The Tcpdump Group git mirrors - libpcap/blob - sslutils.c

   1 /*
   2  * Copyright (c) 2002 - 2003
   3  * NetGroup, Politecnico di Torino (Italy)
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  * notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  * notice, this list of conditions and the following disclaimer in the
  14  * documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the Politecnico di Torino nor the names of its
  16  * contributors may be used to endorse or promote products derived from
  17  * this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  20  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  21  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  22  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  23  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  27  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  29  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  30  *
  31  */
  32
  33 #ifdef HAVE_CONFIG_H
  34 #include <config.h>
  35 #endif
  36
  37 #ifdef HAVE_OPENSSL
  38 #include <stdlib.h>
  39
  40 #include "portability.h"
  41
  42 #include "sslutils.h"
  43
  44 static const char *ssl_keyfile = "";   //!< file containing the private key in PEM format
  45 static const char *ssl_certfile = "";  //!< file containing the server's certificate in PEM format
  46 static const char *ssl_rootfile = "";  //!< file containing the list of CAs trusted by the client
  47 // TODO: a way to set ssl_rootfile from the command line, or an envvar?
  48
  49 // TODO: lock?
  50 static SSL_CTX *ctx;
  51
  52 void ssl_set_certfile(const char *certfile)
  53 {
  54         ssl_certfile = certfile;
  55 }
  56
  57 void ssl_set_keyfile(const char *keyfile)
  58 {
  59         ssl_keyfile = keyfile;
  60 }
  61
  62 int ssl_init_once(int is_server, int enable_compression, char *errbuf, size_t errbuflen)
  63 {
  64         static int inited = 0;
  65         if (inited) return 0;
  66
  67         /*
  68          * Avoid deprecated routines, even if they're still documented,
  69          * as random versions of OpenSSL might not make them available.
  70          * XXX - what's the minimum OpenSSL version we should support?
  71          * And what about libressl?
  72          */
  73 #if defined(OPENSSL_VERSION_NUMBER) >= 0x10100000L
  74         /* 1.1.0 or later */
  75         OPENSSL_init_ssl(0, NULL);
  76         OPENSSL_init_ssl(OPENSSL_INIT_LOAD_SSL_STRINGS | OPENSSL_INIT_LOAD_CRYPTO_STRINGS, NULL);
  77 #else
  78         SSL_library_init();
  79         SSL_load_error_strings();
  80 #endif
  81         OpenSSL_add_ssl_algorithms();
  82         if (enable_compression)
  83                 SSL_COMP_get_compression_methods();
  84
  85 #if defined(OPENSSL_VERSION_NUMBER) >= 0x10100000L
  86         /* 1.1.0 or later */
  87         SSL_METHOD const *meth =
  88             is_server ? TLS_server_method() : TLS_client_method();
  89 #else
  90         SSL_METHOD const *meth =
  91             is_server ? SSLv23_server_method() : SSLv23_client_method();
  92 #endif
  93         ctx = SSL_CTX_new(meth);
  94         if (! ctx)
  95         {
  96                 snprintf(errbuf, errbuflen, "Cannot get a new SSL context: %s", ERR_error_string(ERR_get_error(), NULL));
  97                 goto die;
  98         }
  99
 100         SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
 101
 102         if (is_server)
 103         {
 104                 char const *certfile = ssl_certfile[0] ? ssl_certfile : "cert.pem";
 105                 if (1 != SSL_CTX_use_certificate_file(ctx, certfile, SSL_FILETYPE_PEM))
 106                 {
 107                         snprintf(errbuf, errbuflen, "Cannot read certificate file %s: %s", certfile, ERR_error_string(ERR_get_error(), NULL));
 108                         goto die;
 109                 }
 110
 111                 char const *keyfile = ssl_keyfile[0] ? ssl_keyfile : "key.pem";
 112                 if (1 != SSL_CTX_use_PrivateKey_file(ctx, keyfile, SSL_FILETYPE_PEM))
 113                 {
 114                         snprintf(errbuf, errbuflen, "Cannot read private key file %s: %s", keyfile, ERR_error_string(ERR_get_error(), NULL));
 115                         goto die;
 116                 }
 117         }
 118         else
 119         {
 120                 if (ssl_rootfile[0])
 121                 {
 122                         if (! SSL_CTX_load_verify_locations(ctx, ssl_rootfile, 0))
 123                         {
 124                                 snprintf(errbuf, errbuflen, "Cannot read CA list from %s", ssl_rootfile);
 125                                 goto die;
 126                         }
 127                 }
 128                 else
 129                 {
 130                         SSL_CTX_set_verify(ctx, SSL_VERIFY_NONE, NULL);
 131                 }
 132         }
 133
 134 #if 0
 135         if (! RAND_load_file(RANDOM, 1024*1024))
 136         {
 137                 snprintf(errbuf, errbuflen, "Cannot init random");
 138                 goto die;
 139         }
 140
 141         if (is_server)
 142         {
 143                 SSL_CTX_set_session_id_context(ctx, (void *)&s_server_session_id_context, sizeof(s_server_session_id_context));
 144         }
 145 #endif
 146
 147         inited = 1;
 148         return 0;
 149
 150 die:
 151         return -1;
 152 }
 153
 154 SSL *ssl_promotion(int is_server, SOCKET s, char *errbuf, size_t errbuflen)
 155 {
 156         if (ssl_init_once(is_server, 1, errbuf, errbuflen) < 0) {
 157                 return NULL;
 158         }
 159
 160         SSL *ssl = SSL_new(ctx); // TODO: also a DTLS context
 161         SSL_set_fd(ssl, (int)s);
 162
 163         if (is_server) {
 164                 if (SSL_accept(ssl) <= 0) {
 165                         snprintf(errbuf, errbuflen, "SSL_accept(): %s",
 166                                         ERR_error_string(ERR_get_error(), NULL));
 167                         return NULL;
 168                 }
 169         } else {
 170                 if (SSL_connect(ssl) <= 0) {
 171                         snprintf(errbuf, errbuflen, "SSL_connect(): %s",
 172                                         ERR_error_string(ERR_get_error(), NULL));
 173                         return NULL;
 174                 }
 175         }
 176
 177         return ssl;
 178 }
 179
 180 // Finish using an SSL handle; shut down the connection and free the
 181 // handle.
 182 void ssl_finish(SSL *ssl)
 183 {
 184         //
 185         // We won't be using this again, so we can just send the
 186         // shutdown alert and free up the handle, and have our
 187         // caller close the socket.
 188         //
 189         // XXX - presumably, if the connection is shut down on
 190         // our side, either our peer won't have a problem sending
 191         // their shutdown alert or will not treat such a problem
 192         // as an error.  If this causes errors to be reported,
 193         // fix that as appropriate.
 194         //
 195         SSL_shutdown(ssl);
 196         SSL_free(ssl);
 197 }
 198
 199 // Same return value as sock_send:
 200 // 0 on OK, -1 on error but closed connection (-2).
 201 int ssl_send(SSL *ssl, char const *buffer, int size, char *errbuf, size_t errbuflen)
 202 {
 203         int status = SSL_write(ssl, buffer, size);
 204         if (status > 0)
 205         {
 206                 // "SSL_write() will only return with success, when the complete contents (...) has been written."
 207                 return 0;
 208         }
 209         else
 210         {
 211                 int ssl_err = SSL_get_error(ssl, status); // TODO: does it pop the error?
 212                 if (ssl_err == SSL_ERROR_ZERO_RETURN)
 213                 {
 214                         return -2;
 215                 }
 216                 else if (ssl_err == SSL_ERROR_SYSCALL)
 217                 {
 218 #ifndef _WIN32
 219                         if (errno == ECONNRESET || errno == EPIPE) return -2;
 220 #endif
 221                 }
 222                 snprintf(errbuf, errbuflen, "SSL_write(): %s",
 223                     ERR_error_string(ERR_get_error(), NULL));
 224                 return -1;
 225         }
 226 }
 227
 228 // Returns the number of bytes read, or -1 on syserror, or -2 on SSL error.
 229 int ssl_recv(SSL *ssl, char *buffer, int size, char *errbuf, size_t errbuflen)
 230 {
 231         int status = SSL_read(ssl, buffer, size);
 232         if (status <= 0)
 233         {
 234                 int ssl_err = SSL_get_error(ssl, status);
 235                 if (ssl_err == SSL_ERROR_ZERO_RETURN)
 236                 {
 237                         return 0;
 238                 }
 239                 else if (ssl_err == SSL_ERROR_SYSCALL)
 240                 {
 241                         return -1;
 242                 }
 243                 else
 244                 {
 245                         // Should not happen
 246                         snprintf(errbuf, errbuflen, "SSL_read(): %s",
 247                             ERR_error_string(ERR_get_error(), NULL));
 248                         return -2;
 249                 }
 250         }
 251         else
 252         {
 253                 return status;
 254         }
 255 }
 256
 257 #endif // HAVE_OPENSSL