libasteriskssl.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2009-2018, Digium, Inc.
 *
 * Russell Bryant <[email protected]>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*!
 * \file
 * \brief Common OpenSSL support code
 *
 * \author Russell Bryant <[email protected]>
 */

#include "asterisk.h"

#include "asterisk/_private.h"   /* ast_ssl_init() */

#ifdef HAVE_OPENSSL
#include <openssl/opensslv.h>    /* for OPENSSL_VERSION_NUMBER */
#endif

#if defined(HAVE_OPENSSL) && \
   (defined(LIBRESSL_VERSION_NUMBER) || OPENSSL_VERSION_NUMBER < 0x10100000L)

#include <dlfcn.h>               /* for dlerror, dlsym, RTLD_NEXT */
#include <openssl/crypto.h>      /* for CRYPTO_num_locks, CRYPTO_set_id_call... */
#include <openssl/err.h>         /* for ERR_free_strings */
#include <openssl/ssl.h>         /* for SSL_library_init, SSL_load_error_str... */
#if OPENSSL_VERSION_NUMBER < 0x10000000L
#include <pthread.h>             /* for pthread_self */
#endif

#include "asterisk/lock.h"       /* for ast_mutex_t, ast_mutex_init, ast_mut... */
#include "asterisk/logger.h"     /* for ast_debug, ast_log, LOG_ERROR */
#include "asterisk/utils.h"      /* for ast_calloc */

#define get_OpenSSL_function(func) do { real_##func = dlsym(RTLD_NEXT, __stringify(func)); } while(0)

static int startup_complete;

static ast_mutex_t *ssl_locks;

static int ssl_num_locks;

#if OPENSSL_VERSION_NUMBER < 0x10000000L
static unsigned long ssl_threadid(void)
{
   return (unsigned long) pthread_self();
}
#endif

static void ssl_lock(int mode, int n, const char *file, int line)
{
   if (n < 0 || n >= ssl_num_locks) {
      ast_log(LOG_ERROR, "OpenSSL is full of LIES!!! - "
            "ssl_num_locks '%d' - n '%d'\n",
            ssl_num_locks, n);
      return;
   }

   if (mode & 0x1) {
      ast_mutex_lock(&ssl_locks[n]);
   } else {
      ast_mutex_unlock(&ssl_locks[n]);
   }
}

int SSL_library_init(void)
{
#if defined(AST_DEVMODE)
   if (startup_complete) {
      ast_debug(1, "Called after startup... ignoring!\n");
   }
#endif
   return 1;
}

void SSL_load_error_strings(void)
{
#if defined(AST_DEVMODE)
   if (startup_complete) {
      ast_debug(1, "Called after startup... ignoring!\n");
   }
#endif
}

#if OPENSSL_VERSION_NUMBER < 0x10000000L
void CRYPTO_set_id_callback(unsigned long (*func)(void))
{
#if defined(AST_DEVMODE)
   if (startup_complete) {
      ast_debug(1, "Called after startup... ignoring!\n");
   }
#endif
}
#endif

void CRYPTO_set_locking_callback(void (*func)(int mode,int type, const char *file, int line))
{
#if defined(AST_DEVMODE)
   if (startup_complete) {
      ast_debug(1, "Called after startup... ignoring!\n");
   }
#endif
}

void ERR_free_strings(void)
{
   /* we can't allow this to be called, ever */
}

/*!
 * \internal
 * \brief Common OpenSSL initialization for all of Asterisk.
 *
 * Not needed for OpenSSL versions >= 1.1.0
 */
int ast_ssl_init(void)
{
   unsigned int i;
   int (*real_SSL_library_init)(void);
#if OPENSSL_VERSION_NUMBER < 0x10000000L
   void (*real_CRYPTO_set_id_callback)(unsigned long (*)(void));
#endif
   void (*real_CRYPTO_set_locking_callback)(void (*)(int, int, const char *, int));
   void (*real_SSL_load_error_strings)(void);
   const char *errstr;

   /* clear any previous dynamic linker errors */
   dlerror();
   get_OpenSSL_function(SSL_library_init);
   if ((errstr = dlerror()) != NULL) {
      ast_debug(1, "unable to get real address of SSL_library_init: %s\n", errstr);
      /* there is no way to continue in this situation... SSL will
       * likely be broken in this process
       */
      return -1;
   } else {
      real_SSL_library_init();
   }

   /* Make OpenSSL usage thread-safe. */

#if OPENSSL_VERSION_NUMBER < 0x10000000L
   dlerror();
   get_OpenSSL_function(CRYPTO_set_id_callback);
   if ((errstr = dlerror()) != NULL) {
      ast_debug(1, "unable to get real address of CRYPTO_set_id_callback: %s\n", errstr);
      /* there is no way to continue in this situation... SSL will
       * likely be broken in this process
       */
      return -1;
   } else {
      real_CRYPTO_set_id_callback(ssl_threadid);
   }
#endif

   dlerror();
   get_OpenSSL_function(CRYPTO_set_locking_callback);
   if ((errstr = dlerror()) != NULL) {
      ast_debug(1, "unable to get real address of CRYPTO_set_locking_callback: %s\n", errstr);
      /* there is no way to continue in this situation... SSL will
       * likely be broken in this process
       */
      return -1;
   } else {
      ssl_num_locks = CRYPTO_num_locks();
      if (!(ssl_locks = ast_calloc(ssl_num_locks, sizeof(ssl_locks[0])))) {
         return -1;
      }
      for (i = 0; i < ssl_num_locks; i++) {
         ast_mutex_init(&ssl_locks[i]);
      }
      real_CRYPTO_set_locking_callback(ssl_lock);
   }

   /* after this point, we don't check for errors from the dlsym() calls,
    * under the assumption that if the ones above were successful, all
    * the rest will be too. this assumption holds as long as OpenSSL still
    * provides all of these functions.
    */

   get_OpenSSL_function(SSL_load_error_strings);
   real_SSL_load_error_strings();

   startup_complete = 1;

   return 0;
}

#else

int ast_ssl_init(void)
{
   return 0;
}

#endif