webcit/crypto.c

   1 // Copyright (c) 1996-2021 by the citadel.org team
   2 //
   3 // This program is open source software.  You can redistribute it and/or
   4 // modify it under the terms of the GNU General Public License, version 3.
   5 //
   6 // This program is distributed in the hope that it will be useful,
   7 // but WITHOUT ANY WARRANTY; without even the implied warranty of
   8 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   9 // GNU General Public License for more details.
  10
  11 #include "sysdep.h"
  12 #ifdef HAVE_OPENSSL
  13
  14 #include "webcit.h"
  15 #include "webserver.h"
  16
  17
  18 SSL_CTX *ssl_ctx;               // Global SSL context
  19 char key_file[PATH_MAX] = "";
  20 char cert_file[PATH_MAX] = "";
  21 char *ssl_cipher_list = DEFAULT_SSL_CIPHER_LIST;
  22
  23 pthread_key_t ThreadSSL;        // Per-thread SSL context
  24
  25 void shutdown_ssl(void) {
  26         ERR_free_strings();
  27 }
  28
  29
  30 // Set the private key and certificate chain for the global SSL Context.
  31 // This is called during initialization, and can be called again later if the certificate changes.
  32 void bind_to_key_and_certificate(void) {
  33         if (IsEmptyStr(key_file)) {
  34                 snprintf(key_file, sizeof key_file, "%s/keys/citadel.key", ctdl_dir);
  35         }
  36         if (IsEmptyStr(cert_file)) {
  37                 snprintf(cert_file, sizeof key_file, "%s/keys/citadel.cer", ctdl_dir);
  38         }
  39
  40         syslog(LOG_DEBUG, "crypto: [re]installing key \"%s\" and certificate \"%s\"", key_file, cert_file);
  41
  42         SSL_CTX_use_certificate_chain_file(ssl_ctx, cert_file);
  43         SSL_CTX_use_PrivateKey_file(ssl_ctx, key_file, SSL_FILETYPE_PEM);
  44
  45         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
  46                 syslog(LOG_WARNING, "crypto: cannot install certificate: %s", ERR_reason_error_string(ERR_get_error()));
  47         }
  48 }
  49
  50
  51 // initialize ssl engine, load certs and initialize openssl internals
  52 void init_ssl(void) {
  53
  54         // Initialize SSL transport layer
  55         SSL_library_init();
  56         SSL_load_error_strings();
  57         if (!(ssl_ctx = SSL_CTX_new(SSLv23_server_method()))) {
  58                 syslog(LOG_WARNING, "SSL_CTX_new failed: %s", ERR_reason_error_string(ERR_get_error()));
  59                 return;
  60         }
  61
  62         syslog(LOG_INFO, "Requesting cipher list: %s", ssl_cipher_list);
  63         if (!(SSL_CTX_set_cipher_list(ssl_ctx, ssl_cipher_list))) {
  64                 syslog(LOG_WARNING, "SSL_CTX_set_cipher_list failed: %s", ERR_reason_error_string(ERR_get_error()));
  65                 return;
  66         }
  67
  68
  69         // Now try to bind to the key and certificate.
  70         bind_to_key_and_certificate();
  71 }
  72
  73
  74 // Check the modification time of the key and certificate -- reload if either one changed
  75 void update_key_and_cert_if_needed(void) {
  76         static time_t previous_mtime = 0;
  77         struct stat keystat;
  78         struct stat certstat;
  79
  80         if (stat(key_file, &keystat) != 0) {
  81                 syslog(LOG_ERR, "%s: %s", key_file, strerror(errno));
  82                 return;
  83         }
  84         if (stat(cert_file, &certstat) != 0) {
  85                 syslog(LOG_ERR, "%s: %s", cert_file, strerror(errno));
  86                 return;
  87         }
  88
  89         if ((keystat.st_mtime + certstat.st_mtime) != previous_mtime) {
  90                 bind_to_key_and_certificate();
  91                 previous_mtime = keystat.st_mtime + certstat.st_mtime;
  92         }
  93 }
  94
  95
  96 // starts SSL/TLS encryption for the current session.
  97 int starttls(int sock) {
  98         SSL *newssl;
  99         int retval, bits, alg_bits;
 100
 101         // Check the modification time of the key and certificate -- reload if they changed
 102         update_key_and_cert_if_needed();
 103
 104         // SSL is a thread-specific thing, I think.
 105         pthread_setspecific(ThreadSSL, NULL);
 106
 107         if (!ssl_ctx) {
 108                 return(1);
 109         }
 110         if (!(newssl = SSL_new(ssl_ctx))) {
 111                 syslog(LOG_WARNING, "SSL_new failed: %s", ERR_reason_error_string(ERR_get_error()));
 112                 return(2);
 113         }
 114         if (!(SSL_set_fd(newssl, sock))) {
 115                 syslog(LOG_WARNING, "SSL_set_fd failed: %s", ERR_reason_error_string(ERR_get_error()));
 116                 SSL_free(newssl);
 117                 return(3);
 118         }
 119         retval = SSL_accept(newssl);
 120         if (retval < 1) {
 121                 // Can't notify the client of an error here; they will
 122                 // discover the problem at the SSL layer and should
 123                 // revert to unencrypted communications.
 124                 long errval;
 125                 const char *ssl_error_reason = NULL;
 126
 127                 errval = SSL_get_error(newssl, retval);
 128                 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 129                 if (ssl_error_reason == NULL) {
 130                         syslog(LOG_WARNING, "first SSL_accept failed: errval=%ld, retval=%d %s", errval, retval, strerror(errval));
 131                 }
 132                 else {
 133                         syslog(LOG_WARNING, "first SSL_accept failed: %s", ssl_error_reason);
 134                 }
 135                 // sleeeeeeeeeep(1);
 136                 // retval = SSL_accept(newssl);
 137         }
 138         // if (retval < 1) {
 139                 // long errval;
 140                 // const char *ssl_error_reason = NULL;
 141 //
 142                 // errval = SSL_get_error(newssl, retval);
 143                 // ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 144                 // if (ssl_error_reason == NULL) {
 145                         // syslog(LOG_WARNING, "second SSL_accept failed: errval=%ld, retval=%d (%s)", errval, retval, strerror(errval));
 146                 // }
 147                 // else {
 148                         // syslog(LOG_WARNING, "second SSL_accept failed: %s", ssl_error_reason);
 149                 // }
 150                 // SSL_free(newssl);
 151                 // newssl = NULL;
 152                 // return(4);
 153         // }
 154         else {
 155                 syslog(LOG_INFO, "SSL_accept success");
 156         }
 157         /*r = */BIO_set_close(SSL_get_rbio(newssl), BIO_NOCLOSE);
 158         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(newssl), &alg_bits);
 159         syslog(LOG_INFO, "SSL/TLS using %s on %s (%d of %d bits)",
 160                 SSL_CIPHER_get_name(SSL_get_current_cipher(newssl)),
 161                 SSL_CIPHER_get_version(SSL_get_current_cipher(newssl)),
 162                 bits, alg_bits);
 163
 164         pthread_setspecific(ThreadSSL, newssl);
 165         syslog(LOG_INFO, "SSL started");
 166         return(0);
 167 }
 168
 169
 170 // shuts down the TLS connection
 171 //
 172 // WARNING:  This may make your session vulnerable to a known plaintext
 173 // attack in the current implmentation.
 174 void endtls(void) {
 175
 176         if (THREADSSL == NULL) {
 177                 return;
 178         }
 179
 180         syslog(LOG_INFO, "Ending SSL/TLS");
 181         SSL_shutdown(THREADSSL);
 182         SSL_get_SSL_CTX(THREADSSL);
 183         SSL_free(THREADSSL);
 184         pthread_setspecific(ThreadSSL, NULL);
 185 }
 186
 187
 188 // Send binary data to the client encrypted.
 189 int client_write_ssl(const StrBuf *Buf) {
 190         const char *buf;
 191         int retval;
 192         int nremain;
 193         long nbytes;
 194         char junk[1];
 195
 196         if (THREADSSL == NULL) return -1;
 197
 198         nbytes = nremain = StrLength(Buf);
 199         buf = ChrPtr(Buf);
 200
 201         while (nremain > 0) {
 202                 if (SSL_want_write(THREADSSL)) {
 203                         if ((SSL_read(THREADSSL, junk, 0)) < 1) {
 204                                 syslog(LOG_WARNING, "SSL_read in client_write: %s", ERR_reason_error_string(ERR_get_error()));
 205                         }
 206                 }
 207                 retval = SSL_write(THREADSSL, &buf[nbytes - nremain], nremain);
 208                 if (retval < 1) {
 209                         long errval;
 210
 211                         errval = SSL_get_error(THREADSSL, retval);
 212                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 213                                 sleeeeeeeeeep(1);
 214                                 continue;
 215                         }
 216                         syslog(LOG_WARNING, "SSL_write: %s", ERR_reason_error_string(ERR_get_error()));
 217                         if (retval == -1) {
 218                                 syslog(LOG_WARNING, "errno is %d\n", errno);
 219                         }
 220                         endtls();
 221                         return -1;
 222                 }
 223                 nremain -= retval;
 224         }
 225         return 0;
 226 }
 227
 228
 229 // read data from the encrypted layer.
 230 int client_read_sslbuffer(StrBuf *buf, int timeout) {
 231         char sbuf[16384];       // OpenSSL communicates in 16k blocks, so let's speak its native tongue.
 232         int rlen;
 233         char junk[1];
 234         SSL *pssl = THREADSSL;
 235
 236         if (pssl == NULL) return(-1);
 237
 238         while (1) {
 239                 if (SSL_want_read(pssl)) {
 240                         if ((SSL_write(pssl, junk, 0)) < 1) {
 241                                 syslog(LOG_WARNING, "SSL_write in client_read");
 242                         }
 243                 }
 244                 rlen = SSL_read(pssl, sbuf, sizeof(sbuf));
 245                 if (rlen < 1) {
 246                         long errval;
 247
 248                         errval = SSL_get_error(pssl, rlen);
 249                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 250                                 sleeeeeeeeeep(1);
 251                                 continue;
 252                         }
 253                         syslog(LOG_WARNING, "SSL_read in client_read: %s", ERR_reason_error_string(ERR_get_error()));
 254                         endtls();
 255                         return (-1);
 256                 }
 257                 StrBufAppendBufPlain(buf, sbuf, rlen, 0);
 258                 return rlen;
 259         }
 260         return (0);
 261 }
 262
 263 #endif                          /* HAVE_OPENSSL */