1 files changed, 33 insertions, 10 deletions

diff --git a/sway/main.c b/sway/main.c
index b9549b12..82375e0b 100644
--- a/sway/main.c
+++ b/sway/main.c
@@ -1,4 +1,4 @@
-#define _XOPEN_SOURCE 500
+#define _XOPEN_SOURCE 700
 #define _POSIX_C_SOURCE 200112L
 #include <stdio.h>
 #include <stdlib.h>
@@ -27,6 +27,7 @@
 #include "stringop.h"
 #include "sway.h"
 #include "log.h"
+#include "util.h"
 
 static bool terminate_request = false;
 static int exit_value = 0;
@@ -209,6 +210,27 @@ static void security_sanity_check() {
 #endif
 }
 
+static void executable_sanity_check() {
+#ifdef __linux__
+                struct stat sb;
+                char *exe = realpath("/proc/self/exe", NULL);
+                stat(exe, &sb);
+                // We assume that cap_get_file returning NULL implies ENODATA
+                if (sb.st_mode & (S_ISUID|S_ISGID) && cap_get_file(exe)) {
+                        sway_log(L_ERROR,
+                                "sway executable has both the s(g)uid bit AND file caps set.");
+                        sway_log(L_ERROR,
+                                "This is strongly discouraged (and completely broken).");
+                        sway_log(L_ERROR,
+                                "Please clear one of them (either the suid bit, or the file caps).");
+                        sway_log(L_ERROR,
+                                "If unsure, strip the file caps.");
+                        exit(EXIT_FAILURE);
+                }
+                free(exe);
+#endif
+}
+
 int main(int argc, char **argv) {
         static int verbose = 0, debug = 0, validate = 0;
 
@@ -288,6 +310,15 @@ int main(int argc, char **argv) {
                 }
         }
 
+        // we need to setup logging before wlc_init in case it fails.
+        if (debug) {
+                init_log(L_DEBUG);
+        } else if (verbose || validate) {
+                init_log(L_INFO);
+        } else {
+                init_log(L_ERROR);
+        }
+
         if (optind < argc) { // Behave as IPC client
                 if(optind != 1) {
                         sway_log(L_ERROR, "Don't use options with the IPC client");
@@ -317,6 +348,7 @@ int main(int argc, char **argv) {
                 return 0;
         }
 
+        executable_sanity_check();
 #ifdef __linux__
         bool suid = false;
         if (getuid() != geteuid() || getgid() != getegid()) {
@@ -329,14 +361,6 @@ int main(int argc, char **argv) {
         }
 #endif
 
-        // we need to setup logging before wlc_init in case it fails.
-        if (debug) {
-                init_log(L_DEBUG);
-        } else if (verbose || validate) {
-                init_log(L_INFO);
-        } else {
-                init_log(L_ERROR);
-        }
         wlc_log_set_handler(wlc_log_handler);
         log_kernel();
         log_distro();
@@ -409,4 +433,3 @@ int main(int argc, char **argv) {
 
         return exit_value;
 }
-