netdev - Re: [PATCH RFC bpf-next v2 1/5] netlink: specs: Add XDP RX checksum capability to XDP metadata specs

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 linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aNcZdfCivLR2slFw@mini-arch>
Date: Fri, 26 Sep 2025 15:53:41 -0700
From: Stanislav Fomichev <stfomichev@...il.com>
To: Jesper Dangaard Brouer <hawk@...nel.org>
Cc: Lorenzo Bianconi <lorenzo@...nel.org>,
	Donald Hunter <donald.hunter@...il.com>,
	Jakub Kicinski <kuba@...nel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
	Simon Horman <horms@...nel.org>,
	Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	John Fastabend <john.fastabend@...il.com>,
	Stanislav Fomichev <sdf@...ichev.me>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	Tony Nguyen <anthony.l.nguyen@...el.com>,
	Przemek Kitszel <przemyslaw.kitszel@...el.com>,
	Alexander Lobakin <aleksander.lobakin@...el.com>,
	Andrii Nakryiko <andrii@...nel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>,
	Yonghong Song <yonghong.song@...ux.dev>,
	KP Singh <kpsingh@...nel.org>, Hao Luo <haoluo@...gle.com>,
	Jiri Olsa <jolsa@...nel.org>, Shuah Khan <shuah@...nel.org>,
	Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
	netdev@...r.kernel.org, bpf@...r.kernel.org,
	intel-wired-lan@...ts.osuosl.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH RFC bpf-next v2 1/5] netlink: specs: Add XDP RX checksum
 capability to XDP metadata specs

On 09/26, Jesper Dangaard Brouer wrote:
> 
> 
> On 26/09/2025 06.20, Stanislav Fomichev wrote:
> > On 09/25, Lorenzo Bianconi wrote:
> > > Introduce XDP RX checksum capability to XDP metadata specs. XDP RX
> > > checksum will be use by devices capable of exposing receive checksum
> > > result via bpf_xdp_metadata_rx_checksum().
> > > Moreover, introduce xmo_rx_checksum netdev callback in order allow the
> > > eBPF program bounded to the device to retrieve the RX checksum result
> > > computed by the hw NIC.
> > > 
> > > Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
> > > ---
> > >   Documentation/netlink/specs/netdev.yaml |  5 +++++
> > >   include/net/xdp.h                       | 14 ++++++++++++++
> > >   net/core/xdp.c                          | 29 +++++++++++++++++++++++++++++
> > >   3 files changed, 48 insertions(+)
> > > 
> > > diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml
> > > index e00d3fa1c152d7165e9485d6d383a2cc9cef7cfd..00699bf4a7fdb67c6b9ee3548098b0c933fd39a4 100644
> > > --- a/Documentation/netlink/specs/netdev.yaml
> > > +++ b/Documentation/netlink/specs/netdev.yaml
> > > @@ -61,6 +61,11 @@ definitions:
> > >           doc: |
> > >             Device is capable of exposing receive packet VLAN tag via
> > >             bpf_xdp_metadata_rx_vlan_tag().
> > > +      -
> > > +        name: checksum
> > > +        doc: |
> > > +          Device is capable of exposing receive checksum result via
> > > +          bpf_xdp_metadata_rx_checksum().
> > >     -
> > >       type: flags
> > >       name: xsk-flags
> > > diff --git a/include/net/xdp.h b/include/net/xdp.h
> > > index aa742f413c358575396530879af4570dc3fc18de..9ab9ac10ae2074b70618a9d4f32544d8b9a30b63 100644
> > > --- a/include/net/xdp.h
> > > +++ b/include/net/xdp.h
> > > @@ -586,6 +586,10 @@ void xdp_attachment_setup(struct xdp_attachment_info *info,
> > >   			   NETDEV_XDP_RX_METADATA_VLAN_TAG, \
> > >   			   bpf_xdp_metadata_rx_vlan_tag, \
> > >   			   xmo_rx_vlan_tag) \
> > > +	XDP_METADATA_KFUNC(XDP_METADATA_KFUNC_RX_CHECKSUM, \
> > > +			   NETDEV_XDP_RX_METADATA_CHECKSUM, \
> > > +			   bpf_xdp_metadata_rx_checksum, \
> > > +			   xmo_rx_checksum)
> > >   enum xdp_rx_metadata {
> > >   #define XDP_METADATA_KFUNC(name, _, __, ___) name,
> > > @@ -643,12 +647,22 @@ enum xdp_rss_hash_type {
> > >   	XDP_RSS_TYPE_L4_IPV6_SCTP_EX = XDP_RSS_TYPE_L4_IPV6_SCTP | XDP_RSS_L3_DYNHDR,
> > >   };
> > > +enum xdp_checksum {
> > > +	XDP_CHECKSUM_NONE		= CHECKSUM_NONE,
> > > +	XDP_CHECKSUM_UNNECESSARY	= CHECKSUM_UNNECESSARY,
> > > +	XDP_CHECKSUM_COMPLETE		= CHECKSUM_COMPLETE,
> > > +	XDP_CHECKSUM_PARTIAL		= CHECKSUM_PARTIAL,
> > > +};
> > 
> > Btw, might be worth mentioning, awhile ago we had settled on a smaller set of
> > exposed types:
> > 
> > https://lore.kernel.org/netdev/20230811161509.19722-13-larysa.zaremba@intel.com/
> > 
> > Maybe go through the previous postings and check if the arguments are
> > still relevant? (or explain why we want more checksum now)
> 
> IHMO the linked proposal reduced the types too much.

IIRC, PARTIAL was removed because it's mostly (or only) a TX feature?
So no real need to expose it as an rx hint. And I think empty xdp_csum_status
in that proposal might have indicated NONE?