auth-rh-rsa.c revision 162856 
1/* $OpenBSD: auth-rh-rsa.c,v 1.42 2006/08/03 03:34:41 deraadt 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	/* Check if we would accept it using rhosts authentication. */
48	if (!auth_rhosts(pw, cuser))
49		return 0;
50
51	host_status = check_key_in_hostfiles(pw, client_host_key,
52	    chost, _PATH_SSH_SYSTEM_HOSTFILE,
53	    options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
54
55	return (host_status == HOST_OK);
56}
57
58/*
59 * Tries to authenticate the user using the .rhosts file and the host using
60 * its host key.  Returns true if authentication succeeds.
61 */
62int
63auth_rhosts_rsa(Authctxt *authctxt, char *cuser, Key *client_host_key)
64{
65	char *chost;
66	struct passwd *pw = authctxt->pw;
67
68	debug("Trying rhosts with RSA host authentication for client user %.100s",
69	    cuser);
70
71	if (!authctxt->valid || client_host_key == NULL ||
72	    client_host_key->rsa == NULL)
73		return 0;
74
75	chost = (char *)get_canonical_hostname(options.use_dns);
76	debug("Rhosts RSA authentication: canonical host %.900s", chost);
77
78	if (!PRIVSEP(auth_rhosts_rsa_key_allowed(pw, cuser, chost, client_host_key))) {
79		debug("Rhosts with RSA host authentication denied: unknown or invalid host key");
80		packet_send_debug("Your host key cannot be verified: unknown or invalid host key.");
81		return 0;
82	}
83	/* A matching host key was found and is known. */
84
85	/* Perform the challenge-response dialog with the client for the host key. */
86	if (!auth_rsa_challenge_dialog(client_host_key)) {
87		logit("Client on %.800s failed to respond correctly to host authentication.",
88		    chost);
89		return 0;
90	}
91	/*
92	 * We have authenticated the user using .rhosts or /etc/hosts.equiv,
93	 * and the host using RSA. We accept the authentication.
94	 */
95
96	verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.",
97	    pw->pw_name, cuser, chost);
98	packet_send_debug("Rhosts with RSA host authentication accepted.");
99	return 1;
100}
101