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 1.14 2000/09/07 20:27:49 deraadt Exp $");
28 #include <openssl/dsa.h>
29 #include <openssl/rsa.h>
30 #include <openssl/evp.h>
53 #include "auth-options.h"
61 extern ServerOptions options;
62 extern unsigned char *session_id2;
63 extern int session_id2_len;
67 void input_service_request(int type, int plen);
68 void input_userauth_request(int type, int plen);
69 void protocol_error(int type, int plen);
72 int ssh2_auth_none(struct passwd *pw);
73 int ssh2_auth_password(struct passwd *pw);
74 int ssh2_auth_pubkey(struct passwd *pw, char *service);
77 struct passwd* auth_set_user(char *u, char *s);
78 int user_dsa_key_allowed(struct passwd *pw, Key *key);
80 typedef struct Authctxt Authctxt;
87 static Authctxt *authctxt = NULL;
88 static int userauth_success = 0;
91 * loop until userauth_success == TRUE
97 /* turn off skey/kerberos, not supported by SSH2 */
99 options.skey_authentication = 0;
102 options.kerberos_authentication = 0;
105 dispatch_init(&protocol_error);
106 dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
107 dispatch_run(DISPATCH_BLOCK, &userauth_success);
112 protocol_error(int type, int plen)
114 log("auth: protocol error: type %d plen %d", type, plen);
115 packet_start(SSH2_MSG_UNIMPLEMENTED);
122 input_service_request(int type, int plen)
126 char *service = packet_get_string(&len);
129 if (strcmp(service, "ssh-userauth") == 0) {
130 if (!userauth_success) {
132 /* now we can handle user-auth requests */
133 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
136 /* XXX all other service requests are denied */
139 packet_start(SSH2_MSG_SERVICE_ACCEPT);
140 packet_put_cstring(service);
144 debug("bad service request %s", service);
145 packet_disconnect("bad service request %s", service);
151 input_userauth_request(int type, int plen)
153 static void (*authlog) (const char *fmt,...) = verbose;
154 static int attempt = 0;
156 int authenticated = 0;
157 char *user, *service, *method, *authmsg = NULL;
159 #ifdef WITH_AIXAUTHENTICATE
160 extern char *aixloginmsg;
161 #endif /* WITH_AIXAUTHENTICATE */
163 user = packet_get_string(&len);
164 service = packet_get_string(&len);
165 method = packet_get_string(&len);
166 if (++attempt == AUTH_FAIL_MAX) {
167 #ifdef WITH_AIXAUTHENTICATE
168 loginfailed(user,get_canonical_hostname(),"ssh");
169 #endif /* WITH_AIXAUTHENTICATE */
170 packet_disconnect("too many failed userauth_requests");
172 debug("userauth-request for user %s service %s method %s", user, service, method);
174 /* XXX we only allow the ssh-connection service */
175 pw = auth_set_user(user, service);
176 if (pw && strcmp(service, "ssh-connection")==0) {
177 if (strcmp(method, "none") == 0) {
178 authenticated = ssh2_auth_none(pw);
179 } else if (strcmp(method, "password") == 0) {
180 authenticated = ssh2_auth_password(pw);
181 } else if (strcmp(method, "publickey") == 0) {
182 authenticated = ssh2_auth_pubkey(pw, service);
185 if (authenticated && pw && pw->pw_uid == 0 && !options.permit_root_login) {
187 log("ROOT LOGIN REFUSED FROM %.200s",
188 get_canonical_hostname());
192 if (authenticated && !do_pam_account(pw->pw_name, NULL))
196 /* Raise logging level */
197 if (authenticated == 1 ||
198 attempt == AUTH_FAIL_LOG ||
199 strcmp(method, "password") == 0)
202 /* Log before sending the reply */
203 if (authenticated == 1) {
204 authmsg = "Accepted";
205 } else if (authenticated == 0) {
208 authmsg = "Postponed";
210 authlog("%s %s for %.200s from %.200s port %d ssh2",
213 pw && pw->pw_uid == 0 ? "ROOT" : user,
217 /* XXX todo: check if multiple auth methods are needed */
218 if (authenticated == 1) {
219 #ifdef WITH_AIXAUTHENTICATE
220 /* We don't have a pty yet, so just label the line as "ssh" */
221 if (loginsuccess(user,get_canonical_hostname(),"ssh",
224 #endif /* WITH_AIXAUTHENTICATE */
225 /* turn off userauth */
226 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &protocol_error);
227 packet_start(SSH2_MSG_USERAUTH_SUCCESS);
230 /* now we can break out */
231 userauth_success = 1;
232 } else if (authenticated == 0) {
233 packet_start(SSH2_MSG_USERAUTH_FAILURE);
234 packet_put_cstring("publickey,password"); /* XXX dynamic */
235 packet_put_char(0); /* XXX partial success, unused */
246 ssh2_auth_none(struct passwd *pw)
249 extern int saved_argc;
250 extern char **saved_argv;
256 return auth_pam_password(pw, "");
257 #elif defined(HAVE_OSF_SIA)
258 return(sia_validate_user(NULL, saved_argc, saved_argv,
259 get_canonical_hostname(), pw->pw_name, NULL, 0, NULL,
261 #else /* !HAVE_OSF_SIA && !USE_PAM */
262 return auth_password(pw, "");
266 ssh2_auth_password(struct passwd *pw)
269 int authenticated = 0;
273 extern int saved_argc;
274 extern char **saved_argv;
276 change = packet_get_char();
278 log("password change not supported");
279 password = packet_get_string(&len);
281 if (options.password_authentication &&
283 auth_pam_password(pw, password) == 1)
284 #elif defined(HAVE_OSF_SIA)
285 sia_validate_user(NULL, saved_argc, saved_argv,
286 get_canonical_hostname(), pw->pw_name, NULL, 0,
287 NULL, password) == SIASUCCESS)
288 #else /* !USE_PAM && !HAVE_OSF_SIA */
289 auth_password(pw, password) == 1)
292 memset(password, 0, len);
294 return authenticated;
297 ssh2_auth_pubkey(struct passwd *pw, char *service)
301 char *pkalg, *pkblob, *sig;
302 unsigned int alen, blen, slen;
304 int authenticated = 0;
306 if (options.dsa_authentication == 0) {
307 debug("pubkey auth disabled");
310 have_sig = packet_get_char();
311 pkalg = packet_get_string(&alen);
312 if (strcmp(pkalg, KEX_DSS) != 0) {
314 log("bad pkalg %s", pkalg); /*XXX*/
317 pkblob = packet_get_string(&blen);
318 key = dsa_key_from_blob(pkblob, blen);
321 sig = packet_get_string(&slen);
324 if (datafellows & SSH_COMPAT_SESSIONID_ENCODING) {
325 buffer_put_string(&b, session_id2, session_id2_len);
327 buffer_append(&b, session_id2, session_id2_len);
329 /* reconstruct packet */
330 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
331 buffer_put_cstring(&b, pw->pw_name);
332 buffer_put_cstring(&b,
333 datafellows & SSH_BUG_PUBKEYAUTH ?
336 buffer_put_cstring(&b, "publickey");
337 buffer_put_char(&b, have_sig);
338 buffer_put_cstring(&b, KEX_DSS);
339 buffer_put_string(&b, pkblob, blen);
343 /* test for correct signature */
344 if (user_dsa_key_allowed(pw, key) &&
345 dsa_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1)
351 debug("test key...");
352 /* test whether pkalg/pkblob are acceptable */
353 /* XXX fake reply and always send PK_OK ? */
355 * XXX this allows testing whether a user is allowed
356 * to login: if you happen to have a valid pubkey this
357 * message is sent. the message is NEVER sent at all
358 * if a user is not allowed to login. is this an
361 if (user_dsa_key_allowed(pw, key)) {
362 packet_start(SSH2_MSG_USERAUTH_PK_OK);
363 packet_put_string(pkalg, alen);
364 packet_put_string(pkblob, blen);
374 return authenticated;
377 /* set and get current user */
382 return (authctxt != NULL && authctxt->valid) ? &authctxt->pw : NULL;
386 auth_set_user(char *u, char *s)
388 struct passwd *pw, *copy;
390 if (authctxt == NULL) {
391 authctxt = xmalloc(sizeof(*authctxt));
393 authctxt->user = xstrdup(u);
394 authctxt->service = xstrdup(s);
395 setproctitle("%s", u);
397 if (!pw || !allowed_user(pw)) {
398 log("auth_set_user: illegal user %s", u);
404 copy = &authctxt->pw;
405 memset(copy, 0, sizeof(*copy));
406 copy->pw_name = xstrdup(pw->pw_name);
407 copy->pw_passwd = xstrdup(pw->pw_passwd);
408 copy->pw_uid = pw->pw_uid;
409 copy->pw_gid = pw->pw_gid;
410 #ifdef HAVE_PW_CLASS_IN_PASSWD
411 copy->pw_class = xstrdup(pw->pw_class);
413 copy->pw_dir = xstrdup(pw->pw_dir);
414 copy->pw_shell = xstrdup(pw->pw_shell);
417 if (strcmp(u, authctxt->user) != 0 ||
418 strcmp(s, authctxt->service) != 0) {
419 log("auth_set_user: missmatch: (%s,%s)!=(%s,%s)",
420 u, s, authctxt->user, authctxt->service);
424 return auth_get_user();
427 /* return 1 if user allows given key */
429 user_dsa_key_allowed(struct passwd *pw, Key *key)
431 char line[8192], file[1024];
433 unsigned int bits = -1;
435 unsigned long linenum = 0;
439 /* Temporarily use the user's uid. */
440 temporarily_use_uid(pw->pw_uid);
442 /* The authorized keys. */
443 snprintf(file, sizeof file, "%.500s/%.100s", pw->pw_dir,
444 SSH_USER_PERMITTED_KEYS2);
446 /* Fail quietly if file does not exist */
447 if (stat(file, &st) < 0) {
448 /* Restore the privileged uid. */
452 /* Open the file containing the authorized keys. */
453 f = fopen(file, "r");
455 /* Restore the privileged uid. */
459 if (options.strict_modes) {
462 /* Check open file in order to avoid open/stat races */
463 if (fstat(fileno(f), &st) < 0 ||
464 (st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
465 (st.st_mode & 022) != 0) {
466 snprintf(buf, sizeof buf, "DSA authentication refused for %.100s: "
467 "bad ownership or modes for '%s'.", pw->pw_name, file);
470 /* Check path to SSH_USER_PERMITTED_KEYS */
472 static const char *check[] = {
473 "", SSH_USER_DIR, NULL
475 for (i = 0; check[i]; i++) {
476 snprintf(line, sizeof line, "%.500s/%.100s",
477 pw->pw_dir, check[i]);
478 if (stat(line, &st) < 0 ||
479 (st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
480 (st.st_mode & 022) != 0) {
481 snprintf(buf, sizeof buf,
482 "DSA authentication refused for %.100s: "
483 "bad ownership or modes for '%s'.",
498 found = key_new(KEY_DSA);
500 while (fgets(line, sizeof(line), f)) {
501 char *cp, *options = NULL;
503 /* Skip leading whitespace, empty and comment lines. */
504 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
506 if (!*cp || *cp == '\n' || *cp == '#')
509 bits = key_read(found, &cp);
511 /* no key? check if there are options for this key */
514 for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
515 if (*cp == '\\' && cp[1] == '"')
516 cp++; /* Skip both */
520 /* Skip remaining whitespace. */
521 for (; *cp == ' ' || *cp == '\t'; cp++)
523 bits = key_read(found, &cp);
525 /* still no key? advance to next line*/
529 if (key_equal(found, key) &&
530 auth_parse_options(pw, options, linenum) == 1) {
532 debug("matching key found: file %s, line %ld",