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