ext4 crypto: reorganize how we store keys in the inode

This is a pretty massive patch which does a number of different things:

1) The per-inode encryption information is now stored in an allocated
   data structure, ext4_crypt_info, instead of directly in the node.
   This reduces the size usage of an in-memory inode when it is not
   using encryption.

2) We drop the ext4_fname_crypto_ctx entirely, and use the per-inode
   encryption structure instead.  This remove an unnecessary memory
   allocation and free for the fname_crypto_ctx as well as allowing us
   to reuse the ctfm in a directory for multiple lookups and file
   creations.

3) We also cache the inode's policy information in the ext4_crypt_info
   structure so we don't have to continually read it out of the
   extended attributes.

4) We now keep the keyring key in the inode's encryption structure
   instead of releasing it after we are done using it to derive the
   per-inode key.  This allows us to test to see if the key has been
   revoked; if it has, we prevent the use of the derived key and free
   it.

5) When an inode is released (or when the derived key is freed), we
   will use memset_explicit() to zero out the derived key, so it's not
   left hanging around in memory.  This implies that when a user logs
   out, it is important to first revoke the key, and then unlink it,
   and then finally, to use "echo 3 > /proc/sys/vm/drop_caches" to
   release any decrypted pages and dcache entries from the system
   caches.

6) All this, and we also shrink the number of lines of code by around
   100.  :-)

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/crypto.c

@@ -118,8 +118,9 @@ struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode)
 	struct ext4_crypto_ctx *ctx = NULL;
 	int res = 0;
 	unsigned long flags;
-	struct ext4_crypt_info *ci = &EXT4_I(inode)->i_crypt_info;
+	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
 
+	BUG_ON(ci == NULL);
 	if (!ext4_read_workqueue)
 		ext4_init_crypto();
 
@@ -322,7 +323,7 @@ static int ext4_page_crypto(struct ext4_crypto_ctx *ctx,
 	int res = 0;
 
 	BUG_ON(!ctx->tfm);
-	BUG_ON(ctx->mode != ei->i_crypt_info.ci_mode);
+	BUG_ON(ctx->mode != ei->i_crypt_info->ci_mode);
 
 	if (ctx->mode != EXT4_ENCRYPTION_MODE_AES_256_XTS) {
 		printk_ratelimited(KERN_ERR
@@ -334,8 +335,8 @@ static int ext4_page_crypto(struct ext4_crypto_ctx *ctx,
 	crypto_ablkcipher_clear_flags(atfm, ~0);
 	crypto_tfm_set_flags(ctx->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
 
-	res = crypto_ablkcipher_setkey(atfm, ei->i_crypt_info.ci_raw,
-				       ei->i_crypt_info.ci_size);
+	res = crypto_ablkcipher_setkey(atfm, ei->i_crypt_info->ci_raw,
+				       ei->i_crypt_info->ci_size);
 	if (res) {
 		printk_ratelimited(KERN_ERR
 				   "%s: crypto_ablkcipher_setkey() failed\n",

fs/ext4/crypto_fname.c

@@ -48,6 +48,12 @@ bool ext4_valid_filenames_enc_mode(uint32_t mode)
 	return (mode == EXT4_ENCRYPTION_MODE_AES_256_CTS);
 }
 
+static unsigned max_name_len(struct inode *inode)
+{
+	return S_ISLNK(inode->i_mode) ? inode->i_sb->s_blocksize :
+		EXT4_NAME_LEN;
+}
+
 /**
  * ext4_fname_encrypt() -
  *
@@ -55,28 +61,30 @@ bool ext4_valid_filenames_enc_mode(uint32_t mode)
  * ciphertext. Errors are returned as negative numbers.  We trust the caller to
  * allocate sufficient memory to oname string.
  */
-static int ext4_fname_encrypt(struct ext4_fname_crypto_ctx *ctx,
+static int ext4_fname_encrypt(struct inode *inode,
 			      const struct qstr *iname,
 			      struct ext4_str *oname)
 {
 	u32 ciphertext_len;
 	struct ablkcipher_request *req = NULL;
 	DECLARE_EXT4_COMPLETION_RESULT(ecr);
-	struct crypto_ablkcipher *tfm = ctx->ctfm;
+	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
+	struct crypto_ablkcipher *tfm = ci->ci_ctfm;
 	int res = 0;
 	char iv[EXT4_CRYPTO_BLOCK_SIZE];
 	struct scatterlist src_sg, dst_sg;
-	int padding = 4 << (ctx->flags & EXT4_POLICY_FLAGS_PAD_MASK);
+	int padding = 4 << (ci->ci_flags & EXT4_POLICY_FLAGS_PAD_MASK);
 	char *workbuf, buf[32], *alloc_buf = NULL;
+	unsigned lim = max_name_len(inode);
 
-	if (iname->len <= 0 || iname->len > ctx->lim)
+	if (iname->len <= 0 || iname->len > lim)
 		return -EIO;
 
 	ciphertext_len = (iname->len < EXT4_CRYPTO_BLOCK_SIZE) ?
 		EXT4_CRYPTO_BLOCK_SIZE : iname->len;
 	ciphertext_len = ext4_fname_crypto_round_up(ciphertext_len, padding);
-	ciphertext_len = (ciphertext_len > ctx->lim)
-			? ctx->lim : ciphertext_len;
+	ciphertext_len = (ciphertext_len > lim)
+			? lim : ciphertext_len;
 
 	if (ciphertext_len <= sizeof(buf)) {
 		workbuf = buf;
@@ -134,7 +142,7 @@ static int ext4_fname_encrypt(struct ext4_fname_crypto_ctx *ctx,
  *	Errors are returned as negative numbers.
  *	We trust the caller to allocate sufficient memory to oname string.
  */
-static int ext4_fname_decrypt(struct ext4_fname_crypto_ctx *ctx,
+static int ext4_fname_decrypt(struct inode *inode,
 			      const struct ext4_str *iname,
 			      struct ext4_str *oname)
 {
@@ -142,11 +150,13 @@ static int ext4_fname_decrypt(struct ext4_fname_crypto_ctx *ctx,
 	struct ablkcipher_request *req = NULL;
 	DECLARE_EXT4_COMPLETION_RESULT(ecr);
 	struct scatterlist src_sg, dst_sg;
-	struct crypto_ablkcipher *tfm = ctx->ctfm;
+	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
+	struct crypto_ablkcipher *tfm = ci->ci_ctfm;
 	int res = 0;
 	char iv[EXT4_CRYPTO_BLOCK_SIZE];
+	unsigned lim = max_name_len(inode);
 
-	if (iname->len <= 0 || iname->len > ctx->lim)
+	if (iname->len <= 0 || iname->len > lim)
 		return -EIO;
 
 	tmp_in[0].name = iname->name;
@@ -242,171 +252,50 @@ static int digest_decode(const char *src, int len, char *dst)
 	return cp - dst;
 }
 
-/**
- * ext4_free_fname_crypto_ctx() -
- *
- * Frees up a crypto context.
- */
-void ext4_free_fname_crypto_ctx(struct ext4_fname_crypto_ctx *ctx)
-{
-	if (ctx == NULL || IS_ERR(ctx))
-		return;
-
-	if (ctx->ctfm && !IS_ERR(ctx->ctfm))
-		crypto_free_ablkcipher(ctx->ctfm);
-	if (ctx->htfm && !IS_ERR(ctx->htfm))
-		crypto_free_hash(ctx->htfm);
-	kfree(ctx);
-}
-
-/**
- * ext4_put_fname_crypto_ctx() -
- *
- * Return: The crypto context onto free list. If the free list is above a
- * threshold, completely frees up the context, and returns the memory.
- *
- * TODO: Currently we directly free the crypto context. Eventually we should
- * add code it to return to free list. Such an approach will increase
- * efficiency of directory lookup.
- */
-void ext4_put_fname_crypto_ctx(struct ext4_fname_crypto_ctx **ctx)
+int ext4_setup_fname_crypto(struct inode *inode)
 {
-	if (*ctx == NULL || IS_ERR(*ctx))
-		return;
-	ext4_free_fname_crypto_ctx(*ctx);
-	*ctx = NULL;
-}
-
-/**
- * ext4_alloc_fname_crypto_ctx() -
- */
-struct ext4_fname_crypto_ctx *ext4_alloc_fname_crypto_ctx(
-	const struct ext4_crypt_info *ci)
-{
-	struct ext4_fname_crypto_ctx *ctx;
-
-	ctx = kmalloc(sizeof(struct ext4_fname_crypto_ctx), GFP_NOFS);
-	if (ctx == NULL)
-		return ERR_PTR(-ENOMEM);
-	if (ci->ci_mode == EXT4_ENCRYPTION_MODE_INVALID) {
-		/* This will automatically set key mode to invalid
-		 * As enum for ENCRYPTION_MODE_INVALID is zero */
-		memset(&ctx->ci, 0, sizeof(ctx->ci));
-	} else {
-		memcpy(&ctx->ci, ci, sizeof(struct ext4_crypt_info));
-	}
-	ctx->has_valid_key = (EXT4_ENCRYPTION_MODE_INVALID == ci->ci_mode)
-		? 0 : 1;
-	ctx->ctfm_key_is_ready = 0;
-	ctx->ctfm = NULL;
-	ctx->htfm = NULL;
-	return ctx;
-}
-
-/**
- * ext4_get_fname_crypto_ctx() -
- *
- * Allocates a free crypto context and initializes it to hold
- * the crypto material for the inode.
- *
- * Return: NULL if not encrypted. Error value on error. Valid pointer otherwise.
- */
-struct ext4_fname_crypto_ctx *ext4_get_fname_crypto_ctx(
-	struct inode *inode, u32 max_ciphertext_len)
-{
-	struct ext4_fname_crypto_ctx *ctx;
 	struct ext4_inode_info *ei = EXT4_I(inode);
+	struct ext4_crypt_info *ci = ei->i_crypt_info;
+	struct crypto_ablkcipher *ctfm;
 	int res;
 
 	/* Check if the crypto policy is set on the inode */
 	res = ext4_encrypted_inode(inode);
 	if (res == 0)
-		return NULL;
-
-	if (!ext4_has_encryption_key(inode))
-		ext4_generate_encryption_key(inode);
-
-	/* Get a crypto context based on the key. */
-	ctx = ext4_alloc_fname_crypto_ctx(&(ei->i_crypt_info));
-	if (IS_ERR(ctx))
-		return ctx;
-
-	ctx->flags = ei->i_crypt_policy_flags;
-	if (ctx->has_valid_key) {
-		if (ctx->ci.ci_mode != EXT4_ENCRYPTION_MODE_AES_256_CTS) {
-			printk_once(KERN_WARNING
-				    "ext4: unsupported key mode %d\n",
-				    ctx->ci.ci_mode);
-			return ERR_PTR(-ENOKEY);
-		}
+		return 0;
 
-		/* As a first cut, we will allocate new tfm in every call.
-		 * later, we will keep the tfm around, in case the key gets
-		 * re-used */
-		if (ctx->ctfm == NULL) {
-			ctx->ctfm = crypto_alloc_ablkcipher("cts(cbc(aes))",
-					0, 0);
-		}
-		if (IS_ERR(ctx->ctfm)) {
-			res = PTR_ERR(ctx->ctfm);
-			printk(
-			    KERN_DEBUG "%s: error (%d) allocating crypto tfm\n",
-			    __func__, res);
-			ctx->ctfm = NULL;
-			ext4_put_fname_crypto_ctx(&ctx);
-			return ERR_PTR(res);
-		}
-		if (ctx->ctfm == NULL) {
-			printk(
-			    KERN_DEBUG "%s: could not allocate crypto tfm\n",
-			    __func__);
-			ext4_put_fname_crypto_ctx(&ctx);
-			return ERR_PTR(-ENOMEM);
-		}
-		ctx->lim = max_ciphertext_len;
-		crypto_ablkcipher_clear_flags(ctx->ctfm, ~0);
-		crypto_tfm_set_flags(crypto_ablkcipher_tfm(ctx->ctfm),
-			CRYPTO_TFM_REQ_WEAK_KEY);
-
-		/* If we are lucky, we will get a context that is already
-		 * set up with the right key. Else, we will have to
-		 * set the key */
-		if (!ctx->ctfm_key_is_ready) {
-			/* Since our crypto objectives for filename encryption
-			 * are pretty weak,
-			 * we directly use the inode master key */
-			res = crypto_ablkcipher_setkey(ctx->ctfm,
-					ctx->ci.ci_raw, ctx->ci.ci_size);
-			if (res) {
-				ext4_put_fname_crypto_ctx(&ctx);
-				return ERR_PTR(-EIO);
-			}
-			ctx->ctfm_key_is_ready = 1;
-		} else {
-			/* In the current implementation, key should never be
-			 * marked "ready" for a context that has just been
-			 * allocated. So we should never reach here */
-			 BUG();
-		}
-	}
-	if (ctx->htfm == NULL)
-		ctx->htfm = crypto_alloc_hash("sha256", 0, CRYPTO_ALG_ASYNC);
-	if (IS_ERR(ctx->htfm)) {
-		res = PTR_ERR(ctx->htfm);
-		printk(KERN_DEBUG "%s: error (%d) allocating hash tfm\n",
-			__func__, res);
-		ctx->htfm = NULL;
-		ext4_put_fname_crypto_ctx(&ctx);
-		return ERR_PTR(res);
+	res = ext4_get_encryption_info(inode);
+	if (res < 0)
+		return res;
+	ci = ei->i_crypt_info;
+
+	if (!ci || ci->ci_ctfm)
+		return 0;
+
+	if (ci->ci_mode != EXT4_ENCRYPTION_MODE_AES_256_CTS) {
+		printk_once(KERN_WARNING "ext4: unsupported key mode %d\n",
+			    ci->ci_mode);
+		return -ENOKEY;
 	}
-	if (ctx->htfm == NULL) {
-		printk(KERN_DEBUG "%s: could not allocate hash tfm\n",
-				__func__);
-		ext4_put_fname_crypto_ctx(&ctx);
-		return ERR_PTR(-ENOMEM);
+
+	ctfm = crypto_alloc_ablkcipher("cts(cbc(aes))", 0, 0);
+	if (!ctfm || IS_ERR(ctfm)) {
+		res = ctfm ? PTR_ERR(ctfm) : -ENOMEM;
+		printk(KERN_DEBUG "%s: error (%d) allocating crypto tfm\n",
+		       __func__, res);
+		return res;
 	}
+	crypto_ablkcipher_clear_flags(ctfm, ~0);
+	crypto_tfm_set_flags(crypto_ablkcipher_tfm(ctfm),
+			     CRYPTO_TFM_REQ_WEAK_KEY);
 
-	return ctx;
+	res = crypto_ablkcipher_setkey(ctfm, ci->ci_raw, ci->ci_size);
+	if (res) {
+		crypto_free_ablkcipher(ctfm);
+		return -EIO;
+	}
+	ci->ci_ctfm = ctfm;
+	return 0;
 }
 
 /**
@@ -419,41 +308,21 @@ u32 ext4_fname_crypto_round_up(u32 size, u32 blksize)
 	return ((size+blksize-1)/blksize)*blksize;
 }
 
-/**
- * ext4_fname_crypto_namelen_on_disk() -
- */
-int ext4_fname_crypto_namelen_on_disk(struct ext4_fname_crypto_ctx *ctx,
-				      u32 namelen)
-{
-	u32 ciphertext_len;
-	int padding = 4 << (ctx->flags & EXT4_POLICY_FLAGS_PAD_MASK);
-
-	if (ctx == NULL)
-		return -EIO;
-	if (!(ctx->has_valid_key))
-		return -EACCES;
-	ciphertext_len = (namelen < EXT4_CRYPTO_BLOCK_SIZE) ?
-		EXT4_CRYPTO_BLOCK_SIZE : namelen;
-	ciphertext_len = ext4_fname_crypto_round_up(ciphertext_len, padding);
-	ciphertext_len = (ciphertext_len > ctx->lim)
-			? ctx->lim : ciphertext_len;
-	return (int) ciphertext_len;
-}
-
 /**
  * ext4_fname_crypto_alloc_obuff() -
  *
  * Allocates an output buffer that is sufficient for the crypto operation
  * specified by the context and the direction.
  */
-int ext4_fname_crypto_alloc_buffer(struct ext4_fname_crypto_ctx *ctx,
+int ext4_fname_crypto_alloc_buffer(struct inode *inode,
 				   u32 ilen, struct ext4_str *crypto_str)
 {
 	unsigned int olen;
-	int padding = 4 << (ctx->flags & EXT4_POLICY_FLAGS_PAD_MASK);
+	int padding = 16;
+	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
 
-	if (!ctx)
-		return -EIO;
+	if (ci)
+		padding = 4 << (ci->ci_flags & EXT4_POLICY_FLAGS_PAD_MASK);
 	if (padding < EXT4_CRYPTO_BLOCK_SIZE)
 		padding = EXT4_CRYPTO_BLOCK_SIZE;
 	olen = ext4_fname_crypto_round_up(ilen, padding);
@@ -484,7 +353,7 @@ void ext4_fname_crypto_free_buffer(struct ext4_str *crypto_str)
 /**
  * ext4_fname_disk_to_usr() - converts a filename from disk space to user space
  */
-int _ext4_fname_disk_to_usr(struct ext4_fname_crypto_ctx *ctx,
+int _ext4_fname_disk_to_usr(struct inode *inode,
 			    struct dx_hash_info *hinfo,
 			    const struct ext4_str *iname,
 			    struct ext4_str *oname)
@@ -492,8 +361,6 @@ int _ext4_fname_disk_to_usr(struct ext4_fname_crypto_ctx *ctx,
 	char buf[24];
 	int ret;
 
-	if (ctx == NULL)
-		return -EIO;
 	if (iname->len < 3) {
 		/*Check for . and .. */
 		if (iname->name[0] == '.' && iname->name[iname->len-1] == '.') {
@@ -503,8 +370,8 @@ int _ext4_fname_disk_to_usr(struct ext4_fname_crypto_ctx *ctx,
 			return oname->len;
 		}
 	}
-	if (ctx->has_valid_key)
-		return ext4_fname_decrypt(ctx, iname, oname);
+	if (EXT4_I(inode)->i_crypt_info)
+		return ext4_fname_decrypt(inode, iname, oname);
 
 	if (iname->len <= EXT4_FNAME_CRYPTO_DIGEST_SIZE) {
 		ret = digest_encode(iname->name, iname->len, oname->name);
@@ -523,7 +390,7 @@ int _ext4_fname_disk_to_usr(struct ext4_fname_crypto_ctx *ctx,
 	return ret + 1;
 }
 
-int ext4_fname_disk_to_usr(struct ext4_fname_crypto_ctx *ctx,
+int ext4_fname_disk_to_usr(struct inode *inode,
 			   struct dx_hash_info *hinfo,
 			   const struct ext4_dir_entry_2 *de,
 			   struct ext4_str *oname)
@@ -531,21 +398,20 @@ int ext4_fname_disk_to_usr(struct ext4_fname_crypto_ctx *ctx,
 	struct ext4_str iname = {.name = (unsigned char *) de->name,
 				 .len = de->name_len };
 
-	return _ext4_fname_disk_to_usr(ctx, hinfo, &iname, oname);
+	return _ext4_fname_disk_to_usr(inode, hinfo, &iname, oname);
 }
 
 
 /**
  * ext4_fname_usr_to_disk() - converts a filename from user space to disk space
  */
-int ext4_fname_usr_to_disk(struct ext4_fname_crypto_ctx *ctx,
+int ext4_fname_usr_to_disk(struct inode *inode,
 			   const struct qstr *iname,
 			   struct ext4_str *oname)
 {
 	int res;
+	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
 
-	if (ctx == NULL)
-		return -EIO;
 	if (iname->len < 3) {
 		/*Check for . and .. */
 		if (iname->name[0] == '.' &&
@@ -556,8 +422,8 @@ int ext4_fname_usr_to_disk(struct ext4_fname_crypto_ctx *ctx,
 			return oname->len;
 		}
 	}
-	if (ctx->has_valid_key) {
-		res = ext4_fname_encrypt(ctx, iname, oname);
+	if (ci) {
+		res = ext4_fname_encrypt(inode, iname, oname);
 		return res;
 	}
 	/* Without a proper key, a user is not allowed to modify the filenames
@@ -569,16 +435,13 @@ int ext4_fname_usr_to_disk(struct ext4_fname_crypto_ctx *ctx,
 int ext4_fname_setup_filename(struct inode *dir, const struct qstr *iname,
 			      int lookup, struct ext4_filename *fname)
 {
-	struct ext4_fname_crypto_ctx *ctx;
+	struct ext4_crypt_info *ci;
 	int ret = 0, bigname = 0;
 
 	memset(fname, 0, sizeof(struct ext4_filename));
 	fname->usr_fname = iname;
 
-	ctx = ext4_get_fname_crypto_ctx(dir, EXT4_NAME_LEN);
-	if (IS_ERR(ctx))
-		return PTR_ERR(ctx);
-	if ((ctx == NULL) ||
+	if (!ext4_encrypted_inode(dir) ||
 	    ((iname->name[0] == '.') &&
 	     ((iname->len == 1) ||
 	      ((iname->name[1] == '.') && (iname->len == 2))))) {
@@ -586,12 +449,16 @@ int ext4_fname_setup_filename(struct inode *dir, const struct qstr *iname,
 		fname->disk_name.len = iname->len;
 		goto out;
 	}
-	if (ctx->has_valid_key) {
-		ret = ext4_fname_crypto_alloc_buffer(ctx, iname->len,
+	ret = ext4_setup_fname_crypto(dir);
+	if (ret)
+		return ret;
+	ci = EXT4_I(dir)->i_crypt_info;
+	if (ci) {
+		ret = ext4_fname_crypto_alloc_buffer(dir, iname->len,
 						     &fname->crypto_buf);
 		if (ret < 0)
 			goto out;
-		ret = ext4_fname_encrypt(ctx, iname, &fname->crypto_buf);
+		ret = ext4_fname_encrypt(dir, iname, &fname->crypto_buf);
 		if (ret < 0)
 			goto out;
 		fname->disk_name.name = fname->crypto_buf.name;
@@ -634,7 +501,6 @@ int ext4_fname_setup_filename(struct inode *dir, const struct qstr *iname,
 	}
 	ret = 0;
 out:
-	ext4_put_fname_crypto_ctx(&ctx);
 	return ret;
 }
 

fs/ext4/crypto_key.c

@@ -84,14 +84,26 @@ out:
 	return res;
 }
 
-/**
- * ext4_generate_encryption_key() - generates an encryption key
- * @inode: The inode to generate the encryption key for.
- */
-int ext4_generate_encryption_key(struct inode *inode)
+void ext4_free_encryption_info(struct inode *inode)
+{
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	struct ext4_crypt_info *ci = ei->i_crypt_info;
+
+	if (!ci)
+		return;
+
+	if (ci->ci_keyring_key)
+		key_put(ci->ci_keyring_key);
+	crypto_free_ablkcipher(ci->ci_ctfm);
+	memzero_explicit(&ci->ci_raw, sizeof(ci->ci_raw));
+	kfree(ci);
+	ei->i_crypt_info = NULL;
+}
+
+int _ext4_get_encryption_info(struct inode *inode)
 {
 	struct ext4_inode_info *ei = EXT4_I(inode);
-	struct ext4_crypt_info *crypt_info = &ei->i_crypt_info;
+	struct ext4_crypt_info *crypt_info;
 	char full_key_descriptor[EXT4_KEY_DESC_PREFIX_SIZE +
 				 (EXT4_KEY_DESCRIPTOR_SIZE * 2) + 1];
 	struct key *keyring_key = NULL;
@@ -99,18 +111,40 @@ int ext4_generate_encryption_key(struct inode *inode)
 	struct ext4_encryption_context ctx;
 	struct user_key_payload *ukp;
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
-	int res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION,
-				 EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
-				 &ctx, sizeof(ctx));
+	int res;
 
-	if (res != sizeof(ctx)) {
-		if (res > 0)
-			res = -EINVAL;
-		goto out;
+	if (ei->i_crypt_info) {
+		if (!ei->i_crypt_info->ci_keyring_key ||
+		    key_validate(ei->i_crypt_info->ci_keyring_key) == 0)
+			return 0;
+		ext4_free_encryption_info(inode);
 	}
+
+	res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION,
+				 EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
+				 &ctx, sizeof(ctx));
+	if (res < 0) {
+		if (!DUMMY_ENCRYPTION_ENABLED(sbi))
+			return res;
+		ctx.contents_encryption_mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
+		ctx.filenames_encryption_mode =
+			EXT4_ENCRYPTION_MODE_AES_256_CTS;
+		ctx.flags = 0;
+	} else if (res != sizeof(ctx))
+		return -EINVAL;
 	res = 0;
 
+	crypt_info = kmalloc(sizeof(struct ext4_crypt_info), GFP_KERNEL);
+	if (!crypt_info)
+		return -ENOMEM;
+
 	ei->i_crypt_policy_flags = ctx.flags;
+	crypt_info->ci_flags = ctx.flags;
+	crypt_info->ci_data_mode = ctx.contents_encryption_mode;
+	crypt_info->ci_filename_mode = ctx.filenames_encryption_mode;
+	crypt_info->ci_ctfm = NULL;
+	memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor,
+	       sizeof(crypt_info->ci_master_key));
 	if (S_ISREG(inode->i_mode))
 		crypt_info->ci_mode = ctx.contents_encryption_mode;
 	else if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
@@ -151,17 +185,23 @@ int ext4_generate_encryption_key(struct inode *inode)
 	res = ext4_derive_key_aes(ctx.nonce, master_key->raw,
 				  crypt_info->ci_raw);
 out:
+	if (res < 0) {
+		if (res == -ENOKEY)
+			res = 0;
+		kfree(crypt_info);
+	} else {
+		ei->i_crypt_info = crypt_info;
+		crypt_info->ci_keyring_key = keyring_key;
+		keyring_key = NULL;
+	}
 	if (keyring_key)
 		key_put(keyring_key);
-	if (res < 0)
-		crypt_info->ci_mode = EXT4_ENCRYPTION_MODE_INVALID;
 	return res;
 }
 
 int ext4_has_encryption_key(struct inode *inode)
 {
 	struct ext4_inode_info *ei = EXT4_I(inode);
-	struct ext4_crypt_info *crypt_info = &ei->i_crypt_info;
 
-	return (crypt_info->ci_mode != EXT4_ENCRYPTION_MODE_INVALID);
+	return (ei->i_crypt_info != NULL);
 }

fs/ext4/crypto_policy.c

@@ -126,7 +126,7 @@ int ext4_get_policy(struct inode *inode, struct ext4_encryption_policy *policy)
 int ext4_is_child_context_consistent_with_parent(struct inode *parent,
 						 struct inode *child)
 {
-	struct ext4_encryption_context parent_ctx, child_ctx;
+	struct ext4_crypt_info *parent_ci, *child_ci;
 	int res;
 
 	if ((parent == NULL) || (child == NULL)) {
@@ -136,26 +136,28 @@ int ext4_is_child_context_consistent_with_parent(struct inode *parent,
 	/* no restrictions if the parent directory is not encrypted */
 	if (!ext4_encrypted_inode(parent))
 		return 1;
-	res = ext4_xattr_get(parent, EXT4_XATTR_INDEX_ENCRYPTION,
-			     EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
-			     &parent_ctx, sizeof(parent_ctx));
-	if (res != sizeof(parent_ctx))
-		return 0;
 	/* if the child directory is not encrypted, this is always a problem */
 	if (!ext4_encrypted_inode(child))
 		return 0;
-	res = ext4_xattr_get(child, EXT4_XATTR_INDEX_ENCRYPTION,
-			     EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
-			     &child_ctx, sizeof(child_ctx));
-	if (res != sizeof(child_ctx))
+	res = ext4_get_encryption_info(parent);
+	if (res)
+		return 0;
+	res = ext4_get_encryption_info(child);
+	if (res)
+		return 0;
+	parent_ci = EXT4_I(parent)->i_crypt_info;
+	child_ci = EXT4_I(child)->i_crypt_info;
+	if (!parent_ci && !child_ci)
+		return 1;
+	if (!parent_ci || !child_ci)
 		return 0;
-	return (memcmp(parent_ctx.master_key_descriptor,
-		       child_ctx.master_key_descriptor,
+
+	return (memcmp(parent_ci->ci_master_key,
+		       child_ci->ci_master_key,
 		       EXT4_KEY_DESCRIPTOR_SIZE) == 0 &&
-		(parent_ctx.contents_encryption_mode ==
-		 child_ctx.contents_encryption_mode) &&
-		(parent_ctx.filenames_encryption_mode ==
-		 child_ctx.filenames_encryption_mode));
+		(parent_ci->ci_data_mode == child_ci->ci_data_mode) &&
+		(parent_ci->ci_filename_mode == child_ci->ci_filename_mode) &&
+		(parent_ci->ci_flags == child_ci->ci_flags));
 }
 
 /**
@@ -168,31 +170,37 @@ int ext4_is_child_context_consistent_with_parent(struct inode *parent,
 int ext4_inherit_context(struct inode *parent, struct inode *child)
 {
 	struct ext4_encryption_context ctx;
-	int res = ext4_xattr_get(parent, EXT4_XATTR_INDEX_ENCRYPTION,
-				 EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
-				 &ctx, sizeof(ctx));
+	struct ext4_crypt_info *ci;
+	int res;
+
+	res = ext4_get_encryption_info(parent);
+	if (res < 0)
+		return res;
+	ci = EXT4_I(parent)->i_crypt_info;
+	BUG_ON(ci == NULL);
 
-	if (res != sizeof(ctx)) {
-		if (DUMMY_ENCRYPTION_ENABLED(EXT4_SB(parent->i_sb))) {
-			ctx.format = EXT4_ENCRYPTION_CONTEXT_FORMAT_V1;
-			ctx.contents_encryption_mode =
-				EXT4_ENCRYPTION_MODE_AES_256_XTS;
-			ctx.filenames_encryption_mode =
-				EXT4_ENCRYPTION_MODE_AES_256_CTS;
-			ctx.flags = 0;
-			memset(ctx.master_key_descriptor, 0x42,
-			       EXT4_KEY_DESCRIPTOR_SIZE);
-			res = 0;
-		} else {
-			goto out;
-		}
+	ctx.format = EXT4_ENCRYPTION_CONTEXT_FORMAT_V1;
+	if (DUMMY_ENCRYPTION_ENABLED(EXT4_SB(parent->i_sb))) {
+		ctx.contents_encryption_mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
+		ctx.filenames_encryption_mode =
+			EXT4_ENCRYPTION_MODE_AES_256_CTS;
+		ctx.flags = 0;
+		memset(ctx.master_key_descriptor, 0x42,
+		       EXT4_KEY_DESCRIPTOR_SIZE);
+		res = 0;
+	} else {
+		ctx.contents_encryption_mode = ci->ci_data_mode;
+		ctx.filenames_encryption_mode = ci->ci_filename_mode;
+		ctx.flags = ci->ci_flags;
+		memcpy(ctx.master_key_descriptor, ci->ci_master_key,
+		       EXT4_KEY_DESCRIPTOR_SIZE);
 	}
 	get_random_bytes(ctx.nonce, EXT4_KEY_DERIVATION_NONCE_SIZE);
 	res = ext4_xattr_set(child, EXT4_XATTR_INDEX_ENCRYPTION,
 			     EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
 			     sizeof(ctx), 0);
-out:
 	if (!res)
 		ext4_set_inode_flag(child, EXT4_INODE_ENCRYPT);
 	return res;
+
 }

fs/ext4/dir.c

@@ -110,7 +110,6 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
 	struct super_block *sb = inode->i_sb;
 	struct buffer_head *bh = NULL;
 	int dir_has_error = 0;
-	struct ext4_fname_crypto_ctx *enc_ctx = NULL;
 	struct ext4_str fname_crypto_str = {.name = NULL, .len = 0};
 
 	if (is_dx_dir(inode)) {
@@ -134,16 +133,14 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
 			return err;
 	}
 
-	enc_ctx = ext4_get_fname_crypto_ctx(inode, EXT4_NAME_LEN);
-	if (IS_ERR(enc_ctx))
-		return PTR_ERR(enc_ctx);
-	if (enc_ctx) {
-		err = ext4_fname_crypto_alloc_buffer(enc_ctx, EXT4_NAME_LEN,
+	err = ext4_setup_fname_crypto(inode);
+	if (err)
+		return err;
+	if (ext4_encrypted_inode(inode)) {
+		err = ext4_fname_crypto_alloc_buffer(inode, EXT4_NAME_LEN,
 						     &fname_crypto_str);
-		if (err < 0) {
-			ext4_put_fname_crypto_ctx(&enc_ctx);
+		if (err < 0)
 			return err;
-		}
 	}
 
 	offset = ctx->pos & (sb->s_blocksize - 1);
@@ -239,8 +236,7 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
 			offset += ext4_rec_len_from_disk(de->rec_len,
 					sb->s_blocksize);
 			if (le32_to_cpu(de->inode)) {
-				if (enc_ctx == NULL) {
-					/* Directory is not encrypted */
+				if (!ext4_encrypted_inode(inode)) {
 					if (!dir_emit(ctx, de->name,
 					    de->name_len,
 					    le32_to_cpu(de->inode),
@@ -250,7 +246,7 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
 					int save_len = fname_crypto_str.len;
 
 					/* Directory is encrypted */
-					err = ext4_fname_disk_to_usr(enc_ctx,
+					err = ext4_fname_disk_to_usr(inode,
 						NULL, de, &fname_crypto_str);
 					fname_crypto_str.len = save_len;
 					if (err < 0)
@@ -275,7 +271,6 @@ done:
 	err = 0;
 errout:
 #ifdef CONFIG_EXT4_FS_ENCRYPTION
-	ext4_put_fname_crypto_ctx(&enc_ctx);
 	ext4_fname_crypto_free_buffer(&fname_crypto_str);
 #endif
 	brelse(bh);

fs/ext4/ext4.h

@@ -955,7 +955,7 @@ struct ext4_inode_info {
 
 #ifdef CONFIG_EXT4_FS_ENCRYPTION
 	/* Encryption params */
-	struct ext4_crypt_info i_crypt_info;
+	struct ext4_crypt_info *i_crypt_info;
 #endif
 };
 
@@ -2096,37 +2096,30 @@ static inline int ext4_sb_has_crypto(struct super_block *sb)
 /* crypto_fname.c */
 bool ext4_valid_filenames_enc_mode(uint32_t mode);
 u32 ext4_fname_crypto_round_up(u32 size, u32 blksize);
-int ext4_fname_crypto_alloc_buffer(struct ext4_fname_crypto_ctx *ctx,
+int ext4_fname_crypto_alloc_buffer(struct inode *inode,
 				   u32 ilen, struct ext4_str *crypto_str);
-int _ext4_fname_disk_to_usr(struct ext4_fname_crypto_ctx *ctx,
+int _ext4_fname_disk_to_usr(struct inode *inode,
 			    struct dx_hash_info *hinfo,
 			    const struct ext4_str *iname,
 			    struct ext4_str *oname);
-int ext4_fname_disk_to_usr(struct ext4_fname_crypto_ctx *ctx,
+int ext4_fname_disk_to_usr(struct inode *inode,
 			   struct dx_hash_info *hinfo,
 			   const struct ext4_dir_entry_2 *de,
 			   struct ext4_str *oname);
-int ext4_fname_usr_to_disk(struct ext4_fname_crypto_ctx *ctx,
+int ext4_fname_usr_to_disk(struct inode *inode,
 			   const struct qstr *iname,
 			   struct ext4_str *oname);
-int ext4_fname_crypto_namelen_on_disk(struct ext4_fname_crypto_ctx *ctx,
-				      u32 namelen);
 #ifdef CONFIG_EXT4_FS_ENCRYPTION
-void ext4_put_fname_crypto_ctx(struct ext4_fname_crypto_ctx **ctx);
-struct ext4_fname_crypto_ctx *ext4_get_fname_crypto_ctx(struct inode *inode,
-							u32 max_len);
+int ext4_setup_fname_crypto(struct inode *inode);
 void ext4_fname_crypto_free_buffer(struct ext4_str *crypto_str);
 int ext4_fname_setup_filename(struct inode *dir, const struct qstr *iname,
 			      int lookup, struct ext4_filename *fname);
 void ext4_fname_free_filename(struct ext4_filename *fname);
 #else
 static inline
-void ext4_put_fname_crypto_ctx(struct ext4_fname_crypto_ctx **ctx) { }
-static inline
-struct ext4_fname_crypto_ctx *ext4_get_fname_crypto_ctx(struct inode *inode,
-							u32 max_len)
+int ext4_setup_fname_crypto(struct inode *inode)
 {
-	return NULL;
+	return 0;
 }
 static inline void ext4_fname_crypto_free_buffer(struct ext4_str *p) { }
 static inline int ext4_fname_setup_filename(struct inode *dir,
@@ -2143,15 +2136,34 @@ static inline void ext4_fname_free_filename(struct ext4_filename *fname) { }
 
 
 /* crypto_key.c */
-int ext4_generate_encryption_key(struct inode *inode);
+void ext4_free_encryption_info(struct inode *inode);
+int _ext4_get_encryption_info(struct inode *inode);
 
 #ifdef CONFIG_EXT4_FS_ENCRYPTION
 int ext4_has_encryption_key(struct inode *inode);
+
+static inline int ext4_get_encryption_info(struct inode *inode)
+{
+	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
+
+	if (!ci ||
+	    (ci->ci_keyring_key &&
+	     (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) |
+					   (1 << KEY_FLAG_REVOKED) |
+					   (1 << KEY_FLAG_DEAD)))))
+		return _ext4_get_encryption_info(inode);
+	return 0;
+}
+
 #else
 static inline int ext4_has_encryption_key(struct inode *inode)
 {
 	return 0;
 }
+static inline int ext4_get_encryption_info(struct inode *inode)
+{
+	return 0;
+}
 #endif
 
 

fs/ext4/ext4_crypto.h

@@ -76,7 +76,13 @@ struct ext4_encryption_key {
 struct ext4_crypt_info {
 	unsigned char	ci_mode;
 	unsigned char	ci_size;
+	char		ci_data_mode;
+	char		ci_filename_mode;
+	char		ci_flags;
+	struct crypto_ablkcipher *ci_ctfm;
+	struct key	*ci_keyring_key;
 	char		ci_raw[EXT4_MAX_KEY_SIZE];
+	char		ci_master_key[EXT4_KEY_DESCRIPTOR_SIZE];
 };
 
 #define EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL             0x00000001
@@ -128,16 +134,6 @@ struct ext4_str {
 	u32 len;
 };
 
-struct ext4_fname_crypto_ctx {
-	u32 lim;
-	struct crypto_ablkcipher *ctfm;
-	struct crypto_hash *htfm;
-	struct ext4_crypt_info ci;
-	unsigned flags : 8;
-	unsigned has_valid_key : 1;
-	unsigned ctfm_key_is_ready : 1;
-};
-
 /**
  * For encrypted symlinks, the ciphertext length is stored at the beginning
  * of the string in little-endian format.

fs/ext4/file.c

@@ -223,7 +223,7 @@ static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 	struct inode *inode = file->f_mapping->host;
 
 	if (ext4_encrypted_inode(inode)) {
-		int err = ext4_generate_encryption_key(inode);
+		int err = ext4_get_encryption_info(inode);
 		if (err)
 			return 0;
 	}
@@ -289,7 +289,7 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
 	}
 	ret = dquot_file_open(inode, filp);
 	if (!ret && ext4_encrypted_inode(inode)) {
-		ret = ext4_generate_encryption_key(inode);
+		ret = ext4_get_encryption_info(inode);
 		if (ret)
 			ret = -EACCES;
 	}

fs/ext4/namei.c

@@ -607,17 +607,14 @@ static struct stats dx_show_leaf(struct inode *dir,
 				char *name;
 				struct ext4_str fname_crypto_str
 					= {.name = NULL, .len = 0};
-				struct ext4_fname_crypto_ctx *ctx = NULL;
 				int res;
 
 				name  = de->name;
 				len = de->name_len;
-				ctx = ext4_get_fname_crypto_ctx(dir,
-								EXT4_NAME_LEN);
-				if (IS_ERR(ctx)) {
-					printk(KERN_WARNING "Error acquiring"
-					" crypto ctxt--skipping crypto\n");
-					ctx = NULL;
+				res = ext4_setup_fname_crypto(dir);
+				if (res) {
+					printk(KERN_WARNING "Error setting up"
+					       " fname crypto: %d\n", res);
 				}
 				if (ctx == NULL) {
 					/* Directory is not encrypted */
@@ -637,7 +634,6 @@ static struct stats dx_show_leaf(struct inode *dir,
 							"allocating crypto "
 							"buffer--skipping "
 							"crypto\n");
-						ext4_put_fname_crypto_ctx(&ctx);
 						ctx = NULL;
 					}
 					res = ext4_fname_disk_to_usr(ctx, NULL, de,
@@ -658,7 +654,6 @@ static struct stats dx_show_leaf(struct inode *dir,
 					printk("%*.s:(E)%x.%u ", len, name,
 					       h.hash, (unsigned) ((char *) de
 								   - base));
-					ext4_put_fname_crypto_ctx(&ctx);
 					ext4_fname_crypto_free_buffer(
 						&fname_crypto_str);
 				}
@@ -944,7 +939,6 @@ static int htree_dirblock_to_tree(struct file *dir_file,
 	struct buffer_head *bh;
 	struct ext4_dir_entry_2 *de, *top;
 	int err = 0, count = 0;
-	struct ext4_fname_crypto_ctx *ctx = NULL;
 	struct ext4_str fname_crypto_str = {.name = NULL, .len = 0}, tmp_str;
 
 	dxtrace(printk(KERN_INFO "In htree dirblock_to_tree: block %lu\n",
@@ -959,17 +953,15 @@ static int htree_dirblock_to_tree(struct file *dir_file,
 					   EXT4_DIR_REC_LEN(0));
 #ifdef CONFIG_EXT4_FS_ENCRYPTION
 	/* Check if the directory is encrypted */
-	ctx = ext4_get_fname_crypto_ctx(dir, EXT4_NAME_LEN);
-	if (IS_ERR(ctx)) {
-		err = PTR_ERR(ctx);
+	err = ext4_setup_fname_crypto(dir);
+	if (err) {
 		brelse(bh);
 		return err;
 	}
-	if (ctx != NULL) {
-		err = ext4_fname_crypto_alloc_buffer(ctx, EXT4_NAME_LEN,
+	if (ext4_encrypted_inode(dir)) {
+		err = ext4_fname_crypto_alloc_buffer(dir, EXT4_NAME_LEN,
 						     &fname_crypto_str);
 		if (err < 0) {
-			ext4_put_fname_crypto_ctx(&ctx);
 			brelse(bh);
 			return err;
 		}
@@ -990,8 +982,7 @@ static int htree_dirblock_to_tree(struct file *dir_file,
 			continue;
 		if (de->inode == 0)
 			continue;
-		if (ctx == NULL) {
-			/* Directory is not encrypted */
+		if (!ext4_encrypted_inode(dir)) {
 			tmp_str.name = de->name;
 			tmp_str.len = de->name_len;
 			err = ext4_htree_store_dirent(dir_file,
@@ -1001,7 +992,7 @@ static int htree_dirblock_to_tree(struct file *dir_file,
 			int save_len = fname_crypto_str.len;
 
 			/* Directory is encrypted */
-			err = ext4_fname_disk_to_usr(ctx, hinfo, de,
+			err = ext4_fname_disk_to_usr(dir, hinfo, de,
 						     &fname_crypto_str);
 			if (err < 0) {
 				count = err;
@@ -1021,7 +1012,6 @@ static int htree_dirblock_to_tree(struct file *dir_file,
 errout:
 	brelse(bh);
 #ifdef CONFIG_EXT4_FS_ENCRYPTION
-	ext4_put_fname_crypto_ctx(&ctx);
 	ext4_fname_crypto_free_buffer(&fname_crypto_str);
 #endif
 	return count;
@@ -3107,7 +3097,6 @@ static int ext4_symlink(struct inode *dir,
 	}
 
 	if (encryption_required) {
-		struct ext4_fname_crypto_ctx *ctx = NULL;
 		struct qstr istr;
 		struct ext4_str ostr;
 
@@ -3119,19 +3108,14 @@ static int ext4_symlink(struct inode *dir,
 		err = ext4_inherit_context(dir, inode);
 		if (err)
 			goto err_drop_inode;
-		ctx = ext4_get_fname_crypto_ctx(inode,
-						inode->i_sb->s_blocksize);
-		if (IS_ERR_OR_NULL(ctx)) {
-			/* We just set the policy, so ctx should not be NULL */
-			err = (ctx == NULL) ? -EIO : PTR_ERR(ctx);
+		err = ext4_setup_fname_crypto(inode);
+		if (err)
 			goto err_drop_inode;
-		}
 		istr.name = (const unsigned char *) symname;
 		istr.len = len;
 		ostr.name = sd->encrypted_path;
 		ostr.len = disk_link.len;
-		err = ext4_fname_usr_to_disk(ctx, &istr, &ostr);
-		ext4_put_fname_crypto_ctx(&ctx);
+		err = ext4_fname_usr_to_disk(inode, &istr, &ostr);
 		if (err < 0)
 			goto err_drop_inode;
 		sd->len = cpu_to_le16(ostr.len);

fs/ext4/super.c

@@ -879,9 +879,8 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
 	atomic_set(&ei->i_unwritten, 0);
 	INIT_WORK(&ei->i_rsv_conversion_work, ext4_end_io_rsv_work);
 #ifdef CONFIG_EXT4_FS_ENCRYPTION
-	ei->i_crypt_info.ci_mode = EXT4_ENCRYPTION_MODE_INVALID;
+	ei->i_crypt_info = NULL;
 #endif
-
 	return &ei->vfs_inode;
 }
 
@@ -958,6 +957,10 @@ void ext4_clear_inode(struct inode *inode)
 		jbd2_free_inode(EXT4_I(inode)->jinode);
 		EXT4_I(inode)->jinode = NULL;
 	}
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+	if (EXT4_I(inode)->i_crypt_info)
+		ext4_free_encryption_info(inode);
+#endif
 }
 
 static struct inode *ext4_nfs_get_inode(struct super_block *sb,

fs/ext4/symlink.c

@@ -29,7 +29,6 @@ static void *ext4_follow_link(struct dentry *dentry, struct nameidata *nd)
 	char *caddr, *paddr = NULL;
 	struct ext4_str cstr, pstr;
 	struct inode *inode = d_inode(dentry);
-	struct ext4_fname_crypto_ctx *ctx = NULL;
 	struct ext4_encrypted_symlink_data *sd;
 	loff_t size = min_t(loff_t, i_size_read(inode), PAGE_SIZE - 1);
 	int res;
@@ -38,19 +37,17 @@ static void *ext4_follow_link(struct dentry *dentry, struct nameidata *nd)
 	if (!ext4_encrypted_inode(inode))
 		return page_follow_link_light(dentry, nd);
 
-	ctx = ext4_get_fname_crypto_ctx(inode, inode->i_sb->s_blocksize);
-	if (IS_ERR(ctx))
-		return ctx;
+	res = ext4_setup_fname_crypto(inode);
+	if (res)
+		return ERR_PTR(res);
 
 	if (ext4_inode_is_fast_symlink(inode)) {
 		caddr = (char *) EXT4_I(inode)->i_data;
 		max_size = sizeof(EXT4_I(inode)->i_data);
 	} else {
 		cpage = read_mapping_page(inode->i_mapping, 0, NULL);
-		if (IS_ERR(cpage)) {
-			ext4_put_fname_crypto_ctx(&ctx);
+		if (IS_ERR(cpage))
 			return cpage;
-		}
 		caddr = kmap(cpage);
 		caddr[size] = 0;
 	}
@@ -75,21 +72,19 @@ static void *ext4_follow_link(struct dentry *dentry, struct nameidata *nd)
 	}
 	pstr.name = paddr;
 	pstr.len = plen;
-	res = _ext4_fname_disk_to_usr(ctx, NULL, &cstr, &pstr);
+	res = _ext4_fname_disk_to_usr(inode, NULL, &cstr, &pstr);
 	if (res < 0)
 		goto errout;
 	/* Null-terminate the name */
 	if (res <= plen)
 		paddr[res] = '\0';
 	nd_set_link(nd, paddr);
-	ext4_put_fname_crypto_ctx(&ctx);
 	if (cpage) {
 		kunmap(cpage);
 		page_cache_release(cpage);
 	}
 	return NULL;
 errout:
-	ext4_put_fname_crypto_ctx(&ctx);
 	if (cpage) {
 		kunmap(cpage);
 		page_cache_release(cpage);