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 */
39extern ServerOptions options;
40
41int
42auth_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 */
65int
66auth_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