crypto: hash - Fixed digest size check

The digest size check on hash algorithms is incorrect. It's perfectly valid for hash algorithms to have a digest length longer than their block size. For example crc32c has a block size of 1 and a digest size of 4. Rather than having it lie about its block size, this patch fixes the checks to do what they really should which is to bound the digest size so that code placing the digest on the stack continue to work. HMAC however still needs to check this as it's only defined for such algorithms. Signed-off-by: Herbert Xu <[email protected]>
ambv · Jul 10, 2008 · ca786dc · ca786dc
1 parent caee168
commit ca786dc
Show file tree

Hide file tree

Showing 4 changed files with 13 additions and 9 deletions.
diff --git a/crypto/ahash.c b/crypto/ahash.c
@@ -68,7 +68,7 @@ static int crypto_init_ahash_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
 	struct ahash_alg *alg = &tfm->__crt_alg->cra_ahash;
 	struct ahash_tfm *crt   = &tfm->crt_ahash;
 
-	if (alg->digestsize > crypto_tfm_alg_blocksize(tfm))
+	if (alg->digestsize > PAGE_SIZE / 8)
 		return -EINVAL;
 
 	crt->init = alg->init;

diff --git a/crypto/digest.c b/crypto/digest.c
@@ -141,7 +141,7 @@ int crypto_init_digest_ops(struct crypto_tfm *tfm)
 	struct hash_tfm *ops = &tfm->crt_hash;
 	struct digest_alg *dalg = &tfm->__crt_alg->cra_digest;
 
-	if (dalg->dia_digestsize > crypto_tfm_alg_blocksize(tfm))
+	if (dalg->dia_digestsize > PAGE_SIZE / 8)
 		return -EINVAL;
 
 	ops->init	= init;

diff --git a/crypto/hash.c b/crypto/hash.c
@@ -152,7 +152,7 @@ static int crypto_init_hash_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
 {
 	struct hash_alg *alg = &tfm->__crt_alg->cra_hash;
 
-	if (alg->digestsize > crypto_tfm_alg_blocksize(tfm))
+	if (alg->digestsize > PAGE_SIZE / 8)
 		return -EINVAL;
 
 	if ((mask & CRYPTO_ALG_TYPE_HASH_MASK) != CRYPTO_ALG_TYPE_HASH_MASK)

diff --git a/crypto/hmac.c b/crypto/hmac.c
@@ -226,6 +226,7 @@ static struct crypto_instance *hmac_alloc(struct rtattr **tb)
 	struct crypto_instance *inst;
 	struct crypto_alg *alg;
 	int err;
+	int ds;
 
 	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_HASH);
 	if (err)
@@ -236,6 +237,13 @@ static struct crypto_instance *hmac_alloc(struct rtattr **tb)
 	if (IS_ERR(alg))
 		return ERR_CAST(alg);
 
+	inst = ERR_PTR(-EINVAL);
+	ds = (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
+	     CRYPTO_ALG_TYPE_HASH ? alg->cra_hash.digestsize :
+				    alg->cra_digest.dia_digestsize;
+	if (ds > alg->cra_blocksize)
+		goto out_put_alg;
+
 	inst = crypto_alloc_instance("hmac", alg);
 	if (IS_ERR(inst))
 		goto out_put_alg;
@@ -246,14 +254,10 @@ static struct crypto_instance *hmac_alloc(struct rtattr **tb)
 	inst->alg.cra_alignmask = alg->cra_alignmask;
 	inst->alg.cra_type = &crypto_hash_type;
 
-	inst->alg.cra_hash.digestsize =
-		(alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
-		CRYPTO_ALG_TYPE_HASH ? alg->cra_hash.digestsize :
-				       alg->cra_digest.dia_digestsize;
+	inst->alg.cra_hash.digestsize = ds;
 
 	inst->alg.cra_ctxsize = sizeof(struct hmac_ctx) +
-				ALIGN(inst->alg.cra_blocksize * 2 +
-				      inst->alg.cra_hash.digestsize,
+				ALIGN(inst->alg.cra_blocksize * 2 + ds,
 				      sizeof(void *));
 
 	inst->alg.cra_init = hmac_init_tfm;