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xfrm: fix disable_xfrm sysctl when used on xfrm interfaces

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The disable_xfrm flag signals that xfrm should not be performed during
routing towards a device before reaching device xmit.

For xfrm interfaces this is usually desired as they perform the outbound
policy lookup as part of their xmit using their if_id.

Before this change enabling this flag on xfrm interfaces prevented them
from xmitting as xfrm_lookup_with_ifid() would not perform a policy lookup
in case the original dst had the DST_NOXFRM flag.

This optimization is incorrect when the lookup is done by the xfrm
interface xmit logic.

Fix by performing policy lookup when invoked by xfrmi as if_id != 0.

Similarly it's unlikely for the 'no policy exists on net' check to yield
any performance benefits when invoked from xfrmi.

Fixes: f203b76d78 ("xfrm: Add virtual xfrm interfaces")
Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
This commit is contained in:
Eyal Birger 2020-12-23 17:00:46 +02:00 committed by Steffen Klassert
parent 56ce7c25ae
commit 9f8550e4bd
1 changed files with 2 additions and 2 deletions
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4
net/xfrm/xfrm_policy.c
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@ -3078,8 +3078,8 @@ struct dst_entry *xfrm_lookup_with_ifid(struct net *net,
xflo.flags = flags;
/* To accelerate a bit... */
if ((dst_orig->flags & DST_NOXFRM) ||
!net->xfrm.policy_count[XFRM_POLICY_OUT])
if (!if_id && ((dst_orig->flags & DST_NOXFRM) ||
!net->xfrm.policy_count[XFRM_POLICY_OUT]))
goto nopol;
xdst = xfrm_bundle_lookup(net, fl, family, dir, &xflo, if_id);