crypto: nx - Fix timing leak in GCM and CCM decryption

Using non-constant time memcmp() makes the verification of the authentication
tag in the decrypt path vulnerable to timing attacks. Fix this by using
crypto_memneq() instead.

Cc: stable@vger.kernel.org
Signed-off-by: David Gstir <david@sigma-star.at>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
David Gstir 2015-11-15 17:14:41 +01:00 committed by Herbert Xu
parent 8005c49d9a
commit cb8affb55c
2 changed files with 3 additions and 2 deletions

View File

@ -409,7 +409,7 @@ static int ccm_nx_decrypt(struct aead_request *req,
processed += to_process;
} while (processed < nbytes);
rc = memcmp(csbcpb->cpb.aes_ccm.out_pat_or_mac, priv->oauth_tag,
rc = crypto_memneq(csbcpb->cpb.aes_ccm.out_pat_or_mac, priv->oauth_tag,
authsize) ? -EBADMSG : 0;
out:
spin_unlock_irqrestore(&nx_ctx->lock, irq_flags);

View File

@ -21,6 +21,7 @@
#include <crypto/internal/aead.h>
#include <crypto/aes.h>
#include <crypto/algapi.h>
#include <crypto/scatterwalk.h>
#include <linux/module.h>
#include <linux/types.h>
@ -418,7 +419,7 @@ mac:
itag, req->src, req->assoclen + nbytes,
crypto_aead_authsize(crypto_aead_reqtfm(req)),
SCATTERWALK_FROM_SG);
rc = memcmp(itag, otag,
rc = crypto_memneq(itag, otag,
crypto_aead_authsize(crypto_aead_reqtfm(req))) ?
-EBADMSG : 0;
}