Commit cb8affb5 authored by David Gstir's avatar David Gstir Committed by Herbert Xu

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: default avatarDavid Gstir <david@sigma-star.at>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 8005c49d
...@@ -409,7 +409,7 @@ static int ccm_nx_decrypt(struct aead_request *req, ...@@ -409,7 +409,7 @@ static int ccm_nx_decrypt(struct aead_request *req,
processed += to_process; processed += to_process;
} while (processed < nbytes); } 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; authsize) ? -EBADMSG : 0;
out: out:
spin_unlock_irqrestore(&nx_ctx->lock, irq_flags); spin_unlock_irqrestore(&nx_ctx->lock, irq_flags);
......
...@@ -21,6 +21,7 @@ ...@@ -21,6 +21,7 @@
#include <crypto/internal/aead.h> #include <crypto/internal/aead.h>
#include <crypto/aes.h> #include <crypto/aes.h>
#include <crypto/algapi.h>
#include <crypto/scatterwalk.h> #include <crypto/scatterwalk.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/types.h> #include <linux/types.h>
...@@ -418,7 +419,7 @@ static int gcm_aes_nx_crypt(struct aead_request *req, int enc, ...@@ -418,7 +419,7 @@ static int gcm_aes_nx_crypt(struct aead_request *req, int enc,
itag, req->src, req->assoclen + nbytes, itag, req->src, req->assoclen + nbytes,
crypto_aead_authsize(crypto_aead_reqtfm(req)), crypto_aead_authsize(crypto_aead_reqtfm(req)),
SCATTERWALK_FROM_SG); SCATTERWALK_FROM_SG);
rc = memcmp(itag, otag, rc = crypto_memneq(itag, otag,
crypto_aead_authsize(crypto_aead_reqtfm(req))) ? crypto_aead_authsize(crypto_aead_reqtfm(req))) ?
-EBADMSG : 0; -EBADMSG : 0;
} }
......
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