treewide: Add SOCK_CLOEXEC to accept() calls that are missing it

Generally we try to set the O_CLOEXEC flag on every fd we create.  This
seems to be generally accepted security best practice these days, and we
never exec(), so certainly have no need to pass fds to exec()ed processes.

A handful of accept4() calls on Unix sockets are missing the SOCK_CLOEXEC
flag to set this though.  Add the missing flag.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

2 files changed, 5 insertions, 4 deletions

diff --git a/repair.c b/repair.c
index 69c5307..3e0e3e0 100644
--- a/repair.c
+++ b/repair.c
@@ -87,7 +87,7 @@ int repair_listen_handler(struct ctx *c, uint32_t events)
 	/* Another client is already connected: accept and close right away. */
 	if (c->fd_repair != -1) {
 		int discard = accept4(c->fd_repair_listen, NULL, NULL,
-				      SOCK_NONBLOCK);
+				      SOCK_NONBLOCK | SOCK_CLOEXEC);
 
 		if (discard == -1)
 			return errno;
@@ -99,7 +99,8 @@ int repair_listen_handler(struct ctx *c, uint32_t events)
 		return EEXIST;
 	}
 
-	if ((c->fd_repair = accept4(c->fd_repair_listen, NULL, NULL, 0)) < 0) {
+	if ((c->fd_repair = accept4(c->fd_repair_listen, NULL, NULL,
+				    SOCK_CLOEXEC)) < 0) {
 		rc = errno;
 		debug_perror("accept4() on TCP_REPAIR helper listening socket");
 		return rc;
diff --git a/tap.c b/tap.c
index bf0904f..e0d3ee5 100644
--- a/tap.c
+++ b/tap.c
@@ -1479,7 +1479,7 @@ void tap_listen_handler(struct ctx *c, uint32_t events)
 	/* Another client is already connected: accept and close right away. */
 	if (c->fd_tap != -1) {
 		int discard = accept4(c->fd_tap_listen, NULL, NULL,
-				      SOCK_NONBLOCK);
+				      SOCK_NONBLOCK | SOCK_CLOEXEC);
 
 		if (discard == -1)
 			return;
@@ -1492,7 +1492,7 @@ void tap_listen_handler(struct ctx *c, uint32_t events)
 		return;
 	}
 
-	c->fd_tap = accept4(c->fd_tap_listen, NULL, NULL, 0);
+	c->fd_tap = accept4(c->fd_tap_listen, NULL, NULL, SOCK_CLOEXEC);
 
 	if (!getsockopt(c->fd_tap, SOL_SOCKET, SO_PEERCRED, &ucred, &len))
 		info("accepted connection from PID %i", ucred.pid);