1/*	$NetBSD: auth-rh-rsa.c,v 1.3 2010/11/21 18:29:48 adam Exp $	*/
2/* $OpenBSD: auth-rh-rsa.c,v 1.43 2010/03/04 10:36:03 djm Exp $ */
3/*
4 * Author: Tatu Ylonen <ylo@cs.hut.fi>
5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 *                    All rights reserved
7 * Rhosts or /etc/hosts.equiv authentication combined with RSA host
8 * authentication.
9 *
10 * As far as I am concerned, the code I have written for this software
11 * can be used freely for any purpose.  Any derived versions of this
12 * software must be clearly marked as such, and if the derived work is
13 * incompatible with the protocol description in the RFC file, it must be
14 * called by a name other than "ssh" or "Secure Shell".
15 */
16
17#include "includes.h"
18__RCSID("$NetBSD: auth-rh-rsa.c,v 1.3 2010/11/21 18:29:48 adam Exp $");
19#include <sys/types.h>
20
21#include <pwd.h>
22#include <stdarg.h>
23
24#include "packet.h"
25#include "uidswap.h"
26#include "log.h"
27#include "buffer.h"
28#include "servconf.h"
29#include "key.h"
30#include "hostfile.h"
31#include "pathnames.h"
32#include "auth.h"
33#include "canohost.h"
34#ifdef GSSAPI
35#include "ssh-gss.h"
36#endif
37#include "monitor_wrap.h"
38
39/* import */
40extern ServerOptions options;
41
42int
43auth_rhosts_rsa_key_allowed(struct passwd *pw, char *cuser, char *chost,
44    Key *client_host_key)
45{
46	HostStatus host_status;
47
48	if (auth_key_is_revoked(client_host_key))
49		return 0;
50
51	/* Check if we would accept it using rhosts authentication. */
52	if (!auth_rhosts(pw, cuser))
53		return 0;
54
55	host_status = check_key_in_hostfiles(pw, client_host_key,
56	    chost, _PATH_SSH_SYSTEM_HOSTFILE,
57	    options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
58
59	return (host_status == HOST_OK);
60}
61
62/*
63 * Tries to authenticate the user using the .rhosts file and the host using
64 * its host key.  Returns true if authentication succeeds.
65 */
66int
67auth_rhosts_rsa(Authctxt *authctxt, char *cuser, Key *client_host_key)
68{
69	char *chost;
70	struct passwd *pw = authctxt->pw;
71
72	debug("Trying rhosts with RSA host authentication for client user %.100s",
73	    cuser);
74
75	if (!authctxt->valid || client_host_key == NULL ||
76	    client_host_key->rsa == NULL)
77		return 0;
78
79	chost = __UNCONST(get_canonical_hostname(options.use_dns));
80	debug("Rhosts RSA authentication: canonical host %.900s", chost);
81
82	if (!PRIVSEP(auth_rhosts_rsa_key_allowed(pw, cuser, chost, client_host_key))) {
83		debug("Rhosts with RSA host authentication denied: unknown or invalid host key");
84		packet_send_debug("Your host key cannot be verified: unknown or invalid host key.");
85		return 0;
86	}
87	/* A matching host key was found and is known. */
88
89	/* Perform the challenge-response dialog with the client for the host key. */
90	if (!auth_rsa_challenge_dialog(client_host_key)) {
91		logit("Client on %.800s failed to respond correctly to host authentication.",
92		    chost);
93		return 0;
94	}
95	/*
96	 * We have authenticated the user using .rhosts or /etc/hosts.equiv,
97	 * and the host using RSA. We accept the authentication.
98	 */
99
100	verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.",
101	    pw->pw_name, cuser, chost);
102	packet_send_debug("Rhosts with RSA host authentication accepted.");
103	return 1;
104}
105