From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
Jiri Olsa <jolsa@redhat.com>,
Eelco Chaudron <echaudro@redhat.com>,
KP Singh <kpsingh@chromium.org>,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>
Subject: Re: [PATCH bpf-next v7 03/10] bpf: verifier: refactor check_attach_btf_id()
Date: Tue, 22 Sep 2020 12:14:10 +0200 [thread overview]
Message-ID: <87o8lyp18t.fsf@toke.dk> (raw)
In-Reply-To: <CAEf4BzY4UR+KjZ3bY6ykyW5CPNwAzwgKVhYHGdgDuMT2nntmTg@mail.gmail.com>
Andrii Nakryiko <andrii.nakryiko@gmail.com> writes:
> On Sat, Sep 19, 2020 at 4:50 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>>
>> From: Toke Høiland-Jørgensen <toke@redhat.com>
>>
>> The check_attach_btf_id() function really does three things:
>>
>> 1. It performs a bunch of checks on the program to ensure that the
>> attachment is valid.
>>
>> 2. It stores a bunch of state about the attachment being requested in
>> the verifier environment and struct bpf_prog objects.
>>
>> 3. It allocates a trampoline for the attachment.
>>
>> This patch splits out (1.) and (3.) into separate functions in preparation
>> for reusing them when the actual attachment is happening (in the
>> raw_tracepoint_open syscall operation), which will allow tracing programs
>> to have multiple (compatible) attachments.
>>
>> No functional change is intended with this patch.
>>
>> Acked-by: Andrii Nakryiko <andriin@fb.com>
>> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
>> ---
>
> Ok, so bad news: you broke another selftest (test_overhead). Please,
> do run test_progs and make sure everything succeeds, every time before
> you post a new version.
Ah, right, I'll take a look. I have had some trouble with running all
the tests because my VM runs out of memory, so I was picking and
choosing. Guess I'll go and actually fix this and run the full test
suite...
> Good news, though, is that this refactoring actually fixed a pretty
> nasty bug in check_attach_btf_id logic: whenever bpf_trampoline
> already existed (e.g., due to successful fentry to function X), all
> subsequent fentry/fexit/fmod_ret and all their sleepable variants
> would skip a bunch of check. So please attach the following Fixes
> tags:
>
> Fixes: 6ba43b761c41 ("bpf: Attachment verification for BPF_MODIFY_RETURN")
> Fixes: 1e6c62a88215 ("bpf: Introduce sleepable BPF programs")
Ah, yes, well spotted! Will add the Fixes tags :)
> As for selftests, feel free to just drop the fmod_ret program, it was
> never supposed to be possible, I just never realized that.
Well, doesn't hurt to have it, does it? If you don't mind I think I'll
just keep it...
-Toke
next prev parent reply other threads:[~2020-09-22 10:14 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-19 11:49 [PATCH bpf-next v7 00/10] bpf: Support multi-attach for freplace programs Toke Høiland-Jørgensen
2020-09-19 11:49 ` [PATCH bpf-next v7 01/10] bpf: disallow attaching modify_return tracing functions to other BPF programs Toke Høiland-Jørgensen
2020-09-21 22:39 ` Andrii Nakryiko
2020-09-22 9:52 ` Toke Høiland-Jørgensen
2020-09-19 11:49 ` [PATCH bpf-next v7 02/10] bpf: change logging calls from verbose() to bpf_log() and use log pointer Toke Høiland-Jørgensen
2020-09-19 11:49 ` [PATCH bpf-next v7 03/10] bpf: verifier: refactor check_attach_btf_id() Toke Høiland-Jørgensen
2020-09-21 23:05 ` Andrii Nakryiko
2020-09-22 10:14 ` Toke Høiland-Jørgensen [this message]
2020-09-22 11:16 ` Toke Høiland-Jørgensen
2020-09-22 16:28 ` Andrii Nakryiko
2020-09-22 17:41 ` Toke Høiland-Jørgensen
2020-09-19 11:49 ` [PATCH bpf-next v7 04/10] bpf: move prog->aux->linked_prog and trampoline into bpf_link on attach Toke Høiland-Jørgensen
2020-09-21 23:05 ` Andrii Nakryiko
2020-09-22 10:17 ` Toke Høiland-Jørgensen
2020-09-22 16:45 ` Andrii Nakryiko
2020-09-22 17:48 ` Toke Høiland-Jørgensen
2020-09-19 11:49 ` [PATCH bpf-next v7 05/10] bpf: support attaching freplace programs to multiple attach points Toke Høiland-Jørgensen
2020-09-21 23:08 ` Andrii Nakryiko
2020-09-19 11:49 ` [PATCH bpf-next v7 06/10] bpf: Fix context type resolving for extension programs Toke Høiland-Jørgensen
2020-09-21 23:09 ` Andrii Nakryiko
2020-09-19 11:49 ` [PATCH bpf-next v7 07/10] libbpf: add support for freplace attachment in bpf_link_create Toke Høiland-Jørgensen
2020-09-21 23:18 ` Andrii Nakryiko
2020-09-19 11:49 ` [PATCH bpf-next v7 08/10] selftests: add test for multiple attachments of freplace program Toke Høiland-Jørgensen
2020-09-21 23:21 ` Andrii Nakryiko
2020-09-19 11:49 ` [PATCH bpf-next v7 09/10] selftests/bpf: Adding test for arg dereference in extension trace Toke Høiland-Jørgensen
2020-09-19 11:49 ` [PATCH bpf-next v7 10/10] selftests: Add selftest for disallowing modify_return attachment to freplace Toke Høiland-Jørgensen
2020-09-21 23:25 ` Andrii Nakryiko
2020-09-21 23:26 ` [PATCH bpf-next v7 00/10] bpf: Support multi-attach for freplace programs Andrii Nakryiko
2020-09-22 9:48 ` Toke Høiland-Jørgensen
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