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         MBEDTLS_TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256,
 125         AES_GCM_CIPHERS(ECDHE_ECDSA),
 126         MBEDTLS_TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
 127         AES_GCM_CIPHERS(ECDHE_RSA),
 128         AES_CBC_CIPHERS(ECDHE_RSA),
 129         AES_CIPHERS(RSA),
 130         0
 131 };
 132
 133 static const int default_ciphersuites_client[] =
 134 {
 135         MBEDTLS_TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256,
 136         AES_GCM_CIPHERS(ECDHE_ECDSA),
 137         MBEDTLS_TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
 138         AES_GCM_CIPHERS(ECDHE_RSA),
 139         MBEDTLS_TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
 140         AES_GCM_CIPHERS(DHE_RSA),
 141         AES_CBC_CIPHERS(ECDHE_ECDSA),
 142         AES_CBC_CIPHERS(ECDHE_RSA),
 143         AES_CBC_CIPHERS(DHE_RSA),
 144 /* Removed in Mbed TLS 3.0.0 */
 145 #ifdef MBEDTLS_TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA
 146         MBEDTLS_TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA,
 147 #endif
 148         AES_CIPHERS(RSA),
 149 /* Removed in Mbed TLS 3.0.0 */
 150 #ifdef MBEDTLS_TLS_RSA_WITH_3DES_EDE_CBC_SHA
 151         MBEDTLS_TLS_RSA_WITH_3DES_EDE_CBC_SHA,
 152 #endif
 153         0
 154 };
 155
 156
 157 __hidden struct ustream_ssl_ctx *
 158 __ustream_ssl_context_new(bool server)
 159 {
 160         struct ustream_ssl_ctx *ctx;
 161         mbedtls_ssl_config *conf;
 162         int ep;
 163
 164 #ifdef MBEDTLS_PSA_CRYPTO_C
 165         static bool psa_init;
 166
 167         if (!psa_init && !psa_crypto_init())
 168                 psa_init = true;
 169 #endif
 170
 171         ctx = calloc(1, sizeof(*ctx));
 172         if (!ctx)
 173                 return NULL;
 174
 175         ctx->server = server;
 176         mbedtls_pk_init(&ctx->key);
 177         mbedtls_x509_crt_init(&ctx->cert);
 178         mbedtls_x509_crt_init(&ctx->ca_cert);
 179
 180 #if defined(MBEDTLS_SSL_CACHE_C)
 181         mbedtls_ssl_cache_init(&ctx->cache);
 182         mbedtls_ssl_cache_set_timeout(&ctx->cache, 30 * 60);
 183         mbedtls_ssl_cache_set_max_entries(&ctx->cache, 5);
 184 #endif
 185
 186         conf = &ctx->conf;
 187         mbedtls_ssl_config_init(conf);
 188
 189         ep = server ? MBEDTLS_SSL_IS_SERVER : MBEDTLS_SSL_IS_CLIENT;
 190
 191         mbedtls_ssl_config_defaults(conf, ep, MBEDTLS_SSL_TRANSPORT_STREAM,
 192                                     MBEDTLS_SSL_PRESET_DEFAULT);
 193         mbedtls_ssl_conf_rng(conf, _random, NULL);
 194
 195         if (server) {
 196                 mbedtls_ssl_conf_authmode(conf, MBEDTLS_SSL_VERIFY_NONE);
 197                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites_server);
 198                 mbedtls_ssl_conf_min_version(conf, MBEDTLS_SSL_MAJOR_VERSION_3,
 199                                              MBEDTLS_SSL_MINOR_VERSION_3);
 200         } else {
 201                 mbedtls_ssl_conf_authmode(conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
 202                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites_client);
 203         }
 204
 205 #if defined(MBEDTLS_SSL_CACHE_C)
 206         mbedtls_ssl_conf_session_cache(conf, &ctx->cache,
 207                                        mbedtls_ssl_cache_get,
 208                                        mbedtls_ssl_cache_set);
 209 #endif
 210         return ctx;
 211 }
 212
 213 static void ustream_ssl_update_own_cert(struct ustream_ssl_ctx *ctx)
 214 {
 215         if (!ctx->cert.version)
 216                 return;
 217
 218         if (mbedtls_pk_get_type(&ctx->key) == MBEDTLS_PK_NONE)
 219                 return;
 220
 221         mbedtls_ssl_conf_own_cert(&ctx->conf, &ctx->cert, &ctx->key);
 222 }
 223
 224 __hidden int __ustream_ssl_add_ca_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
 225 {
 226         int ret;
 227
 228         ret = mbedtls_x509_crt_parse_file(&ctx->ca_cert, file);
 229         if (ret)
 230                 return -1;
 231
 232         mbedtls_ssl_conf_ca_chain(&ctx->conf, &ctx->ca_cert, NULL);
 233         mbedtls_ssl_conf_authmode(&ctx->conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
 234         return 0;
 235 }
 236
 237 __hidden int __ustream_ssl_set_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
 238 {
 239         int ret;
 240
 241         ret = mbedtls_x509_crt_parse_file(&ctx->cert, file);
 242         if (ret)
 243                 return -1;
 244
 245         ustream_ssl_update_own_cert(ctx);
 246         return 0;
 247 }
 248
 249 __hidden int __ustream_ssl_set_key_file(struct ustream_ssl_ctx *ctx, const char *file)
 250 {
 251         int ret;
 252
 253 #if (MBEDTLS_VERSION_NUMBER >= 0x03000000)
 254         ret = mbedtls_pk_parse_keyfile(&ctx->key, file, NULL, _random, NULL);
 255 #else
 256         ret = mbedtls_pk_parse_keyfile(&ctx->key, file, NULL);
 257 #endif
 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_ciphers(struct ustream_ssl_ctx *ctx, const char *ciphers)
 266 {
 267         int *ciphersuites = NULL, *tmp, id;
 268         char *cipherstr, *p, *last, c;
 269         size_t len = 0;
 270
 271         if (ciphers == NULL)
 272                 return -1;
 273
 274         cipherstr = strdup(ciphers);
 275
 276         if (cipherstr == NULL)
 277                 return -1;
 278
 279         for (p = cipherstr, last = p;; p++) {
 280                 if (*p == ':' || *p == 0) {
 281                         c = *p;
 282                         *p = 0;
 283
 284                         id = mbedtls_ssl_get_ciphersuite_id(last);
 285
 286                         if (id != 0) {
 287                                 tmp = realloc(ciphersuites, (len + 2) * sizeof(int));
 288
 289                                 if (tmp == NULL) {
 290                                         free(ciphersuites);
 291                                         free(cipherstr);
 292
 293                                         return -1;
 294                                 }
 295
 296                                 ciphersuites = tmp;
 297                                 ciphersuites[len++] = id;
 298                                 ciphersuites[len] = 0;
 299                         }
 300
 301                         if (c == 0)
 302                                 break;
 303
 304                         last = p + 1;
 305                 }
 306
 307                 /*
 308                  * mbedTLS expects cipher names with dashes while many sources elsewhere
 309                  * like the Firefox wiki or Wireshark specify ciphers with underscores,
 310                  * so simply convert all underscores to dashes to accept both notations.
 311                  */
 312                 else if (*p == '_') {
 313                         *p = '-';
 314                 }
 315         }
 316
 317         free(cipherstr);
 318
 319         if (len == 0)
 320                 return -1;
 321
 322         mbedtls_ssl_conf_ciphersuites(&ctx->conf, ciphersuites);
 323         free(ctx->ciphersuites);
 324
 325         ctx->ciphersuites = ciphersuites;
 326
 327         return 0;
 328 }
 329
 330 __hidden int __ustream_ssl_set_require_validation(struct ustream_ssl_ctx *ctx, bool require)
 331 {
 332         int mode = MBEDTLS_SSL_VERIFY_OPTIONAL;
 333
 334         if (!require)
 335                 mode = MBEDTLS_SSL_VERIFY_NONE;
 336
 337         mbedtls_ssl_conf_authmode(&ctx->conf, mode);
 338
 339         return 0;
 340 }
 341
 342 __hidden void __ustream_ssl_context_free(struct ustream_ssl_ctx *ctx)
 343 {
 344 #if defined(MBEDTLS_SSL_CACHE_C)
 345         mbedtls_ssl_cache_free(&ctx->cache);
 346 #endif
 347         mbedtls_pk_free(&ctx->key);
 348         mbedtls_x509_crt_free(&ctx->ca_cert);
 349         mbedtls_x509_crt_free(&ctx->cert);
 350         mbedtls_ssl_config_free(&ctx->conf);
 351         free(ctx->ciphersuites);
 352         free(ctx);
 353 }
 354
 355 static void ustream_ssl_error(struct ustream_ssl *us, int ret)
 356 {
 357         us->error = ret;
 358         uloop_timeout_set(&us->error_timer, 0);
 359 }
 360
 361 static bool ssl_do_wait(int ret)
 362 {
 363         switch(ret) {
 364         case MBEDTLS_ERR_SSL_WANT_READ:
 365         case MBEDTLS_ERR_SSL_WANT_WRITE:
 366                 return true;
 367         default:
 368                 return false;
 369         }
 370 }
 371
 372 static void ustream_ssl_verify_cert(struct ustream_ssl *us)
 373 {
 374         void *ssl = us->ssl;
 375         const char *msg = NULL;
 376         bool cn_mismatch;
 377         int r;
 378
 379         r = mbedtls_ssl_get_verify_result(ssl);
 380         cn_mismatch = r & MBEDTLS_X509_BADCERT_CN_MISMATCH;
 381         r &= ~MBEDTLS_X509_BADCERT_CN_MISMATCH;
 382
 383         if (r & MBEDTLS_X509_BADCERT_EXPIRED)
 384                 msg = "certificate has expired";
 385         else if (r & MBEDTLS_X509_BADCERT_REVOKED)
 386                 msg = "certificate has been revoked";
 387         else if (r & MBEDTLS_X509_BADCERT_NOT_TRUSTED)
 388                 msg = "certificate is self-signed or not signed by a trusted CA";
 389         else
 390                 msg = "unknown error";
 391
 392         if (r) {
 393                 if (us->notify_verify_error)
 394                         us->notify_verify_error(us, r, msg);
 395                 return;
 396         }
 397
 398         if (!cn_mismatch)
 399                 us->valid_cn = true;
 400 }
 401
 402 __hidden enum ssl_conn_status __ustream_ssl_connect(struct ustream_ssl *us)
 403 {
 404         void *ssl = us->ssl;
 405         int r;
 406
 407         r = mbedtls_ssl_handshake(ssl);
 408         if (r == 0) {
 409                 ustream_ssl_verify_cert(us);
 410                 return U_SSL_OK;
 411         }
 412
 413         if (ssl_do_wait(r))
 414                 return U_SSL_PENDING;
 415
 416         ustream_ssl_error(us, r);
 417         return U_SSL_ERROR;
 418 }
 419
 420 __hidden int __ustream_ssl_write(struct ustream_ssl *us, const char *buf, int len)
 421 {
 422         void *ssl = us->ssl;
 423         int done = 0, ret = 0;
 424
 425         while (done != len) {
 426                 ret = mbedtls_ssl_write(ssl, (const unsigned char *) buf + done, len - done);
 427
 428                 if (ret < 0) {
 429                         if (ssl_do_wait(ret))
 430                                 return done;
 431
 432                         ustream_ssl_error(us, ret);
 433                         return -1;
 434                 }
 435
 436                 done += ret;
 437         }
 438
 439         return done;
 440 }
 441
 442 __hidden int __ustream_ssl_read(struct ustream_ssl *us, char *buf, int len)
 443 {
 444         int ret = mbedtls_ssl_read(us->ssl, (unsigned char *) buf, len);
 445
 446         if (ret < 0) {
 447                 if (ssl_do_wait(ret))
 448                         return U_SSL_PENDING;
 449
 450                 if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY)
 451                         return 0;
 452
 453                 ustream_ssl_error(us, ret);
 454                 return U_SSL_ERROR;
 455         }
 456
 457         return ret;
 458 }
 459
 460 __hidden void __ustream_ssl_set_debug(struct ustream_ssl_ctx *ctx, int level,
 461                                       ustream_ssl_debug_cb cb, void *cb_priv)
 462 {
 463         ctx->debug_cb = cb;
 464         ctx->debug_cb_priv = cb_priv;
 465         mbedtls_ssl_conf_dbg(&ctx->conf, debug_cb, ctx);
 466         mbedtls_debug_set_threshold(level);
 467 }
 468
 469 __hidden void *__ustream_ssl_session_new(struct ustream_ssl_ctx *ctx)
 470 {
 471         mbedtls_ssl_context *ssl;
 472
 473         ssl = calloc(1, sizeof(*ssl));
 474         if (!ssl)
 475                 return NULL;
 476
 477         mbedtls_ssl_init(ssl);
 478
 479         if (mbedtls_ssl_setup(ssl, &ctx->conf)) {
 480                 free(ssl);
 481                 return NULL;
 482         }
 483
 484         return ssl;
 485 }
 486
 487 __hidden void __ustream_ssl_session_free(void *ssl)
 488 {
 489         mbedtls_ssl_free(ssl);
 490         free(ssl);
 491 }