netdev - [PATCHv2 net 3/3] tipc: check the bearer min mtu properly when setting it by netlink

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Date: Tue,  2 May 2023 18:13:15 -0400
From: Xin Long <lucien.xin@...il.com>
To: network dev <netdev@...r.kernel.org>,
	tipc-discussion@...ts.sourceforge.net
Cc: davem@...emloft.net,
	kuba@...nel.org,
	Eric Dumazet <edumazet@...gle.com>,
	Paolo Abeni <pabeni@...hat.com>,
	Jon Maloy <jmaloy@...hat.com>,
	Tung Nguyen <tung.q.nguyen@...tech.com.au>
Subject: [PATCHv2 net 3/3] tipc: check the bearer min mtu properly when setting it by netlink

Checking the bearer min mtu with tipc_udp_mtu_bad() only works for
IPv4 UDP bearer, and IPv6 UDP bearer has a different value for the
min mtu. This patch checks with encap_hlen + TIPC_MIN_BEARER_MTU
for min mtu, which works for both IPv4 and IPv6 UDP bearer.

Note that tipc_udp_mtu_bad() is still used to check media min mtu
in __tipc_nl_media_set(), as m->mtu currently is only used by the
IPv4 UDP bearer as its default mtu value.

Fixes: 682cd3cf946b ("tipc: confgiure and apply UDP bearer MTU on running links")
Signed-off-by: Xin Long <lucien.xin@...il.com>
---
 net/tipc/bearer.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index 0e9a29e1536b..53881406e200 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c
@@ -1151,8 +1151,8 @@ int __tipc_nl_bearer_set(struct sk_buff *skb, struct genl_info *info)
 				return -EINVAL;
 			}
 #ifdef CONFIG_TIPC_MEDIA_UDP
-			if (tipc_udp_mtu_bad(nla_get_u32
-					     (props[TIPC_NLA_PROP_MTU]))) {
+			if (nla_get_u32(props[TIPC_NLA_PROP_MTU]) <
+			    b->encap_hlen + TIPC_MIN_BEARER_MTU) {
 				NL_SET_ERR_MSG(info->extack,
 					       "MTU value is out-of-range");
 				return -EINVAL;
-- 
2.39.1