- djm@cvs.openbsd.org 2010/08/04 05:42:47

[auth.c auth2-hostbased.c authfile.c authfile.h ssh-keysign.8]
     [ssh-keysign.c ssh.c]
     enable certificates for hostbased authentication, from Iain Morgan;
     "looks ok" markus@

ChangeLog

@@ -9,6 +9,11 @@
      [PROTOCOL.certkeys ssh-keygen.c]
      tighten the rules for certificate encoding by requiring that options
      appear in lexical order and make our ssh-keygen comply. ok markus@
+   - djm@cvs.openbsd.org 2010/08/04 05:42:47
+     [auth.c auth2-hostbased.c authfile.c authfile.h ssh-keysign.8]
+     [ssh-keysign.c ssh.c]
+     enable certificates for hostbased authentication, from Iain Morgan;
+     "looks ok" markus@
 
 20100903
  - (dtucker) [monitor.c] Bug #1795: Initialize the values to be returned from

auth.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: auth.c,v 1.88 2010/06/22 04:49:47 djm Exp $ */
+/* $OpenBSD: auth.c,v 1.89 2010/08/04 05:42:47 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -385,7 +385,7 @@ check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
 	HostStatus host_status;
 
 	/* Check if we know the host and its host key. */
-	found = key_new(key->type);
+	found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
 	host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
 
 	if (host_status != HOST_OK && userfile != NULL) {

auth2-hostbased.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-hostbased.c,v 1.13 2010/03/04 10:36:03 djm Exp $ */
+/* $OpenBSD: auth2-hostbased.c,v 1.14 2010/08/04 05:42:47 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -141,9 +141,10 @@ int
 hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
     Key *key)
 {
-	const char *resolvedname, *ipaddr, *lookup;
+	const char *resolvedname, *ipaddr, *lookup, *reason;
 	HostStatus host_status;
 	int len;
+	char *fp;
 
 	if (auth_key_is_revoked(key))
 		return 0;
@@ -174,16 +175,40 @@ hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
 	}
 	debug2("userauth_hostbased: access allowed by auth_rhosts2");
 
+	if (key_is_cert(key) && 
+	    key_cert_check_authority(key, 1, 0, lookup, &reason)) {
+		error("%s", reason);
+		auth_debug_add("%s", reason);
+		return 0;
+	}
+
 	host_status = check_key_in_hostfiles(pw, key, lookup,
 	    _PATH_SSH_SYSTEM_HOSTFILE,
 	    options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
 
 	/* backward compat if no key has been found. */
-	if (host_status == HOST_NEW)
+	if (host_status == HOST_NEW) {
 		host_status = check_key_in_hostfiles(pw, key, lookup,
 		    _PATH_SSH_SYSTEM_HOSTFILE2,
 		    options.ignore_user_known_hosts ? NULL :
 		    _PATH_SSH_USER_HOSTFILE2);
+	}
+
+	if (host_status == HOST_OK) {
+		if (key_is_cert(key)) {
+			fp = key_fingerprint(key->cert->signature_key,
+			    SSH_FP_MD5, SSH_FP_HEX);
+			verbose("Accepted certificate ID \"%s\" signed by "
+			    "%s CA %s from %s@%s", key->cert->key_id,
+			    key_type(key->cert->signature_key), fp,
+			    cuser, lookup);
+		} else {
+			fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
+			verbose("Accepted %s public key %s from %s@%s",
+			    key_type(key), fp, cuser, lookup);
+		}
+		xfree(fp);
+	}
 
 	return (host_status == HOST_OK);
 }

authfile.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: authfile.c,v 1.80 2010/03/04 10:36:03 djm Exp $ */
+/* $OpenBSD: authfile.c,v 1.81 2010/08/04 05:42:47 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -693,6 +693,64 @@ key_load_public(const char *filename, char **commentp)
 	return NULL;
 }
 
+/* Load the certificate associated with the named private key */
+Key *
+key_load_cert(const char *filename)
+{
+	Key *pub;
+	char file[MAXPATHLEN];
+
+	pub = key_new(KEY_UNSPEC);
+	if ((strlcpy(file, filename, sizeof file) < sizeof(file)) &&
+	    (strlcat(file, "-cert.pub", sizeof file) < sizeof(file)) &&
+	    (key_try_load_public(pub, file, NULL) == 1))
+		return pub;
+	key_free(pub);
+	return NULL;
+}
+
+/* Load private key and certificate */
+Key *
+key_load_private_cert(int type, const char *filename, const char *passphrase,
+    int *perm_ok)
+{
+	Key *key, *pub;
+
+	switch (type) {
+	case KEY_RSA:
+	case KEY_DSA:
+		break;
+	default:
+		error("%s: unsupported key type", __func__);
+		return NULL;
+	}
+
+	if ((key = key_load_private_type(type, filename, 
+	    passphrase, NULL, perm_ok)) == NULL)
+		return NULL;
+
+	if ((pub = key_load_cert(filename)) == NULL) {
+		key_free(key);
+		return NULL;
+	}
+
+	/* Make sure the private key matches the certificate */
+	if (key_equal_public(key, pub) == 0) {
+		error("%s: certificate does not match private key %s",
+		    __func__, filename);
+	} else if (key_to_certified(key, key_cert_is_legacy(pub)) != 0) {
+		error("%s: key_to_certified failed", __func__);
+	} else {
+		key_cert_copy(pub, key);
+		key_free(pub);
+		return key;
+	}
+
+	key_free(key);
+	key_free(pub);
+	return NULL;
+}
+
 /*
  * Returns 1 if the specified "key" is listed in the file "filename",
  * 0 if the key is not listed or -1 on error.

authfile.h

@@ -1,4 +1,4 @@
-/* $OpenBSD: authfile.h,v 1.14 2010/03/04 10:36:03 djm Exp $ */
+/* $OpenBSD: authfile.h,v 1.15 2010/08/04 05:42:47 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -16,9 +16,11 @@
 #define AUTHFILE_H
 
 int	 key_save_private(Key *, const char *, const char *, const char *);
+Key	*key_load_cert(const char *);
 Key	*key_load_public(const char *, char **);
 Key	*key_load_public_type(int, const char *, char **);
 Key	*key_load_private(const char *, const char *, char **);
+Key	*key_load_private_cert(int, const char *, const char *, int *);
 Key	*key_load_private_type(int, const char *, const char *, char **, int *);
 Key	*key_load_private_pem(int, int, const char *, char **);
 int	 key_perm_ok(int, const char *);

ssh-keysign.8

@@ -1,4 +1,4 @@
-.\" $OpenBSD: ssh-keysign.8,v 1.9 2007/05/31 19:20:16 jmc Exp $
+.\" $OpenBSD: ssh-keysign.8,v 1.10 2010/08/04 05:42:47 djm Exp $
 .\"
 .\" Copyright (c) 2002 Markus Friedl.  All rights reserved.
 .\"
@@ -22,7 +22,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: May 31 2007 $
+.Dd $Mdocdate: August 4 2010 $
 .Dt SSH-KEYSIGN 8
 .Os
 .Sh NAME
@@ -68,6 +68,9 @@ accessible to others.
 Since they are readable only by root,
 .Nm
 must be set-uid root if host-based authentication is used.
+.It Pa /etc/ssh/ssh_host_dsa_key-cert.pub, /etc/ssh/ssh_host_rsa_key-cert.pub
+If these files exist they are assumed to contain public certificate
+information corresponding with the private keys above.
 .El
 .Sh SEE ALSO
 .Xr ssh 1 ,

ssh-keysign.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-keysign.c,v 1.30 2010/01/13 01:20:20 dtucker Exp $ */
+/* $OpenBSD: ssh-keysign.c,v 1.31 2010/08/04 05:42:47 djm Exp $ */
 /*
  * Copyright (c) 2002 Markus Friedl.  All rights reserved.
  *
@@ -232,7 +232,7 @@ main(int argc, char **argv)
 	found = 0;
 	for (i = 0; i < 2; i++) {
 		if (keys[i] != NULL &&
-		    key_equal(key, keys[i])) {
+		    key_equal_public(key, keys[i])) {
 			found = 1;
 			break;
 		}

ssh.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.344 2010/07/19 09:15:12 djm Exp $ */
+/* $OpenBSD: ssh.c,v 1.345 2010/08/04 05:42:47 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -774,26 +774,34 @@ main(int ac, char **av)
 	sensitive_data.external_keysign = 0;
 	if (options.rhosts_rsa_authentication ||
 	    options.hostbased_authentication) {
-		sensitive_data.nkeys = 3;
+		sensitive_data.nkeys = 5;
 		sensitive_data.keys = xcalloc(sensitive_data.nkeys,
 		    sizeof(Key));
 
 		PRIV_START;
 		sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 		    _PATH_HOST_KEY_FILE, "", NULL, NULL);
-		sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
+		sensitive_data.keys[1] = key_load_private_cert(KEY_DSA,
+		    _PATH_HOST_DSA_KEY_FILE, "", NULL);
+		sensitive_data.keys[2] = key_load_private_cert(KEY_RSA,
+		    _PATH_HOST_RSA_KEY_FILE, "", NULL);
+		sensitive_data.keys[3] = key_load_private_type(KEY_DSA,
 		    _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
-		sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
+		sensitive_data.keys[4] = key_load_private_type(KEY_RSA,
 		    _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
 		PRIV_END;
 
 		if (options.hostbased_authentication == 1 &&
 		    sensitive_data.keys[0] == NULL &&
-		    sensitive_data.keys[1] == NULL &&
+		    sensitive_data.keys[3] == NULL &&
-		    sensitive_data.keys[2] == NULL) {
+		    sensitive_data.keys[4] == NULL) {
-			sensitive_data.keys[1] = key_load_public(
+			sensitive_data.keys[1] = key_load_cert(
+			    _PATH_HOST_DSA_KEY_FILE);
+			sensitive_data.keys[2] = key_load_cert(
+			    _PATH_HOST_RSA_KEY_FILE);
+			sensitive_data.keys[3] = key_load_public(
 			    _PATH_HOST_DSA_KEY_FILE, NULL);
-			sensitive_data.keys[2] = key_load_public(
+			sensitive_data.keys[4] = key_load_public(
 			    _PATH_HOST_RSA_KEY_FILE, NULL);
 			sensitive_data.external_keysign = 1;
 		}