From: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>
To: "John Fastabend" <john.fastabend@gmail.com>,
<mptcp@lists.linux.dev>, <bpf@vger.kernel.org>,
<netdev@vger.kernel.org>
Cc: <daniel@iogearbox.net>, <andrii@kernel.org>, <eddyz87@gmail.com>,
<memxor@gmail.com>, <jakub@cloudflare.com>,
<jiayuan.chen@linux.dev>, <davem@davemloft.net>,
<edumazet@kernel.org>, <kuba@kernel.org>, <pabeni@redhat.com>,
<horms@kernel.org>, <kuniyu@google.com>, <willemb@google.com>,
<matttbe@kernel.org>, <mason@kernel.org>, <josef@toxicpanda.com>
Subject: Re: [PATCH bpf v2 03/15] bpf, sockmap: Don't let an SK_PASS verdict cover the next message
Date: Mon, 02 Nov 2026 22:44:58 +0000 [thread overview]
Message-ID: <DML3865PENEX.2KBDIHWGWBJ7N@gmail.com> (raw)
In-Reply-To: <tnw1v9.qyjuvdc9kq45@gmail.com>
On Mon, Nov 02, 2026 at 10:51 AM John Fastabend <john.fastabend@gmail.com> wrote:
>>+ /* A part of it may have gone out */
>>+ sk_msg_apply_bytes(psock, origsize - msg->sg.size);
>>+ /* Another sender can use up the rest during the push */
>
> Interesting. We've never hit this with http parsers. We do use this to
> skip payloads some times.
That one needs two senders on one socket.
With one sender per socket you can't hit it.
A non-blocking send() fills sndbuf in the middle of the push.
N bytes go out and tcp_bpf_push() returns -EAGAIN.
Today apply_bytes still includes these N bytes.
Then the prog doesn't see the first N bytes after the payload.
There is no error and no splat, so it's easy to miss.
next prev parent reply other threads:[~2026-11-02 22:44 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-02 7:20 [PATCH bpf v2 00/15] bpf, sockmap: Fixes for verdicts, redirects, corks and recvmsg() Alexei Starovoitov
2026-11-02 7:20 ` [PATCH bpf v2 01/15] bpf, sockmap: Write sg.start when recvmsg() faults Alexei Starovoitov
2026-11-02 8:32 ` Jiayuan Chen
2026-11-02 7:20 ` [PATCH bpf v2 02/15] bpf, sockmap: Don't let an SK_DROP verdict stick Alexei Starovoitov
2026-11-02 8:45 ` Jiayuan Chen
2026-11-02 18:47 ` John Fastabend
2026-11-02 7:21 ` [PATCH bpf v2 03/15] bpf, sockmap: Don't let an SK_PASS verdict cover the next message Alexei Starovoitov
2026-11-02 18:51 ` John Fastabend
2026-11-02 22:44 ` Alexei Starovoitov [this message]
2026-11-02 7:21 ` [PATCH bpf v2 04/15] bpf, sockmap: Subtract all dropped bytes from the return value Alexei Starovoitov
2026-11-02 11:19 ` Jiayuan Chen
2026-11-02 19:12 ` John Fastabend
2026-11-02 7:21 ` [PATCH bpf v2 05/15] bpf, sockmap: Clear the resume state of a stopped psock Alexei Starovoitov
2026-11-02 11:40 ` Jiayuan Chen
2026-11-02 19:16 ` John Fastabend
2026-11-02 7:21 ` [PATCH bpf v2 06/15] bpf, sockmap: Give no progs to a TCP listener Alexei Starovoitov
2026-11-02 12:00 ` Jiayuan Chen
2026-11-02 19:31 ` John Fastabend
2026-11-02 7:21 ` [PATCH bpf v2 07/15] bpf, sockmap: Check the target of an egress redirect before each send Alexei Starovoitov
2026-11-02 12:32 ` Jiayuan Chen
2026-11-02 16:18 ` Alexei Starovoitov
2026-11-02 19:36 ` John Fastabend
2026-11-02 7:21 ` [PATCH bpf v2 08/15] net: Leave sk_stream_wait_memory() once the socket is dead Alexei Starovoitov
2026-11-02 12:54 ` Jiayuan Chen
2026-11-02 7:21 ` [PATCH bpf v2 09/15] bpf, sockmap: Check the TCP state in recvmsg() Alexei Starovoitov
2026-11-02 15:15 ` Jiayuan Chen
2026-11-02 16:57 ` Matthieu Baerts
2026-11-02 7:21 ` [PATCH bpf v2 10/15] bpf, sockmap: Reset the copy position when corking Alexei Starovoitov
2026-11-03 1:39 ` Jiayuan Chen
2026-11-02 7:21 ` [PATCH bpf v2 11/15] bpf, sockmap: Don't copy 0 bytes into a full cork Alexei Starovoitov
2026-11-03 1:41 ` Jiayuan Chen
2026-11-02 7:21 ` [PATCH bpf v2 12/15] bpf, sockmap: Clear the redirect target before the sk_msg prog runs Alexei Starovoitov
2026-11-03 1:58 ` Jiayuan Chen
2026-11-02 7:21 ` [PATCH bpf v2 13/15] bpf, sockmap: Check that the redirected message is the cork Alexei Starovoitov
2026-11-03 2:07 ` Jiayuan Chen
2026-11-02 7:21 ` [PATCH bpf v2 14/15] bpf, sockmap: Keep the rest of the cork after a redirect Alexei Starovoitov
2026-11-03 2:25 ` Jiayuan Chen
2026-11-02 7:21 ` [PATCH bpf v2 15/15] bpf, sockmap: Clear the end mark of elements added by push and pop Alexei Starovoitov
2026-11-03 2:51 ` Jiayuan Chen
2026-11-02 9:29 ` [PATCH bpf v2 00/15] bpf, sockmap: Fixes for verdicts, redirects, corks and recvmsg() MPTCP CI
2026-11-02 20:11 ` John Fastabend
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