2 * Copyright (c) 2000 Markus Friedl. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 RCSID("$OpenBSD: auth2.c,v 1.93 2002/05/31 11:35:15 markus Exp $");
36 #include "pathnames.h"
37 #include "monitor_wrap.h"
40 extern ServerOptions options;
41 extern u_char *session_id2;
42 extern int session_id2_len;
44 Authctxt *x_authctxt = NULL;
48 extern Authmethod method_none;
49 extern Authmethod method_pubkey;
50 extern Authmethod method_passwd;
51 extern Authmethod method_kbdint;
52 extern Authmethod method_hostbased;
54 Authmethod *authmethods[] = {
65 static void input_service_request(int, u_int32_t, void *);
66 static void input_userauth_request(int, u_int32_t, void *);
69 static Authmethod *authmethod_lookup(const char *);
70 static char *authmethods_get(void);
71 int user_key_allowed(struct passwd *, Key *);
72 int hostbased_key_allowed(struct passwd *, const char *, char *, Key *);
75 * loop until authctxt->success == TRUE
79 do_authentication2(void)
81 Authctxt *authctxt = authctxt_new();
83 x_authctxt = authctxt; /*XXX*/
85 /* challenge-response is implemented via keyboard interactive */
86 if (options.challenge_response_authentication)
87 options.kbd_interactive_authentication = 1;
88 if (options.pam_authentication_via_kbd_int)
89 options.kbd_interactive_authentication = 1;
91 options.pam_authentication_via_kbd_int = 0;
93 dispatch_init(&dispatch_protocol_error);
94 dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
95 dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
101 input_service_request(int type, u_int32_t seq, void *ctxt)
103 Authctxt *authctxt = ctxt;
106 char *service = packet_get_string(&len);
109 if (authctxt == NULL)
110 fatal("input_service_request: no authctxt");
112 if (strcmp(service, "ssh-userauth") == 0) {
113 if (!authctxt->success) {
115 /* now we can handle user-auth requests */
116 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
119 /* XXX all other service requests are denied */
122 packet_start(SSH2_MSG_SERVICE_ACCEPT);
123 packet_put_cstring(service);
127 debug("bad service request %s", service);
128 packet_disconnect("bad service request %s", service);
134 input_userauth_request(int type, u_int32_t seq, void *ctxt)
136 Authctxt *authctxt = ctxt;
137 Authmethod *m = NULL;
138 char *user, *service, *method, *style = NULL;
139 int authenticated = 0;
141 if (authctxt == NULL)
142 fatal("input_userauth_request: no authctxt");
144 user = packet_get_string(NULL);
145 service = packet_get_string(NULL);
146 method = packet_get_string(NULL);
147 debug("userauth-request for user %s service %s method %s", user, service, method);
148 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
150 if ((style = strchr(user, ':')) != NULL)
153 if (authctxt->attempt++ == 0) {
154 /* setup auth context */
155 authctxt->pw = PRIVSEP(getpwnamallow(user));
156 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
158 debug2("input_userauth_request: setting up authctxt for %s", user);
160 PRIVSEP(start_pam(authctxt->pw->pw_name));
163 log("input_userauth_request: illegal user %s", user);
165 PRIVSEP(start_pam("NOUSER"));
168 setproctitle("%s%s", authctxt->pw ? user : "unknown",
169 use_privsep ? " [net]" : "");
170 authctxt->user = xstrdup(user);
171 authctxt->service = xstrdup(service);
172 authctxt->style = style ? xstrdup(style) : NULL;
174 mm_inform_authserv(service, style);
175 } else if (strcmp(user, authctxt->user) != 0 ||
176 strcmp(service, authctxt->service) != 0) {
177 packet_disconnect("Change of username or service not allowed: "
178 "(%s,%s) -> (%s,%s)",
179 authctxt->user, authctxt->service, user, service);
182 auth2_challenge_stop(authctxt);
183 authctxt->postponed = 0;
185 /* try to authenticate user */
186 m = authmethod_lookup(method);
188 debug2("input_userauth_request: try method %s", method);
189 authenticated = m->userauth(authctxt);
191 userauth_finish(authctxt, authenticated, method);
199 userauth_finish(Authctxt *authctxt, int authenticated, char *method)
203 if (!authctxt->valid && authenticated)
204 fatal("INTERNAL ERROR: authenticated invalid user %s",
207 /* Special handling for root */
208 if (authenticated && authctxt->pw->pw_uid == 0 &&
209 !auth_root_allowed(method))
213 if (!use_privsep && authenticated && authctxt->user &&
214 !do_pam_account(authctxt->user, NULL))
218 /* Log before sending the reply */
219 auth_log(authctxt, authenticated, method, " ssh2");
221 if (authctxt->postponed)
224 /* XXX todo: check if multiple auth methods are needed */
225 if (authenticated == 1) {
226 /* turn off userauth */
227 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
228 packet_start(SSH2_MSG_USERAUTH_SUCCESS);
231 /* now we can break out */
232 authctxt->success = 1;
234 if (authctxt->failures++ > AUTH_FAIL_MAX) {
235 #ifdef WITH_AIXAUTHENTICATE
236 loginfailed(authctxt->user,
237 get_canonical_hostname(options.verify_reverse_mapping),
239 #endif /* WITH_AIXAUTHENTICATE */
240 packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
242 methods = authmethods_get();
243 packet_start(SSH2_MSG_USERAUTH_FAILURE);
244 packet_put_cstring(methods);
245 packet_put_char(0); /* XXX partial success, unused */
253 auth2_read_banner(void)
260 if ((fd = open(options.banner, O_RDONLY)) == -1)
262 if (fstat(fd, &st) == -1) {
267 banner = xmalloc(len + 1);
268 n = atomicio(read, fd, banner, len);
281 userauth_banner(void)
285 if (options.banner == NULL || (datafellows & SSH_BUG_BANNER))
288 if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
291 packet_start(SSH2_MSG_USERAUTH_BANNER);
292 packet_put_cstring(banner);
293 packet_put_cstring(""); /* language, unused */
295 debug("userauth_banner: sent");
303 userauth_none(Authctxt *authctxt)
305 /* disable method "none", only allowed one time */
306 Authmethod *m = authmethod_lookup("none");
312 if (authctxt->valid == 0)
316 if (check_nt_auth(1, authctxt->pw) == 0)
319 return PRIVSEP(auth_password(authctxt, ""));
323 userauth_passwd(Authctxt *authctxt)
326 int authenticated = 0;
329 change = packet_get_char();
331 log("password change not supported");
332 password = packet_get_string(&len);
334 if (authctxt->valid &&
336 check_nt_auth(1, authctxt->pw) &&
338 PRIVSEP(auth_password(authctxt, password)) == 1)
340 memset(password, 0, len);
342 return authenticated;
346 userauth_kbdint(Authctxt *authctxt)
348 int authenticated = 0;
351 lang = packet_get_string(NULL);
352 devs = packet_get_string(NULL);
355 debug("keyboard-interactive devs %s", devs);
357 if (options.challenge_response_authentication)
358 authenticated = auth2_challenge(authctxt, devs);
361 if (authenticated == 0 && options.pam_authentication_via_kbd_int)
362 authenticated = auth2_pam(authctxt);
367 if (check_nt_auth(0, authctxt->pw) == 0)
370 return authenticated;
374 userauth_pubkey(Authctxt *authctxt)
379 u_char *pkblob, *sig;
380 u_int alen, blen, slen;
381 int have_sig, pktype;
382 int authenticated = 0;
384 if (!authctxt->valid) {
385 debug2("userauth_pubkey: disabled because of invalid user");
388 have_sig = packet_get_char();
389 if (datafellows & SSH_BUG_PKAUTH) {
390 debug2("userauth_pubkey: SSH_BUG_PKAUTH");
391 /* no explicit pkalg given */
392 pkblob = packet_get_string(&blen);
394 buffer_append(&b, pkblob, blen);
395 /* so we have to extract the pkalg from the pkblob */
396 pkalg = buffer_get_string(&b, &alen);
399 pkalg = packet_get_string(&alen);
400 pkblob = packet_get_string(&blen);
402 pktype = key_type_from_name(pkalg);
403 if (pktype == KEY_UNSPEC) {
404 /* this is perfectly legal */
405 log("userauth_pubkey: unsupported public key algorithm: %s",
409 key = key_from_blob(pkblob, blen);
411 error("userauth_pubkey: cannot decode key: %s", pkalg);
414 if (key->type != pktype) {
415 error("userauth_pubkey: type mismatch for decoded key "
416 "(received %d, expected %d)", key->type, pktype);
420 sig = packet_get_string(&slen);
423 if (datafellows & SSH_OLD_SESSIONID) {
424 buffer_append(&b, session_id2, session_id2_len);
426 buffer_put_string(&b, session_id2, session_id2_len);
428 /* reconstruct packet */
429 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
430 buffer_put_cstring(&b, authctxt->user);
431 buffer_put_cstring(&b,
432 datafellows & SSH_BUG_PKSERVICE ?
435 if (datafellows & SSH_BUG_PKAUTH) {
436 buffer_put_char(&b, have_sig);
438 buffer_put_cstring(&b, "publickey");
439 buffer_put_char(&b, have_sig);
440 buffer_put_cstring(&b, pkalg);
442 buffer_put_string(&b, pkblob, blen);
446 /* test for correct signature */
448 if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
449 PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
450 buffer_len(&b))) == 1)
455 debug("test whether pkalg/pkblob are acceptable");
458 /* XXX fake reply and always send PK_OK ? */
460 * XXX this allows testing whether a user is allowed
461 * to login: if you happen to have a valid pubkey this
462 * message is sent. the message is NEVER sent at all
463 * if a user is not allowed to login. is this an
466 if (PRIVSEP(user_key_allowed(authctxt->pw, key))) {
467 packet_start(SSH2_MSG_USERAUTH_PK_OK);
468 packet_put_string(pkalg, alen);
469 packet_put_string(pkblob, blen);
472 authctxt->postponed = 1;
475 if (authenticated != 1)
476 auth_clear_options();
478 debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
484 if (check_nt_auth(0, authctxt->pw) == 0)
487 return authenticated;
491 userauth_hostbased(Authctxt *authctxt)
495 char *pkalg, *cuser, *chost, *service;
496 u_char *pkblob, *sig;
497 u_int alen, blen, slen;
499 int authenticated = 0;
501 if (!authctxt->valid) {
502 debug2("userauth_hostbased: disabled because of invalid user");
505 pkalg = packet_get_string(&alen);
506 pkblob = packet_get_string(&blen);
507 chost = packet_get_string(NULL);
508 cuser = packet_get_string(NULL);
509 sig = packet_get_string(&slen);
511 debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d",
512 cuser, chost, pkalg, slen);
516 buffer_append(&b, sig, slen);
520 pktype = key_type_from_name(pkalg);
521 if (pktype == KEY_UNSPEC) {
522 /* this is perfectly legal */
523 log("userauth_hostbased: unsupported "
524 "public key algorithm: %s", pkalg);
527 key = key_from_blob(pkblob, blen);
529 error("userauth_hostbased: cannot decode key: %s", pkalg);
532 if (key->type != pktype) {
533 error("userauth_hostbased: type mismatch for decoded key "
534 "(received %d, expected %d)", key->type, pktype);
537 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
540 buffer_put_string(&b, session_id2, session_id2_len);
541 /* reconstruct packet */
542 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
543 buffer_put_cstring(&b, authctxt->user);
544 buffer_put_cstring(&b, service);
545 buffer_put_cstring(&b, "hostbased");
546 buffer_put_string(&b, pkalg, alen);
547 buffer_put_string(&b, pkblob, blen);
548 buffer_put_cstring(&b, chost);
549 buffer_put_cstring(&b, cuser);
553 /* test for allowed key and correct signature */
555 if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
556 PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
557 buffer_len(&b))) == 1)
562 debug2("userauth_hostbased: authenticated %d", authenticated);
570 return authenticated;
573 /* get current user */
578 return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL;
584 authmethods_get(void)
591 for (i = 0; authmethods[i] != NULL; i++) {
592 if (strcmp(authmethods[i]->name, "none") == 0)
594 if (authmethods[i]->enabled != NULL &&
595 *(authmethods[i]->enabled) != 0) {
596 if (buffer_len(&b) > 0)
597 buffer_append(&b, ",", 1);
598 buffer_append(&b, authmethods[i]->name,
599 strlen(authmethods[i]->name));
602 buffer_append(&b, "\0", 1);
603 list = xstrdup(buffer_ptr(&b));
609 authmethod_lookup(const char *name)
614 for (i = 0; authmethods[i] != NULL; i++)
615 if (authmethods[i]->enabled != NULL &&
616 *(authmethods[i]->enabled) != 0 &&
617 strcmp(name, authmethods[i]->name) == 0)
618 return authmethods[i];
619 debug2("Unrecognized authentication method name: %s",
620 name ? name : "NULL");