net: lwtunnel: handle MTU calculation in forwading

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Commit 14972cbd34 ("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: 14972cbd34 ("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>

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This commit is contained in:

Vadim Fedorenko 2021-06-25 19:21:39 +03:00 • committed by David S. Miller

parent d6765985a4

commit fade56410c

3 changed files with 22 additions and 9 deletions

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12

include/net/ip.h

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16

include/net/ip6_route.h

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