freebsd-dev/contrib/ipfilter/arc4random.c
Cy Schubert 0fcd8cab4e ipfilter #ifdef cleanup.
Remove #ifdefs for ancient and irrelevant operating systems from
ipfilter.

When ipfilter was written the UNIX and UNIX-like systems in use
were diverse and plentiful. IRIX, Tru64 (OSF/1) don't exist any
more. OpenBSD removed ipfilter shortly after the first time the
ipfilter license terms changed in the early 2000's. ipfilter on AIX,
HP/UX, and Linux never really caught on. Removal of code for operating
systems that ipfilter will never run on again will simplify the code
making it easier to fix bugs, complete partially implemented features,
and extend ipfilter.

Unsupported previous version FreeBSD code and some older NetBSD code
has also been removed.

What remains is supported FreeBSD, NetBSD, and illumos. FreeBSD and
NetBSD have collaborated exchanging patches, while illumos has expressed
willingness to have their ipfilter updated to 5.1.2, provided their
zone-specific updates to their ipfilter are merged (which are of interest
to FreeBSD to allow control of ipfilters in jails from the global zone).

Reviewed by:	glebius@
MFC after:	1 month
Differential Revision:	https://reviews.freebsd.org/D19006
2019-02-03 05:25:49 +00:00

268 lines
5.0 KiB
C

/*-
* THE BEER-WARE LICENSE
*
* <dan@FreeBSD.ORG> wrote this file. As long as you retain this notice you
* can do whatever you want with this stuff. If we meet some day, and you
* think this stuff is worth it, you can buy me a beer in return.
*
* Dan Moschuk
*/
#if !defined(SOLARIS2)
# include <sys/cdefs.h>
#endif
#include <sys/types.h>
#include <sys/param.h>
#ifdef __FreeBSD__
# include <sys/kernel.h>
#endif
# include <sys/random.h>
#ifdef __FreeBSD__
# include <sys/libkern.h>
#endif
#include <sys/lock.h>
# include <sys/mutex.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include "netinet/ip_compat.h"
#ifdef HAS_SYS_MD5_H
# include <sys/md5.h>
#else
# include "md5.h"
#endif
#ifdef NEED_LOCAL_RAND
#if !defined(__GNUC__)
# define __inline
#endif
#define ARC4_RESEED_BYTES 65536
#define ARC4_RESEED_SECONDS 300
#define ARC4_KEYBYTES (256 / 8)
static u_int8_t arc4_i, arc4_j;
static int arc4_numruns = 0;
static u_int8_t arc4_sbox[256];
static time_t arc4_t_reseed;
static ipfmutex_t arc4_mtx;
static MD5_CTX md5ctx;
static u_int8_t arc4_randbyte(void);
static int ipf_read_random(void *dest, int length);
static __inline void
arc4_swap(u_int8_t *a, u_int8_t *b)
{
u_int8_t c;
c = *a;
*a = *b;
*b = c;
}
/*
* Stir our S-box.
*/
static void
arc4_randomstir (void)
{
u_int8_t key[256];
int r, n;
struct timeval tv_now;
/*
* XXX read_random() returns unsafe numbers if the entropy
* device is not loaded -- MarkM.
*/
r = ipf_read_random(key, ARC4_KEYBYTES);
GETKTIME(&tv_now);
MUTEX_ENTER(&arc4_mtx);
/* If r == 0 || -1, just use what was on the stack. */
if (r > 0) {
for (n = r; n < sizeof(key); n++)
key[n] = key[n % r];
}
for (n = 0; n < 256; n++) {
arc4_j = (arc4_j + arc4_sbox[n] + key[n]) % 256;
arc4_swap(&arc4_sbox[n], &arc4_sbox[arc4_j]);
}
/* Reset for next reseed cycle. */
arc4_t_reseed = tv_now.tv_sec + ARC4_RESEED_SECONDS;
arc4_numruns = 0;
/*
* Throw away the first N words of output, as suggested in the
* paper "Weaknesses in the Key Scheduling Algorithm of RC4"
* by Fluher, Mantin, and Shamir. (N = 768 in our case.)
*/
for (n = 0; n < 768*4; n++)
arc4_randbyte();
MUTEX_EXIT(&arc4_mtx);
}
/*
* Initialize our S-box to its beginning defaults.
*/
static void
arc4_init(void)
{
int n;
MD5Init(&md5ctx);
MUTEX_INIT(&arc4_mtx, "arc4_mtx");
arc4_i = arc4_j = 0;
for (n = 0; n < 256; n++)
arc4_sbox[n] = (u_int8_t) n;
arc4_t_reseed = 0;
}
/*
* Generate a random byte.
*/
static u_int8_t
arc4_randbyte(void)
{
u_int8_t arc4_t;
arc4_i = (arc4_i + 1) % 256;
arc4_j = (arc4_j + arc4_sbox[arc4_i]) % 256;
arc4_swap(&arc4_sbox[arc4_i], &arc4_sbox[arc4_j]);
arc4_t = (arc4_sbox[arc4_i] + arc4_sbox[arc4_j]) % 256;
return arc4_sbox[arc4_t];
}
/*
* MPSAFE
*/
void
arc4rand(void *ptr, u_int len, int reseed)
{
u_int8_t *p;
struct timeval tv;
GETKTIME(&tv);
if (reseed ||
(arc4_numruns > ARC4_RESEED_BYTES) ||
(tv.tv_sec > arc4_t_reseed))
arc4_randomstir();
MUTEX_ENTER(&arc4_mtx);
arc4_numruns += len;
p = ptr;
while (len--)
*p++ = arc4_randbyte();
MUTEX_EXIT(&arc4_mtx);
}
uint32_t
ipf_random(void)
{
uint32_t ret;
arc4rand(&ret, sizeof ret, 0);
return ret;
}
static u_char pot[ARC4_RESEED_BYTES];
static u_char *pothead = pot, *pottail = pot;
static int inpot = 0;
/*
* This is not very strong, and this is understood, but the aim isn't to
* be cryptographically strong - it is just to make up something that is
* pseudo random.
*/
void
ipf_rand_push(void *src, int length)
{
static int arc4_inited = 0;
u_char *nsrc;
int mylen;
if (arc4_inited == 0) {
arc4_init();
arc4_inited = 1;
}
if (length < 64) {
MD5Update(&md5ctx, src, length);
return;
}
nsrc = src;
mylen = length;
#if defined(_SYS_MD5_H) && defined(SOLARIS2)
# define buf buf_un.buf8
#endif
MUTEX_ENTER(&arc4_mtx);
while ((mylen > 64) && (sizeof(pot) - inpot > sizeof(md5ctx.buf))) {
MD5Update(&md5ctx, nsrc, 64);
mylen -= 64;
nsrc += 64;
if (pottail + sizeof(md5ctx.buf) > pot + sizeof(pot)) {
int left, numbytes;
numbytes = pot + sizeof(pot) - pottail;
bcopy(md5ctx.buf, pottail, numbytes);
left = sizeof(md5ctx.buf) - numbytes;
pottail = pot;
bcopy(md5ctx.buf + sizeof(md5ctx.buf) - left,
pottail, left);
pottail += left;
} else {
bcopy(md5ctx.buf, pottail, sizeof(md5ctx.buf));
pottail += sizeof(md5ctx.buf);
}
inpot += 64;
}
MUTEX_EXIT(&arc4_mtx);
#if defined(_SYS_MD5_H) && defined(SOLARIS2)
# undef buf
#endif
}
static int
ipf_read_random(void *dest, int length)
{
if (length > inpot)
return 0;
MUTEX_ENTER(&arc4_mtx);
if (pothead + length > pot + sizeof(pot)) {
int left, numbytes;
left = length;
numbytes = pot + sizeof(pot) - pothead;
bcopy(pothead, dest, numbytes);
left -= numbytes;
pothead = pot;
bcopy(pothead, dest + length - left, left);
pothead += left;
} else {
bcopy(pothead, dest, length);
pothead += length;
}
inpot -= length;
if (inpot == 0)
pothead = pottail = pot;
MUTEX_EXIT(&arc4_mtx);
return length;
}
#endif /* NEED_LOCAL_RAND */