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         const SSL_METHOD *ssl_method;
  54
  55 #ifndef OPENSSL_NO_EGD
  56         if (!access("/var/run/egd-pool", F_OK)) {
  57                 RAND_egd("/var/run/egd-pool");
  58         }
  59 #endif
  60
  61         if (!RAND_status()) {
  62                 syslog(LOG_WARNING, "PRNG not adequately seeded, won't do SSL/TLS");
  63                 return;
  64         }
  65
  66         // Initialize SSL transport layer
  67         SSL_library_init();
  68         SSL_load_error_strings();
  69         ssl_method = SSLv23_server_method();
  70         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
  71                 syslog(LOG_WARNING, "SSL_CTX_new failed: %s", ERR_reason_error_string(ERR_get_error()));
  72                 return;
  73         }
  74
  75         syslog(LOG_INFO, "Requesting cipher list: %s", ssl_cipher_list);
  76         if (!(SSL_CTX_set_cipher_list(ssl_ctx, ssl_cipher_list))) {
  77                 syslog(LOG_WARNING, "SSL_CTX_set_cipher_list failed: %s", ERR_reason_error_string(ERR_get_error()));
  78                 return;
  79         }
  80
  81
  82         // Now try to bind to the key and certificate.
  83         bind_to_key_and_certificate();
  84 }
  85
  86
  87 // Check the modification time of the key and certificate -- reload if they changed
  88 void update_key_and_cert_if_needed(void) {
  89         static time_t cert_mtime = 0;
  90         struct stat keystat;
  91         struct stat certstat;
  92
  93         if (stat(key_file, &keystat) != 0) {
  94                 syslog(LOG_ERR, "%s: %s", key_file, strerror(errno));
  95                 return;
  96         }
  97         if (stat(cert_file, &certstat) != 0) {
  98                 syslog(LOG_ERR, "%s: %s", cert_file, strerror(errno));
  99                 return;
 100         }
 101
 102         if ((keystat.st_mtime > cert_mtime) || (certstat.st_mtime > cert_mtime)) {
 103                 bind_to_key_and_certificate();
 104                 cert_mtime = certstat.st_mtime;
 105         }
 106 }
 107
 108
 109 // starts SSL/TLS encryption for the current session.
 110 int starttls(int sock) {
 111         SSL *newssl;
 112         int retval, bits, alg_bits;
 113
 114         // Check the modification time of the key and certificate -- reload if they changed
 115         update_key_and_cert_if_needed();
 116
 117         // SSL is a thread-specific thing, I think.
 118         pthread_setspecific(ThreadSSL, NULL);
 119
 120         if (!ssl_ctx) {
 121                 return(1);
 122         }
 123         if (!(newssl = SSL_new(ssl_ctx))) {
 124                 syslog(LOG_WARNING, "SSL_new failed: %s", ERR_reason_error_string(ERR_get_error()));
 125                 return(2);
 126         }
 127         if (!(SSL_set_fd(newssl, sock))) {
 128                 syslog(LOG_WARNING, "SSL_set_fd failed: %s", ERR_reason_error_string(ERR_get_error()));
 129                 SSL_free(newssl);
 130                 return(3);
 131         }
 132         retval = SSL_accept(newssl);
 133         if (retval < 1) {
 134                 // Can't notify the client of an error here; they will
 135                 // discover the problem at the SSL layer and should
 136                 // revert to unencrypted communications.
 137                 long errval;
 138                 const char *ssl_error_reason = NULL;
 139
 140                 errval = SSL_get_error(newssl, retval);
 141                 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 142                 if (ssl_error_reason == NULL) {
 143                         syslog(LOG_WARNING, "first SSL_accept failed: errval=%ld, retval=%d %s", errval, retval, strerror(errval));
 144                 }
 145                 else {
 146                         syslog(LOG_WARNING, "first SSL_accept failed: %s", ssl_error_reason);
 147                 }
 148                 // sleeeeeeeeeep(1);
 149                 // retval = SSL_accept(newssl);
 150         }
 151         // if (retval < 1) {
 152                 // long errval;
 153                 // const char *ssl_error_reason = NULL;
 154 //
 155                 // errval = SSL_get_error(newssl, retval);
 156                 // ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 157                 // if (ssl_error_reason == NULL) {
 158                         // syslog(LOG_WARNING, "second SSL_accept failed: errval=%ld, retval=%d (%s)", errval, retval, strerror(errval));
 159                 // }
 160                 // else {
 161                         // syslog(LOG_WARNING, "second SSL_accept failed: %s", ssl_error_reason);
 162                 // }
 163                 // SSL_free(newssl);
 164                 // newssl = NULL;
 165                 // return(4);
 166         // }
 167         else {
 168                 syslog(LOG_INFO, "SSL_accept success");
 169         }
 170         /*r = */BIO_set_close(SSL_get_rbio(newssl), BIO_NOCLOSE);
 171         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(newssl), &alg_bits);
 172         syslog(LOG_INFO, "SSL/TLS using %s on %s (%d of %d bits)",
 173                 SSL_CIPHER_get_name(SSL_get_current_cipher(newssl)),
 174                 SSL_CIPHER_get_version(SSL_get_current_cipher(newssl)),
 175                 bits, alg_bits);
 176
 177         pthread_setspecific(ThreadSSL, newssl);
 178         syslog(LOG_INFO, "SSL started");
 179         return(0);
 180 }
 181
 182
 183 // shuts down the TLS connection
 184 //
 185 // WARNING:  This may make your session vulnerable to a known plaintext
 186 // attack in the current implmentation.
 187 void endtls(void) {
 188
 189         if (THREADSSL == NULL) {
 190                 return;
 191         }
 192
 193         syslog(LOG_INFO, "Ending SSL/TLS");
 194         SSL_shutdown(THREADSSL);
 195         SSL_get_SSL_CTX(THREADSSL);
 196         SSL_free(THREADSSL);
 197         pthread_setspecific(ThreadSSL, NULL);
 198 }
 199
 200
 201 // Send binary data to the client encrypted.
 202 int client_write_ssl(const StrBuf *Buf) {
 203         const char *buf;
 204         int retval;
 205         int nremain;
 206         long nbytes;
 207         char junk[1];
 208
 209         if (THREADSSL == NULL) return -1;
 210
 211         nbytes = nremain = StrLength(Buf);
 212         buf = ChrPtr(Buf);
 213
 214         while (nremain > 0) {
 215                 if (SSL_want_write(THREADSSL)) {
 216                         if ((SSL_read(THREADSSL, junk, 0)) < 1) {
 217                                 syslog(LOG_WARNING, "SSL_read in client_write: %s", ERR_reason_error_string(ERR_get_error()));
 218                         }
 219                 }
 220                 retval = SSL_write(THREADSSL, &buf[nbytes - nremain], nremain);
 221                 if (retval < 1) {
 222                         long errval;
 223
 224                         errval = SSL_get_error(THREADSSL, retval);
 225                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 226                                 sleeeeeeeeeep(1);
 227                                 continue;
 228                         }
 229                         syslog(LOG_WARNING, "SSL_write: %s", ERR_reason_error_string(ERR_get_error()));
 230                         if (retval == -1) {
 231                                 syslog(LOG_WARNING, "errno is %d\n", errno);
 232                         }
 233                         endtls();
 234                         return -1;
 235                 }
 236                 nremain -= retval;
 237         }
 238         return 0;
 239 }
 240
 241
 242 // read data from the encrypted layer.
 243 int client_read_sslbuffer(StrBuf *buf, int timeout) {
 244         char sbuf[16384];       // OpenSSL communicates in 16k blocks, so let's speak its native tongue.
 245         int rlen;
 246         char junk[1];
 247         SSL *pssl = THREADSSL;
 248
 249         if (pssl == NULL) return(-1);
 250
 251         while (1) {
 252                 if (SSL_want_read(pssl)) {
 253                         if ((SSL_write(pssl, junk, 0)) < 1) {
 254                                 syslog(LOG_WARNING, "SSL_write in client_read");
 255                         }
 256                 }
 257                 rlen = SSL_read(pssl, sbuf, sizeof(sbuf));
 258                 if (rlen < 1) {
 259                         long errval;
 260
 261                         errval = SSL_get_error(pssl, rlen);
 262                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 263                                 sleeeeeeeeeep(1);
 264                                 continue;
 265                         }
 266                         syslog(LOG_WARNING, "SSL_read in client_read: %s", ERR_reason_error_string(ERR_get_error()));
 267                         endtls();
 268                         return (-1);
 269                 }
 270                 StrBufAppendBufPlain(buf, sbuf, rlen, 0);
 271                 return rlen;
 272         }
 273         return (0);
 274 }
 275
 276 #endif                          /* HAVE_OPENSSL */