Hi. There is the workaround - classify the packets with iptables+ipset - it's enough fast and more friendly.
On Fri, 4 Jan 2019 at 00:21, Bartek Kois <bartek.k...@gmail.com> wrote: > > Hi > 1. What exactly caused this change in the kernel? > 2. I don`t understand why adding VLAN tag, which is just 4 additional > bytes to the passing packet make it impossible to classify. > 3. This whole thing makes the QoS under Linux routers hard to configure > in scenarios with more than one VLAN which is pretty much every slightly > bigger router nowadays especially if we use IFB and hashing filters. Is > there any walkaround for that problem? > > Best regards > Bartek Kois > > W dniu 03.01.2019 o 04:30, Cong Wang pisze: > > On Tue, Jan 1, 2019 at 11:46 AM Bartek Kois <bartek.k...@gmail.com> wrote: > >> Hi > >> Yes it did work since I remember (like around 2.4.x) and it changed > >> since I moved from Debian 8 to 9. I would appreciate fixing that in the > >> future beacuse it is essential for queueing traffic on the routers, but > >> the question is why these filters don`t work in that case: > >> > >> tc filter add dev $LAN_ETH parent 1:0 protocol ip prio 4 u32 match > >> u32 0x0a000c08 0xffffffff at 20 classid 1:2001 # for 10.0.12.8 ip > >> address > >> tc filter add dev $LAN_ETH parent 1:0 protocol ip prio 4 u32 match > >> u32 0x0a000c09 0xffffffff at 20 classid 1:2002 # for 10.0.12.9 ip > >> address > >> tc filter add dev $LAN_ETH parent 1:0 protocol ip prio 4 u32 match > >> u32 0x0a000c10 0xffffffff at 20 classid 1:2003 # for 10.0.12.10 ip > >> address > >> > >> I`ve changed "at 16" which works without vlan tags to "at 20" to take > >> vlan tag into account. > > Yeah, this confirms my speculation. > > > > The problem is essentially a design flaw of u32 filter, the IP header > > and TCP header offsets are never fixed, for example VLAN tagging and > > IP options. What's more, it is not easy for user-space to learn the offset > > for different packets as it requires to parse into each packets. > > > > I don't know whether we can fix this either, VLAN call path probably > > already makes assumptions on the current skb->data position, if > > we "fix" it for u32, it would probably break other things. -- Anton.
