2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * Rhosts or /etc/hosts.equiv authentication combined with RSA host
8 * As far as I am concerned, the code I have written for this software
9 * can be used freely for any purpose. Any derived versions of this
10 * software must be clearly marked as such, and if the derived work is
11 * incompatible with the protocol description in the RFC file, it must be
12 * called by a name other than "ssh" or "Secure Shell".
16 RCSID("$OpenBSD: auth-rh-rsa.c,v 1.23 2001/04/06 21:00:04 markus Exp $");
25 #include "pathnames.h"
27 #include "tildexpand.h"
31 * Tries to authenticate the user using the .rhosts file and the host using
32 * its host key. Returns true if authentication succeeds.
36 auth_rhosts_rsa(struct passwd *pw, const char *client_user, RSA *client_host_key)
38 extern ServerOptions options;
39 const char *canonical_hostname;
40 HostStatus host_status;
41 Key *client_key, *found;
43 debug("Trying rhosts with RSA host authentication for client user %.100s", client_user);
45 if (pw == NULL || client_host_key == NULL)
48 /* Check if we would accept it using rhosts authentication. */
49 if (!auth_rhosts(pw, client_user))
52 canonical_hostname = get_canonical_hostname(
53 options.reverse_mapping_check);
55 debug("Rhosts RSA authentication: canonical host %.900s", canonical_hostname);
57 /* wrap the RSA key into a 'generic' key */
58 client_key = key_new(KEY_RSA1);
59 BN_copy(client_key->rsa->e, client_host_key->e);
60 BN_copy(client_key->rsa->n, client_host_key->n);
61 found = key_new(KEY_RSA1);
63 /* Check if we know the host and its host key. */
64 host_status = check_host_in_hostfile(_PATH_SSH_SYSTEM_HOSTFILE, canonical_hostname,
65 client_key, found, NULL);
67 /* Check user host file unless ignored. */
68 if (host_status != HOST_OK && !options.ignore_user_known_hosts) {
70 char *user_hostfile = tilde_expand_filename(_PATH_SSH_USER_HOSTFILE, pw->pw_uid);
72 * Check file permissions of _PATH_SSH_USER_HOSTFILE, auth_rsa()
73 * did already check pw->pw_dir, but there is a race XXX
75 if (options.strict_modes &&
76 (stat(user_hostfile, &st) == 0) &&
77 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
78 (st.st_mode & 022) != 0)) {
79 log("Rhosts RSA authentication refused for %.100s: bad owner or modes for %.200s",
80 pw->pw_name, user_hostfile);
82 /* XXX race between stat and the following open() */
83 temporarily_use_uid(pw);
84 host_status = check_host_in_hostfile(user_hostfile, canonical_hostname,
85 client_key, found, NULL);
93 if (host_status != HOST_OK) {
94 debug("Rhosts with RSA host authentication denied: unknown or invalid host key");
95 packet_send_debug("Your host key cannot be verified: unknown or invalid host key.");
98 /* A matching host key was found and is known. */
100 /* Perform the challenge-response dialog with the client for the host key. */
101 if (!auth_rsa_challenge_dialog(client_host_key)) {
102 log("Client on %.800s failed to respond correctly to host authentication.",
107 * We have authenticated the user using .rhosts or /etc/hosts.equiv,
108 * and the host using RSA. We accept the authentication.
111 verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.",
112 pw->pw_name, client_user, canonical_hostname);
113 packet_send_debug("Rhosts with RSA host authentication accepted.");