s3:messages: protect against usage of wrapper tevent_context objects for messaging

This makes a lot of assumtion easier to understand and the introduction
of wrapper tevent contexts will not change the existing behaviour.

We'll relax this a bit in the next commits.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>

5 files changed, 69 insertions, 0 deletions

diff --git a/source3/lib/messages.c b/source3/lib/messages.c
index 82a177856f6..1a5ea4659aa 100644
--- a/source3/lib/messages.c
+++ b/source3/lib/messages.c
@@ -365,6 +365,11 @@ static bool messaging_alert_event_contexts(struct messaging_context *ctx)
 		 * alternatively would be to track whether the
 		 * immediate has already been scheduled. For
 		 * now, avoid that complexity here.
+		 *
+		 * reg->ev and ctx->event_ctx can't
+		 * be wrapper tevent_context pointers
+		 * so we don't need to use
+		 * tevent_context_same_loop().
 		 */
 
 		if (reg->ev == ctx->event_ctx) {
@@ -493,6 +498,12 @@ static NTSTATUS messaging_init_internal(TALLOC_CTX *mem_ctx,
 
 	sec_init();
 
+	if (tevent_context_is_wrapper(ev)) {
+		/* This is really a programmer error! */
+		DBG_ERR("Should not be used with a wrapper tevent context\n");
+		return NT_STATUS_INVALID_PARAMETER;
+	}
+
 	lck_path = lock_path("msg.lock");
 	if (lck_path == NULL) {
 		return NT_STATUS_NO_MEMORY;
@@ -1023,6 +1034,13 @@ struct tevent_req *messaging_filtered_read_send(
 	state->filter = filter;
 	state->private_data = private_data;
 
+	if (tevent_context_is_wrapper(ev)) {
+		/* This is really a programmer error! */
+		DBG_ERR("Wrapper tevent context doesn't use main context.\n");
+		tevent_req_error(req, EINVAL);
+		return tevent_req_post(req, ev);
+	}
+
 	/*
 	 * We have to defer the callback here, as we might be called from
 	 * within a different tevent_context than state->ev
@@ -1343,6 +1361,11 @@ static void messaging_dispatch_rec(struct messaging_context *msg_ctx,
 	bool consumed;
 	size_t i;
 
+	/*
+	 * ev and msg_ctx->event_ctx can't be wrapper tevent_context pointers
+	 * so we don't need to use tevent_context_same_loop().
+	 */
+
 	if (ev == msg_ctx->event_ctx) {
 		consumed = messaging_dispatch_classic(msg_ctx, rec);
 		if (consumed) {
diff --git a/source3/lib/messages_ctdb.c b/source3/lib/messages_ctdb.c
index d3e2e3f8589..a1aeb37af19 100644
--- a/source3/lib/messages_ctdb.c
+++ b/source3/lib/messages_ctdb.c
@@ -209,6 +209,14 @@ struct messaging_ctdb_fde *messaging_ctdb_register_tevent_context(
 		return NULL;
 	}
 
+	if (tevent_context_is_wrapper(ev)) {
+		/*
+		 * This is really a programmer error!
+		 */
+		DBG_ERR("Should not be used with a wrapper tevent context\n");
+		return NULL;
+	}
+
 	fde = talloc(mem_ctx, struct messaging_ctdb_fde);
 	if (fde == NULL) {
 		return NULL;
diff --git a/source3/lib/messages_ctdb_ref.c b/source3/lib/messages_ctdb_ref.c
index 3570ed8ae4c..47b4b758dac 100644
--- a/source3/lib/messages_ctdb_ref.c
+++ b/source3/lib/messages_ctdb_ref.c
@@ -52,6 +52,18 @@ void *messaging_ctdb_ref(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 {
 	struct msg_ctdb_ref *result, *tmp_refs;
 
+	if (tevent_context_is_wrapper(ev)) {
+		/*
+		 * This is really a programmer error!
+		 *
+		 * The main/raw tevent context should
+		 * have been registered first!
+		 */
+		DBG_ERR("Should not be used with a wrapper tevent context\n");
+		*err = EINVAL;
+		return NULL;
+	}
+
 	result = talloc(mem_ctx, struct msg_ctdb_ref);
 	if (result == NULL) {
 		*err = ENOMEM;
diff --git a/source3/lib/messages_dgm.c b/source3/lib/messages_dgm.c
index b8878b68b99..1c76615093c 100644
--- a/source3/lib/messages_dgm.c
+++ b/source3/lib/messages_dgm.c
@@ -993,6 +993,12 @@ int messaging_dgm_init(struct tevent_context *ev,
 		return EEXIST;
 	}
 
+	if (tevent_context_is_wrapper(ev)) {
+		/* This is really a programmer error! */
+		DBG_ERR("Should not be used with a wrapper tevent context\n");
+		return EINVAL;
+	}
+
 	ctx = talloc_zero(NULL, struct messaging_dgm_context);
 	if (ctx == NULL) {
 		goto fail_nomem;
@@ -1673,6 +1679,14 @@ struct messaging_dgm_fde *messaging_dgm_register_tevent_context(
 		return NULL;
 	}
 
+	if (tevent_context_is_wrapper(ev)) {
+		/*
+		 * This is really a programmer error!
+		 */
+		DBG_ERR("Should not be used with a wrapper tevent context\n");
+		return NULL;
+	}
+
 	fde = talloc(mem_ctx, struct messaging_dgm_fde);
 	if (fde == NULL) {
 		return NULL;
diff --git a/source3/lib/messages_dgm_ref.c b/source3/lib/messages_dgm_ref.c
index 470dfbeabc7..fd170961746 100644
--- a/source3/lib/messages_dgm_ref.c
+++ b/source3/lib/messages_dgm_ref.c
@@ -55,6 +55,18 @@ void *messaging_dgm_ref(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 {
 	struct msg_dgm_ref *result, *tmp_refs;
 
+	if (tevent_context_is_wrapper(ev)) {
+		/*
+		 * This is really a programmer error!
+		 *
+		 * The main/raw tevent context should
+		 * have been registered first!
+		 */
+		DBG_ERR("Should not be used with a wrapper tevent context\n");
+		*err = EINVAL;
+		return NULL;
+	}
+
 	result = talloc(mem_ctx, struct msg_dgm_ref);
 	if (result == NULL) {
 		*err = ENOMEM;