fix x11 display reporting in firemon and firetools for sessions joining an existing x11 sandbox

3 files changed, 7 insertions, 2 deletions

diff --git a/src/firejail/firejail.h b/src/firejail/firejail.h
index b31d1365c..690f76e05 100644
--- a/src/firejail/firejail.h
+++ b/src/firejail/firejail.h
@@ -376,6 +376,7 @@ extern char *fullargv[MAX_ARGS];
 extern int fullargc;
 
 // main.c
+void set_x11_file(pid_t pid, int display);
 void check_user_namespace(void);
 char *guess_shell(void);
 
diff --git a/src/firejail/join.c b/src/firejail/join.c
index dd7b2e9bb..14e3ae920 100644
--- a/src/firejail/join.c
+++ b/src/firejail/join.c
@@ -61,6 +61,11 @@ static void extract_x11_display(pid_t pid) {
                 fprintf(stderr, "Error: invalid X11 display range\n");
                 return;
         }
+
+        // store the display number for join process in /run/firejail/x11
+        EUID_ROOT();
+        set_x11_file(getpid(), display);
+        EUID_USER();
 }
 
 static void extract_command(int argc, char **argv, int index) {
diff --git a/src/firejail/main.c b/src/firejail/main.c
index 9726c0b8a..71a37beb7 100644
--- a/src/firejail/main.c
+++ b/src/firejail/main.c
@@ -129,7 +129,6 @@ unsigned long long start_timestamp;
 
 static void set_name_file(pid_t pid);
 static void delete_name_file(pid_t pid);
-static void set_x11_file(pid_t pid, int display);
 static void delete_x11_file(pid_t pid);
 
 void clear_run_files(pid_t pid) {
@@ -738,7 +737,7 @@ static void delete_name_file(pid_t pid) {
         free(fname);
 }
 
-static void set_x11_file(pid_t pid, int display) {
+void set_x11_file(pid_t pid, int display) {
         char *fname;
         if (asprintf(&fname, "%s/%d", RUN_FIREJAIL_X11_DIR, pid) == -1)
                 errExit("asprintf");