Commit dd91c79e authored by Eric Biggers's avatar Eric Biggers Committed by Jakub Kicinski
Browse files

sctp: Fix MAC comparison to be constant-time 



To prevent timing attacks, MACs need to be compared in constant time.
Use the appropriate helper function for this.

Fixes: bbd0d598 ("[SCTP]: Implement the receive and verification of AUTH chunk")
Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarEric Biggers <ebiggers@kernel.org>
Link: https://patch.msgid.link/20250818205426.30222-3-ebiggers@kernel.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 490a9591

net/sctp/sm_make_chunk.c

+2 −1
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt



#include <crypto/hash.h>

#include <crypto/utils.h>

#include <linux/types.h>

#include <linux/kernel.h>

#include <linux/ip.h>
@@ -1788,7 +1789,7 @@ struct sctp_association *sctp_unpack_cookie( 
		}

	}



	if (memcmp(digest, cookie->signature, SCTP_SIGNATURE_SIZE)) {

	if (crypto_memneq(digest, cookie->signature, SCTP_SIGNATURE_SIZE)) {

		*error = -SCTP_IERROR_BAD_SIG;

		goto fail;

	}

net/sctp/sm_statefuns.c

+2 −1
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt



#include <crypto/utils.h>

#include <linux/types.h>

#include <linux/kernel.h>

#include <linux/ip.h>
@@ -4416,7 +4417,7 @@ static enum sctp_ierror sctp_sf_authenticate( 
				 sh_key, GFP_ATOMIC);



	/* Discard the packet if the digests do not match */

	if (memcmp(save_digest, digest, sig_len)) {

	if (crypto_memneq(save_digest, digest, sig_len)) {

		kfree(save_digest);

		return SCTP_IERROR_BAD_SIG;

	}