From 2040d4dde54a8ca0840b5b76b2e3e665af7c09fb Mon Sep 17 00:00:00 2001
From: "Todd C. Miller" <Todd.Miller@courtesan.com>
Date: Fri, 31 Oct 2014 06:57:19 -0600
Subject: [PATCH] Use arc4random() for mkstemp/mkdtemp if available.  If not,
 try to seed from /dev/urandom before falling back to the gettimeofday seed.

---
 config.h.in       |  3 +++
 configure         |  2 +-
 configure.ac      |  2 +-
 lib/util/mktemp.c | 58 ++++++++++++++++++++++++++++++++---------------
 4 files changed, 45 insertions(+), 20 deletions(-)

diff --git a/config.h.in b/config.h.in
index 0acb6d1fe..0b0234a1b 100644
--- a/config.h.in
+++ b/config.h.in
@@ -52,6 +52,9 @@
 /* Define to 1 if you use AIX general authentication. */
 #undef HAVE_AIXAUTH
 
+/* Define to 1 if you have the `arc4random' function. */
+#undef HAVE_ARC4RANDOM
+
 /* Define to 1 if you have the `asprintf' function. */
 #undef HAVE_ASPRINTF
 
diff --git a/configure b/configure
index b0b21aab7..7310c3f1d 100755
--- a/configure
+++ b/configure
@@ -18401,7 +18401,7 @@ fi
 done
 
 if test X"$ac_cv_func_mkstemps$ac_cv_func_mkdtemp" != X"yesyes"; then
-    for ac_func in random lrand48
+    for ac_func in arc4random random lrand48
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
diff --git a/configure.ac b/configure.ac
index 546b98126..f4fa0c775 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2520,7 +2520,7 @@ AC_CHECK_FUNCS(closefrom, [], [AC_LIBOBJ(closefrom)
 ])
 AC_CHECK_FUNCS(mkstemps mkdtemp, [], [break])
 if test X"$ac_cv_func_mkstemps$ac_cv_func_mkdtemp" != X"yesyes"; then
-    AC_CHECK_FUNCS(random lrand48, [break])
+    AC_CHECK_FUNCS(arc4random random lrand48, [break])
     AC_LIBOBJ(mktemp)
     # If either mkdtemp() or mkstemps() is missing, replace both.
     SUDO_APPEND_COMPAT_EXP(sudo_mkdtemp sudo_mkstemps)
diff --git a/lib/util/mktemp.c b/lib/util/mktemp.c
index 87ed760fa..50ce6ccda 100644
--- a/lib/util/mktemp.c
+++ b/lib/util/mktemp.c
@@ -50,35 +50,57 @@
 #define INT_MAX	0x7fffffff
 #endif
 
-#ifdef HAVE_RANDOM
-# define RAND		random
-# define SRAND		srandom
+#if defined(HAVE_ARC4RANDOM)
+# define RAND()		arc4random()
 # define SEED_T		unsigned int
+#elif defined(HAVE_RANDOM)
+# define RAND()		random()
+# define SRAND(_x)	srandom((_x))
+# define SEED_T		unsigned int
+#elif defined(HAVE_LRAND48)
+# define RAND()		lrand48()
+# define SRAND(_x)	srand48((_x))
+# define SEED_T		long
 #else
-# ifdef HAVE_LRAND48
-#  define RAND		lrand48
-#  define SRAND		srand48
-#  define SEED_T	long
-# else
-#  define RAND		rand
-#  define SRAND		srand
-#  define SEED_T	unsigned int
-# endif
+# define RAND()		rand()
+# define SRAND(_x)	srand((_x))
+# define SEED_T		unsigned int
 #endif
 
 static void
 seed_random(void)
 {
-	SEED_T seed;
+#ifdef SRAND
 	struct timeval tv;
+	SEED_T seed;
+	int fd;
 
 	/*
-	 * Seed from time of day and process id multiplied by small primes.
+	 * Seed from /dev/urandom if possible.
 	 */
-	(void) gettimeofday(&tv, NULL);
-	seed = (tv.tv_sec % 10000) * 523 + tv.tv_usec * 13 +
-	    (getpid() % 1000) * 983;
+	fd = open("/dev/urandom", O_RDONLY);
+	if (fd != -1) {
+	    ssize_t nread;
+
+	    do {
+		nread = read(fd, &seed, sizeof(seed));
+	    } while (nread == -1 && errno == EINTR);
+	    close(fd);
+	    if (nread != (ssize_t)sizeof(seed))
+		fd = -1;
+	}
+
+	/*
+	 * If no /dev/urandom, seed from time of day and process id
+	 * multiplied by small primes.
+	 */
+	if (fd == -1) {
+	    (void) gettimeofday(&tv, NULL);
+	    seed = (tv.tv_sec % 10000) * 523 + tv.tv_usec * 13 +
+		(getpid() % 1000) * 983;
+	}
 	SRAND(seed);
+#endif
 }
 
 static unsigned int
@@ -98,7 +120,7 @@ static int
 mktemp_internal(char *path, int slen, int mode)
 {
 	char *start, *cp, *ep;
-	const char *tempchars = TEMPCHARS;
+	const char tempchars[] = TEMPCHARS;
 	unsigned int r, tries;
 	int fd;
 
-- 
2.40.0