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 #ifndef OPENSSL_NO_EGD
  55         if (!access("/var/run/egd-pool", F_OK)) {
  56                 RAND_egd("/var/run/egd-pool");
  57         }
  58 #endif
  59
  60         if (!RAND_status()) {
  61                 syslog(LOG_WARNING, "PRNG not adequately seeded, won't do SSL/TLS");
  62                 return;
  63         }
  64
  65         // Initialize SSL transport layer
  66         SSL_library_init();
  67         SSL_load_error_strings();
  68         if (!(ssl_ctx = SSL_CTX_new(SSLv23_server_method()))) {
  69                 syslog(LOG_WARNING, "SSL_CTX_new failed: %s", ERR_reason_error_string(ERR_get_error()));
  70                 return;
  71         }
  72
  73         syslog(LOG_INFO, "Requesting cipher list: %s", ssl_cipher_list);
  74         if (!(SSL_CTX_set_cipher_list(ssl_ctx, ssl_cipher_list))) {
  75                 syslog(LOG_WARNING, "SSL_CTX_set_cipher_list failed: %s", ERR_reason_error_string(ERR_get_error()));
  76                 return;
  77         }
  78
  79
  80         // Now try to bind to the key and certificate.
  81         bind_to_key_and_certificate();
  82 }
  83
  84
  85 // Check the modification time of the key and certificate -- reload if either one changed
  86 void update_key_and_cert_if_needed(void) {
  87         static time_t previous_mtime = 0;
  88         struct stat keystat;
  89         struct stat certstat;
  90
  91         if (stat(key_file, &keystat) != 0) {
  92                 syslog(LOG_ERR, "%s: %s", key_file, strerror(errno));
  93                 return;
  94         }
  95         if (stat(cert_file, &certstat) != 0) {
  96                 syslog(LOG_ERR, "%s: %s", cert_file, strerror(errno));
  97                 return;
  98         }
  99
 100         if ((keystat.st_mtime + certstat.st_mtime) != previous_mtime) {
 101                 bind_to_key_and_certificate();
 102                 previous_mtime = keystat.st_mtime + certstat.st_mtime;
 103         }
 104 }
 105
 106
 107 // starts SSL/TLS encryption for the current session.
 108 int starttls(int sock) {
 109         SSL *newssl;
 110         int retval, bits, alg_bits;
 111
 112         // Check the modification time of the key and certificate -- reload if they changed
 113         update_key_and_cert_if_needed();
 114
 115         // SSL is a thread-specific thing, I think.
 116         pthread_setspecific(ThreadSSL, NULL);
 117
 118         if (!ssl_ctx) {
 119                 return(1);
 120         }
 121         if (!(newssl = SSL_new(ssl_ctx))) {
 122                 syslog(LOG_WARNING, "SSL_new failed: %s", ERR_reason_error_string(ERR_get_error()));
 123                 return(2);
 124         }
 125         if (!(SSL_set_fd(newssl, sock))) {
 126                 syslog(LOG_WARNING, "SSL_set_fd failed: %s", ERR_reason_error_string(ERR_get_error()));
 127                 SSL_free(newssl);
 128                 return(3);
 129         }
 130         retval = SSL_accept(newssl);
 131         if (retval < 1) {
 132                 // Can't notify the client of an error here; they will
 133                 // discover the problem at the SSL layer and should
 134                 // revert to unencrypted communications.
 135                 long errval;
 136                 const char *ssl_error_reason = NULL;
 137
 138                 errval = SSL_get_error(newssl, retval);
 139                 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 140                 if (ssl_error_reason == NULL) {
 141                         syslog(LOG_WARNING, "first SSL_accept failed: errval=%ld, retval=%d %s", errval, retval, strerror(errval));
 142                 }
 143                 else {
 144                         syslog(LOG_WARNING, "first SSL_accept failed: %s", ssl_error_reason);
 145                 }
 146                 // sleeeeeeeeeep(1);
 147                 // retval = SSL_accept(newssl);
 148         }
 149         // if (retval < 1) {
 150                 // long errval;
 151                 // const char *ssl_error_reason = NULL;
 152 //
 153                 // errval = SSL_get_error(newssl, retval);
 154                 // ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 155                 // if (ssl_error_reason == NULL) {
 156                         // syslog(LOG_WARNING, "second SSL_accept failed: errval=%ld, retval=%d (%s)", errval, retval, strerror(errval));
 157                 // }
 158                 // else {
 159                         // syslog(LOG_WARNING, "second SSL_accept failed: %s", ssl_error_reason);
 160                 // }
 161                 // SSL_free(newssl);
 162                 // newssl = NULL;
 163                 // return(4);
 164         // }
 165         else {
 166                 syslog(LOG_INFO, "SSL_accept success");
 167         }
 168         /*r = */BIO_set_close(SSL_get_rbio(newssl), BIO_NOCLOSE);
 169         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(newssl), &alg_bits);
 170         syslog(LOG_INFO, "SSL/TLS using %s on %s (%d of %d bits)",
 171                 SSL_CIPHER_get_name(SSL_get_current_cipher(newssl)),
 172                 SSL_CIPHER_get_version(SSL_get_current_cipher(newssl)),
 173                 bits, alg_bits);
 174
 175         pthread_setspecific(ThreadSSL, newssl);
 176         syslog(LOG_INFO, "SSL started");
 177         return(0);
 178 }
 179
 180
 181 // shuts down the TLS connection
 182 //
 183 // WARNING:  This may make your session vulnerable to a known plaintext
 184 // attack in the current implmentation.
 185 void endtls(void) {
 186
 187         if (THREADSSL == NULL) {
 188                 return;
 189         }
 190
 191         syslog(LOG_INFO, "Ending SSL/TLS");
 192         SSL_shutdown(THREADSSL);
 193         SSL_get_SSL_CTX(THREADSSL);
 194         SSL_free(THREADSSL);
 195         pthread_setspecific(ThreadSSL, NULL);
 196 }
 197
 198
 199 // Send binary data to the client encrypted.
 200 int client_write_ssl(const StrBuf *Buf) {
 201         const char *buf;
 202         int retval;
 203         int nremain;
 204         long nbytes;
 205         char junk[1];
 206
 207         if (THREADSSL == NULL) return -1;
 208
 209         nbytes = nremain = StrLength(Buf);
 210         buf = ChrPtr(Buf);
 211
 212         while (nremain > 0) {
 213                 if (SSL_want_write(THREADSSL)) {
 214                         if ((SSL_read(THREADSSL, junk, 0)) < 1) {
 215                                 syslog(LOG_WARNING, "SSL_read in client_write: %s", ERR_reason_error_string(ERR_get_error()));
 216                         }
 217                 }
 218                 retval = SSL_write(THREADSSL, &buf[nbytes - nremain], nremain);
 219                 if (retval < 1) {
 220                         long errval;
 221
 222                         errval = SSL_get_error(THREADSSL, retval);
 223                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 224                                 sleeeeeeeeeep(1);
 225                                 continue;
 226                         }
 227                         syslog(LOG_WARNING, "SSL_write: %s", ERR_reason_error_string(ERR_get_error()));
 228                         if (retval == -1) {
 229                                 syslog(LOG_WARNING, "errno is %d\n", errno);
 230                         }
 231                         endtls();
 232                         return -1;
 233                 }
 234                 nremain -= retval;
 235         }
 236         return 0;
 237 }
 238
 239
 240 // read data from the encrypted layer.
 241 int client_read_sslbuffer(StrBuf *buf, int timeout) {
 242         char sbuf[16384];       // OpenSSL communicates in 16k blocks, so let's speak its native tongue.
 243         int rlen;
 244         char junk[1];
 245         SSL *pssl = THREADSSL;
 246
 247         if (pssl == NULL) return(-1);
 248
 249         while (1) {
 250                 if (SSL_want_read(pssl)) {
 251                         if ((SSL_write(pssl, junk, 0)) < 1) {
 252                                 syslog(LOG_WARNING, "SSL_write in client_read");
 253                         }
 254                 }
 255                 rlen = SSL_read(pssl, sbuf, sizeof(sbuf));
 256                 if (rlen < 1) {
 257                         long errval;
 258
 259                         errval = SSL_get_error(pssl, rlen);
 260                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 261                                 sleeeeeeeeeep(1);
 262                                 continue;
 263                         }
 264                         syslog(LOG_WARNING, "SSL_read in client_read: %s", ERR_reason_error_string(ERR_get_error()));
 265                         endtls();
 266                         return (-1);
 267                 }
 268                 StrBufAppendBufPlain(buf, sbuf, rlen, 0);
 269                 return rlen;
 270         }
 271         return (0);
 272 }
 273
 274 #endif                          /* HAVE_OPENSSL */