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 1.52 2003/08/28 12:54:34 markus Exp $");
29 #include "monitor_wrap.h"
32 extern ServerOptions options;
36 #include "globus_gss_assist.h"
39 extern Authmethod method_gssapi;
41 int userauth_gssapi(Authctxt *authctxt);
44 auth1_gss_protocol_error(int type, u_int32_t plen, void *ctxt)
46 Authctxt *authctxt = ctxt;
47 /* Other side told us to abort, dont need to tell him */
48 /* maybe we can use some other method. */
49 if (type == SSH_MSG_AUTH_GSSAPI_ABORT) {
50 logit("auth1: GSSAPI aborting");
51 dispatch_set(SSH_MSG_AUTH_GSSAPI_TOKEN, NULL);
52 authctxt->success = 1; /* get out of loop*/
56 logit("auth1: protocol error: type %d plen %d", type, plen);
57 packet_disconnect("Protocol error during GSSAPI authentication: "
58 "Unknown packet type %d", type);
63 gsi_gridmap(char *subject_name, char **mapped_name)
65 #ifdef GLOBUS_GSI_GSS_ASSIST_MODULE
66 if (globus_module_activate(GLOBUS_GSI_GSS_ASSIST_MODULE) != 0) {
70 return(globus_gss_assist_gridmap(subject_name, mapped_name) == 0);
75 * SSH1 GSSAPI clients may send us a user name of the form:
77 * (1) username:x:SSL Subject Name
79 * (2) username:i:SSL Subject Name
83 * if case 1, then uname is an explicit name (ssh -l uname). Keep this
84 * name always, rewrite the user parameter to be just uname. We'll pull
85 * the GSSAPI idenity out and deal with (or skip it) later.
87 * if case 2, then uname is implicit (user didn't use the -l option), so
88 * use the default gridmap mapping and replace uname with whatever
89 * the gridmap maps to. If the gridmap mapping fails, drop down
92 * if case 3, then leave it be.
94 * This function may return the original pointer to the orginal string,
95 * the original pointer to a modified string, or a completely new pointer.
98 ssh1_gssapi_parse_userstring(char *userstring)
100 char name_type = '\0'; /* explicit 'x' or implicit 'i' */
101 char *ssl_subject_name = NULL;
104 debug("Looking at username '%s' for gssapi-ssleay type name", userstring);
105 if((delim = strchr(userstring, ':')) != NULL) {
106 /* Parse and split into components */
107 ssl_subject_name = strchr(delim + 1, ':');
109 if (ssl_subject_name) {
110 /* Successful parse, split into components */
112 name_type = *(delim + 1);
113 *ssl_subject_name = '\0';
116 debug("Name parsed. type = '%c'. ssl subject name is \"%s\"",
117 name_type, ssl_subject_name);
121 debug("Don't understand name format. Letting it pass.");
126 if(ssl_subject_name) {
127 char *gridmapped_name = NULL;
130 debug("explicit name given, using %s as username", userstring);
135 debug("implicit name given. gridmapping '%s'", ssl_subject_name);
137 PRIVSEP(gsi_gridmap(ssl_subject_name, &gridmapped_name));
138 if (gridmapped_name && gridmapped_name[0] != '\0') {
139 userstring = gridmapped_name;
140 debug("I gridmapped and got %s", userstring);
143 debug("I gridmapped and got null, reverting to %s", userstring);
148 debug("Unknown name type '%c'. Ignoring.", name_type);
152 debug("didn't find any :'s so I assume it's just a user name");
161 * convert ssh auth msg type into description
164 get_authname(int type)
166 static char buf[1024];
168 case SSH_CMSG_AUTH_PASSWORD:
170 case SSH_CMSG_AUTH_RSA:
172 case SSH_CMSG_AUTH_RHOSTS_RSA:
174 case SSH_CMSG_AUTH_RHOSTS:
176 case SSH_CMSG_AUTH_TIS:
177 case SSH_CMSG_AUTH_TIS_RESPONSE:
178 return "challenge-response";
180 case SSH_CMSG_AUTH_GSSAPI:
184 snprintf(buf, sizeof buf, "bad-auth-msg-%d", type);
189 * read packets, try to authenticate the user and
190 * return only if authentication is successful
193 do_authloop(Authctxt *authctxt)
195 int authenticated = 0;
197 Key *client_host_key;
199 char *client_user, *password;
204 struct passwd *pw = authctxt->pw;
206 debug("Attempting authentication for %s%.100s.",
207 authctxt->valid ? "" : "illegal user ", authctxt->user);
209 /* If the user has no password, accept authentication immediately. */
210 if (options.password_authentication &&
212 (!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
214 PRIVSEP(auth_password(authctxt, ""))) {
215 auth_log(authctxt, 1, "without authentication", "");
219 /* Indicate that authentication is needed. */
220 packet_start(SSH_SMSG_FAILURE);
227 /* default to fail */
232 /* Get a packet from the client. */
234 type = packet_read();
237 * If we started challenge-response authentication but the
238 * next packet is not a response to our challenge, release
239 * the resources allocated by get_challenge() (which would
240 * normally have been released by verify_response() had we
241 * received such a response)
243 if (prev == SSH_CMSG_AUTH_TIS &&
244 type != SSH_CMSG_AUTH_TIS_RESPONSE)
245 abandon_challenge_response(authctxt);
247 /* Process the packet. */
250 case SSH_CMSG_AUTH_GSSAPI:
251 if (!options.gss_authentication) {
252 verbose("GSSAPI authentication disabled.");
256 * GSSAPI was first added to ssh1 in ssh-1.2.27, and
257 * was added to the SecurtCRT product. In order
258 * to continue operating with these, we will add
259 * the equivelent GSSAPI support to SSH1.
260 * Will use the gssapi routines from the ssh2 as
261 * they are almost identical. But they use dispatch
262 * so we need to setup the dispatch tables here
263 * auth1.c for use only by the gssapi code.
264 * Since we already have the packet, we will call
265 * userauth_gssapi then start the dispatch loop.
267 if (!authctxt->valid) {
268 packet_disconnect("Authentication rejected for invalid user");
270 dispatch_init(&auth1_gss_protocol_error);
271 method_gssapi.userauth(authctxt);
272 if (!authctxt->postponed) { /* failed before starting dispatch */
273 authctxt->success = 0;
274 authctxt->postponed = 0;
277 dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
278 if (authctxt->postponed) { /* failed, try other methods */
279 authctxt->success = 0;
280 authctxt->postponed = 0;
287 case SSH_CMSG_AUTH_RHOSTS_RSA:
288 if (!options.rhosts_rsa_authentication) {
289 verbose("Rhosts with RSA authentication disabled.");
293 * Get client user name. Note that we just have to
294 * trust the client; root on the client machine can
295 * claim to be any user.
297 client_user = packet_get_string(&ulen);
299 /* Get the client host key. */
300 client_host_key = key_new(KEY_RSA1);
301 bits = packet_get_int();
302 packet_get_bignum(client_host_key->rsa->e);
303 packet_get_bignum(client_host_key->rsa->n);
305 if (bits != BN_num_bits(client_host_key->rsa->n))
306 verbose("Warning: keysize mismatch for client_host_key: "
307 "actual %d, announced %d",
308 BN_num_bits(client_host_key->rsa->n), bits);
311 authenticated = auth_rhosts_rsa(pw, client_user,
313 key_free(client_host_key);
315 snprintf(info, sizeof info, " ruser %.100s", client_user);
318 case SSH_CMSG_AUTH_RSA:
319 if (!options.rsa_authentication) {
320 verbose("RSA authentication disabled.");
323 /* RSA authentication requested. */
324 if ((n = BN_new()) == NULL)
325 fatal("do_authloop: BN_new failed");
326 packet_get_bignum(n);
328 authenticated = auth_rsa(pw, n);
332 case SSH_CMSG_AUTH_PASSWORD:
333 if (!options.password_authentication) {
334 verbose("Password authentication disabled.");
338 * Read user password. It is in plain text, but was
339 * transmitted over the encrypted channel so it is
340 * not visible to an outside observer.
342 password = packet_get_string(&dlen);
345 /* Try authentication with the password. */
346 authenticated = PRIVSEP(auth_password(authctxt, password));
348 memset(password, 0, strlen(password));
352 case SSH_CMSG_AUTH_TIS:
353 debug("rcvd SSH_CMSG_AUTH_TIS");
354 if (options.challenge_response_authentication == 1) {
355 char *challenge = get_challenge(authctxt);
356 if (challenge != NULL) {
357 debug("sending challenge '%s'", challenge);
358 packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
359 packet_put_cstring(challenge);
367 case SSH_CMSG_AUTH_TIS_RESPONSE:
368 debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE");
369 if (options.challenge_response_authentication == 1) {
370 char *response = packet_get_string(&dlen);
372 authenticated = verify_response(authctxt, response);
373 memset(response, 'r', dlen);
380 * Any unknown messages will be ignored (and failure
381 * returned) during authentication.
383 logit("Unknown message during authentication: type %d", type);
388 auth_close(authctxt->as);
392 if (!authctxt->valid && authenticated)
393 fatal("INTERNAL ERROR: authenticated invalid user %s",
397 if (authenticated && cray_access_denied(authctxt->user)) {
399 fatal("Access denied for user %s.",authctxt->user);
405 !check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD, pw)) {
406 packet_disconnect("Authentication rejected for uid %d.",
407 pw == NULL ? -1 : pw->pw_uid);
411 /* Special handling for root */
412 if (authenticated && authctxt->pw->pw_uid == 0 &&
413 !auth_root_allowed(get_authname(type)))
418 if (options.use_pam && authenticated &&
419 !PRIVSEP(do_pam_account()))
423 /* Log before sending the reply */
424 auth_log(authctxt, authenticated, get_authname(type), info);
426 if (client_user != NULL) {
434 if (authctxt->failures++ > AUTH_FAIL_MAX)
435 packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
437 packet_start(SSH_SMSG_FAILURE);
444 * Performs authentication of an incoming connection. Session key has already
445 * been exchanged and encryption is enabled.
448 do_authentication(void)
452 char *user, *style = NULL;
454 /* Get the name of the user that we wish to log in as. */
455 packet_read_expect(SSH_CMSG_USER);
457 /* Get the user name. */
458 user = packet_get_string(&ulen);
462 /* Parse GSSAPI identity from userstring */
463 user = ssh1_gssapi_parse_userstring(user);
466 if ((style = strchr(user, ':')) != NULL)
469 authctxt = authctxt_new();
470 authctxt->user = user;
471 authctxt->style = style;
473 /* Verify that the user is a valid user. */
474 if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL)
477 debug("do_authentication: illegal user %s", user);
478 authctxt->pw = fakepw();
481 setproctitle("%s%s", authctxt->pw ? user : "unknown",
482 use_privsep ? " [net]" : "");
486 PRIVSEP(start_pam(user));
490 * If we are not running as root, the user must have the same uid as
491 * the server. (Unless you are running Windows)
494 if (!use_privsep && getuid() != 0 && authctxt->pw &&
495 authctxt->pw->pw_uid != getuid())
496 packet_disconnect("Cannot change user when server not running as root.");
500 * Loop until the user has been authenticated or the connection is
501 * closed, do_authloop() returns only if authentication is successful
503 do_authloop(authctxt);
505 /* The user has been authenticated and accepted. */
506 packet_start(SSH_SMSG_SUCCESS);