- djm@cvs.openbsd.org 2008/06/10 23:06:19

[auth-options.c match.c servconf.c addrmatch.c sshd.8] support CIDR address matching in .ssh/authorized_keys from="..." stanzas ok and extensive testing dtucker@
2008-06-11 09:34:46 +10:00 · 2008-06-11 09:34:46 +10:00 · 896ad5a4e4
parent 8901fa9c88
commit 896ad5a4e4
6 changed files with 56 additions and 33 deletions
--- a/6
+++ b/6
@ -51,6 +51,10 @@
     requests? It could have been attacked with something like SSH'jack:
     http://www.storm.net.nz/projects/7
     feedback & ok markus
+   - djm@cvs.openbsd.org 2008/06/10 23:06:19
+     [auth-options.c match.c servconf.c addrmatch.c sshd.8]
+     support CIDR address matching in .ssh/authorized_keys from="..." stanzas
+     ok and extensive testing dtucker@
 - (dtucker) [openbsd-compat/fake-rfc2553.h] Add sin6_scope_id to sockaddr_in6
   since the new CIDR code in addmatch.c references it.
 - (dtucker) [Makefile.in configure.ac regress/addrmatch.sh] Skip IPv6
@ -4143,4 +4147,4 @@
   OpenServer 6 and add osr5bigcrypt support so when someone migrates
   passwords between UnixWare and OpenServer they will still work. OK dtucker@

-$Id: ChangeLog,v 1.4962 2008/06/10 23:34:01 dtucker Exp $
+$Id: ChangeLog,v 1.4963 2008/06/10 23:34:46 dtucker Exp $
--- a/addrmatch.c
+++ b/addrmatch.c
@ -1,4 +1,4 @@
-/*	$OpenBSD: addrmatch.c,v 1.2 2008/06/10 05:22:45 djm Exp $ */
+/*	$OpenBSD: addrmatch.c,v 1.3 2008/06/10 23:06:19 djm Exp $ */

 /*
 * Copyright (c) 2004-2008 Damien Miller <djm@mindrot.org>
@ -366,7 +366,8 @@ addr_netmatch(const struct xaddr *host, const struct xaddr *net, u_int masklen)
 *
 * Returns 1 on match found (never returned when addr == NULL).
 * Returns 0 on if no match found, or no errors found when addr == NULL.
- * Returns -1 on invalid list entry.
+ * Returns -1 on negated match found (never returned when addr == NULL).
+ * Returns -2 on invalid list entry.
 */
 int
 addr_match_list(const char *addr, const char *_list)
@ -387,7 +388,7 @@ addr_match_list(const char *addr, const char *_list)
 		if (neg)
 			cp++;
 		if (*cp == '\0') {
-			ret = -1;
+			ret = -2;
 			break;
 		}
 		/* Prefer CIDR address matching */
@ -395,14 +396,14 @@ addr_match_list(const char *addr, const char *_list)
 		if (r == -2) {
 			error("Inconsistent mask length for "
 			    "network \"%.100s\"", cp);
-			ret = -1;
+			ret = -2;
 			break;
 		} else if (r == 0) {
 			if (addr != NULL && addr_netmatch(&try_addr,
                           &match_addr, masklen) == 0) {
 foundit:
 				if (neg) {
-					ret = 0;
+					ret = -1;
 					break;
 				}
 				ret = 1;
--- a/auth-options.c
+++ b/auth-options.c
@ -1,4 +1,4 @@
-/* $OpenBSD: auth-options.c,v 1.42 2008/05/08 12:02:23 djm Exp $ */
+/* $OpenBSD: auth-options.c,v 1.43 2008/06/10 23:06:19 djm Exp $ */
 /*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@ -226,8 +226,19 @@ auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
 			}
 			patterns[i] = '\0';
 			opts++;
-			if (match_host_and_ip(remote_host, remote_ip,
-			    patterns) != 1) {
+			switch (match_host_and_ip(remote_host, remote_ip,
+			    patterns)) {
+			case 1:
+				xfree(patterns);
+				/* Host name matches. */
+				goto next_option;
+			case -1:
+				debug("%.100s, line %lu: invalid criteria",
+				    file, linenum);
+				auth_debug_add("%.100s, line %lu: "
+				    "invalid criteria", file, linenum);
+				/* FALLTHROUGH */
+			case 0:
 				xfree(patterns);
 				logit("Authentication tried for %.100s with "
 				    "correct key but not from a permitted "
@ -236,12 +247,10 @@ auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
 				auth_debug_add("Your host '%.200s' is not "
 				    "permitted to use this key for login.",
 				    remote_host);
-				/* deny access */
-				return 0;
+				break;
 			}
-			xfree(patterns);
-			/* Host name matches. */
-			goto next_option;
+			/* deny access */
+			return 0;
 		}
 		cp = "permitopen=\"";
 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
--- a/match.c
+++ b/match.c
@ -1,4 +1,4 @@
-/* $OpenBSD: match.c,v 1.26 2006/08/03 03:34:42 deraadt Exp $ */
+/* $OpenBSD: match.c,v 1.27 2008/06/10 23:06:19 djm Exp $ */
 /*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@ -183,7 +183,8 @@ match_hostname(const char *host, const char *pattern, u_int len)

 /*
 * returns 0 if we get a negative match for the hostname or the ip
- * or if we get no match at all.  returns 1 otherwise.
+ * or if we get no match at all.  returns -1 on error, or 1 on
+ * successful match.
 */
 int
 match_host_and_ip(const char *host, const char *ipaddr,
@ -191,9 +192,12 @@ match_host_and_ip(const char *host, const char *ipaddr,
 {
 	int mhost, mip;

-	/* negative ipaddr match */
-	if ((mip = match_hostname(ipaddr, patterns, strlen(patterns))) == -1)
+	/* error in ipaddr match */
+	if ((mip = addr_match_list(ipaddr, patterns)) == -2)
+		return -1;
+	else if (mip == -1) /* negative ip address match */
 		return 0;
+
 	/* negative hostname match */
 	if ((mhost = match_hostname(host, patterns, strlen(patterns))) == -1)
 		return 0;
--- a/servconf.c
+++ b/servconf.c
@ -1,4 +1,4 @@
-/* $OpenBSD: servconf.c,v 1.182 2008/06/10 04:50:25 dtucker Exp $ */
+/* $OpenBSD: servconf.c,v 1.183 2008/06/10 23:06:19 djm Exp $ */
 /*
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
@ -621,9 +621,10 @@ match_cfg_line(char **condition, int line, const char *user, const char *host,
 				    "%.100s' at line %d", address, arg, line);
 				break;
 			case 0:
+			case -1:
 				result = 0;
 				break;
-			case -1:
+			case -2:
 				return -1;
 			}
 		} else {
--- a/sshd.8
+++ b/sshd.8
@ -34,7 +34,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: sshd.8,v 1.243 2008/06/10 08:17:40 jmc Exp $
+.\" $OpenBSD: sshd.8,v 1.244 2008/06/10 23:06:19 djm Exp $
 .Dd $Mdocdate: June 10 2008 $
 .Dt SSHD 8
 .Os
@ -531,23 +531,27 @@ This option is automatically disabled if
 .Cm UseLogin
 is enabled.
 .It Cm from="pattern-list"
-Specifies that in addition to public key authentication, the canonical name
-of the remote host must be present in the comma-separated list of
-patterns.
-The purpose
-of this option is to optionally increase security: public key authentication
-by itself does not trust the network or name servers or anything (but
-the key); however, if somebody somehow steals the key, the key
-permits an intruder to log in from anywhere in the world.
-This additional option makes using a stolen key more difficult (name
-servers and/or routers would have to be compromised in addition to
-just the key).
-.Pp
+Specifies that in addition to public key authentication, either the canonical
+name of the remote host or its IP address must be present in the 
+comma-separated list of patterns.
 See
 .Sx PATTERNS
 in
 .Xr ssh_config 5
 for more information on patterns.
+.Pp
+In addition to the wildcard matching that may be applied to hostnames or
+addresses, a
+.Cm from
+stanza may match IP addressess using CIDR address/masklen notation.
+.Pp
+The purpose of this option is to optionally increase security: public key
+authentication by itself does not trust the network or name servers or
+anything (but the key); however, if somebody somehow steals the key, the key
+permits an intruder to log in from anywhere in the world.
+This additional option makes using a stolen key more difficult (name
+servers and/or routers would have to be compromised in addition to
+just the key).
 .It Cm no-agent-forwarding
 Forbids authentication agent forwarding when this key is used for
 authentication.