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authorEric Biggers <ebiggers@google.com>2017-12-08 15:13:29 +0000
committerDavid Howells <dhowells@redhat.com>2017-12-08 15:13:29 +0000
commit72f9a07b6bfaefdc29fcb75dafa8867a4f6d8317 (patch)
tree07ca4c806753963651a86081f8dfbbce26e90c19 /crypto
parenta80745a6de51a651977a16ef81cba0126f9dd66f (diff)
downloadlinux-stericsson-72f9a07b6bfaefdc29fcb75dafa8867a4f6d8317.tar.gz
KEYS: be careful with error codes in public_key_verify_signature()
In public_key_verify_signature(), if akcipher_request_alloc() fails, we return -ENOMEM. But that error code was set 25 lines above, and by accident someone could easily insert new code in between that assigns to 'ret', which would introduce a signature verification bypass. Make the code clearer by moving the -ENOMEM down to where it is used. Additionally, the callers of public_key_verify_signature() only consider a negative return value to be an error. This means that if any positive return value is accidentally introduced deeper in the call stack (e.g. 'return EBADMSG' instead of 'return -EBADMSG' somewhere in RSA), signature verification will be bypassed. Make things more robust by having public_key_verify_signature() warn about positive errors and translate them into -EINVAL. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'crypto')
-rw-r--r--crypto/asymmetric_keys/public_key.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index bc3035ef27a2..de996586762a 100644
--- a/crypto/asymmetric_keys/public_key.c
+++ b/crypto/asymmetric_keys/public_key.c
@@ -73,7 +73,7 @@ int public_key_verify_signature(const struct public_key *pkey,
char alg_name_buf[CRYPTO_MAX_ALG_NAME];
void *output;
unsigned int outlen;
- int ret = -ENOMEM;
+ int ret;
pr_devel("==>%s()\n", __func__);
@@ -99,6 +99,7 @@ int public_key_verify_signature(const struct public_key *pkey,
if (IS_ERR(tfm))
return PTR_ERR(tfm);
+ ret = -ENOMEM;
req = akcipher_request_alloc(tfm, GFP_KERNEL);
if (!req)
goto error_free_tfm;
@@ -127,7 +128,7 @@ int public_key_verify_signature(const struct public_key *pkey,
* signature and returns that to us.
*/
ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait);
- if (ret < 0)
+ if (ret)
goto out_free_output;
/* Do the actual verification step. */
@@ -142,6 +143,8 @@ error_free_req:
error_free_tfm:
crypto_free_akcipher(tfm);
pr_devel("<==%s() = %d\n", __func__, ret);
+ if (WARN_ON_ONCE(ret > 0))
+ ret = -EINVAL;
return ret;
}
EXPORT_SYMBOL_GPL(public_key_verify_signature);