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

4 files changed, 32 insertions, 55 deletions

diff --git a/lib/libc/stdlib/rand.3 b/lib/libc/stdlib/rand.3
index 390a40b..bf50e3d 100644
--- a/lib/libc/stdlib/rand.3
+++ b/lib/libc/stdlib/rand.3
@@ -32,7 +32,7 @@
 .\"     @(#)rand.3	8.1 (Berkeley) 6/4/93
 .\" $FreeBSD$
 .\"
-.Dd September 4, 2012
+.Dd April 2, 2013
 .Dt RAND 3
 .Os
 .Sh NAME
@@ -91,9 +91,7 @@ seeded with a value of 1.
 .Pp
 The
 .Fn sranddev
-function initializes a seed using the
-.Xr random 4
-random number device which returns good random numbers.
+function initializes a seed using pseudo-random numbers obtained from the kernel.
 .Pp
 The
 .Fn rand_r
diff --git a/lib/libc/stdlib/rand.c b/lib/libc/stdlib/rand.c
index 7041818..0cbd948 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);
 }
 
 
diff --git a/lib/libc/stdlib/random.3 b/lib/libc/stdlib/random.3
index 4817440..a1e585b 100644
--- a/lib/libc/stdlib/random.3
+++ b/lib/libc/stdlib/random.3
@@ -28,7 +28,7 @@
 .\"     @(#)random.3	8.1 (Berkeley) 6/4/93
 .\" $FreeBSD$
 .\"
-.Dd September 4, 2012
+.Dd April 2, 2013
 .Dt RANDOM 3
 .Os
 .Sh NAME
@@ -106,8 +106,8 @@ as the seed.
 .Pp
 The
 .Fn srandomdev
-routine initializes a state array using data from
-.Xr random 4 .
+routine initializes a state array using
+pseudo-random numbers obtained from the kernel.
 Note that this particular seeding
 procedure can generate states which are impossible to reproduce by
 calling
diff --git a/lib/libc/stdlib/random.c b/lib/libc/stdlib/random.c
index a3c054e..4c88ecb 100644
--- a/lib/libc/stdlib/random.c
+++ b/lib/libc/stdlib/random.c
@@ -34,12 +34,11 @@ static char sccsid[] = "@(#)random.c	8.2 (Berkeley) 5/19/95";
 __FBSDID("$FreeBSD$");
 
 #include "namespace.h"
-#include <sys/time.h>          /* for srandomdev() */
-#include <fcntl.h>             /* for srandomdev() */
+#include <sys/param.h>
+#include <sys/sysctl.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <unistd.h>            /* for srandomdev() */
 #include "un-namespace.h"
 
 /*
@@ -284,39 +283,28 @@ srandom(unsigned long x)
  * srandomdev:
  *
  * 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.  Note that this particular seeding
- * procedure can generate states which are impossible to reproduce by
- * calling srandom() with any value, since the succeeding terms in the
- * state buffer are no longer derived from the LC algorithm applied to
- * a fixed seed.
+ * This often causes problems.  We seed the generator using pseudo-random
+ * data from the kernel.
+ *
+ * Note that this particular seeding procedure can generate states
+ * which are impossible to reproduce by calling srandom() with any
+ * value, since the succeeding terms in the state buffer are no longer
+ * derived from the LC algorithm applied to a fixed seed.
  */
 void
 srandomdev(void)
 {
-	int fd, done;
+	int mib[2];
 	size_t len;
 
 	if (rand_type == TYPE_0)
-		len = sizeof state[0];
+		len = sizeof(state[0]);
 	else
-		len = rand_deg * sizeof state[0];
-
-	done = 0;
-	fd = _open("/dev/random", O_RDONLY | O_CLOEXEC, 0);
-	if (fd >= 0) {
-		if (_read(fd, (void *) state, len) == (ssize_t) len)
-			done = 1;
-		_close(fd);
-	}
+		len = rand_deg * sizeof(state[0]);
 
-	if (!done) {
-		struct timeval tv;
-
-		gettimeofday(&tv, NULL);
-		srandom((getpid() << 16) ^ tv.tv_sec ^ tv.tv_usec);
-		return;
-	}
+	mib[0] = CTL_KERN;
+	mib[1] = KERN_ARND;
+	sysctl(mib, 2, state, &len, NULL, 0);
 
 	if (rand_type != TYPE_0) {
 		fptr = &state[rand_sep];