ip, neigh: Add NTF_EXT_MANAGED support

Currently, ip neigh does not support the NTF_EXT_MANAGED flag. Add cmdline
support.

Usage example:

  # ./ip/ip n replace 192.168.178.30 dev enp5s0 managed extern_learn
  # ./ip/ip n
  192.168.178.30 dev enp5s0 lladdr f4:8c:50:5e:71:9a managed extern_learn REACHABLE
  [...]

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David Ahern <dsahern@kernel.org>

ip/ipneigh.c

@@ -51,7 +51,8 @@ static void usage(void)
 	fprintf(stderr,
 		"Usage: ip neigh { add | del | change | replace }\n"
 		"                { ADDR [ lladdr LLADDR ] [ nud STATE ] proxy ADDR }\n"
-		"                [ dev DEV ] [ router ] [ use ] [ extern_learn ] [ protocol PROTO ]\n"
+		"                [ dev DEV ] [ router ] [ use ] [ managed ] [ extern_learn ]\n"
+		"                [ protocol PROTO ]\n"
 		"\n"
 		"	ip neigh { show | flush } [ proxy ] [ to PREFIX ] [ dev DEV ] [ nud STATE ]\n"
 		"				  [ vrf NAME ] [ nomaster ]\n"
@@ -115,6 +116,7 @@ static int ipneigh_modify(int cmd, int flags, int argc, char **argv)
 		.ndm.ndm_family = preferred_family,
 		.ndm.ndm_state = NUD_PERMANENT,
 	};
+	__u32 ext_flags = 0;
 	char  *dev = NULL;
 	int dst_ok = 0;
 	int dev_ok = 0;
@@ -150,6 +152,9 @@ static int ipneigh_modify(int cmd, int flags, int argc, char **argv)
 			req.ndm.ndm_flags |= NTF_ROUTER;
 		} else if (strcmp(*argv, "use") == 0) {
 			req.ndm.ndm_flags |= NTF_USE;
+		} else if (strcmp(*argv, "managed") == 0) {
+			ext_flags |= NTF_EXT_MANAGED;
+			req.ndm.ndm_state = NUD_NONE;
 		} else if (matches(*argv, "extern_learn") == 0) {
 			req.ndm.ndm_flags |= NTF_EXT_LEARNED;
 		} else if (strcmp(*argv, "dev") == 0) {
@@ -185,7 +190,10 @@ static int ipneigh_modify(int cmd, int flags, int argc, char **argv)
 	req.ndm.ndm_family = dst.family;
 	if (addattr_l(&req.n, sizeof(req), NDA_DST, &dst.data, dst.bytelen) < 0)
 		return -1;
-
+	if (ext_flags &&
+	    addattr_l(&req.n, sizeof(req), NDA_FLAGS_EXT, &ext_flags,
+		      sizeof(ext_flags)) < 0)
+		return -1;
 	if (lla && strcmp(lla, "null")) {
 		char llabuf[20];
 		int l;
@@ -305,6 +313,7 @@ int print_neigh(struct nlmsghdr *n, void *arg)
 	int len = n->nlmsg_len;
 	struct rtattr *tb[NDA_MAX+1];
 	static int logit = 1;
+	__u32 ext_flags = 0;
 	__u8 protocol = 0;
 
 	if (n->nlmsg_type != RTM_NEWNEIGH && n->nlmsg_type != RTM_DELNEIGH &&
@@ -348,6 +357,8 @@ int print_neigh(struct nlmsghdr *n, void *arg)
 
 	if (tb[NDA_PROTOCOL])
 		protocol = rta_getattr_u8(tb[NDA_PROTOCOL]);
+	if (tb[NDA_FLAGS_EXT])
+		ext_flags = rta_getattr_u32(tb[NDA_FLAGS_EXT]);
 
 	if (filter.protocol && filter.protocol != protocol)
 		return 0;
@@ -430,13 +441,12 @@ int print_neigh(struct nlmsghdr *n, void *arg)
 
 	if (r->ndm_flags & NTF_ROUTER)
 		print_null(PRINT_ANY, "router", "%s ", "router");
-
 	if (r->ndm_flags & NTF_PROXY)
 		print_null(PRINT_ANY, "proxy", "%s ", "proxy");
-
+	if (ext_flags & NTF_EXT_MANAGED)
+		print_null(PRINT_ANY, "managed", "%s ", "managed");
 	if (r->ndm_flags & NTF_EXT_LEARNED)
 		print_null(PRINT_ANY, "extern_learn", "%s ", "extern_learn");
-
 	if (r->ndm_flags & NTF_OFFLOADED)
 		print_null(PRINT_ANY, "offload", "%s ", "offload");
 

man/man8/ip-neighbour.8

@@ -26,6 +26,7 @@ ip-neighbour \- neighbour/arp tables management.
 .IR DEV " ] [ "
 .BR router " ] [ "
 .BR use " ] [ "
+.BR managed " ] [ "
 .BR extern_learn " ]"
 
 .ti -8
@@ -100,6 +101,14 @@ the kernel that a controller is using this dynamic entry. If the entry
 does not exist, the kernel will resolve it. If it exists, an attempt
 to refresh the neighbor entry will be triggered.
 
+.TP
+.BI managed
+this neigh entry is "managed". This option can be used to indicate to
+the kernel that a controller is using this dynamic entry. In contrast
+to "use", if the entry does not exist, the kernel will resolve it and
+periodically attempt to auto-refresh the neighbor entry such that it
+remains in resolved state when possible.
+
 .TP
 .BI extern_learn
 this neigh entry was learned externally. This option can be used to