-/* $OpenBSD: deattack.c,v 1.11 2000/12/19 23:17:56 markus Exp $ */
-
/*
* Cryptographic attack detector for ssh - source code
*
*/
#include "includes.h"
+RCSID("$OpenBSD: deattack.c,v 1.19 2003/09/18 08:49:45 markus Exp $");
+
#include "deattack.h"
-#include "ssh.h"
+#include "log.h"
#include "crc32.h"
#include "getput.h"
#include "xmalloc.h"
+#include "deattack.h"
/* SSH Constants */
#define SSH_MAXBLOCKS (32 * 1024)
#define HASH_FACTOR(x) ((x)*3/2)
#define HASH_UNUSEDCHAR (0xff)
#define HASH_UNUSED (0xffff)
-#define HASH_IV (0xfffe)
+#define HASH_IV (0xfffe)
#define HASH_MINBLOCKS (7*SSH_BLOCKSIZE)
/* Hash function (Input keys are cipher results) */
#define HASH(x) GET_32BIT(x)
-#define CMP(a,b) (memcmp(a, b, SSH_BLOCKSIZE))
+#define CMP(a, b) (memcmp(a, b, SSH_BLOCKSIZE))
-
-void
+static void
crc_update(u_int32_t *a, u_int32_t b)
{
b ^= *a;
}
/* detect if a block is used in a particular pattern */
-int
+static int
check_crc(u_char *S, u_char *buf, u_int32_t len,
u_char *IV)
{
{
static u_int16_t *h = (u_int16_t *) NULL;
static u_int32_t n = HASH_MINSIZE / HASH_ENTRYSIZE;
- register u_int32_t i, j;
+ u_int32_t i, j;
u_int32_t l;
- register u_char *c;
+ u_char *c;
u_char *d;
if (len > (SSH_MAXBLOCKS * SSH_BLOCKSIZE) ||
if (h == NULL) {
debug("Installing crc compensation attack detector.");
+ h = (u_int16_t *) xmalloc(l * HASH_ENTRYSIZE);
n = l;
- h = (u_int16_t *) xmalloc(n * HASH_ENTRYSIZE);
} else {
if (l > n) {
+ h = (u_int16_t *) xrealloc(h, l * HASH_ENTRYSIZE);
n = l;
- h = (u_int16_t *) xrealloc(h, n * HASH_ENTRYSIZE);
}
}
for (c = buf, j = 0; c < (buf + len); c += SSH_BLOCKSIZE, j++) {
for (i = HASH(c) & (n - 1); h[i] != HASH_UNUSED;
- i = (i + 1) & (n - 1)) {
+ i = (i + 1) & (n - 1)) {
if (h[i] == HASH_IV) {
if (!CMP(c, IV)) {
if (check_crc(c, buf, len, IV))