functions: crypto_alloc_blkcipher rypto_free_blkcipher crypto_has_blkcipher crypto_blkcipher_name crypto_blkcipher_ivsize crypto_blkcipher_blocksize crypto_blkcipher_setkey crypto_blkcipher_encrypt crypto_blkcipher_encrypt_iv crypto_blkcipher_decrypt crypto_blkcipher_decrypt_iv crypto_blkcipher_set_iv crypto_blkcipher_get_iv

Documentation/crypto/api.rst

@@ -0,0 +1,25 @@
+Programming Interface
+=====================
+
+Please note that the kernel crypto API contains the AEAD givcrypt API
+(crypto_aead_giv\* and aead_givcrypt\* function calls in
+include/crypto/aead.h). This API is obsolete and will be removed in the
+future. To obtain the functionality of an AEAD cipher with internal IV
+generation, use the IV generator as a regular cipher. For example,
+rfc4106(gcm(aes)) is the AEAD cipher with external IV generation and
+seqniv(rfc4106(gcm(aes))) implies that the kernel crypto API generates
+the IV. Different IV generators are available.
+
+.. class:: toc-title
+
+	   Table of contents
+
+.. toctree::
+   :maxdepth: 2
+
+   api-skcipher
+   api-aead
+   api-digest
+   api-rng
+   api-akcipher
+   api-kpp

Documentation/crypto/architecture.rst

@@ -0,0 +1,441 @@
+Kernel Crypto API Architecture
+==============================
+
+Cipher algorithm types
+----------------------
+
+The kernel crypto API provides different API calls for the following
+cipher types:
+
+-  Symmetric ciphers
+
+-  AEAD ciphers
+
+-  Message digest, including keyed message digest
+
+-  Random number generation
+
+-  User space interface
+
+Ciphers And Templates
+---------------------
+
+The kernel crypto API provides implementations of single block ciphers
+and message digests. In addition, the kernel crypto API provides
+numerous "templates" that can be used in conjunction with the single
+block ciphers and message digests. Templates include all types of block
+chaining mode, the HMAC mechanism, etc.
+
+Single block ciphers and message digests can either be directly used by
+a caller or invoked together with a template to form multi-block ciphers
+or keyed message digests.
+
+A single block cipher may even be called with multiple templates.
+However, templates cannot be used without a single cipher.
+
+See /proc/crypto and search for "name". For example:
+
+-  aes
+
+-  ecb(aes)
+
+-  cmac(aes)
+
+-  ccm(aes)
+
+-  rfc4106(gcm(aes))
+
+-  sha1
+
+-  hmac(sha1)
+
+-  authenc(hmac(sha1),cbc(aes))
+
+In these examples, "aes" and "sha1" are the ciphers and all others are
+the templates.
+
+Synchronous And Asynchronous Operation
+--------------------------------------
+
+The kernel crypto API provides synchronous and asynchronous API
+operations.
+
+When using the synchronous API operation, the caller invokes a cipher
+operation which is performed synchronously by the kernel crypto API.
+That means, the caller waits until the cipher operation completes.
+Therefore, the kernel crypto API calls work like regular function calls.
+For synchronous operation, the set of API calls is small and
+conceptually similar to any other crypto library.
+
+Asynchronous operation is provided by the kernel crypto API which
+implies that the invocation of a cipher operation will complete almost
+instantly. That invocation triggers the cipher operation but it does not
+signal its completion. Before invoking a cipher operation, the caller
+must provide a callback function the kernel crypto API can invoke to
+signal the completion of the cipher operation. Furthermore, the caller
+must ensure it can handle such asynchronous events by applying
+appropriate locking around its data. The kernel crypto API does not
+perform any special serialization operation to protect the caller's data
+integrity.
+
+Crypto API Cipher References And Priority
+-----------------------------------------
+
+A cipher is referenced by the caller with a string. That string has the
+following semantics:
+
+::
+
+        template(single block cipher)
+
+
+where "template" and "single block cipher" is the aforementioned
+template and single block cipher, respectively. If applicable,
+additional templates may enclose other templates, such as
+
+::
+
+        template1(template2(single block cipher)))
+
+
+The kernel crypto API may provide multiple implementations of a template
+or a single block cipher. For example, AES on newer Intel hardware has
+the following implementations: AES-NI, assembler implementation, or
+straight C. Now, when using the string "aes" with the kernel crypto API,
+which cipher implementation is used? The answer to that question is the
+priority number assigned to each cipher implementation by the kernel
+crypto API. When a caller uses the string to refer to a cipher during
+initialization of a cipher handle, the kernel crypto API looks up all
+implementations providing an implementation with that name and selects
+the implementation with the highest priority.
+
+Now, a caller may have the need to refer to a specific cipher
+implementation and thus does not want to rely on the priority-based
+selection. To accommodate this scenario, the kernel crypto API allows
+the cipher implementation to register a unique name in addition to
+common names. When using that unique name, a caller is therefore always
+sure to refer to the intended cipher implementation.
+
+The list of available ciphers is given in /proc/crypto. However, that
+list does not specify all possible permutations of templates and
+ciphers. Each block listed in /proc/crypto may contain the following
+information -- if one of the components listed as follows are not
+applicable to a cipher, it is not displayed:
+
+-  name: the generic name of the cipher that is subject to the
+   priority-based selection -- this name can be used by the cipher
+   allocation API calls (all names listed above are examples for such
+   generic names)
+
+-  driver: the unique name of the cipher -- this name can be used by the
+   cipher allocation API calls
+
+-  module: the kernel module providing the cipher implementation (or
+   "kernel" for statically linked ciphers)
+
+-  priority: the priority value of the cipher implementation
+
+-  refcnt: the reference count of the respective cipher (i.e. the number
+   of current consumers of this cipher)
+
+-  selftest: specification whether the self test for the cipher passed
+
+-  type:
+
+   -  skcipher for symmetric key ciphers
+
+   -  cipher for single block ciphers that may be used with an
+      additional template
+
+   -  shash for synchronous message digest
+
+   -  ahash for asynchronous message digest
+
+   -  aead for AEAD cipher type
+
+   -  compression for compression type transformations
+
+   -  rng for random number generator
+
+   -  givcipher for cipher with associated IV generator (see the geniv
+      entry below for the specification of the IV generator type used by
+      the cipher implementation)
+
+   -  kpp for a Key-agreement Protocol Primitive (KPP) cipher such as
+      an ECDH or DH implementation
+
+-  blocksize: blocksize of cipher in bytes
+
+-  keysize: key size in bytes
+
+-  ivsize: IV size in bytes
+
+-  seedsize: required size of seed data for random number generator
+
+-  digestsize: output size of the message digest
+
+-  geniv: IV generation type:
+
+   -  eseqiv for encrypted sequence number based IV generation
+
+   -  seqiv for sequence number based IV generation
+
+   -  chainiv for chain iv generation
+
+   -  <builtin> is a marker that the cipher implements IV generation and
+      handling as it is specific to the given cipher
+
+Key Sizes
+---------
+
+When allocating a cipher handle, the caller only specifies the cipher
+type. Symmetric ciphers, however, typically support multiple key sizes
+(e.g. AES-128 vs. AES-192 vs. AES-256). These key sizes are determined
+with the length of the provided key. Thus, the kernel crypto API does
+not provide a separate way to select the particular symmetric cipher key
+size.
+
+Cipher Allocation Type And Masks
+--------------------------------
+
+The different cipher handle allocation functions allow the specification
+of a type and mask flag. Both parameters have the following meaning (and
+are therefore not covered in the subsequent sections).
+
+The type flag specifies the type of the cipher algorithm. The caller
+usually provides a 0 when the caller wants the default handling.
+Otherwise, the caller may provide the following selections which match
+the aforementioned cipher types:
+
+-  CRYPTO_ALG_TYPE_CIPHER Single block cipher
+
+-  CRYPTO_ALG_TYPE_COMPRESS Compression
+
+-  CRYPTO_ALG_TYPE_AEAD Authenticated Encryption with Associated Data
+   (MAC)
+
+-  CRYPTO_ALG_TYPE_BLKCIPHER Synchronous multi-block cipher
+
+-  CRYPTO_ALG_TYPE_ABLKCIPHER Asynchronous multi-block cipher
+
+-  CRYPTO_ALG_TYPE_GIVCIPHER Asynchronous multi-block cipher packed
+   together with an IV generator (see geniv field in the /proc/crypto
+   listing for the known IV generators)
+
+-  CRYPTO_ALG_TYPE_KPP Key-agreement Protocol Primitive (KPP) such as
+   an ECDH or DH implementation
+
+-  CRYPTO_ALG_TYPE_DIGEST Raw message digest
+
+-  CRYPTO_ALG_TYPE_HASH Alias for CRYPTO_ALG_TYPE_DIGEST
+
+-  CRYPTO_ALG_TYPE_SHASH Synchronous multi-block hash
+
+-  CRYPTO_ALG_TYPE_AHASH Asynchronous multi-block hash
+
+-  CRYPTO_ALG_TYPE_RNG Random Number Generation
+
+-  CRYPTO_ALG_TYPE_AKCIPHER Asymmetric cipher
+
+-  CRYPTO_ALG_TYPE_PCOMPRESS Enhanced version of
+   CRYPTO_ALG_TYPE_COMPRESS allowing for segmented compression /
+   decompression instead of performing the operation on one segment
+   only. CRYPTO_ALG_TYPE_PCOMPRESS is intended to replace
+   CRYPTO_ALG_TYPE_COMPRESS once existing consumers are converted.
+
+The mask flag restricts the type of cipher. The only allowed flag is
+CRYPTO_ALG_ASYNC to restrict the cipher lookup function to
+asynchronous ciphers. Usually, a caller provides a 0 for the mask flag.
+
+When the caller provides a mask and type specification, the caller
+limits the search the kernel crypto API can perform for a suitable
+cipher implementation for the given cipher name. That means, even when a
+caller uses a cipher name that exists during its initialization call,
+the kernel crypto API may not select it due to the used type and mask
+field.
+
+Internal Structure of Kernel Crypto API
+---------------------------------------
+
+The kernel crypto API has an internal structure where a cipher
+implementation may use many layers and indirections. This section shall
+help to clarify how the kernel crypto API uses various components to
+implement the complete cipher.
+
+The following subsections explain the internal structure based on
+existing cipher implementations. The first section addresses the most
+complex scenario where all other scenarios form a logical subset.
+
+Generic AEAD Cipher Structure
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following ASCII art decomposes the kernel crypto API layers when
+using the AEAD cipher with the automated IV generation. The shown
+example is used by the IPSEC layer.
+
+For other use cases of AEAD ciphers, the ASCII art applies as well, but
+the caller may not use the AEAD cipher with a separate IV generator. In
+this case, the caller must generate the IV.
+
+The depicted example decomposes the AEAD cipher of GCM(AES) based on the
+generic C implementations (gcm.c, aes-generic.c, ctr.c, ghash-generic.c,
+seqiv.c). The generic implementation serves as an example showing the
+complete logic of the kernel crypto API.
+
+It is possible that some streamlined cipher implementations (like
+AES-NI) provide implementations merging aspects which in the view of the
+kernel crypto API cannot be decomposed into layers any more. In case of
+the AES-NI implementation, the CTR mode, the GHASH implementation and
+the AES cipher are all merged into one cipher implementation registered
+with the kernel crypto API. In this case, the concept described by the
+following ASCII art applies too. However, the decomposition of GCM into
+the individual sub-components by the kernel crypto API is not done any
+more.
+
+Each block in the following ASCII art is an independent cipher instance
+obtained from the kernel crypto API. Each block is accessed by the
+caller or by other blocks using the API functions defined by the kernel
+crypto API for the cipher implementation type.
+
+The blocks below indicate the cipher type as well as the specific logic
+implemented in the cipher.
+
+The ASCII art picture also indicates the call structure, i.e. who calls
+which component. The arrows point to the invoked block where the caller
+uses the API applicable to the cipher type specified for the block.
+
+::
+
+
+    kernel crypto API                                |   IPSEC Layer
+                                                     |
+    +-----------+                                    |
+    |           |            (1)
+    |   aead    | <-----------------------------------  esp_output
+    |  (seqiv)  | ---+
+    +-----------+    |
+                     | (2)
+    +-----------+    |
+    |           | <--+                (2)
+    |   aead    | <-----------------------------------  esp_input
+    |   (gcm)   | ------------+
+    +-----------+             |
+          | (3)               | (5)
+          v                   v
+    +-----------+       +-----------+
+    |           |       |           |
+    |  skcipher |       |   ahash   |
+    |   (ctr)   | ---+  |  (ghash)  |
+    +-----------+    |  +-----------+
+                     |
+    +-----------+    | (4)
+    |           | <--+
+    |   cipher  |
+    |   (aes)   |
+    +-----------+
+
+
+
+The following call sequence is applicable when the IPSEC layer triggers
+an encryption operation with the esp_output function. During
+configuration, the administrator set up the use of rfc4106(gcm(aes)) as
+the cipher for ESP. The following call sequence is now depicted in the
+ASCII art above:
+
+1. esp_output() invokes crypto_aead_encrypt() to trigger an
+   encryption operation of the AEAD cipher with IV generator.
+
+   In case of GCM, the SEQIV implementation is registered as GIVCIPHER
+   in crypto_rfc4106_alloc().
+
+   The SEQIV performs its operation to generate an IV where the core
+   function is seqiv_geniv().
+
+2. Now, SEQIV uses the AEAD API function calls to invoke the associated
+   AEAD cipher. In our case, during the instantiation of SEQIV, the
+   cipher handle for GCM is provided to SEQIV. This means that SEQIV
+   invokes AEAD cipher operations with the GCM cipher handle.
+
+   During instantiation of the GCM handle, the CTR(AES) and GHASH
+   ciphers are instantiated. The cipher handles for CTR(AES) and GHASH
+   are retained for later use.
+
+   The GCM implementation is responsible to invoke the CTR mode AES and
+   the GHASH cipher in the right manner to implement the GCM
+   specification.
+
+3. The GCM AEAD cipher type implementation now invokes the SKCIPHER API
+   with the instantiated CTR(AES) cipher handle.
+
+   During instantiation of the CTR(AES) cipher, the CIPHER type
+   implementation of AES is instantiated. The cipher handle for AES is
+   retained.
+
+   That means that the SKCIPHER implementation of CTR(AES) only
+   implements the CTR block chaining mode. After performing the block
+   chaining operation, the CIPHER implementation of AES is invoked.
+
+4. The SKCIPHER of CTR(AES) now invokes the CIPHER API with the AES
+   cipher handle to encrypt one block.
+
+5. The GCM AEAD implementation also invokes the GHASH cipher
+   implementation via the AHASH API.
+
+When the IPSEC layer triggers the esp_input() function, the same call
+sequence is followed with the only difference that the operation starts
+with step (2).
+
+Generic Block Cipher Structure
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Generic block ciphers follow the same concept as depicted with the ASCII
+art picture above.
+
+For example, CBC(AES) is implemented with cbc.c, and aes-generic.c. The
+ASCII art picture above applies as well with the difference that only
+step (4) is used and the SKCIPHER block chaining mode is CBC.
+
+Generic Keyed Message Digest Structure
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Keyed message digest implementations again follow the same concept as
+depicted in the ASCII art picture above.
+
+For example, HMAC(SHA256) is implemented with hmac.c and
+sha256_generic.c. The following ASCII art illustrates the
+implementation:
+
+::
+
+
+    kernel crypto API            |       Caller
+                                 |
+    +-----------+         (1)    |
+    |           | <------------------  some_function
+    |   ahash   |
+    |   (hmac)  | ---+
+    +-----------+    |
+                     | (2)
+    +-----------+    |
+    |           | <--+
+    |   shash   |
+    |  (sha256) |
+    +-----------+
+
+
+
+The following call sequence is applicable when a caller triggers an HMAC
+operation:
+
+1. The AHASH API functions are invoked by the caller. The HMAC
+   implementation performs its operation as needed.
+
+   During initialization of the HMAC cipher, the SHASH cipher type of
+   SHA256 is instantiated. The cipher handle for the SHA256 instance is
+   retained.
+
+   At one time, the HMAC implementation requires a SHA256 operation
+   where the SHA256 cipher handle is used.
+
+2. The HMAC instance now invokes the SHASH API with the SHA256 cipher
+   handle to calculate the message digest.

Documentation/crypto/devel-algos.rst

@@ -0,0 +1,247 @@
+Developing Cipher Algorithms
+============================
+
+Registering And Unregistering Transformation
+--------------------------------------------
+
+There are three distinct types of registration functions in the Crypto
+API. One is used to register a generic cryptographic transformation,
+while the other two are specific to HASH transformations and
+COMPRESSion. We will discuss the latter two in a separate chapter, here
+we will only look at the generic ones.
+
+Before discussing the register functions, the data structure to be
+filled with each, struct crypto_alg, must be considered -- see below
+for a description of this data structure.
+
+The generic registration functions can be found in
+include/linux/crypto.h and their definition can be seen below. The
+former function registers a single transformation, while the latter
+works on an array of transformation descriptions. The latter is useful
+when registering transformations in bulk, for example when a driver
+implements multiple transformations.
+
+::
+
+       int crypto_register_alg(struct crypto_alg *alg);
+       int crypto_register_algs(struct crypto_alg *algs, int count);
+
+
+The counterparts to those functions are listed below.
+
+::
+
+       int crypto_unregister_alg(struct crypto_alg *alg);
+       int crypto_unregister_algs(struct crypto_alg *algs, int count);
+
+
+Notice that both registration and unregistration functions do return a
+value, so make sure to handle errors. A return code of zero implies
+success. Any return code < 0 implies an error.
+
+The bulk registration/unregistration functions register/unregister each
+transformation in the given array of length count. They handle errors as
+follows:
+
+-  crypto_register_algs() succeeds if and only if it successfully
+   registers all the given transformations. If an error occurs partway
+   through, then it rolls back successful registrations before returning
+   the error code. Note that if a driver needs to handle registration
+   errors for individual transformations, then it will need to use the
+   non-bulk function crypto_register_alg() instead.
+
+-  crypto_unregister_algs() tries to unregister all the given
+   transformations, continuing on error. It logs errors and always
+   returns zero.
+
+Single-Block Symmetric Ciphers [CIPHER]
+---------------------------------------
+
+Example of transformations: aes, arc4, ...
+
+This section describes the simplest of all transformation
+implementations, that being the CIPHER type used for symmetric ciphers.
+The CIPHER type is used for transformations which operate on exactly one
+block at a time and there are no dependencies between blocks at all.
+
+Registration specifics
+~~~~~~~~~~~~~~~~~~~~~~
+
+The registration of [CIPHER] algorithm is specific in that struct
+crypto_alg field .cra_type is empty. The .cra_u.cipher has to be
+filled in with proper callbacks to implement this transformation.
+
+See struct cipher_alg below.
+
+Cipher Definition With struct cipher_alg
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Struct cipher_alg defines a single block cipher.
+
+Here are schematics of how these functions are called when operated from
+other part of the kernel. Note that the .cia_setkey() call might happen
+before or after any of these schematics happen, but must not happen
+during any of these are in-flight.
+
+::
+
+             KEY ---.    PLAINTEXT ---.
+                    v                 v
+              .cia_setkey() -> .cia_encrypt()
+                                      |
+                                      '-----> CIPHERTEXT
+
+
+Please note that a pattern where .cia_setkey() is called multiple times
+is also valid:
+
+::
+
+
+      KEY1 --.    PLAINTEXT1 --.         KEY2 --.    PLAINTEXT2 --.
+             v                 v                v                 v
+       .cia_setkey() -> .cia_encrypt() -> .cia_setkey() -> .cia_encrypt()
+                               |                                  |
+                               '---> CIPHERTEXT1                  '---> CIPHERTEXT2
+
+
+Multi-Block Ciphers
+-------------------
+
+Example of transformations: cbc(aes), ecb(arc4), ...
+
+This section describes the multi-block cipher transformation
+implementations. The multi-block ciphers are used for transformations
+which operate on scatterlists of data supplied to the transformation
+functions. They output the result into a scatterlist of data as well.
+
+Registration Specifics
+~~~~~~~~~~~~~~~~~~~~~~
+
+The registration of multi-block cipher algorithms is one of the most
+standard procedures throughout the crypto API.
+
+Note, if a cipher implementation requires a proper alignment of data,
+the caller should use the functions of crypto_skcipher_alignmask() to
+identify a memory alignment mask. The kernel crypto API is able to
+process requests that are unaligned. This implies, however, additional
+overhead as the kernel crypto API needs to perform the realignment of
+the data which may imply moving of data.
+
+Cipher Definition With struct blkcipher_alg and ablkcipher_alg
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Struct blkcipher_alg defines a synchronous block cipher whereas struct
+ablkcipher_alg defines an asynchronous block cipher.
+
+Please refer to the single block cipher description for schematics of
+the block cipher usage.
+
+Specifics Of Asynchronous Multi-Block Cipher
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+There are a couple of specifics to the asynchronous interface.
+
+First of all, some of the drivers will want to use the Generic
+ScatterWalk in case the hardware needs to be fed separate chunks of the
+scatterlist which contains the plaintext and will contain the
+ciphertext. Please refer to the ScatterWalk interface offered by the
+Linux kernel scatter / gather list implementation.
+
+Hashing [HASH]
+--------------
+
+Example of transformations: crc32, md5, sha1, sha256,...
+
+Registering And Unregistering The Transformation
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+There are multiple ways to register a HASH transformation, depending on
+whether the transformation is synchronous [SHASH] or asynchronous
+[AHASH] and the amount of HASH transformations we are registering. You
+can find the prototypes defined in include/crypto/internal/hash.h:
+
+::
+
+       int crypto_register_ahash(struct ahash_alg *alg);
+
+       int crypto_register_shash(struct shash_alg *alg);
+       int crypto_register_shashes(struct shash_alg *algs, int count);
+
+
+The respective counterparts for unregistering the HASH transformation
+are as follows:
+
+::
+
+       int crypto_unregister_ahash(struct ahash_alg *alg);
+
+       int crypto_unregister_shash(struct shash_alg *alg);
+       int crypto_unregister_shashes(struct shash_alg *algs, int count);
+
+
+Cipher Definition With struct shash_alg and ahash_alg
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Here are schematics of how these functions are called when operated from
+other part of the kernel. Note that the .setkey() call might happen
+before or after any of these schematics happen, but must not happen
+during any of these are in-flight. Please note that calling .init()
+followed immediately by .finish() is also a perfectly valid
+transformation.
+
+::
+
+       I)   DATA -----------.
+                            v
+             .init() -> .update() -> .final()      ! .update() might not be called
+                         ^    |         |            at all in this scenario.
+                         '----'         '---> HASH
+
+       II)  DATA -----------.-----------.
+                            v           v
+             .init() -> .update() -> .finup()      ! .update() may not be called
+                         ^    |         |            at all in this scenario.
+                         '----'         '---> HASH
+
+       III) DATA -----------.
+                            v
+                        .digest()                  ! The entire process is handled
+                            |                        by the .digest() call.
+                            '---------------> HASH
+
+
+Here is a schematic of how the .export()/.import() functions are called
+when used from another part of the kernel.
+
+::
+
+       KEY--.                 DATA--.
+            v                       v                  ! .update() may not be called
+        .setkey() -> .init() -> .update() -> .export()   at all in this scenario.
+                                 ^     |         |
+                                 '-----'         '--> PARTIAL_HASH
+
+       ----------- other transformations happen here -----------
+
+       PARTIAL_HASH--.   DATA1--.
+                     v          v
+                 .import -> .update() -> .final()     ! .update() may not be called
+                             ^    |         |           at all in this scenario.
+                             '----'         '--> HASH1
+
+       PARTIAL_HASH--.   DATA2-.
+                     v         v
+                 .import -> .finup()
+                               |
+                               '---------------> HASH2
+
+
+Specifics Of Asynchronous HASH Transformation
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Some of the drivers will want to use the Generic ScatterWalk in case the
+implementation needs to be fed separate chunks of the scatterlist which
+contains the input data. The buffer containing the resulting hash will
+always be properly aligned to .cra_alignmask so there is no need to
+worry about this.

Documentation/crypto/index.rst

@@ -0,0 +1,24 @@
+=======================
+Linux Kernel Crypto API
+=======================
+
+:Author: Stephan Mueller
+:Author: Marek Vasut
+
+This documentation outlines the Linux kernel crypto API with its
+concepts, details about developing cipher implementations, employment of the API
+for cryptographic use cases, as well as programming examples.
+
+.. class:: toc-title
+
+	   Table of contents
+
+.. toctree::
+   :maxdepth: 2
+
+   intro
+   architecture
+   devel-algos
+   userspace-if
+   api
+   api-samples

Documentation/crypto/intro.rst

@@ -0,0 +1,74 @@
+Kernel Crypto API Interface Specification
+=========================================
+
+Introduction
+------------
+
+The kernel crypto API offers a rich set of cryptographic ciphers as well
+as other data transformation mechanisms and methods to invoke these.
+This document contains a description of the API and provides example
+code.
+
+To understand and properly use the kernel crypto API a brief explanation
+of its structure is given. Based on the architecture, the API can be
+separated into different components. Following the architecture
+specification, hints to developers of ciphers are provided. Pointers to
+the API function call documentation are given at the end.
+
+The kernel crypto API refers to all algorithms as "transformations".
+Therefore, a cipher handle variable usually has the name "tfm". Besides
+cryptographic operations, the kernel crypto API also knows compression
+transformations and handles them the same way as ciphers.
+
+The kernel crypto API serves the following entity types:
+
+-  consumers requesting cryptographic services
+
+-  data transformation implementations (typically ciphers) that can be
+   called by consumers using the kernel crypto API
+
+This specification is intended for consumers of the kernel crypto API as
+well as for developers implementing ciphers. This API specification,
+however, does not discuss all API calls available to data transformation
+implementations (i.e. implementations of ciphers and other
+transformations (such as CRC or even compression algorithms) that can
+register with the kernel crypto API).
+
+Note: The terms "transformation" and cipher algorithm are used
+interchangeably.
+
+Terminology
+-----------
+
+The transformation implementation is an actual code or interface to
+hardware which implements a certain transformation with precisely
+defined behavior.
+
+The transformation object (TFM) is an instance of a transformation
+implementation. There can be multiple transformation objects associated
+with a single transformation implementation. Each of those
+transformation objects is held by a crypto API consumer or another
+transformation. Transformation object is allocated when a crypto API
+consumer requests a transformation implementation. The consumer is then
+provided with a structure, which contains a transformation object (TFM).
+
+The structure that contains transformation objects may also be referred
+to as a "cipher handle". Such a cipher handle is always subject to the
+following phases that are reflected in the API calls applicable to such
+a cipher handle:
+
+1. Initialization of a cipher handle.
+
+2. Execution of all intended cipher operations applicable for the handle
+   where the cipher handle must be furnished to every API call.
+
+3. Destruction of a cipher handle.
+
+When using the initialization API calls, a cipher handle is created and
+returned to the consumer. Therefore, please refer to all initialization
+API calls that refer to the data structure type a consumer is expected
+to receive and subsequently to use. The initialization API calls have
+all the same naming conventions of crypto_alloc\*.
+
+The transformation context is private data associated with the
+transformation object.

Documentation/crypto/userspace-if.rst

@@ -0,0 +1,387 @@
+User Space Interface
+====================
+
+Introduction
+------------
+
+The concepts of the kernel crypto API visible to kernel space is fully
+applicable to the user space interface as well. Therefore, the kernel
+crypto API high level discussion for the in-kernel use cases applies
+here as well.
+
+The major difference, however, is that user space can only act as a
+consumer and never as a provider of a transformation or cipher
+algorithm.
+
+The following covers the user space interface exported by the kernel
+crypto API. A working example of this description is libkcapi that can
+be obtained from [1]. That library can be used by user space
+applications that require cryptographic services from the kernel.
+
+Some details of the in-kernel kernel crypto API aspects do not apply to
+user space, however. This includes the difference between synchronous
+and asynchronous invocations. The user space API call is fully
+synchronous.
+
+[1] http://www.chronox.de/libkcapi.html
+
+User Space API General Remarks
+------------------------------
+
+The kernel crypto API is accessible from user space. Currently, the
+following ciphers are accessible:
+
+-  Message digest including keyed message digest (HMAC, CMAC)
+
+-  Symmetric ciphers
+
+-  AEAD ciphers
+
+-  Random Number Generators
+
+The interface is provided via socket type using the type AF_ALG. In
+addition, the setsockopt option type is SOL_ALG. In case the user space
+header files do not export these flags yet, use the following macros:
+
+::
+
+    #ifndef AF_ALG
+    #define AF_ALG 38
+    #endif
+    #ifndef SOL_ALG
+    #define SOL_ALG 279
+    #endif
+
+
+A cipher is accessed with the same name as done for the in-kernel API
+calls. This includes the generic vs. unique naming schema for ciphers as
+well as the enforcement of priorities for generic names.
+
+To interact with the kernel crypto API, a socket must be created by the
+user space application. User space invokes the cipher operation with the
+send()/write() system call family. The result of the cipher operation is
+obtained with the read()/recv() system call family.
+
+The following API calls assume that the socket descriptor is already
+opened by the user space application and discusses only the kernel
+crypto API specific invocations.
+
+To initialize the socket interface, the following sequence has to be
+performed by the consumer:
+
+1. Create a socket of type AF_ALG with the struct sockaddr_alg
+   parameter specified below for the different cipher types.
+
+2. Invoke bind with the socket descriptor
+
+3. Invoke accept with the socket descriptor. The accept system call
+   returns a new file descriptor that is to be used to interact with the
+   particular cipher instance. When invoking send/write or recv/read
+   system calls to send data to the kernel or obtain data from the
+   kernel, the file descriptor returned by accept must be used.
+
+In-place Cipher operation
+-------------------------
+
+Just like the in-kernel operation of the kernel crypto API, the user
+space interface allows the cipher operation in-place. That means that
+the input buffer used for the send/write system call and the output
+buffer used by the read/recv system call may be one and the same. This
+is of particular interest for symmetric cipher operations where a
+copying of the output data to its final destination can be avoided.
+
+If a consumer on the other hand wants to maintain the plaintext and the
+ciphertext in different memory locations, all a consumer needs to do is
+to provide different memory pointers for the encryption and decryption
+operation.
+
+Message Digest API
+------------------
+
+The message digest type to be used for the cipher operation is selected
+when invoking the bind syscall. bind requires the caller to provide a
+filled struct sockaddr data structure. This data structure must be
+filled as follows:
+
+::
+
+    struct sockaddr_alg sa = {
+        .salg_family = AF_ALG,
+        .salg_type = "hash", /* this selects the hash logic in the kernel */
+        .salg_name = "sha1" /* this is the cipher name */
+    };
+
+
+The salg_type value "hash" applies to message digests and keyed message
+digests. Though, a keyed message digest is referenced by the appropriate
+salg_name. Please see below for the setsockopt interface that explains
+how the key can be set for a keyed message digest.
+
+Using the send() system call, the application provides the data that
+should be processed with the message digest. The send system call allows
+the following flags to be specified:
+
+-  MSG_MORE: If this flag is set, the send system call acts like a
+   message digest update function where the final hash is not yet
+   calculated. If the flag is not set, the send system call calculates
+   the final message digest immediately.
+
+With the recv() system call, the application can read the message digest
+from the kernel crypto API. If the buffer is too small for the message
+digest, the flag MSG_TRUNC is set by the kernel.
+
+In order to set a message digest key, the calling application must use
+the setsockopt() option of ALG_SET_KEY. If the key is not set the HMAC
+operation is performed without the initial HMAC state change caused by
+the key.
+
+Symmetric Cipher API
+--------------------
+
+The operation is very similar to the message digest discussion. During
+initialization, the struct sockaddr data structure must be filled as
+follows:
+
+::
+
+    struct sockaddr_alg sa = {
+        .salg_family = AF_ALG,
+        .salg_type = "skcipher", /* this selects the symmetric cipher */
+        .salg_name = "cbc(aes)" /* this is the cipher name */
+    };
+
+
+Before data can be sent to the kernel using the write/send system call
+family, the consumer must set the key. The key setting is described with
+the setsockopt invocation below.
+
+Using the sendmsg() system call, the application provides the data that
+should be processed for encryption or decryption. In addition, the IV is
+specified with the data structure provided by the sendmsg() system call.
+
+The sendmsg system call parameter of struct msghdr is embedded into the
+struct cmsghdr data structure. See recv(2) and cmsg(3) for more
+information on how the cmsghdr data structure is used together with the
+send/recv system call family. That cmsghdr data structure holds the
+following information specified with a separate header instances:
+
+-  specification of the cipher operation type with one of these flags:
+
+   -  ALG_OP_ENCRYPT - encryption of data
+
+   -  ALG_OP_DECRYPT - decryption of data
+
+-  specification of the IV information marked with the flag ALG_SET_IV
+
+The send system call family allows the following flag to be specified:
+
+-  MSG_MORE: If this flag is set, the send system call acts like a
+   cipher update function where more input data is expected with a
+   subsequent invocation of the send system call.
+
+Note: The kernel reports -EINVAL for any unexpected data. The caller
+must make sure that all data matches the constraints given in
+/proc/crypto for the selected cipher.
+
+With the recv() system call, the application can read the result of the
+cipher operation from the kernel crypto API. The output buffer must be
+at least as large as to hold all blocks of the encrypted or decrypted
+data. If the output data size is smaller, only as many blocks are
+returned that fit into that output buffer size.
+
+AEAD Cipher API
+---------------
+
+The operation is very similar to the symmetric cipher discussion. During
+initialization, the struct sockaddr data structure must be filled as
+follows:
+
+::
+
+    struct sockaddr_alg sa = {
+        .salg_family = AF_ALG,
+        .salg_type = "aead", /* this selects the symmetric cipher */
+        .salg_name = "gcm(aes)" /* this is the cipher name */
+    };
+
+
+Before data can be sent to the kernel using the write/send system call
+family, the consumer must set the key. The key setting is described with
+the setsockopt invocation below.
+
+In addition, before data can be sent to the kernel using the write/send
+system call family, the consumer must set the authentication tag size.
+To set the authentication tag size, the caller must use the setsockopt
+invocation described below.
+
+Using the sendmsg() system call, the application provides the data that
+should be processed for encryption or decryption. In addition, the IV is
+specified with the data structure provided by the sendmsg() system call.
+
+The sendmsg system call parameter of struct msghdr is embedded into the
+struct cmsghdr data structure. See recv(2) and cmsg(3) for more
+information on how the cmsghdr data structure is used together with the
+send/recv system call family. That cmsghdr data structure holds the
+following information specified with a separate header instances:
+
+-  specification of the cipher operation type with one of these flags:
+
+   -  ALG_OP_ENCRYPT - encryption of data
+
+   -  ALG_OP_DECRYPT - decryption of data
+
+-  specification of the IV information marked with the flag ALG_SET_IV
+
+-  specification of the associated authentication data (AAD) with the
+   flag ALG_SET_AEAD_ASSOCLEN. The AAD is sent to the kernel together
+   with the plaintext / ciphertext. See below for the memory structure.
+
+The send system call family allows the following flag to be specified:
+
+-  MSG_MORE: If this flag is set, the send system call acts like a
+   cipher update function where more input data is expected with a
+   subsequent invocation of the send system call.
+
+Note: The kernel reports -EINVAL for any unexpected data. The caller
+must make sure that all data matches the constraints given in
+/proc/crypto for the selected cipher.
+
+With the recv() system call, the application can read the result of the
+cipher operation from the kernel crypto API. The output buffer must be
+at least as large as defined with the memory structure below. If the
+output data size is smaller, the cipher operation is not performed.
+
+The authenticated decryption operation may indicate an integrity error.
+Such breach in integrity is marked with the -EBADMSG error code.
+
+AEAD Memory Structure
+~~~~~~~~~~~~~~~~~~~~~
+
+The AEAD cipher operates with the following information that is
+communicated between user and kernel space as one data stream:
+
+-  plaintext or ciphertext
+
+-  associated authentication data (AAD)
+
+-  authentication tag
+
+The sizes of the AAD and the authentication tag are provided with the
+sendmsg and setsockopt calls (see there). As the kernel knows the size
+of the entire data stream, the kernel is now able to calculate the right
+offsets of the data components in the data stream.
+
+The user space caller must arrange the aforementioned information in the
+following order:
+
+-  AEAD encryption input: AAD \|\| plaintext
+
+-  AEAD decryption input: AAD \|\| ciphertext \|\| authentication tag
+
+The output buffer the user space caller provides must be at least as
+large to hold the following data:
+
+-  AEAD encryption output: ciphertext \|\| authentication tag
+
+-  AEAD decryption output: plaintext
+
+Random Number Generator API
+---------------------------
+
+Again, the operation is very similar to the other APIs. During
+initialization, the struct sockaddr data structure must be filled as
+follows:
+
+::
+
+    struct sockaddr_alg sa = {
+        .salg_family = AF_ALG,
+        .salg_type = "rng", /* this selects the symmetric cipher */
+        .salg_name = "drbg_nopr_sha256" /* this is the cipher name */
+    };
+
+
+Depending on the RNG type, the RNG must be seeded. The seed is provided
+using the setsockopt interface to set the key. For example, the
+ansi_cprng requires a seed. The DRBGs do not require a seed, but may be
+seeded.
+
+Using the read()/recvmsg() system calls, random numbers can be obtained.
+The kernel generates at most 128 bytes in one call. If user space
+requires more data, multiple calls to read()/recvmsg() must be made.
+
+WARNING: The user space caller may invoke the initially mentioned accept
+system call multiple times. In this case, the returned file descriptors
+have the same state.
+
+Zero-Copy Interface
+-------------------
+
+In addition to the send/write/read/recv system call family, the AF_ALG
+interface can be accessed with the zero-copy interface of
+splice/vmsplice. As the name indicates, the kernel tries to avoid a copy
+operation into kernel space.
+
+The zero-copy operation requires data to be aligned at the page
+boundary. Non-aligned data can be used as well, but may require more
+operations of the kernel which would defeat the speed gains obtained
+from the zero-copy interface.
+
+The system-interent limit for the size of one zero-copy operation is 16
+pages. If more data is to be sent to AF_ALG, user space must slice the
+input into segments with a maximum size of 16 pages.
+
+Zero-copy can be used with the following code example (a complete
+working example is provided with libkcapi):
+
+::
+
+    int pipes[2];
+
+    pipe(pipes);
+    /* input data in iov */
+    vmsplice(pipes[1], iov, iovlen, SPLICE_F_GIFT);
+    /* opfd is the file descriptor returned from accept() system call */
+    splice(pipes[0], NULL, opfd, NULL, ret, 0);
+    read(opfd, out, outlen);
+
+
+Setsockopt Interface
+--------------------
+
+In addition to the read/recv and send/write system call handling to send
+and retrieve data subject to the cipher operation, a consumer also needs
+to set the additional information for the cipher operation. This
+additional information is set using the setsockopt system call that must
+be invoked with the file descriptor of the open cipher (i.e. the file
+descriptor returned by the accept system call).
+
+Each setsockopt invocation must use the level SOL_ALG.
+
+The setsockopt interface allows setting the following data using the
+mentioned optname:
+
+-  ALG_SET_KEY -- Setting the key. Key setting is applicable to:
+
+   -  the skcipher cipher type (symmetric ciphers)
+
+   -  the hash cipher type (keyed message digests)
+
+   -  the AEAD cipher type
+
+   -  the RNG cipher type to provide the seed
+
+-  ALG_SET_AEAD_AUTHSIZE -- Setting the authentication tag size for
+   AEAD ciphers. For a encryption operation, the authentication tag of
+   the given size will be generated. For a decryption operation, the
+   provided ciphertext is assumed to contain an authentication tag of
+   the given size (see section about AEAD memory layout below).
+
+User space API example
+----------------------
+
+Please see [1] for libkcapi which provides an easy-to-use wrapper around
+the aforementioned Netlink kernel interface. [1] also contains a test
+application that invokes all libkcapi API calls.
+
+[1] http://www.chronox.de/libkcapi.html

Documentation/index.rst

@@ -58,6 +58,7 @@ needed).
    gpu/index
    security/index
    sound/index
+   crypto/index
 
 Korean translations
 -------------------

crypto/algif_aead.c

@@ -556,18 +556,8 @@ static int aead_recvmsg_sync(struct socket *sock, struct msghdr *msg, int flags)
 	lock_sock(sk);
 
 	/*
-	 * AEAD memory structure: For encryption, the tag is appended to the
-	 * ciphertext which implies that the memory allocated for the ciphertext
-	 * must be increased by the tag length. For decryption, the tag
-	 * is expected to be concatenated to the ciphertext. The plaintext
-	 * therefore has a memory size of the ciphertext minus the tag length.
-	 *
-	 * The memory structure for cipher operation has the following
-	 * structure:
-	 *	AEAD encryption input:  assoc data || plaintext
-	 *	AEAD encryption output: cipherntext || auth tag
-	 *	AEAD decryption input:  assoc data || ciphertext || auth tag
-	 *	AEAD decryption output: plaintext
+	 * Please see documentation of aead_request_set_crypt for the
+	 * description of the AEAD memory structure expected from the caller.
 	 */
 
 	if (ctx->more) {

include/crypto/aead.h

@@ -55,14 +55,14 @@
  * The scatter list pointing to the input data must contain:
  *
  * * for RFC4106 ciphers, the concatenation of
- * associated authentication data || IV || plaintext or ciphertext. Note, the
- * same IV (buffer) is also set with the aead_request_set_crypt call. Note,
- * the API call of aead_request_set_ad must provide the length of the AAD and
- * the IV. The API call of aead_request_set_crypt only points to the size of
- * the input plaintext or ciphertext.
+ *   associated authentication data || IV || plaintext or ciphertext. Note, the
+ *   same IV (buffer) is also set with the aead_request_set_crypt call. Note,
+ *   the API call of aead_request_set_ad must provide the length of the AAD and
+ *   the IV. The API call of aead_request_set_crypt only points to the size of
+ *   the input plaintext or ciphertext.
  *
  * * for "normal" AEAD ciphers, the concatenation of
- * associated authentication data || plaintext or ciphertext.
+ *   associated authentication data || plaintext or ciphertext.
  *
  * It is important to note that if multiple scatter gather list entries form
  * the input data mentioned above, the first entry must not point to a NULL
@@ -452,7 +452,7 @@ static inline void aead_request_free(struct aead_request *req)
  * completes
  *
  * The callback function is registered with the aead_request handle and
- * must comply with the following template
+ * must comply with the following template::
  *
  *	void callback_function(struct crypto_async_request *req, int error)
  */
@@ -483,30 +483,18 @@ static inline void aead_request_set_callback(struct aead_request *req,
  * destination is the ciphertext. For a decryption operation, the use is
  * reversed - the source is the ciphertext and the destination is the plaintext.
  *
- * For both src/dst the layout is associated data, plain/cipher text,
- * authentication tag.
- *
- * The content of the AD in the destination buffer after processing
- * will either be untouched, or it will contain a copy of the AD
- * from the source buffer.  In order to ensure that it always has
- * a copy of the AD, the user must copy the AD over either before
- * or after processing.  Of course this is not relevant if the user
- * is doing in-place processing where src == dst.
- *
- * IMPORTANT NOTE AEAD requires an authentication tag (MAC). For decryption,
- *		  the caller must concatenate the ciphertext followed by the
- *		  authentication tag and provide the entire data stream to the
- *		  decryption operation (i.e. the data length used for the
- *		  initialization of the scatterlist and the data length for the
- *		  decryption operation is identical). For encryption, however,
- *		  the authentication tag is created while encrypting the data.
- *		  The destination buffer must hold sufficient space for the
- *		  ciphertext and the authentication tag while the encryption
- *		  invocation must only point to the plaintext data size. The
- *		  following code snippet illustrates the memory usage
- *		  buffer = kmalloc(ptbuflen + (enc ? authsize : 0));
- *		  sg_init_one(&sg, buffer, ptbuflen + (enc ? authsize : 0));
- *		  aead_request_set_crypt(req, &sg, &sg, ptbuflen, iv);
+ * The memory structure for cipher operation has the following structure:
+ *
+ * - AEAD encryption input:  assoc data || plaintext
+ * - AEAD encryption output: assoc data || cipherntext || auth tag
+ * - AEAD decryption input:  assoc data || ciphertext || auth tag
+ * - AEAD decryption output: assoc data || plaintext
+ *
+ * Albeit the kernel requires the presence of the AAD buffer, however,
+ * the kernel does not fill the AAD buffer in the output case. If the
+ * caller wants to have that data buffer filled, the caller must either
+ * use an in-place cipher operation (i.e. same memory location for
+ * input/output memory location).
  */
 static inline void aead_request_set_crypt(struct aead_request *req,
 					  struct scatterlist *src,

include/crypto/dh.h

@@ -13,6 +13,27 @@
 #ifndef _CRYPTO_DH_
 #define _CRYPTO_DH_
 
+/**
+ * DOC: DH Helper Functions
+ *
+ * To use DH with the KPP cipher API, the following data structure and
+ * functions should be used.
+ *
+ * To use DH with KPP, the following functions should be used to operate on
+ * a DH private key. The packet private key that can be set with
+ * the KPP API function call of crypto_kpp_set_secret.
+ */
+
+/**
+ * struct dh - define a DH private key
+ *
+ * @key:	Private DH key
+ * @p:		Diffie-Hellman parameter P
+ * @g:		Diffie-Hellman generator G
+ * @key_size:	Size of the private DH key
+ * @p_size:	Size of DH parameter P
+ * @g_size:	Size of DH generator G
+ */
 struct dh {
 	void *key;
 	void *p;
@@ -22,8 +43,45 @@ struct dh {
 	unsigned int g_size;
 };
 
+/**
+ * crypto_dh_key_len() - Obtain the size of the private DH key
+ * @params:	private DH key
+ *
+ * This function returns the packet DH key size. A caller can use that
+ * with the provided DH private key reference to obtain the required
+ * memory size to hold a packet key.
+ *
+ * Return: size of the key in bytes
+ */
 int crypto_dh_key_len(const struct dh *params);
+
+/**
+ * crypto_dh_encode_key() - encode the private key
+ * @buf:	Buffer allocated by the caller to hold the packet DH
+ *		private key. The buffer should be at least crypto_dh_key_len
+ *		bytes in size.
+ * @len:	Length of the packet private key buffer
+ * @params:	Buffer with the caller-specified private key
+ *
+ * The DH implementations operate on a packet representation of the private
+ * key.
+ *
+ * Return:	-EINVAL if buffer has insufficient size, 0 on success
+ */
 int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params);
+
+/**
+ * crypto_dh_decode_key() - decode a private key
+ * @buf:	Buffer holding a packet key that should be decoded
+ * @len:	Lenth of the packet private key buffer
+ * @params:	Buffer allocated by the caller that is filled with the
+ *		unpacket DH private key.
+ *
+ * The unpacking obtains the private key by pointing @p to the correct location
+ * in @buf. Thus, both pointers refer to the same memory.
+ *
+ * Return:	-EINVAL if buffer has insufficient size, 0 on success
+ */
 int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params);
 
 #endif

include/crypto/ecdh.h

@@ -13,18 +13,76 @@
 #ifndef _CRYPTO_ECDH_
 #define _CRYPTO_ECDH_
 
+/**
+ * DOC: ECDH Helper Functions
+ *
+ * To use ECDH with the KPP cipher API, the following data structure and
+ * functions should be used.
+ *
+ * The ECC curves known to the ECDH implementation are specified in this
+ * header file.
+ *
+ * To use ECDH with KPP, the following functions should be used to operate on
+ * an ECDH private key. The packet private key that can be set with
+ * the KPP API function call of crypto_kpp_set_secret.
+ */
+
 /* Curves IDs */
 #define ECC_CURVE_NIST_P192	0x0001
 #define ECC_CURVE_NIST_P256	0x0002
 
+/**
+ * struct ecdh - define an ECDH private key
+ *
+ * @curve_id:	ECC curve the key is based on.
+ * @key:	Private ECDH key
+ * @key_size:	Size of the private ECDH key
+ */
 struct ecdh {
 	unsigned short curve_id;
 	char *key;
 	unsigned short key_size;
 };
 
+/**
+ * crypto_ecdh_key_len() - Obtain the size of the private ECDH key
+ * @params:	private ECDH key
+ *
+ * This function returns the packet ECDH key size. A caller can use that
+ * with the provided ECDH private key reference to obtain the required
+ * memory size to hold a packet key.
+ *
+ * Return: size of the key in bytes
+ */
 int crypto_ecdh_key_len(const struct ecdh *params);
+
+/**
+ * crypto_ecdh_encode_key() - encode the private key
+ * @buf:	Buffer allocated by the caller to hold the packet ECDH
+ *		private key. The buffer should be at least crypto_ecdh_key_len
+ *		bytes in size.
+ * @len:	Length of the packet private key buffer
+ * @p:		Buffer with the caller-specified private key
+ *
+ * The ECDH implementations operate on a packet representation of the private
+ * key.
+ *
+ * Return:	-EINVAL if buffer has insufficient size, 0 on success
+ */
 int crypto_ecdh_encode_key(char *buf, unsigned int len, const struct ecdh *p);
+
+/**
+ * crypto_ecdh_decode_key() - decode a private key
+ * @buf:	Buffer holding a packet key that should be decoded
+ * @len:	Lenth of the packet private key buffer
+ * @p:		Buffer allocated by the caller that is filled with the
+ *		unpacket ECDH private key.
+ *
+ * The unpacking obtains the private key by pointing @p to the correct location
+ * in @buf. Thus, both pointers refer to the same memory.
+ *
+ * Return:	-EINVAL if buffer has insufficient size, 0 on success
+ */
 int crypto_ecdh_decode_key(const char *buf, unsigned int len, struct ecdh *p);
 
 #endif

include/crypto/hash.h

@@ -605,7 +605,7 @@ static inline struct ahash_request *ahash_request_cast(
  * the cipher operation completes.
  *
  * The callback function is registered with the &ahash_request handle and
- * must comply with the following template
+ * must comply with the following template::
  *
  *	void callback_function(struct crypto_async_request *req, int error)
  */

include/crypto/kpp.h

@@ -71,7 +71,7 @@ struct crypto_kpp {
  *
  * @reqsize:		Request context size required by algorithm
  *			implementation
- * @base		Common crypto API algorithm data structure
+ * @base:		Common crypto API algorithm data structure
  */
 struct kpp_alg {
 	int (*set_secret)(struct crypto_kpp *tfm, void *buffer,
@@ -89,7 +89,7 @@ struct kpp_alg {
 };
 
 /**
- * DOC: Generic Key-agreement Protocol Primitevs API
+ * DOC: Generic Key-agreement Protocol Primitives API
  *
  * The KPP API is used with the algorithm type
  * CRYPTO_ALG_TYPE_KPP (listed as type "kpp" in /proc/crypto)
@@ -264,6 +264,12 @@ struct kpp_secret {
  * Function invokes the specific kpp operation for a given alg.
  *
  * @tfm:	tfm handle
+ * @buffer:	Buffer holding the packet representation of the private
+ *		key. The structure of the packet key depends on the particular
+ *		KPP implementation. Packing and unpacking helpers are provided
+ *		for ECDH and DH (see the respective header files for those
+ *		implementations).
+ * @len:	Length of the packet private key buffer.
  *
  * Return: zero on success; error code in case of error
  */
@@ -279,7 +285,10 @@ static inline int crypto_kpp_set_secret(struct crypto_kpp *tfm, void *buffer,
  * crypto_kpp_generate_public_key() - Invoke kpp operation
  *
  * Function invokes the specific kpp operation for generating the public part
- * for a given kpp algorithm
+ * for a given kpp algorithm.
+ *
+ * To generate a private key, the caller should use a random number generator.
+ * The output of the requested length serves as the private key.
  *
  * @req:	kpp key request
  *

include/crypto/skcipher.h

@@ -516,7 +516,7 @@ static inline void skcipher_request_zero(struct skcipher_request *req)
  * skcipher_request_set_callback() - set asynchronous callback function
  * @req: request handle
  * @flags: specify zero or an ORing of the flags
- *         CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
+ *	   CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
  *	   increase the wait queue beyond the initial maximum size;
  *	   CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep
  * @compl: callback function pointer to be registered with the request handle
@@ -533,7 +533,7 @@ static inline void skcipher_request_zero(struct skcipher_request *req)
  * cipher operation completes.
  *
  * The callback function is registered with the skcipher_request handle and
- * must comply with the following template
+ * must comply with the following template::
  *
  *	void callback_function(struct crypto_async_request *req, int error)
  */

include/linux/crypto.h

@@ -963,7 +963,7 @@ static inline void ablkcipher_request_free(struct ablkcipher_request *req)
  * ablkcipher_request_set_callback() - set asynchronous callback function
  * @req: request handle
  * @flags: specify zero or an ORing of the flags
- *         CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
+ *	   CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
  *	   increase the wait queue beyond the initial maximum size;
  *	   CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep
  * @compl: callback function pointer to be registered with the request handle
@@ -980,7 +980,7 @@ static inline void ablkcipher_request_free(struct ablkcipher_request *req)
  * cipher operation completes.
  *
  * The callback function is registered with the ablkcipher_request handle and
- * must comply with the following template
+ * must comply with the following template::
  *
  *	void callback_function(struct crypto_async_request *req, int error)
  */