Replace access to /dev/random with the kernel pseudo-random number

source sysctl(KERN_ARND) and remove the fallback code.

Obtained from:	OpenBSD
Reviewed by:	secteam
MFC after:	1 month

1 files changed, 12 insertions, 21 deletions

diff --git a/lib/libc/stdlib/rand.c b/lib/libc/stdlib/rand.c
index 704181890bb7..0cbd94883125 100644
--- a/lib/libc/stdlib/rand.c
+++ b/lib/libc/stdlib/rand.c
@@ -36,11 +36,10 @@ static char sccsid[] = "@(#)rand.c	8.1 (Berkeley) 6/14/93";
 __FBSDID("$FreeBSD$");
 
 #include "namespace.h"
-#include <sys/time.h>          /* for sranddev() */
+#include <sys/param.h>
+#include <sys/sysctl.h>
 #include <sys/types.h>
-#include <fcntl.h>             /* for sranddev() */
 #include <stdlib.h>
-#include <unistd.h>            /* for sranddev() */
 #include "un-namespace.h"
 
 #ifdef TEST
@@ -112,28 +111,20 @@ u_int seed;
  * sranddev:
  *
  * Many programs choose the seed value in a totally predictable manner.
- * This often causes problems.  We seed the generator using the much more
- * secure random(4) interface.
+ * This often causes problems.  We seed the generator using pseudo-random
+ * data from the kernel.
  */
 void
 sranddev()
 {
-	int fd, done;
-
-	done = 0;
-	fd = _open("/dev/random", O_RDONLY | O_CLOEXEC, 0);
-	if (fd >= 0) {
-		if (_read(fd, (void *) &next, sizeof(next)) == sizeof(next))
-			done = 1;
-		_close(fd);
-	}
-
-	if (!done) {
-		struct timeval tv;
-
-		gettimeofday(&tv, NULL);
-		srand((getpid() << 16) ^ tv.tv_sec ^ tv.tv_usec);
-	}
+	int mib[2];
+	size_t len;
+
+	len = sizeof(next);
+
+	mib[0] = CTL_KERN;
+	mib[1] = KERN_ARND;
+	sysctl(mib, 2, (void *)&next, &len, NULL, 0);
 }