Commit d7dad162 authored by Jacob Champion's avatar Jacob Champion
Browse files

PR60947: avoid CRYPTO_THREADID_set_callback() if possible 

CRYPTO_THREADID_set_callback() is write-once, so if mod_ssl is unloaded
and reloaded into a different address, we'll crash if OpenSSL wasn't
also unloaded and reloaded at the same time. This can happen if another
module or library is using OpenSSL as well.

- OpenSSL 1.1.0 isn't affected.
- Certain platforms (Windows, BeOS, and POSIX-compliant systems) can
  make use of the default THREADID callback in OpenSSL 1.0.x.
- If the deprecated CRYPTO_set_id_callback() is available, we can use it
  instead of CRYPTO_THREADID_set_callback().

Otherwise, we have to fall back to CRYPTO_THREADID_set_callback(), but
hopefully that applies to a small percentage of users at this point.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/trunk-openssl-threadid@1791732 13f79535-47bb-0310-9956-ffa450edef68
parent 55f312e4

acinclude.m4

+2 −1
Original line number Diff line number Diff line
@@ -608,7 +608,8 @@ AC_DEFUN([APACHE_CHECK_OPENSSL],[ 
      liberrors=""

      AC_CHECK_HEADERS([openssl/engine.h])

      AC_CHECK_FUNCS([SSL_CTX_new], [], [liberrors="yes"])

      AC_CHECK_FUNCS([ENGINE_init ENGINE_load_builtin_engines RAND_egd])

      AC_CHECK_FUNCS([ENGINE_init ENGINE_load_builtin_engines RAND_egd \

                      CRYPTO_set_id_callback])

      if test "x$liberrors" != "x"; then

        AC_MSG_WARN([OpenSSL libraries are unusable])

      fi

modules/ssl/ssl_util.c

+45 −22
Original line number Diff line number Diff line
@@ -252,6 +252,13 @@ void ssl_asn1_table_unset(apr_hash_t *table, 
 * To ensure thread-safetyness in OpenSSL - work in progress

 */



#if (OPENSSL_VERSION_NUMBER >= 0x10000000L) && \

        (_WIN32 || __BEOS__ || AP_OPENSSL_USE_ERRNO_THREADID)

/* Windows and BeOS can use the default THREADID callback shipped with OpenSSL

 * 1.0.x, as can any platform with a thread-safe errno. */

# define DEFAULT_THREADID_IS_SAFE 1

#endif



static apr_thread_mutex_t **lock_cs;

static int                  lock_num_locks;
@@ -363,6 +370,13 @@ static void ssl_dyn_destroy_function(struct CRYPTO_dynlock_value *l, 
    apr_pool_destroy(l->pool);

}



#if DEFAULT_THREADID_IS_SAFE



/* We don't need to set up a threadid callback on this platform. */

void ssl_util_thread_id_setup(apr_pool_t *p) { }



#else



/**

 * Used by both versions of ssl_util_thr_id(). Returns an unsigned long that

 * should be unique to the currently executing thread.
@@ -385,7 +399,14 @@ static unsigned long ssl_util_thr_id_internal(void) 
#endif

}



#if OPENSSL_VERSION_NUMBER >= 0x10000000L

#if HAVE_CRYPTO_SET_ID_CALLBACK



static unsigned long ssl_util_thr_id(void)

{

    return ssl_util_thr_id_internal();

}



#else



static void ssl_util_thr_id(CRYPTO_THREADID *id)

{
@@ -396,27 +417,39 @@ static void ssl_util_thr_id(CRYPTO_THREADID *id) 
    CRYPTO_THREADID_set_numeric(id, ssl_util_thr_id_internal());

}



#else



static unsigned long ssl_util_thr_id(void)

{

    return ssl_util_thr_id_internal();

}



#endif

#endif /* HAVE_CRYPTO_SET_ID_CALLBACK */



static apr_status_t ssl_util_thr_id_cleanup(void *old)

{

#if OPENSSL_VERSION_NUMBER >= 0x10000000L

#if HAVE_CRYPTO_SET_ID_CALLBACK

    CRYPTO_set_id_callback(old);

#else

    /* XXX This does nothing. The new-style THREADID callback is write-once. */

    CRYPTO_THREADID_set_callback(old);

#else

    CRYPTO_set_id_callback(old);

#endif



    return APR_SUCCESS;

}



void ssl_util_thread_id_setup(apr_pool_t *p)

{

#if HAVE_CRYPTO_SET_ID_CALLBACK

    /* This API is deprecated, but we prefer it to its replacement since it

     * allows us to unset the callback when this module is being unloaded. */

    CRYPTO_set_id_callback(ssl_util_thr_id);

#else

    /* This is a last resort. We can only set this once, which means that we'd

     * better not get loaded into a different address during a restart. See

     * PR60947. */

    CRYPTO_THREADID_set_callback(ssl_util_thr_id);

#endif



    apr_pool_cleanup_register(p, NULL, ssl_util_thr_id_cleanup,

                                       apr_pool_cleanup_null);

}



#endif /* DEFAULT_THREADID_IS_SAFE */



static apr_status_t ssl_util_thread_cleanup(void *data)

{

    CRYPTO_set_locking_callback(NULL);
@@ -457,15 +490,5 @@ void ssl_util_thread_setup(apr_pool_t *p) 
                                       apr_pool_cleanup_null);

}



void ssl_util_thread_id_setup(apr_pool_t *p)

{

#if OPENSSL_VERSION_NUMBER >= 0x10000000L

    CRYPTO_THREADID_set_callback(ssl_util_thr_id);

#else

    CRYPTO_set_id_callback(ssl_util_thr_id);

#endif

    apr_pool_cleanup_register(p, NULL, ssl_util_thr_id_cleanup,

                                       apr_pool_cleanup_null);

}

#endif /* #if OPENSSL_VERSION_NUMBER < 0x10100000L */

#endif /* #if APR_HAS_THREADS */