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         MBEDTLS_TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256,
  98         AES_CIPHERS(ECDHE_ECDSA),
  99         MBEDTLS_TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
 100         AES_CIPHERS(ECDHE_RSA),
 101         AES_CIPHERS(RSA),
 102         0
 103 };
 104
 105 static const int default_ciphersuites_client[] =
 106 {
 107         MBEDTLS_TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256,
 108         AES_CIPHERS(ECDHE_ECDSA),
 109         MBEDTLS_TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
 110         AES_CIPHERS(ECDHE_RSA),
 111         MBEDTLS_TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
 112         AES_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         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_server);
 157                 mbedtls_ssl_conf_min_version(conf, MBEDTLS_SSL_MAJOR_VERSION_3,
 158                                              MBEDTLS_SSL_MINOR_VERSION_3);
 159         } else
 160                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites_client);
 161
 162 #if defined(MBEDTLS_SSL_CACHE_C)
 163         mbedtls_ssl_conf_session_cache(conf, &ctx->cache,
 164                                        mbedtls_ssl_cache_get,
 165                                        mbedtls_ssl_cache_set);
 166 #endif
 167         return ctx;
 168 }
 169
 170 static void ustream_ssl_update_own_cert(struct ustream_ssl_ctx *ctx)
 171 {
 172         if (!ctx->cert.version)
 173                 return;
 174
 175         if (!ctx->server) {
 176                 mbedtls_ssl_conf_ca_chain(&ctx->conf, &ctx->cert, NULL);
 177                 return;
 178         }
 179
 180         if (!ctx->key.pk_info)
 181                 return;
 182
 183         if (ctx->cert.next)
 184                 mbedtls_ssl_conf_ca_chain(&ctx->conf, ctx->cert.next, NULL);
 185         mbedtls_ssl_conf_own_cert(&ctx->conf, &ctx->cert, &ctx->key);
 186 }
 187
 188 __hidden int __ustream_ssl_add_ca_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
 189 {
 190         int ret;
 191
 192         ret = mbedtls_x509_crt_parse_file(&ctx->ca_cert, file);
 193         if (ret)
 194                 return -1;
 195
 196         mbedtls_ssl_conf_ca_chain(&ctx->conf, &ctx->ca_cert, NULL);
 197         mbedtls_ssl_conf_authmode(&ctx->conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
 198         return 0;
 199 }
 200
 201 __hidden int __ustream_ssl_set_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
 202 {
 203         int ret;
 204
 205         ret = mbedtls_x509_crt_parse_file(&ctx->cert, file);
 206         if (ret)
 207                 return -1;
 208
 209         ustream_ssl_update_own_cert(ctx);
 210         return 0;
 211 }
 212
 213 __hidden int __ustream_ssl_set_key_file(struct ustream_ssl_ctx *ctx, const char *file)
 214 {
 215         int ret;
 216
 217         ret = mbedtls_pk_parse_keyfile(&ctx->key, file, NULL);
 218         if (ret)
 219                 return -1;
 220
 221         ustream_ssl_update_own_cert(ctx);
 222         return 0;
 223 }
 224
 225 __hidden void __ustream_ssl_context_free(struct ustream_ssl_ctx *ctx)
 226 {
 227 #if defined(MBEDTLS_SSL_CACHE_C)
 228         mbedtls_ssl_cache_free(&ctx->cache);
 229 #endif
 230         mbedtls_pk_free(&ctx->key);
 231         mbedtls_x509_crt_free(&ctx->ca_cert);
 232         mbedtls_x509_crt_free(&ctx->cert);
 233         mbedtls_ssl_config_free(&ctx->conf);
 234         free(ctx);
 235 }
 236
 237 static void ustream_ssl_error(struct ustream_ssl *us, int ret)
 238 {
 239         us->error = ret;
 240         uloop_timeout_set(&us->error_timer, 0);
 241 }
 242
 243 static bool ssl_do_wait(int ret)
 244 {
 245         switch(ret) {
 246         case MBEDTLS_ERR_SSL_WANT_READ:
 247         case MBEDTLS_ERR_SSL_WANT_WRITE:
 248                 return true;
 249         default:
 250                 return false;
 251         }
 252 }
 253
 254 static void ustream_ssl_verify_cert(struct ustream_ssl *us)
 255 {
 256         void *ssl = us->ssl;
 257         const char *msg = NULL;
 258         bool cn_mismatch;
 259         int r;
 260
 261         r = mbedtls_ssl_get_verify_result(ssl);
 262         cn_mismatch = r & MBEDTLS_X509_BADCERT_CN_MISMATCH;
 263         r &= ~MBEDTLS_X509_BADCERT_CN_MISMATCH;
 264
 265         if (r & MBEDTLS_X509_BADCERT_EXPIRED)
 266                 msg = "certificate has expired";
 267         else if (r & MBEDTLS_X509_BADCERT_REVOKED)
 268                 msg = "certificate has been revoked";
 269         else if (r & MBEDTLS_X509_BADCERT_NOT_TRUSTED)
 270                 msg = "certificate is self-signed or not signed by a trusted CA";
 271         else
 272                 msg = "unknown error";
 273
 274         if (r) {
 275                 if (us->notify_verify_error)
 276                         us->notify_verify_error(us, r, msg);
 277                 return;
 278         }
 279
 280         if (!cn_mismatch)
 281                 us->valid_cn = true;
 282 }
 283
 284 __hidden enum ssl_conn_status __ustream_ssl_connect(struct ustream_ssl *us)
 285 {
 286         void *ssl = us->ssl;
 287         int r;
 288
 289         r = mbedtls_ssl_handshake(ssl);
 290         if (r == 0) {
 291                 ustream_ssl_verify_cert(us);
 292                 return U_SSL_OK;
 293         }
 294
 295         if (ssl_do_wait(r))
 296                 return U_SSL_PENDING;
 297
 298         ustream_ssl_error(us, r);
 299         return U_SSL_ERROR;
 300 }
 301
 302 __hidden int __ustream_ssl_write(struct ustream_ssl *us, const char *buf, int len)
 303 {
 304         void *ssl = us->ssl;
 305         int done = 0, ret = 0;
 306
 307         while (done != len) {
 308                 ret = mbedtls_ssl_write(ssl, (const unsigned char *) buf + done, len - done);
 309
 310                 if (ret < 0) {
 311                         if (ssl_do_wait(ret))
 312                                 return done;
 313
 314                         ustream_ssl_error(us, ret);
 315                         return -1;
 316                 }
 317
 318                 done += ret;
 319         }
 320
 321         return done;
 322 }
 323
 324 __hidden int __ustream_ssl_read(struct ustream_ssl *us, char *buf, int len)
 325 {
 326         int ret = mbedtls_ssl_read(us->ssl, (unsigned char *) buf, len);
 327
 328         if (ret < 0) {
 329                 if (ssl_do_wait(ret))
 330                         return U_SSL_PENDING;
 331
 332                 if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY)
 333                         return 0;
 334
 335                 ustream_ssl_error(us, ret);
 336                 return U_SSL_ERROR;
 337         }
 338
 339         return ret;
 340 }
 341
 342 __hidden void *__ustream_ssl_session_new(struct ustream_ssl_ctx *ctx)
 343 {
 344         mbedtls_ssl_context *ssl;
 345
 346         ssl = calloc(1, sizeof(*ssl));
 347         if (!ssl)
 348                 return NULL;
 349
 350         mbedtls_ssl_init(ssl);
 351
 352         if (mbedtls_ssl_setup(ssl, &ctx->conf)) {
 353                 free(ssl);
 354                 return NULL;
 355         }
 356
 357         return ssl;
 358 }
 359
 360 __hidden void __ustream_ssl_session_free(void *ssl)
 361 {
 362         mbedtls_ssl_free(ssl);
 363         free(ssl);
 364 }