Stefan Dirsch
5df1139ec3
* This release contains fixes for CVE-2023-5367 and CVE-2023-5380 as
reported in today's security advisory:
https://lists.x.org/archives/xorg-announce/2023-October/003430.html
- adjusted u_Use-better-fallbacks-to-generate-cookies-if-arc4rand.patch
OBS-URL: https://build.opensuse.org/package/show/X11:XOrg/xorg-x11-server?expand=0&rev=859
225 lines
6.1 KiB
Diff
225 lines
6.1 KiB
Diff
From 44a643812ce3c07cd38972abfa9dbd163529c192 Mon Sep 17 00:00:00 2001
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From: Matthias Gerstner <mgerstner@suse.de>
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Date: Thu, 13 Jul 2017 14:58:04 +0200
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Subject: [PATCH] Use better fallbacks to generate cookies if arc4random_buf(3)
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is unavailable
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References: bsc#1025084
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If arc4random_buf() is not available for generating cookies:
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- use getentropy(), if available (which was only recently added to
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glibc)
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- use getrandom() via syscall(), if available (there was no glibc
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wrapper for this syscall for a long time)
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- if all else fails, directly read from /dev/urandom as before, but
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employ O_CLOEXEC, do an OsAbort() in case the random data couldn't be
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read to avoid unsecure situations. Don't know if that's too hard a
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measure but it shouldn't actually occur except on maximum number of
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FDs reached
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Reviewed-by: Stefan Dirsch <sndirsch@suse.de>
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---
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configure.ac | 4 +-
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include/dix-config.h.in | 6 +++
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os/auth.c | 138 ++++++++++++++++++++++++++++++++++++++++++++++--
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3 files changed, 141 insertions(+), 7 deletions(-)
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Index: xorg-server-21.1.9/configure.ac
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===================================================================
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--- xorg-server-21.1.9.orig/configure.ac
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+++ xorg-server-21.1.9/configure.ac
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@@ -132,7 +132,7 @@ AM_CONDITIONAL(SPECIAL_DTRACE_OBJECTS, [
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AC_HEADER_DIRENT
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AC_HEADER_STDC
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AC_CHECK_HEADERS([fcntl.h stdlib.h string.h unistd.h dlfcn.h stropts.h \
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- fnmatch.h sys/mkdev.h sys/sysmacros.h sys/utsname.h])
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+ fnmatch.h sys/mkdev.h sys/sysmacros.h sys/utsname.h sys/syscall.h])
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dnl Checks for typedefs, structures, and compiler characteristics.
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AC_C_CONST
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Index: xorg-server-21.1.9/include/dix-config.h.in
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===================================================================
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--- xorg-server-21.1.9.orig/include/dix-config.h.in
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+++ xorg-server-21.1.9/include/dix-config.h.in
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@@ -149,6 +149,9 @@
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/* Define to 1 if you have the `arc4random_buf' function. */
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#undef HAVE_ARC4RANDOM_BUF
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+/* Define to 1 if you have the `getentropy' function. */
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+#undef HAVE_GETENTROPY
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+
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/* Define to use libc SHA1 functions */
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#undef HAVE_SHA1_IN_LIBC
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@@ -226,6 +229,9 @@
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/* Define to 1 if you have the <sys/utsname.h> header file. */
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#undef HAVE_SYS_UTSNAME_H
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+/* Define to 1 if you have the <sys/syscall.h> header file. */
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+#undef HAVE_SYS_SYSCALL_H
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+
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/* Define to 1 if you have the `timingsafe_memcmp' function. */
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#undef HAVE_TIMINGSAFE_MEMCMP
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Index: xorg-server-21.1.9/os/auth.c
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===================================================================
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--- xorg-server-21.1.9.orig/os/auth.c
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+++ xorg-server-21.1.9/os/auth.c
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@@ -34,6 +34,10 @@ from The Open Group.
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#ifdef HAVE_DIX_CONFIG_H
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#include <dix-config.h>
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#endif
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+#include <errno.h>
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+#ifdef HAVE_SYS_SYSCALL_H
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+#include <syscall.h>
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+#endif
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#include <X11/X.h>
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#include <X11/Xauth.h>
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@@ -308,16 +312,140 @@ GenerateAuthorization(unsigned name_leng
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#endif /* XCSECURITY */
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+#if ! defined(HAVE_ARC4RANDOM_BUF)
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+
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+// fallback function to get random data directly from /dev/urandom
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+
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+static int
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+GetUrandom ( char *buffer, size_t length )
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+{
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+ int random_fd = -1;
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+ int res = -1;
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+ size_t filled = 0;
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+
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+ // larger requests are typically rejected by getentropy() / getrandom()
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+ // because they could block or return partially filled buffers
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+ if( length > 256 ) {
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+ errno = EIO;
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+ return -1;
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+ }
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+
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+ random_fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC);
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+
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+ if( random_fd == -1 ) {
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+ return -1;
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+ }
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+
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+ while( filled < length ) {
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+ res = read(random_fd, (char*)buffer + filled, length - filled);
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+
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+ if( res == -1 ) {
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+ // shouldn't actually happen acc. to man(4) random,
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+ // but you never know
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+ if( errno == EINTR ) {
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+ continue;
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+ }
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+
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+ res = errno;
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+ close(random_fd);
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+ errno = res;
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+ return -1;
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+ }
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+ else if( res == 0 ) {
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+ close(random_fd);
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+ // no more bytes available? should not happen
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+ errno = EIO;
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+ return -1;
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+ }
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+
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+ filled += res;
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+ }
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+
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+ close(random_fd);
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+
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+ return 0;
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+}
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+
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+#endif // ! defined(HAVE_ARC4RANDOM_BUF)
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+
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+#if !defined(HAVE_GETENTROPY) && defined(HAVE_SYS_SYSCALL_H) && defined(SYS_getrandom)
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+# define TRY_GETRANDOM
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+#endif
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+
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+#ifdef TRY_GETRANDOM
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+
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+/*
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+ * wrapper for the getrandom() syscall which was for a long time implemented
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+ * in the Linux kernel, but not wrapped in glibc
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+ */
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+static int
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+GetRandom ( char *buffer, size_t length )
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+{
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+ int res;
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+ size_t filled = 0;
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+
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+ // larger requests are typically rejected by getentropy() / getrandom()
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+ // because they could block or return partially filled buffers
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+ if( length > 256 )
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+ {
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+ errno = EIO;
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+ return -1;
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+ }
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+
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+ while( filled < length )
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+ {
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+ /*
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+ * glibc does not contain a syscall wrapper for this in older
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+ * versions
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+ */
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+ res = syscall(SYS_getrandom, (char*)buffer + filled, length - filled, 0);
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+
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+ if( res == -1 )
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+ {
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+ if( errno == EINTR ) {
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+ continue;
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+ }
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+
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+ return -1;
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+ }
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+ else if( res == 0 )
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+ {
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+ // no more bytes available? should not happen
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+ errno = EIO;
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+ return -1;
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+ }
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+
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+ filled += res;
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+ }
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+
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+ return 0;
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+}
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+
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+#endif /* TRY_GETRANDOM */
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+
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void
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GenerateRandomData(int len, char *buf)
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{
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#ifdef HAVE_ARC4RANDOM_BUF
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arc4random_buf(buf, len);
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#else
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- int fd;
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+ int ret = -1;
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+# ifdef HAVE_GETENTROPY
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+ /* use getentropy instead */
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+ ret = getentropy (buf, len);
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+# elif defined(TRY_GETRANDOM)
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+ /* try getrandom() wrapper */
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+ ret = GetRandom(buf, len);
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+# endif
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+
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+ if( ret == -1 ) {
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+ // fallback to manual reading of /dev/urandom
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+ ret = GetUrandom(buf, len);
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+ }
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- fd = open("/dev/urandom", O_RDONLY);
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- read(fd, buf, len);
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- close(fd);
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-#endif
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+ if( ret == -1 ) {
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+ // no error return possible, rather abort than have security problems
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+ OsAbort();
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+ }
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+#endif // HAVE_ARC4RANDOM_BUF
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}
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