144 lines
3.3 KiB
Diff
144 lines
3.3 KiB
Diff
From ff5e59f32255913bb1cdf51441b98c9107ae165b Mon Sep 17 00:00:00 2001
|
||
From: Benjamin Tissoires <benjamin.tissoires@gmail.com>
|
||
Date: Tue, 4 Apr 2017 19:12:53 +0200
|
||
Subject: Use getentropy() if arc4random_buf() is not available
|
||
|
||
This allows to fix CVE-2017-2626 on Linux platforms without pulling in
|
||
libbsd.
|
||
The libc getentropy() is available since glibc 2.25 but also on OpenBSD.
|
||
For Linux, we need at least a v3.17 kernel. If the recommended
|
||
arc4random_buf() function is not available, emulate it by first trying
|
||
to use getentropy() on a supported glibc and kernel. If the call fails,
|
||
fall back to the current (partly vulnerable) code.
|
||
|
||
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
|
||
Reviewed-by: Mark Kettenis <kettenis@openbsd.org>
|
||
Reviewed-by: Alan Coopersmith <alan.coopersmith@oracle.com>
|
||
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
|
||
---
|
||
configure.ac | 2 +-
|
||
src/iceauth.c | 65 ++++++++++++++++++++++++++++++++++++++++++-----------------
|
||
2 files changed, 47 insertions(+), 20 deletions(-)
|
||
|
||
diff --git a/configure.ac b/configure.ac
|
||
index 458882a..c971ab6 100644
|
||
--- a/configure.ac
|
||
+++ b/configure.ac
|
||
@@ -38,7 +38,7 @@ AC_DEFINE(ICE_t, 1, [Xtrans transport type])
|
||
|
||
# Checks for library functions.
|
||
AC_CHECK_LIB([bsd], [arc4random_buf])
|
||
-AC_CHECK_FUNCS([asprintf arc4random_buf])
|
||
+AC_CHECK_FUNCS([asprintf arc4random_buf getentropy])
|
||
|
||
# Allow checking code with lint, sparse, etc.
|
||
XORG_WITH_LINT
|
||
diff --git a/src/iceauth.c b/src/iceauth.c
|
||
index ed31683..de4785b 100644
|
||
--- a/src/iceauth.c
|
||
+++ b/src/iceauth.c
|
||
@@ -44,31 +44,19 @@ Author: Ralph Mor, X Consortium
|
||
|
||
static int was_called_state;
|
||
|
||
-/*
|
||
- * MIT-MAGIC-COOKIE-1 is a sample authentication method implemented by
|
||
- * the SI. It is not part of standard ICElib.
|
||
- */
|
||
+#ifndef HAVE_ARC4RANDOM_BUF
|
||
|
||
-
|
||
-char *
|
||
-IceGenerateMagicCookie (
|
||
+static void
|
||
+emulate_getrandom_buf (
|
||
+ char *auth,
|
||
int len
|
||
)
|
||
{
|
||
- char *auth;
|
||
-#ifndef HAVE_ARC4RANDOM_BUF
|
||
long ldata[2];
|
||
int seed;
|
||
int value;
|
||
int i;
|
||
-#endif
|
||
|
||
- if ((auth = malloc (len + 1)) == NULL)
|
||
- return (NULL);
|
||
-
|
||
-#ifdef HAVE_ARC4RANDOM_BUF
|
||
- arc4random_buf(auth, len);
|
||
-#else
|
||
#ifdef ITIMER_REAL
|
||
{
|
||
struct timeval now;
|
||
@@ -76,13 +64,13 @@ IceGenerateMagicCookie (
|
||
ldata[0] = now.tv_sec;
|
||
ldata[1] = now.tv_usec;
|
||
}
|
||
-#else
|
||
+#else /* ITIMER_REAL */
|
||
{
|
||
long time ();
|
||
ldata[0] = time ((long *) 0);
|
||
ldata[1] = getpid ();
|
||
}
|
||
-#endif
|
||
+#endif /* ITIMER_REAL */
|
||
seed = (ldata[0]) + (ldata[1] << 16);
|
||
srand (seed);
|
||
for (i = 0; i < len; i++)
|
||
@@ -90,7 +78,46 @@ IceGenerateMagicCookie (
|
||
value = rand ();
|
||
auth[i] = value & 0xff;
|
||
}
|
||
-#endif
|
||
+}
|
||
+
|
||
+static void
|
||
+arc4random_buf (
|
||
+ char *auth,
|
||
+ int len
|
||
+)
|
||
+{
|
||
+ int ret;
|
||
+
|
||
+#if HAVE_GETENTROPY
|
||
+ /* weak emulation of arc4random through the entropy libc */
|
||
+ ret = getentropy (auth, len);
|
||
+ if (ret == 0)
|
||
+ return;
|
||
+#endif /* HAVE_GETENTROPY */
|
||
+
|
||
+ emulate_getrandom_buf (auth, len);
|
||
+}
|
||
+
|
||
+#endif /* !defined(HAVE_ARC4RANDOM_BUF) */
|
||
+
|
||
+/*
|
||
+ * MIT-MAGIC-COOKIE-1 is a sample authentication method implemented by
|
||
+ * the SI. It is not part of standard ICElib.
|
||
+ */
|
||
+
|
||
+
|
||
+char *
|
||
+IceGenerateMagicCookie (
|
||
+ int len
|
||
+)
|
||
+{
|
||
+ char *auth;
|
||
+
|
||
+ if ((auth = malloc (len + 1)) == NULL)
|
||
+ return (NULL);
|
||
+
|
||
+ arc4random_buf (auth, len);
|
||
+
|
||
auth[len] = '\0';
|
||
return (auth);
|
||
}
|
||
--
|
||
cgit v1.1
|
||
|
||
|