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 "sslutils.h"
  41
  42 static const char *ssl_keyfile = "";   //!< file containing the private key in PEM format
  43 static const char *ssl_certfile = "";  //!< file containing the server's certificate in PEM format
  44 static const char *ssl_rootfile = "";  //!< file containing the list of CAs trusted by the client
  45 // TODO: a way to set ssl_rootfile from the command line, or an envvar?
  46
  47 // TODO: lock?
  48 static SSL_CTX *ctx;
  49
  50 void ssl_set_certfile(const char *certfile)
  51 {
  52         ssl_certfile = certfile;
  53 }
  54
  55 void ssl_set_keyfile(const char *keyfile)
  56 {
  57         ssl_keyfile = keyfile;
  58 }
  59
  60 int ssl_init_once(int is_server, int enable_compression, char *errbuf, size_t errbuflen)
  61 {
  62         static int inited = 0;
  63         if (inited) return 0;
  64
  65         SSL_library_init();
  66         SSL_load_error_strings();
  67         OpenSSL_add_ssl_algorithms();
  68         if (enable_compression)
  69                 SSL_COMP_get_compression_methods();
  70
  71         SSL_METHOD const *meth =
  72             is_server ? SSLv23_server_method() : SSLv23_client_method();
  73         ctx = SSL_CTX_new(meth);
  74         if (! ctx)
  75         {
  76                 pcap_snprintf(errbuf, errbuflen, "Cannot get a new SSL context: %s", ERR_error_string(ERR_get_error(), NULL));
  77                 goto die;
  78         }
  79
  80         SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
  81
  82         if (is_server)
  83         {
  84                 char const *certfile = ssl_certfile[0] ? ssl_certfile : "cert.pem";
  85                 if (1 != SSL_CTX_use_certificate_file(ctx, certfile, SSL_FILETYPE_PEM))
  86                 {
  87                         pcap_snprintf(errbuf, errbuflen, "Cannot read certificate file %s: %s", certfile, ERR_error_string(ERR_get_error(), NULL));
  88                         goto die;
  89                 }
  90
  91                 char const *keyfile = ssl_keyfile[0] ? ssl_keyfile : "key.pem";
  92                 if (1 != SSL_CTX_use_PrivateKey_file(ctx, keyfile, SSL_FILETYPE_PEM))
  93                 {
  94                         pcap_snprintf(errbuf, errbuflen, "Cannot read private key file %s: %s", keyfile, ERR_error_string(ERR_get_error(), NULL));
  95                         goto die;
  96                 }
  97         }
  98         else
  99         {
 100                 if (ssl_rootfile[0])
 101                 {
 102                         if (! SSL_CTX_load_verify_locations(ctx, ssl_rootfile, 0))
 103                         {
 104                                 pcap_snprintf(errbuf, errbuflen, "Cannot read CA list from %s", ssl_rootfile);
 105                                 goto die;
 106                         }
 107                 }
 108                 else
 109                 {
 110                         SSL_CTX_set_verify(ctx, SSL_VERIFY_NONE, NULL);
 111                 }
 112         }
 113
 114 #if 0
 115         if (! RAND_load_file(RANDOM, 1024*1024))
 116         {
 117                 pcap_snprintf(errbuf, errbuflen, "Cannot init random");
 118                 goto die;
 119         }
 120
 121         if (is_server)
 122         {
 123                 SSL_CTX_set_session_id_context(ctx, (void *)&s_server_session_id_context, sizeof(s_server_session_id_context));
 124         }
 125 #endif
 126
 127         inited = 1;
 128         return 0;
 129
 130 die:
 131         return -1;
 132 }
 133
 134 SSL *ssl_promotion_rw(int is_server, SOCKET in, SOCKET out, char *errbuf, size_t errbuflen)
 135 {
 136         if (ssl_init_once(is_server, 1, errbuf, errbuflen) < 0) {
 137                 return NULL;
 138         }
 139
 140         SSL *ssl = SSL_new(ctx); // TODO: also a DTLS context
 141         SSL_set_rfd(ssl, in);
 142         SSL_set_wfd(ssl, out);
 143
 144         if (is_server) {
 145                 if (SSL_accept(ssl) <= 0) {
 146                         pcap_snprintf(errbuf, errbuflen, "SSL_accept(): %s",
 147                                         ERR_error_string(ERR_get_error(), NULL));
 148                         return NULL;
 149                 }
 150         } else {
 151                 if (SSL_connect(ssl) <= 0) {
 152                         pcap_snprintf(errbuf, errbuflen, "SSL_connect(): %s",
 153                                         ERR_error_string(ERR_get_error(), NULL));
 154                         return NULL;
 155                 }
 156         }
 157
 158         return ssl;
 159 }
 160
 161 SSL *ssl_promotion(int is_server, SOCKET s, char *errbuf, size_t errbuflen)
 162 {
 163         return ssl_promotion_rw(is_server, s, s, errbuf, errbuflen);
 164 }
 165
 166 // Same return value as sock_send:
 167 // 0 on OK, -1 on error but closed connection (-2).
 168 int ssl_send(SSL *ssl, char const *buffer, int size, char *errbuf, size_t errbuflen)
 169 {
 170         int status = SSL_write(ssl, buffer, size);
 171         if (status > 0)
 172         {
 173                 // "SSL_write() will only return with success, when the complete contents (...) has been written."
 174                 return 0;
 175         }
 176         else
 177         {
 178                 int ssl_err = SSL_get_error(ssl, status); // TODO: does it pop the error?
 179                 if (ssl_err == SSL_ERROR_ZERO_RETURN)
 180                 {
 181                         return -2;
 182                 }
 183                 else if (ssl_err == SSL_ERROR_SYSCALL)
 184                 {
 185 #ifndef _WIN32
 186                         if (errno == ECONNRESET || errno == EPIPE) return -2;
 187 #endif
 188                 }
 189                 pcap_snprintf(errbuf, errbuflen, "SSL_write(): %s",
 190                     ERR_error_string(ERR_get_error(), NULL));
 191                 return -1;
 192         }
 193 }
 194
 195 // Returns the number of bytes read, or -1 on syserror, or -2 on SSL error.
 196 int ssl_recv(SSL *ssl, char *buffer, int size, char *errbuf, size_t errbuflen)
 197 {
 198         int status = SSL_read(ssl, buffer, size);
 199         if (status <= 0)
 200         {
 201                 int ssl_err = SSL_get_error(ssl, status);
 202                 if (ssl_err == SSL_ERROR_ZERO_RETURN)
 203                 {
 204                         return 0;
 205                 }
 206                 else if (ssl_err == SSL_ERROR_SYSCALL)
 207                 {
 208                         return -1;
 209                 }
 210                 else
 211                 {
 212                         // Should not happen
 213                         pcap_snprintf(errbuf, errbuflen, "SSL_read(): %s",
 214                             ERR_error_string(ERR_get_error(), NULL));
 215                         return -2;
 216                 }
 217         }
 218         else
 219         {
 220                 return status;
 221         }
 222 }
 223
 224 #endif // HAVE_OPENSSL