netdev - [PATCH iproute2-next 10/12] ip bridge: Set NETLINK_DUMP_STRICT

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Date:   Wed, 19 Dec 2018 19:54:25 -0800
From:   David Ahern <dsahern@...nel.org>
To:     netdev@...r.kernel.org
Cc:     stephen@...workplumber.org, David Ahern <dsahern@...il.com>
Subject: [PATCH iproute2-next 10/12] ip bridge: Set NETLINK_DUMP_STRICT_CHK on socket

From: David Ahern <dsahern@...il.com>

iproute2 has been updated for the new strict policy in the kernel. Add a
helper to call setsockopt to enable the feature. Add a call to ip.c and
bridge.c

The setsockopt fails on older kernels and the error can be safely ignored
- any new fields or attributes are ignored by the older kernel.

Signed-off-by: David Ahern <dsahern@...il.com>
---
 bridge/bridge.c      | 4 ++++
 include/libnetlink.h | 1 +
 ip/ip.c              | 2 ++
 lib/libnetlink.c     | 9 +++++++++
 4 files changed, 16 insertions(+)

diff --git a/bridge/bridge.c b/bridge/bridge.c
index a3d8154be898..a50d9d59b4c5 100644
--- a/bridge/bridge.c
+++ b/bridge/bridge.c
@@ -97,6 +97,8 @@ static int batch(const char *name)
 		return EXIT_FAILURE;
 	}
 
+	rtnl_set_strict_dump(&rth);
+
 	cmdlineno = 0;
 	while (getcmdline(&line, &len, stdin) != -1) {
 		char *largv[100];
@@ -205,6 +207,8 @@ main(int argc, char **argv)
 	if (rtnl_open(&rth, 0) < 0)
 		exit(1);
 
+	rtnl_set_strict_dump(&rth);
+
 	if (argc > 1)
 		return do_cmd(argv[1], argc-1, argv+1);
 
diff --git a/include/libnetlink.h b/include/libnetlink.h
index 2621bc99ce7b..dc0c9c4eb3f5 100644
--- a/include/libnetlink.h
+++ b/include/libnetlink.h
@@ -46,6 +46,7 @@ int rtnl_open_byproto(struct rtnl_handle *rth, unsigned int subscriptions,
 	__attribute__((warn_unused_result));
 
 void rtnl_close(struct rtnl_handle *rth);
+void rtnl_set_strict_dump(struct rtnl_handle *rth);
 
 typedef int (*req_filter_fn_t)(struct nlmsghdr *nlh, int reqlen);
 
diff --git a/ip/ip.c b/ip/ip.c
index a5bbacb4bb0f..e4131714018f 100644
--- a/ip/ip.c
+++ b/ip/ip.c
@@ -308,6 +308,8 @@ int main(int argc, char **argv)
 	if (rtnl_open(&rth, 0) < 0)
 		exit(1);
 
+	rtnl_set_strict_dump(&rth);
+
 	if (strlen(basename) > 2)
 		return do_cmd(basename+2, argc, argv);
 
diff --git a/lib/libnetlink.c b/lib/libnetlink.c
index 0ddd646a8775..7b02c754c1d0 100644
--- a/lib/libnetlink.c
+++ b/lib/libnetlink.c
@@ -161,6 +161,15 @@ static int nl_dump_ext_ack_done(const struct nlmsghdr *nlh, int error)
 }
 #endif
 
+/* Older kernels may not support strict dump and filtering */
+void rtnl_set_strict_dump(struct rtnl_handle *rth)
+{
+	int one = 1;
+
+	setsockopt(rth->fd, SOL_NETLINK, NETLINK_DUMP_STRICT_CHK,
+		   &one, sizeof(one));
+}
+
 void rtnl_close(struct rtnl_handle *rth)
 {
 	if (rth->fd >= 0) {
-- 
2.11.0