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nsswitch/wb_common.c: fix socket fd and memory leaks of global state
When we are called in wb_atfork_child() or winbind_destructor(), wb_thread_ctx_destructor() is not called for the global state of the current nor any other thread, which means we would leak the related memory and socket fds. Now we maintain a global list protected by a global mutex. We traverse the list and close all socket fds, which are no longer used (winbind_destructor) or no longer valid in the current process (wb_atfork_child), in addition we 'autofree' the ones, which are only visible internally as global (per thread) context. BUG: https://bugzilla.samba.org/show_bug.cgi?id=15464 Tested-by: Krzysztof Piotr Oledzki <ole@ans.pl> Signed-off-by: Stefan Metzmacher <metze@samba.org> Reviewed-by: Jeremy Allison <jra@samba.org> Autobuild-User(master): Stefan Metzmacher <metze@samba.org> Autobuild-Date(master): Thu Sep 14 18:53:07 UTC 2023 on atb-devel-224
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@ -26,6 +26,7 @@
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#include "replace.h"
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#include "system/select.h"
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#include "winbind_client.h"
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#include "lib/util/dlinklist.h"
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#include <assert.h>
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#ifdef HAVE_PTHREAD_H
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@ -37,67 +38,112 @@ static __thread char client_name[32];
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/* Global context */
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struct winbindd_context {
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struct winbindd_context *prev, *next;
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int winbindd_fd; /* winbind file descriptor */
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bool is_privileged; /* using the privileged socket? */
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pid_t our_pid; /* calling process pid */
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bool autofree; /* this is a thread global context */
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};
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static struct wb_global_ctx {
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bool initialized;
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#ifdef HAVE_PTHREAD
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pthread_once_t control;
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pthread_key_t key;
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bool key_initialized;
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#ifdef PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP
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#define WB_GLOBAL_MUTEX_INITIALIZER PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP
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#else
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bool dummy;
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#define WB_GLOBAL_MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER
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#endif
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#define WB_GLOBAL_LIST_LOCK do { \
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int __pret = pthread_mutex_lock(&wb_global_ctx.list_mutex); \
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assert(__pret == 0); \
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} while(0)
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#define WB_GLOBAL_LIST_UNLOCK do { \
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int __pret = pthread_mutex_unlock(&wb_global_ctx.list_mutex); \
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assert(__pret == 0); \
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} while(0)
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pthread_mutex_t list_mutex;
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#else /* => not HAVE_PTHREAD */
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#define WB_GLOBAL_LIST_LOCK do { } while(0)
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#define WB_GLOBAL_LIST_UNLOCK do { } while(0)
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#endif /* not HAVE_PTHREAD */
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struct winbindd_context *list;
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} wb_global_ctx = {
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#ifdef HAVE_PTHREAD
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.control = PTHREAD_ONCE_INIT,
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.list_mutex = WB_GLOBAL_MUTEX_INITIALIZER,
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#endif
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.list = NULL,
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};
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static void winbind_close_sock(struct winbindd_context *ctx);
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static void winbind_ctx_free_locked(struct winbindd_context *ctx);
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static void winbind_cleanup_list(void);
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#ifdef HAVE_PTHREAD
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static void wb_thread_ctx_initialize(void);
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static void wb_atfork_child(void)
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static void wb_atfork_prepare(void)
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{
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struct winbindd_context *ctx = NULL;
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int ret;
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ctx = (struct winbindd_context *)pthread_getspecific(wb_global_ctx.key);
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if (ctx == NULL) {
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return;
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WB_GLOBAL_LIST_LOCK;
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}
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static void wb_atfork_parent(void)
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{
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WB_GLOBAL_LIST_UNLOCK;
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}
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static void wb_atfork_child(void)
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{
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wb_global_ctx.list_mutex = (pthread_mutex_t)WB_GLOBAL_MUTEX_INITIALIZER;
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if (wb_global_ctx.key_initialized) {
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int ret;
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/*
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* After a fork the child still believes
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* it is the same thread as in the parent.
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* So pthread_getspecific() would return the
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* value of the thread that called fork().
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*
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* But we don't want that behavior, so
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* we just clear the reference and let
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* winbind_cleanup_list() below 'autofree'
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* the parent threads global context.
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*/
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ret = pthread_setspecific(wb_global_ctx.key, NULL);
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assert(ret == 0);
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}
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winbind_close_sock(ctx);
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free(ctx);
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/*
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* But we need to close/cleanup the global state
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* of the parents threads.
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*/
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winbind_cleanup_list();
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}
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static void wb_thread_ctx_destructor(void *p)
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{
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struct winbindd_context *ctx = (struct winbindd_context *)p;
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winbind_close_sock(ctx);
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free(ctx);
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winbindd_ctx_free(ctx);
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}
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static void wb_thread_ctx_initialize(void)
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{
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int ret;
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ret = pthread_atfork(NULL,
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NULL,
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ret = pthread_atfork(wb_atfork_prepare,
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wb_atfork_parent,
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wb_atfork_child);
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assert(ret == 0);
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ret = pthread_key_create(&wb_global_ctx.key,
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wb_thread_ctx_destructor);
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assert(ret == 0);
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wb_global_ctx.key_initialized = true;
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}
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static struct winbindd_context *get_wb_thread_ctx(void)
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@ -123,9 +169,14 @@ static struct winbindd_context *get_wb_thread_ctx(void)
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*ctx = (struct winbindd_context) {
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.winbindd_fd = -1,
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.is_privileged = false,
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.our_pid = 0
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.our_pid = 0,
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.autofree = true,
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};
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WB_GLOBAL_LIST_LOCK;
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DLIST_ADD_END(wb_global_ctx.list, ctx);
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WB_GLOBAL_LIST_UNLOCK;
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ret = pthread_setspecific(wb_global_ctx.key, ctx);
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if (ret != 0) {
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free(ctx);
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@ -142,7 +193,8 @@ static struct winbindd_context *get_wb_global_ctx(void)
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static struct winbindd_context _ctx = {
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.winbindd_fd = -1,
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.is_privileged = false,
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.our_pid = 0
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.our_pid = 0,
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.autofree = false,
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};
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#endif
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@ -150,9 +202,11 @@ static struct winbindd_context *get_wb_global_ctx(void)
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ctx = get_wb_thread_ctx();
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#else
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ctx = &_ctx;
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if (ctx->prev == NULL && ctx->next == NULL) {
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DLIST_ADD_END(wb_global_ctx.list, ctx);
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}
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#endif
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wb_global_ctx.initialized = true;
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return ctx;
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}
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@ -226,6 +280,30 @@ static void winbind_close_sock(struct winbindd_context *ctx)
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}
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}
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static void winbind_ctx_free_locked(struct winbindd_context *ctx)
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{
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winbind_close_sock(ctx);
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DLIST_REMOVE(wb_global_ctx.list, ctx);
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free(ctx);
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}
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static void winbind_cleanup_list(void)
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{
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struct winbindd_context *ctx = NULL, *next = NULL;
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WB_GLOBAL_LIST_LOCK;
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for (ctx = wb_global_ctx.list; ctx != NULL; ctx = next) {
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next = ctx->next;
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if (ctx->autofree) {
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winbind_ctx_free_locked(ctx);
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} else {
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winbind_close_sock(ctx);
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}
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}
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WB_GLOBAL_LIST_UNLOCK;
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}
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/* Destructor for global context to ensure fd is closed */
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#ifdef HAVE_DESTRUCTOR_ATTRIBUTE
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@ -235,18 +313,18 @@ __attribute__((destructor))
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#endif
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static void winbind_destructor(void)
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{
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struct winbindd_context *ctx;
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if (!wb_global_ctx.initialized) {
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return;
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#ifdef HAVE_PTHREAD
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if (wb_global_ctx.key_initialized) {
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int ret;
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ret = pthread_key_delete(wb_global_ctx.key);
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assert(ret == 0);
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wb_global_ctx.key_initialized = false;
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}
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ctx = get_wb_global_ctx();
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if (ctx == NULL) {
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return;
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}
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wb_global_ctx.control = (pthread_once_t)PTHREAD_ONCE_INIT;
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#endif /* HAVE_PTHREAD */
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winbind_close_sock(ctx);
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winbind_cleanup_list();
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}
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#define CONNECT_TIMEOUT 30
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@ -928,11 +1006,16 @@ struct winbindd_context *winbindd_ctx_create(void)
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ctx->winbindd_fd = -1;
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WB_GLOBAL_LIST_LOCK;
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DLIST_ADD_END(wb_global_ctx.list, ctx);
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WB_GLOBAL_LIST_UNLOCK;
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return ctx;
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}
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void winbindd_ctx_free(struct winbindd_context *ctx)
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{
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winbind_close_sock(ctx);
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free(ctx);
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WB_GLOBAL_LIST_LOCK;
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winbind_ctx_free_locked(ctx);
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WB_GLOBAL_LIST_UNLOCK;
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}
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