summaryrefslogtreecommitdiff
path: root/deattack.c
diff options
context:
space:
mode:
authorDamien Miller <djm@mindrot.org>1999-11-25 00:26:21 +1100
committerDamien Miller <djm@mindrot.org>1999-11-25 00:26:21 +1100
commit95def09838fc61b37b6ea7cd5c234a465b4b129b (patch)
tree042744f76f40a326b873cb1c3690a6d7d966bc3e /deattack.c
parent4d2f15f895f4c795afc008aeff3fd2ceffbc44f4 (diff)
- Merged very large OpenBSD source code reformat
- OpenBSD CVS updates - [channels.c cipher.c compat.c log-client.c scp.c serverloop.c] [ssh.h sshd.8 sshd.c] syslog changes: * Unified Logmessage for all auth-types, for success and for failed * Standard connections get only ONE line in the LOG when level==LOG: Auth-attempts are logged only, if authentication is: a) successfull or b) with passwd or c) we had more than AUTH_FAIL_LOG failues * many log() became verbose() * old behaviour with level=VERBOSE - [readconf.c readconf.h ssh.1 ssh.h sshconnect.c sshd.c] tranfer s/key challenge/response data in SSH_SMSG_AUTH_TIS_CHALLENGE messages. allows use of s/key in windows (ttssh, securecrt) and ssh-1.2.27 clients without 'ssh -v', ok: niels@ - [sshd.8] -V, for fallback to openssh in SSH2 compatibility mode - [sshd.c] fix sigchld race; cjc5@po.cwru.edu
Diffstat (limited to 'deattack.c')
-rw-r--r--deattack.c238
1 files changed, 106 insertions, 132 deletions
diff --git a/deattack.c b/deattack.c
index afd96e4e..81b1c8ef 100644
--- a/deattack.c
+++ b/deattack.c
@@ -1,5 +1,5 @@
/*
- * $Id: deattack.c,v 1.2 1999/11/08 05:15:55 damien Exp $
+ * $Id: deattack.c,v 1.3 1999/11/24 13:26:22 damien Exp $
* Cryptographic attack detector for ssh - source code
*
* Copyright (c) 1998 CORE SDI S.A., Buenos Aires, Argentina.
@@ -15,7 +15,8 @@
* SOFTWARE.
*
* Ariel Futoransky <futo@core-sdi.com>
- * <http://www.core-sdi.com> */
+ * <http://www.core-sdi.com>
+ */
#include "includes.h"
#include "deattack.h"
@@ -25,157 +26,130 @@
#include "xmalloc.h"
/* SSH Constants */
-#define SSH_MAXBLOCKS (32 * 1024)
-#define SSH_BLOCKSIZE (8)
+#define SSH_MAXBLOCKS (32 * 1024)
+#define SSH_BLOCKSIZE (8)
/* Hashing constants */
-#define HASH_MINSIZE (8 * 1024)
-#define HASH_ENTRYSIZE (2)
-#define HASH_FACTOR(x) ((x)*3/2)
-#define HASH_UNUSEDCHAR (0xff)
-#define HASH_UNUSED (0xffff)
-#define HASH_IV (0xfffe)
+#define HASH_MINSIZE (8 * 1024)
+#define HASH_ENTRYSIZE (2)
+#define HASH_FACTOR(x) ((x)*3/2)
+#define HASH_UNUSEDCHAR (0xff)
+#define HASH_UNUSED (0xffff)
+#define HASH_IV (0xfffe)
-#define HASH_MINBLOCKS (7*SSH_BLOCKSIZE)
+#define HASH_MINBLOCKS (7*SSH_BLOCKSIZE)
/* Hash function (Input keys are cipher results) */
-#define HASH(x) GET_32BIT(x)
+#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
-crc_update(u_int32_t * a, u_int32_t b)
+crc_update(u_int32_t *a, u_int32_t b)
{
- b ^= *a;
- *a = crc32((unsigned char *) &b, sizeof(b));
+ b ^= *a;
+ *a = crc32((unsigned char *) &b, sizeof(b));
}
-/*
- check_crc
- detects if a block is used in a particular pattern
- */
-
+/* detect if a block is used in a particular pattern */
int
-check_crc(unsigned char *S, unsigned char *buf, u_int32_t len, unsigned char *IV)
+check_crc(unsigned char *S, unsigned char *buf, u_int32_t len,
+ unsigned char *IV)
{
- u_int32_t crc;
- unsigned char *c;
-
- crc = 0;
- if (IV && !CMP(S, IV))
- {
- crc_update(&crc, 1);
- crc_update(&crc, 0);
- }
- for (c = buf; c < buf + len; c += SSH_BLOCKSIZE)
- {
- if (!CMP(S, c))
- {
- crc_update(&crc, 1);
- crc_update(&crc, 0);
- } else
- {
- crc_update(&crc, 0);
- crc_update(&crc, 0);
- }
- }
-
- return (crc == 0);
+ u_int32_t crc;
+ unsigned char *c;
+
+ crc = 0;
+ if (IV && !CMP(S, IV)) {
+ crc_update(&crc, 1);
+ crc_update(&crc, 0);
+ }
+ for (c = buf; c < buf + len; c += SSH_BLOCKSIZE) {
+ if (!CMP(S, c)) {
+ crc_update(&crc, 1);
+ crc_update(&crc, 0);
+ } else {
+ crc_update(&crc, 0);
+ crc_update(&crc, 0);
+ }
+ }
+ return (crc == 0);
}
-/*
- detect_attack
- Detects a crc32 compensation attack on a packet
- */
+/* Detect a crc32 compensation attack on a packet */
int
detect_attack(unsigned char *buf, u_int32_t len, unsigned char *IV)
{
- static u_int16_t *h = (u_int16_t *) NULL;
- static u_int16_t n = HASH_MINSIZE / HASH_ENTRYSIZE;
- register u_int32_t i, j;
- u_int32_t l;
- register unsigned char *c;
- unsigned char *d;
-
- if (len > (SSH_MAXBLOCKS * SSH_BLOCKSIZE) ||
- len % SSH_BLOCKSIZE != 0) {
- fatal("detect_attack: bad length %d", len);
- }
-
- for (l = n; l < HASH_FACTOR(len / SSH_BLOCKSIZE); l = l << 2);
-
- if (h == NULL)
- {
- debug("Installing crc compensation attack detector.");
- n = l;
- h = (u_int16_t *) xmalloc(n * HASH_ENTRYSIZE);
- } else
- {
- if (l > n)
- {
- n = l;
- h = (u_int16_t *) xrealloc(h, n * HASH_ENTRYSIZE);
- }
- }
-
-
- if (len <= HASH_MINBLOCKS)
- {
- for (c = buf; c < buf + len; c += SSH_BLOCKSIZE)
- {
- if (IV && (!CMP(c, IV)))
- {
- if ((check_crc(c, buf, len, IV)))
- return (DEATTACK_DETECTED);
- else
- break;
- }
- for (d = buf; d < c; d += SSH_BLOCKSIZE)
- {
- if (!CMP(c, d))
- {
- if ((check_crc(c, buf, len, IV)))
- return (DEATTACK_DETECTED);
- else
- break;
+ static u_int16_t *h = (u_int16_t *) NULL;
+ static u_int16_t n = HASH_MINSIZE / HASH_ENTRYSIZE;
+ register u_int32_t i, j;
+ u_int32_t l;
+ register unsigned char *c;
+ unsigned char *d;
+
+ if (len > (SSH_MAXBLOCKS * SSH_BLOCKSIZE) ||
+ len % SSH_BLOCKSIZE != 0) {
+ fatal("detect_attack: bad length %d", len);
+ }
+ for (l = n; l < HASH_FACTOR(len / SSH_BLOCKSIZE); l = l << 2)
+ ;
+
+ if (h == NULL) {
+ debug("Installing crc compensation attack detector.");
+ n = l;
+ h = (u_int16_t *) xmalloc(n * HASH_ENTRYSIZE);
+ } else {
+ if (l > n) {
+ n = l;
+ h = (u_int16_t *) xrealloc(h, n * HASH_ENTRYSIZE);
+ }
+ }
+
+ if (len <= HASH_MINBLOCKS) {
+ for (c = buf; c < buf + len; c += SSH_BLOCKSIZE) {
+ if (IV && (!CMP(c, IV))) {
+ if ((check_crc(c, buf, len, IV)))
+ return (DEATTACK_DETECTED);
+ else
+ break;
+ }
+ for (d = buf; d < c; d += SSH_BLOCKSIZE) {
+ if (!CMP(c, d)) {
+ if ((check_crc(c, buf, len, IV)))
+ return (DEATTACK_DETECTED);
+ else
+ break;
+ }
+ }
+ }
+ return (DEATTACK_OK);
}
- }
- }
- return (DEATTACK_OK);
- }
- memset(h, HASH_UNUSEDCHAR, n * HASH_ENTRYSIZE);
-
- if (IV)
- h[HASH(IV) & (n - 1)] = HASH_IV;
-
-
- 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))
- {
- if (h[i] == HASH_IV)
- {
- if (!CMP(c, IV))
- {
- if (check_crc(c, buf, len, IV))
- return (DEATTACK_DETECTED);
- else
- break;
+ memset(h, HASH_UNUSEDCHAR, n * HASH_ENTRYSIZE);
+
+ if (IV)
+ h[HASH(IV) & (n - 1)] = HASH_IV;
+
+ 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)) {
+ if (h[i] == HASH_IV) {
+ if (!CMP(c, IV)) {
+ if (check_crc(c, buf, len, IV))
+ return (DEATTACK_DETECTED);
+ else
+ break;
+ }
+ } else if (!CMP(c, buf + h[i] * SSH_BLOCKSIZE)) {
+ if (check_crc(c, buf, len, IV))
+ return (DEATTACK_DETECTED);
+ else
+ break;
+ }
+ }
+ h[i] = j;
}
- } else if (!CMP(c, buf + h[i] * SSH_BLOCKSIZE))
- {
- if (check_crc(c, buf, len, IV))
- return (DEATTACK_DETECTED);
- else
- break;
- }
- }
- h[i] = j;
- }
-
- return (DEATTACK_OK);
+ return (DEATTACK_OK);
}