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         SSL_library_init();
  68         SSL_load_error_strings();
  69         OpenSSL_add_ssl_algorithms();
  70         if (enable_compression)
  71                 SSL_COMP_get_compression_methods();
  72
  73         SSL_METHOD const *meth =
  74             is_server ? SSLv23_server_method() : SSLv23_client_method();
  75         ctx = SSL_CTX_new(meth);
  76         if (! ctx)
  77         {
  78                 pcap_snprintf(errbuf, errbuflen, "Cannot get a new SSL context: %s", ERR_error_string(ERR_get_error(), NULL));
  79                 goto die;
  80         }
  81
  82         SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
  83
  84         if (is_server)
  85         {
  86                 char const *certfile = ssl_certfile[0] ? ssl_certfile : "cert.pem";
  87                 if (1 != SSL_CTX_use_certificate_file(ctx, certfile, SSL_FILETYPE_PEM))
  88                 {
  89                         pcap_snprintf(errbuf, errbuflen, "Cannot read certificate file %s: %s", certfile, ERR_error_string(ERR_get_error(), NULL));
  90                         goto die;
  91                 }
  92
  93                 char const *keyfile = ssl_keyfile[0] ? ssl_keyfile : "key.pem";
  94                 if (1 != SSL_CTX_use_PrivateKey_file(ctx, keyfile, SSL_FILETYPE_PEM))
  95                 {
  96                         pcap_snprintf(errbuf, errbuflen, "Cannot read private key file %s: %s", keyfile, ERR_error_string(ERR_get_error(), NULL));
  97                         goto die;
  98                 }
  99         }
 100         else
 101         {
 102                 if (ssl_rootfile[0])
 103                 {
 104                         if (! SSL_CTX_load_verify_locations(ctx, ssl_rootfile, 0))
 105                         {
 106                                 pcap_snprintf(errbuf, errbuflen, "Cannot read CA list from %s", ssl_rootfile);
 107                                 goto die;
 108                         }
 109                 }
 110                 else
 111                 {
 112                         SSL_CTX_set_verify(ctx, SSL_VERIFY_NONE, NULL);
 113                 }
 114         }
 115
 116 #if 0
 117         if (! RAND_load_file(RANDOM, 1024*1024))
 118         {
 119                 pcap_snprintf(errbuf, errbuflen, "Cannot init random");
 120                 goto die;
 121         }
 122
 123         if (is_server)
 124         {
 125                 SSL_CTX_set_session_id_context(ctx, (void *)&s_server_session_id_context, sizeof(s_server_session_id_context));
 126         }
 127 #endif
 128
 129         inited = 1;
 130         return 0;
 131
 132 die:
 133         return -1;
 134 }
 135
 136 SSL *ssl_promotion(int is_server, SOCKET s, char *errbuf, size_t errbuflen)
 137 {
 138         if (ssl_init_once(is_server, 1, errbuf, errbuflen) < 0) {
 139                 return NULL;
 140         }
 141
 142         SSL *ssl = SSL_new(ctx); // TODO: also a DTLS context
 143         SSL_set_fd(ssl, s);
 144
 145         if (is_server) {
 146                 if (SSL_accept(ssl) <= 0) {
 147                         pcap_snprintf(errbuf, errbuflen, "SSL_accept(): %s",
 148                                         ERR_error_string(ERR_get_error(), NULL));
 149                         return NULL;
 150                 }
 151         } else {
 152                 if (SSL_connect(ssl) <= 0) {
 153                         pcap_snprintf(errbuf, errbuflen, "SSL_connect(): %s",
 154                                         ERR_error_string(ERR_get_error(), NULL));
 155                         return NULL;
 156                 }
 157         }
 158
 159         return ssl;
 160 }
 161
 162 // Finish using an SSL handle; shut down the connection and free the
 163 // handle.
 164 void ssl_finish(SSL *ssl)
 165 {
 166         //
 167         // We won't be using this again, so we can just send the
 168         // shutdown alert and free up the handle, and have our
 169         // caller close the socket.
 170         //
 171         // XXX - presumably, if the connection is shut down on
 172         // our side, either our peer won't have a problem sending
 173         // their shutdown alert or will not treat such a problem
 174         // as an error.  If this causes errors to be reported,
 175         // fix that as appropriate.
 176         //
 177         SSL_shutdown(ssl);
 178         SSL_free(ssl);
 179 }
 180
 181 // Same return value as sock_send:
 182 // 0 on OK, -1 on error but closed connection (-2).
 183 int ssl_send(SSL *ssl, char const *buffer, int size, char *errbuf, size_t errbuflen)
 184 {
 185         int status = SSL_write(ssl, buffer, size);
 186         if (status > 0)
 187         {
 188                 // "SSL_write() will only return with success, when the complete contents (...) has been written."
 189                 return 0;
 190         }
 191         else
 192         {
 193                 int ssl_err = SSL_get_error(ssl, status); // TODO: does it pop the error?
 194                 if (ssl_err == SSL_ERROR_ZERO_RETURN)
 195                 {
 196                         return -2;
 197                 }
 198                 else if (ssl_err == SSL_ERROR_SYSCALL)
 199                 {
 200 #ifndef _WIN32
 201                         if (errno == ECONNRESET || errno == EPIPE) return -2;
 202 #endif
 203                 }
 204                 pcap_snprintf(errbuf, errbuflen, "SSL_write(): %s",
 205                     ERR_error_string(ERR_get_error(), NULL));
 206                 return -1;
 207         }
 208 }
 209
 210 // Returns the number of bytes read, or -1 on syserror, or -2 on SSL error.
 211 int ssl_recv(SSL *ssl, char *buffer, int size, char *errbuf, size_t errbuflen)
 212 {
 213         int status = SSL_read(ssl, buffer, size);
 214         if (status <= 0)
 215         {
 216                 int ssl_err = SSL_get_error(ssl, status);
 217                 if (ssl_err == SSL_ERROR_ZERO_RETURN)
 218                 {
 219                         return 0;
 220                 }
 221                 else if (ssl_err == SSL_ERROR_SYSCALL)
 222                 {
 223                         return -1;
 224                 }
 225                 else
 226                 {
 227                         // Should not happen
 228                         pcap_snprintf(errbuf, errbuflen, "SSL_read(): %s",
 229                             ERR_error_string(ERR_get_error(), NULL));
 230                         return -2;
 231                 }
 232         }
 233         else
 234         {
 235                 return status;
 236         }
 237 }
 238
 239 #endif // HAVE_OPENSSL