Kernel: Add "accept" pledge promise for accepting incoming connections

This patch adds a new "accept" promise that allows you to call accept()
on an already listening socket. This lets programs set up a socket for
for listening and then dropping "inet" and/or "unix" so that only
incoming (and existing) connections are allowed from that point on.
No new outgoing connections or listening server sockets can be created.

In addition to accept() it also allows getsockopt() with SOL_SOCKET
and SO_PEERCRED, which is used to find the PID/UID/GID of the socket
peer. This is used by our IPC library when creating shared buffers that
should only be accessible to a specific peer process.

This allows us to drop "unix" in WindowServer and LookupServer. :^)

It also makes the debugging/introspection RPC sockets in CEventLoop
based programs work again.

1 files changed, 2 insertions, 2 deletions

diff --git a/Servers/AudioServer/main.cpp b/Servers/AudioServer/main.cpp
index 496feb850c..3f76f04642 100644
--- a/Servers/AudioServer/main.cpp
+++ b/Servers/AudioServer/main.cpp
@@ -4,12 +4,12 @@
 
 int main(int, char**)
 {
-    if (pledge("stdio thread shared_buffer rpath wpath cpath unix fattr", nullptr) < 0) {
+    if (pledge("stdio thread shared_buffer accept rpath wpath cpath unix fattr", nullptr) < 0) {
         perror("pledge");
         return 1;
     }
     ASEventLoop event_loop;
-    if (pledge("stdio thread shared_buffer rpath wpath unix", nullptr) < 0) {
+    if (pledge("stdio thread shared_buffer accept rpath wpath", nullptr) < 0) {
         perror("pledge");
         return 1;
     }