ustream-mbedtls.c

   1 /*
   2  * ustream-ssl - library for SSL over ustream
   3  *
   4  * Copyright (C) 2012 Felix Fietkau <nbd@openwrt.org>
   5  *
   6  * Permission to use, copy, modify, and/or distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 #include <sys/types.h>
  20 #include <sys/random.h>
  21 #include <fcntl.h>
  22 #include <unistd.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25
  26 #include "ustream-ssl.h"
  27 #include "ustream-internal.h"
  28 #include <psa/crypto.h>
  29 #include <mbedtls/debug.h>
  30
  31 static void debug_cb(void *ctx_p, int level,
  32                      const char *file, int line,
  33                      const char *str)
  34 {
  35         struct ustream_ssl_ctx *ctx = ctx_p;
  36         const char *fstr;
  37         char buf[512];
  38         int len;
  39
  40         if (!ctx->debug_cb)
  41                 return;
  42
  43         while ((fstr = strstr(file + 1, "library/")) != NULL)
  44                 file = fstr;
  45
  46         len = snprintf(buf, sizeof(buf), "%s:%04d: %s", file, line, str);
  47         if (len >= (int)sizeof(buf))
  48                 len = (int)sizeof(buf) - 1;
  49         if (buf[len - 1] == '\n')
  50                 buf[len - 1] = 0;
  51         ctx->debug_cb(ctx->debug_cb_priv, level, buf);
  52 }
  53
  54 static int s_ustream_read(void *ctx, unsigned char *buf, size_t len)
  55 {
  56         struct ustream *s = ctx;
  57         char *sbuf;
  58         int slen;
  59
  60         if (s->eof)
  61                 return 0;
  62
  63         sbuf = ustream_get_read_buf(s, &slen);
  64         if ((size_t) slen > len)
  65                 slen = len;
  66
  67         if (!slen)
  68                 return MBEDTLS_ERR_SSL_WANT_READ;
  69
  70         memcpy(buf, sbuf, slen);
  71         ustream_consume(s, slen);
  72
  73         return slen;
  74 }
  75
  76 static int s_ustream_write(void *ctx, const unsigned char *buf, size_t len)
  77 {
  78         struct ustream *s = ctx;
  79         int ret;
  80
  81         ret = ustream_write(s, (const char *) buf, len, false);
  82         if (ret < 0 || s->write_error)
  83                 return MBEDTLS_ERR_NET_SEND_FAILED;
  84
  85         return ret;
  86 }
  87
  88 __hidden void ustream_set_io(struct ustream_ssl_ctx *ctx, void *ssl, struct ustream *conn)
  89 {
  90         mbedtls_ssl_set_bio(ssl, conn, s_ustream_write, s_ustream_read, NULL);
  91 }
  92
  93 static int _random(void *ctx, unsigned char *out, size_t len)
  94 {
  95 #ifdef linux
  96         if (getrandom(out, len, 0) != (ssize_t) len)
  97                 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
  98 #else
  99         static FILE *f;
 100
 101         if (!f)
 102                 f = fopen("/dev/urandom", "r");
 103         if (fread(out, len, 1, f) != 1)
 104                 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
 105 #endif
 106
 107         return 0;
 108 }
 109
 110 #define AES_GCM_CIPHERS(v)                              \
 111         MBEDTLS_TLS_##v##_WITH_AES_128_GCM_SHA256,      \
 112         MBEDTLS_TLS_##v##_WITH_AES_256_GCM_SHA384
 113
 114 #define AES_CBC_CIPHERS(v)                              \
 115         MBEDTLS_TLS_##v##_WITH_AES_128_CBC_SHA,         \
 116         MBEDTLS_TLS_##v##_WITH_AES_256_CBC_SHA
 117
 118 #define AES_CIPHERS(v)                                  \
 119         AES_GCM_CIPHERS(v),                             \
 120         AES_CBC_CIPHERS(v)
 121
 122 static const int default_ciphersuites_server[] =
 123 {
 124 #ifdef MBEDTLS_SSL_PROTO_TLS1_3
 125         MBEDTLS_TLS1_3_CHACHA20_POLY1305_SHA256,
 126         MBEDTLS_TLS1_3_AES_256_GCM_SHA384,
 127         MBEDTLS_TLS1_3_AES_128_GCM_SHA256,
 128         MBEDTLS_TLS1_3_AES_128_CCM_SHA256,
 129         MBEDTLS_TLS1_3_AES_128_CCM_8_SHA256,
 130 #endif
 131
 132         MBEDTLS_TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256,
 133         AES_GCM_CIPHERS(ECDHE_ECDSA),
 134         MBEDTLS_TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
 135         AES_GCM_CIPHERS(ECDHE_RSA),
 136         AES_CBC_CIPHERS(ECDHE_RSA),
 137         AES_CIPHERS(RSA),
 138         0
 139 };
 140
 141 static const int default_ciphersuites_client[] =
 142 {
 143 #ifdef MBEDTLS_SSL_PROTO_TLS1_3
 144         MBEDTLS_TLS1_3_CHACHA20_POLY1305_SHA256,
 145         MBEDTLS_TLS1_3_AES_256_GCM_SHA384,
 146         MBEDTLS_TLS1_3_AES_128_GCM_SHA256,
 147         MBEDTLS_TLS1_3_AES_128_CCM_SHA256,
 148         MBEDTLS_TLS1_3_AES_128_CCM_8_SHA256,
 149 #endif
 150
 151         MBEDTLS_TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256,
 152         AES_GCM_CIPHERS(ECDHE_ECDSA),
 153         MBEDTLS_TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
 154         AES_GCM_CIPHERS(ECDHE_RSA),
 155         MBEDTLS_TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
 156         AES_GCM_CIPHERS(DHE_RSA),
 157         AES_CBC_CIPHERS(ECDHE_ECDSA),
 158         AES_CBC_CIPHERS(ECDHE_RSA),
 159         AES_CBC_CIPHERS(DHE_RSA),
 160 /* Removed in Mbed TLS 3.0.0 */
 161 #ifdef MBEDTLS_TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA
 162         MBEDTLS_TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA,
 163 #endif
 164         AES_CIPHERS(RSA),
 165 /* Removed in Mbed TLS 3.0.0 */
 166 #ifdef MBEDTLS_TLS_RSA_WITH_3DES_EDE_CBC_SHA
 167         MBEDTLS_TLS_RSA_WITH_3DES_EDE_CBC_SHA,
 168 #endif
 169         0
 170 };
 171
 172
 173 __hidden struct ustream_ssl_ctx *
 174 __ustream_ssl_context_new(bool server)
 175 {
 176         struct ustream_ssl_ctx *ctx;
 177         mbedtls_ssl_config *conf;
 178         int ep;
 179
 180 #ifdef MBEDTLS_PSA_CRYPTO_C
 181         static bool psa_init;
 182
 183         if (!psa_init && !psa_crypto_init())
 184                 psa_init = true;
 185 #endif
 186
 187         ctx = calloc(1, sizeof(*ctx));
 188         if (!ctx)
 189                 return NULL;
 190
 191         ctx->server = server;
 192         mbedtls_pk_init(&ctx->key);
 193         mbedtls_x509_crt_init(&ctx->cert);
 194         mbedtls_x509_crt_init(&ctx->ca_cert);
 195
 196 #if defined(MBEDTLS_SSL_CACHE_C)
 197         mbedtls_ssl_cache_init(&ctx->cache);
 198         mbedtls_ssl_cache_set_timeout(&ctx->cache, 30 * 60);
 199         mbedtls_ssl_cache_set_max_entries(&ctx->cache, 5);
 200 #endif
 201
 202         conf = &ctx->conf;
 203         mbedtls_ssl_config_init(conf);
 204
 205         ep = server ? MBEDTLS_SSL_IS_SERVER : MBEDTLS_SSL_IS_CLIENT;
 206
 207         mbedtls_ssl_config_defaults(conf, ep, MBEDTLS_SSL_TRANSPORT_STREAM,
 208                                     MBEDTLS_SSL_PRESET_DEFAULT);
 209         mbedtls_ssl_conf_rng(conf, _random, NULL);
 210
 211         if (server) {
 212                 mbedtls_ssl_conf_authmode(conf, MBEDTLS_SSL_VERIFY_NONE);
 213                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites_server);
 214                 mbedtls_ssl_conf_min_version(conf, MBEDTLS_SSL_MAJOR_VERSION_3,
 215                                              MBEDTLS_SSL_MINOR_VERSION_3);
 216         } else {
 217                 mbedtls_ssl_conf_authmode(conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
 218                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites_client);
 219         }
 220
 221 #if defined(MBEDTLS_SSL_CACHE_C)
 222         mbedtls_ssl_conf_session_cache(conf, &ctx->cache,
 223                                        mbedtls_ssl_cache_get,
 224                                        mbedtls_ssl_cache_set);
 225 #endif
 226         return ctx;
 227 }
 228
 229 static void ustream_ssl_update_own_cert(struct ustream_ssl_ctx *ctx)
 230 {
 231         if (!ctx->cert.version)
 232                 return;
 233
 234         if (mbedtls_pk_get_type(&ctx->key) == MBEDTLS_PK_NONE)
 235                 return;
 236
 237         mbedtls_ssl_conf_own_cert(&ctx->conf, &ctx->cert, &ctx->key);
 238 }
 239
 240 __hidden int __ustream_ssl_add_ca_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
 241 {
 242         int ret;
 243
 244         ret = mbedtls_x509_crt_parse_file(&ctx->ca_cert, file);
 245         if (ret)
 246                 return -1;
 247
 248         mbedtls_ssl_conf_ca_chain(&ctx->conf, &ctx->ca_cert, NULL);
 249         mbedtls_ssl_conf_authmode(&ctx->conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
 250         return 0;
 251 }
 252
 253 __hidden int __ustream_ssl_set_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
 254 {
 255         int ret;
 256
 257         ret = mbedtls_x509_crt_parse_file(&ctx->cert, file);
 258         if (ret)
 259                 return -1;
 260
 261         ustream_ssl_update_own_cert(ctx);
 262         return 0;
 263 }
 264
 265 __hidden int __ustream_ssl_set_key_file(struct ustream_ssl_ctx *ctx, const char *file)
 266 {
 267         int ret;
 268
 269 #if (MBEDTLS_VERSION_NUMBER >= 0x03000000)
 270         ret = mbedtls_pk_parse_keyfile(&ctx->key, file, NULL, _random, NULL);
 271 #else
 272         ret = mbedtls_pk_parse_keyfile(&ctx->key, file, NULL);
 273 #endif
 274         if (ret)
 275                 return -1;
 276
 277         ustream_ssl_update_own_cert(ctx);
 278         return 0;
 279 }
 280
 281 __hidden int __ustream_ssl_set_ciphers(struct ustream_ssl_ctx *ctx, const char *ciphers)
 282 {
 283         int *ciphersuites = NULL, *tmp, id;
 284         char *cipherstr, *p, *last, c;
 285         size_t len = 0;
 286
 287         if (ciphers == NULL)
 288                 return -1;
 289
 290         cipherstr = strdup(ciphers);
 291
 292         if (cipherstr == NULL)
 293                 return -1;
 294
 295         for (p = cipherstr, last = p;; p++) {
 296                 if (*p == ':' || *p == 0) {
 297                         c = *p;
 298                         *p = 0;
 299
 300                         id = mbedtls_ssl_get_ciphersuite_id(last);
 301
 302                         if (id != 0) {
 303                                 tmp = realloc(ciphersuites, (len + 2) * sizeof(int));
 304
 305                                 if (tmp == NULL) {
 306                                         free(ciphersuites);
 307                                         free(cipherstr);
 308
 309                                         return -1;
 310                                 }
 311
 312                                 ciphersuites = tmp;
 313                                 ciphersuites[len++] = id;
 314                                 ciphersuites[len] = 0;
 315                         }
 316
 317                         if (c == 0)
 318                                 break;
 319
 320                         last = p + 1;
 321                 }
 322
 323                 /*
 324                  * mbedTLS expects cipher names with dashes while many sources elsewhere
 325                  * like the Firefox wiki or Wireshark specify ciphers with underscores,
 326                  * so simply convert all underscores to dashes to accept both notations.
 327                  */
 328                 else if (*p == '_') {
 329                         *p = '-';
 330                 }
 331         }
 332
 333         free(cipherstr);
 334
 335         if (len == 0)
 336                 return -1;
 337
 338         mbedtls_ssl_conf_ciphersuites(&ctx->conf, ciphersuites);
 339         free(ctx->ciphersuites);
 340
 341         ctx->ciphersuites = ciphersuites;
 342
 343         return 0;
 344 }
 345
 346 __hidden int __ustream_ssl_set_require_validation(struct ustream_ssl_ctx *ctx, bool require)
 347 {
 348         int mode = MBEDTLS_SSL_VERIFY_OPTIONAL;
 349
 350         if (!require)
 351                 mode = MBEDTLS_SSL_VERIFY_NONE;
 352
 353         /* force TLS 1.2 when not requiring validation for now */
 354         if (!require && !ctx->server)
 355                 mbedtls_ssl_conf_max_version(&ctx->conf, MBEDTLS_SSL_MAJOR_VERSION_3,
 356                                              MBEDTLS_SSL_MINOR_VERSION_3);
 357         mbedtls_ssl_conf_authmode(&ctx->conf, mode);
 358
 359         return 0;
 360 }
 361
 362 __hidden void __ustream_ssl_context_free(struct ustream_ssl_ctx *ctx)
 363 {
 364         free(ctx->session_data);
 365 #if defined(MBEDTLS_SSL_CACHE_C)
 366         mbedtls_ssl_cache_free(&ctx->cache);
 367 #endif
 368         mbedtls_pk_free(&ctx->key);
 369         mbedtls_x509_crt_free(&ctx->ca_cert);
 370         mbedtls_x509_crt_free(&ctx->cert);
 371         mbedtls_ssl_config_free(&ctx->conf);
 372         free(ctx->ciphersuites);
 373         free(ctx);
 374 }
 375
 376 static void ustream_ssl_error(struct ustream_ssl *us, int ret)
 377 {
 378         us->error = ret;
 379         uloop_timeout_set(&us->error_timer, 0);
 380 }
 381
 382 static void
 383 __ustream_ssl_save_session(struct ustream_ssl *us)
 384 {
 385         struct ustream_ssl_ctx *ctx = us->ctx;
 386         mbedtls_ssl_session sess;
 387
 388         if (ctx->server)
 389                 return;
 390
 391         free(ctx->session_data);
 392         ctx->session_data = NULL;
 393
 394         mbedtls_ssl_session_init(&sess);
 395         if (mbedtls_ssl_get_session(us->ssl, &sess) != 0)
 396                 return;
 397
 398         mbedtls_ssl_session_save(&sess, NULL, 0, &ctx->session_data_len);
 399         ctx->session_data = malloc(ctx->session_data_len);
 400         if (mbedtls_ssl_session_save(&sess, ctx->session_data, ctx->session_data_len,
 401                                      &ctx->session_data_len))
 402                 ctx->session_data_len = 0;
 403         mbedtls_ssl_session_free(&sess);
 404 }
 405
 406 static int ssl_check_return(struct ustream_ssl *us, int ret)
 407 {
 408         switch(ret) {
 409         case MBEDTLS_ERR_SSL_WANT_READ:
 410         case MBEDTLS_ERR_SSL_WANT_WRITE:
 411                 return U_SSL_PENDING;
 412         case MBEDTLS_ERR_SSL_RECEIVED_NEW_SESSION_TICKET:
 413 #ifdef MBEDTLS_ECP_RESTARTABLE
 414         case MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS:
 415 #endif
 416                 __ustream_ssl_save_session(us);
 417                 return U_SSL_RETRY;
 418         case MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY:
 419         case MBEDTLS_ERR_NET_CONN_RESET:
 420                 return 0;
 421         default:
 422                 ustream_ssl_error(us, ret);
 423                 return U_SSL_ERROR;
 424         }
 425 }
 426
 427 static void ustream_ssl_verify_cert(struct ustream_ssl *us)
 428 {
 429         void *ssl = us->ssl;
 430         const char *msg = NULL;
 431         bool cn_mismatch;
 432         int r;
 433
 434         r = mbedtls_ssl_get_verify_result(ssl);
 435         cn_mismatch = r & MBEDTLS_X509_BADCERT_CN_MISMATCH;
 436         r &= ~MBEDTLS_X509_BADCERT_CN_MISMATCH;
 437
 438         if (r & MBEDTLS_X509_BADCERT_EXPIRED)
 439                 msg = "certificate has expired";
 440         else if (r & MBEDTLS_X509_BADCERT_REVOKED)
 441                 msg = "certificate has been revoked";
 442         else if (r & MBEDTLS_X509_BADCERT_NOT_TRUSTED)
 443                 msg = "certificate is self-signed or not signed by a trusted CA";
 444         else
 445                 msg = "unknown error";
 446
 447         if (r) {
 448                 if (us->notify_verify_error)
 449                         us->notify_verify_error(us, r, msg);
 450                 return;
 451         }
 452
 453         if (!cn_mismatch)
 454                 us->valid_cn = true;
 455 }
 456
 457 __hidden enum ssl_conn_status __ustream_ssl_connect(struct ustream_ssl *us)
 458 {
 459         void *ssl = us->ssl;
 460         int r;
 461
 462         do {
 463                 r = mbedtls_ssl_handshake(ssl);
 464                 if (r == 0) {
 465                         ustream_ssl_verify_cert(us);
 466                         return U_SSL_OK;
 467                 }
 468
 469                 r = ssl_check_return(us, r);
 470         } while (r == U_SSL_RETRY);
 471
 472         return r;
 473 }
 474
 475 __hidden int __ustream_ssl_write(struct ustream_ssl *us, const char *buf, int len)
 476 {
 477         void *ssl = us->ssl;
 478         int done = 0, ret = 0;
 479
 480         while (done != len) {
 481                 ret = mbedtls_ssl_write(ssl, (const unsigned char *) buf + done, len - done);
 482                 if (ret < 0) {
 483                         ret = ssl_check_return(us, ret);
 484                         if (ret == U_SSL_RETRY)
 485                                 continue;
 486
 487                         if (ret == U_SSL_PENDING)
 488                                 return done;
 489
 490                         return -1;
 491                 }
 492
 493                 done += ret;
 494         }
 495
 496         return done;
 497 }
 498
 499 __hidden int __ustream_ssl_read(struct ustream_ssl *us, char *buf, int len)
 500 {
 501         int ret;
 502
 503         do {
 504                 ret = mbedtls_ssl_read(us->ssl, (unsigned char *) buf, len);
 505                 if (ret >= 0)
 506                         return ret;
 507
 508                 ret = ssl_check_return(us, ret);
 509         } while (ret == U_SSL_RETRY);
 510
 511         return ret;
 512 }
 513
 514 __hidden void __ustream_ssl_set_debug(struct ustream_ssl_ctx *ctx, int level,
 515                                       ustream_ssl_debug_cb cb, void *cb_priv)
 516 {
 517         ctx->debug_cb = cb;
 518         ctx->debug_cb_priv = cb_priv;
 519         mbedtls_ssl_conf_dbg(&ctx->conf, debug_cb, ctx);
 520 #ifdef MBEDTLS_DEBUG_C
 521         mbedtls_debug_set_threshold(level);
 522 #endif
 523 }
 524
 525 __hidden void *__ustream_ssl_session_new(struct ustream_ssl_ctx *ctx)
 526 {
 527         mbedtls_ssl_context *ssl;
 528         mbedtls_ssl_session sess;
 529
 530         ssl = calloc(1, sizeof(*ssl));
 531         if (!ssl)
 532                 return NULL;
 533
 534         mbedtls_ssl_init(ssl);
 535
 536         if (mbedtls_ssl_setup(ssl, &ctx->conf)) {
 537                 free(ssl);
 538                 return NULL;
 539         }
 540
 541         if (!ctx->session_data_len)
 542                 return ssl;
 543
 544         mbedtls_ssl_session_init(&sess);
 545         if (mbedtls_ssl_session_load(&sess, ctx->session_data, ctx->session_data_len) == 0)
 546                 mbedtls_ssl_set_session(ssl, &sess);
 547
 548         return ssl;
 549 }
 550
 551 __hidden void __ustream_ssl_session_free(void *ssl)
 552 {
 553         mbedtls_ssl_free(ssl);
 554         free(ssl);
 555 }