1 files changed, 43 insertions, 38 deletions

diff --git a/deattack.c b/deattack.c
index 1b37e4dab..e76481a6d 100644
--- a/deattack.c
+++ b/deattack.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: deattack.c,v 1.30 2006/09/16 19:53:37 djm Exp $ */
+/* $OpenBSD: deattack.c,v 1.32 2015/01/20 23:14:00 deraadt Exp $ */
 /*
  * Cryptographic attack detector for ssh - source code
  *
@@ -20,16 +20,13 @@
 
 #include "includes.h"
 
-#include <sys/types.h>
-
 #include <string.h>
 #include <stdio.h>
-#include <stdarg.h>
+#include <stdlib.h>
 
-#include "xmalloc.h"
 #include "deattack.h"
-#include "log.h"
 #include "crc32.h"
+#include "sshbuf.h"
 #include "misc.h"
 
 /*
@@ -66,7 +63,7 @@
 
 
 /* Hash function (Input keys are cipher results) */
-#define HASH(x)         get_u32(x)
+#define HASH(x)         PEEK_U32(x)
 
 #define CMP(a, b)       (memcmp(a, b, SSH_BLOCKSIZE))
 
@@ -79,10 +76,10 @@ crc_update(u_int32_t *a, u_int32_t 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)
+check_crc(const u_char *S, const u_char *buf, u_int32_t len)
 {
         u_int32_t crc;
-        u_char *c;
+        const u_char *c;
 
         crc = 0;
         for (c = buf; c < buf + len; c += SSH_BLOCKSIZE) {
@@ -94,36 +91,44 @@ check_crc(u_char *S, u_char *buf, u_int32_t len)
                         crc_update(&crc, 0);
                 }
         }
-        return (crc == 0);
+        return crc == 0;
 }
 
+void
+deattack_init(struct deattack_ctx *dctx)
+{
+        bzero(dctx, sizeof(*dctx));
+        dctx->n = HASH_MINSIZE / HASH_ENTRYSIZE;
+}
 
 /* Detect a crc32 compensation attack on a packet */
 int
-detect_attack(u_char *buf, u_int32_t len)
+detect_attack(struct deattack_ctx *dctx, const 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;
-        u_int32_t i, j;
-        u_int32_t l, same;
-        u_char *c;
-        u_char *d;
+        u_int32_t i, j, l, same;
+        u_int16_t *tmp;
+        const u_char *c, *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)
+            len % SSH_BLOCKSIZE != 0)
+                return DEATTACK_ERROR;
+        for (l = dctx->n; l < HASH_FACTOR(len / SSH_BLOCKSIZE); l = l << 2)
                 ;
 
-        if (h == NULL) {
-                debug("Installing crc compensation attack detector.");
-                h = (u_int16_t *) xcalloc(l, HASH_ENTRYSIZE);
-                n = l;
+        if (dctx->h == NULL) {
+                if ((dctx->h = calloc(l, HASH_ENTRYSIZE)) == NULL)
+                        return DEATTACK_ERROR;
+                dctx->n = l;
         } else {
-                if (l > n) {
-                        h = (u_int16_t *)xrealloc(h, l, HASH_ENTRYSIZE);
-                        n = l;
+                if (l > dctx->n) {
+                        if ((tmp = reallocarray(dctx->h, l, HASH_ENTRYSIZE))
+                            == NULL) {
+                                free(dctx->h);
+                                dctx->h = NULL;
+                                return DEATTACK_ERROR;
+                        }
+                        dctx->h = tmp;
+                        dctx->n = l;
                 }
         }
 
@@ -132,29 +137,29 @@ detect_attack(u_char *buf, u_int32_t len)
                         for (d = buf; d < c; d += SSH_BLOCKSIZE) {
                                 if (!CMP(c, d)) {
                                         if ((check_crc(c, buf, len)))
-                                                return (DEATTACK_DETECTED);
+                                                return DEATTACK_DETECTED;
                                         else
                                                 break;
                                 }
                         }
                 }
-                return (DEATTACK_OK);
+                return DEATTACK_OK;
         }
-        memset(h, HASH_UNUSEDCHAR, n * HASH_ENTRYSIZE);
+        memset(dctx->h, HASH_UNUSEDCHAR, dctx->n * HASH_ENTRYSIZE);
 
         for (c = buf, same = 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 (!CMP(c, buf + h[i] * SSH_BLOCKSIZE)) {
+                for (i = HASH(c) & (dctx->n - 1); dctx->h[i] != HASH_UNUSED;
+                    i = (i + 1) & (dctx->n - 1)) {
+                        if (!CMP(c, buf + dctx->h[i] * SSH_BLOCKSIZE)) {
                                 if (++same > MAX_IDENTICAL)
-                                        return (DEATTACK_DOS_DETECTED);
+                                        return DEATTACK_DOS_DETECTED;
                                 if (check_crc(c, buf, len))
-                                        return (DEATTACK_DETECTED);
+                                        return DEATTACK_DETECTED;
                                 else
                                         break;
                         }
                 }
-                h[i] = j;
+                dctx->h[i] = j;
         }
-        return (DEATTACK_OK);
+        return DEATTACK_OK;
 }