When syslogd received a SIGHUP during startup, it died instead of

reloading its config.  This could happen when multiple signals were
sent during a short interval.  So block SIGHUP until signal handlers
are installed.
OK deraadt@ jca@

2 files changed, 22 insertions, 2 deletions

diff --git a/usr.sbin/syslogd/privsep.c b/usr.sbin/syslogd/privsep.c
index 2733c48c0da..643b2a4a038 100644
--- a/usr.sbin/syslogd/privsep.c
+++ b/usr.sbin/syslogd/privsep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: privsep.c,v 1.65 2016/12/27 19:16:24 bluhm Exp $	*/
+/*	$OpenBSD: privsep.c,v 1.66 2016/12/30 23:21:26 bluhm Exp $	*/
 
 /*
  * Copyright (c) 2003 Anil Madhavapeddy <anil@recoil.org>
@@ -175,6 +175,7 @@ priv_exec(char *conf, int numeric, int child, int argc, char *argv[])
 	struct stat cf_info, cf_stat;
 	struct addrinfo hints, *res0;
 	struct sigaction sa;
+	sigset_t sigmask;
 
 	if (pledge("stdio rpath wpath cpath dns getpw sendfd id proc exec",
 	    NULL) == -1)
@@ -209,6 +210,10 @@ priv_exec(char *conf, int numeric, int child, int argc, char *argv[])
 	setproctitle("[priv]");
 	logdebug("[priv]: fork+exec done\n");
 
+	sigemptyset(&sigmask);
+	if (sigprocmask(SIG_SETMASK, &sigmask, NULL) == -1)
+		err(1, "sigprocmask priv");
+
 	if (stat(conf, &cf_info) < 0)
 		err(1, "stat config file failed");
 
@@ -409,6 +414,10 @@ priv_exec(char *conf, int numeric, int child, int argc, char *argv[])
 		int status;
 
 		waitpid(child_pid, &status, 0);
+		sigemptyset(&sigmask);
+		sigaddset(&sigmask, SIGHUP);
+		if (sigprocmask(SIG_SETMASK, &sigmask, NULL) == -1)
+			err(1, "sigprocmask exec");
 		execvp(argv[0], argv);
 		err(1, "exec restart '%s' failed", argv[0]);
 	}
diff --git a/usr.sbin/syslogd/syslogd.c b/usr.sbin/syslogd/syslogd.c
index a2fb57f451f..878a35a86cd 100644
--- a/usr.sbin/syslogd/syslogd.c
+++ b/usr.sbin/syslogd/syslogd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: syslogd.c,v 1.225 2016/12/27 19:16:24 bluhm Exp $	*/
+/*	$OpenBSD: syslogd.c,v 1.226 2016/12/30 23:21:26 bluhm Exp $	*/
 
 /*
  * Copyright (c) 1983, 1988, 1993, 1994
@@ -354,6 +354,7 @@ main(int argc, char *argv[])
 	struct event	*ev_klog, *ev_sendsys, *ev_udp, *ev_udp6,
 			*ev_bind, *ev_listen, *ev_tls, *ev_unix,
 			*ev_hup, *ev_int, *ev_quit, *ev_term, *ev_mark;
+	sigset_t	 sigmask;
 	const char	*errstr;
 	char		*p;
 	int		 ch, i;
@@ -361,6 +362,12 @@ main(int argc, char *argv[])
 	int		 fd_ctlsock, fd_klog, fd_sendsys, fd_bind, fd_listen;
 	int		*fd_unix;
 
+	/* block signal until handler is set up */
+	sigemptyset(&sigmask);
+	sigaddset(&sigmask, SIGHUP);
+	if (sigprocmask(SIG_SETMASK, &sigmask, NULL) == -1)
+		err(1, "sigprocmask block");
+
 	if ((path_unix = malloc(sizeof(*path_unix))) == NULL)
 		err(1, "malloc %s", _PATH_LOG);
 	path_unix[0] = _PATH_LOG;
@@ -840,6 +847,10 @@ main(int argc, char *argv[])
 	logmsg(LOG_SYSLOG|LOG_INFO, "syslogd: start", LocalHostName, ADDDATE);
 	logdebug("syslogd: started\n");
 
+	sigemptyset(&sigmask);
+	if (sigprocmask(SIG_SETMASK, &sigmask, NULL) == -1)
+		err(1, "sigprocmask unblock");
+
 	event_dispatch();
 	/* NOTREACHED */
 	return (0);