netdev - Re: [Patch net] net_sched: refetch skb protocol for each filter

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Date:   Sat, 12 Jan 2019 10:41:24 -0500
From:   Jamal Hadi Salim <jhs@...atatu.com>
To:     Cong Wang <xiyou.wangcong@...il.com>, netdev@...r.kernel.org
Cc:     Martin Olsson <martin.olsson+netdev@...torsecurity.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Lucas Bates <lucasb@...atatu.com>
Subject: Re: [Patch net] net_sched: refetch skb protocol for each filter

On 2019-01-12 7:23 a.m., Jamal Hadi Salim wrote:

> Do we have a test case for a setup like this in tdc?
> i.e incoming tagged and then vlan popped by action?
> Otherwise a test with IFE which resets the ethertype
> would be sufficient i.e just something that will messup
> with skb->protocol.

And here is a slightly complex test with IFE.
Wanted to show both reclassify and continue in play
as well as something that change skb->protocol.

I used VMs to test, but two hosts or two containers
with veth between them will do.
Martin, if you have the cycles please test this out.

TLDR: Suspect is the vlan part.

-----------
#Sender side egress setup. We are going to encode
#all outgoing pings(icmp) to carry an skbmark 17 on the wire
#and set the ethertype  to 0xDEAD
sudo $TC qdisc del dev $ETH root
sudo $TC qdisc add dev $ETH root handle 1: prio
sudo $TC filter add dev $ETH parent 1: protocol ip prio 10 u32 \
match ip protocol 1 0xff \
flowid 1:2 \
action skbedit mark 17 \
action ife encode type 0xDEAD allow mark

#receiver side ingress setup

sudo $TC qdisc del dev $ETH ingress
sudo $TC qdisc add dev $ETH ingress
#decapsulate based on skb proto and then
#reclassify
sudo $TC filter add dev $ETH parent ffff: prio 2 protocol 0xdead u32 \
match u32 0 0 flowid 1:1 action ife decode reclassify
#match icmp
sudo $TC filter add dev $ETH parent ffff: prio 4 protocol ip u32 \
match ip protocol 1 0xff flowid 1:1 action continue
#
#now classify based on mark 17 (hex 11).
#
sudo $TC filter add dev $ETH parent ffff: prio 5 protocol ip \
handle 0x11 fw flowid 1:1 \
action ok

On sender side, send 10 pings to receiver. Now lets see
the receiver stats:

---------------
root@...-foobar:# uname -a
Linux jhs-foobar 4.20.0-rc7+ #2 SMP Fri Jan 12 9:29:35 EST 2019 x86_64 
x86_64 x86_64 GNU/Linux

root@...-foobar:# $TC -s filter ls dev $ETH parent ffff:
filter protocol [57005] pref 2 u32
filter protocol [57005] pref 2 u32 fh 800: ht divisor 1
filter protocol [57005] pref 2 u32 fh 800::800 order 2048 key ht 800 bkt 
0 flowid 1:1  (rule hit 10 success 10)
   match 00000000/00000000 at 0 (success 10 )
	action order 1: ife decode action reclassify type 0x0
	 allow mark allow prio
	 index 1 ref 1 bind 1 installed 40 sec used 19 sec
	Action statistics:
	Sent 1080 bytes 10 pkt (dropped 0, overlimits 0 requeues 0)
	backlog 0b 0p requeues 0

filter protocol ip pref 4 u32
filter protocol ip pref 4 u32 fh 801: ht divisor 1
filter protocol ip pref 4 u32 fh 801::800 order 2048 key ht 801 bkt 0 
flowid 1:1  (rule hit 33 success 10)
   match 00010000/00ff0000 at 8 (success 10 )
	action order 1: gact action continue
	 random type none pass val 0
	 index 1 ref 1 bind 1 installed 40 sec used 19 sec
  	Action statistics:
	Sent 1080 bytes 10 pkt (dropped 0, overlimits 0 requeues 0)
	backlog 0b 0p requeues 0

filter protocol ip pref 5 fw
filter protocol ip pref 5 fw handle 0x11 classid 1:1

	action order 1: gact action pass
	 random type none pass val 0
	 index 2 ref 1 bind 1 installed 39 sec used 19 sec
  	Action statistics:
	Sent 1080 bytes 10 pkt (dropped 0, overlimits 0 requeues 0)
	backlog 0b 0p requeues 0
---------------


As can be observed all the rules are hit as expected.

cheers,
jamal