[deattack.c deattack.h]

     remove IV support from the CRC attack detector, OpenSSH has never used
     it - it only applied to IDEA-CFB, which we don't support.
     prompted by NetBSD Coverity report via elad AT netbsd.org;
     feedback markus@ "nuke it" deraadt@

3 files changed, 15 insertions, 30 deletions

diff --git a/ChangeLog b/ChangeLog
index b3298fe0a..3bc8c4bd3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -56,6 +56,12 @@
    - jakob@cvs.openbsd.org 2006/03/22 21:16:24
      [ssh.1]
      simplify SSHFP example; ok jmc@
+   - djm@cvs.openbsd.org 2006/03/22 21:27:15
+     [deattack.c deattack.h]
+     remove IV support from the CRC attack detector, OpenSSH has never used
+     it - it only applied to IDEA-CFB, which we don't support.
+     prompted by NetBSD Coverity report via elad AT netbsd.org;
+     feedback markus@ "nuke it" deraadt@
 
 20060318
  - (djm) [auth-pam.c] Fix memleak in error path, from Coverity via
@@ -4248,4 +4254,4 @@
    - (djm) Trim deprecated options from INSTALL. Mention UsePAM
    - (djm) Fix quote handling in sftp; Patch from admorten AT umich.edu
 
-$Id: ChangeLog,v 1.4240 2006/03/25 13:07:02 djm Exp $
+$Id: ChangeLog,v 1.4241 2006/03/25 13:11:46 djm Exp $
diff --git a/deattack.c b/deattack.c
index 3d48afc89..bf4451b88 100644
--- a/deattack.c
+++ b/deattack.c
@@ -49,22 +49,17 @@ static void
 crc_update(u_int32_t *a, u_int32_t b)
 {
         b ^= *a;
-        *a = ssh_crc32((u_char *) &b, sizeof(b));
+        *a = ssh_crc32((u_char *)&b, sizeof(b));
 }
 
 /* detect if a block is used in a particular pattern */
 static int
-check_crc(u_char *S, u_char *buf, u_int32_t len,
-          u_char *IV)
+check_crc(u_char *S, u_char *buf, u_int32_t len)
 {
         u_int32_t crc;
         u_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);
@@ -80,7 +75,7 @@ check_crc(u_char *S, u_char *buf, u_int32_t len,
 
 /* Detect a crc32 compensation attack on a packet */
 int
-detect_attack(u_char *buf, u_int32_t len, u_char *IV)
+detect_attack(u_char *buf, u_int32_t len)
 {
         static u_int16_t *h = (u_int16_t *) NULL;
         static u_int32_t n = HASH_MINSIZE / HASH_ENTRYSIZE;
@@ -109,15 +104,9 @@ detect_attack(u_char *buf, u_int32_t len, u_char *IV)
 
         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)))
+                                        if ((check_crc(c, buf, len)))
                                                 return (DEATTACK_DETECTED);
                                         else
                                                 break;
@@ -128,21 +117,11 @@ detect_attack(u_char *buf, u_int32_t len, u_char *IV)
         }
         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))
+                        if (!CMP(c, buf + h[i] * SSH_BLOCKSIZE)) {
+                                if (check_crc(c, buf, len))
                                         return (DEATTACK_DETECTED);
                                 else
                                         break;
diff --git a/deattack.h b/deattack.h
index ddccdea50..7bb6100d0 100644
--- a/deattack.h
+++ b/deattack.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: deattack.h,v 1.7 2001/06/26 17:27:23 markus Exp $     */
+/*      $OpenBSD: deattack.h,v 1.8 2006/03/22 21:27:15 djm Exp $        */
 
 /*
  * Cryptographic attack detector for ssh - Header file
@@ -26,5 +26,5 @@
 #define DEATTACK_OK             0
 #define DEATTACK_DETECTED       1
 
-int      detect_attack(u_char *, u_int32_t, u_char[8]);
+int      detect_attack(u_char *, u_int32_t);
 #endif