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 TLS_DEFAULT_CIPHERS                     \
  90     TLS_CIPHER(AES_256_CBC_SHA256)              \
  91     TLS_CIPHER(AES_256_GCM_SHA384)              \
  92     TLS_CIPHER(AES_256_CBC_SHA)                 \
  93     TLS_CIPHER(CAMELLIA_256_CBC_SHA256)         \
  94     TLS_CIPHER(CAMELLIA_256_CBC_SHA)            \
  95     TLS_CIPHER(AES_128_CBC_SHA256)              \
  96     TLS_CIPHER(AES_128_GCM_SHA256)              \
  97     TLS_CIPHER(AES_128_CBC_SHA)                 \
  98     TLS_CIPHER(CAMELLIA_128_CBC_SHA256)         \
  99     TLS_CIPHER(CAMELLIA_128_CBC_SHA)            \
 100     TLS_CIPHER(3DES_EDE_CBC_SHA)
 101
 102 static const int default_ciphersuites_nodhe[] =
 103 {
 104 #define TLS_CIPHER(v)                           \
 105         MBEDTLS_TLS_RSA_WITH_##v,
 106         TLS_DEFAULT_CIPHERS
 107 #undef TLS_CIPHER
 108         0
 109 };
 110
 111 static const int default_ciphersuites[] =
 112 {
 113 #define TLS_CIPHER(v)                           \
 114         MBEDTLS_TLS_DHE_RSA_WITH_##v,           \
 115         MBEDTLS_TLS_RSA_WITH_##v,
 116         TLS_DEFAULT_CIPHERS
 117 #undef TLS_CIPHER
 118         0
 119 };
 120
 121
 122 __hidden struct ustream_ssl_ctx *
 123 __ustream_ssl_context_new(bool server)
 124 {
 125         struct ustream_ssl_ctx *ctx;
 126         mbedtls_ssl_config *conf;
 127         int ep;
 128
 129         if (!urandom_init())
 130                 return NULL;
 131
 132         ctx = calloc(1, sizeof(*ctx));
 133         if (!ctx)
 134                 return NULL;
 135
 136         ctx->server = server;
 137         mbedtls_pk_init(&ctx->key);
 138         mbedtls_x509_crt_init(&ctx->cert);
 139         mbedtls_x509_crt_init(&ctx->ca_cert);
 140
 141 #if defined(MBEDTLS_SSL_CACHE_C)
 142         mbedtls_ssl_cache_init(&ctx->cache);
 143         mbedtls_ssl_cache_set_timeout(&ctx->cache, 30 * 60);
 144         mbedtls_ssl_cache_set_max_entries(&ctx->cache, 5);
 145 #endif
 146
 147         conf = &ctx->conf;
 148         mbedtls_ssl_config_init(conf);
 149
 150         if (server) {
 151                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites_nodhe);
 152                 ep = MBEDTLS_SSL_IS_SERVER;
 153         } else {
 154                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites);
 155                 ep = MBEDTLS_SSL_IS_CLIENT;
 156         }
 157
 158         mbedtls_ssl_config_defaults(conf, ep, MBEDTLS_SSL_TRANSPORT_STREAM,
 159                                     MBEDTLS_SSL_PRESET_DEFAULT);
 160         mbedtls_ssl_conf_authmode(conf, MBEDTLS_SSL_VERIFY_NONE);
 161         mbedtls_ssl_conf_rng(conf, _urandom, NULL);
 162
 163 #if defined(MBEDTLS_SSL_CACHE_C)
 164         mbedtls_ssl_conf_session_cache(conf, &ctx->cache,
 165                                        mbedtls_ssl_cache_get,
 166                                        mbedtls_ssl_cache_set);
 167 #endif
 168         return ctx;
 169 }
 170
 171 static void ustream_ssl_update_own_cert(struct ustream_ssl_ctx *ctx)
 172 {
 173         if (!ctx->cert.version)
 174                 return;
 175
 176         if (!ctx->server) {
 177                 mbedtls_ssl_conf_ca_chain(&ctx->conf, &ctx->cert, NULL);
 178                 return;
 179         }
 180
 181         if (!ctx->key.pk_info)
 182                 return;
 183
 184         if (ctx->cert.next)
 185                 mbedtls_ssl_conf_ca_chain(&ctx->conf, ctx->cert.next, NULL);
 186         mbedtls_ssl_conf_own_cert(&ctx->conf, &ctx->cert, &ctx->key);
 187 }
 188
 189 __hidden int __ustream_ssl_add_ca_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
 190 {
 191         int ret;
 192
 193         ret = mbedtls_x509_crt_parse_file(&ctx->ca_cert, file);
 194         if (ret)
 195                 return -1;
 196
 197         mbedtls_ssl_conf_ca_chain(&ctx->conf, &ctx->ca_cert, NULL);
 198         mbedtls_ssl_conf_authmode(&ctx->conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
 199         return 0;
 200 }
 201
 202 __hidden int __ustream_ssl_set_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
 203 {
 204         int ret;
 205
 206         ret = mbedtls_x509_crt_parse_file(&ctx->cert, file);
 207         if (ret)
 208                 return -1;
 209
 210         ustream_ssl_update_own_cert(ctx);
 211         return 0;
 212 }
 213
 214 __hidden int __ustream_ssl_set_key_file(struct ustream_ssl_ctx *ctx, const char *file)
 215 {
 216         int ret;
 217
 218         ret = mbedtls_pk_parse_keyfile(&ctx->key, file, NULL);
 219         if (ret)
 220                 return -1;
 221
 222         ustream_ssl_update_own_cert(ctx);
 223         return 0;
 224 }
 225
 226 __hidden void __ustream_ssl_context_free(struct ustream_ssl_ctx *ctx)
 227 {
 228 #if defined(MBEDTLS_SSL_CACHE_C)
 229         mbedtls_ssl_cache_free(&ctx->cache);
 230 #endif
 231         mbedtls_pk_free(&ctx->key);
 232         mbedtls_x509_crt_free(&ctx->ca_cert);
 233         mbedtls_x509_crt_free(&ctx->cert);
 234         mbedtls_ssl_config_free(&ctx->conf);
 235         free(ctx);
 236 }
 237
 238 static void ustream_ssl_error(struct ustream_ssl *us, int ret)
 239 {
 240         us->error = ret;
 241         uloop_timeout_set(&us->error_timer, 0);
 242 }
 243
 244 static bool ssl_do_wait(int ret)
 245 {
 246         switch(ret) {
 247         case MBEDTLS_ERR_SSL_WANT_READ:
 248         case MBEDTLS_ERR_SSL_WANT_WRITE:
 249                 return true;
 250         default:
 251                 return false;
 252         }
 253 }
 254
 255 static void ustream_ssl_verify_cert(struct ustream_ssl *us)
 256 {
 257         void *ssl = us->ssl;
 258         const char *msg = NULL;
 259         bool cn_mismatch;
 260         int r;
 261
 262         r = mbedtls_ssl_get_verify_result(ssl);
 263         cn_mismatch = r & MBEDTLS_X509_BADCERT_CN_MISMATCH;
 264         r &= ~MBEDTLS_X509_BADCERT_CN_MISMATCH;
 265
 266         if (r & MBEDTLS_X509_BADCERT_EXPIRED)
 267                 msg = "certificate has expired";
 268         else if (r & MBEDTLS_X509_BADCERT_REVOKED)
 269                 msg = "certificate has been revoked";
 270         else if (r & MBEDTLS_X509_BADCERT_NOT_TRUSTED)
 271                 msg = "certificate is self-signed or not signed by a trusted CA";
 272         else
 273                 msg = "unknown error";
 274
 275         if (r) {
 276                 if (us->notify_verify_error)
 277                         us->notify_verify_error(us, r, msg);
 278                 return;
 279         }
 280
 281         if (!cn_mismatch)
 282                 us->valid_cn = true;
 283 }
 284
 285 __hidden enum ssl_conn_status __ustream_ssl_connect(struct ustream_ssl *us)
 286 {
 287         void *ssl = us->ssl;
 288         int r;
 289
 290         r = mbedtls_ssl_handshake(ssl);
 291         if (r == 0) {
 292                 ustream_ssl_verify_cert(us);
 293                 return U_SSL_OK;
 294         }
 295
 296         if (ssl_do_wait(r))
 297                 return U_SSL_PENDING;
 298
 299         ustream_ssl_error(us, r);
 300         return U_SSL_ERROR;
 301 }
 302
 303 __hidden int __ustream_ssl_write(struct ustream_ssl *us, const char *buf, int len)
 304 {
 305         void *ssl = us->ssl;
 306         int done = 0, ret = 0;
 307
 308         while (done != len) {
 309                 ret = mbedtls_ssl_write(ssl, (const unsigned char *) buf + done, len - done);
 310
 311                 if (ret < 0) {
 312                         if (ssl_do_wait(ret))
 313                                 return done;
 314
 315                         ustream_ssl_error(us, ret);
 316                         return -1;
 317                 }
 318
 319                 done += ret;
 320         }
 321
 322         return done;
 323 }
 324
 325 __hidden int __ustream_ssl_read(struct ustream_ssl *us, char *buf, int len)
 326 {
 327         int ret = mbedtls_ssl_read(us->ssl, (unsigned char *) buf, len);
 328
 329         if (ret < 0) {
 330                 if (ssl_do_wait(ret))
 331                         return U_SSL_PENDING;
 332
 333                 if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY)
 334                         return 0;
 335
 336                 ustream_ssl_error(us, ret);
 337                 return U_SSL_ERROR;
 338         }
 339
 340         return ret;
 341 }
 342
 343 __hidden void *__ustream_ssl_session_new(struct ustream_ssl_ctx *ctx)
 344 {
 345         mbedtls_ssl_context *ssl;
 346
 347         ssl = calloc(1, sizeof(*ssl));
 348         if (!ssl)
 349                 return NULL;
 350
 351         mbedtls_ssl_init(ssl);
 352
 353         if (mbedtls_ssl_setup(ssl, &ctx->conf)) {
 354                 free(ssl);
 355                 return NULL;
 356         }
 357
 358         return ssl;
 359 }
 360
 361 __hidden void __ustream_ssl_session_free(void *ssl)
 362 {
 363         mbedtls_ssl_free(ssl);
 364         free(ssl);
 365 }