1 /* 2 * Copyright (c) 2000 Markus Friedl. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 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. 12 * 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. 23 */ 24 25 #include "includes.h" 26 RCSID("$OpenBSD: auth2.c,v 1.95 2002/08/22 21:33:58 markus Exp $"); 27 RCSID("$FreeBSD: src/crypto/openssh/auth2.c,v 1.2.2.9 2003/02/03 17:31:06 des Exp $"); 28 RCSID("$DragonFly: src/crypto/openssh/Attic/auth2.c,v 1.2 2003/06/17 04:24:36 dillon Exp $"); 29 30 #include "canohost.h" 31 #include "ssh2.h" 32 #include "xmalloc.h" 33 #include "packet.h" 34 #include "log.h" 35 #include "servconf.h" 36 #include "compat.h" 37 #include "auth.h" 38 #include "dispatch.h" 39 #include "pathnames.h" 40 #include "monitor_wrap.h" 41 42 /* import */ 43 extern ServerOptions options; 44 extern u_char *session_id2; 45 extern int session_id2_len; 46 47 Authctxt *x_authctxt = NULL; 48 49 /* methods */ 50 51 extern Authmethod method_none; 52 extern Authmethod method_pubkey; 53 extern Authmethod method_passwd; 54 extern Authmethod method_kbdint; 55 extern Authmethod method_hostbased; 56 57 Authmethod *authmethods[] = { 58 &method_none, 59 &method_pubkey, 60 &method_passwd, 61 &method_kbdint, 62 &method_hostbased, 63 NULL 64 }; 65 66 /* protocol */ 67 68 static void input_service_request(int, u_int32_t, void *); 69 static void input_userauth_request(int, u_int32_t, void *); 70 71 /* helper */ 72 static Authmethod *authmethod_lookup(const char *); 73 static char *authmethods_get(void); 74 int user_key_allowed(struct passwd *, Key *); 75 int hostbased_key_allowed(struct passwd *, const char *, char *, Key *); 76 77 /* 78 * loop until authctxt->success == TRUE 79 */ 80 81 Authctxt * 82 do_authentication2(void) 83 { 84 Authctxt *authctxt = authctxt_new(); 85 86 x_authctxt = authctxt; /*XXX*/ 87 88 /* challenge-response is implemented via keyboard interactive */ 89 if (options.challenge_response_authentication) 90 options.kbd_interactive_authentication = 1; 91 if (options.pam_authentication_via_kbd_int) 92 options.kbd_interactive_authentication = 1; 93 if (use_privsep) 94 options.pam_authentication_via_kbd_int = 0; 95 96 dispatch_init(&dispatch_protocol_error); 97 dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); 98 dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); 99 100 return (authctxt); 101 } 102 103 static void 104 input_service_request(int type, u_int32_t seq, void *ctxt) 105 { 106 Authctxt *authctxt = ctxt; 107 u_int len; 108 int acceptit = 0; 109 char *service = packet_get_string(&len); 110 packet_check_eom(); 111 112 if (authctxt == NULL) 113 fatal("input_service_request: no authctxt"); 114 115 if (strcmp(service, "ssh-userauth") == 0) { 116 if (!authctxt->success) { 117 acceptit = 1; 118 /* now we can handle user-auth requests */ 119 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); 120 } 121 } 122 /* XXX all other service requests are denied */ 123 124 if (acceptit) { 125 packet_start(SSH2_MSG_SERVICE_ACCEPT); 126 packet_put_cstring(service); 127 packet_send(); 128 packet_write_wait(); 129 } else { 130 debug("bad service request %s", service); 131 packet_disconnect("bad service request %s", service); 132 } 133 xfree(service); 134 } 135 136 static void 137 input_userauth_request(int type, u_int32_t seq, void *ctxt) 138 { 139 Authctxt *authctxt = ctxt; 140 Authmethod *m = NULL; 141 char *user, *service, *method, *style = NULL; 142 int authenticated = 0; 143 #ifdef HAVE_LOGIN_CAP 144 login_cap_t *lc; 145 const char *from_host, *from_ip; 146 147 from_host = get_canonical_hostname(options.verify_reverse_mapping); 148 from_ip = get_remote_ipaddr(); 149 #endif 150 151 if (authctxt == NULL) 152 fatal("input_userauth_request: no authctxt"); 153 154 user = packet_get_string(NULL); 155 service = packet_get_string(NULL); 156 method = packet_get_string(NULL); 157 debug("userauth-request for user %s service %s method %s", user, service, method); 158 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 159 160 if ((style = strchr(user, ':')) != NULL) 161 *style++ = 0; 162 163 if (authctxt->attempt++ == 0) { 164 /* setup auth context */ 165 authctxt->pw = PRIVSEP(getpwnamallow(user)); 166 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 167 authctxt->valid = 1; 168 debug2("input_userauth_request: setting up authctxt for %s", user); 169 #ifdef USE_PAM 170 PRIVSEP(start_pam(authctxt->pw->pw_name)); 171 #endif 172 } else { 173 log("input_userauth_request: illegal user %s", user); 174 #ifdef USE_PAM 175 PRIVSEP(start_pam("NOUSER")); 176 #endif 177 } 178 setproctitle("%s%s", authctxt->pw ? user : "unknown", 179 use_privsep ? " [net]" : ""); 180 authctxt->user = xstrdup(user); 181 authctxt->service = xstrdup(service); 182 authctxt->style = style ? xstrdup(style) : NULL; 183 if (use_privsep) 184 mm_inform_authserv(service, style); 185 } else if (strcmp(user, authctxt->user) != 0 || 186 strcmp(service, authctxt->service) != 0) { 187 packet_disconnect("Change of username or service not allowed: " 188 "(%s,%s) -> (%s,%s)", 189 authctxt->user, authctxt->service, user, service); 190 } 191 192 #ifdef HAVE_LOGIN_CAP 193 if (authctxt->pw != NULL) { 194 lc = login_getpwclass(authctxt->pw); 195 if (lc == NULL) 196 lc = login_getclassbyname(NULL, authctxt->pw); 197 if (!auth_hostok(lc, from_host, from_ip)) { 198 log("Denied connection for %.200s from %.200s [%.200s].", 199 authctxt->pw->pw_name, from_host, from_ip); 200 packet_disconnect("Sorry, you are not allowed to connect."); 201 } 202 if (!auth_timeok(lc, time(NULL))) { 203 log("LOGIN %.200s REFUSED (TIME) FROM %.200s", 204 authctxt->pw->pw_name, from_host); 205 packet_disconnect("Logins not available right now."); 206 } 207 login_close(lc); 208 lc = NULL; 209 } 210 #endif /* HAVE_LOGIN_CAP */ 211 212 /* reset state */ 213 auth2_challenge_stop(authctxt); 214 authctxt->postponed = 0; 215 216 /* try to authenticate user */ 217 m = authmethod_lookup(method); 218 if (m != NULL) { 219 debug2("input_userauth_request: try method %s", method); 220 authenticated = m->userauth(authctxt); 221 } 222 userauth_finish(authctxt, authenticated, method); 223 224 xfree(service); 225 xfree(user); 226 xfree(method); 227 } 228 229 void 230 userauth_finish(Authctxt *authctxt, int authenticated, char *method) 231 { 232 char *methods; 233 234 if (!authctxt->valid && authenticated) 235 fatal("INTERNAL ERROR: authenticated invalid user %s", 236 authctxt->user); 237 238 /* Special handling for root */ 239 if (!use_privsep && 240 authenticated && authctxt->pw->pw_uid == 0 && 241 !auth_root_allowed(method)) 242 authenticated = 0; 243 244 #ifdef USE_PAM 245 if (!use_privsep && authenticated && authctxt->user && 246 !do_pam_account(authctxt->user, NULL)) 247 authenticated = 0; 248 #endif /* USE_PAM */ 249 250 #ifdef _UNICOS 251 if (authenticated && cray_access_denied(authctxt->user)) { 252 authenticated = 0; 253 fatal("Access denied for user %s.",authctxt->user); 254 } 255 #endif /* _UNICOS */ 256 257 /* Log before sending the reply */ 258 auth_log(authctxt, authenticated, method, " ssh2"); 259 260 if (authctxt->postponed) 261 return; 262 263 /* XXX todo: check if multiple auth methods are needed */ 264 if (authenticated == 1) { 265 /* turn off userauth */ 266 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); 267 packet_start(SSH2_MSG_USERAUTH_SUCCESS); 268 packet_send(); 269 packet_write_wait(); 270 /* now we can break out */ 271 authctxt->success = 1; 272 } else { 273 if (authctxt->failures++ > AUTH_FAIL_MAX) { 274 packet_disconnect(AUTH_FAIL_MSG, authctxt->user); 275 } 276 #ifdef _UNICOS 277 if (strcmp(method, "password") == 0) 278 cray_login_failure(authctxt->user, IA_UDBERR); 279 #endif /* _UNICOS */ 280 methods = authmethods_get(); 281 packet_start(SSH2_MSG_USERAUTH_FAILURE); 282 packet_put_cstring(methods); 283 packet_put_char(0); /* XXX partial success, unused */ 284 packet_send(); 285 packet_write_wait(); 286 xfree(methods); 287 } 288 } 289 290 /* get current user */ 291 292 struct passwd* 293 auth_get_user(void) 294 { 295 return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL; 296 } 297 298 #define DELIM "," 299 300 static char * 301 authmethods_get(void) 302 { 303 Buffer b; 304 char *list; 305 int i; 306 307 buffer_init(&b); 308 for (i = 0; authmethods[i] != NULL; i++) { 309 if (strcmp(authmethods[i]->name, "none") == 0) 310 continue; 311 if (authmethods[i]->enabled != NULL && 312 *(authmethods[i]->enabled) != 0) { 313 if (buffer_len(&b) > 0) 314 buffer_append(&b, ",", 1); 315 buffer_append(&b, authmethods[i]->name, 316 strlen(authmethods[i]->name)); 317 } 318 } 319 buffer_append(&b, "\0", 1); 320 list = xstrdup(buffer_ptr(&b)); 321 buffer_free(&b); 322 return list; 323 } 324 325 static Authmethod * 326 authmethod_lookup(const char *name) 327 { 328 int i; 329 330 if (name != NULL) 331 for (i = 0; authmethods[i] != NULL; i++) 332 if (authmethods[i]->enabled != NULL && 333 *(authmethods[i]->enabled) != 0 && 334 strcmp(name, authmethods[i]->name) == 0) 335 return authmethods[i]; 336 debug2("Unrecognized authentication method name: %s", 337 name ? name : "NULL"); 338 return NULL; 339 } 340