From 1aed65eb27feec505997c98621bdf158f9ab8b99 Mon Sep 17 00:00:00 2001
From: Damien Miller <djm@mindrot.org>
Date: Thu, 4 Mar 2010 21:53:35 +1100
Subject:    - djm@cvs.openbsd.org 2010/03/04 10:36:03      [auth-rh-rsa.c
 auth-rsa.c auth.c auth.h auth2-hostbased.c auth2-pubkey.c]      [authfile.c
 authfile.h hostfile.c hostfile.h servconf.c servconf.h]      [ssh-keygen.c
 ssh.1 sshconnect.c sshd_config.5]      Add a TrustedUserCAKeys option to
 sshd_config to specify CA keys that      are trusted to authenticate users
 (in addition than doing it per-user      in authorized_keys).

     Add a RevokedKeys option to sshd_config and a @revoked marker to
     known_hosts to allow keys to me revoked and banned for user or host
     authentication.

     feedback and ok markus@
---
 auth2-pubkey.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 52 insertions(+), 1 deletion(-)

(limited to 'auth2-pubkey.c')

diff --git a/auth2-pubkey.c b/auth2-pubkey.c
index 66ca5266..51aa7748 100644
--- a/auth2-pubkey.c
+++ b/auth2-pubkey.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-pubkey.c,v 1.20 2010/02/26 20:29:54 djm Exp $ */
+/* $OpenBSD: auth2-pubkey.c,v 1.21 2010/03/04 10:36:03 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -56,6 +56,7 @@
 #endif
 #include "monitor_wrap.h"
 #include "misc.h"
+#include "authfile.h"
 
 /* import */
 extern ServerOptions options;
@@ -276,6 +277,47 @@ user_key_allowed2(struct passwd *pw, Key *key, char *file)
 	return found_key;
 }
 
+/* Authenticate a certificate key against TrustedUserCAKeys */
+static int
+user_cert_trusted_ca(struct passwd *pw, Key *key)
+{
+	char *key_fp, *ca_fp;
+	const char *reason;
+	int ret = 0;
+
+	if (!key_is_cert(key) || options.trusted_user_ca_keys == NULL)
+		return 0;
+
+	key_fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
+	ca_fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
+
+	if (key_in_file(key->cert->signature_key,
+	    options.trusted_user_ca_keys, 1) != 1) {
+		debug2("%s: CA %s %s is not listed in %s", __func__,
+		    key_type(key->cert->signature_key), ca_fp,
+		    options.trusted_user_ca_keys);
+		goto out;
+	}
+	if (key_cert_check_authority(key, 0, 1, pw->pw_name, &reason) != 0) {
+		error("%s", reason);
+		auth_debug_add("%s", reason);
+		goto out;
+	}
+	if (auth_cert_constraints(&key->cert->constraints, pw) != 0)
+		goto out;
+
+	verbose("%s certificate %s allowed by trusted %s key %s",
+	    key_type(key), key_fp, key_type(key->cert->signature_key), ca_fp);
+	ret = 1;
+
+ out:
+	if (key_fp != NULL)
+		xfree(key_fp);
+	if (ca_fp != NULL)
+		xfree(ca_fp);
+	return ret;
+}
+
 /* check whether given key is in .ssh/authorized_keys* */
 int
 user_key_allowed(struct passwd *pw, Key *key)
@@ -283,6 +325,15 @@ user_key_allowed(struct passwd *pw, Key *key)
 	int success;
 	char *file;
 
+	if (auth_key_is_revoked(key))
+		return 0;
+	if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key))
+		return 0;
+
+	success = user_cert_trusted_ca(pw, key);
+	if (success)
+		return success;
+
 	file = authorized_keys_file(pw);
 	success = user_key_allowed2(pw, key, file);
 	xfree(file);
-- 
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