SOURCES: openssh-identical-simple-dos-2.patch (NEW) - CVE-2006-492...

[glen]

Author: glen                         Date: Wed Sep 27 19:40:48 2006 GMT
Module: SOURCES                       Tag: HEAD
---- Log message:
- CVE-2006-4924 from gentoo

---- Files affected:
SOURCES:
   openssh-identical-simple-dos-2.patch (NONE -> 1.1)  (NEW)

---- Diffs:

================================================================
Index: SOURCES/openssh-identical-simple-dos-2.patch
diff -u /dev/null SOURCES/openssh-identical-simple-dos-2.patch:1.1
--- /dev/null	Wed Sep 27 21:40:48 2006
+++ SOURCES/openssh-identical-simple-dos-2.patch	Wed Sep 27 21:40:43 2006
@@ -0,0 +1,119 @@
+http://bugs.gentoo.org/148228
+
+taken from upstream cvs and munged a little to apply against 4.3p2
+
+===================================================================
+RCS file: /usr/OpenBSD/cvs/src/usr.bin/ssh/deattack.c,v
+retrieving revision 1.29
+retrieving revision 1.30
+diff -u -r1.29 -r1.30
+--- src/usr.bin/ssh/deattack.c	2006/08/03 03:34:42	1.29
++++ src/usr.bin/ssh/deattack.c	2006/09/16 19:53:37	1.30
+@@ -30,6 +30,24 @@
+ #include "crc32.h"
+ #include "misc.h"
+ 
++/*
++ * CRC attack detection has a worst-case behaviour that is O(N^3) over
++ * the number of identical blocks in a packet. This behaviour can be 
++ * exploited to create a limited denial of service attack. 
++ * 
++ * However, because we are dealing with encrypted data, identical
++ * blocks should only occur every 2^35 maximally-sized packets or so. 
++ * Consequently, we can detect this DoS by looking for identical blocks
++ * in a packet.
++ *
++ * The parameter below determines how many identical blocks we will
++ * accept in a single packet, trading off between attack detection and
++ * likelihood of terminating a legitimate connection. A value of 32 
++ * corresponds to an average of 2^40 messages before an attack is
++ * misdetected
++ */
++#define MAX_IDENTICAL	32
++
+ /* SSH Constants */
+ #define SSH_MAXBLOCKS	(32 * 1024)
+ #define SSH_BLOCKSIZE	(8)
+@@ -85,7 +103,7 @@
+ 	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;
++	u_int32_t l, same;
+ 	u_char *c;
+ 	u_char *d;
+ 
+@@ -122,11 +140,13 @@
+ 	if (IV)
+ 		h[HASH(IV) & (n - 1)] = HASH_IV;
+ 
+-	for (c = buf, j = 0; c < (buf + len); c += SSH_BLOCKSIZE, j++) {
++	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) && ++same > MAX_IDENTICAL)
++                return (DEATTACK_DOS_DETECTED);
+ 			if (h[i] == HASH_IV) {
+ 				if (!CMP(c, IV)) {
+ 					if (check_crc(c, buf, len, IV))
+ 						return (DEATTACK_DETECTED);
+ 					else
+===================================================================
+RCS file: /usr/OpenBSD/cvs/src/usr.bin/ssh/packet.c,v
+retrieving revision 1.143
+retrieving revision 1.144
+diff -u -r1.143 -r1.144
+--- src/usr.bin/ssh/packet.c	2006/08/05 08:34:04	1.143
++++ src/usr.bin/ssh/packet.c	2006/09/16 19:53:37	1.144
+@@ -991,9 +991,16 @@
+ 	 * (C)1998 CORE-SDI, Buenos Aires Argentina
+ 	 * Ariel Futoransky(futo at core-sdi.com)
+ 	 */
+-	if (!receive_context.plaintext &&
+-	    detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED)
+-		packet_disconnect("crc32 compensation attack: network attack detected");
++	if (!receive_context.plaintext) {
++		switch (detect_attack(buffer_ptr(&input), padded_len, NULL)) {
++		case DEATTACK_DETECTED:
++			packet_disconnect("crc32 compensation attack: "
++			    "network attack detected");
++		case DEATTACK_DOS_DETECTED:
++			packet_disconnect("deattack denial of "
++			    "service detected");
++		}
++	}
+ 
+ 	/* Decrypt data to incoming_packet. */
+ 	buffer_clear(&incoming_packet);
+===================================================================
+RCS file: /usr/OpenBSD/cvs/src/usr.bin/ssh/deattack.h,v
+retrieving revision 1.9
+retrieving revision 1.10
+diff -u -r1.9 -r1.10
+--- src/usr.bin/ssh/deattack.h	2006/03/25 22:22:43	1.9
++++ src/usr.bin/ssh/deattack.h	2006/09/16 19:53:37	1.10
+@@ -25,6 +25,7 @@
+ /* Return codes */
+ #define DEATTACK_OK		0
+ #define DEATTACK_DETECTED	1
++#define DEATTACK_DOS_DETECTED	2
+ 
+ int	 detect_attack(u_char *, u_int32_t);
+ #endif
+===================================================================
+RCS file: /usr/OpenBSD/cvs/src/usr.bin/ssh/packet.c,v
+retrieving revision 1.144
+retrieving revision 1.145
+diff -u -r1.144 -r1.145
+--- src/usr.bin/ssh/packet.c	2006/09/16 19:53:37	1.144
++++ src/usr.bin/ssh/packet.c	2006/09/19 21:14:08	1.145
+@@ -682,6 +682,9 @@
+ 	 */
+ 	after_authentication = 1;
+ 	for (mode = 0; mode < MODE_MAX; mode++) {
++		/* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
++		if (newkeys[mode] == NULL)
++			continue;
+ 		comp = &newkeys[mode]->comp;
+ 		if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
+ 			packet_init_compression();
================================================================