From: Ido Schimmel <idosch@nvidia.com>
Date: Tue, 1 Jul 2025 14:42:16 +0000 (+0300)
Subject: ip neigh: Add support for "extern_valid" flag
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1ac42adcb600bbbbe94ee43a4fcc8f3061817600;p=thirdparty%2Fiproute2.git

ip neigh: Add support for "extern_valid" flag

Add support for the recently added "extern_valid" flag that can be used
to indicate to the kernel that a neighbor entry was learned and
determined to be valid externally. The kernel will not remove or
invalidate the entry, but it can probe the entry and notify user space
when the entry becomes reachable. The kernel will return the entry to
stale state if it did not receive a confirmation after probing the
entry.

Example usage and output:

 # ip neigh add 192.0.2.1 nud none dev br0.10 extern_valid
 Error: Cannot create externally validated neighbor with an invalid state.
 # ip neigh add 192.0.2.1 lladdr 00:11:22:33:44:55 nud stale dev br0.10 extern_valid
 $ ip neigh show dev br0.10
 192.0.2.1 lladdr 00:11:22:33:44:55 extern_valid STALE
 $ ip -j -p neigh show dev br0.10
 [ {
         "dst": "192.0.2.1",
         "lladdr": "00:11:22:33:44:55",
         "extern_valid": null,
         "state": [ "STALE" ]
     } ]

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David Ahern <dsahern@kernel.org>
---

diff --git a/ip/ipneigh.c b/ip/ipneigh.c
index bd7f44e1..e678545a 100644
--- a/ip/ipneigh.c
+++ b/ip/ipneigh.c
@@ -47,7 +47,7 @@ static void usage(void)
 		"Usage: ip neigh { add | del | change | replace }\n"
 		"                { ADDR [ lladdr LLADDR ] [ nud STATE ] proxy ADDR }\n"
 		"                [ dev DEV ] [ router ] [ use ] [ managed ] [ extern_learn ]\n"
-		"                [ protocol PROTO ]\n"
+		"                [ extern_valid ] [ protocol PROTO ]\n"
 		"\n"
 		"	ip neigh { show | flush } [ proxy ] [ to PREFIX ] [ dev DEV ] [ nud STATE ]\n"
 		"				  [ vrf NAME ] [ nomaster ]\n"
@@ -152,6 +152,8 @@ static int ipneigh_modify(int cmd, int flags, int argc, char **argv)
 			req.ndm.ndm_state = NUD_NONE;
 		} else if (matches(*argv, "extern_learn") == 0) {
 			req.ndm.ndm_flags |= NTF_EXT_LEARNED;
+		} else if (strcmp(*argv, "extern_valid") == 0) {
+			ext_flags |= NTF_EXT_EXT_VALIDATED;
 		} else if (strcmp(*argv, "dev") == 0) {
 			NEXT_ARG();
 			dev = *argv;
@@ -446,6 +448,8 @@ int print_neigh(struct nlmsghdr *n, void *arg)
 		print_null(PRINT_ANY, "extern_learn", "%s ", "extern_learn");
 	if (r->ndm_flags & NTF_OFFLOADED)
 		print_null(PRINT_ANY, "offload", "%s ", "offload");
+	if (ext_flags & NTF_EXT_EXT_VALIDATED)
+		print_null(PRINT_ANY, "extern_valid", "%s ", "extern_valid");
 
 	if (show_stats) {
 		if (tb[NDA_CACHEINFO])
diff --git a/man/man8/ip-neighbour.8 b/man/man8/ip-neighbour.8
index 6fed47ce..1f890c0d 100644
--- a/man/man8/ip-neighbour.8
+++ b/man/man8/ip-neighbour.8
@@ -27,7 +27,8 @@ ip-neighbour \- neighbour/arp tables management.
 .BR router " ] [ "
 .BR use " ] [ "
 .BR managed " ] [ "
-.BR extern_learn " ]"
+.BR extern_learn " ] [ "
+.BR extern_valid " ]"
 
 .ti -8
 .BR "ip neigh" " { " show " | " flush " } [ " proxy " ] [ " to
@@ -115,6 +116,13 @@ this neigh entry was learned externally. This option can be used to
 indicate to the kernel that this is a controller learnt dynamic entry.
 Kernel will not gc such an entry.
 
+.TP
+.BI extern_valid
+this neigh entry was learned and determined to be valid externally. The kernel
+will not remove or invalidate the entry, but it can probe the entry and notify
+user space when the entry becomes reachable. The kernel will return the entry
+to stale state if it did not receive a confirmation after probing the entry.
+
 .TP
 .BI lladdr " LLADDRESS"
 the link layer address of the neighbour.