* net/ipv4/route.c: Routing anomaly introduced by 89aef89 (ipv4: Delete routing cache.)
@ 2013-07-08 8:34 Shmulik Ladkani
2013-07-09 5:43 ` Julian Anastasov
0 siblings, 1 reply; 3+ messages in thread
From: Shmulik Ladkani @ 2013-07-08 8:34 UTC (permalink / raw)
To: David S. Miller; +Cc: Alexey Kuznetsov, netdev, eyal.birger
Hi,
In 89aef89 (ipv4: Delete routing cache) the following was removed from
ip_route_input_common (nowadays named ip_route_input_noref):
- tos &= IPTOS_RT_MASK;
As a side effect, the 'tos' argument passed to 'ip_route_input_slow' is
the "raw" u8, as present in iph->tos (opposed to the formerly "masked"
value).
This may affect the route calculation, as this value is later placed in
fl4.flowi4_tos for matching purposes (using equality to the tos stored
in the FIB Rule and/or Route).
(BTW, the question whether applying the historical IPTOS_RT_MASK
prior route lookup is interesting on its own...)
However, 89aef89 created an anomaly - since in the output path, routing
*still* uses the IPTOS_RT_MASK (see __ip_route_output_key for example).
It seems the omission of 'tos &= IPTOS_RT_MASK' from
'ip_route_input_noref' was accidental.
We should align input/output behavior by reverting the omission, or
alternatively we may reconsider the entire IPTOS_RT_MASK thing.
Regards,
Shmulik
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: net/ipv4/route.c: Routing anomaly introduced by 89aef89 (ipv4: Delete routing cache.)
2013-07-08 8:34 net/ipv4/route.c: Routing anomaly introduced by 89aef89 (ipv4: Delete routing cache.) Shmulik Ladkani
@ 2013-07-09 5:43 ` Julian Anastasov
2013-07-09 9:28 ` Shmulik Ladkani
0 siblings, 1 reply; 3+ messages in thread
From: Julian Anastasov @ 2013-07-09 5:43 UTC (permalink / raw)
To: Shmulik Ladkani; +Cc: David S. Miller, Alexey Kuznetsov, netdev, eyal.birger
Hello,
On Mon, 8 Jul 2013, Shmulik Ladkani wrote:
> Hi,
>
> In 89aef89 (ipv4: Delete routing cache) the following was removed from
> ip_route_input_common (nowadays named ip_route_input_noref):
>
> - tos &= IPTOS_RT_MASK;
>
> As a side effect, the 'tos' argument passed to 'ip_route_input_slow' is
> the "raw" u8, as present in iph->tos (opposed to the formerly "masked"
> value).
>
> This may affect the route calculation, as this value is later placed in
> fl4.flowi4_tos for matching purposes (using equality to the tos stored
> in the FIB Rule and/or Route).
>
> (BTW, the question whether applying the historical IPTOS_RT_MASK
> prior route lookup is interesting on its own...)
>
> However, 89aef89 created an anomaly - since in the output path, routing
> *still* uses the IPTOS_RT_MASK (see __ip_route_output_key for example).
>
> It seems the omission of 'tos &= IPTOS_RT_MASK' from
> 'ip_route_input_noref' was accidental.
Agreed
> We should align input/output behavior by reverting the omission, or
> alternatively we may reconsider the entire IPTOS_RT_MASK thing.
The right thing should be to use tos &= IPTOS_RT_MASK
at beginning of ip_route_input_noref.
Regards
--
Julian Anastasov <ja@ssi.bg>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: net/ipv4/route.c: Routing anomaly introduced by 89aef89 (ipv4: Delete routing cache.)
2013-07-09 5:43 ` Julian Anastasov
@ 2013-07-09 9:28 ` Shmulik Ladkani
0 siblings, 0 replies; 3+ messages in thread
From: Shmulik Ladkani @ 2013-07-09 9:28 UTC (permalink / raw)
To: Julian Anastasov; +Cc: David S. Miller, Alexey Kuznetsov, netdev, eyal.birger
On Tue, 9 Jul 2013 08:43:14 +0300 (EEST) Julian Anastasov <ja@ssi.bg> wrote:
> > It seems the omission of 'tos &= IPTOS_RT_MASK' from
> > 'ip_route_input_noref' was accidental.
>
> Agreed
>
> > We should align input/output behavior by reverting the omission, or
> > alternatively we may reconsider the entire IPTOS_RT_MASK thing.
>
> The right thing should be to use tos &= IPTOS_RT_MASK
> at beginning of ip_route_input_noref.
Agreed. Will post a patch.
Regards,
Shmulik
^ permalink raw reply [flat|nested] 3+ messages in thread
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2013-07-08 8:34 net/ipv4/route.c: Routing anomaly introduced by 89aef89 (ipv4: Delete routing cache.) Shmulik Ladkani
2013-07-09 5:43 ` Julian Anastasov
2013-07-09 9:28 ` Shmulik Ladkani
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