- OpenBSD CVS Sync

   - djm@cvs.openbsd.org 2010/02/26 20:29:54
     [PROTOCOL PROTOCOL.agent PROTOCOL.certkeys addrmatch.c auth-options.c]
     [auth-options.h auth.h auth2-pubkey.c authfd.c dns.c dns.h hostfile.c]
     [hostfile.h kex.h kexdhs.c kexgexs.c key.c key.h match.h monitor.c]
     [myproposal.h servconf.c servconf.h ssh-add.c ssh-agent.c ssh-dss.c]
     [ssh-keygen.1 ssh-keygen.c ssh-rsa.c ssh.1 ssh.c ssh2.h sshconnect.c]
     [sshconnect2.c sshd.8 sshd.c sshd_config.5]
     Add support for certificate key types for users and hosts.

     OpenSSH certificate key types are not X.509 certificates, but a much
     simpler format that encodes a public key, identity information and
     some validity constraints and signs it with a CA key. CA keys are
     regular SSH keys. This certificate style avoids the attack surface
     of X.509 certificates and is very easy to deploy.

     Certified host keys allow automatic acceptance of new host keys
     when a CA certificate is marked as sh/known_hosts.
     see VERIFYING HOST KEYS in ssh(1) for details.

     Certified user keys allow authentication of users when the signing
     CA key is marked as trusted in authorized_keys. See "AUTHORIZED_KEYS
     FILE FORMAT" in sshd(8) for details.

     Certificates are minted using ssh-keygen(1), documentation is in
     the "CERTIFICATES" section of that manpage.

     Documentation on the format of certificates is in the file
     PROTOCOL.certkeys

     feedback and ok markus@

1 files changed, 33 insertions, 4 deletions

diff --git a/auth2-pubkey.c b/auth2-pubkey.c
index 2886f1275..66ca5266b 100644
--- a/auth2-pubkey.c
+++ b/auth2-pubkey.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-pubkey.c,v 1.19 2008/07/03 21:46:58 otto Exp $ */
+/* $OpenBSD: auth2-pubkey.c,v 1.20 2010/02/26 20:29:54 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -32,6 +32,8 @@
 #include <pwd.h>
 #include <stdio.h>
 #include <stdarg.h>
+#include <string.h>
+#include <time.h>
 #include <unistd.h>
 
 #include "xmalloc.h"
@@ -178,6 +180,7 @@ static int
 user_key_allowed2(struct passwd *pw, Key *key, char *file)
 {
         char line[SSH_MAX_PUBKEY_BYTES];
+        const char *reason;
         int found_key = 0;
         FILE *f;
         u_long linenum = 0;
@@ -196,11 +199,13 @@ user_key_allowed2(struct passwd *pw, Key *key, char *file)
         }
 
         found_key = 0;
-        found = key_new(key->type);
+        found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
 
         while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
                 char *cp, *key_options = NULL;
 
+                auth_clear_options();
+
                 /* Skip leading whitespace, empty and comment lines. */
                 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
                         ;
@@ -227,8 +232,32 @@ user_key_allowed2(struct passwd *pw, Key *key, char *file)
                                 continue;
                         }
                 }
-                if (key_equal(found, key) &&
-                    auth_parse_options(pw, key_options, file, linenum) == 1) {
+                if (auth_parse_options(pw, key_options, file, linenum) != 1)
+                        continue;
+                if (key->type == KEY_RSA_CERT || key->type == KEY_DSA_CERT) {
+                        if (!key_is_cert_authority)
+                                continue;
+                        if (!key_equal(found, key->cert->signature_key))
+                                continue;
+                        debug("matching CA found: file %s, line %lu",
+                            file, linenum);
+                        fp = key_fingerprint(found, SSH_FP_MD5,
+                            SSH_FP_HEX);
+                        verbose("Found matching %s CA: %s",
+                            key_type(found), fp);
+                        xfree(fp);
+                        if (key_cert_check_authority(key, 0, 0, pw->pw_name,
+                            &reason) != 0) {
+                                error("%s", reason);
+                                auth_debug_add("%s", reason);
+                                continue;
+                        }
+                        if (auth_cert_constraints(&key->cert->constraints,
+                            pw) != 0)
+                                continue;
+                        found_key = 1;
+                        break;
+                } else if (!key_is_cert_authority && key_equal(found, key)) {
                         found_key = 1;
                         debug("matching key found: file %s, line %lu",
                             file, linenum);