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Diffstat (limited to 'include/net/ip.h')
-rw-r--r--include/net/ip.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/include/net/ip.h b/include/net/ip.h
index 0f72bf8c0cbf..2d6b985d11cc 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -436,12 +436,18 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst,
bool forwarding)
{
struct net *net = dev_net(dst->dev);
+ unsigned int mtu;
if (net->ipv4.sysctl_ip_fwd_use_pmtu ||
ip_mtu_locked(dst) ||
!forwarding)
return dst_mtu(dst);
+ /* 'forwarding = true' case should always honour route mtu */
+ mtu = dst_metric_raw(dst, RTAX_MTU);
+ if (mtu)
+ return mtu;
+
return min(READ_ONCE(dst->dev->mtu), IP_MAX_MTU);
}