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         conf = &ctx->conf;
 142         mbedtls_ssl_config_init(conf);
 143
 144         if (server) {
 145                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites_nodhe);
 146                 ep = MBEDTLS_SSL_IS_SERVER;
 147         } else {
 148                 mbedtls_ssl_conf_ciphersuites(conf, default_ciphersuites);
 149                 ep = MBEDTLS_SSL_IS_CLIENT;
 150         }
 151
 152         mbedtls_ssl_config_defaults(conf, ep, MBEDTLS_SSL_TRANSPORT_STREAM,
 153                                     MBEDTLS_SSL_PRESET_DEFAULT);
 154         mbedtls_ssl_conf_authmode(conf, MBEDTLS_SSL_VERIFY_NONE);
 155         mbedtls_ssl_conf_rng(conf, _urandom, NULL);
 156
 157         return ctx;
 158 }
 159
 160 static void ustream_ssl_update_own_cert(struct ustream_ssl_ctx *ctx)
 161 {
 162         if (!ctx->cert.version)
 163                 return;
 164
 165         if (!ctx->server) {
 166                 mbedtls_ssl_conf_ca_chain(&ctx->conf, &ctx->cert, NULL);
 167                 return;
 168         }
 169
 170         if (!ctx->key.pk_info)
 171                 return;
 172
 173         if (ctx->cert.next)
 174                 mbedtls_ssl_conf_ca_chain(&ctx->conf, ctx->cert.next, NULL);
 175         mbedtls_ssl_conf_own_cert(&ctx->conf, &ctx->cert, &ctx->key);
 176 }
 177
 178 __hidden int __ustream_ssl_add_ca_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
 179 {
 180         int ret;
 181
 182         ret = mbedtls_x509_crt_parse_file(&ctx->ca_cert, file);
 183         if (ret)
 184                 return -1;
 185
 186         mbedtls_ssl_conf_ca_chain(&ctx->conf, &ctx->ca_cert, NULL);
 187         mbedtls_ssl_conf_authmode(&ctx->conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
 188         return 0;
 189 }
 190
 191 __hidden int __ustream_ssl_set_crt_file(struct ustream_ssl_ctx *ctx, const char *file)
 192 {
 193         int ret;
 194
 195         ret = mbedtls_x509_crt_parse_file(&ctx->cert, file);
 196         if (ret)
 197                 return -1;
 198
 199         ustream_ssl_update_own_cert(ctx);
 200         return 0;
 201 }
 202
 203 __hidden int __ustream_ssl_set_key_file(struct ustream_ssl_ctx *ctx, const char *file)
 204 {
 205         int ret;
 206
 207         ret = mbedtls_pk_parse_keyfile(&ctx->key, file, NULL);
 208         if (ret)
 209                 return -1;
 210
 211         ustream_ssl_update_own_cert(ctx);
 212         return 0;
 213 }
 214
 215 __hidden void __ustream_ssl_context_free(struct ustream_ssl_ctx *ctx)
 216 {
 217         mbedtls_pk_free(&ctx->key);
 218         mbedtls_x509_crt_free(&ctx->ca_cert);
 219         mbedtls_x509_crt_free(&ctx->cert);
 220         mbedtls_ssl_config_free(&ctx->conf);
 221         free(ctx);
 222 }
 223
 224 static void ustream_ssl_error(struct ustream_ssl *us, int ret)
 225 {
 226         us->error = ret;
 227         uloop_timeout_set(&us->error_timer, 0);
 228 }
 229
 230 static bool ssl_do_wait(int ret)
 231 {
 232         switch(ret) {
 233         case MBEDTLS_ERR_SSL_WANT_READ:
 234         case MBEDTLS_ERR_SSL_WANT_WRITE:
 235                 return true;
 236         default:
 237                 return false;
 238         }
 239 }
 240
 241 static void ustream_ssl_verify_cert(struct ustream_ssl *us)
 242 {
 243         void *ssl = us->ssl;
 244         const char *msg = NULL;
 245         bool cn_mismatch;
 246         int r;
 247
 248         r = mbedtls_ssl_get_verify_result(ssl);
 249         cn_mismatch = r & MBEDTLS_X509_BADCERT_CN_MISMATCH;
 250         r &= ~MBEDTLS_X509_BADCERT_CN_MISMATCH;
 251
 252         if (r & MBEDTLS_X509_BADCERT_EXPIRED)
 253                 msg = "certificate has expired";
 254         else if (r & MBEDTLS_X509_BADCERT_REVOKED)
 255                 msg = "certificate has been revoked";
 256         else if (r & MBEDTLS_X509_BADCERT_NOT_TRUSTED)
 257                 msg = "certificate is self-signed or not signed by a trusted CA";
 258         else
 259                 msg = "unknown error";
 260
 261         if (r) {
 262                 if (us->notify_verify_error)
 263                         us->notify_verify_error(us, r, msg);
 264                 return;
 265         }
 266
 267         if (!cn_mismatch)
 268                 us->valid_cn = true;
 269 }
 270
 271 __hidden enum ssl_conn_status __ustream_ssl_connect(struct ustream_ssl *us)
 272 {
 273         void *ssl = us->ssl;
 274         int r;
 275
 276         r = mbedtls_ssl_handshake(ssl);
 277         if (r == 0) {
 278                 ustream_ssl_verify_cert(us);
 279                 return U_SSL_OK;
 280         }
 281
 282         if (ssl_do_wait(r))
 283                 return U_SSL_PENDING;
 284
 285         ustream_ssl_error(us, r);
 286         return U_SSL_ERROR;
 287 }
 288
 289 __hidden int __ustream_ssl_write(struct ustream_ssl *us, const char *buf, int len)
 290 {
 291         void *ssl = us->ssl;
 292         int done = 0, ret = 0;
 293
 294         while (done != len) {
 295                 ret = mbedtls_ssl_write(ssl, (const unsigned char *) buf + done, len - done);
 296
 297                 if (ret < 0) {
 298                         if (ssl_do_wait(ret))
 299                                 return done;
 300
 301                         ustream_ssl_error(us, ret);
 302                         return -1;
 303                 }
 304
 305                 done += ret;
 306         }
 307
 308         return done;
 309 }
 310
 311 __hidden int __ustream_ssl_read(struct ustream_ssl *us, char *buf, int len)
 312 {
 313         int ret = mbedtls_ssl_read(us->ssl, (unsigned char *) buf, len);
 314
 315         if (ret < 0) {
 316                 if (ssl_do_wait(ret))
 317                         return U_SSL_PENDING;
 318
 319                 if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY)
 320                         return 0;
 321
 322                 ustream_ssl_error(us, ret);
 323                 return U_SSL_ERROR;
 324         }
 325
 326         return ret;
 327 }
 328
 329 __hidden void *__ustream_ssl_session_new(struct ustream_ssl_ctx *ctx)
 330 {
 331         mbedtls_ssl_context *ssl;
 332
 333         ssl = calloc(1, sizeof(*ssl));
 334         if (!ssl)
 335                 return NULL;
 336
 337         mbedtls_ssl_init(ssl);
 338
 339         if (mbedtls_ssl_setup(ssl, &ctx->conf)) {
 340                 free(ssl);
 341                 return NULL;
 342         }
 343
 344         return ssl;
 345 }
 346
 347 __hidden void __ustream_ssl_session_free(void *ssl)
 348 {
 349         mbedtls_ssl_free(ssl);
 350         free(ssl);
 351 }