Package: tcpspy Version: 1.7d-4 Severity: wishlist Tags: patch Tcpspy is clearly intended to be a long living daemon. As such it is reacting on an alarmingly large number of signals. One could also argue that it would benefit slightly from a stricter handling of file descriptors, more in line with security measures for other daemons. I contribute one mode of implementing these changes.
Best regards, Mats Erik Andersson, DM
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 <[email protected]> Forwarded: no Last-Update: 2011-03-08 --- tcpspy-1.7d.debian/tcpspy.c 2002-01-25 02:01:02.000000000 +0100 +++ tcpspy-1.7d/tcpspy.c 2011-03-08 20:56:37.000000000 +0100 @@ -53,7 +53,10 @@ #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" @@ -607,7 +610,16 @@ 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(); if (p < 0) { @@ -617,6 +629,13 @@ } 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) { @@ -630,11 +649,22 @@ } 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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