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_128_GCM_SHA256)              \
  91     TLS_CIPHER(AES_256_GCM_SHA384)              \
  92     TLS_CIPHER(AES_128_CBC_SHA)                 \
  93     TLS_CIPHER(AES_256_CBC_SHA)                 \
  94     TLS_CIPHER(3DES_EDE_CBC_SHA)
  95
  96 static const int default_ciphersuites_nodhe[] =
  97 {
  98 #define TLS_CIPHER(v)                           \
  99         MBEDTLS_TLS_ECDHE_ECDSA_WITH_##v,       \
 100         MBEDTLS_TLS_ECDHE_RSA_WITH_##v,         \
 101         MBEDTLS_TLS_RSA_WITH_##v,
 102         TLS_DEFAULT_CIPHERS
 103 #undef TLS_CIPHER
 104         0
 105 };
 106
 107 static const int default_ciphersuites[] =
 108 {
 109 #define TLS_CIPHER(v)                           \
 110         MBEDTLS_TLS_ECDHE_ECDSA_WITH_##v,       \
 111         MBEDTLS_TLS_ECDHE_RSA_WITH_##v,         \
 112         MBEDTLS_TLS_DHE_RSA_WITH_##v,           \
 113         MBEDTLS_TLS_RSA_WITH_##v,
 114         TLS_DEFAULT_CIPHERS
 115 #undef TLS_CIPHER
 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         if (!urandom_init())
 128                 return NULL;
 129
 130         ctx = calloc(1, sizeof(*ctx));
 131         if (!ctx)
 132                 return NULL;
 133
 134         ctx->server = server;
 135         mbedtls_pk_init(&ctx->key);
 136         mbedtls_x509_crt_init(&ctx->cert);
 137         mbedtls_x509_crt_init(&ctx->ca_cert);
 138
 139 #if defined(MBEDTLS_SSL_CACHE_C)
 140         mbedtls_ssl_cache_init(&ctx->cache);
 141         mbedtls_ssl_cache_set_timeout(&ctx->cache, 30 * 60);
 142         mbedtls_ssl_cache_set_max_entries(&ctx->cache, 5);
 143 #endif
 144
 145         conf = &ctx->conf;
 146         mbedtls_ssl_config_init(conf);
 147
 148         ep = server ? MBEDTLS_SSL_IS_SERVER : MBEDTLS_SSL_IS_CLIENT;
 149
 150         mbedtls_ssl_config_defaults(conf, ep, MBEDTLS_SSL_TRANSPORT_STREAM,
 151                                     MBEDTLS_SSL_PRESET_DEFAULT);
 152         mbedtls_ssl_conf_authmode(conf, MBEDTLS_SSL_VERIFY_NONE);
 153         mbedtls_ssl_conf_rng(conf, _urandom, NULL);
 154
 155         if (server)
 156                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites_nodhe);
 157         else
 158                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites);
 159
 160 #if defined(MBEDTLS_SSL_CACHE_C)
 161         mbedtls_ssl_conf_session_cache(conf, &ctx->cache,
 162                                        mbedtls_ssl_cache_get,
 163                                        mbedtls_ssl_cache_set);
 164 #endif
 165         return ctx;
 166 }
 167
 168 static void ustream_ssl_update_own_cert(struct ustream_ssl_ctx *ctx)
 169 {
 170         if (!ctx->cert.version)
 171                 return;
 172
 173         if (!ctx->server) {
 174                 mbedtls_ssl_conf_ca_chain(&ctx->conf, &ctx->cert, NULL);
 175                 return;
 176         }
 177
 178         if (!ctx->key.pk_info)
 179                 return;
 180
 181         if (ctx->cert.next)
 182                 mbedtls_ssl_conf_ca_chain(&ctx->conf, ctx->cert.next, NULL);
 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         ret = mbedtls_pk_parse_keyfile(&ctx->key, file, NULL);
 216         if (ret)
 217                 return -1;
 218
 219         ustream_ssl_update_own_cert(ctx);
 220         return 0;
 221 }
 222
 223 __hidden void __ustream_ssl_context_free(struct ustream_ssl_ctx *ctx)
 224 {
 225 #if defined(MBEDTLS_SSL_CACHE_C)
 226         mbedtls_ssl_cache_free(&ctx->cache);
 227 #endif
 228         mbedtls_pk_free(&ctx->key);
 229         mbedtls_x509_crt_free(&ctx->ca_cert);
 230         mbedtls_x509_crt_free(&ctx->cert);
 231         mbedtls_ssl_config_free(&ctx->conf);
 232         free(ctx);
 233 }
 234
 235 static void ustream_ssl_error(struct ustream_ssl *us, int ret)
 236 {
 237         us->error = ret;
 238         uloop_timeout_set(&us->error_timer, 0);
 239 }
 240
 241 static bool ssl_do_wait(int ret)
 242 {
 243         switch(ret) {
 244         case MBEDTLS_ERR_SSL_WANT_READ:
 245         case MBEDTLS_ERR_SSL_WANT_WRITE:
 246                 return true;
 247         default:
 248                 return false;
 249         }
 250 }
 251
 252 static void ustream_ssl_verify_cert(struct ustream_ssl *us)
 253 {
 254         void *ssl = us->ssl;
 255         const char *msg = NULL;
 256         bool cn_mismatch;
 257         int r;
 258
 259         r = mbedtls_ssl_get_verify_result(ssl);
 260         cn_mismatch = r & MBEDTLS_X509_BADCERT_CN_MISMATCH;
 261         r &= ~MBEDTLS_X509_BADCERT_CN_MISMATCH;
 262
 263         if (r & MBEDTLS_X509_BADCERT_EXPIRED)
 264                 msg = "certificate has expired";
 265         else if (r & MBEDTLS_X509_BADCERT_REVOKED)
 266                 msg = "certificate has been revoked";
 267         else if (r & MBEDTLS_X509_BADCERT_NOT_TRUSTED)
 268                 msg = "certificate is self-signed or not signed by a trusted CA";
 269         else
 270                 msg = "unknown error";
 271
 272         if (r) {
 273                 if (us->notify_verify_error)
 274                         us->notify_verify_error(us, r, msg);
 275                 return;
 276         }
 277
 278         if (!cn_mismatch)
 279                 us->valid_cn = true;
 280 }
 281
 282 __hidden enum ssl_conn_status __ustream_ssl_connect(struct ustream_ssl *us)
 283 {
 284         void *ssl = us->ssl;
 285         int r;
 286
 287         r = mbedtls_ssl_handshake(ssl);
 288         if (r == 0) {
 289                 ustream_ssl_verify_cert(us);
 290                 return U_SSL_OK;
 291         }
 292
 293         if (ssl_do_wait(r))
 294                 return U_SSL_PENDING;
 295
 296         ustream_ssl_error(us, r);
 297         return U_SSL_ERROR;
 298 }
 299
 300 __hidden int __ustream_ssl_write(struct ustream_ssl *us, const char *buf, int len)
 301 {
 302         void *ssl = us->ssl;
 303         int done = 0, ret = 0;
 304
 305         while (done != len) {
 306                 ret = mbedtls_ssl_write(ssl, (const unsigned char *) buf + done, len - done);
 307
 308                 if (ret < 0) {
 309                         if (ssl_do_wait(ret))
 310                                 return done;
 311
 312                         ustream_ssl_error(us, ret);
 313                         return -1;
 314                 }
 315
 316                 done += ret;
 317         }
 318
 319         return done;
 320 }
 321
 322 __hidden int __ustream_ssl_read(struct ustream_ssl *us, char *buf, int len)
 323 {
 324         int ret = mbedtls_ssl_read(us->ssl, (unsigned char *) buf, len);
 325
 326         if (ret < 0) {
 327                 if (ssl_do_wait(ret))
 328                         return U_SSL_PENDING;
 329
 330                 if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY)
 331                         return 0;
 332
 333                 ustream_ssl_error(us, ret);
 334                 return U_SSL_ERROR;
 335         }
 336
 337         return ret;
 338 }
 339
 340 __hidden void *__ustream_ssl_session_new(struct ustream_ssl_ctx *ctx)
 341 {
 342         mbedtls_ssl_context *ssl;
 343
 344         ssl = calloc(1, sizeof(*ssl));
 345         if (!ssl)
 346                 return NULL;
 347
 348         mbedtls_ssl_init(ssl);
 349
 350         if (mbedtls_ssl_setup(ssl, &ctx->conf)) {
 351                 free(ssl);
 352                 return NULL;
 353         }
 354
 355         return ssl;
 356 }
 357
 358 __hidden void __ustream_ssl_session_free(void *ssl)
 359 {
 360         mbedtls_ssl_free(ssl);
 361         free(ssl);
 362 }