1 /* $NetBSD: smtp_sasl_glue.c,v 1.1.1.2 2013/01/02 18:59:08 tron Exp $ */ 2 3 /*++ 4 /* NAME 5 /* smtp_sasl_glue 3 6 /* SUMMARY 7 /* Postfix SASL interface for SMTP client 8 /* SYNOPSIS 9 /* #include smtp_sasl.h 10 /* 11 /* void smtp_sasl_initialize() 12 /* 13 /* void smtp_sasl_connect(session) 14 /* SMTP_SESSION *session; 15 /* 16 /* void smtp_sasl_start(session, sasl_opts_name, sasl_opts_val) 17 /* SMTP_SESSION *session; 18 /* 19 /* int smtp_sasl_passwd_lookup(session) 20 /* SMTP_SESSION *session; 21 /* 22 /* int smtp_sasl_authenticate(session, why) 23 /* SMTP_SESSION *session; 24 /* DSN_BUF *why; 25 /* 26 /* void smtp_sasl_cleanup(session) 27 /* SMTP_SESSION *session; 28 /* 29 /* void smtp_sasl_passivate(session, buf) 30 /* SMTP_SESSION *session; 31 /* VSTRING *buf; 32 /* 33 /* int smtp_sasl_activate(session, buf) 34 /* SMTP_SESSION *session; 35 /* char *buf; 36 /* DESCRIPTION 37 /* smtp_sasl_initialize() initializes the SASL library. This 38 /* routine must be called once at process startup, before any 39 /* chroot operations. 40 /* 41 /* smtp_sasl_connect() performs per-session initialization. This 42 /* routine must be called once at the start of each connection. 43 /* 44 /* smtp_sasl_start() performs per-session initialization. This 45 /* routine must be called once per session before doing any SASL 46 /* authentication. The sasl_opts_name and sasl_opts_val parameters are 47 /* the postfix configuration parameters setting the security 48 /* policy of the SASL authentication. 49 /* 50 /* smtp_sasl_passwd_lookup() looks up the username/password 51 /* for the current SMTP server. The result is zero in case 52 /* of failure, a long jump in case of error. 53 /* 54 /* smtp_sasl_authenticate() implements the SASL authentication 55 /* dialog. The result is < 0 in case of protocol failure, zero in 56 /* case of unsuccessful authentication, > 0 in case of success. 57 /* The why argument is updated with a reason for failure. 58 /* This routine must be called only when smtp_sasl_passwd_lookup() 59 /* succeeds. 60 /* 61 /* smtp_sasl_cleanup() cleans up. It must be called at the 62 /* end of every SMTP session that uses SASL authentication. 63 /* This routine is a noop for non-SASL sessions. 64 /* 65 /* smtp_sasl_passivate() appends flattened SASL attributes to the 66 /* specified buffer. The SASL attributes are not destroyed. 67 /* 68 /* smtp_sasl_activate() restores SASL attributes from the 69 /* specified buffer. The buffer is modified. A result < 0 70 /* means there was an error. 71 /* 72 /* Arguments: 73 /* .IP session 74 /* Session context. 75 /* .IP mech_list 76 /* String of SASL mechanisms (separated by blanks) 77 /* DIAGNOSTICS 78 /* All errors are fatal. 79 /* LICENSE 80 /* .ad 81 /* .fi 82 /* The Secure Mailer license must be distributed with this software. 83 /* AUTHOR(S) 84 /* Original author: 85 /* Till Franke 86 /* SuSE Rhein/Main AG 87 /* 65760 Eschborn, Germany 88 /* 89 /* Adopted by: 90 /* Wietse Venema 91 /* IBM T.J. Watson Research 92 /* P.O. Box 704 93 /* Yorktown Heights, NY 10598, USA 94 /*--*/ 95 96 /* 97 * System library. 98 */ 99 #include <sys_defs.h> 100 #include <stdlib.h> 101 #include <string.h> 102 103 /* 104 * Utility library 105 */ 106 #include <msg.h> 107 #include <mymalloc.h> 108 #include <stringops.h> 109 #include <split_at.h> 110 111 /* 112 * Global library 113 */ 114 #include <mail_params.h> 115 #include <string_list.h> 116 #include <maps.h> 117 #include <mail_addr_find.h> 118 #include <smtp_stream.h> 119 120 /* 121 * XSASL library. 122 */ 123 #include <xsasl.h> 124 125 /* 126 * Application-specific 127 */ 128 #include "smtp.h" 129 #include "smtp_sasl.h" 130 #include "smtp_sasl_auth_cache.h" 131 132 #ifdef USE_SASL_AUTH 133 134 /* 135 * Per-host login/password information. 136 */ 137 static MAPS *smtp_sasl_passwd_map; 138 139 /* 140 * Supported SASL mechanisms. 141 */ 142 STRING_LIST *smtp_sasl_mechs; 143 144 /* 145 * SASL implementation handle. 146 */ 147 static XSASL_CLIENT_IMPL *smtp_sasl_impl; 148 149 /* 150 * The 535 SASL authentication failure cache. 151 */ 152 #ifdef HAVE_SASL_AUTH_CACHE 153 static SMTP_SASL_AUTH_CACHE *smtp_sasl_auth_cache; 154 155 #endif 156 157 /* smtp_sasl_passwd_lookup - password lookup routine */ 158 159 int smtp_sasl_passwd_lookup(SMTP_SESSION *session) 160 { 161 const char *myname = "smtp_sasl_passwd_lookup"; 162 SMTP_STATE *state = session->state; 163 const char *value; 164 char *passwd; 165 166 /* 167 * Sanity check. 168 */ 169 if (smtp_sasl_passwd_map == 0) 170 msg_panic("%s: passwd map not initialized", myname); 171 172 /* 173 * Look up the per-server password information. Try the hostname first, 174 * then try the destination. 175 * 176 * XXX Instead of using nexthop (the intended destination) we use dest 177 * (either the intended destination, or a fall-back destination). 178 * 179 * XXX SASL authentication currently depends on the host/domain but not on 180 * the TCP port. If the port is not :25, we should append it to the table 181 * lookup key. Code for this was briefly introduced into 2.2 snapshots, 182 * but didn't canonicalize the TCP port, and did not append the port to 183 * the MX hostname. 184 */ 185 smtp_sasl_passwd_map->error = 0; 186 if (((state->misc_flags & SMTP_MISC_FLAG_USE_LMTP) == 0 187 && var_smtp_sender_auth && state->request->sender[0] 188 && (value = mail_addr_find(smtp_sasl_passwd_map, 189 state->request->sender, (char **) 0)) != 0) 190 || (smtp_sasl_passwd_map->error == 0 191 && (value = maps_find(smtp_sasl_passwd_map, 192 session->host, 0)) != 0) 193 || (smtp_sasl_passwd_map->error == 0 194 && (value = maps_find(smtp_sasl_passwd_map, 195 session->dest, 0)) != 0)) { 196 if (session->sasl_username) 197 myfree(session->sasl_username); 198 session->sasl_username = mystrdup(value); 199 passwd = split_at(session->sasl_username, ':'); 200 if (session->sasl_passwd) 201 myfree(session->sasl_passwd); 202 session->sasl_passwd = mystrdup(passwd ? passwd : ""); 203 if (msg_verbose) 204 msg_info("%s: host `%s' user `%s' pass `%s'", 205 myname, session->host, 206 session->sasl_username, session->sasl_passwd); 207 return (1); 208 } else if (smtp_sasl_passwd_map->error) { 209 msg_warn("%s: %s lookup error", 210 state->request->queue_id, smtp_sasl_passwd_map->title); 211 vstream_longjmp(session->stream, SMTP_ERR_DATA); 212 } else { 213 if (msg_verbose) 214 msg_info("%s: no auth info found (sender=`%s', host=`%s')", 215 myname, state->request->sender, session->host); 216 return (0); 217 } 218 } 219 220 /* smtp_sasl_initialize - per-process initialization (pre jail) */ 221 222 void smtp_sasl_initialize(void) 223 { 224 225 /* 226 * Sanity check. 227 */ 228 if (smtp_sasl_passwd_map || smtp_sasl_impl) 229 msg_panic("smtp_sasl_initialize: repeated call"); 230 if (*var_smtp_sasl_passwd == 0) 231 msg_fatal("specify a password table via the `%s' configuration parameter", 232 VAR_SMTP_SASL_PASSWD); 233 234 /* 235 * Open the per-host password table and initialize the SASL library. Use 236 * shared locks for reading, just in case someone updates the table. 237 */ 238 smtp_sasl_passwd_map = maps_create("smtp_sasl_passwd", 239 var_smtp_sasl_passwd, 240 DICT_FLAG_LOCK | DICT_FLAG_FOLD_FIX); 241 if ((smtp_sasl_impl = xsasl_client_init(var_smtp_sasl_type, 242 var_smtp_sasl_path)) == 0) 243 msg_fatal("SASL library initialization"); 244 245 /* 246 * Initialize optional supported mechanism matchlist 247 */ 248 if (*var_smtp_sasl_mechs) 249 smtp_sasl_mechs = string_list_init(MATCH_FLAG_NONE, 250 var_smtp_sasl_mechs); 251 252 /* 253 * Initialize the 535 SASL authentication failure cache. 254 */ 255 if (*var_smtp_sasl_auth_cache_name) { 256 #ifdef HAVE_SASL_AUTH_CACHE 257 smtp_sasl_auth_cache = 258 smtp_sasl_auth_cache_init(var_smtp_sasl_auth_cache_name, 259 var_smtp_sasl_auth_cache_time); 260 #else 261 msg_warn("not compiled with TLS support -- " 262 "ignoring the " VAR_SMTP_SASL_AUTH_CACHE_NAME " setting"); 263 #endif 264 } 265 } 266 267 /* smtp_sasl_connect - per-session client initialization */ 268 269 void smtp_sasl_connect(SMTP_SESSION *session) 270 { 271 272 /* 273 * This initialization happens whenever we instantiate an SMTP session 274 * object. We don't instantiate a SASL client until we actually need one. 275 */ 276 session->sasl_mechanism_list = 0; 277 session->sasl_username = 0; 278 session->sasl_passwd = 0; 279 session->sasl_client = 0; 280 session->sasl_reply = 0; 281 } 282 283 /* smtp_sasl_start - per-session SASL initialization */ 284 285 void smtp_sasl_start(SMTP_SESSION *session, const char *sasl_opts_name, 286 const char *sasl_opts_val) 287 { 288 XSASL_CLIENT_CREATE_ARGS create_args; 289 290 if (msg_verbose) 291 msg_info("starting new SASL client"); 292 if ((session->sasl_client = 293 XSASL_CLIENT_CREATE(smtp_sasl_impl, &create_args, 294 stream = session->stream, 295 service = var_procname, 296 server_name = session->host, 297 security_options = sasl_opts_val)) == 0) 298 msg_fatal("SASL per-connection initialization failed"); 299 session->sasl_reply = vstring_alloc(20); 300 } 301 302 /* smtp_sasl_authenticate - run authentication protocol */ 303 304 int smtp_sasl_authenticate(SMTP_SESSION *session, DSN_BUF *why) 305 { 306 const char *myname = "smtp_sasl_authenticate"; 307 SMTP_RESP *resp; 308 const char *mechanism; 309 int result; 310 char *line; 311 int steps = 0; 312 313 /* 314 * Sanity check. 315 */ 316 if (session->sasl_mechanism_list == 0) 317 msg_panic("%s: no mechanism list", myname); 318 319 if (msg_verbose) 320 msg_info("%s: %s: SASL mechanisms %s", 321 myname, session->namaddrport, session->sasl_mechanism_list); 322 323 /* 324 * Avoid repeated login failures after a recent 535 error. 325 */ 326 #ifdef HAVE_SASL_AUTH_CACHE 327 if (smtp_sasl_auth_cache 328 && smtp_sasl_auth_cache_find(smtp_sasl_auth_cache, session)) { 329 char *resp_dsn = smtp_sasl_auth_cache_dsn(smtp_sasl_auth_cache); 330 char *resp_str = smtp_sasl_auth_cache_text(smtp_sasl_auth_cache); 331 332 if (var_smtp_sasl_auth_soft_bounce && resp_dsn[0] == '5') 333 resp_dsn[0] = '4'; 334 dsb_update(why, resp_dsn, DSB_DEF_ACTION, DSB_MTYPE_DNS, 335 session->host, var_procname, resp_str, 336 "SASL [CACHED] authentication failed; server %s said: %s", 337 session->host, resp_str); 338 return (0); 339 } 340 #endif 341 342 /* 343 * Start the client side authentication protocol. 344 */ 345 result = xsasl_client_first(session->sasl_client, 346 session->sasl_mechanism_list, 347 session->sasl_username, 348 session->sasl_passwd, 349 &mechanism, session->sasl_reply); 350 if (result != XSASL_AUTH_OK) { 351 dsb_update(why, "4.7.0", DSB_DEF_ACTION, DSB_SKIP_RMTA, 352 DSB_DTYPE_SASL, STR(session->sasl_reply), 353 "SASL authentication failed; " 354 "cannot authenticate to server %s: %s", 355 session->namaddr, STR(session->sasl_reply)); 356 return (-1); 357 } 358 359 /* 360 * Send the AUTH command and the optional initial client response. 361 * sasl_encode64() produces four bytes for each complete or incomplete 362 * triple of input bytes. Allocate an extra byte for string termination. 363 */ 364 if (LEN(session->sasl_reply) > 0) { 365 smtp_chat_cmd(session, "AUTH %s %s", mechanism, 366 STR(session->sasl_reply)); 367 } else { 368 smtp_chat_cmd(session, "AUTH %s", mechanism); 369 } 370 371 /* 372 * Step through the authentication protocol until the server tells us 373 * that we are done. 374 */ 375 while ((resp = smtp_chat_resp(session))->code / 100 == 3) { 376 377 /* 378 * Sanity check. 379 */ 380 if (++steps > 100) { 381 dsb_simple(why, "4.3.0", "SASL authentication failed; " 382 "authentication protocol loop with server %s", 383 session->namaddr); 384 return (-1); 385 } 386 387 /* 388 * Process a server challenge. 389 */ 390 line = resp->str; 391 (void) mystrtok(&line, "- \t\n"); /* skip over result code */ 392 result = xsasl_client_next(session->sasl_client, line, 393 session->sasl_reply); 394 if (result != XSASL_AUTH_OK) { 395 dsb_update(why, "4.7.0", DSB_DEF_ACTION, /* Fix 200512 */ 396 DSB_SKIP_RMTA, DSB_DTYPE_SASL, STR(session->sasl_reply), 397 "SASL authentication failed; " 398 "cannot authenticate to server %s: %s", 399 session->namaddr, STR(session->sasl_reply)); 400 return (-1); /* Fix 200512 */ 401 } 402 403 /* 404 * Send a client response. 405 */ 406 smtp_chat_cmd(session, "%s", STR(session->sasl_reply)); 407 } 408 409 /* 410 * We completed the authentication protocol. 411 */ 412 if (resp->code / 100 != 2) { 413 #ifdef HAVE_SASL_AUTH_CACHE 414 /* Update the 535 authentication failure cache. */ 415 if (smtp_sasl_auth_cache && resp->code == 535) 416 smtp_sasl_auth_cache_store(smtp_sasl_auth_cache, session, resp); 417 #endif 418 if (var_smtp_sasl_auth_soft_bounce && resp->code / 100 == 5) 419 STR(resp->dsn_buf)[0] = '4'; 420 dsb_update(why, resp->dsn, DSB_DEF_ACTION, 421 DSB_MTYPE_DNS, session->host, 422 var_procname, resp->str, 423 "SASL authentication failed; server %s said: %s", 424 session->namaddr, resp->str); 425 return (0); 426 } 427 return (1); 428 } 429 430 /* smtp_sasl_cleanup - per-session cleanup */ 431 432 void smtp_sasl_cleanup(SMTP_SESSION *session) 433 { 434 if (session->sasl_username) { 435 myfree(session->sasl_username); 436 session->sasl_username = 0; 437 } 438 if (session->sasl_passwd) { 439 myfree(session->sasl_passwd); 440 session->sasl_passwd = 0; 441 } 442 if (session->sasl_mechanism_list) { 443 /* allocated in smtp_sasl_helo_auth */ 444 myfree(session->sasl_mechanism_list); 445 session->sasl_mechanism_list = 0; 446 } 447 if (session->sasl_client) { 448 if (msg_verbose) 449 msg_info("disposing SASL state information"); 450 xsasl_client_free(session->sasl_client); 451 session->sasl_client = 0; 452 } 453 if (session->sasl_reply) { 454 vstring_free(session->sasl_reply); 455 session->sasl_reply = 0; 456 } 457 } 458 459 /* smtp_sasl_passivate - append serialized SASL attributes */ 460 461 void smtp_sasl_passivate(SMTP_SESSION *session, VSTRING *buf) 462 { 463 } 464 465 /* smtp_sasl_activate - de-serialize SASL attributes */ 466 467 int smtp_sasl_activate(SMTP_SESSION *session, char *buf) 468 { 469 return (0); 470 } 471 472 #endif 473