From: Daniel Borkmann <daniel@iogearbox.net>
To: Florent Revest <revest@chromium.org>, bpf@vger.kernel.org
Cc: ast@kernel.org, andrii@kernel.org, kpsingh@chromium.org,
revest@google.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf-next v2 1/3] bpf: Expose bpf_get_socket_cookie to tracing programs
Date: Fri, 4 Dec 2020 20:03:40 +0100 [thread overview]
Message-ID: <7c70a64f-1aba-0e11-983d-9338f25a367e@iogearbox.net> (raw)
In-Reply-To: <bdd7153b-4bf9-12dd-5950-df0ebe91659d@iogearbox.net>
On 12/4/20 7:56 PM, Daniel Borkmann wrote:
> On 12/3/20 10:33 PM, Florent Revest wrote:
>> This creates a new helper proto because the existing
>> bpf_get_socket_cookie_sock_proto has a ARG_PTR_TO_CTX argument and only
>> works for BPF programs where the context is a sock.
>>
>> This helper could also be useful to other BPF program types such as LSM.
>>
>> Signed-off-by: Florent Revest <revest@google.com>
>> ---
>> include/uapi/linux/bpf.h | 7 +++++++
>> kernel/trace/bpf_trace.c | 4 ++++
>> net/core/filter.c | 7 +++++++
>> tools/include/uapi/linux/bpf.h | 7 +++++++
>> 4 files changed, 25 insertions(+)
>>
>> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
>> index c3458ec1f30a..3e0e33c43998 100644
>> --- a/include/uapi/linux/bpf.h
>> +++ b/include/uapi/linux/bpf.h
>> @@ -1662,6 +1662,13 @@ union bpf_attr {
>> * Return
>> * A 8-byte long non-decreasing number.
>> *
>> + * u64 bpf_get_socket_cookie(void *sk)
>> + * Description
>> + * Equivalent to **bpf_get_socket_cookie**\ () helper that accepts
>> + * *sk*, but gets socket from a BTF **struct sock**.
>> + * Return
>> + * A 8-byte long non-decreasing number.
>
> I would not mention this here since it's not fully correct and we should avoid users
> taking non-decreasing granted in their progs. The only assumption you can make is
> that it can be considered a unique number. See also [0] with reverse counter..
>
> [0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=92acdc58ab11af66fcaef485433fde61b5e32fac
One more thought, in case you plan to use this from sleepable context, you would
need to use sock_gen_cookie() variant in the BPF helper instead.
next prev parent reply other threads:[~2020-12-04 19:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-03 21:33 [PATCH bpf-next v2 1/3] bpf: Expose bpf_get_socket_cookie to tracing programs Florent Revest
2020-12-03 21:33 ` [PATCH bpf-next v2 2/3] selftests/bpf: Integrate the socket_cookie test to test_progs Florent Revest
2020-12-03 21:33 ` [PATCH bpf-next v2 3/3] bpf: Add a selftest for the tracing bpf_get_socket_cookie Florent Revest
2020-12-04 18:56 ` [PATCH bpf-next v2 1/3] bpf: Expose bpf_get_socket_cookie to tracing programs Daniel Borkmann
2020-12-04 19:03 ` Daniel Borkmann [this message]
2020-12-08 19:30 ` Florent Revest
2020-12-09 8:29 ` Daniel Borkmann
2020-12-04 19:47 ` Martin KaFai Lau
2020-12-08 19:40 ` Florent Revest
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