1 files changed, 40 insertions, 8 deletions

diff --git a/src/firejail/main.c b/src/firejail/main.c
index faa4972e2..61f507f36 100644
--- a/src/firejail/main.c
+++ b/src/firejail/main.c
@@ -157,12 +157,35 @@ static void myexit(int rv) {
         exit(rv);
 }
 
-static void my_handler(int s){
-        EUID_ROOT();
+static void my_handler(int s) {
         fmessage("\nParent received signal %d, shutting down the child process...\n", s);
         logsignal(s);
-        kill(child, SIGTERM);
-        myexit(1);
+        if (waitpid(child, NULL, WNOHANG) == 0) {
+                if (has_handler(child, s)) // signals are not delivered if there is no handler yet
+                        kill(child, s);
+                else
+                        kill(child, SIGKILL);
+                waitpid(child, NULL, 0);
+        }
+        myexit(s);
+}
+
+static void install_handler(void) {
+        struct sigaction sga;
+
+        // block SIGTERM while handling SIGINT
+        sigemptyset(&sga.sa_mask);
+        sigaddset(&sga.sa_mask, SIGTERM);
+        sga.sa_handler = my_handler;
+        sga.sa_flags = 0;
+        sigaction(SIGINT, &sga, NULL);
+
+        // block SIGINT while handling SIGTERM
+        sigemptyset(&sga.sa_mask);
+        sigaddset(&sga.sa_mask, SIGINT);
+        sga.sa_handler = my_handler;
+        sga.sa_flags = 0;
+        sigaction(SIGTERM, &sga, NULL);
 }
 
 // return 1 if error, 0 if a valid pid was found
@@ -2601,16 +2624,25 @@ int main(int argc, char **argv) {
                 flock(lockfd_network, LOCK_UN);
                 close(lockfd_network);
         }
+        EUID_USER();
+
+        int status = 0;
+        //*****************************
+        // following code is signal-safe
 
         // handle CTRL-C in parent
-        signal (SIGINT, my_handler);
-        signal (SIGTERM, my_handler);
+        install_handler();
 
         // wait for the child to finish
-        EUID_USER();
-        int status = 0;
         waitpid(child, &status, 0);
 
+        // restore default signal actions
+        signal(SIGTERM, SIG_DFL);
+        signal(SIGINT, SIG_DFL);
+
+        // end of signal-safe code
+        //*****************************
+
         // free globals
         if (cfg.profile) {
                 ProfileEntry *prf = cfg.profile;