crypto: sha-mb - Fix load failure

On  Monday, February 1, 2016 4:18 PM, Herbert Xu wrote:
>
> On Wed, Jan 27, 2016 at 05:08:35PM +0800, Rui Wang wrote:
>>
>> +static int sha1_mb_async_import(struct ahash_request *req, const void
>> +*in) {
>> +	struct ahash_request *mcryptd_req = ahash_request_ctx(req);
>> +	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
>> +	struct sha1_mb_ctx *ctx = crypto_ahash_ctx(tfm);
>> +	struct mcryptd_ahash *mcryptd_tfm = ctx->mcryptd_tfm;
>> +	struct crypto_shash *child = mcryptd_ahash_child(mcryptd_tfm);
>> +	struct mcryptd_hash_request_ctx *rctx;
>> +	struct shash_desc *desc;
>> +	int err;
>> +
>> +	memcpy(mcryptd_req, req, sizeof(*req));
>> +	ahash_request_set_tfm(mcryptd_req, &mcryptd_tfm->base);
>> +	rctx = ahash_request_ctx(mcryptd_req);
>> +	desc = &rctx->desc;
>> +	desc->tfm = child;
>> +	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
>> +
>> +	err = crypto_shash_init(desc);
>> +	if (err)
>> +		return err;
>
> What is this desc for?

Hi Herbert,

Yeah I just realized that the call to crypto_shash_init() isn't necessary
here. What it does is overwritten by crypto_ahash_import(). But this desc
still needs to be initialized here because it's newly allocated by
ahash_request_alloc(). We eventually calls the shash version of import()
which needs desc as an argument. The real context to be imported is then
derived from shash_desc_ctx(desc).

desc is a sub-field of struct mcryptd_hash_request_ctx, which is again a
sub-field of the bigger blob allocated by ahash_request_alloc(). The entire
blob's size is set in sha1_mb_async_init_tfm(). So a better version is as
follows:

(just removed the call to crypto_shash_init())

>From 4bcb73adbef99aada94c49f352063619aa24d43d Mon Sep 17 00:00:00 2001
From: Rui Wang <rui.y.wang@intel.com>
Date: Mon, 14 Dec 2015 17:22:13 +0800
Subject: [PATCH v2 1/4] crypto x86/sha1_mb: Fix load failure

modprobe sha1_mb fails with the following message:

modprobe: ERROR: could not insert 'sha1_mb': No such device

It is because it needs to set its statesize and implement its
import() and export() interface.

v2: remove redundant call to crypto_shash_init()

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/x86/crypto/sha-mb/sha1_mb.c

@@ -762,6 +762,38 @@ static int sha1_mb_async_digest(struct ahash_request *req)
 	return crypto_ahash_digest(mcryptd_req);
 }
 
+static int sha1_mb_async_export(struct ahash_request *req, void *out)
+{
+	struct ahash_request *mcryptd_req = ahash_request_ctx(req);
+	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
+	struct sha1_mb_ctx *ctx = crypto_ahash_ctx(tfm);
+	struct mcryptd_ahash *mcryptd_tfm = ctx->mcryptd_tfm;
+
+	memcpy(mcryptd_req, req, sizeof(*req));
+	ahash_request_set_tfm(mcryptd_req, &mcryptd_tfm->base);
+	return crypto_ahash_export(mcryptd_req, out);
+}
+
+static int sha1_mb_async_import(struct ahash_request *req, const void *in)
+{
+	struct ahash_request *mcryptd_req = ahash_request_ctx(req);
+	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
+	struct sha1_mb_ctx *ctx = crypto_ahash_ctx(tfm);
+	struct mcryptd_ahash *mcryptd_tfm = ctx->mcryptd_tfm;
+	struct crypto_shash *child = mcryptd_ahash_child(mcryptd_tfm);
+	struct mcryptd_hash_request_ctx *rctx;
+	struct shash_desc *desc;
+
+	memcpy(mcryptd_req, req, sizeof(*req));
+	ahash_request_set_tfm(mcryptd_req, &mcryptd_tfm->base);
+	rctx = ahash_request_ctx(mcryptd_req);
+	desc = &rctx->desc;
+	desc->tfm = child;
+	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+
+	return crypto_ahash_import(mcryptd_req, in);
+}
+
 static int sha1_mb_async_init_tfm(struct crypto_tfm *tfm)
 {
 	struct mcryptd_ahash *mcryptd_tfm;
@@ -796,8 +828,11 @@ static struct ahash_alg sha1_mb_async_alg = {
 	.final          = sha1_mb_async_final,
 	.finup          = sha1_mb_async_finup,
 	.digest         = sha1_mb_async_digest,
+	.export		= sha1_mb_async_export,
+	.import		= sha1_mb_async_import,
 	.halg = {
 		.digestsize     = SHA1_DIGEST_SIZE,
+		.statesize	= sizeof(struct sha1_hash_ctx),
 		.base = {
 			.cra_name               = "sha1",
 			.cra_driver_name        = "sha1_mb",