Magnus Hagander wrote:
> > Your analysis of this problem is right on target. When the SSL
> > callbacks were implemented for threaded libpq, there was never any
> > thought on the effect of unloading libpq while the callbacks were still
> > registered.
> >
> > The attached patch unregisters the callback on the close of the last
> > libpq connection. Fortunately we require PQfinish() even if the
> > connection request failed, meaning there should be proper accounting of
> > the number of open connections with the method used in this patch.
> >
> > We do leak some memory for every load/unload of libpq, but the leaks
> > extend beyond the SSL code to the rest of libpq so I didn't attempt to
> > address that in this patch (and no one has complained about it).
> >
> > I also could have implemented a function to unload the SSL callbacks.
> > It would have to have been called before libpq was unloaded, but I
> > considered it inconvenient and unlikely to be adopted by applications
> > using libpq in the short-term.
>
> I don't see why destroy_ssl_system sets up it's own mutex (that's also
> called init_mutex). I think it'd make more sense to make the mutex
> created in init_ssl_system() visible to the destroy function, and make
> use of that one instead. You'll need to somehow interlock against these
> two functions running on different threads after all.
>
>
> Also, the code for destroying/unlinking appears to never be called.. The
> callchain ends in pqsecure_destroy(), which is never called.
Thanks for the review, Magnus. I have adjusted the patch to use the
same mutex every time the counter is accessed, and adjusted the
pqsecure_destroy() call to properly decrement in the right place.
Also, I renamed the libpq global destroy function to be clearer
(the function is not exported).
--
Bruce Momjian <[EMAIL PROTECTED]> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
Index: src/backend/libpq/be-secure.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/libpq/be-secure.c,v
retrieving revision 1.85
diff -c -c -r1.85 be-secure.c
*** src/backend/libpq/be-secure.c 24 Oct 2008 12:24:35 -0000 1.85
--- src/backend/libpq/be-secure.c 5 Nov 2008 04:21:14 -0000
***************
*** 88,94 ****
static int verify_cb(int, X509_STORE_CTX *);
static void info_cb(const SSL *ssl, int type, int args);
static void initialize_SSL(void);
- static void destroy_SSL(void);
static int open_server_SSL(Port *);
static void close_SSL(Port *);
static const char *SSLerrmessage(void);
--- 88,93 ----
***************
*** 191,206 ****
return 0;
}
/*
* Destroy global context
*/
void
secure_destroy(void)
{
- #ifdef USE_SSL
- destroy_SSL();
- #endif
}
/*
* Attempt to negotiate secure session.
--- 190,204 ----
return 0;
}
+ #ifdef NOT_USED
/*
* Destroy global context
*/
void
secure_destroy(void)
{
}
+ #endif
/*
* Attempt to negotiate secure session.
***************
*** 805,815 ****
}
}
/*
! * Destroy global SSL context.
*/
static void
! destroy_SSL(void)
{
if (SSL_context)
{
--- 803,814 ----
}
}
+ #ifdef NOT_USED
/*
! * Destroy global SSL context
*/
static void
! destroy_global_SSL(void)
{
if (SSL_context)
{
***************
*** 817,822 ****
--- 816,822 ----
SSL_context = NULL;
}
}
+ #endif
/*
* Attempt to negotiate SSL connection.
Index: src/interfaces/libpq/fe-secure.c
===================================================================
RCS file: /cvsroot/pgsql/src/interfaces/libpq/fe-secure.c,v
retrieving revision 1.106
diff -c -c -r1.106 fe-secure.c
*** src/interfaces/libpq/fe-secure.c 24 Oct 2008 12:29:11 -0000 1.106
--- src/interfaces/libpq/fe-secure.c 5 Nov 2008 04:21:16 -0000
***************
*** 93,98 ****
--- 93,99 ----
static int verify_cb(int ok, X509_STORE_CTX *ctx);
static int client_cert_cb(SSL *, X509 **, EVP_PKEY **);
static int init_ssl_system(PGconn *conn);
+ static void destroy_ssl_system(void);
static int initialize_SSL(PGconn *);
static void destroy_SSL(void);
static PostgresPollingStatusType open_client_SSL(PGconn *);
***************
*** 105,110 ****
--- 106,122 ----
static bool pq_initssllib = true;
static SSL_CTX *SSL_context = NULL;
+
+ #ifdef ENABLE_THREAD_SAFETY
+ static int ssl_open_connections = 0;
+
+ #ifndef WIN32
+ static pthread_mutex_t ssl_config_mutex = PTHREAD_MUTEX_INITIALIZER;
+ #else
+ static pthread_mutex_t ssl_config_mutex = NULL;
+ static long win32_ssl_create_mutex = 0;
+ #endif
+
#endif
/*
***************
*** 760,805 ****
init_ssl_system(PGconn *conn)
{
#ifdef ENABLE_THREAD_SAFETY
! #ifndef WIN32
! static pthread_mutex_t init_mutex = PTHREAD_MUTEX_INITIALIZER;
! #else
! static pthread_mutex_t init_mutex = NULL;
! static long mutex_initlock = 0;
!
! if (init_mutex == NULL)
{
! while (InterlockedExchange(&mutex_initlock, 1) == 1)
/* loop, another thread own the lock */ ;
! if (init_mutex == NULL)
{
! if (pthread_mutex_init(&init_mutex, NULL))
return -1;
}
! InterlockedExchange(&mutex_initlock, 0);
}
#endif
! if (pthread_mutex_lock(&init_mutex))
return -1;
! if (pq_initssllib && pq_lockarray == NULL)
{
! int i;
!
! CRYPTO_set_id_callback(pq_threadidcallback);
!
! pq_lockarray = malloc(sizeof(pthread_mutex_t) * CRYPTO_num_locks());
! if (!pq_lockarray)
{
! pthread_mutex_unlock(&init_mutex);
! return -1;
}
! for (i = 0; i < CRYPTO_num_locks(); i++)
{
! if (pthread_mutex_init(&pq_lockarray[i], NULL))
! return -1;
}
-
- CRYPTO_set_locking_callback(pq_lockingcallback);
}
#endif
if (!SSL_context)
--- 772,822 ----
init_ssl_system(PGconn *conn)
{
#ifdef ENABLE_THREAD_SAFETY
! #ifdef WIN32
! if (ssl_config_mutex == NULL)
{
! while (InterlockedExchange(&win32_ssl_create_mutex, 1) == 1)
/* loop, another thread own the lock */ ;
! if (ssl_config_mutex == NULL)
{
! if (pthread_mutex_init(&ssl_config_mutex, NULL))
return -1;
}
! InterlockedExchange(&win32_ssl_create_mutex, 0);
}
#endif
! if (pthread_mutex_lock(&ssl_config_mutex))
return -1;
! if (pq_initssllib)
{
! if (pq_lockarray == NULL)
{
! int i;
!
! pq_lockarray = malloc(sizeof(pthread_mutex_t) * CRYPTO_num_locks());
! if (!pq_lockarray)
! {
! pthread_mutex_unlock(&ssl_config_mutex);
! return -1;
! }
! for (i = 0; i < CRYPTO_num_locks(); i++)
! {
! if (pthread_mutex_init(&pq_lockarray[i], NULL))
! {
! free(pq_lockarray);
! pq_lockarray = NULL;
! pthread_mutex_unlock(&ssl_config_mutex);
! return -1;
! }
! }
}
!
! if (ssl_open_connections++ == 0)
{
! CRYPTO_set_id_callback(pq_threadidcallback);
! CRYPTO_set_locking_callback(pq_lockingcallback);
}
}
#endif
if (!SSL_context)
***************
*** 822,839 ****
err);
SSLerrfree(err);
#ifdef ENABLE_THREAD_SAFETY
! pthread_mutex_unlock(&init_mutex);
#endif
return -1;
}
}
#ifdef ENABLE_THREAD_SAFETY
! pthread_mutex_unlock(&init_mutex);
#endif
return 0;
}
/*
* Initialize global SSL context.
*/
static int
--- 839,898 ----
err);
SSLerrfree(err);
#ifdef ENABLE_THREAD_SAFETY
! pthread_mutex_unlock(&ssl_config_mutex);
#endif
return -1;
}
}
#ifdef ENABLE_THREAD_SAFETY
! pthread_mutex_unlock(&ssl_config_mutex);
#endif
return 0;
}
/*
+ * This function is needed because if the libpq library is unloaded
+ * from the application, the callback functions will no longer exist when
+ * SSL used by other parts of the system. For this reason,
+ * we unregister the SSL callback functions when the last libpq
+ * connection is closed.
+ */
+ static void
+ destroy_ssl_system(void)
+ {
+ /* Assume mutex already created */
+ if (pthread_mutex_lock(&ssl_config_mutex))
+ return;
+
+ if (pq_initssllib)
+ {
+ /*
+ * We never free pq_lockarray, which means we leak memory on
+ * repeated loading/unloading of this library.
+ */
+
+ if (ssl_open_connections > 0)
+ --ssl_open_connections;
+
+ if (ssl_open_connections == 0)
+ {
+ /*
+ * We need to unregister the SSL callbacks on last connection
+ * close because the libpq shared library might be unloaded,
+ * and once it is, callbacks must be removed to prevent them
+ * from being called by other SSL code.
+ */
+ CRYPTO_set_locking_callback(NULL);
+ CRYPTO_set_id_callback(NULL);
+ }
+ }
+
+ pthread_mutex_unlock(&ssl_config_mutex);
+ #endif
+ return;
+ }
+
+ /*
* Initialize global SSL context.
*/
static int
***************
*** 897,907 ****
return 0;
}
/*
! * Destroy global SSL context.
*/
static void
! destroy_SSL(void)
{
if (SSL_context)
{
--- 956,973 ----
return 0;
}
+ static void
+ destroy_SSL(void)
+ {
+ destroy_ssl_system();
+ }
+
+ #ifdef NOT_USED
/*
! * Destroy global SSL context
*/
static void
! destroy_global_SSL(void)
{
if (SSL_context)
{
***************
*** 909,914 ****
--- 975,981 ----
SSL_context = NULL;
}
}
+ #endif
/*
* Attempt to negotiate SSL connection.
***************
*** 1028,1033 ****
--- 1095,1102 ----
SSL_shutdown(conn->ssl);
SSL_free(conn->ssl);
conn->ssl = NULL;
+ /* We have to do the destroy here while we are closing SSL */
+ pqsecure_destroy();
/* We have to assume we got EPIPE */
REMEMBER_EPIPE(true);
RESTORE_SIGPIPE();
--
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