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authorVadim Fedorenko <vfedorenko@novek.ru>2021-06-25 19:21:39 +0300
committerDavid S. Miller <davem@davemloft.net>2021-06-28 12:42:14 -0700
commitfade56410c22cacafb1be9f911a0afd3701d8366 (patch)
tree842aa81df2724b2eca90b7f5aad43fc8f9512e8f /net/ipv4
parentd6765985a42a660f078896d5c5b27f97c580a490 (diff)
downloadlinux-fade56410c22cacafb1be9f911a0afd3701d8366.tar.bz2
net: lwtunnel: handle MTU calculation in forwading
Commit 14972cbd34ff ("net: lwtunnel: Handle fragmentation") moved fragmentation logic away from lwtunnel by carry encap headroom and use it in output MTU calculation. But the forwarding part was not covered and created difference in MTU for output and forwarding and further to silent drops on ipv4 forwarding path. Fix it by taking into account lwtunnel encap headroom. The same commit also introduced difference in how to treat RTAX_MTU in IPv4 and IPv6 where latter explicitly removes lwtunnel encap headroom from route MTU. Make IPv4 version do the same. Fixes: 14972cbd34ff ("net: lwtunnel: Handle fragmentation") Suggested-by: David Ahern <dsahern@gmail.com> Signed-off-by: Vadim Fedorenko <vfedorenko@novek.ru> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/route.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 6a36ac98476f..78d1e5afc452 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1306,7 +1306,7 @@ INDIRECT_CALLABLE_SCOPE unsigned int ipv4_mtu(const struct dst_entry *dst)
mtu = dst_metric_raw(dst, RTAX_MTU);
if (mtu)
- return mtu;
+ goto out;
mtu = READ_ONCE(dst->dev->mtu);
@@ -1315,6 +1315,7 @@ INDIRECT_CALLABLE_SCOPE unsigned int ipv4_mtu(const struct dst_entry *dst)
mtu = 576;
}
+out:
mtu = min_t(unsigned int, mtu, IP_MAX_MTU);
return mtu - lwtunnel_headroom(dst->lwtstate, mtu);