lkml.org 
[lkml]   [2016]   [Apr]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3.12 76/78] EVM: Use crypto_memneq() for digest comparisons
Date
From: Ryan Ware <ware@linux.intel.com>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

commit 613317bd212c585c20796c10afe5daaa95d4b0a1 upstream.

This patch fixes vulnerability CVE-2016-2085. The problem exists
because the vm_verify_hmac() function includes a use of memcmp().
Unfortunately, this allows timing side channel attacks; specifically
a MAC forgery complexity drop from 2^128 to 2^12. This patch changes
the memcmp() to the cryptographically safe crypto_memneq().

Reported-by: Xiaofei Rex Guo <xiaofei.rex.guo@intel.com>
Signed-off-by: Ryan Ware <ware@linux.intel.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
security/integrity/evm/evm_main.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index d43b62c4a8e5..5bf01c8648a8 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -21,6 +21,7 @@
#include <linux/integrity.h>
#include <linux/evm.h>
#include <crypto/hash.h>
+#include <crypto/algapi.h>
#include "evm.h"

int evm_initialized;
@@ -132,7 +133,7 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
xattr_value_len, calc.digest);
if (rc)
break;
- rc = memcmp(xattr_data->digest, calc.digest,
+ rc = crypto_memneq(xattr_data->digest, calc.digest,
sizeof(calc.digest));
if (rc)
rc = -EINVAL;
--
2.8.1
\
 
 \ /
  Last update: 2016-04-22 13:21    [W:0.207 / U:0.120 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site