From: Jakub Sitnicki <jakub@cloudflare•com>
To: Jiayuan Chen <mrpre@163•com>
Cc: bpf@vger•kernel.org, john.fastabend@gmail•com,
netdev@vger•kernel.org, martin.lau@linux•dev, ast@kernel•org,
edumazet@google•com, davem@davemloft•net, dsahern@kernel•org,
kuba@kernel•org, pabeni@redhat•com,
linux-kernel@vger•kernel.org, song@kernel•org,
andrii@kernel•org, mhal@rbox•co, yonghong.song@linux•dev,
daniel@iogearbox•net, xiyou.wangcong@gmail•com,
horms@kernel•org, corbet@lwn•net, eddyz87@gmail•com,
cong.wang@bytedance•com, shuah@kernel•org, mykolal@fb•com,
jolsa@kernel•org, haoluo@google•com, sdf@fomichev•me,
kpsingh@kernel•org, linux-doc@vger•kernel.org
Subject: Re: [PATCH bpf v5 1/3] bpf: fix wrong copied_seq calculation
Date: Tue, 14 Jan 2025 12:27:46 +0100 [thread overview]
Message-ID: <87o709eitp.fsf@cloudflare.com> (raw)
In-Reply-To: <20250109094402.50838-2-mrpre@163.com> (Jiayuan Chen's message of "Thu, 9 Jan 2025 17:43:59 +0800")
On Thu, Jan 09, 2025 at 05:43 PM +08, Jiayuan Chen wrote:
> 'sk->copied_seq' was updated in the tcp_eat_skb() function when the
> action of a BPF program was SK_REDIRECT. For other actions, like SK_PASS,
> the update logic for 'sk->copied_seq' was moved to
> tcp_bpf_recvmsg_parser() to ensure the accuracy of the 'fionread' feature.
>
> It works for a single stream_verdict scenario, as it also modified
> 'sk_data_ready->sk_psock_verdict_data_ready->tcp_read_skb'
> to remove updating 'sk->copied_seq'.
>
> However, for programs where both stream_parser and stream_verdict are
> active(strparser purpose), tcp_read_sock() was used instead of
> tcp_read_skb() (sk_data_ready->strp_data_ready->tcp_read_sock)
> tcp_read_sock() now still update 'sk->copied_seq', leading to duplicated
> updates.
>
> In summary, for strparser + SK_PASS, copied_seq is redundantly calculated
> in both tcp_read_sock() and tcp_bpf_recvmsg_parser().
>
> The issue causes incorrect copied_seq calculations, which prevent
> correct data reads from the recv() interface in user-land.
>
> We do not want to add new proto_ops to implement a new version of
> tcp_read_sock, as this would introduce code complexity [1].
>
> [1]: https://lore.kernel.org/bpf/20241218053408.437295-1-mrpre@163.com
> Fixes: e5c6de5fa025 ("bpf, sockmap: Incorrectly handling copied_seq")
> Co-developed-by: Jakub Sitnicki <jakub@cloudflare•com>
> Signed-off-by: Jakub Sitnicki <jakub@cloudflare•com>
> Signed-off-by: Jiayuan Chen <mrpre@163•com>
> ---
No need to put me down as an author.
If you want you can me with a Suggested-by.
Also, please remove my Signed-off-by.
I will review these patches, but I haven't authored them.
next prev parent reply other threads:[~2025-01-14 11:27 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-09 9:43 [PATCH bpf v5 0/3] bpf: fix wrong copied_seq calculation and add tests Jiayuan Chen
2025-01-09 9:43 ` [PATCH bpf v5 1/3] bpf: fix wrong copied_seq calculation Jiayuan Chen
2025-01-14 0:04 ` Jakub Kicinski
2025-01-14 6:35 ` Jiayuan Chen
2025-01-14 18:01 ` Jakub Kicinski
2025-01-14 11:27 ` Jakub Sitnicki [this message]
2025-01-09 9:44 ` [PATCH bpf v5 2/3] selftests/bpf: add strparser test for bpf Jiayuan Chen
2025-01-09 9:44 ` [PATCH bpf v5 3/3] bpf, strparser, docs: Add new callback " Jiayuan Chen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87o709eitp.fsf@cloudflare.com \
--to=jakub@cloudflare$(echo .)com \
--cc=andrii@kernel$(echo .)org \
--cc=ast@kernel$(echo .)org \
--cc=bpf@vger$(echo .)kernel.org \
--cc=cong.wang@bytedance$(echo .)com \
--cc=corbet@lwn$(echo .)net \
--cc=daniel@iogearbox$(echo .)net \
--cc=davem@davemloft$(echo .)net \
--cc=dsahern@kernel$(echo .)org \
--cc=eddyz87@gmail$(echo .)com \
--cc=edumazet@google$(echo .)com \
--cc=haoluo@google$(echo .)com \
--cc=horms@kernel$(echo .)org \
--cc=john.fastabend@gmail$(echo .)com \
--cc=jolsa@kernel$(echo .)org \
--cc=kpsingh@kernel$(echo .)org \
--cc=kuba@kernel$(echo .)org \
--cc=linux-doc@vger$(echo .)kernel.org \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=martin.lau@linux$(echo .)dev \
--cc=mhal@rbox$(echo .)co \
--cc=mrpre@163$(echo .)com \
--cc=mykolal@fb$(echo .)com \
--cc=netdev@vger$(echo .)kernel.org \
--cc=pabeni@redhat$(echo .)com \
--cc=sdf@fomichev$(echo .)me \
--cc=shuah@kernel$(echo .)org \
--cc=song@kernel$(echo .)org \
--cc=xiyou.wangcong@gmail$(echo .)com \
--cc=yonghong.song@linux$(echo .)dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox