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

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source sysctl(KERN_ARND) and remove the fallback code.

Obtained from:	OpenBSD
Reviewed by:	secteam
MFC after:	1 month
This commit is contained in:
Xin LI 2013-04-02 23:41:20 +00:00
parent c6a453a430
commit 12a6865090
4 changed files with 30 additions and 53 deletions
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6
lib/libc/stdlib/rand.3
View File

@ -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

29
lib/libc/stdlib/rand.c
View File

@ -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;
int mib[2];
size_t len;
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);
}
len = sizeof(next);
if (!done) {
struct timeval tv;
gettimeofday(&tv, NULL);
srand((getpid() << 16) ^ tv.tv_sec ^ tv.tv_usec);
}
mib[0] = CTL_KERN;
mib[1] = KERN_ARND;
sysctl(mib, 2, (void *)&next, &len, NULL, 0);
}

6
lib/libc/stdlib/random.3
View File

@ -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

42
lib/libc/stdlib/random.c
View File

@ -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];
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);
}
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];