Commit 26bc83b8 authored by Eric Biggers's avatar Eric Biggers Committed by Steve French
Browse files

smb: client: Compare MACs in constant time 



To prevent timing attacks, MAC comparisons need to be constant-time.
Replace the memcmp() with the correct function, crypto_memneq().

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Acked-by: default avatarPaulo Alcantara (Red Hat) <pc@manguebit.org>
Signed-off-by: default avatarEric Biggers <ebiggers@kernel.org>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 8098179d

fs/smb/client/smb1encrypt.c

+2 −1
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 


#include <linux/fips.h>

#include <crypto/md5.h>

#include <crypto/utils.h>

#include "cifsproto.h"

#include "smb1proto.h"

#include "cifs_debug.h"
@@ -131,7 +132,7 @@ int cifs_verify_signature(struct smb_rqst *rqst, 
/*	cifs_dump_mem("what we think it should be: ",

		      what_we_think_sig_should_be, 16); */



	if (memcmp(server_response_sig, what_we_think_sig_should_be, 8))

	if (crypto_memneq(server_response_sig, what_we_think_sig_should_be, 8))

		return -EACCES;

	else

		return 0;

fs/smb/client/smb2transport.c

+3 −1
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/highmem.h>

#include <crypto/aead.h>

#include <crypto/sha2.h>

#include <crypto/utils.h>

#include "cifsglob.h"

#include "cifsproto.h"

#include "smb2proto.h"
@@ -617,7 +618,8 @@ smb2_verify_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server) 
	if (rc)

		return rc;



	if (memcmp(server_response_sig, shdr->Signature, SMB2_SIGNATURE_SIZE)) {

	if (crypto_memneq(server_response_sig, shdr->Signature,

			  SMB2_SIGNATURE_SIZE)) {

		cifs_dbg(VFS, "sign fail cmd 0x%x message id 0x%llx\n",

			shdr->Command, shdr->MessageId);

		return -EACCES;