diff options
Diffstat (limited to 'networking')
| -rw-r--r-- | networking/telnetd.c | 34 |
1 files changed, 23 insertions, 11 deletions
diff --git a/networking/telnetd.c b/networking/telnetd.c index cccf03d..108bbf4 100644 --- a/networking/telnetd.c +++ b/networking/telnetd.c @@ -279,6 +279,10 @@ make_new_session( /* make new session and process group */ setsid(); + /* Restore default signal handling */ + signal(SIGCHLD, SIG_DFL); + signal(SIGPIPE, SIG_DFL); + /* open the child's side of the tty. */ /* NB: setsid() disconnects from any previous ctty's. Therefore * we must open child's side of the tty AFTER setsid! */ @@ -302,14 +306,18 @@ make_new_session( /* Uses FILE-based I/O to stdout, but does fflush(stdout), * so should be safe with vfork. * I fear, though, that some users will have ridiculously big - * issue files, and they may block writing to fd 1. */ + * issue files, and they may block writing to fd 1, + * (parent is supposed to read it, but parent waits + * for vforked child to exec!) */ print_login_issue(issuefile, NULL); /* Exec shell / login / whatever */ login_argv[0] = loginpath; login_argv[1] = NULL; - execvp(loginpath, (char **)login_argv); - /* Safer with vfork, and we shouldn't send message + /* exec busybox applet (if PREFER_APPLETS=y), if that fails, + * exec external program */ + BB_EXECVP(loginpath, (char **)login_argv); + /* _exit is safer with vfork, and we shouldn't send message * to remote clients anyway */ _exit(1); /*bb_perror_msg_and_die("execv %s", loginpath);*/ } @@ -374,7 +382,7 @@ free_session(struct tsession *ts) #else /* !FEATURE_TELNETD_STANDALONE */ -/* Used in main() only, thus exits. */ +/* Used in main() only, thus "return 0" actually is exit(0). */ #define free_session(ts) return 0 #endif @@ -384,20 +392,22 @@ static void handle_sigchld(int sig) pid_t pid; struct tsession *ts; - pid = waitpid(-1, &sig, WNOHANG); - if (pid > 0) { + /* Looping: more than one child may have exited */ + while (1) { + pid = waitpid(-1, NULL, WNOHANG); + if (pid <= 0) + break; ts = sessions; while (ts) { if (ts->shell_pid == pid) { ts->shell_pid = -1; - return; + break; } ts = ts->next; } } } - int telnetd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int telnetd_main(int argc, char **argv) { @@ -430,7 +440,7 @@ int telnetd_main(int argc, char **argv) if (!(opt & OPT_FOREGROUND)) { /* DAEMON_CHDIR_ROOT was giving inconsistent * behavior with/without -F, -i */ - bb_daemonize_or_rexec(0 /*DAEMON_CHDIR_ROOT*/, argv); + bb_daemonize_or_rexec(0 /*was DAEMON_CHDIR_ROOT*/, argv); } } /* Redirect log to syslog early, if needed */ @@ -466,6 +476,8 @@ int telnetd_main(int argc, char **argv) if (opt & OPT_WATCHCHILD) signal(SIGCHLD, handle_sigchld); + else /* prevent dead children from becoming zombies */ + signal(SIGCHLD, SIG_IGN); /* This is how the buffers are used. The arrows indicate the movement @@ -497,7 +509,7 @@ int telnetd_main(int argc, char **argv) while (ts) { struct tsession *next = ts->next; /* in case we free ts. */ if (ts->shell_pid == -1) { - /* Child died ad we detected that */ + /* Child died and we detected that */ free_session(ts); } else { if (ts->size1 > 0) /* can write to pty */ @@ -514,7 +526,7 @@ int telnetd_main(int argc, char **argv) if (!IS_INETD) { FD_SET(master_fd, &rdfdset); /* This is needed because free_session() does not - * take into account master_fd when it finds new + * take master_fd into account when it finds new * maxfd among remaining fd's */ if (master_fd > maxfd) maxfd = master_fd; |