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 <fcntl.h>
  21 #include <unistd.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24
  25 #include "ustream-ssl.h"
  26 #include "ustream-internal.h"
  27
  28 static int urandom_fd = -1;
  29
  30 static int s_ustream_read(void *ctx, unsigned char *buf, size_t len)
  31 {
  32         struct ustream *s = ctx;
  33         char *sbuf;
  34         int slen;
  35
  36         if (s->eof)
  37                 return 0;
  38
  39         sbuf = ustream_get_read_buf(s, &slen);
  40         if (slen > len)
  41                 slen = len;
  42
  43         if (!slen)
  44                 return MBEDTLS_ERR_SSL_WANT_READ;
  45
  46         memcpy(buf, sbuf, slen);
  47         ustream_consume(s, slen);
  48
  49         return slen;
  50 }
  51
  52 static int s_ustream_write(void *ctx, const unsigned char *buf, size_t len)
  53 {
  54         struct ustream *s = ctx;
  55         int ret;
  56
  57         ret = ustream_write(s, (const char *) buf, len, false);
  58         if (ret < 0 || s->write_error)
  59                 return MBEDTLS_ERR_NET_SEND_FAILED;
  60
  61         return ret;
  62 }
  63
  64 __hidden void ustream_set_io(struct ustream_ssl_ctx *ctx, void *ssl, struct ustream *conn)
  65 {
  66         mbedtls_ssl_set_bio(ssl, conn, s_ustream_write, s_ustream_read, NULL);
  67 }
  68
  69 static bool urandom_init(void)
  70 {
  71         if (urandom_fd > -1)
  72                 return true;
  73
  74         urandom_fd = open("/dev/urandom", O_RDONLY);
  75         if (urandom_fd < 0)
  76                 return false;
  77
  78         return true;
  79 }
  80
  81 static int _urandom(void *ctx, unsigned char *out, size_t len)
  82 {
  83         if (read(urandom_fd, out, len) < 0)
  84                 return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
  85
  86         return 0;
  87 }
  88
  89 #define AES_GCM_CIPHERS(v)                              \
  90         MBEDTLS_TLS_##v##_WITH_AES_128_GCM_SHA256,      \
  91         MBEDTLS_TLS_##v##_WITH_AES_256_GCM_SHA384
  92
  93 #define AES_CBC_CIPHERS(v)                              \
  94         MBEDTLS_TLS_##v##_WITH_AES_128_CBC_SHA,         \
  95         MBEDTLS_TLS_##v##_WITH_AES_256_CBC_SHA
  96
  97 #define AES_CIPHERS(v)                                  \
  98         AES_GCM_CIPHERS(v),                             \
  99         AES_CBC_CIPHERS(v)
 100
 101 static const int default_ciphersuites_server[] =
 102 {
 103         MBEDTLS_TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256,
 104         AES_GCM_CIPHERS(ECDHE_ECDSA),
 105         MBEDTLS_TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
 106         AES_GCM_CIPHERS(ECDHE_RSA),
 107         AES_CBC_CIPHERS(ECDHE_RSA),
 108         AES_CIPHERS(RSA),
 109         0
 110 };
 111
 112 static const int default_ciphersuites_client[] =
 113 {
 114         MBEDTLS_TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256,
 115         AES_GCM_CIPHERS(ECDHE_ECDSA),
 116         MBEDTLS_TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
 117         AES_GCM_CIPHERS(ECDHE_RSA),
 118         MBEDTLS_TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
 119         AES_GCM_CIPHERS(DHE_RSA),
 120         AES_CBC_CIPHERS(ECDHE_ECDSA),
 121         AES_CBC_CIPHERS(ECDHE_RSA),
 122         AES_CBC_CIPHERS(DHE_RSA),
 123         MBEDTLS_TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA,
 124         AES_CIPHERS(RSA),
 125         MBEDTLS_TLS_RSA_WITH_3DES_EDE_CBC_SHA,
 126         0
 127 };
 128
 129
 130 __hidden struct ustream_ssl_ctx *
 131 __ustream_ssl_context_new(bool server)
 132 {
 133         struct ustream_ssl_ctx *ctx;
 134         mbedtls_ssl_config *conf;
 135         int ep;
 136
 137         if (!urandom_init())
 138                 return NULL;
 139
 140         ctx = calloc(1, sizeof(*ctx));
 141         if (!ctx)
 142                 return NULL;
 143
 144         ctx->server = server;
 145         mbedtls_pk_init(&ctx->key);
 146         mbedtls_x509_crt_init(&ctx->cert);
 147         mbedtls_x509_crt_init(&ctx->ca_cert);
 148
 149 #if defined(MBEDTLS_SSL_CACHE_C)
 150         mbedtls_ssl_cache_init(&ctx->cache);
 151         mbedtls_ssl_cache_set_timeout(&ctx->cache, 30 * 60);
 152         mbedtls_ssl_cache_set_max_entries(&ctx->cache, 5);
 153 #endif
 154
 155         conf = &ctx->conf;
 156         mbedtls_ssl_config_init(conf);
 157
 158         ep = server ? MBEDTLS_SSL_IS_SERVER : MBEDTLS_SSL_IS_CLIENT;
 159
 160         mbedtls_ssl_config_defaults(conf, ep, MBEDTLS_SSL_TRANSPORT_STREAM,
 161                                     MBEDTLS_SSL_PRESET_DEFAULT);
 162         mbedtls_ssl_conf_authmode(conf, MBEDTLS_SSL_VERIFY_NONE);
 163         mbedtls_ssl_conf_rng(conf, _urandom, NULL);
 164
 165         if (server) {
 166                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites_server);
 167                 mbedtls_ssl_conf_min_version(conf, MBEDTLS_SSL_MAJOR_VERSION_3,
 168                                              MBEDTLS_SSL_MINOR_VERSION_3);
 169         } else
 170                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites_client);
 171
 172 #if defined(MBEDTLS_SSL_CACHE_C)
 173         mbedtls_ssl_conf_session_cache(conf, &ctx->cache,
 174                                        mbedtls_ssl_cache_get,
 175                                        mbedtls_ssl_cache_set);
 176 #endif
 177         return ctx;
 178 }
 179
 180 static void ustream_ssl_update_own_cert(struct ustream_ssl_ctx *ctx)
 181 {
 182         if (!ctx->cert.version)
 183                 return;
 184
 185         if (!ctx->key.pk_info)
 186                 return;
 187
 188         mbedtls_ssl_conf_own_cert(&ctx->conf, &ctx->cert, &ctx->key);
 189 }
 190
 191 __hidden int __ustream_ssl_add_ca_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
 192 {
 193         int ret;
 194
 195         ret = mbedtls_x509_crt_parse_file(&ctx->ca_cert, file);
 196         if (ret)
 197                 return -1;
 198
 199         mbedtls_ssl_conf_ca_chain(&ctx->conf, &ctx->ca_cert, NULL);
 200         mbedtls_ssl_conf_authmode(&ctx->conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
 201         return 0;
 202 }
 203
 204 __hidden int __ustream_ssl_set_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
 205 {
 206         int ret;
 207
 208         ret = mbedtls_x509_crt_parse_file(&ctx->cert, file);
 209         if (ret)
 210                 return -1;
 211
 212         ustream_ssl_update_own_cert(ctx);
 213         return 0;
 214 }
 215
 216 __hidden int __ustream_ssl_set_key_file(struct ustream_ssl_ctx *ctx, const char *file)
 217 {
 218         int ret;
 219
 220         ret = mbedtls_pk_parse_keyfile(&ctx->key, file, NULL);
 221         if (ret)
 222                 return -1;
 223
 224         ustream_ssl_update_own_cert(ctx);
 225         return 0;
 226 }
 227
 228 __hidden int __ustream_ssl_set_ciphers(struct ustream_ssl_ctx *ctx, const char *ciphers)
 229 {
 230         int *ciphersuites = NULL, *tmp, id;
 231         char *cipherstr, *p, *last, c;
 232         size_t len = 0;
 233
 234         if (ciphers == NULL)
 235                 return -1;
 236
 237         cipherstr = strdup(ciphers);
 238
 239         if (cipherstr == NULL)
 240                 return -1;
 241
 242         for (p = cipherstr, last = p;; p++) {
 243                 if (*p == ':' || *p == 0) {
 244                         c = *p;
 245                         *p = 0;
 246
 247                         id = mbedtls_ssl_get_ciphersuite_id(last);
 248
 249                         if (id != 0) {
 250                                 tmp = realloc(ciphersuites, (len + 2) * sizeof(int));
 251
 252                                 if (tmp == NULL) {
 253                                         free(ciphersuites);
 254                                         free(cipherstr);
 255
 256                                         return -1;
 257                                 }
 258
 259                                 ciphersuites = tmp;
 260                                 ciphersuites[len++] = id;
 261                                 ciphersuites[len] = 0;
 262                         }
 263
 264                         if (c == 0)
 265                                 break;
 266
 267                         last = p + 1;
 268                 }
 269
 270                 /*
 271                  * mbedTLS expects cipher names with dashes while many sources elsewhere
 272                  * like the Firefox wiki or Wireshark specify ciphers with underscores,
 273                  * so simply convert all underscores to dashes to accept both notations.
 274                  */
 275                 else if (*p == '_') {
 276                         *p = '-';
 277                 }
 278         }
 279
 280         free(cipherstr);
 281
 282         if (len == 0)
 283                 return -1;
 284
 285         mbedtls_ssl_conf_ciphersuites(&ctx->conf, ciphersuites);
 286         free(ctx->ciphersuites);
 287
 288         ctx->ciphersuites = ciphersuites;
 289
 290         return 0;
 291 }
 292
 293 __hidden void __ustream_ssl_context_free(struct ustream_ssl_ctx *ctx)
 294 {
 295 #if defined(MBEDTLS_SSL_CACHE_C)
 296         mbedtls_ssl_cache_free(&ctx->cache);
 297 #endif
 298         mbedtls_pk_free(&ctx->key);
 299         mbedtls_x509_crt_free(&ctx->ca_cert);
 300         mbedtls_x509_crt_free(&ctx->cert);
 301         mbedtls_ssl_config_free(&ctx->conf);
 302         free(ctx->ciphersuites);
 303         free(ctx);
 304 }
 305
 306 static void ustream_ssl_error(struct ustream_ssl *us, int ret)
 307 {
 308         us->error = ret;
 309         uloop_timeout_set(&us->error_timer, 0);
 310 }
 311
 312 static bool ssl_do_wait(int ret)
 313 {
 314         switch(ret) {
 315         case MBEDTLS_ERR_SSL_WANT_READ:
 316         case MBEDTLS_ERR_SSL_WANT_WRITE:
 317                 return true;
 318         default:
 319                 return false;
 320         }
 321 }
 322
 323 static void ustream_ssl_verify_cert(struct ustream_ssl *us)
 324 {
 325         void *ssl = us->ssl;
 326         const char *msg = NULL;
 327         bool cn_mismatch;
 328         int r;
 329
 330         r = mbedtls_ssl_get_verify_result(ssl);
 331         cn_mismatch = r & MBEDTLS_X509_BADCERT_CN_MISMATCH;
 332         r &= ~MBEDTLS_X509_BADCERT_CN_MISMATCH;
 333
 334         if (r & MBEDTLS_X509_BADCERT_EXPIRED)
 335                 msg = "certificate has expired";
 336         else if (r & MBEDTLS_X509_BADCERT_REVOKED)
 337                 msg = "certificate has been revoked";
 338         else if (r & MBEDTLS_X509_BADCERT_NOT_TRUSTED)
 339                 msg = "certificate is self-signed or not signed by a trusted CA";
 340         else
 341                 msg = "unknown error";
 342
 343         if (r) {
 344                 if (us->notify_verify_error)
 345                         us->notify_verify_error(us, r, msg);
 346                 return;
 347         }
 348
 349         if (!cn_mismatch)
 350                 us->valid_cn = true;
 351 }
 352
 353 __hidden enum ssl_conn_status __ustream_ssl_connect(struct ustream_ssl *us)
 354 {
 355         void *ssl = us->ssl;
 356         int r;
 357
 358         r = mbedtls_ssl_handshake(ssl);
 359         if (r == 0) {
 360                 ustream_ssl_verify_cert(us);
 361                 return U_SSL_OK;
 362         }
 363
 364         if (ssl_do_wait(r))
 365                 return U_SSL_PENDING;
 366
 367         ustream_ssl_error(us, r);
 368         return U_SSL_ERROR;
 369 }
 370
 371 __hidden int __ustream_ssl_write(struct ustream_ssl *us, const char *buf, int len)
 372 {
 373         void *ssl = us->ssl;
 374         int done = 0, ret = 0;
 375
 376         while (done != len) {
 377                 ret = mbedtls_ssl_write(ssl, (const unsigned char *) buf + done, len - done);
 378
 379                 if (ret < 0) {
 380                         if (ssl_do_wait(ret))
 381                                 return done;
 382
 383                         ustream_ssl_error(us, ret);
 384                         return -1;
 385                 }
 386
 387                 done += ret;
 388         }
 389
 390         return done;
 391 }
 392
 393 __hidden int __ustream_ssl_read(struct ustream_ssl *us, char *buf, int len)
 394 {
 395         int ret = mbedtls_ssl_read(us->ssl, (unsigned char *) buf, len);
 396
 397         if (ret < 0) {
 398                 if (ssl_do_wait(ret))
 399                         return U_SSL_PENDING;
 400
 401                 if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY)
 402                         return 0;
 403
 404                 ustream_ssl_error(us, ret);
 405                 return U_SSL_ERROR;
 406         }
 407
 408         return ret;
 409 }
 410
 411 __hidden void *__ustream_ssl_session_new(struct ustream_ssl_ctx *ctx)
 412 {
 413         mbedtls_ssl_context *ssl;
 414
 415         ssl = calloc(1, sizeof(*ssl));
 416         if (!ssl)
 417                 return NULL;
 418
 419         mbedtls_ssl_init(ssl);
 420
 421         if (mbedtls_ssl_setup(ssl, &ctx->conf)) {
 422                 free(ssl);
 423                 return NULL;
 424         }
 425
 426         return ssl;
 427 }
 428
 429 __hidden void __ustream_ssl_session_free(void *ssl)
 430 {
 431         mbedtls_ssl_free(ssl);
 432         free(ssl);
 433 }