auth-rh-rsa.c revision 295367 
1/* $OpenBSD: auth-rh-rsa.c,v 1.44 2014/07/15 15:54:14 millert 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#ifdef WITH_SSH1
19
20#include <sys/types.h>
21
22#include <pwd.h>
23#include <stdarg.h>
24
25#include "packet.h"
26#include "uidswap.h"
27#include "log.h"
28#include "buffer.h"
29#include "misc.h"
30#include "servconf.h"
31#include "key.h"
32#include "hostfile.h"
33#include "pathnames.h"
34#include "auth.h"
35#include "canohost.h"
36#ifdef GSSAPI
37#include "ssh-gss.h"
38#endif
39#include "monitor_wrap.h"
40
41/* import */
42extern ServerOptions options;
43
44int
45auth_rhosts_rsa_key_allowed(struct passwd *pw, char *cuser, char *chost,
46    Key *client_host_key)
47{
48	HostStatus host_status;
49
50	if (auth_key_is_revoked(client_host_key))
51		return 0;
52
53	/* Check if we would accept it using rhosts authentication. */
54	if (!auth_rhosts(pw, cuser))
55		return 0;
56
57	host_status = check_key_in_hostfiles(pw, client_host_key,
58	    chost, _PATH_SSH_SYSTEM_HOSTFILE,
59	    options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
60
61	return (host_status == HOST_OK);
62}
63
64/*
65 * Tries to authenticate the user using the .rhosts file and the host using
66 * its host key.  Returns true if authentication succeeds.
67 */
68int
69auth_rhosts_rsa(Authctxt *authctxt, char *cuser, Key *client_host_key)
70{
71	char *chost;
72	struct passwd *pw = authctxt->pw;
73
74	debug("Trying rhosts with RSA host authentication for client user %.100s",
75	    cuser);
76
77	if (!authctxt->valid || client_host_key == NULL ||
78	    client_host_key->rsa == NULL)
79		return 0;
80
81	chost = (char *)get_canonical_hostname(options.use_dns);
82	debug("Rhosts RSA authentication: canonical host %.900s", chost);
83
84	if (!PRIVSEP(auth_rhosts_rsa_key_allowed(pw, cuser, chost, client_host_key))) {
85		debug("Rhosts with RSA host authentication denied: unknown or invalid host key");
86		packet_send_debug("Your host key cannot be verified: unknown or invalid host key.");
87		return 0;
88	}
89	/* A matching host key was found and is known. */
90
91	/* Perform the challenge-response dialog with the client for the host key. */
92	if (!auth_rsa_challenge_dialog(client_host_key)) {
93		logit("Client on %.800s failed to respond correctly to host authentication.",
94		    chost);
95		return 0;
96	}
97	/*
98	 * We have authenticated the user using .rhosts or /etc/hosts.equiv,
99	 * and the host using RSA. We accept the authentication.
100	 */
101
102	verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.",
103	    pw->pw_name, cuser, chost);
104	packet_send_debug("Rhosts with RSA host authentication accepted.");
105	return 1;
106}
107
108#endif /* WITH_SSH1 */
109