1 /* $OpenBSD: auth-rh-rsa.c,v 1.43 2010/03/04 10:36:03 djm Exp $ */
2 /*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * All rights reserved
6 * Rhosts or /etc/hosts.equiv authentication combined with RSA host
7 * authentication.
8 *
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose. Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
14 */
15
16 #include "includes.h"
17
18 #include <sys/types.h>
19
20 #include <pwd.h>
21 #include <stdarg.h>
22
23 #include "packet.h"
24 #include "uidswap.h"
25 #include "log.h"
26 #include "buffer.h"
27 #include "servconf.h"
28 #include "key.h"
29 #include "hostfile.h"
30 #include "pathnames.h"
31 #include "auth.h"
32 #include "canohost.h"
33 #ifdef GSSAPI
34 #include "ssh-gss.h"
35 #endif
36 #include "monitor_wrap.h"
37
38 /* import */
39 extern ServerOptions options;
40
41 int
auth_rhosts_rsa_key_allowed(struct passwd * pw,char * cuser,char * chost,Key * client_host_key)42 auth_rhosts_rsa_key_allowed(struct passwd *pw, char *cuser, char *chost,
43 Key *client_host_key)
44 {
45 HostStatus host_status;
46
47 if (auth_key_is_revoked(client_host_key))
48 return 0;
49
50 /* Check if we would accept it using rhosts authentication. */
51 if (!auth_rhosts(pw, cuser))
52 return 0;
53
54 host_status = check_key_in_hostfiles(pw, client_host_key,
55 chost, _PATH_SSH_SYSTEM_HOSTFILE,
56 options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
57
58 return (host_status == HOST_OK);
59 }
60
61 /*
62 * Tries to authenticate the user using the .rhosts file and the host using
63 * its host key. Returns true if authentication succeeds.
64 */
65 int
auth_rhosts_rsa(Authctxt * authctxt,char * cuser,Key * client_host_key)66 auth_rhosts_rsa(Authctxt *authctxt, char *cuser, Key *client_host_key)
67 {
68 char *chost;
69 struct passwd *pw = authctxt->pw;
70
71 debug("Trying rhosts with RSA host authentication for client user %.100s",
72 cuser);
73
74 if (!authctxt->valid || client_host_key == NULL ||
75 client_host_key->rsa == NULL)
76 return 0;
77
78 chost = (char *)get_canonical_hostname(options.use_dns);
79 debug("Rhosts RSA authentication: canonical host %.900s", chost);
80
81 if (!PRIVSEP(auth_rhosts_rsa_key_allowed(pw, cuser, chost, client_host_key))) {
82 debug("Rhosts with RSA host authentication denied: unknown or invalid host key");
83 packet_send_debug("Your host key cannot be verified: unknown or invalid host key.");
84 return 0;
85 }
86 /* A matching host key was found and is known. */
87
88 /* Perform the challenge-response dialog with the client for the host key. */
89 if (!auth_rsa_challenge_dialog(client_host_key)) {
90 logit("Client on %.800s failed to respond correctly to host authentication.",
91 chost);
92 return 0;
93 }
94 /*
95 * We have authenticated the user using .rhosts or /etc/hosts.equiv,
96 * and the host using RSA. We accept the authentication.
97 */
98
99 verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.",
100 pw->pw_name, cuser, chost);
101 packet_send_debug("Rhosts with RSA host authentication accepted.");
102 return 1;
103 }
104