/********************************************************************* * * File : $Source: /cvsroot/ijbswa/current/ssl_common.c,v $ * * Purpose : File with TLS/SSL extension. Contains methods for * creating, using and closing TLS/SSL connections that do * not depend on particular TLS/SSL library. * * Copyright : Written by and Copyright (c) 2017 Vaclav Svec. FIT CVUT. * Copyright (C) 2018-2021 by Fabian Keil * * This program is free software; you can redistribute it * and/or modify it under the terms of the GNU General * Public License as published by the Free Software * Foundation; either version 2 of the License, or (at * your option) any later version. * * This program is distributed in the hope that it will * be useful, but WITHOUT ANY WARRANTY; without even the * implied warranty of MERCHANTABILITY or FITNESS FOR A * PARTICULAR PURPOSE. See the GNU General Public * License for more details. * * The GNU General Public License should be included with * this file. If not, you can view it at * http://www.gnu.org/copyleft/gpl.html * or write to the Free Software Foundation, Inc., 59 * Temple Place - Suite 330, Boston, MA 02111-1307, USA. * *********************************************************************/ #include #include #include #include "config.h" #include "project.h" #include "miscutil.h" #include "errlog.h" #include "ssl.h" #include "ssl_common.h" /* * Macros for ssl_common.c */ #define CERT_SERIAL_NUM_LENGTH 4 /* Bytes of hash to be used for creating serial number of certificate. Min=2 and max=16 */ /********************************************************************* * * Function : client_use_ssl * * Description : Tests if client in current client state structure * should use SSL connection or standard connection. * * Parameters : * 1 : csp = Current client state (buffers, headers, etc...) * * Returns : If client should use TLS/SSL connection, 1 is returned. * Otherwise 0 is returned. * *********************************************************************/ extern int client_use_ssl(const struct client_state *csp) { return csp->http->client_ssl; } /********************************************************************* * * Function : server_use_ssl * * Description : Tests if server in current client state structure * should use SSL connection or standard connection. * * Parameters : * 1 : csp = Current client state (buffers, headers, etc...) * * Returns : If server should use TLS/SSL connection, 1 is returned. * Otherwise 0 is returned. * *********************************************************************/ extern int server_use_ssl(const struct client_state *csp) { return csp->http->server_ssl; } /********************************************************************* * * Function : ssl_send_data_delayed * * Description : Sends the contents of buf (for n bytes) to given SSL * connection, optionally delaying the operation. * * Parameters : * 1 : ssl_attr = SSL context to send data to * 2 : buf = Pointer to data to be sent * 3 : len = Length of data to be sent to the SSL context * 4 : delay = Delay in milliseconds. * * Returns : 0 on success (entire buffer sent). * nonzero on error. * *********************************************************************/ extern int ssl_send_data_delayed(struct ssl_attr* ssl_attr, const unsigned char *buf, size_t len, unsigned int delay) { size_t i = 0; if (delay == 0) { if (ssl_send_data(ssl_attr, buf, len) < 0) { return -1; } else { return 0; } } while (i < len) { size_t write_length; enum { MAX_WRITE_LENGTH = 10 }; if ((i + MAX_WRITE_LENGTH) > len) { write_length = len - i; } else { write_length = MAX_WRITE_LENGTH; } privoxy_millisleep(delay); if (ssl_send_data(ssl_attr, buf + i, write_length) < 0) { return -1; } i += write_length; } return 0; } /********************************************************************* * * Function : ssl_flush_socket * * Description : Send any pending "buffered" content with given * SSL connection. Alternative to function flush_socket. * * Parameters : * 1 : ssl_attr = SSL context to send buffer to * 2 : iob = The I/O buffer to flush, usually csp->iob. * * Returns : On success, the number of bytes send are returned (zero * indicates nothing was sent). On error, -1 is returned. * *********************************************************************/ extern long ssl_flush_socket(struct ssl_attr *ssl_attr, struct iob *iob) { /* Computing length of buffer part to send */ long len = iob->eod - iob->cur; if (len <= 0) { return(0); } /* Sending data to given SSl context */ if (ssl_send_data(ssl_attr, (const unsigned char *)iob->cur, (size_t)len) < 0) { return -1; } iob->eod = iob->cur = iob->buf; return(len); } /********************************************************************* * * Function : close_client_and_server_ssl_connections * * Description : Checks if client or server should use secured * connection over SSL and if so, closes all of them. * * Parameters : * 1 : csp = Current client state (buffers, headers, etc...) * * Returns : N/A * *********************************************************************/ extern void close_client_and_server_ssl_connections(struct client_state *csp) { if (client_use_ssl(csp) == 1) { close_client_ssl_connection(csp); } if (server_use_ssl(csp) == 1) { close_server_ssl_connection(csp); } } /********************************************************************* * * Function : tunnel_established_successfully * * Description : Check if parent proxy server response contains * information about successfully created connection with * destination server. (HTTP/... 2xx ...) * * Parameters : * 1 : server_response = Buffer with parent proxy server response * 2 : response_len = Length of server_response * * Returns : 1 => Connection created successfully * 0 => Connection wasn't created successfully * *********************************************************************/ extern int tunnel_established_successfully(const char *server_response, unsigned int response_len) { unsigned int pos = 0; if (server_response == NULL) { return 0; } /* Tests if "HTTP/" string is at the begin of received response */ if (strncmp(server_response, "HTTP/", 5) != 0) { return 0; } for (pos = 0; pos < response_len; pos++) { if (server_response[pos] == ' ') { break; } } /* * response_len -3 because of buffer end, response structure and 200 code. * There must be at least 3 chars after space. * End of buffer: ... 2xx'\0' * pos = | */ if (pos >= (response_len - 3)) { return 0; } /* Test HTTP status code */ if (server_response[pos + 1] != '2') { return 0; } return 1; } /********************************************************************* * * Function : free_certificate_chain * * Description : Frees certificates linked list. This linked list is * used to save information about certificates in * trusted chain. * * Parameters : * 1 : csp = Current client state (buffers, headers, etc...) * * Returns : N/A * *********************************************************************/ extern void free_certificate_chain(struct client_state *csp) { struct certs_chain *cert = csp->server_certs_chain.next; /* Cleaning buffers */ memset(csp->server_certs_chain.info_buf, 0, sizeof(csp->server_certs_chain.info_buf)); memset(csp->server_certs_chain.file_buf, 0, sizeof(csp->server_certs_chain.file_buf)); csp->server_certs_chain.next = NULL; /* Freeing memory in whole linked list */ while (cert != NULL) { struct certs_chain *cert_for_free = cert; cert = cert->next; freez(cert_for_free); } } /********************************************************************* * * Function : ssl_send_certificate_error * * Description : Sends info about invalid server certificate to client. * Sent message is including all trusted chain certificates, * that can be downloaded in web browser. * * Parameters : * 1 : csp = Current client state (buffers, headers, etc...) * * Returns : N/A * *********************************************************************/ extern void ssl_send_certificate_error(struct client_state *csp) { struct ssl_attr *ssl_attr = &csp->ssl_client_attr; size_t message_len = 0; int ret = 0; struct certs_chain *cert = NULL; const size_t head_length = 63; /* Header of message with certificate information */ const char message_begin[] = "HTTP/1.1 403 Certificate validation failed\r\n" "Content-Type: text/html\r\n" "Connection: close\r\n\r\n" "\n" "Server certificate verification failed\n" "

Server certificate verification failed

\n" "

Privoxy was unable " "to securely connect to the destination server.

" "

Reason: "; const char message_end[] = "\n"; char reason[INVALID_CERT_INFO_BUF_SIZE]; memset(reason, 0, sizeof(reason)); /* Get verification message from verification return code */ ssl_crt_verify_info(reason, sizeof(reason), csp); /* * Computing total length of message with all certificates inside */ message_len = strlen(message_begin) + strlen(message_end) + strlen(reason) + strlen("

") + 1; cert = &(csp->server_certs_chain); while (cert->next != NULL) { size_t base64_len = 4 * ((strlen(cert->file_buf) + 2) / 3) + 1; message_len += strlen(cert->info_buf) + strlen("
\n")
                     +  base64_len + strlen("Download certificate");
      cert = cert->next;
   }

   /*
    * Joining all blocks in one long message
    */
   char message[message_len];
   memset(message, 0, message_len);

   strlcpy(message, message_begin, message_len);
   strlcat(message, reason       , message_len);
   strlcat(message, "
"       , message_len);

   cert = &(csp->server_certs_chain);
   while (cert->next != NULL)
   {
      size_t olen = 0;
      size_t base64_len = 4 * ((strlen(cert->file_buf) + 2) / 3) + 1; /* +1 for terminating null*/
      char base64_buf[base64_len];
      memset(base64_buf, 0, base64_len);

      /* Encoding certificate into base64 code */
      ret = ssl_base64_encode((unsigned char*)base64_buf,
               base64_len, &olen, (const unsigned char*)cert->file_buf,
               strlen(cert->file_buf));
      if (ret != 0)
      {
         log_error(LOG_LEVEL_ERROR,
            "Encoding to base64 failed, buffer is to small");
      }

      strlcat(message, "
",        message_len);
      strlcat(message, cert->info_buf, message_len);
      strlcat(message, "
\n",     message_len);

      if (ret == 0)
      {
         strlcat(message, "Download certificate", message_len);
      }

      cert = cert->next;
   }
   strlcat(message, message_end, message_len);

   /*
    * Sending final message to client
    */
   (void)ssl_send_data(ssl_attr, (const unsigned char *)message, strlen(message));

   free_certificate_chain(csp);

   log_error(LOG_LEVEL_CRUNCH, "Certificate error: %s: https://%s%s",
      reason, csp->http->hostport, csp->http->path);
   log_error(LOG_LEVEL_CLF, "%s - - [%T] \"%s https://%s%s %s\" 403 %lu",
      csp->ip_addr_str, csp->http->gpc, csp->http->hostport, csp->http->path,
      csp->http->version, message_len-head_length);

#ifdef FEATURE_CONNECTION_KEEP_ALIVE
   csp->flags &= ~CSP_FLAG_CLIENT_CONNECTION_KEEP_ALIVE;
   csp->flags |= CSP_FLAG_SERVER_SOCKET_TAINTED;
#endif
}


/*********************************************************************
 *
 * Function    :  file_exists
 *
 * Description :  Tests if file exists and is readable.
 *
 * Parameters  :
 *          1  :  path = Path to tested file.
 *
 * Returns     :  1 => File exists and is readable.
 *                0 => File doesn't exist or is not readable.
 *
 *********************************************************************/
extern int file_exists(const char *path)
{
   FILE *f;
   if ((f = fopen(path, "r")) != NULL)
   {
      fclose(f);
      return 1;
   }

   return 0;
}


/*********************************************************************
 *
 * Function    :  make_certs_path
 *
 * Description : Creates path to file from three pieces. This function
 *               takes parameters and puts them in one new mallocated
 *               char * in correct order. Returned variable must be freed
 *               by caller. This function is mainly used for creating
 *               paths of certificates and keys files.
 *
 * Parameters  :
 *          1  :  conf_dir  = Name/path of directory where is the file.
 *                            '.' can be used for current directory.
 *          2  :  file_name = Name of file in conf_dir without suffix.
 *          3  :  suffix    = Suffix of given file_name.
 *
 * Returns     :  path => Path was built up successfully
 *                NULL => Path can't be built up
 *
 *********************************************************************/
extern char *make_certs_path(const char *conf_dir, const char *file_name,
   const char *suffix)
{
   /* Test if all given parameters are valid */
   if (conf_dir == NULL || *conf_dir == '\0' || file_name == NULL ||
      *file_name == '\0' || suffix == NULL || *suffix == '\0')
   {
      log_error(LOG_LEVEL_ERROR,
         "make_certs_path failed: bad input parameters");
      return NULL;
   }

   char *path = NULL;
   size_t path_size = strlen(conf_dir)
      + strlen(file_name) + strlen(suffix) + 2;

   /* Setting delimiter and editing path length */
#if defined(_WIN32)
   char delim[] = "\\";
   path_size += 1;
#else /* ifndef _WIN32 */
   char delim[] = "/";
#endif /* ifndef _WIN32 */

   /*
    * Building up path from many parts
    */
#if defined(unix)
   if (*conf_dir != '/' && basedir && *basedir)
   {
      /*
       * Replacing conf_dir with basedir. This new variable contains
       * absolute path to cwd.
       */
      path_size += strlen(basedir) + 2;
      path = zalloc_or_die(path_size);

      strlcpy(path, basedir,   path_size);
      strlcat(path, delim,     path_size);
      strlcat(path, conf_dir,  path_size);
      strlcat(path, delim,     path_size);
      strlcat(path, file_name, path_size);
      strlcat(path, suffix,    path_size);
   }
   else
#endif /* defined unix */
   {
      path = zalloc_or_die(path_size);

      strlcpy(path, conf_dir,  path_size);
      strlcat(path, delim,     path_size);
      strlcat(path, file_name, path_size);
      strlcat(path, suffix,    path_size);
   }

   return path;
}


/*********************************************************************
 *
 * Function    :  get_certificate_serial
 *
 * Description :  Computes serial number for new certificate from host
 *                name hash. This hash must be already saved in csp
 *                structure.
 *
 * Parameters  :
 *          1  :  csp = Current client state (buffers, headers, etc...)
 *
 * Returns     :  Serial number for new certificate
 *
 *********************************************************************/
extern unsigned long get_certificate_serial(struct client_state *csp)
{
   unsigned long exp    = 1;
   unsigned long serial = 0;

   int i = CERT_SERIAL_NUM_LENGTH;

   for (; i >= 0; i--)
   {
      serial += exp * (unsigned)csp->http->hash_of_host[i];
      exp *= 256;
   }
   return serial;
}


/*********************************************************************
 *
 * Function    :  generate_certificate_valid_date
 *
 * Description :  Turns a time_t into the format expected by mbedTLS.
 *
 * Parameters  :
 *          1  :  time_spec = The timestamp to convert
 *          2  :  buffer = The buffer to write the date to
 *          3  :  buffer_size = The size of the buffer
 *          4  :  fmt = format
 *
 * Returns     :   0 => The conversion worked
 *                 1 => The conversion failed
 *
 *********************************************************************/
static int generate_certificate_valid_date(time_t time_spec, char *buffer,
                                           size_t buffer_size, const char *fmt)
{
   struct tm valid_date;
   struct tm *timeptr;
   size_t ret;

   timeptr = privoxy_gmtime_r(&time_spec, &valid_date);
   if (NULL == timeptr)
   {
      return 1;
   }

   ret = strftime(buffer, buffer_size, fmt, timeptr);
   if (ret <= 0)
   {
      return 1;
   }

   return 0;

}


/*********************************************************************
 *
 * Function    :  get_certificate_valid_from_date
 *
 * Description :  Generates a "valid from" date in the format
 *                expected by mbedTLS.
 *
 * Parameters  :
 *          1  :  buffer = The buffer to write the date to
 *          2  :  buffer_size = The size of the buffer
 *          3  :  fmt = format
 *
 * Returns     :   0 => The generation worked
 *                 1 => The generation failed
 *
 *********************************************************************/
extern int get_certificate_valid_from_date(char *buffer, size_t buffer_size, const char *fmt)
{
   time_t time_spec;

   time_spec = time(NULL);
   /* 1 month in the past */
   time_spec -= 30 * 24 * 60 * 60;

   return generate_certificate_valid_date(time_spec, buffer, buffer_size, fmt);

}


/*********************************************************************
 *
 * Function    :  get_certificate_valid_to_date
 *
 * Description :  Generates a "valid to" date in the format
 *                expected by mbedTLS.
 *
 * Parameters  :
 *          1  :  buffer = The buffer to write the date to
 *          2  :  buffer_size = The size of the buffer
 *          3  :  fmt = format
 *
 * Returns     :   0 => The generation worked
 *                 1 => The generation failed
 *
 *********************************************************************/
extern int get_certificate_valid_to_date(char *buffer, size_t buffer_size, const char *fmt)
{
   time_t time_spec;

   time_spec = time(NULL);
   /* Three months in the future */
   time_spec += 90 * 24 * 60 * 60;

   return generate_certificate_valid_date(time_spec, buffer, buffer_size, fmt);

}


/*********************************************************************
 *
 * Function    :  host_is_ip_address
 *
 * Description :  Checks whether or not a host is specified by
 *                IP address. Does not actually validate the
 *                address.
 *
 * Parameters  :
 *          1  :  host = The host name to check
 *
 * Returns     :   1 => Yes
 *                 0 => No
 *
 *********************************************************************/
extern int host_is_ip_address(const char *host)
{
   const char *p;

   if (NULL != strstr(host, ":"))
   {
      /* Assume an IPv6 address. */
      return 1;
   }

   for (p = host; *p; p++)
   {
      if ((*p != '.') && !privoxy_isdigit(*p))
      {
         /* Not a dot or digit so it can't be an IPv4 address. */
         return 0;
      }
   }

   /*
    * Host only consists of dots and digits so
    * assume that is an IPv4 address.
    */
   return 1;

}


/*********************************************************************
 *
 * Function    :  enforce_sane_certificate_state
 *
 * Description :  Makes sure the certificate state is sane.
 *
 * Parameters  :
 *          1  :  certificate = Path to the potentionally existing certifcate.
 *          2  :  key = Path to the potentionally existing key.
 *
 * Returns     :   -1 => Error
 *                 0 => Certificate state is sane
 *
 *********************************************************************/
extern int enforce_sane_certificate_state(const char *certificate, const char *key)
{
   const int certificate_exists = file_exists(certificate);
   const int key_exists = file_exists(key);

   if (!certificate_exists && key_exists)
   {
      log_error(LOG_LEVEL_ERROR,
         "A website key already exists but there's no matching certificate. "
         "Removing %s before creating a new key and certificate.", key);
      if (unlink(key))
      {
         log_error(LOG_LEVEL_ERROR, "Failed to unlink %s: %E", key);

         return -1;
      }
   }
   if (certificate_exists && !key_exists)
   {
      log_error(LOG_LEVEL_ERROR,
         "A certificate exists but there's no matching key. "
         "Removing %s before creating a new key and certificate.", certificate);
      if (unlink(certificate))
      {
         log_error(LOG_LEVEL_ERROR, "Failed to unlink %s: %E", certificate);

         return -1;
      }
   }

   return 0;

}