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Description: Improve security in daemonised execution.
Ignore signals irrelevant to a long living daemon
which was crafted with orderly shutdown.
.
Replace standard file descriptors with a tie to "/dev/null".
.
Yield controlling terminal properly by seting session ID.
Author: Mats Erik Andersson <debian@gisladisker.se>
Forwarded: no
Last-Update: 2011-03-08
Index: tcpspy-1.7d/tcpspy.c
===================================================================
--- tcpspy-1.7d.orig/tcpspy.c
+++ tcpspy-1.7d/tcpspy.c
@@ -54,8 +54,10 @@
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
+#include <sys/stat.h> /* umask() */
+#include <fcntl.h> /* open /dev/null */
#include <unistd.h>
-
+#include <paths.h> /* _PATH_DEVNULL */
#include "log.h"
#include "rcsid.h"
#include "rule.h"
@@ -656,6 +658,15 @@ int main (int argc, char *argv[])
if (debug == 0) {
pid_t p;
+ int nullfd;
+
+ /* Hinder early disturbance generated by terminal. */
+ signal (SIGHUP, SIG_IGN);
+ signal (SIGINT, SIG_IGN);
+ signal (SIGQUIT, SIG_IGN);
+ signal (SIGTSTP, SIG_IGN);
+ signal (SIGUSR1, SIG_IGN);
+ signal (SIGUSR2, SIG_IGN);
/* 1st fork */
p = fork();
@@ -666,6 +677,13 @@ int main (int argc, char *argv[])
} else if (p != 0)
exit (0);
+ /* Give up controlling terminal */
+ if (setsid () < 0) {
+ fprintf (stderr, "tcpspy: setsid: %s\n",
+ strerror (errno));
+ exit (EXIT_FAILURE);
+ }
+
/* 2nd fork */
p = fork();
if (p < 0) {
@@ -679,11 +697,22 @@ int main (int argc, char *argv[])
}
ioctl (STDIN_FILENO, TIOCNOTTY, NULL);
- close (STDIN_FILENO);
- close (STDOUT_FILENO);
- close (STDERR_FILENO);
+
+ nullfd = open (_PATH_DEVNULL, O_RDWR, 0);
+ if (nullfd < 0) {
+ fprintf (stderr, "tcpspy: cannot open %s\n",
+ _PATH_DEVNULL);
+ exit (EXIT_FAILURE);
+ }
+
+ dup2 (nullfd, STDIN_FILENO);
+ dup2 (nullfd, STDOUT_FILENO);
+ dup2 (nullfd, STDERR_FILENO);
+ close (nullfd);
+
setpgid (0, 0);
chdir ("/");
+ umask (0);
} else
fprintf (stderr, "tcpspy 1.7d started (debug)\n");
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