Refuse to start when SUID is detected

This ensures that those surprised by the deprecation of SUID operation
receive an error rather than accidentally having run as root.

swaywm/sway@e572805

diff --git a/src/main.c b/src/main.c
index 04d020cb950935feb3c300d82a56da41fcab1d64..b7d7bbb3d27f77b346e7bc37c0b20a06f9fb17f1 100644 (file)
--- a/src/main.c
+++ b/src/main.c
@@ -47,6 +47,19 @@ usage(void)
        exit(0);
 }
 
+static void
+die_on_detecting_suid(void)
+{
+       if (geteuid() != 0 && getegid() != 0) {
+               return;
+       }
+       if (getuid() == geteuid() && getgid() == getegid()) {
+               return;
+       }
+       wlr_log(WLR_ERROR, "SUID detected - aborting");
+       exit(EXIT_FAILURE);
+}
+
 static void
 send_signal_to_labwc_pid(int signal)
 {
@@ -118,6 +131,8 @@ main(int argc, char *argv[])
 
        wlr_log_init(verbosity, NULL);
 
+       die_on_detecting_suid();
+
        if (!rc.config_dir) {
                rc.config_dir = config_dir();
        }

diff --git a/src/server.c b/src/server.c
index 7195d7d5e59ec24de703d5bbfa8d0ba7e5fa4300..f6a122494a35acccae803acae254a9ce0e17ec54 100644 (file)
--- a/src/server.c
+++ b/src/server.c
@@ -66,28 +66,6 @@ handle_sigterm(int signal, void *data)
        return 0;
 }
 
-static void
-drop_permissions(void)
-{
-       if (getuid() != geteuid() || getgid() != getegid()) {
-               wlr_log(WLR_ERROR, "!!! DEPRECATION WARNING: "
-                       "SUID privilege drop will be removed in future releases; "
-                       "Please migrate to seatd-launch");
-               if (setgid(getgid())) {
-                       wlr_log(WLR_ERROR, "unable to drop root group");
-                       exit(EXIT_FAILURE);
-               }
-               if (setuid(getuid())) {
-                       wlr_log(WLR_ERROR, "unable to drop root user");
-                       exit(EXIT_FAILURE);
-               }
-       }
-       if (setgid(0) != -1 || setuid(0) != -1) {
-               wlr_log(WLR_ERROR, "unable to drop root");
-               exit(EXIT_FAILURE);
-       }
-}
-
 static void
 seat_inhibit_input(struct seat *seat,  struct wl_client *active_client)
 {
@@ -217,16 +195,6 @@ server_init(struct server *server)
                exit(EXIT_FAILURE);
        }
 
-       /*
-        * The wlroots library makes use of systemd's logind to handle sessions
-        * and to allow compositors to run without elevated privileges.
-        * If running without logind or elogind, users may choose to set the
-        * setuid bit on the labwc executable despite associated security
-        * implications. In order to support this, but limit the elevated
-        * privileges as much as possible, we drop permissions at this point.
-        */
-       drop_permissions();
-
        /*
         * Autocreates a renderer, either Pixman, GLES2 or Vulkan for us. The
         * user can also specify a renderer using the WLR_RENDERER env var.