auth-rh-rsa.c revision 60576 
1/*
2 *
3 * auth-rh-rsa.c
4 *
5 * Author: Tatu Ylonen <ylo@cs.hut.fi>
6 *
7 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
8 *                    All rights reserved
9 *
10 * Created: Sun May  7 03:08:06 1995 ylo
11 *
12 * Rhosts or /etc/hosts.equiv authentication combined with RSA host
13 * authentication.
14 *
15 * $FreeBSD: head/crypto/openssh/auth-rh-rsa.c 60576 2000-05-15 05:24:25Z kris $
16 */
17
18#include "includes.h"
19RCSID("$Id: auth-rh-rsa.c,v 1.13 2000/04/14 10:30:29 markus Exp $");
20
21#include "packet.h"
22#include "ssh.h"
23#include "xmalloc.h"
24#include "uidswap.h"
25#include "servconf.h"
26
27#include <openssl/rsa.h>
28#include <openssl/dsa.h>
29#include "key.h"
30#include "hostfile.h"
31
32/*
33 * Tries to authenticate the user using the .rhosts file and the host using
34 * its host key.  Returns true if authentication succeeds.
35 */
36
37int
38auth_rhosts_rsa(struct passwd *pw, const char *client_user, RSA *client_host_key)
39{
40	extern ServerOptions options;
41	const char *canonical_hostname;
42	HostStatus host_status;
43	Key *client_key, *found;
44
45	debug("Trying rhosts with RSA host authentication for %.100s", client_user);
46
47	if (client_host_key == NULL)
48		return 0;
49
50	/* Check if we would accept it using rhosts authentication. */
51	if (!auth_rhosts(pw, client_user))
52		return 0;
53
54	canonical_hostname = get_canonical_hostname();
55
56	debug("Rhosts RSA authentication: canonical host %.900s", canonical_hostname);
57
58	/* wrap the RSA key into a 'generic' key */
59	client_key = key_new(KEY_RSA);
60	BN_copy(client_key->rsa->e, client_host_key->e);
61	BN_copy(client_key->rsa->n, client_host_key->n);
62	found = key_new(KEY_RSA);
63
64	/* Check if we know the host and its host key. */
65	host_status = check_host_in_hostfile(SSH_SYSTEM_HOSTFILE, canonical_hostname,
66	    client_key, found);
67
68	/* Check user host file unless ignored. */
69	if (host_status != HOST_OK && !options.ignore_user_known_hosts) {
70		struct stat st;
71		char *user_hostfile = tilde_expand_filename(SSH_USER_HOSTFILE, pw->pw_uid);
72		/*
73		 * Check file permissions of SSH_USER_HOSTFILE, auth_rsa()
74		 * did already check pw->pw_dir, but there is a race XXX
75		 */
76		if (options.strict_modes &&
77		    (stat(user_hostfile, &st) == 0) &&
78		    ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
79		     (st.st_mode & 022) != 0)) {
80			log("Rhosts RSA authentication refused for %.100s: bad owner or modes for %.200s",
81			    pw->pw_name, user_hostfile);
82		} else {
83			/* XXX race between stat and the following open() */
84			temporarily_use_uid(pw->pw_uid);
85			host_status = check_host_in_hostfile(user_hostfile, canonical_hostname,
86			    client_key, found);
87			restore_uid();
88		}
89		xfree(user_hostfile);
90	}
91	key_free(client_key);
92	key_free(found);
93
94	if (host_status != HOST_OK) {
95		debug("Rhosts with RSA host authentication denied: unknown or invalid host key");
96		packet_send_debug("Your host key cannot be verified: unknown or invalid host key.");
97		return 0;
98	}
99	/* A matching host key was found and is known. */
100
101	/* Perform the challenge-response dialog with the client for the host key. */
102	if (!auth_rsa_challenge_dialog(client_host_key)) {
103		log("Client on %.800s failed to respond correctly to host authentication.",
104		    canonical_hostname);
105		return 0;
106	}
107	/*
108	 * We have authenticated the user using .rhosts or /etc/hosts.equiv,
109	 * and the host using RSA. We accept the authentication.
110	 */
111
112	verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.",
113	   pw->pw_name, client_user, canonical_hostname);
114	packet_send_debug("Rhosts with RSA host authentication accepted.");
115	return 1;
116}
117