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nsswitch/wb_common.c: fix socket fd and memory leaks of global state

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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longer used (winbind_destructor) or no longer valid in the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
This commit is contained in:
Stefan Metzmacher 2023-09-07 15:59:59 +02:00
parent 91b30a7261
commit 4af3faace4
1 changed files with 113 additions and 30 deletions
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143
nsswitch/wb_common.c
View File

@ -26,6 +26,7 @@
#include "replace.h"
#include "system/select.h"
#include "winbind_client.h"
#include "lib/util/dlinklist.h"
#include <assert.h>
#ifdef HAVE_PTHREAD_H
@ -37,67 +38,112 @@ static __thread char client_name[32];
/* Global context */
struct winbindd_context {
struct winbindd_context *prev, *next;
int winbindd_fd; /* winbind file descriptor */
bool is_privileged; /* using the privileged socket? */
pid_t our_pid; /* calling process pid */
bool autofree; /* this is a thread global context */
};
static struct wb_global_ctx {
bool initialized;
#ifdef HAVE_PTHREAD
pthread_once_t control;
pthread_key_t key;
bool key_initialized;
#ifdef PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP
#define WB_GLOBAL_MUTEX_INITIALIZER PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP
#else
bool dummy;
#define WB_GLOBAL_MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER
#endif
#define WB_GLOBAL_LIST_LOCK do { \
int __pret = pthread_mutex_lock(&wb_global_ctx.list_mutex); \
assert(__pret == 0); \
} while(0)
#define WB_GLOBAL_LIST_UNLOCK do { \
int __pret = pthread_mutex_unlock(&wb_global_ctx.list_mutex); \
assert(__pret == 0); \
} while(0)
pthread_mutex_t list_mutex;
#else /* => not HAVE_PTHREAD */
#define WB_GLOBAL_LIST_LOCK do { } while(0)
#define WB_GLOBAL_LIST_UNLOCK do { } while(0)
#endif /* not HAVE_PTHREAD */
struct winbindd_context *list;
} wb_global_ctx = {
#ifdef HAVE_PTHREAD
.control = PTHREAD_ONCE_INIT,
.list_mutex = WB_GLOBAL_MUTEX_INITIALIZER,
#endif
.list = NULL,
};
static void winbind_close_sock(struct winbindd_context *ctx);
static void winbind_ctx_free_locked(struct winbindd_context *ctx);
static void winbind_cleanup_list(void);
#ifdef HAVE_PTHREAD
static void wb_thread_ctx_initialize(void);
static void wb_atfork_prepare(void)
{
WB_GLOBAL_LIST_LOCK;
}
static void wb_atfork_parent(void)
{
WB_GLOBAL_LIST_UNLOCK;
}
static void wb_atfork_child(void)
{
struct winbindd_context *ctx = NULL;
int ret;
wb_global_ctx.list_mutex = (pthread_mutex_t)WB_GLOBAL_MUTEX_INITIALIZER;
ctx = (struct winbindd_context *)pthread_getspecific(wb_global_ctx.key);
if (ctx == NULL) {
return;
if (wb_global_ctx.key_initialized) {
int ret;
/*
* After a fork the child still believes
* it is the same thread as in the parent.
* So pthread_getspecific() would return the
* value of the thread that called fork().
*
* But we don't want that behavior, so
* we just clear the reference and let
* winbind_cleanup_list() below 'autofree'
* the parent threads global context.
*/
ret = pthread_setspecific(wb_global_ctx.key, NULL);
assert(ret == 0);
}
ret = pthread_setspecific(wb_global_ctx.key, NULL);
assert(ret == 0);
winbind_close_sock(ctx);
free(ctx);
/*
* But we need to close/cleanup the global state
* of the parents threads.
*/
winbind_cleanup_list();
}
static void wb_thread_ctx_destructor(void *p)
{
struct winbindd_context *ctx = (struct winbindd_context *)p;
winbind_close_sock(ctx);
free(ctx);
winbindd_ctx_free(ctx);
}
static void wb_thread_ctx_initialize(void)
{
int ret;
ret = pthread_atfork(NULL,
NULL,
ret = pthread_atfork(wb_atfork_prepare,
wb_atfork_parent,
wb_atfork_child);
assert(ret == 0);
ret = pthread_key_create(&wb_global_ctx.key,
wb_thread_ctx_destructor);
assert(ret == 0);
wb_global_ctx.key_initialized = true;
}
static struct winbindd_context *get_wb_thread_ctx(void)
@ -123,9 +169,14 @@ static struct winbindd_context *get_wb_thread_ctx(void)
*ctx = (struct winbindd_context) {
.winbindd_fd = -1,
.is_privileged = false,
.our_pid = 0
.our_pid = 0,
.autofree = true,
};
WB_GLOBAL_LIST_LOCK;
DLIST_ADD_END(wb_global_ctx.list, ctx);
WB_GLOBAL_LIST_UNLOCK;
ret = pthread_setspecific(wb_global_ctx.key, ctx);
if (ret != 0) {
free(ctx);
@ -142,7 +193,8 @@ static struct winbindd_context *get_wb_global_ctx(void)
static struct winbindd_context _ctx = {
.winbindd_fd = -1,
.is_privileged = false,
.our_pid = 0
.our_pid = 0,
.autofree = false,
};
#endif
@ -150,9 +202,11 @@ static struct winbindd_context *get_wb_global_ctx(void)
ctx = get_wb_thread_ctx();
#else
ctx = &_ctx;
if (ctx->prev == NULL && ctx->next == NULL) {
DLIST_ADD_END(wb_global_ctx.list, ctx);
}
#endif
wb_global_ctx.initialized = true;
return ctx;
}
@ -226,6 +280,30 @@ static void winbind_close_sock(struct winbindd_context *ctx)
}
}
static void winbind_ctx_free_locked(struct winbindd_context *ctx)
{
winbind_close_sock(ctx);
DLIST_REMOVE(wb_global_ctx.list, ctx);
free(ctx);
}
static void winbind_cleanup_list(void)
{
struct winbindd_context *ctx = NULL, *next = NULL;
WB_GLOBAL_LIST_LOCK;
for (ctx = wb_global_ctx.list; ctx != NULL; ctx = next) {
next = ctx->next;
if (ctx->autofree) {
winbind_ctx_free_locked(ctx);
} else {
winbind_close_sock(ctx);
}
}
WB_GLOBAL_LIST_UNLOCK;
}
/* Destructor for global context to ensure fd is closed */
#ifdef HAVE_DESTRUCTOR_ATTRIBUTE
@ -235,18 +313,18 @@ __attribute__((destructor))
#endif
static void winbind_destructor(void)
{
struct winbindd_context *ctx;
if (!wb_global_ctx.initialized) {
return;
#ifdef HAVE_PTHREAD
if (wb_global_ctx.key_initialized) {
int ret;
ret = pthread_key_delete(wb_global_ctx.key);
assert(ret == 0);
wb_global_ctx.key_initialized = false;
}
ctx = get_wb_global_ctx();
if (ctx == NULL) {
return;
}
wb_global_ctx.control = (pthread_once_t)PTHREAD_ONCE_INIT;
#endif /* HAVE_PTHREAD */
winbind_close_sock(ctx);
winbind_cleanup_list();
}
#define CONNECT_TIMEOUT 30
@ -928,11 +1006,16 @@ struct winbindd_context *winbindd_ctx_create(void)
ctx->winbindd_fd = -1;
WB_GLOBAL_LIST_LOCK;
DLIST_ADD_END(wb_global_ctx.list, ctx);
WB_GLOBAL_LIST_UNLOCK;
return ctx;
}
void winbindd_ctx_free(struct winbindd_context *ctx)
{
winbind_close_sock(ctx);
free(ctx);
WB_GLOBAL_LIST_LOCK;
winbind_ctx_free_locked(ctx);
WB_GLOBAL_LIST_UNLOCK;
}