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$"); 28 29 #include "canohost.h" 30 #include "ssh2.h" 31 #include "xmalloc.h" 32 #include "packet.h" 33 #include "log.h" 34 #include "servconf.h" 35 #include "compat.h" 36 #include "auth.h" 37 #include "dispatch.h" 38 #include "pathnames.h" 39 #include "monitor_wrap.h" 40 41 /* import */ 42 extern ServerOptions options; 43 extern u_char *session_id2; 44 extern int session_id2_len; 45 46 Authctxt *x_authctxt = NULL; 47 48 /* methods */ 49 50 extern Authmethod method_none; 51 extern Authmethod method_pubkey; 52 extern Authmethod method_passwd; 53 extern Authmethod method_kbdint; 54 extern Authmethod method_hostbased; 55 56 Authmethod *authmethods[] = { 57 &method_none, 58 &method_pubkey, 59 &method_passwd, 60 &method_kbdint, 61 &method_hostbased, 62 NULL 63 }; 64 65 /* protocol */ 66 67 static void input_service_request(int, u_int32_t, void *); 68 static void input_userauth_request(int, u_int32_t, void *); 69 70 /* helper */ 71 static Authmethod *authmethod_lookup(const char *); 72 static char *authmethods_get(void); 73 int user_key_allowed(struct passwd *, Key *); 74 int hostbased_key_allowed(struct passwd *, const char *, char *, Key *); 75 76 /* 77 * loop until authctxt->success == TRUE 78 */ 79 80 Authctxt * 81 do_authentication2(void) 82 { 83 Authctxt *authctxt = authctxt_new(); 84 85 x_authctxt = authctxt; /*XXX*/ 86 87 /* challenge-response is implemented via keyboard interactive */ 88 if (options.challenge_response_authentication) 89 options.kbd_interactive_authentication = 1; 90 if (options.pam_authentication_via_kbd_int) 91 options.kbd_interactive_authentication = 1; 92 if (use_privsep) 93 options.pam_authentication_via_kbd_int = 0; 94 95 dispatch_init(&dispatch_protocol_error); 96 dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); 97 dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); 98 99 return (authctxt); 100 } 101 102 static void 103 input_service_request(int type, u_int32_t seq, void *ctxt) 104 { 105 Authctxt *authctxt = ctxt; 106 u_int len; 107 int acceptit = 0; 108 char *service = packet_get_string(&len); 109 packet_check_eom(); 110 111 if (authctxt == NULL) 112 fatal("input_service_request: no authctxt"); 113 114 if (strcmp(service, "ssh-userauth") == 0) { 115 if (!authctxt->success) { 116 acceptit = 1; 117 /* now we can handle user-auth requests */ 118 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); 119 } 120 } 121 /* XXX all other service requests are denied */ 122 123 if (acceptit) { 124 packet_start(SSH2_MSG_SERVICE_ACCEPT); 125 packet_put_cstring(service); 126 packet_send(); 127 packet_write_wait(); 128 } else { 129 debug("bad service request %s", service); 130 packet_disconnect("bad service request %s", service); 131 } 132 xfree(service); 133 } 134 135 static void 136 input_userauth_request(int type, u_int32_t seq, void *ctxt) 137 { 138 Authctxt *authctxt = ctxt; 139 Authmethod *m = NULL; 140 char *user, *service, *method, *style = NULL; 141 int authenticated = 0; 142 #ifdef HAVE_LOGIN_CAP 143 login_cap_t *lc; 144 const char *from_host, *from_ip; 145 146 from_host = get_canonical_hostname(options.verify_reverse_mapping); 147 from_ip = get_remote_ipaddr(); 148 #endif 149 150 if (authctxt == NULL) 151 fatal("input_userauth_request: no authctxt"); 152 153 user = packet_get_string(NULL); 154 service = packet_get_string(NULL); 155 method = packet_get_string(NULL); 156 debug("userauth-request for user %s service %s method %s", user, service, method); 157 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 158 159 if ((style = strchr(user, ':')) != NULL) 160 *style++ = 0; 161 162 if (authctxt->attempt++ == 0) { 163 /* setup auth context */ 164 authctxt->pw = PRIVSEP(getpwnamallow(user)); 165 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 166 authctxt->valid = 1; 167 debug2("input_userauth_request: setting up authctxt for %s", user); 168 #ifdef USE_PAM 169 PRIVSEP(start_pam(authctxt->pw->pw_name)); 170 #endif 171 } else { 172 log("input_userauth_request: illegal user %s", user); 173 #ifdef USE_PAM 174 PRIVSEP(start_pam("NOUSER")); 175 #endif 176 } 177 setproctitle("%s%s", authctxt->pw ? user : "unknown", 178 use_privsep ? " [net]" : ""); 179 authctxt->user = xstrdup(user); 180 authctxt->service = xstrdup(service); 181 authctxt->style = style ? xstrdup(style) : NULL; 182 if (use_privsep) 183 mm_inform_authserv(service, style); 184 } else if (strcmp(user, authctxt->user) != 0 || 185 strcmp(service, authctxt->service) != 0) { 186 packet_disconnect("Change of username or service not allowed: " 187 "(%s,%s) -> (%s,%s)", 188 authctxt->user, authctxt->service, user, service); 189 } 190 191 #ifdef HAVE_LOGIN_CAP 192 if (authctxt->pw != NULL) { 193 lc = login_getpwclass(authctxt->pw); 194 if (lc == NULL) 195 lc = login_getclassbyname(NULL, authctxt->pw); 196 if (!auth_hostok(lc, from_host, from_ip)) { 197 log("Denied connection for %.200s from %.200s [%.200s].", 198 authctxt->pw->pw_name, from_host, from_ip); 199 packet_disconnect("Sorry, you are not allowed to connect."); 200 } 201 if (!auth_timeok(lc, time(NULL))) { 202 log("LOGIN %.200s REFUSED (TIME) FROM %.200s", 203 authctxt->pw->pw_name, from_host); 204 packet_disconnect("Logins not available right now."); 205 } 206 login_close(lc); 207 lc = NULL; 208 } 209 #endif /* HAVE_LOGIN_CAP */ 210 211 /* reset state */ 212 auth2_challenge_stop(authctxt); 213 authctxt->postponed = 0; 214 215 /* try to authenticate user */ 216 m = authmethod_lookup(method); 217 if (m != NULL) { 218 debug2("input_userauth_request: try method %s", method); 219 authenticated = m->userauth(authctxt); 220 } 221 userauth_finish(authctxt, authenticated, method); 222 223 xfree(service); 224 xfree(user); 225 xfree(method); 226 } 227 228 void 229 userauth_finish(Authctxt *authctxt, int authenticated, char *method) 230 { 231 char *methods; 232 233 if (!authctxt->valid && authenticated) 234 fatal("INTERNAL ERROR: authenticated invalid user %s", 235 authctxt->user); 236 237 /* Special handling for root */ 238 if (!use_privsep && 239 authenticated && authctxt->pw->pw_uid == 0 && 240 !auth_root_allowed(method)) 241 authenticated = 0; 242 243 #ifdef USE_PAM 244 if (!use_privsep && authenticated && authctxt->user && 245 !do_pam_account(authctxt->user, NULL)) 246 authenticated = 0; 247 #endif /* USE_PAM */ 248 249 #ifdef _UNICOS 250 if (authenticated && cray_access_denied(authctxt->user)) { 251 authenticated = 0; 252 fatal("Access denied for user %s.",authctxt->user); 253 } 254 #endif /* _UNICOS */ 255 256 /* Log before sending the reply */ 257 auth_log(authctxt, authenticated, method, " ssh2"); 258 259 if (authctxt->postponed) 260 return; 261 262 /* XXX todo: check if multiple auth methods are needed */ 263 if (authenticated == 1) { 264 /* turn off userauth */ 265 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); 266 packet_start(SSH2_MSG_USERAUTH_SUCCESS); 267 packet_send(); 268 packet_write_wait(); 269 /* now we can break out */ 270 authctxt->success = 1; 271 } else { 272 if (authctxt->failures++ > AUTH_FAIL_MAX) { 273 packet_disconnect(AUTH_FAIL_MSG, authctxt->user); 274 } 275 #ifdef _UNICOS 276 if (strcmp(method, "password") == 0) 277 cray_login_failure(authctxt->user, IA_UDBERR); 278 #endif /* _UNICOS */ 279 methods = authmethods_get(); 280 packet_start(SSH2_MSG_USERAUTH_FAILURE); 281 packet_put_cstring(methods); 282 packet_put_char(0); /* XXX partial success, unused */ 283 packet_send(); 284 packet_write_wait(); 285 xfree(methods); 286 } 287 } 288 289 /* get current user */ 290 291 struct passwd* 292 auth_get_user(void) 293 { 294 return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL; 295 } 296 297 #define DELIM "," 298 299 static char * 300 authmethods_get(void) 301 { 302 Buffer b; 303 char *list; 304 int i; 305 306 buffer_init(&b); 307 for (i = 0; authmethods[i] != NULL; i++) { 308 if (strcmp(authmethods[i]->name, "none") == 0) 309 continue; 310 if (authmethods[i]->enabled != NULL && 311 *(authmethods[i]->enabled) != 0) { 312 if (buffer_len(&b) > 0) 313 buffer_append(&b, ",", 1); 314 buffer_append(&b, authmethods[i]->name, 315 strlen(authmethods[i]->name)); 316 } 317 } 318 buffer_append(&b, "\0", 1); 319 list = xstrdup(buffer_ptr(&b)); 320 buffer_free(&b); 321 return list; 322 } 323 324 static Authmethod * 325 authmethod_lookup(const char *name) 326 { 327 int i; 328 329 if (name != NULL) 330 for (i = 0; authmethods[i] != NULL; i++) 331 if (authmethods[i]->enabled != NULL && 332 *(authmethods[i]->enabled) != 0 && 333 strcmp(name, authmethods[i]->name) == 0) 334 return authmethods[i]; 335 debug2("Unrecognized authentication method name: %s", 336 name ? name : "NULL"); 337 return NULL; 338 } 339