lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Mon, 07 Dec 2020 13:03:28 +0100 From: Toke Høiland-Jørgensen <toke@...hat.com> To: Daniel Borkmann <daniel@...earbox.net>, Maciej Fijalkowski <maciej.fijalkowski@...el.com>, Jesper Dangaard Brouer <brouer@...hat.com> Cc: alardam@...il.com, magnus.karlsson@...el.com, bjorn.topel@...el.com, andrii.nakryiko@...il.com, kuba@...nel.org, ast@...nel.org, netdev@...r.kernel.org, davem@...emloft.net, john.fastabend@...il.com, hawk@...nel.org, jonathan.lemon@...il.com, bpf@...r.kernel.org, jeffrey.t.kirsher@...el.com, maciejromanfijalkowski@...il.com, intel-wired-lan@...ts.osuosl.org, Marek Majtyka <marekx.majtyka@...el.com> Subject: Re: [PATCH v2 bpf 1/5] net: ethtool: add xdp properties flag set Daniel Borkmann <daniel@...earbox.net> writes: > On 12/4/20 6:20 PM, Toke Høiland-Jørgensen wrote: >> Daniel Borkmann <daniel@...earbox.net> writes: > [...] >>> We tried to standardize on a minimum guaranteed amount, but unfortunately not >>> everyone seems to implement it, but I think it would be very useful to query >>> this from application side, for example, consider that an app inserts a BPF >>> prog at XDP doing custom encap shortly before XDP_TX so it would be useful to >>> know which of the different encaps it implements are realistically possible on >>> the underlying XDP supported dev. >> >> How many distinct values are there in reality? Enough to express this in >> a few flags (XDP_HEADROOM_128, XDP_HEADROOM_192, etc?), or does it need >> an additional field to get the exact value? If we implement the latter >> we also run the risk of people actually implementing all sorts of weird >> values, whereas if we constrain it to a few distinct values it's easier >> to push back against adding new values (as it'll be obvious from the >> addition of new flags). > > It's not everywhere straight forward to determine unfortunately, see also [0,1] > as some data points where Jesper looked into in the past, so in some cases it > might differ depending on the build/runtime config.. > > [0] https://lore.kernel.org/bpf/158945314698.97035.5286827951225578467.stgit@firesoul/ > [1] https://lore.kernel.org/bpf/158945346494.97035.12809400414566061815.stgit@firesoul/ Right, well in that case maybe we should just expose the actual headroom as a separate netlink attribute? Although I suppose that would require another round of driver changes since Jesper's patch you linked above only puts this into xdp_buff at XDP program runtime. Jesper, WDYT? -Toke
Powered by blists - more mailing lists