linux-kernel - [PATCH net-next v2 1/3] netlink: specs: fou: change local-v6/peer-v6 check

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Message-ID: <20250902154640.759815-2-ast@fiberby.net>
Date: Tue,  2 Sep 2025 15:46:35 +0000
From: Asbjørn Sloth Tønnesen <ast@...erby.net>
To: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>
Cc: Asbjørn Sloth Tønnesen <ast@...erby.net>,
	Donald Hunter <donald.hunter@...il.com>,
	Simon Horman <horms@...nel.org>,
	Jacob Keller <jacob.e.keller@...el.com>,
	"Matthieu Baerts (NGI0)" <matttbe@...nel.org>,
	David Ahern <dsahern@...nel.org>,
	Chuck Lever <chuck.lever@...cle.com>,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH net-next v2 1/3] netlink: specs: fou: change local-v6/peer-v6 check

While updating the binary min-len implementation, I noticed that
the only user, should AFAICT be using exact-len instead.

In net/ipv4/fou_core.c FOU_ATTR_LOCAL_V6 and FOU_ATTR_PEER_V6
are only used for singular IPv6 addresses, and there are AFAICT
no known implementations trying to send more, it therefore
appears safe to change it to an exact-len policy.

This patch therefore changes the local-v6/peer-v6 attributes to
use an exact-len check, instead of a min-len check.

Signed-off-by: Asbjørn Sloth Tønnesen <ast@...erby.net>
---
 Documentation/netlink/specs/fou.yaml | 4 ++--
 net/ipv4/fou_nl.c                    | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/Documentation/netlink/specs/fou.yaml b/Documentation/netlink/specs/fou.yaml
index 57735726262ec..8e7974ec453fc 100644
--- a/Documentation/netlink/specs/fou.yaml
+++ b/Documentation/netlink/specs/fou.yaml
@@ -52,7 +52,7 @@ attribute-sets:
         name: local-v6
         type: binary
         checks:
-          min-len: 16
+          exact-len: 16
       -
         name: peer-v4
         type: u32
@@ -60,7 +60,7 @@ attribute-sets:
         name: peer-v6
         type: binary
         checks:
-          min-len: 16
+          exact-len: 16
       -
         name: peer-port
         type: u16
diff --git a/net/ipv4/fou_nl.c b/net/ipv4/fou_nl.c
index 3d9614609b2d3..506260b4a4dc2 100644
--- a/net/ipv4/fou_nl.c
+++ b/net/ipv4/fou_nl.c
@@ -18,9 +18,9 @@ const struct nla_policy fou_nl_policy[FOU_ATTR_IFINDEX + 1] = {
 	[FOU_ATTR_TYPE] = { .type = NLA_U8, },
 	[FOU_ATTR_REMCSUM_NOPARTIAL] = { .type = NLA_FLAG, },
 	[FOU_ATTR_LOCAL_V4] = { .type = NLA_U32, },
-	[FOU_ATTR_LOCAL_V6] = { .len = 16, },
+	[FOU_ATTR_LOCAL_V6] = NLA_POLICY_EXACT_LEN(16),
 	[FOU_ATTR_PEER_V4] = { .type = NLA_U32, },
-	[FOU_ATTR_PEER_V6] = { .len = 16, },
+	[FOU_ATTR_PEER_V6] = NLA_POLICY_EXACT_LEN(16),
 	[FOU_ATTR_PEER_PORT] = { .type = NLA_BE16, },
 	[FOU_ATTR_IFINDEX] = { .type = NLA_S32, },
 };
-- 
2.50.1