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_CIPHERS(v)                                  \
  90         MBEDTLS_TLS_##v##_WITH_AES_128_GCM_SHA256,      \
  91         MBEDTLS_TLS_##v##_WITH_AES_256_GCM_SHA384,      \
  92         MBEDTLS_TLS_##v##_WITH_AES_128_CBC_SHA,         \
  93         MBEDTLS_TLS_##v##_WITH_AES_256_CBC_SHA
  94
  95 static const int default_ciphersuites_server[] =
  96 {
  97         AES_CIPHERS(ECDHE_ECDSA),
  98         AES_CIPHERS(ECDHE_RSA),
  99         AES_CIPHERS(RSA),
 100         0
 101 };
 102
 103 static const int default_ciphersuites_client[] =
 104 {
 105         AES_CIPHERS(ECDHE_ECDSA),
 106         AES_CIPHERS(ECDHE_RSA),
 107         AES_CIPHERS(DHE_RSA),
 108         MBEDTLS_TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA,
 109         AES_CIPHERS(RSA),
 110         MBEDTLS_TLS_RSA_WITH_3DES_EDE_CBC_SHA,
 111         0
 112 };
 113
 114
 115 __hidden struct ustream_ssl_ctx *
 116 __ustream_ssl_context_new(bool server)
 117 {
 118         struct ustream_ssl_ctx *ctx;
 119         mbedtls_ssl_config *conf;
 120         int ep;
 121
 122         if (!urandom_init())
 123                 return NULL;
 124
 125         ctx = calloc(1, sizeof(*ctx));
 126         if (!ctx)
 127                 return NULL;
 128
 129         ctx->server = server;
 130         mbedtls_pk_init(&ctx->key);
 131         mbedtls_x509_crt_init(&ctx->cert);
 132         mbedtls_x509_crt_init(&ctx->ca_cert);
 133
 134 #if defined(MBEDTLS_SSL_CACHE_C)
 135         mbedtls_ssl_cache_init(&ctx->cache);
 136         mbedtls_ssl_cache_set_timeout(&ctx->cache, 30 * 60);
 137         mbedtls_ssl_cache_set_max_entries(&ctx->cache, 5);
 138 #endif
 139
 140         conf = &ctx->conf;
 141         mbedtls_ssl_config_init(conf);
 142
 143         ep = server ? MBEDTLS_SSL_IS_SERVER : MBEDTLS_SSL_IS_CLIENT;
 144
 145         mbedtls_ssl_config_defaults(conf, ep, MBEDTLS_SSL_TRANSPORT_STREAM,
 146                                     MBEDTLS_SSL_PRESET_DEFAULT);
 147         mbedtls_ssl_conf_authmode(conf, MBEDTLS_SSL_VERIFY_NONE);
 148         mbedtls_ssl_conf_rng(conf, _urandom, NULL);
 149
 150         if (server) {
 151                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites_server);
 152                 mbedtls_ssl_conf_min_version(conf, MBEDTLS_SSL_MAJOR_VERSION_3,
 153                                              MBEDTLS_SSL_MINOR_VERSION_3);
 154         } else
 155                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites_client);
 156
 157 #if defined(MBEDTLS_SSL_CACHE_C)
 158         mbedtls_ssl_conf_session_cache(conf, &ctx->cache,
 159                                        mbedtls_ssl_cache_get,
 160                                        mbedtls_ssl_cache_set);
 161 #endif
 162         return ctx;
 163 }
 164
 165 static void ustream_ssl_update_own_cert(struct ustream_ssl_ctx *ctx)
 166 {
 167         if (!ctx->cert.version)
 168                 return;
 169
 170         if (!ctx->server) {
 171                 mbedtls_ssl_conf_ca_chain(&ctx->conf, &ctx->cert, NULL);
 172                 return;
 173         }
 174
 175         if (!ctx->key.pk_info)
 176                 return;
 177
 178         if (ctx->cert.next)
 179                 mbedtls_ssl_conf_ca_chain(&ctx->conf, ctx->cert.next, NULL);
 180         mbedtls_ssl_conf_own_cert(&ctx->conf, &ctx->cert, &ctx->key);
 181 }
 182
 183 __hidden int __ustream_ssl_add_ca_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
 184 {
 185         int ret;
 186
 187         ret = mbedtls_x509_crt_parse_file(&ctx->ca_cert, file);
 188         if (ret)
 189                 return -1;
 190
 191         mbedtls_ssl_conf_ca_chain(&ctx->conf, &ctx->ca_cert, NULL);
 192         mbedtls_ssl_conf_authmode(&ctx->conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
 193         return 0;
 194 }
 195
 196 __hidden int __ustream_ssl_set_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
 197 {
 198         int ret;
 199
 200         ret = mbedtls_x509_crt_parse_file(&ctx->cert, file);
 201         if (ret)
 202                 return -1;
 203
 204         ustream_ssl_update_own_cert(ctx);
 205         return 0;
 206 }
 207
 208 __hidden int __ustream_ssl_set_key_file(struct ustream_ssl_ctx *ctx, const char *file)
 209 {
 210         int ret;
 211
 212         ret = mbedtls_pk_parse_keyfile(&ctx->key, file, NULL);
 213         if (ret)
 214                 return -1;
 215
 216         ustream_ssl_update_own_cert(ctx);
 217         return 0;
 218 }
 219
 220 __hidden void __ustream_ssl_context_free(struct ustream_ssl_ctx *ctx)
 221 {
 222 #if defined(MBEDTLS_SSL_CACHE_C)
 223         mbedtls_ssl_cache_free(&ctx->cache);
 224 #endif
 225         mbedtls_pk_free(&ctx->key);
 226         mbedtls_x509_crt_free(&ctx->ca_cert);
 227         mbedtls_x509_crt_free(&ctx->cert);
 228         mbedtls_ssl_config_free(&ctx->conf);
 229         free(ctx);
 230 }
 231
 232 static void ustream_ssl_error(struct ustream_ssl *us, int ret)
 233 {
 234         us->error = ret;
 235         uloop_timeout_set(&us->error_timer, 0);
 236 }
 237
 238 static bool ssl_do_wait(int ret)
 239 {
 240         switch(ret) {
 241         case MBEDTLS_ERR_SSL_WANT_READ:
 242         case MBEDTLS_ERR_SSL_WANT_WRITE:
 243                 return true;
 244         default:
 245                 return false;
 246         }
 247 }
 248
 249 static void ustream_ssl_verify_cert(struct ustream_ssl *us)
 250 {
 251         void *ssl = us->ssl;
 252         const char *msg = NULL;
 253         bool cn_mismatch;
 254         int r;
 255
 256         r = mbedtls_ssl_get_verify_result(ssl);
 257         cn_mismatch = r & MBEDTLS_X509_BADCERT_CN_MISMATCH;
 258         r &= ~MBEDTLS_X509_BADCERT_CN_MISMATCH;
 259
 260         if (r & MBEDTLS_X509_BADCERT_EXPIRED)
 261                 msg = "certificate has expired";
 262         else if (r & MBEDTLS_X509_BADCERT_REVOKED)
 263                 msg = "certificate has been revoked";
 264         else if (r & MBEDTLS_X509_BADCERT_NOT_TRUSTED)
 265                 msg = "certificate is self-signed or not signed by a trusted CA";
 266         else
 267                 msg = "unknown error";
 268
 269         if (r) {
 270                 if (us->notify_verify_error)
 271                         us->notify_verify_error(us, r, msg);
 272                 return;
 273         }
 274
 275         if (!cn_mismatch)
 276                 us->valid_cn = true;
 277 }
 278
 279 __hidden enum ssl_conn_status __ustream_ssl_connect(struct ustream_ssl *us)
 280 {
 281         void *ssl = us->ssl;
 282         int r;
 283
 284         r = mbedtls_ssl_handshake(ssl);
 285         if (r == 0) {
 286                 ustream_ssl_verify_cert(us);
 287                 return U_SSL_OK;
 288         }
 289
 290         if (ssl_do_wait(r))
 291                 return U_SSL_PENDING;
 292
 293         ustream_ssl_error(us, r);
 294         return U_SSL_ERROR;
 295 }
 296
 297 __hidden int __ustream_ssl_write(struct ustream_ssl *us, const char *buf, int len)
 298 {
 299         void *ssl = us->ssl;
 300         int done = 0, ret = 0;
 301
 302         while (done != len) {
 303                 ret = mbedtls_ssl_write(ssl, (const unsigned char *) buf + done, len - done);
 304
 305                 if (ret < 0) {
 306                         if (ssl_do_wait(ret))
 307                                 return done;
 308
 309                         ustream_ssl_error(us, ret);
 310                         return -1;
 311                 }
 312
 313                 done += ret;
 314         }
 315
 316         return done;
 317 }
 318
 319 __hidden int __ustream_ssl_read(struct ustream_ssl *us, char *buf, int len)
 320 {
 321         int ret = mbedtls_ssl_read(us->ssl, (unsigned char *) buf, len);
 322
 323         if (ret < 0) {
 324                 if (ssl_do_wait(ret))
 325                         return U_SSL_PENDING;
 326
 327                 if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY)
 328                         return 0;
 329
 330                 ustream_ssl_error(us, ret);
 331                 return U_SSL_ERROR;
 332         }
 333
 334         return ret;
 335 }
 336
 337 __hidden void *__ustream_ssl_session_new(struct ustream_ssl_ctx *ctx)
 338 {
 339         mbedtls_ssl_context *ssl;
 340
 341         ssl = calloc(1, sizeof(*ssl));
 342         if (!ssl)
 343                 return NULL;
 344
 345         mbedtls_ssl_init(ssl);
 346
 347         if (mbedtls_ssl_setup(ssl, &ctx->conf)) {
 348                 free(ssl);
 349                 return NULL;
 350         }
 351
 352         return ssl;
 353 }
 354
 355 __hidden void __ustream_ssl_session_free(void *ssl)
 356 {
 357         mbedtls_ssl_free(ssl);
 358         free(ssl);
 359 }