[PATCH 1/9] kdbus: return EBADSLT on replies without slot

[David Herrmann <dh.herrmann@gmail.com>]

If you send a reply without an active reply slot, we used to return EPERM.
However, this makes it impossible to distinguish this case from a real
permission-denied error (eg., LSM). Hence, make sure we return a unique
error-code if the reply-slot is missing.

With this patch, you get EBADSLT ("Invalid slot") if you call
KDBUS_CMD_SEND with a reply-cookie that has no valid slot.

Reviewed-by: Daniel Mack <daniel@zonque.org>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
---
 ipc/kdbus/connection.c                       | 2 +-
 tools/testing/selftests/kdbus/test-message.c | 2 +-
 tools/testing/selftests/kdbus/test-sync.c    | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/ipc/kdbus/connection.c b/ipc/kdbus/connection.c
index d94b417..2787bd7 100644
--- a/ipc/kdbus/connection.c
+++ b/ipc/kdbus/connection.c
@@ -1123,7 +1123,7 @@ static int kdbus_conn_reply(struct kdbus_conn *src,
 	mutex_unlock(&dst->lock);
 
 	if (!reply) {
-		ret = -EPERM;
+		ret = -EBADSLT;
 		goto exit;
 	}
 
diff --git a/tools/testing/selftests/kdbus/test-message.c b/tools/testing/selftests/kdbus/test-message.c
index ddc1e0a..563dc85 100644
--- a/tools/testing/selftests/kdbus/test-message.c
+++ b/tools/testing/selftests/kdbus/test-message.c
@@ -75,7 +75,7 @@ int kdbus_test_message_basic(struct kdbus_test_env *env)
 
 	/* Faked replies with a valid reply cookie are rejected */
 	ret = kdbus_msg_send_reply(conn, time(NULL) ^ cookie, sender->id);
-	ASSERT_RETURN(ret == -EPERM);
+	ASSERT_RETURN(ret == -EBADSLT);
 
 	ret = kdbus_free(conn, offset);
 	ASSERT_RETURN(ret == 0);
diff --git a/tools/testing/selftests/kdbus/test-sync.c b/tools/testing/selftests/kdbus/test-sync.c
index e2be910..0655a54 100644
--- a/tools/testing/selftests/kdbus/test-sync.c
+++ b/tools/testing/selftests/kdbus/test-sync.c
@@ -235,7 +235,7 @@ static void *run_thread_reply(void *data)
 
 	/* using an unknown cookie must fail */
 	ret = kdbus_msg_send_reply(conn_a, ~cookie, conn_b->id);
-	if (ret != -EPERM) {
+	if (ret != -EBADSLT) {
 		status = TEST_ERR;
 		goto exit_thread;
 	}
-- 
2.5.0