ip netns: Reset vrf to default VRF on namespace switch

A vrf is local to a namespace. Drop any VRF association before trying
to exec a command in the new namespace.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>

ip/ip_common.h

@@ -58,6 +58,7 @@ int do_tcp_metrics(int argc, char **argv);
 int do_ipnetconf(int argc, char **argv);
 int do_iptoken(int argc, char **argv);
 int do_ipvrf(int argc, char **argv);
+void vrf_reset(void);
 
 int iplink_get(unsigned int flags, char *name, __u32 filt_mask);
 

ip/ipnetns.c

@@ -387,6 +387,11 @@ static int netns_exec(int argc, char **argv)
 	if (netns_switch(argv[0]))
 		return -1;
 
+	/* we just changed namespaces. clear any vrf association
+	 * with prior namespace before exec'ing command
+	 */
+	vrf_reset();
+
 	/* ip must return the status of the child,
 	 * but do_cmd() will add a minus to this,
 	 * so let's add another one here to cancel it.

ip/ipvrf.c

@@ -277,6 +277,20 @@ static int ipvrf_exec(int argc, char **argv)
 	return -cmd_exec(argv[1], argv + 1, !!batch_mode);
 }
 
+/* reset VRF association of current process to default VRF;
+ * used by netns_exec
+ */
+void vrf_reset(void)
+{
+	char vrf[32];
+
+	if (vrf_identify(getpid(), vrf, sizeof(vrf)) ||
+	    (vrf[0] == '\0'))
+		return;
+
+	vrf_switch("default");
+}
+
 int do_ipvrf(int argc, char **argv)
 {
 	if (argc == 0) {