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| author | Eric Biggers <ebiggers@google.com> | 2017-12-08 16:13:29 +0100 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2017-12-08 16:13:29 +0100 |
| commit | 72f9a07b6bfaefdc29fcb75dafa8867a4f6d8317 (patch) | |
| tree | 07ca4c806753963651a86081f8dfbbce26e90c19 /crypto/asymmetric_keys | |
| parent | pkcs7: use crypto_shash_digest() (diff) | |
| download | linux-72f9a07b6bfaefdc29fcb75dafa8867a4f6d8317.tar.xz linux-72f9a07b6bfaefdc29fcb75dafa8867a4f6d8317.zip | |
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/asymmetric_keys')
| -rw-r--r-- | crypto/asymmetric_keys/public_key.c | 7 |
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); |