===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/sshconnect.c,v
retrieving revision 1.218
retrieving revision 1.219
diff -u -r1.218 -r1.219
--- src/usr.bin/ssh/sshconnect.c	2010/01/13 00:19:04	1.218
+++ src/usr.bin/ssh/sshconnect.c	2010/02/26 20:29:54	1.219
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect.c,v 1.218 2010/01/13 00:19:04 dtucker Exp $ */
+/* $OpenBSD: sshconnect.c,v 1.219 2010/02/26 20:29:54 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -49,6 +49,7 @@
 #include "misc.h"
 #include "dns.h"
 #include "roaming.h"
+#include "ssh2.h"
 #include "version.h"
 
 char *client_version_string = NULL;
@@ -567,6 +568,23 @@
 	}
 }
 
+static int
+check_host_cert(const char *host, const Key *host_key)
+{
+	const char *reason;
+
+	if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
+		error("%s", reason);
+		return 0;
+	}
+	if (buffer_len(&host_key->cert->constraints) != 0) {
+		error("Certificate for %s contains unsupported constraint(s)",
+		    host);
+		return 0;
+	}
+	return 1;
+}
+
 /*
  * check whether the supplied host key is valid, return -1 if the key
  * is not valid. the user_hostfile will not be updated if 'readonly' is true.
@@ -579,13 +597,13 @@
     Key *host_key, int readonly, const char *user_hostfile,
     const char *system_hostfile)
 {
-	Key *file_key;
-	const char *type = key_type(host_key);
+	Key *file_key, *raw_key = NULL;
+	const char *type;
 	char *ip = NULL, *host = NULL;
 	char hostline[1000], *hostp, *fp, *ra;
 	HostStatus host_status;
 	HostStatus ip_status;
-	int r, local = 0, host_ip_differ = 0;
+	int r, want_cert, local = 0, host_ip_differ = 0;
 	char ntop[NI_MAXHOST];
 	char msg[1024];
 	int len, host_line, ip_line, cancelled_forwarding = 0;
@@ -654,11 +672,15 @@
 		host = put_host_port(hostname, port);
 	}
 
+ retry:
+	want_cert = key_is_cert(host_key);
+	type = key_type(host_key);
+
 	/*
 	 * Store the host key from the known host file in here so that we can
 	 * compare it with the key for the IP address.
 	 */
-	file_key = key_new(host_key->type);
+	file_key = key_new(key_is_cert(host_key) ? KEY_UNSPEC : host_key->type);
 
 	/*
 	 * Check if the host key is present in the user's list of known
@@ -674,9 +696,10 @@
 	}
 	/*
 	 * Also perform check for the ip address, skip the check if we are
-	 * localhost or the hostname was an ip address to begin with
+	 * localhost, looking for a certificate, or the hostname was an ip
+	 * address to begin with.
 	 */
-	if (options.check_host_ip) {
+	if (!want_cert && options.check_host_ip) {
 		Key *ip_key = key_new(host_key->type);
 
 		ip_file = user_hostfile;
@@ -700,11 +723,14 @@
 	switch (host_status) {
 	case HOST_OK:
 		/* The host is known and the key matches. */
-		debug("Host '%.200s' is known and matches the %s host key.",
-		    host, type);
-		debug("Found key in %s:%d", host_file, host_line);
+		debug("Host '%.200s' is known and matches the %s host %s.",
+		    host, type, want_cert ? "certificate" : "key");
+		debug("Found %s in %s:%d",
+		    want_cert ? "certificate" : "key", host_file, host_line);
+		if (want_cert && !check_host_cert(hostname, host_key))
+			goto fail;
 		if (options.check_host_ip && ip_status == HOST_NEW) {
-			if (readonly)
+			if (readonly || want_cert)
 				logit("%s host key for IP address "
 				    "'%.128s' not in list of known hosts.",
 				    type, ip);
@@ -736,7 +762,7 @@
 				break;
 			}
 		}
-		if (readonly)
+		if (readonly || want_cert)
 			goto fail;
 		/* The host is new. */
 		if (options.strict_host_key_checking == 1) {
@@ -821,6 +847,17 @@
 			    "list of known hosts.", hostp, type);
 		break;
 	case HOST_CHANGED:
+		if (want_cert) {
+			/*
+			 * This is only a debug() since it is valid to have
+			 * CAs with wildcard DNS matches that don't match
+			 * all hosts that one might visit.
+			 */
+			debug("Host certificate authority does not "
+			    "match %s in %s:%d", CA_MARKER,
+			    host_file, host_line);
+			goto fail;
+		}
 		if (readonly == ROQUIET)
 			goto fail;
 		if (options.check_host_ip && host_ip_differ) {
@@ -957,6 +994,20 @@
 	return 0;
 
 fail:
+	if (want_cert) {
+		/*
+		 * No matching certificate. Downgrade cert to raw key and
+		 * search normally.
+		 */
+		debug("No matching CA found. Retry with plain key");
+		raw_key = key_from_private(host_key);
+		if (key_drop_cert(raw_key) != 0)
+			fatal("Couldn't drop certificate");
+		host_key = raw_key;
+		goto retry;
+	}
+	if (raw_key != NULL)
+		key_free(raw_key);
 	xfree(ip);
 	xfree(host);
 	return -1;
@@ -969,7 +1020,8 @@
 	struct stat st;
 	int flags = 0;
 
-	if (options.verify_host_key_dns &&
+	/* XXX certs are not yet supported for DNS */
+	if (!key_is_cert(host_key) && options.verify_host_key_dns &&
 	    verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
 
 		if (flags & DNS_VERIFY_FOUND) {