- djm@cvs.openbsd.org 2010/07/13 11:52:06

     [auth-rsa.c channels.c jpake.c key.c misc.c misc.h monitor.c]
     [packet.c ssh-rsa.c]
     implement a timing_safe_cmp() function to compare memory without leaking
     timing information by short-circuiting like memcmp() and use it for
     some of the more sensitive comparisons (though nothing high-value was
     readily attackable anyway); "looks ok" markus@

1 files changed, 13 insertions, 1 deletions

diff --git a/misc.c b/misc.c
index 4500b7a37..3b98e3fc2 100644
--- a/misc.c
+++ b/misc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: misc.c,v 1.77 2010/07/02 04:32:44 djm Exp $ */
+/* $OpenBSD: misc.c,v 1.78 2010/07/13 11:52:06 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2005,2006 Damien Miller.  All rights reserved.
@@ -850,6 +850,18 @@ ms_to_timeval(struct timeval *tv, int ms)
         tv->tv_usec = (ms % 1000) * 1000;
 }
 
+int
+timing_safe_cmp(const void *_s1, const void *_s2, size_t n)
+{
+        u_char *s1 = (u_char *)_s1;
+        u_char *s2 = (u_char *)_s2;
+        int ret = 0;
+
+        for (; n > 0; n--, s1++, s2++)
+                ret |= *s1 ^ *s2;
+        return ret;
+}
+
 void
 sock_set_v6only(int s)
 {