Apply by doing:
cd /usr/src
patch -p0 < 015_ssh.patch
And then rebuild and install ssh:
cd usr.bin/ssh
make obj
make cleandir
make
make install
Index: usr.bin/ssh/auth.h
===================================================================
RCS file: /cvs/src/usr.bin/ssh/auth.h,v
retrieving revision 1.51
diff -u -p -r1.51 auth.h
--- usr.bin/ssh/auth.h 6 Jun 2005 11:20:36 -0000 1.51
+++ usr.bin/ssh/auth.h 10 Oct 2006 00:44:23 -0000
@@ -48,6 +48,7 @@ typedef struct KbdintDevice KbdintDevice
struct Authctxt {
int success;
+ int authenticated; /* authenticated and alarms cancelled */
int postponed; /* authentication needs another step */
int valid; /* user exists and is allowed to login */
int attempt;
Index: usr.bin/ssh/deattack.c
===================================================================
RCS file: /cvs/src/usr.bin/ssh/deattack.c,v
retrieving revision 1.20
diff -u -p -r1.20 deattack.c
--- usr.bin/ssh/deattack.c 7 Feb 2006 03:59:20 -0000 1.20
+++ usr.bin/ssh/deattack.c 10 Oct 2006 00:44:23 -0000
@@ -26,6 +26,24 @@ RCSID("$OpenBSD: deattack.c,v 1.20 2006/
#include "getput.h"
#include "xmalloc.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)
@@ -86,7 +104,7 @@ 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;
u_int32_t i, j;
- u_int32_t l;
+ u_int32_t l, same;
u_char *c;
u_char *d;
@@ -132,7 +150,7 @@ detect_attack(u_char *buf, u_int32_t len
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 (h[i] == HASH_IV) {
@@ -143,6 +161,8 @@ detect_attack(u_char *buf, u_int32_t len
break;
}
} else if (!CMP(c, buf + h[i] * SSH_BLOCKSIZE)) {
+ if (++same > MAX_IDENTICAL)
+ return (DEATTACK_DOS_DETECTED);
if (check_crc(c, buf, len, IV))
return (DEATTACK_DETECTED);
else
Index: usr.bin/ssh/deattack.h
===================================================================
RCS file: /cvs/src/usr.bin/ssh/deattack.h,v
retrieving revision 1.7
diff -u -p -r1.7 deattack.h
--- usr.bin/ssh/deattack.h 26 Jun 2001 17:27:23 -0000 1.7
+++ usr.bin/ssh/deattack.h 10 Oct 2006 00:44:23 -0000
@@ -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, u_char[8]);
#endif
Index: usr.bin/ssh/log.c
===================================================================
RCS file: /cvs/src/usr.bin/ssh/log.c,v
retrieving revision 1.29
diff -u -p -r1.29 log.c
--- usr.bin/ssh/log.c 23 Sep 2003 20:17:11 -0000 1.29
+++ usr.bin/ssh/log.c 10 Oct 2006 00:44:23 -0000
@@ -122,6 +122,18 @@ error(const char *fmt,...)
va_end(args);
}
+void
+sigdie(const char *fmt,...)
+{
+ va_list args;
+
+ va_start(args, fmt);
+ do_log(SYSLOG_LEVEL_FATAL, fmt, args);
+ va_end(args);
+ _exit(1);
+}
+
+
/* Log this message (information that usually should go to the log). */
void
Index: usr.bin/ssh/log.h
===================================================================
RCS file: /cvs/src/usr.bin/ssh/log.h,v
retrieving revision 1.11
diff -u -p -r1.11 log.h
--- usr.bin/ssh/log.h 21 Jun 2004 22:02:58 -0000 1.11
+++ usr.bin/ssh/log.h 10 Oct 2006 00:44:23 -0000
@@ -50,6 +50,7 @@ LogLevel log_level_number(char *);
void fatal(const char *, ...) __dead __attribute__((format(printf, 1, 2)));
void error(const char *, ...) __attribute__((format(printf, 1, 2)));
+void sigdie(const char *, ...) __attribute__((format(printf, 1, 2)));
void logit(const char *, ...) __attribute__((format(printf, 1, 2)));
void verbose(const char *, ...) __attribute__((format(printf, 1, 2)));
void debug(const char *, ...) __attribute__((format(printf, 1, 2)));
Index: usr.bin/ssh/packet.c
===================================================================
RCS file: /cvs/src/usr.bin/ssh/packet.c,v
retrieving revision 1.121
diff -u -p -r1.121 packet.c
--- usr.bin/ssh/packet.c 8 Feb 2006 14:38:18 -0000 1.121
+++ usr.bin/ssh/packet.c 10 Oct 2006 00:44:24 -0000
@@ -976,9 +976,16 @@ packet_read_poll1(void)
* (C)1998 CORE-SDI, Buenos Aires Argentina
* Ariel Futoransky(
[email protected])
*/
- 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);
Index: usr.bin/ssh/session.c
===================================================================
RCS file: /cvs/src/usr.bin/ssh/session.c,v
retrieving revision 1.197
diff -u -p -r1.197 session.c
--- usr.bin/ssh/session.c 28 Feb 2006 01:10:21 -0000 1.197
+++ usr.bin/ssh/session.c 10 Oct 2006 00:44:24 -0000
@@ -2052,7 +2052,7 @@ do_cleanup(Authctxt *authctxt)
return;
called = 1;
- if (authctxt == NULL)
+ if (authctxt == NULL || !authctxt->authenticated)
return;
#ifdef KRB5
if (options.kerberos_ticket_cleanup &&
Index: usr.bin/ssh/sshd.c
===================================================================
RCS file: /cvs/src/usr.bin/ssh/sshd.c,v
retrieving revision 1.323
diff -u -p -r1.323 sshd.c
--- usr.bin/ssh/sshd.c 20 Feb 2006 17:19:54 -0000 1.323
+++ usr.bin/ssh/sshd.c 10 Oct 2006 00:44:25 -0000
@@ -309,13 +309,11 @@ main_sigchld_handler(int sig)
static void
grace_alarm_handler(int sig)
{
- /* XXX no idea how fix this signal handler */
-
if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
kill(pmonitor->m_pid, SIGALRM);
/* Log error and exit. */
- fatal("Timeout before authentication for %s", get_remote_ipaddr());
+ sigdie("Timeout before authentication for %s", get_remote_ipaddr());
}
/*
@@ -1654,6 +1652,7 @@ main(int ac, char **av)
*/
alarm(0);
signal(SIGALRM, SIG_DFL);
+ authctxt->authenticated = 1;
if (startup_pipe != -1) {
close(startup_pipe);
startup_pipe = -1;