| 1 | /************************************************* |
| 2 | * Exim - an Internet mail transport agent * |
| 3 | *************************************************/ |
| 4 | |
| 5 | /* Copyright (c) University of Cambridge 1995 - 2018 */ |
| 6 | /* See the file NOTICE for conditions of use and distribution. */ |
| 7 | |
| 8 | /* Copyright (c) Twitter Inc 2012 |
| 9 | Author: Phil Pennock <pdp@exim.org> */ |
| 10 | /* Copyright (c) Phil Pennock 2012 */ |
| 11 | |
| 12 | /* Interface to GNU SASL library for generic authentication. */ |
| 13 | |
| 14 | /* Trade-offs: |
| 15 | |
| 16 | GNU SASL does not provide authentication data itself, so we have to expose |
| 17 | that decision to configuration. For some mechanisms, we need to act much |
| 18 | like plaintext. For others, we only need to be able to provide some |
| 19 | evaluated data on demand. There's no abstracted way (ie, without hardcoding |
| 20 | knowledge of authenticators here) to know which need what properties; we |
| 21 | can't query a session or the library for "we will need these for mechanism X". |
| 22 | |
| 23 | So: we always require server_condition, even if sometimes it will just be |
| 24 | set as "yes". We do provide a number of other hooks, which might not make |
| 25 | sense in all contexts. For some, we can do checks at init time. |
| 26 | */ |
| 27 | |
| 28 | #include "../exim.h" |
| 29 | |
| 30 | #ifndef AUTH_GSASL |
| 31 | /* dummy function to satisfy compilers when we link in an "empty" file. */ |
| 32 | static void dummy(int x); |
| 33 | static void dummy2(int x) { dummy(x-1); } |
| 34 | static void dummy(int x) { dummy2(x-1); } |
| 35 | #else |
| 36 | |
| 37 | #include <gsasl.h> |
| 38 | #include "gsasl_exim.h" |
| 39 | |
| 40 | /* Authenticator-specific options. */ |
| 41 | /* I did have server_*_condition options for various mechanisms, but since |
| 42 | we only ever handle one mechanism at a time, I didn't see the point in keeping |
| 43 | that. In case someone sees a point, I've left the condition_check() API |
| 44 | alone. */ |
| 45 | optionlist auth_gsasl_options[] = { |
| 46 | { "server_channelbinding", opt_bool, |
| 47 | (void *)(offsetof(auth_gsasl_options_block, server_channelbinding)) }, |
| 48 | { "server_hostname", opt_stringptr, |
| 49 | (void *)(offsetof(auth_gsasl_options_block, server_hostname)) }, |
| 50 | { "server_mech", opt_stringptr, |
| 51 | (void *)(offsetof(auth_gsasl_options_block, server_mech)) }, |
| 52 | { "server_password", opt_stringptr, |
| 53 | (void *)(offsetof(auth_gsasl_options_block, server_password)) }, |
| 54 | { "server_realm", opt_stringptr, |
| 55 | (void *)(offsetof(auth_gsasl_options_block, server_realm)) }, |
| 56 | { "server_scram_iter", opt_stringptr, |
| 57 | (void *)(offsetof(auth_gsasl_options_block, server_scram_iter)) }, |
| 58 | { "server_scram_salt", opt_stringptr, |
| 59 | (void *)(offsetof(auth_gsasl_options_block, server_scram_salt)) }, |
| 60 | { "server_service", opt_stringptr, |
| 61 | (void *)(offsetof(auth_gsasl_options_block, server_service)) } |
| 62 | }; |
| 63 | /* GSASL_SCRAM_SALTED_PASSWORD documented only for client, so not implementing |
| 64 | hooks to avoid cleartext passwords in the Exim server. */ |
| 65 | |
| 66 | int auth_gsasl_options_count = |
| 67 | sizeof(auth_gsasl_options)/sizeof(optionlist); |
| 68 | |
| 69 | /* Defaults for the authenticator-specific options. */ |
| 70 | auth_gsasl_options_block auth_gsasl_option_defaults = { |
| 71 | US"smtp", /* server_service */ |
| 72 | US"$primary_hostname", /* server_hostname */ |
| 73 | NULL, /* server_realm */ |
| 74 | NULL, /* server_mech */ |
| 75 | NULL, /* server_password */ |
| 76 | NULL, /* server_scram_iter */ |
| 77 | NULL, /* server_scram_salt */ |
| 78 | FALSE /* server_channelbinding */ |
| 79 | }; |
| 80 | |
| 81 | |
| 82 | #ifdef MACRO_PREDEF |
| 83 | |
| 84 | /* Dummy values */ |
| 85 | void auth_gsasl_init(auth_instance *ablock) {} |
| 86 | int auth_gsasl_server(auth_instance *ablock, uschar *data) {return 0;} |
| 87 | int auth_gsasl_client(auth_instance *ablock, smtp_inblock * sx, |
| 88 | int timeout, uschar *buffer, int buffsize) {return 0;} |
| 89 | void auth_gsasl_version_report(FILE *f) {} |
| 90 | |
| 91 | #else /*!MACRO_PREDEF*/ |
| 92 | |
| 93 | |
| 94 | |
| 95 | /* "Globals" for managing the gsasl interface. */ |
| 96 | |
| 97 | static Gsasl *gsasl_ctx = NULL; |
| 98 | static int |
| 99 | main_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop); |
| 100 | static int |
| 101 | server_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock); |
| 102 | static int |
| 103 | client_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock); |
| 104 | |
| 105 | static BOOL sasl_error_should_defer = FALSE; |
| 106 | static Gsasl_property callback_loop = 0; |
| 107 | static BOOL checked_server_condition = FALSE; |
| 108 | |
| 109 | enum { CURRENTLY_SERVER = 1, CURRENTLY_CLIENT = 2 }; |
| 110 | |
| 111 | struct callback_exim_state { |
| 112 | auth_instance *ablock; |
| 113 | int currently; |
| 114 | }; |
| 115 | |
| 116 | |
| 117 | /************************************************* |
| 118 | * Initialization entry point * |
| 119 | *************************************************/ |
| 120 | |
| 121 | /* Called for each instance, after its options have been read, to |
| 122 | enable consistency checks to be done, or anything else that needs |
| 123 | to be set up. */ |
| 124 | |
| 125 | void |
| 126 | auth_gsasl_init(auth_instance *ablock) |
| 127 | { |
| 128 | char *p; |
| 129 | int rc, supported; |
| 130 | auth_gsasl_options_block *ob = |
| 131 | (auth_gsasl_options_block *)(ablock->options_block); |
| 132 | |
| 133 | /* As per existing Cyrus glue, use the authenticator's public name as |
| 134 | the default for the mechanism name; we don't handle multiple mechanisms |
| 135 | in one authenticator, but the same driver can be used multiple times. */ |
| 136 | |
| 137 | if (ob->server_mech == NULL) |
| 138 | ob->server_mech = string_copy(ablock->public_name); |
| 139 | |
| 140 | /* Can get multiple session contexts from one library context, so just |
| 141 | initialise the once. */ |
| 142 | if (gsasl_ctx == NULL) { |
| 143 | rc = gsasl_init(&gsasl_ctx); |
| 144 | if (rc != GSASL_OK) { |
| 145 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " |
| 146 | "couldn't initialise GNU SASL library: %s (%s)", |
| 147 | ablock->name, gsasl_strerror_name(rc), gsasl_strerror(rc)); |
| 148 | } |
| 149 | gsasl_callback_set(gsasl_ctx, main_callback); |
| 150 | } |
| 151 | |
| 152 | /* We don't need this except to log it for debugging. */ |
| 153 | rc = gsasl_server_mechlist(gsasl_ctx, &p); |
| 154 | if (rc != GSASL_OK) |
| 155 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " |
| 156 | "failed to retrieve list of mechanisms: %s (%s)", |
| 157 | ablock->name, gsasl_strerror_name(rc), gsasl_strerror(rc)); |
| 158 | HDEBUG(D_auth) debug_printf("GNU SASL supports: %s\n", p); |
| 159 | |
| 160 | supported = gsasl_client_support_p(gsasl_ctx, CCS ob->server_mech); |
| 161 | if (!supported) |
| 162 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " |
| 163 | "GNU SASL does not support mechanism \"%s\"", |
| 164 | ablock->name, ob->server_mech); |
| 165 | |
| 166 | if ((ablock->server_condition == NULL) && |
| 167 | (streqic(ob->server_mech, US"EXTERNAL") || |
| 168 | streqic(ob->server_mech, US"ANONYMOUS") || |
| 169 | streqic(ob->server_mech, US"PLAIN") || |
| 170 | streqic(ob->server_mech, US"LOGIN"))) |
| 171 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " |
| 172 | "Need server_condition for %s mechanism", |
| 173 | ablock->name, ob->server_mech); |
| 174 | |
| 175 | /* This does *not* scale to new SASL mechanisms. Need a better way to ask |
| 176 | which properties will be needed. */ |
| 177 | if ((ob->server_realm == NULL) && |
| 178 | streqic(ob->server_mech, US"DIGEST-MD5")) |
| 179 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " |
| 180 | "Need server_realm for %s mechanism", |
| 181 | ablock->name, ob->server_mech); |
| 182 | |
| 183 | /* At present, for mechanisms we don't panic on absence of server_condition; |
| 184 | need to figure out the most generically correct approach to deciding when |
| 185 | it's critical and when it isn't. Eg, for simple validation (PLAIN mechanism, |
| 186 | etc) it clearly is critical. |
| 187 | |
| 188 | So don't activate without server_condition, this might be relaxed in the future. |
| 189 | */ |
| 190 | if (ablock->server_condition != NULL) ablock->server = TRUE; |
| 191 | ablock->client = FALSE; |
| 192 | } |
| 193 | |
| 194 | |
| 195 | /* GNU SASL uses one top-level callback, registered at library level. |
| 196 | We dispatch to client and server functions instead. */ |
| 197 | |
| 198 | static int |
| 199 | main_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop) |
| 200 | { |
| 201 | int rc = 0; |
| 202 | struct callback_exim_state *cb_state = |
| 203 | (struct callback_exim_state *)gsasl_session_hook_get(sctx); |
| 204 | |
| 205 | HDEBUG(D_auth) |
| 206 | debug_printf("GNU SASL Callback entered, prop=%d (loop prop=%d)\n", |
| 207 | prop, callback_loop); |
| 208 | |
| 209 | if (cb_state == NULL) |
| 210 | { |
| 211 | HDEBUG(D_auth) debug_printf(" not from our server/client processing.\n"); |
| 212 | return GSASL_NO_CALLBACK; |
| 213 | } |
| 214 | |
| 215 | if (callback_loop > 0) |
| 216 | { |
| 217 | /* Most likely is that we were asked for property foo, and to |
| 218 | expand the string we asked for property bar to put into an auth |
| 219 | variable, but property bar is not supplied for this mechanism. */ |
| 220 | HDEBUG(D_auth) |
| 221 | debug_printf("Loop, asked for property %d while handling property %d\n", |
| 222 | prop, callback_loop); |
| 223 | return GSASL_NO_CALLBACK; |
| 224 | } |
| 225 | callback_loop = prop; |
| 226 | |
| 227 | if (cb_state->currently == CURRENTLY_CLIENT) |
| 228 | rc = client_callback(ctx, sctx, prop, cb_state->ablock); |
| 229 | else if (cb_state->currently == CURRENTLY_SERVER) |
| 230 | rc = server_callback(ctx, sctx, prop, cb_state->ablock); |
| 231 | else |
| 232 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " |
| 233 | "unhandled callback state, bug in Exim", cb_state->ablock->name); |
| 234 | /* NOTREACHED */ |
| 235 | |
| 236 | callback_loop = 0; |
| 237 | return rc; |
| 238 | } |
| 239 | |
| 240 | |
| 241 | /************************************************* |
| 242 | * Server entry point * |
| 243 | *************************************************/ |
| 244 | |
| 245 | /* For interface, see auths/README */ |
| 246 | |
| 247 | int |
| 248 | auth_gsasl_server(auth_instance *ablock, uschar *initial_data) |
| 249 | { |
| 250 | char *tmps; |
| 251 | char *to_send, *received; |
| 252 | Gsasl_session *sctx = NULL; |
| 253 | auth_gsasl_options_block *ob = |
| 254 | (auth_gsasl_options_block *)(ablock->options_block); |
| 255 | struct callback_exim_state cb_state; |
| 256 | int rc, auth_result, exim_error, exim_error_override; |
| 257 | |
| 258 | HDEBUG(D_auth) |
| 259 | debug_printf("GNU SASL: initialising session for %s, mechanism %s.\n", |
| 260 | ablock->name, ob->server_mech); |
| 261 | |
| 262 | rc = gsasl_server_start(gsasl_ctx, CCS ob->server_mech, &sctx); |
| 263 | if (rc != GSASL_OK) |
| 264 | { |
| 265 | auth_defer_msg = string_sprintf("GNU SASL: session start failure: %s (%s)", |
| 266 | gsasl_strerror_name(rc), gsasl_strerror(rc)); |
| 267 | HDEBUG(D_auth) debug_printf("%s\n", auth_defer_msg); |
| 268 | return DEFER; |
| 269 | } |
| 270 | /* Hereafter: gsasl_finish(sctx) please */ |
| 271 | |
| 272 | gsasl_session_hook_set(sctx, (void *)ablock); |
| 273 | cb_state.ablock = ablock; |
| 274 | cb_state.currently = CURRENTLY_SERVER; |
| 275 | gsasl_session_hook_set(sctx, (void *)&cb_state); |
| 276 | |
| 277 | tmps = CS expand_string(ob->server_service); |
| 278 | gsasl_property_set(sctx, GSASL_SERVICE, tmps); |
| 279 | tmps = CS expand_string(ob->server_hostname); |
| 280 | gsasl_property_set(sctx, GSASL_HOSTNAME, tmps); |
| 281 | if (ob->server_realm) |
| 282 | { |
| 283 | tmps = CS expand_string(ob->server_realm); |
| 284 | if (tmps && *tmps) |
| 285 | gsasl_property_set(sctx, GSASL_REALM, tmps); |
| 286 | } |
| 287 | /* We don't support protection layers. */ |
| 288 | gsasl_property_set(sctx, GSASL_QOPS, "qop-auth"); |
| 289 | #ifndef DISABLE_TLS |
| 290 | if (tls_channelbinding_b64) |
| 291 | { |
| 292 | /* Some auth mechanisms can ensure that both sides are talking withing the |
| 293 | same security context; for TLS, this means that even if a bad certificate |
| 294 | has been accepted, they remain MitM-proof because both sides must be within |
| 295 | the same negotiated session; if someone is terminating one session and |
| 296 | proxying data on within a second, authentication will fail. |
| 297 | |
| 298 | We might not have this available, depending upon TLS implementation, |
| 299 | ciphersuite, phase of moon ... |
| 300 | |
| 301 | If we do, it results in extra SASL mechanisms being available; here, |
| 302 | Exim's one-mechanism-per-authenticator potentially causes problems. |
| 303 | It depends upon how GNU SASL will implement the PLUS variants of GS2 |
| 304 | and whether it automatically mandates a switch to the bound PLUS |
| 305 | if the data is available. Since default-on, despite being more secure, |
| 306 | would then result in mechanism name changes on a library update, we |
| 307 | have little choice but to default it off and let the admin choose to |
| 308 | enable it. *sigh* |
| 309 | */ |
| 310 | if (ob->server_channelbinding) |
| 311 | { |
| 312 | HDEBUG(D_auth) debug_printf("Auth %s: Enabling channel-binding\n", |
| 313 | ablock->name); |
| 314 | gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, |
| 315 | CCS tls_channelbinding_b64); |
| 316 | } |
| 317 | else |
| 318 | { |
| 319 | HDEBUG(D_auth) |
| 320 | debug_printf("Auth %s: Not enabling channel-binding (data available)\n", |
| 321 | ablock->name); |
| 322 | } |
| 323 | } |
| 324 | else |
| 325 | HDEBUG(D_auth) |
| 326 | debug_printf("Auth %s: no channel-binding data available\n", |
| 327 | ablock->name); |
| 328 | #endif |
| 329 | |
| 330 | checked_server_condition = FALSE; |
| 331 | |
| 332 | received = CS initial_data; |
| 333 | to_send = NULL; |
| 334 | exim_error = exim_error_override = OK; |
| 335 | |
| 336 | do { |
| 337 | rc = gsasl_step64(sctx, received, &to_send); |
| 338 | |
| 339 | switch (rc) |
| 340 | { |
| 341 | case GSASL_OK: |
| 342 | if (!to_send) |
| 343 | goto STOP_INTERACTION; |
| 344 | break; |
| 345 | |
| 346 | case GSASL_NEEDS_MORE: |
| 347 | break; |
| 348 | |
| 349 | case GSASL_AUTHENTICATION_ERROR: |
| 350 | case GSASL_INTEGRITY_ERROR: |
| 351 | case GSASL_NO_AUTHID: |
| 352 | case GSASL_NO_ANONYMOUS_TOKEN: |
| 353 | case GSASL_NO_AUTHZID: |
| 354 | case GSASL_NO_PASSWORD: |
| 355 | case GSASL_NO_PASSCODE: |
| 356 | case GSASL_NO_PIN: |
| 357 | case GSASL_BASE64_ERROR: |
| 358 | HDEBUG(D_auth) debug_printf("GNU SASL permanent error: %s (%s)\n", |
| 359 | gsasl_strerror_name(rc), gsasl_strerror(rc)); |
| 360 | log_write(0, LOG_REJECT, "%s authenticator (%s):\n " |
| 361 | "GNU SASL permanent failure: %s (%s)", |
| 362 | ablock->name, ob->server_mech, |
| 363 | gsasl_strerror_name(rc), gsasl_strerror(rc)); |
| 364 | if (rc == GSASL_BASE64_ERROR) |
| 365 | exim_error_override = BAD64; |
| 366 | goto STOP_INTERACTION; |
| 367 | |
| 368 | default: |
| 369 | auth_defer_msg = string_sprintf("GNU SASL temporary error: %s (%s)", |
| 370 | gsasl_strerror_name(rc), gsasl_strerror(rc)); |
| 371 | HDEBUG(D_auth) debug_printf("%s\n", auth_defer_msg); |
| 372 | exim_error_override = DEFER; |
| 373 | goto STOP_INTERACTION; |
| 374 | } |
| 375 | |
| 376 | if ((rc == GSASL_NEEDS_MORE) || |
| 377 | (to_send && *to_send)) |
| 378 | exim_error = |
| 379 | auth_get_no64_data((uschar **)&received, US to_send); |
| 380 | |
| 381 | if (to_send) |
| 382 | { |
| 383 | free(to_send); |
| 384 | to_send = NULL; |
| 385 | } |
| 386 | |
| 387 | if (exim_error) |
| 388 | break; /* handles * cancelled check */ |
| 389 | |
| 390 | } while (rc == GSASL_NEEDS_MORE); |
| 391 | |
| 392 | STOP_INTERACTION: |
| 393 | auth_result = rc; |
| 394 | |
| 395 | gsasl_finish(sctx); |
| 396 | |
| 397 | /* Can return: OK DEFER FAIL CANCELLED BAD64 UNEXPECTED */ |
| 398 | |
| 399 | if (exim_error != OK) |
| 400 | return exim_error; |
| 401 | |
| 402 | if (auth_result != GSASL_OK) |
| 403 | { |
| 404 | HDEBUG(D_auth) debug_printf("authentication returned %s (%s)\n", |
| 405 | gsasl_strerror_name(auth_result), gsasl_strerror(auth_result)); |
| 406 | if (exim_error_override != OK) |
| 407 | return exim_error_override; /* might be DEFER */ |
| 408 | if (sasl_error_should_defer) /* overriding auth failure SASL error */ |
| 409 | return DEFER; |
| 410 | return FAIL; |
| 411 | } |
| 412 | |
| 413 | /* Auth succeeded, check server_condition unless already done in callback */ |
| 414 | return checked_server_condition ? OK : auth_check_serv_cond(ablock); |
| 415 | } |
| 416 | |
| 417 | |
| 418 | /* returns the GSASL status of expanding the Exim string given */ |
| 419 | static int |
| 420 | condition_check(auth_instance *ablock, uschar *label, uschar *condition_string) |
| 421 | { |
| 422 | int exim_rc; |
| 423 | |
| 424 | exim_rc = auth_check_some_cond(ablock, label, condition_string, FAIL); |
| 425 | |
| 426 | if (exim_rc == OK) |
| 427 | return GSASL_OK; |
| 428 | else if (exim_rc == DEFER) |
| 429 | { |
| 430 | sasl_error_should_defer = TRUE; |
| 431 | return GSASL_AUTHENTICATION_ERROR; |
| 432 | } |
| 433 | else if (exim_rc == FAIL) |
| 434 | return GSASL_AUTHENTICATION_ERROR; |
| 435 | |
| 436 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator: " |
| 437 | "Unhandled return from checking %s: %d", |
| 438 | ablock->name, label, exim_rc); |
| 439 | /* NOTREACHED */ |
| 440 | return GSASL_AUTHENTICATION_ERROR; |
| 441 | } |
| 442 | |
| 443 | static int |
| 444 | server_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock) |
| 445 | { |
| 446 | char *tmps; |
| 447 | uschar *propval; |
| 448 | int cbrc = GSASL_NO_CALLBACK; |
| 449 | auth_gsasl_options_block *ob = |
| 450 | (auth_gsasl_options_block *)(ablock->options_block); |
| 451 | |
| 452 | HDEBUG(D_auth) |
| 453 | debug_printf("GNU SASL callback %d for %s/%s as server\n", |
| 454 | prop, ablock->name, ablock->public_name); |
| 455 | |
| 456 | for (int i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL; |
| 457 | expand_nmax = 0; |
| 458 | |
| 459 | switch (prop) |
| 460 | { |
| 461 | case GSASL_VALIDATE_SIMPLE: |
| 462 | /* GSASL_AUTHID, GSASL_AUTHZID, and GSASL_PASSWORD */ |
| 463 | propval = US gsasl_property_fast(sctx, GSASL_AUTHID); |
| 464 | auth_vars[0] = expand_nstring[1] = propval ? string_copy(propval) : US""; |
| 465 | propval = US gsasl_property_fast(sctx, GSASL_AUTHZID); |
| 466 | auth_vars[1] = expand_nstring[2] = propval ? string_copy(propval) : US""; |
| 467 | propval = US gsasl_property_fast(sctx, GSASL_PASSWORD); |
| 468 | auth_vars[2] = expand_nstring[3] = propval ? string_copy(propval) : US""; |
| 469 | expand_nmax = 3; |
| 470 | for (int i = 1; i <= 3; ++i) |
| 471 | expand_nlength[i] = Ustrlen(expand_nstring[i]); |
| 472 | |
| 473 | cbrc = condition_check(ablock, US"server_condition", ablock->server_condition); |
| 474 | checked_server_condition = TRUE; |
| 475 | break; |
| 476 | |
| 477 | case GSASL_VALIDATE_EXTERNAL: |
| 478 | if (ablock->server_condition == NULL) |
| 479 | { |
| 480 | HDEBUG(D_auth) debug_printf("No server_condition supplied, to validate EXTERNAL.\n"); |
| 481 | cbrc = GSASL_AUTHENTICATION_ERROR; |
| 482 | break; |
| 483 | } |
| 484 | propval = US gsasl_property_fast(sctx, GSASL_AUTHZID); |
| 485 | /* We always set $auth1, even if only to empty string. */ |
| 486 | auth_vars[0] = expand_nstring[1] = propval ? string_copy(propval) : US""; |
| 487 | expand_nlength[1] = Ustrlen(expand_nstring[1]); |
| 488 | expand_nmax = 1; |
| 489 | |
| 490 | cbrc = condition_check(ablock, |
| 491 | US"server_condition (EXTERNAL)", ablock->server_condition); |
| 492 | checked_server_condition = TRUE; |
| 493 | break; |
| 494 | |
| 495 | case GSASL_VALIDATE_ANONYMOUS: |
| 496 | if (ablock->server_condition == NULL) |
| 497 | { |
| 498 | HDEBUG(D_auth) debug_printf("No server_condition supplied, to validate ANONYMOUS.\n"); |
| 499 | cbrc = GSASL_AUTHENTICATION_ERROR; |
| 500 | break; |
| 501 | } |
| 502 | propval = US gsasl_property_fast(sctx, GSASL_ANONYMOUS_TOKEN); |
| 503 | /* We always set $auth1, even if only to empty string. */ |
| 504 | auth_vars[0] = expand_nstring[1] = propval ? string_copy(propval) : US""; |
| 505 | expand_nlength[1] = Ustrlen(expand_nstring[1]); |
| 506 | expand_nmax = 1; |
| 507 | |
| 508 | cbrc = condition_check(ablock, |
| 509 | US"server_condition (ANONYMOUS)", ablock->server_condition); |
| 510 | checked_server_condition = TRUE; |
| 511 | break; |
| 512 | |
| 513 | case GSASL_VALIDATE_GSSAPI: |
| 514 | /* GSASL_AUTHZID and GSASL_GSSAPI_DISPLAY_NAME |
| 515 | The display-name is authenticated as part of GSS, the authzid is claimed |
| 516 | by the SASL integration after authentication; protected against tampering |
| 517 | (if the SASL mechanism supports that, which Kerberos does) but is |
| 518 | unverified, same as normal for other mechanisms. |
| 519 | |
| 520 | First coding, we had these values swapped, but for consistency and prior |
| 521 | to the first release of Exim with this authenticator, they've been |
| 522 | switched to match the ordering of GSASL_VALIDATE_SIMPLE. */ |
| 523 | propval = US gsasl_property_fast(sctx, GSASL_GSSAPI_DISPLAY_NAME); |
| 524 | auth_vars[0] = expand_nstring[1] = propval ? string_copy(propval) : US""; |
| 525 | propval = US gsasl_property_fast(sctx, GSASL_AUTHZID); |
| 526 | auth_vars[1] = expand_nstring[2] = propval ? string_copy(propval) : US""; |
| 527 | expand_nmax = 2; |
| 528 | for (int i = 1; i <= 2; ++i) |
| 529 | expand_nlength[i] = Ustrlen(expand_nstring[i]); |
| 530 | |
| 531 | /* In this one case, it perhaps makes sense to default back open? |
| 532 | But for consistency, let's just mandate server_condition here too. */ |
| 533 | cbrc = condition_check(ablock, |
| 534 | US"server_condition (GSSAPI family)", ablock->server_condition); |
| 535 | checked_server_condition = TRUE; |
| 536 | break; |
| 537 | |
| 538 | case GSASL_PASSWORD: |
| 539 | /* DIGEST-MD5: GSASL_AUTHID, GSASL_AUTHZID and GSASL_REALM |
| 540 | CRAM-MD5: GSASL_AUTHID |
| 541 | PLAIN: GSASL_AUTHID and GSASL_AUTHZID |
| 542 | LOGIN: GSASL_AUTHID |
| 543 | */ |
| 544 | if (ob->server_scram_iter) |
| 545 | { |
| 546 | tmps = CS expand_string(ob->server_scram_iter); |
| 547 | gsasl_property_set(sctx, GSASL_SCRAM_ITER, tmps); |
| 548 | } |
| 549 | if (ob->server_scram_salt) |
| 550 | { |
| 551 | tmps = CS expand_string(ob->server_scram_salt); |
| 552 | gsasl_property_set(sctx, GSASL_SCRAM_SALT, tmps); |
| 553 | } |
| 554 | /* Asking for GSASL_AUTHZID calls back into us if we use |
| 555 | gsasl_property_get(), thus the use of gsasl_property_fast(). |
| 556 | Do we really want to hardcode limits per mechanism? What happens when |
| 557 | a new mechanism is added to the library. It *shouldn't* result in us |
| 558 | needing to add more glue, since avoiding that is a large part of the |
| 559 | point of SASL. */ |
| 560 | propval = US gsasl_property_fast(sctx, GSASL_AUTHID); |
| 561 | auth_vars[0] = expand_nstring[1] = propval ? string_copy(propval) : US""; |
| 562 | propval = US gsasl_property_fast(sctx, GSASL_AUTHZID); |
| 563 | auth_vars[1] = expand_nstring[2] = propval ? string_copy(propval) : US""; |
| 564 | propval = US gsasl_property_fast(sctx, GSASL_REALM); |
| 565 | auth_vars[2] = expand_nstring[3] = propval ? string_copy(propval) : US""; |
| 566 | expand_nmax = 3; |
| 567 | for (int i = 1; i <= 3; ++i) |
| 568 | expand_nlength[i] = Ustrlen(expand_nstring[i]); |
| 569 | |
| 570 | tmps = CS expand_string(ob->server_password); |
| 571 | if (tmps == NULL) |
| 572 | { |
| 573 | sasl_error_should_defer = f.expand_string_forcedfail ? FALSE : TRUE; |
| 574 | HDEBUG(D_auth) debug_printf("server_password expansion failed, so " |
| 575 | "can't tell GNU SASL library the password for %s\n", auth_vars[0]); |
| 576 | return GSASL_AUTHENTICATION_ERROR; |
| 577 | } |
| 578 | gsasl_property_set(sctx, GSASL_PASSWORD, tmps); |
| 579 | /* This is inadequate; don't think Exim's store stacks are geared |
| 580 | for memory wiping, so expanding strings will leave stuff laying around. |
| 581 | But no need to compound the problem, so get rid of the one we can. */ |
| 582 | memset(tmps, '\0', strlen(tmps)); |
| 583 | cbrc = GSASL_OK; |
| 584 | break; |
| 585 | |
| 586 | default: |
| 587 | HDEBUG(D_auth) debug_printf("Unrecognised callback: %d\n", prop); |
| 588 | cbrc = GSASL_NO_CALLBACK; |
| 589 | } |
| 590 | |
| 591 | HDEBUG(D_auth) debug_printf("Returning %s (%s)\n", |
| 592 | gsasl_strerror_name(cbrc), gsasl_strerror(cbrc)); |
| 593 | |
| 594 | return cbrc; |
| 595 | } |
| 596 | |
| 597 | |
| 598 | /************************************************* |
| 599 | * Client entry point * |
| 600 | *************************************************/ |
| 601 | |
| 602 | /* For interface, see auths/README */ |
| 603 | |
| 604 | int |
| 605 | auth_gsasl_client( |
| 606 | auth_instance *ablock, /* authenticator block */ |
| 607 | smtp_inblock * sx, /* connection */ |
| 608 | int timeout, /* command timeout */ |
| 609 | uschar *buffer, /* buffer for reading response */ |
| 610 | int buffsize) /* size of buffer */ |
| 611 | { |
| 612 | HDEBUG(D_auth) |
| 613 | debug_printf("Client side NOT IMPLEMENTED: you should not see this!\n"); |
| 614 | /* NOT IMPLEMENTED */ |
| 615 | return FAIL; |
| 616 | } |
| 617 | |
| 618 | static int |
| 619 | client_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock) |
| 620 | { |
| 621 | int cbrc = GSASL_NO_CALLBACK; |
| 622 | HDEBUG(D_auth) |
| 623 | debug_printf("GNU SASL callback %d for %s/%s as client\n", |
| 624 | prop, ablock->name, ablock->public_name); |
| 625 | |
| 626 | HDEBUG(D_auth) |
| 627 | debug_printf("Client side NOT IMPLEMENTED: you should not see this!\n"); |
| 628 | |
| 629 | return cbrc; |
| 630 | } |
| 631 | |
| 632 | /************************************************* |
| 633 | * Diagnostic API * |
| 634 | *************************************************/ |
| 635 | |
| 636 | void |
| 637 | auth_gsasl_version_report(FILE *f) |
| 638 | { |
| 639 | const char *runtime; |
| 640 | runtime = gsasl_check_version(NULL); |
| 641 | fprintf(f, "Library version: GNU SASL: Compile: %s\n" |
| 642 | " Runtime: %s\n", |
| 643 | GSASL_VERSION, runtime); |
| 644 | } |
| 645 | |
| 646 | #endif /*!MACRO_PREDEF*/ |
| 647 | #endif /* AUTH_GSASL */ |
| 648 | |
| 649 | /* End of gsasl_exim.c */ |