2 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * As far as I am concerned, the code I have written for this software
6 * can be used freely for any purpose. Any derived versions of this
7 * software must be clearly marked as such, and if the derived work is
8 * incompatible with the protocol description in the RFC file, it must be
9 * called by a name other than "ssh" or "Secure Shell".
13 RCSID("$OpenBSD: auth1.c,v 1.55 2003/11/08 16:02:40 jakob Exp $");
28 #include "monitor_wrap.h"
31 extern ServerOptions options;
34 * convert ssh auth msg type into description
37 get_authname(int type)
39 static char buf[1024];
41 case SSH_CMSG_AUTH_PASSWORD:
43 case SSH_CMSG_AUTH_RSA:
45 case SSH_CMSG_AUTH_RHOSTS_RSA:
47 case SSH_CMSG_AUTH_RHOSTS:
49 case SSH_CMSG_AUTH_TIS:
50 case SSH_CMSG_AUTH_TIS_RESPONSE:
51 return "challenge-response";
53 snprintf(buf, sizeof buf, "bad-auth-msg-%d", type);
58 * read packets, try to authenticate the user and
59 * return only if authentication is successful
62 do_authloop(Authctxt *authctxt)
64 int authenticated = 0;
68 char *client_user, *password;
73 struct passwd *pw = authctxt->pw;
75 debug("Attempting authentication for %s%.100s.",
76 authctxt->valid ? "" : "illegal user ", authctxt->user);
78 /* If the user has no password, accept authentication immediately. */
79 if (options.password_authentication &&
81 (!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
83 PRIVSEP(auth_password(authctxt, ""))) {
84 auth_log(authctxt, 1, "without authentication", "");
88 /* Indicate that authentication is needed. */
89 packet_start(SSH_SMSG_FAILURE);
101 /* Get a packet from the client. */
103 type = packet_read();
106 * If we started challenge-response authentication but the
107 * next packet is not a response to our challenge, release
108 * the resources allocated by get_challenge() (which would
109 * normally have been released by verify_response() had we
110 * received such a response)
112 if (prev == SSH_CMSG_AUTH_TIS &&
113 type != SSH_CMSG_AUTH_TIS_RESPONSE)
114 abandon_challenge_response(authctxt);
116 /* Process the packet. */
118 case SSH_CMSG_AUTH_RHOSTS_RSA:
119 if (!options.rhosts_rsa_authentication) {
120 verbose("Rhosts with RSA authentication disabled.");
124 * Get client user name. Note that we just have to
125 * trust the client; root on the client machine can
126 * claim to be any user.
128 client_user = packet_get_string(&ulen);
130 /* Get the client host key. */
131 client_host_key = key_new(KEY_RSA1);
132 bits = packet_get_int();
133 packet_get_bignum(client_host_key->rsa->e);
134 packet_get_bignum(client_host_key->rsa->n);
136 if (bits != BN_num_bits(client_host_key->rsa->n))
137 verbose("Warning: keysize mismatch for client_host_key: "
138 "actual %d, announced %d",
139 BN_num_bits(client_host_key->rsa->n), bits);
142 authenticated = auth_rhosts_rsa(authctxt, client_user,
144 key_free(client_host_key);
146 snprintf(info, sizeof info, " ruser %.100s", client_user);
149 case SSH_CMSG_AUTH_RSA:
150 if (!options.rsa_authentication) {
151 verbose("RSA authentication disabled.");
154 /* RSA authentication requested. */
155 if ((n = BN_new()) == NULL)
156 fatal("do_authloop: BN_new failed");
157 packet_get_bignum(n);
159 authenticated = auth_rsa(authctxt, n);
163 case SSH_CMSG_AUTH_PASSWORD:
164 if (!options.password_authentication) {
165 verbose("Password authentication disabled.");
169 * Read user password. It is in plain text, but was
170 * transmitted over the encrypted channel so it is
171 * not visible to an outside observer.
173 password = packet_get_string(&dlen);
176 /* Try authentication with the password. */
177 authenticated = PRIVSEP(auth_password(authctxt, password));
179 memset(password, 0, strlen(password));
183 case SSH_CMSG_AUTH_TIS:
184 debug("rcvd SSH_CMSG_AUTH_TIS");
185 if (options.challenge_response_authentication == 1) {
186 char *challenge = get_challenge(authctxt);
187 if (challenge != NULL) {
188 debug("sending challenge '%s'", challenge);
189 packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
190 packet_put_cstring(challenge);
198 case SSH_CMSG_AUTH_TIS_RESPONSE:
199 debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE");
200 if (options.challenge_response_authentication == 1) {
201 char *response = packet_get_string(&dlen);
203 authenticated = verify_response(authctxt, response);
204 memset(response, 'r', dlen);
211 * Any unknown messages will be ignored (and failure
212 * returned) during authentication.
214 logit("Unknown message during authentication: type %d", type);
219 auth_close(authctxt->as);
223 if (!authctxt->valid && authenticated)
224 fatal("INTERNAL ERROR: authenticated invalid user %s",
228 if (authenticated && cray_access_denied(authctxt->user)) {
230 fatal("Access denied for user %s.",authctxt->user);
236 !check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD, pw)) {
237 packet_disconnect("Authentication rejected for uid %d.",
238 pw == NULL ? -1 : pw->pw_uid);
242 /* Special handling for root */
243 if (authenticated && authctxt->pw->pw_uid == 0 &&
244 !auth_root_allowed(get_authname(type)))
249 if (options.use_pam && authenticated &&
250 !PRIVSEP(do_pam_account()))
254 /* Log before sending the reply */
255 auth_log(authctxt, authenticated, get_authname(type), info);
257 if (client_user != NULL) {
265 if (authctxt->failures++ > AUTH_FAIL_MAX)
266 packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
268 packet_start(SSH_SMSG_FAILURE);
275 * Performs authentication of an incoming connection. Session key has already
276 * been exchanged and encryption is enabled.
279 do_authentication(Authctxt *authctxt)
282 char *user, *style = NULL;
284 /* Get the name of the user that we wish to log in as. */
285 packet_read_expect(SSH_CMSG_USER);
287 /* Get the user name. */
288 user = packet_get_string(&ulen);
291 if ((style = strchr(user, ':')) != NULL)
294 authctxt->user = user;
295 authctxt->style = style;
297 /* Verify that the user is a valid user. */
298 if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL)
301 debug("do_authentication: illegal user %s", user);
302 authctxt->pw = fakepw();
305 setproctitle("%s%s", authctxt->pw ? user : "unknown",
306 use_privsep ? " [net]" : "");
310 PRIVSEP(start_pam(authctxt));
314 * If we are not running as root, the user must have the same uid as
315 * the server. (Unless you are running Windows)
318 if (!use_privsep && getuid() != 0 && authctxt->pw &&
319 authctxt->pw->pw_uid != getuid())
320 packet_disconnect("Cannot change user when server not running as root.");
324 * Loop until the user has been authenticated or the connection is
325 * closed, do_authloop() returns only if authentication is successful
327 do_authloop(authctxt);
329 /* The user has been authenticated and accepted. */
330 packet_start(SSH_SMSG_SUCCESS);