wind: Add a second unix socket for privileged clients which need to be in a different group

base/etc/group

@@ -1,4 +1,5 @@
 root:!:0:
 users:!:1:selene
 wind:!:2:selene
+wsys:!:3:
 selene:!:1000:

wind/Client.h

@@ -6,12 +6,13 @@ struct Client
 {
     os::LocalServer::Client conn;
     Vector<Window*> windows;
+    const bool privileged { false };
     bool rpc_in_progress { false };
     u8 rpc_id { 0 };
 
-    Client(os::LocalServer::Client&& client)
+    Client(os::LocalServer::Client&& client, bool priv)
 #ifdef CLIENT_IMPLEMENTATION
-        : conn(move(client)), windows() {}
+        : conn(move(client)), windows(), privileged(priv) {}
 #else
         ;
 #endif

wind/main.cpp

@@ -6,17 +6,14 @@
 #include "Screen.h"
 #include "Window.h"
 #include <errno.h>
-#include <grp.h>
 #include <moon/Keyboard.h>
 #include <os/ArgumentParser.h>
 #include <os/File.h>
 #include <os/LocalServer.h>
 #include <os/Process.h>
 #include <os/Security.h>
-#include <pwd.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/ioctl.h>
 #include <sys/poll.h>
 #include <sys/stat.h>
 #include <time.h>
@@ -24,6 +21,7 @@
 
 static constexpr uid_t WIND_USER_ID = 2;
 static constexpr gid_t WIND_GROUP_ID = 2;
+static constexpr gid_t WSYS_GROUP_ID = 3;
 
 static void debug(const Vector<OwnedPtr<Client>>& clients)
 {
@@ -63,11 +61,14 @@ Result<int> luna_main(int argc, char** argv)
     TRY(os::Security::pledge("stdio rpath wpath cpath unix proc exec tty id", NULL));
 
     StringView socket_path = "/tmp/wind.sock";
+    StringView system_socket_path = "/tmp/wsys.sock";
 
     os::ArgumentParser parser;
     parser.add_description("The display server for Luna's graphical user interface."_sv);
     parser.add_system_program_info("wind"_sv);
     parser.add_value_argument(socket_path, 's', "socket"_sv, "the path for the local IPC socket"_sv);
+    parser.add_value_argument(system_socket_path, ' ', "system-socket"_sv,
+                              "the path for the system IPC socket, for privileged clients"_sv);
     parser.parse(argc, argv);
 
     if (geteuid() != 0)
@@ -90,10 +91,24 @@ Result<int> luna_main(int argc, char** argv)
 
     Mouse mouse_pointer { screen.canvas() };
 
+    umask(0002);
+
+    // Set permissions to wind:wsys temporarily, to create /tmp/wsys.sock with those privileges.
+    setegid(WSYS_GROUP_ID);
+    seteuid(WIND_USER_ID);
+
+    auto system_server = TRY(os::LocalServer::create(system_socket_path, false));
+    TRY(system_server->listen(20));
+
+    seteuid(0);
+
     // Opened all necessary files as root, drop privileges now.
     setgid(WIND_GROUP_ID);
     setuid(WIND_USER_ID);
 
+    auto server = TRY(os::LocalServer::create(socket_path, false));
+    TRY(server->listen(20));
+
     int fd = open("/dev/null", O_RDONLY);
     if (fd >= 0)
     {
@@ -101,11 +116,6 @@ Result<int> luna_main(int argc, char** argv)
         close(fd);
     }
 
-    umask(0002);
-
-    auto server = TRY(os::LocalServer::create(socket_path, false));
-    TRY(server->listen(20));
-
     ui::Color background = ui::Color::from_rgb(0x10, 0x10, 0x10);
 
     Vector<OwnedPtr<Client>> clients;
@@ -113,6 +123,7 @@ Result<int> luna_main(int argc, char** argv)
     TRY(fds.try_append({ .fd = mouse->fd(), .events = POLLIN, .revents = 0 }));
     TRY(fds.try_append({ .fd = keyboard->fd(), .events = POLLIN, .revents = 0 }));
     TRY(fds.try_append({ .fd = server->fd(), .events = POLLIN, .revents = 0 }));
+    TRY(fds.try_append({ .fd = system_server->fd(), .events = POLLIN, .revents = 0 }));
 
     TRY(os::Security::pledge("stdio rpath wpath cpath unix proc exec", NULL));
 
@@ -148,13 +159,29 @@ Result<int> luna_main(int argc, char** argv)
                 os::IPC::send_async(window->client->conn, request);
             }
         }
+        if (fds[2].revents & POLLIN)
+        {
+            auto client = TRY(server->accept());
+            os::println("wind: New client connected!");
+            TRY(fds.try_append({ .fd = client.fd(), .events = POLLIN, .revents = 0 }));
+            OwnedPtr<Client> c = TRY(adopt_owned_if_nonnull(new Client(move(client), false)));
+            TRY(clients.try_append(move(c)));
+        }
+        if (fds[3].revents & POLLIN)
+        {
+            auto client = TRY(system_server->accept());
+            os::println("wind: New privileged client connected!");
+            TRY(fds.try_append({ .fd = client.fd(), .events = POLLIN, .revents = 0 }));
+            OwnedPtr<Client> c = TRY(adopt_owned_if_nonnull(new Client(move(client), true)));
+            TRY(clients.try_append(move(c)));
+        }
         for (usize i = 0; i < clients.size(); i++)
         {
-            if (fds[i + 3].revents & POLLIN) wind::handle_ipc(*clients[i]);
+            if (fds[i + 4].revents & POLLIN) wind::handle_ipc(*clients[i]);
-            if (fds[i + 3].revents & POLLHUP)
+            if (fds[i + 4].revents & POLLHUP)
             {
                 os::println("wind: Client %d disconnected", i);
-                fds.remove_at(i + 3);
+                fds.remove_at(i + 4);
                 auto client = clients.remove_at(i);
                 client->conn.disconnect();
                 for (auto& window : client->windows)
@@ -168,13 +195,5 @@ Result<int> luna_main(int argc, char** argv)
                 }
             }
         }
-        if (fds[2].revents & POLLIN)
-        {
-            auto client = TRY(server->accept());
-            os::println("wind: New client connected!");
-            TRY(fds.try_append({ .fd = client.fd(), .events = POLLIN, .revents = 0 }));
-            OwnedPtr<Client> c = TRY(adopt_owned_if_nonnull(new Client(move(client))));
-            TRY(clients.try_append(move(c)));
-        }
     }
 }