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