conf: Terminate on EMFILE or ENFILE on sockets for port mapping

In general, we don't terminate or report failures if we fail to bind
to some ports out of a given port range specifier, to allow users to
conveniently specify big port ranges (or "all") without having to
care about ports that might already be in use.

However, running out of the open file descriptors quota is a
different story: we can't do what the user requested in a very
substantial way.

For example, if the user specifies '-t all' and we can only bind
1024 sockets, the behaviour is rather unexpected.

Fail whenever socket creation returns -ENFILE or -EMFILE.

Link: https://bugs.passt.top/show_bug.cgi?id=27
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 29 insertions, 7 deletions

diff --git a/conf.c b/conf.c
index 05a8674..ce60432 100644
--- a/conf.c
+++ b/conf.c
@@ -184,6 +184,7 @@ static void conf_ports(const struct ctx *c, char optname, const char *optarg,
 	bool exclude_only = true, bound_one = false;
 	uint8_t exclude[PORT_BITMAP_SIZE] = { 0 };
 	sa_family_t af = AF_UNSPEC;
+	int ret;
 
 	if (!strcmp(optarg, "none")) {
 		if (fwd->mode)
@@ -218,11 +219,18 @@ static void conf_ports(const struct ctx *c, char optname, const char *optarg,
 
 		for (i = 0; i < PORT_EPHEMERAL_MIN; i++) {
 			if (optname == 't') {
-				if (!tcp_sock_init(c, AF_UNSPEC, NULL, NULL, i))
+				ret = tcp_sock_init(c, AF_UNSPEC, NULL, NULL,
+						    i);
+				if (ret == -ENFILE || ret == -EMFILE)
+					goto enfile;
+				if (!ret)
 					bound_one = true;
 			} else if (optname == 'u') {
-				if (!udp_sock_init(c, 0, AF_UNSPEC, NULL, NULL,
-						   i))
+				ret = udp_sock_init(c, 0, AF_UNSPEC, NULL, NULL,
+						    i);
+				if (ret == -ENFILE || ret == -EMFILE)
+					goto enfile;
+				if (!ret)
 					bound_one = true;
 			}
 		}
@@ -303,10 +311,16 @@ static void conf_ports(const struct ctx *c, char optname, const char *optarg,
 			bitmap_set(fwd->map, i);
 
 			if (optname == 't') {
-				if (!tcp_sock_init(c, af, addr, ifname, i))
+				ret = tcp_sock_init(c, af, addr, ifname, i);
+				if (ret == -ENFILE || ret == -EMFILE)
+					goto enfile;
+				if (!ret)
 					bound_one = true;
 			} else if (optname == 'u') {
-				if (!udp_sock_init(c, 0, af, addr, ifname, i))
+				ret = udp_sock_init(c, 0, af, addr, ifname, i);
+				if (ret == -ENFILE || ret == -EMFILE)
+					goto enfile;
+				if (!ret)
 					bound_one = true;
 			} else {
 				/* No way to check in advance for -T and -U */
@@ -358,10 +372,16 @@ static void conf_ports(const struct ctx *c, char optname, const char *optarg,
 			fwd->delta[i] = mapped_range.first - orig_range.first;
 
 			if (optname == 't') {
-				if (!tcp_sock_init(c, af, addr, ifname, i))
+				ret = tcp_sock_init(c, af, addr, ifname, i);
+				if (ret == -ENFILE || ret == -EMFILE)
+					goto enfile;
+				if (!ret)
 					bound_one = true;
 			} else if (optname == 'u') {
-				if (!udp_sock_init(c, 0, af, addr, ifname, i))
+				ret = udp_sock_init(c, 0, af, addr, ifname, i);
+				if (ret == -ENFILE || ret == -EMFILE)
+					goto enfile;
+				if (!ret)
 					bound_one = true;
 			} else {
 				/* No way to check in advance for -T and -U */
@@ -374,6 +394,8 @@ static void conf_ports(const struct ctx *c, char optname, const char *optarg,
 		goto bind_fail;
 
 	return;
+enfile:
+	die("Can't open enough sockets for port specifier: %s", optarg);
 bad:
 	die("Invalid port specifier %s", optarg);
 overlap: