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authorStephen Gallagher <sgallagh@redhat.com>2012-06-22 11:25:33 -0400
committerStephen Gallagher <sgallagh@redhat.com>2012-06-22 11:25:33 -0400
commit28ad2dd0b12e695cb5bd47a9d87db550ffff1067 (patch)
tree37811c341c3232ff102ee849fa8ed5c308cd06cf
parenta824f629c40d9a77712681546ca989b894912a11 (diff)
downloadsssd-28ad2dd0b12e695cb5bd47a9d87db550ffff1067.tar.gz
sssd-28ad2dd0b12e695cb5bd47a9d87db550ffff1067.tar.xz
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DP: Reorganize memory hierarchy of requests
This function alters the memory hierarchy of the be_req to ensure memory safety during shutdown. It creates a spy on the be_cli object so that it will free the be_req if the client is freed. It is generally allocated atop the private data context for the appropriate back-end against which it is being filed. https://fedorahosted.org/sssd/ticket/1226
-rw-r--r--src/providers/data_provider_be.c115
1 files changed, 100 insertions, 15 deletions
diff --git a/src/providers/data_provider_be.c b/src/providers/data_provider_be.c
index 29124208a..7cf8b6ba4 100644
--- a/src/providers/data_provider_be.c
+++ b/src/providers/data_provider_be.c
@@ -121,28 +121,113 @@ static void be_async_req_handler(struct tevent_context *ev,
async_req->fn(async_req->req);
}
-static int be_file_request(struct be_ctx *ctx,
- be_req_fn_t fn,
- struct be_req *req)
+
+struct be_spy {
+ TALLOC_CTX *freectx;
+ struct be_spy *double_agent;
+};
+
+static int be_spy_destructor(struct be_spy *spy)
+{
+ /* If there's a double_agent, set its
+ * freectx to NULL so that we don't
+ * try to loop. When that spy fires,
+ * it will just be a no-op.
+ */
+ spy->double_agent->freectx = NULL;
+ talloc_zfree(spy->freectx);
+ return 0;
+}
+
+static errno_t be_spy_create(TALLOC_CTX *mem_ctx, struct be_req *be_req)
+{
+ errno_t ret;
+ struct be_spy *cli_spy = NULL;
+ struct be_spy *req_spy = NULL;
+
+ /* Attach a spy for the be_client so that if it dies,
+ * we can free the be_req automatically.
+ */
+ cli_spy = talloc_zero(be_req->becli, struct be_spy);
+ if (!cli_spy) {
+ ret = ENOMEM;
+ goto done;
+ }
+ cli_spy->freectx = mem_ctx;
+
+ /* Also create a spy on the be_req so that we
+ * can free the other spy when the be_req
+ * completes successfully.
+ */
+ req_spy = talloc_zero(be_req, struct be_spy);
+ if (!req_spy) {
+ ret = ENOMEM;
+ goto done;
+ }
+ req_spy->freectx = cli_spy;
+
+ /* Create paired spy links to prevent loops */
+ cli_spy->double_agent = req_spy;
+ req_spy->double_agent = cli_spy;
+
+ /* Now create the destructors that will actually free
+ * the opposing spies.
+ */
+ talloc_set_destructor(cli_spy, be_spy_destructor);
+ talloc_set_destructor(req_spy, be_spy_destructor);
+
+
+ /* Now steal the be_req onto the mem_ctx so that it
+ * will be guaranteed that this data will be
+ * available for the full duration of execution.
+ */
+ talloc_steal(mem_ctx, be_req);
+
+ ret = EOK;
+done:
+ if (ret != EOK) {
+ talloc_free(cli_spy);
+ talloc_free(req_spy);
+ }
+ return ret;
+}
+
+/* This function alters the memory hierarchy of the be_req
+ * to ensure memory safety during shutdown. It creates a
+ * spy on the be_cli object so that it will free the be_req
+ * if the client is freed.
+ *
+ * It is generally allocated atop the private data context
+ * for the appropriate back-end against which it is being
+ * filed.
+ */
+static int be_file_request(TALLOC_CTX *mem_ctx,
+ struct be_req *be_req,
+ be_req_fn_t fn)
{
+ errno_t ret;
struct be_async_req *areq;
struct tevent_timer *te;
struct timeval tv;
- if (!fn || !req) return EINVAL;
+ if (!fn || !be_req) return EINVAL;
+
+ ret = be_spy_create(mem_ctx, be_req);
+ if (ret != EOK) return ret;
- areq = talloc(req, struct be_async_req);
+ areq = talloc(be_req, struct be_async_req);
if (!areq) {
return ENOMEM;
}
areq->fn = fn;
- areq->req = req;
+ areq->req = be_req;
/* fire immediately */
tv.tv_sec = 0;
tv.tv_usec = 0;
- te = tevent_add_timer(ctx->ev, req, tv, be_async_req_handler, areq);
+ te = tevent_add_timer(be_req->be_ctx->ev, be_req,
+ tv, be_async_req_handler, areq);
if (te == NULL) {
return EIO;
}
@@ -446,9 +531,9 @@ static int be_get_account_info(DBusMessage *message, struct sbus_connection *con
be_req->req_data = req;
- ret = be_file_request(becli->bectx,
- becli->bectx->bet_info[BET_ID].bet_ops->handler,
- be_req);
+ ret = be_file_request(becli->bectx->bet_info[BET_ID].pvt_bet_data,
+ be_req,
+ becli->bectx->bet_info[BET_ID].bet_ops->handler);
if (ret != EOK) {
err_maj = DP_ERR_FATAL;
err_min = ret;
@@ -608,9 +693,9 @@ static int be_pam_handler(DBusMessage *message, struct sbus_connection *conn)
be_req->req_data = pd;
- ret = be_file_request(becli->bectx,
- becli->bectx->bet_info[target].bet_ops->handler,
- be_req);
+ ret = be_file_request(becli->bectx->bet_info[target].pvt_bet_data,
+ be_req,
+ becli->bectx->bet_info[target].bet_ops->handler);
if (ret != EOK) {
DEBUG(7, ("be_file_request failed.\n"));
goto done;
@@ -737,8 +822,8 @@ static errno_t be_file_check_online_request(struct be_req *req)
req->be_ctx->offstat.went_offline = time(NULL);
reset_fo(req->be_ctx);
- ret = be_file_request(req->be_ctx,
- req->be_ctx->bet_info[BET_ID].bet_ops->check_online, req);
+ ret = be_file_request(req->be_ctx, req,
+ req->be_ctx->bet_info[BET_ID].bet_ops->check_online);
if (ret != EOK) {
DEBUG(1, ("be_file_request failed.\n"));
}