Check if a control socket or address is already in use befor using it.

If it is used abort startup or let a reload fail.
Sockets are now not unlinked anymore on regular shutdown.

This helps a lot when one tries to do a config check without -n.

Inputs and OK claudio@

5 files changed, 53 insertions, 24 deletions

diff --git a/usr.sbin/bgpd/bgpd.c b/usr.sbin/bgpd/bgpd.c
index 0c4fad69c0d..711551e5cdc 100644
--- a/usr.sbin/bgpd/bgpd.c
+++ b/usr.sbin/bgpd/bgpd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bgpd.c,v 1.204 2018/09/29 08:11:11 claudio Exp $ */
+/*	$OpenBSD: bgpd.c,v 1.205 2018/12/27 20:23:24 remi Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -348,8 +348,6 @@ BROKEN	if (pledge("stdio rpath wpath cpath fattr unix route recvfd sendfd",
 		free(p);
 	}
 
-	control_cleanup(conf->csock);
-	control_cleanup(conf->rcsock);
 	carp_demote_shutdown();
 	kr_shutdown(conf->fib_priority, conf->default_tableid);
 	pftable_clear_all();
@@ -453,10 +451,20 @@ reconfigure(char *conffile, struct bgpd_config *conf, struct peer **peer_l)
 		reconfpending = 0;
 		return (1);
 	}
+
+	if (prepare_listeners(conf) == -1) {
+		reconfpending = 0;
+		return (1);
+	}
+
+	if (control_setup(conf) == -1) {
+		reconfpending = 0;
+		return (1);
+	}
+
 	expand_networks(conf);
 
 	cflags = conf->flags;
-	prepare_listeners(conf);
 
 	/* start reconfiguration */
 	if (imsg_compose(ibuf_se, IMSG_RECONF_CONF, 0, 0, -1,
@@ -473,9 +481,6 @@ reconfigure(char *conffile, struct bgpd_config *conf, struct peer **peer_l)
 		la->fd = -1;
 	}
 
-	if (control_setup(conf) == -1)
-		return (-1);
-
 	/* adjust fib syncing on reload */
 	ktable_preload();
 
@@ -934,11 +939,12 @@ control_setup(struct bgpd_config *conf)
 	/* control socket is outside chroot */
 	if (!cname || strcmp(cname, conf->csock)) {
 		if (cname) {
-			control_cleanup(cname);
 			free(cname);
 		}
 		if ((cname = strdup(conf->csock)) == NULL)
 			fatal("strdup");
+		if (control_check(cname) == -1)
+			return (-1);
 		if ((fd = control_init(0, cname)) == -1)
 			fatalx("control socket setup failed");
 		if (control_listen(fd) == -1)
@@ -950,16 +956,16 @@ control_setup(struct bgpd_config *conf)
 	}
 	if (!conf->rcsock) {
 		/* remove restricted socket */
-		control_cleanup(rcname);
 		free(rcname);
 		rcname = NULL;
 	} else if (!rcname || strcmp(rcname, conf->rcsock)) {
 		if (rcname) {
-			control_cleanup(rcname);
 			free(rcname);
 		}
 		if ((rcname = strdup(conf->rcsock)) == NULL)
 			fatal("strdup");
+		if (control_check(rcname) == -1)
+			return (-1);
 		if ((fd = control_init(1, rcname)) == -1)
 			fatalx("control socket setup failed");
 		if (control_listen(fd) == -1)
diff --git a/usr.sbin/bgpd/bgpd.h b/usr.sbin/bgpd/bgpd.h
index 7f981155023..322fb047d25 100644
--- a/usr.sbin/bgpd/bgpd.h
+++ b/usr.sbin/bgpd/bgpd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bgpd.h,v 1.359 2018/12/22 16:12:40 claudio Exp $ */
+/*	$OpenBSD: bgpd.h,v 1.360 2018/12/27 20:23:24 remi Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -1127,7 +1127,6 @@ void		 set_pollfd(struct pollfd *, struct imsgbuf *);
 int		 handle_pollfd(struct pollfd *, struct imsgbuf *);
 
 /* control.c */
-void	control_cleanup(const char *);
 int	control_imsg_relay(struct imsg *);
 
 /* config.c */
diff --git a/usr.sbin/bgpd/config.c b/usr.sbin/bgpd/config.c
index 6cc77d2d1c6..d0546dfaebe 100644
--- a/usr.sbin/bgpd/config.c
+++ b/usr.sbin/bgpd/config.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: config.c,v 1.78 2018/11/14 17:24:01 mestre Exp $ */
+/*	$OpenBSD: config.c,v 1.79 2018/12/27 20:23:24 remi Exp $ */
 
 /*
  * Copyright (c) 2003, 2004, 2005 Henning Brauer <henning@openbsd.org>
@@ -384,11 +384,12 @@ host_ip(const char *s, struct bgpd_addr *h, u_int8_t *len)
 	return (1);
 }
 
-void
+int
 prepare_listeners(struct bgpd_config *conf)
 {
 	struct listen_addr	*la, *next;
 	int			 opt = 1;
+	int			 r = 0;
 
 	if (TAILQ_EMPTY(conf->listen_addrs)) {
 		if ((la = calloc(1, sizeof(struct listen_addr))) == NULL)
@@ -459,9 +460,12 @@ prepare_listeners(struct bgpd_config *conf)
 			close(la->fd);
 			TAILQ_REMOVE(conf->listen_addrs, la, entry);
 			free(la);
+			r = -1;
 			continue;
 		}
 	}
+
+	return (r);
 }
 
 int
diff --git a/usr.sbin/bgpd/control.c b/usr.sbin/bgpd/control.c
index 0e2b1813eb8..1239b5e811f 100644
--- a/usr.sbin/bgpd/control.c
+++ b/usr.sbin/bgpd/control.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: control.c,v 1.92 2018/12/22 16:12:40 claudio Exp $ */
+/*	$OpenBSD: control.c,v 1.93 2018/12/27 20:23:24 remi Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -38,6 +38,32 @@ void		 control_result(struct ctl_conn *, u_int);
 ssize_t		 imsg_read_nofd(struct imsgbuf *);
 
 int
+control_check(char *path)
+{
+	struct sockaddr_un	 sun;
+	int			 fd;
+
+	bzero(&sun, sizeof(sun));
+	sun.sun_family = AF_UNIX;
+	strlcpy(sun.sun_path, path, sizeof(sun.sun_path));
+
+	if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
+		log_warn("%s: socket", __func__);
+		return (-1);
+	}
+
+	if (connect(fd, (struct sockaddr *)&sun, sizeof(sun)) == 0) {
+		log_warnx("control socket %s already in use", path);
+		close(fd);
+		return (-1);
+	}
+
+	close(fd);
+
+	return (0);
+}
+
+int
 control_init(int restricted, char *path)
 {
 	struct sockaddr_un	 sun;
@@ -110,13 +136,6 @@ control_shutdown(int fd)
 	close(fd);
 }
 
-void
-control_cleanup(const char *path)
-{
-	if (path)
-		unlink(path);
-}
-
 unsigned int
 control_accept(int listenfd, int restricted)
 {
diff --git a/usr.sbin/bgpd/session.h b/usr.sbin/bgpd/session.h
index 1c87025d7ef..5a90f294236 100644
--- a/usr.sbin/bgpd/session.h
+++ b/usr.sbin/bgpd/session.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: session.h,v 1.126 2018/12/22 16:12:40 claudio Exp $ */
+/*	$OpenBSD: session.h,v 1.127 2018/12/27 20:23:24 remi Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -247,10 +247,11 @@ int	 carp_demote_set(char *, int);
 /* config.c */
 int	 merge_config(struct bgpd_config *, struct bgpd_config *,
 	    struct peer *);
-void	 prepare_listeners(struct bgpd_config *);
+int	 prepare_listeners(struct bgpd_config *);
 int	 get_mpe_label(struct rdomain *);
 
 /* control.c */
+int	control_check(char *);
 int	control_init(int, char *);
 int	control_listen(int);
 void	control_shutdown(int);