-------------------------------------------------------------------

Mon Jul 17 13:43:13 UTC 2017 - sndirsch@suse.com

- u_Use-better-fallbacks-to-generate-cookies-if-arc4rand.patch 

  If arc4random_buf() is not available for generating cookies:

  * use getentropy(), if available (which was only recently added to

    glibc)

  * use getrandom() via syscall(), if available (there was no glibc

    wrapper for this syscall for a long time)

  * if all else fails, directly read from /dev/urandom as before, but

    employ O_CLOEXEC, do an OsAbort() in case the random data couldn't be

    read to avoid unsecure situations. Don't know if that's too hard a

    measure but it shouldn't actually occur except on maximum number of

    FDs reached

  (bsc#1025084)

Patch1004:      u_Use-better-fallbacks-to-generate-cookies-if-arc4rand.patch

%patch1004 -p1

From 44a643812ce3c07cd38972abfa9dbd163529c192 Mon Sep 17 00:00:00 2001

From: Matthias Gerstner <mgerstner@suse.de>

Date: Thu, 13 Jul 2017 14:58:04 +0200

Subject: [PATCH] Use better fallbacks to generate cookies if arc4random_buf(3)

 is unavailable

References: bsc#1025084

If arc4random_buf() is not available for generating cookies:

- use getentropy(), if available (which was only recently added to

  glibc)

- use getrandom() via syscall(), if available (there was no glibc

  wrapper for this syscall for a long time)

- if all else fails, directly read from /dev/urandom as before, but

  employ O_CLOEXEC, do an OsAbort() in case the random data couldn't be

  read to avoid unsecure situations. Don't know if that's too hard a

  measure but it shouldn't actually occur except on maximum number of

  FDs reached

Reviewed-by: Stefan Dirsch <sndirsch@suse.de>

---

 configure.ac            |   4 +-

 include/dix-config.h.in |   6 +++

 os/auth.c               | 138 ++++++++++++++++++++++++++++++++++++++++++++++--

 3 files changed, 141 insertions(+), 7 deletions(-)

Index: xorg-server-1.6.5/configure.ac

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

--- xorg-server-1.6.5.orig/configure.ac

+++ xorg-server-1.6.5/configure.ac

@@ -101,7 +101,7 @@ AM_CONDITIONAL(XSERVER_DTRACE, [test "x$

 AC_HEADER_DIRENT

 AC_HEADER_STDC

-AC_CHECK_HEADERS([fcntl.h stdlib.h string.h unistd.h])

+AC_CHECK_HEADERS([fcntl.h stdlib.h string.h unistd.h sys/syscall.h])

 dnl Checks for typedefs, structures, and compiler characteristics.

 AC_C_CONST

@@ -186,7 +186,7 @@ AC_CHECK_FUNCS([geteuid getuid link memm

 		getisax getzoneid shmctl64 strcasestr ffs])

 AC_REPLACE_FUNCS([timingsafe_memcmp])

 AC_CHECK_LIB([bsd], [arc4random_buf])

-AC_CHECK_FUNCS([arc4random_buf])

+AC_CHECK_FUNCS([arc4random_buf getentropy])

 AC_FUNC_ALLOCA

 dnl Old HAS_* names used in os/*.c.

 AC_CHECK_FUNC([getdtablesize],

Index: xorg-server-1.6.5/include/dix-config.h.in

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

--- xorg-server-1.6.5.orig/include/dix-config.h.in

+++ xorg-server-1.6.5/include/dix-config.h.in

@@ -160,6 +160,9 @@

 /* Define to 1 if you have the `arc4random_buf' function. */

 #undef HAVE_ARC4RANDOM_BUF

+/* Define to 1 if you have the `getentropy' function. */

+#undef HAVE_GETENTROPY

+

 /* Define to use libmd SHA1 functions instead of OpenSSL libcrypto */

 #undef HAVE_SHA1_IN_LIBMD

@@ -213,6 +216,9 @@

 /* Define to 1 if you have the <sys/vm86.h> header file. */

 #undef HAVE_SYS_VM86_H

+/* Define to 1 if you have the <sys/syscall.h> header file. */

+#undef HAVE_SYS_SYSCALL_H

+

 /* Define to 1 if you have the `timingsafe_memcmp' function. */

 #undef HAVE_TIMINGSAFE_MEMCMP

Index: xorg-server-1.6.5/os/auth.c

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

--- xorg-server-1.6.5.orig/os/auth.c

+++ xorg-server-1.6.5/os/auth.c

@@ -48,6 +48,10 @@ from The Open Group.

 #ifdef HAVE_LIBBSD

 #include   <bsd/stdlib.h>       /* for arc4random_buf() */

 #endif

+#include   <errno.h>

+#ifdef HAVE_SYS_SYSCALL_H

+#include   <syscall.h>

+#endif

 struct protocol {

     unsigned short   name_length;

@@ -316,18 +320,141 @@ GenerateAuthorization(

     return -1;

 }

+#if ! defined(HAVE_ARC4RANDOM_BUF)

+

+// fallback function to get random data directly from /dev/urandom

+

+static int

+GetUrandom ( char *buffer, size_t length )

+{

+    int random_fd = -1;

+    int res = -1;

+    size_t filled = 0;

+

+    // larger requests are typically rejected by getentropy() / getrandom()

+    // because they could block or return partially filled buffers

+    if( length > 256 ) {

+        errno = EIO;

+        return -1;

+    }

+

+    random_fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC);

+

+    if( random_fd == -1 ) {

+        return -1;

+    }

+

+    while( filled < length ) {

+        res = read(random_fd, (char*)buffer + filled, length - filled);

+

+        if( res == -1 ) {

+            // shouldn't actually happen acc. to man(4) random,

+            // but you never know

+            if( errno == EINTR ) {

+                continue;

+            }

+

+            res = errno;

+            close(random_fd);

+            errno = res;

+            return -1;

+        }

+        else if( res == 0 ) {

+            close(random_fd);

+            // no more bytes available? should not happen

+            errno = EIO;

+            return -1;

+        }

+

+        filled += res;

+    }

+

+    close(random_fd);

+

+    return 0;

+}

+

+#endif // ! defined(HAVE_ARC4RANDOM_BUF)

+

+#if !defined(HAVE_GETENTROPY) && defined(HAVE_SYS_SYSCALL_H) && defined(SYS_getrandom)

+#    define TRY_GETRANDOM

+#endif

+

+#ifdef TRY_GETRANDOM

+

+/*

+ * wrapper for the getrandom() syscall which was for a long time implemented

+ * in the Linux kernel, but not wrapped in glibc

+ */

+static int

+GetRandom ( char *buffer, size_t length )

+{

+    int res;

+    size_t filled = 0;

+

+    // larger requests are typically rejected by getentropy() / getrandom()

+    // because they could block or return partially filled buffers

+    if( length > 256 )

+    {

+        errno = EIO;

+        return -1;

+    }

+

+    while( filled < length )

+    {

+        /*

+         * glibc does not contain a syscall wrapper for this in older

+         * versions

+         */

+        res = syscall(SYS_getrandom, (char*)buffer + filled, length - filled, 0);

+

+        if( res == -1 )

+        {

+            if( errno == EINTR ) {

+                continue;

+            }

+

+            return -1;

+        }

+        else if( res == 0 )

+        {

+            // no more bytes available? should not happen

+            errno = EIO;

+            return -1;

+        }

+

+        filled += res;

+    }

+

+    return 0;

+}

+

+#endif /* TRY_GETRANDOM */

+

 void

 GenerateRandomData (int len, char *buf)

 {

 #ifdef HAVE_ARC4RANDOM_BUF

     arc4random_buf(buf, len);

 #else

-    int fd;

-

-    fd = open("/dev/urandom", O_RDONLY);

-    read(fd, buf, len);

-    close(fd);

+    int ret = -1;

+#ifdef HAVE_GETENTROPY

+    /* use getentropy instead */

+    ret = getentropy (buf, len);

+#elif defined(TRY_GETRANDOM)

+    /* try getrandom() wrapper */

+    ret = GetRandom(buf, len);

 #endif

+

+    if( ret == -1 ) {

+	// fallback to manual reading of /dev/urandom

+	ret = GetUrandom(buf, len);

+    }

+    if( ret == -1 ) {

+	// no error return possible, rather abort than have security problems

+	OsAbort();

+    }

+#endif // HAVE_ARC4RANDOM_BUF

 }

 #endif /* XCSECURITY */

Index: xorg-server-1.6.5/include/os.h

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

--- xorg-server-1.6.5.orig/include/os.h

+++ xorg-server-1.6.5/include/os.h

@@ -264,6 +264,9 @@ void OsBlockSignals (void);

 void OsReleaseSignals (void);

+extern _X_EXPORT void

+OsAbort(void);

+

 #if !defined(WIN32)

 extern int System(char *);

 extern pointer Popen(char *, char *);

Index: xorg-server-1.6.5/os/utils.c

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

--- xorg-server-1.6.5.orig/os/utils.c

+++ xorg-server-1.6.5/os/utils.c

@@ -1345,6 +1345,26 @@ OsReleaseSignals (void)

 #endif

 }

+/*

+ * Pending signals may interfere with core dumping. Provide a

+ * mechanism to block signals when aborting.

+ */

+

+void

+OsAbort(void)

+{

+#ifndef __APPLE__

+    OsBlockSignals();

+#endif

+#if !defined(WIN32) || defined(__CYGWIN__)

+    /* abort() raises SIGABRT, so we have to stop handling that to prevent

+     * recursion

+     */

+    OsSignal(SIGABRT, SIG_DFL);

+#endif

+    abort();

+}

+

 #if !defined(WIN32)

 /*

  * "safer" versions of system(3), popen(3) and pclose(3) which give up