linux-kernel - [PATCH wireguard v4 04/10] wireguard: netlink: lower .maxattr for WG_CMD_GET

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Message-ID: <20251126173546.57681-5-ast@fiberby.net>
Date: Wed, 26 Nov 2025 17:35:36 +0000
From: Asbjørn Sloth Tønnesen <ast@...erby.net>
To: "Jason A. Donenfeld" <Jason@...c4.com>
Cc: Asbjørn Sloth Tønnesen <ast@...erby.net>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Donald Hunter <donald.hunter@...il.com>,
	Simon Horman <horms@...nel.org>,
	Jacob Keller <jacob.e.keller@...el.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	wireguard@...ts.zx2c4.com,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Jordan Rife <jordan@...fe.io>
Subject: [PATCH wireguard v4 04/10] wireguard: netlink: lower .maxattr for WG_CMD_GET_DEVICE

Previously .maxattr was shared for both WG_CMD_GET_DEVICE and
WG_CMD_SET_DEVICE. Now that it is split, then we can lower it
for WG_CMD_GET_DEVICE to follow the documentation which defines
.maxattr as WGDEVICE_A_IFNAME for WG_CMD_GET_DEVICE.

$ grep -hC5 'one but not both of:' include/uapi/linux/wireguard.h
 * WG_CMD_GET_DEVICE
 * -----------------
 *
 * May only be called via NLM_F_REQUEST | NLM_F_DUMP. The command
 * should contain one but not both of:
 *
 *    WGDEVICE_A_IFINDEX: NLA_U32
 *    WGDEVICE_A_IFNAME: NLA_NUL_STRING, maxlen IFNAMSIZ - 1
 *
 * The kernel will then return several messages [...]

While other attributes weren't rejected previously, the consensus
is that nobody sends those attributes, so nothing should break.

Link: https://lore.kernel.org/r/aRyLoy2iqbkUipZW@zx2c4.com/
Suggested-by: Jason A. Donenfeld <Jason@...c4.com>
Signed-off-by: Asbjørn Sloth Tønnesen <ast@...erby.net>
---
 drivers/net/wireguard/netlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireguard/netlink.c b/drivers/net/wireguard/netlink.c
index e7efe5f8465dc..c2d0576e96f5f 100644
--- a/drivers/net/wireguard/netlink.c
+++ b/drivers/net/wireguard/netlink.c
@@ -623,7 +623,7 @@ static const struct genl_split_ops wireguard_nl_ops[] = {
 		.dumpit = wg_get_device_dump,
 		.done = wg_get_device_done,
 		.policy = device_policy,
-		.maxattr = WGDEVICE_A_PEERS,
+		.maxattr = WGDEVICE_A_IFNAME,
 		.flags = GENL_UNS_ADMIN_PERM | GENL_CMD_CAP_DUMP,
 	}, {
 		.cmd = WG_CMD_SET_DEVICE,
-- 
2.51.0