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
  29 static int s_ustream_read(void *ctx, unsigned char *buf, size_t len)
  30 {
  31         struct ustream *s = ctx;
  32         char *sbuf;
  33         int slen;
  34
  35         if (s->eof)
  36                 return 0;
  37
  38         sbuf = ustream_get_read_buf(s, &slen);
  39         if ((size_t) slen > len)
  40                 slen = len;
  41
  42         if (!slen)
  43                 return MBEDTLS_ERR_SSL_WANT_READ;
  44
  45         memcpy(buf, sbuf, slen);
  46         ustream_consume(s, slen);
  47
  48         return slen;
  49 }
  50
  51 static int s_ustream_write(void *ctx, const unsigned char *buf, size_t len)
  52 {
  53         struct ustream *s = ctx;
  54         int ret;
  55
  56         ret = ustream_write(s, (const char *) buf, len, false);
  57         if (ret < 0 || s->write_error)
  58                 return MBEDTLS_ERR_NET_SEND_FAILED;
  59
  60         return ret;
  61 }
  62
  63 __hidden void ustream_set_io(struct ustream_ssl_ctx *ctx, void *ssl, struct ustream *conn)
  64 {
  65         mbedtls_ssl_set_bio(ssl, conn, s_ustream_write, s_ustream_read, NULL);
  66 }
  67
  68 static int _random(void *ctx, unsigned char *out, size_t len)
  69 {
  70 #ifdef linux
  71         if (getrandom(out, len, 0) != (ssize_t) len)
  72                 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
  73 #else
  74         static FILE *f;
  75
  76         if (!f)
  77                 f = fopen("/dev/urandom", "r");
  78         if (fread(out, len, 1, f) != 1)
  79                 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
  80 #endif
  81
  82         return 0;
  83 }
  84
  85 #define AES_GCM_CIPHERS(v)                              \
  86         MBEDTLS_TLS_##v##_WITH_AES_128_GCM_SHA256,      \
  87         MBEDTLS_TLS_##v##_WITH_AES_256_GCM_SHA384
  88
  89 #define AES_CBC_CIPHERS(v)                              \
  90         MBEDTLS_TLS_##v##_WITH_AES_128_CBC_SHA,         \
  91         MBEDTLS_TLS_##v##_WITH_AES_256_CBC_SHA
  92
  93 #define AES_CIPHERS(v)                                  \
  94         AES_GCM_CIPHERS(v),                             \
  95         AES_CBC_CIPHERS(v)
  96
  97 static const int default_ciphersuites_server[] =
  98 {
  99         MBEDTLS_TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256,
 100         AES_GCM_CIPHERS(ECDHE_ECDSA),
 101         MBEDTLS_TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
 102         AES_GCM_CIPHERS(ECDHE_RSA),
 103         AES_CBC_CIPHERS(ECDHE_RSA),
 104         AES_CIPHERS(RSA),
 105         0
 106 };
 107
 108 static const int default_ciphersuites_client[] =
 109 {
 110         MBEDTLS_TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256,
 111         AES_GCM_CIPHERS(ECDHE_ECDSA),
 112         MBEDTLS_TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
 113         AES_GCM_CIPHERS(ECDHE_RSA),
 114         MBEDTLS_TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
 115         AES_GCM_CIPHERS(DHE_RSA),
 116         AES_CBC_CIPHERS(ECDHE_ECDSA),
 117         AES_CBC_CIPHERS(ECDHE_RSA),
 118         AES_CBC_CIPHERS(DHE_RSA),
 119 /* Removed in Mbed TLS 3.0.0 */
 120 #ifdef MBEDTLS_TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA
 121         MBEDTLS_TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA,
 122 #endif
 123         AES_CIPHERS(RSA),
 124 /* Removed in Mbed TLS 3.0.0 */
 125 #ifdef MBEDTLS_TLS_RSA_WITH_3DES_EDE_CBC_SHA
 126         MBEDTLS_TLS_RSA_WITH_3DES_EDE_CBC_SHA,
 127 #endif
 128         0
 129 };
 130
 131
 132 __hidden struct ustream_ssl_ctx *
 133 __ustream_ssl_context_new(bool server)
 134 {
 135         struct ustream_ssl_ctx *ctx;
 136         mbedtls_ssl_config *conf;
 137         int ep;
 138
 139         ctx = calloc(1, sizeof(*ctx));
 140         if (!ctx)
 141                 return NULL;
 142
 143         ctx->server = server;
 144         mbedtls_pk_init(&ctx->key);
 145         mbedtls_x509_crt_init(&ctx->cert);
 146         mbedtls_x509_crt_init(&ctx->ca_cert);
 147
 148 #if defined(MBEDTLS_SSL_CACHE_C)
 149         mbedtls_ssl_cache_init(&ctx->cache);
 150         mbedtls_ssl_cache_set_timeout(&ctx->cache, 30 * 60);
 151         mbedtls_ssl_cache_set_max_entries(&ctx->cache, 5);
 152 #endif
 153
 154         conf = &ctx->conf;
 155         mbedtls_ssl_config_init(conf);
 156
 157         ep = server ? MBEDTLS_SSL_IS_SERVER : MBEDTLS_SSL_IS_CLIENT;
 158
 159         mbedtls_ssl_config_defaults(conf, ep, MBEDTLS_SSL_TRANSPORT_STREAM,
 160                                     MBEDTLS_SSL_PRESET_DEFAULT);
 161         mbedtls_ssl_conf_rng(conf, _random, NULL);
 162
 163         if (server) {
 164                 mbedtls_ssl_conf_authmode(conf, MBEDTLS_SSL_VERIFY_NONE);
 165                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites_server);
 166                 mbedtls_ssl_conf_min_version(conf, MBEDTLS_SSL_MAJOR_VERSION_3,
 167                                              MBEDTLS_SSL_MINOR_VERSION_3);
 168         } else {
 169                 mbedtls_ssl_conf_authmode(conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
 170                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites_client);
 171         }
 172
 173 #if defined(MBEDTLS_SSL_CACHE_C)
 174         mbedtls_ssl_conf_session_cache(conf, &ctx->cache,
 175                                        mbedtls_ssl_cache_get,
 176                                        mbedtls_ssl_cache_set);
 177 #endif
 178         return ctx;
 179 }
 180
 181 static void ustream_ssl_update_own_cert(struct ustream_ssl_ctx *ctx)
 182 {
 183         if (!ctx->cert.version)
 184                 return;
 185
 186         if (mbedtls_pk_get_type(&ctx->key) == MBEDTLS_PK_NONE)
 187                 return;
 188
 189         mbedtls_ssl_conf_own_cert(&ctx->conf, &ctx->cert, &ctx->key);
 190 }
 191
 192 __hidden int __ustream_ssl_add_ca_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
 193 {
 194         int ret;
 195
 196         ret = mbedtls_x509_crt_parse_file(&ctx->ca_cert, file);
 197         if (ret)
 198                 return -1;
 199
 200         mbedtls_ssl_conf_ca_chain(&ctx->conf, &ctx->ca_cert, NULL);
 201         mbedtls_ssl_conf_authmode(&ctx->conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
 202         return 0;
 203 }
 204
 205 __hidden int __ustream_ssl_set_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
 206 {
 207         int ret;
 208
 209         ret = mbedtls_x509_crt_parse_file(&ctx->cert, file);
 210         if (ret)
 211                 return -1;
 212
 213         ustream_ssl_update_own_cert(ctx);
 214         return 0;
 215 }
 216
 217 __hidden int __ustream_ssl_set_key_file(struct ustream_ssl_ctx *ctx, const char *file)
 218 {
 219         int ret;
 220
 221 #if (MBEDTLS_VERSION_NUMBER >= 0x03000000)
 222         ret = mbedtls_pk_parse_keyfile(&ctx->key, file, NULL, _random, NULL);
 223 #else
 224         ret = mbedtls_pk_parse_keyfile(&ctx->key, file, NULL);
 225 #endif
 226         if (ret)
 227                 return -1;
 228
 229         ustream_ssl_update_own_cert(ctx);
 230         return 0;
 231 }
 232
 233 __hidden int __ustream_ssl_set_ciphers(struct ustream_ssl_ctx *ctx, const char *ciphers)
 234 {
 235         int *ciphersuites = NULL, *tmp, id;
 236         char *cipherstr, *p, *last, c;
 237         size_t len = 0;
 238
 239         if (ciphers == NULL)
 240                 return -1;
 241
 242         cipherstr = strdup(ciphers);
 243
 244         if (cipherstr == NULL)
 245                 return -1;
 246
 247         for (p = cipherstr, last = p;; p++) {
 248                 if (*p == ':' || *p == 0) {
 249                         c = *p;
 250                         *p = 0;
 251
 252                         id = mbedtls_ssl_get_ciphersuite_id(last);
 253
 254                         if (id != 0) {
 255                                 tmp = realloc(ciphersuites, (len + 2) * sizeof(int));
 256
 257                                 if (tmp == NULL) {
 258                                         free(ciphersuites);
 259                                         free(cipherstr);
 260
 261                                         return -1;
 262                                 }
 263
 264                                 ciphersuites = tmp;
 265                                 ciphersuites[len++] = id;
 266                                 ciphersuites[len] = 0;
 267                         }
 268
 269                         if (c == 0)
 270                                 break;
 271
 272                         last = p + 1;
 273                 }
 274
 275                 /*
 276                  * mbedTLS expects cipher names with dashes while many sources elsewhere
 277                  * like the Firefox wiki or Wireshark specify ciphers with underscores,
 278                  * so simply convert all underscores to dashes to accept both notations.
 279                  */
 280                 else if (*p == '_') {
 281                         *p = '-';
 282                 }
 283         }
 284
 285         free(cipherstr);
 286
 287         if (len == 0)
 288                 return -1;
 289
 290         mbedtls_ssl_conf_ciphersuites(&ctx->conf, ciphersuites);
 291         free(ctx->ciphersuites);
 292
 293         ctx->ciphersuites = ciphersuites;
 294
 295         return 0;
 296 }
 297
 298 __hidden int __ustream_ssl_set_require_validation(struct ustream_ssl_ctx *ctx, bool require)
 299 {
 300         int mode = MBEDTLS_SSL_VERIFY_OPTIONAL;
 301
 302         if (!require)
 303                 mode = MBEDTLS_SSL_VERIFY_NONE;
 304
 305         mbedtls_ssl_conf_authmode(&ctx->conf, mode);
 306
 307         return 0;
 308 }
 309
 310 __hidden void __ustream_ssl_context_free(struct ustream_ssl_ctx *ctx)
 311 {
 312 #if defined(MBEDTLS_SSL_CACHE_C)
 313         mbedtls_ssl_cache_free(&ctx->cache);
 314 #endif
 315         mbedtls_pk_free(&ctx->key);
 316         mbedtls_x509_crt_free(&ctx->ca_cert);
 317         mbedtls_x509_crt_free(&ctx->cert);
 318         mbedtls_ssl_config_free(&ctx->conf);
 319         free(ctx->ciphersuites);
 320         free(ctx);
 321 }
 322
 323 static void ustream_ssl_error(struct ustream_ssl *us, int ret)
 324 {
 325         us->error = ret;
 326         uloop_timeout_set(&us->error_timer, 0);
 327 }
 328
 329 static bool ssl_do_wait(int ret)
 330 {
 331         switch(ret) {
 332         case MBEDTLS_ERR_SSL_WANT_READ:
 333         case MBEDTLS_ERR_SSL_WANT_WRITE:
 334                 return true;
 335         default:
 336                 return false;
 337         }
 338 }
 339
 340 static void ustream_ssl_verify_cert(struct ustream_ssl *us)
 341 {
 342         void *ssl = us->ssl;
 343         const char *msg = NULL;
 344         bool cn_mismatch;
 345         int r;
 346
 347         r = mbedtls_ssl_get_verify_result(ssl);
 348         cn_mismatch = r & MBEDTLS_X509_BADCERT_CN_MISMATCH;
 349         r &= ~MBEDTLS_X509_BADCERT_CN_MISMATCH;
 350
 351         if (r & MBEDTLS_X509_BADCERT_EXPIRED)
 352                 msg = "certificate has expired";
 353         else if (r & MBEDTLS_X509_BADCERT_REVOKED)
 354                 msg = "certificate has been revoked";
 355         else if (r & MBEDTLS_X509_BADCERT_NOT_TRUSTED)
 356                 msg = "certificate is self-signed or not signed by a trusted CA";
 357         else
 358                 msg = "unknown error";
 359
 360         if (r) {
 361                 if (us->notify_verify_error)
 362                         us->notify_verify_error(us, r, msg);
 363                 return;
 364         }
 365
 366         if (!cn_mismatch)
 367                 us->valid_cn = true;
 368 }
 369
 370 __hidden enum ssl_conn_status __ustream_ssl_connect(struct ustream_ssl *us)
 371 {
 372         void *ssl = us->ssl;
 373         int r;
 374
 375         r = mbedtls_ssl_handshake(ssl);
 376         if (r == 0) {
 377                 ustream_ssl_verify_cert(us);
 378                 return U_SSL_OK;
 379         }
 380
 381         if (ssl_do_wait(r))
 382                 return U_SSL_PENDING;
 383
 384         ustream_ssl_error(us, r);
 385         return U_SSL_ERROR;
 386 }
 387
 388 __hidden int __ustream_ssl_write(struct ustream_ssl *us, const char *buf, int len)
 389 {
 390         void *ssl = us->ssl;
 391         int done = 0, ret = 0;
 392
 393         while (done != len) {
 394                 ret = mbedtls_ssl_write(ssl, (const unsigned char *) buf + done, len - done);
 395
 396                 if (ret < 0) {
 397                         if (ssl_do_wait(ret))
 398                                 return done;
 399
 400                         ustream_ssl_error(us, ret);
 401                         return -1;
 402                 }
 403
 404                 done += ret;
 405         }
 406
 407         return done;
 408 }
 409
 410 __hidden int __ustream_ssl_read(struct ustream_ssl *us, char *buf, int len)
 411 {
 412         int ret = mbedtls_ssl_read(us->ssl, (unsigned char *) buf, len);
 413
 414         if (ret < 0) {
 415                 if (ssl_do_wait(ret))
 416                         return U_SSL_PENDING;
 417
 418                 if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY)
 419                         return 0;
 420
 421                 ustream_ssl_error(us, ret);
 422                 return U_SSL_ERROR;
 423         }
 424
 425         return ret;
 426 }
 427
 428 __hidden void *__ustream_ssl_session_new(struct ustream_ssl_ctx *ctx)
 429 {
 430         mbedtls_ssl_context *ssl;
 431
 432         ssl = calloc(1, sizeof(*ssl));
 433         if (!ssl)
 434                 return NULL;
 435
 436         mbedtls_ssl_init(ssl);
 437
 438         if (mbedtls_ssl_setup(ssl, &ctx->conf)) {
 439                 free(ssl);
 440                 return NULL;
 441         }
 442
 443         return ssl;
 444 }
 445
 446 __hidden void __ustream_ssl_session_free(void *ssl)
 447 {
 448         mbedtls_ssl_free(ssl);
 449         free(ssl);
 450 }