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 1.93 2002/05/31 11:35:15 markus Exp $"); 27 RCSID("$FreeBSD$"); 28 29 #include "ssh2.h" 30 #include "xmalloc.h" 31 #include "packet.h" 32 #include "log.h" 33 #include "servconf.h" 34 #include "compat.h" 35 #include "auth.h" 36 #include "dispatch.h" 37 #include "pathnames.h" 38 #include "monitor_wrap.h" 39 40 /* import */ 41 extern ServerOptions options; 42 extern u_char *session_id2; 43 extern int session_id2_len; 44 45 Authctxt *x_authctxt = NULL; 46 47 /* methods */ 48 49 extern Authmethod method_none; 50 extern Authmethod method_pubkey; 51 extern Authmethod method_passwd; 52 extern Authmethod method_kbdint; 53 extern Authmethod method_hostbased; 54 55 Authmethod *authmethods[] = { 56 &method_none, 57 &method_pubkey, 58 &method_passwd, 59 &method_kbdint, 60 &method_hostbased, 61 NULL 62 }; 63 64 /* protocol */ 65 66 static void input_service_request(int, u_int32_t, void *); 67 static void input_userauth_request(int, u_int32_t, void *); 68 69 /* helper */ 70 static Authmethod *authmethod_lookup(const char *); 71 static char *authmethods_get(void); 72 int user_key_allowed(struct passwd *, Key *); 73 int hostbased_key_allowed(struct passwd *, const char *, char *, Key *); 74 75 /* 76 * loop until authctxt->success == TRUE 77 */ 78 79 Authctxt * 80 do_authentication2(void) 81 { 82 Authctxt *authctxt = authctxt_new(); 83 84 x_authctxt = authctxt; /*XXX*/ 85 86 /* challenge-response is implemented via keyboard interactive */ 87 if (options.challenge_response_authentication) 88 options.kbd_interactive_authentication = 1; 89 if (options.pam_authentication_via_kbd_int) 90 options.kbd_interactive_authentication = 1; 91 if (use_privsep) 92 options.pam_authentication_via_kbd_int = 0; 93 94 dispatch_init(&dispatch_protocol_error); 95 dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); 96 dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); 97 98 return (authctxt); 99 } 100 101 static void 102 input_service_request(int type, u_int32_t seq, void *ctxt) 103 { 104 Authctxt *authctxt = ctxt; 105 u_int len; 106 int accept = 0; 107 char *service = packet_get_string(&len); 108 packet_check_eom(); 109 110 if (authctxt == NULL) 111 fatal("input_service_request: no authctxt"); 112 113 if (strcmp(service, "ssh-userauth") == 0) { 114 if (!authctxt->success) { 115 accept = 1; 116 /* now we can handle user-auth requests */ 117 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); 118 } 119 } 120 /* XXX all other service requests are denied */ 121 122 if (accept) { 123 packet_start(SSH2_MSG_SERVICE_ACCEPT); 124 packet_put_cstring(service); 125 packet_send(); 126 packet_write_wait(); 127 } else { 128 debug("bad service request %s", service); 129 packet_disconnect("bad service request %s", service); 130 } 131 xfree(service); 132 } 133 134 static void 135 input_userauth_request(int type, u_int32_t seq, void *ctxt) 136 { 137 Authctxt *authctxt = ctxt; 138 Authmethod *m = NULL; 139 char *user, *service, *method, *style = NULL; 140 int authenticated = 0; 141 #ifdef HAVE_LOGIN_CAP 142 login_cap_t *lc; 143 const char *from_host, *from_ip; 144 145 from_host = get_canonical_hostname(options.verify_reverse_mapping); 146 from_ip = get_remote_ipaddr(); 147 #endif 148 149 if (authctxt == NULL) 150 fatal("input_userauth_request: no authctxt"); 151 152 user = packet_get_string(NULL); 153 service = packet_get_string(NULL); 154 method = packet_get_string(NULL); 155 debug("userauth-request for user %s service %s method %s", user, service, method); 156 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 157 158 if ((style = strchr(user, ':')) != NULL) 159 *style++ = 0; 160 161 if (authctxt->attempt++ == 0) { 162 /* setup auth context */ 163 authctxt->pw = PRIVSEP(getpwnamallow(user)); 164 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 165 authctxt->valid = 1; 166 debug2("input_userauth_request: setting up authctxt for %s", user); 167 #ifdef USE_PAM 168 PRIVSEP(start_pam(authctxt->pw->pw_name)); 169 #endif 170 } else { 171 log("input_userauth_request: illegal user %s", user); 172 #ifdef USE_PAM 173 PRIVSEP(start_pam("NOUSER")); 174 #endif 175 } 176 setproctitle("%s%s", authctxt->pw ? user : "unknown", 177 use_privsep ? " [net]" : ""); 178 authctxt->user = xstrdup(user); 179 authctxt->service = xstrdup(service); 180 authctxt->style = style ? xstrdup(style) : NULL; 181 if (use_privsep) 182 mm_inform_authserv(service, style); 183 } else if (strcmp(user, authctxt->user) != 0 || 184 strcmp(service, authctxt->service) != 0) { 185 packet_disconnect("Change of username or service not allowed: " 186 "(%s,%s) -> (%s,%s)", 187 authctxt->user, authctxt->service, user, service); 188 } 189 190 #ifdef HAVE_LOGIN_CAP 191 if (authctxt->pw != NULL) { 192 lc = login_getpwclass(authctxt->pw); 193 if (lc == NULL) 194 lc = login_getclassbyname(NULL, authctxt->pw); 195 if (!auth_hostok(lc, from_host, from_ip)) { 196 log("Denied connection for %.200s from %.200s [%.200s].", 197 authctxt->pw->pw_name, from_host, from_ip); 198 packet_disconnect("Sorry, you are not allowed to connect."); 199 } 200 if (!auth_timeok(lc, time(NULL))) { 201 log("LOGIN %.200s REFUSED (TIME) FROM %.200s", 202 authctxt->pw->pw_name, from_host); 203 packet_disconnect("Logins not available right now."); 204 } 205 login_close(lc); 206 lc = NULL; 207 } 208 #endif /* HAVE_LOGIN_CAP */ 209 210 /* reset state */ 211 auth2_challenge_stop(authctxt); 212 authctxt->postponed = 0; 213 214 /* try to authenticate user */ 215 m = authmethod_lookup(method); 216 if (m != NULL) { 217 debug2("input_userauth_request: try method %s", method); 218 authenticated = m->userauth(authctxt); 219 } 220 userauth_finish(authctxt, authenticated, method); 221 222 xfree(service); 223 xfree(user); 224 xfree(method); 225 } 226 227 void 228 userauth_finish(Authctxt *authctxt, int authenticated, char *method) 229 { 230 char *methods; 231 232 if (!authctxt->valid && authenticated) 233 fatal("INTERNAL ERROR: authenticated invalid user %s", 234 authctxt->user); 235 236 /* Special handling for root */ 237 if (authenticated && authctxt->pw->pw_uid == 0 && 238 !auth_root_allowed(method)) 239 authenticated = 0; 240 241 #ifdef USE_PAM 242 if (!use_privsep && authenticated && authctxt->user && 243 !do_pam_account(authctxt->user, NULL)) 244 authenticated = 0; 245 #endif /* USE_PAM */ 246 247 /* Log before sending the reply */ 248 auth_log(authctxt, authenticated, method, " ssh2"); 249 250 if (authctxt->postponed) 251 return; 252 253 /* XXX todo: check if multiple auth methods are needed */ 254 if (authenticated == 1) { 255 /* turn off userauth */ 256 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); 257 packet_start(SSH2_MSG_USERAUTH_SUCCESS); 258 packet_send(); 259 packet_write_wait(); 260 /* now we can break out */ 261 authctxt->success = 1; 262 } else { 263 if (authctxt->failures++ > AUTH_FAIL_MAX) { 264 #ifdef WITH_AIXAUTHENTICATE 265 /* XXX: privsep */ 266 loginfailed(authctxt->user, 267 get_canonical_hostname(options.verify_reverse_mapping), 268 "ssh"); 269 #endif /* WITH_AIXAUTHENTICATE */ 270 packet_disconnect(AUTH_FAIL_MSG, authctxt->user); 271 } 272 methods = authmethods_get(); 273 packet_start(SSH2_MSG_USERAUTH_FAILURE); 274 packet_put_cstring(methods); 275 packet_put_char(0); /* XXX partial success, unused */ 276 packet_send(); 277 packet_write_wait(); 278 xfree(methods); 279 } 280 } 281 282 /* get current user */ 283 284 struct passwd* 285 auth_get_user(void) 286 { 287 return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL; 288 } 289 290 #define DELIM "," 291 292 static char * 293 authmethods_get(void) 294 { 295 Buffer b; 296 char *list; 297 int i; 298 299 buffer_init(&b); 300 for (i = 0; authmethods[i] != NULL; i++) { 301 if (strcmp(authmethods[i]->name, "none") == 0) 302 continue; 303 if (authmethods[i]->enabled != NULL && 304 *(authmethods[i]->enabled) != 0) { 305 if (buffer_len(&b) > 0) 306 buffer_append(&b, ",", 1); 307 buffer_append(&b, authmethods[i]->name, 308 strlen(authmethods[i]->name)); 309 } 310 } 311 buffer_append(&b, "\0", 1); 312 list = xstrdup(buffer_ptr(&b)); 313 buffer_free(&b); 314 return list; 315 } 316 317 static Authmethod * 318 authmethod_lookup(const char *name) 319 { 320 int i; 321 322 if (name != NULL) 323 for (i = 0; authmethods[i] != NULL; i++) 324 if (authmethods[i]->enabled != NULL && 325 *(authmethods[i]->enabled) != 0 && 326 strcmp(name, authmethods[i]->name) == 0) 327 return authmethods[i]; 328 debug2("Unrecognized authentication method name: %s", 329 name ? name : "NULL"); 330 return NULL; 331 } 332