linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Martin KaFai Lau <kafai@fb.com>
To: Florent Revest <revest@chromium.org>
Cc: <bpf@vger.kernel.org>, <ast@kernel.org>, <daniel@iogearbox.net>,
	<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 11:47:48 -0800	[thread overview]
Message-ID: <20201204194748.cqyz7hfx5s5dyszc@kafai-mbp.dhcp.thefacebook.com> (raw)
In-Reply-To: <20201203213330.1657666-1-revest@google.com>

On Thu, Dec 03, 2020 at 10:33:28PM +0100, 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.
> + *
>   * u32 bpf_get_socket_uid(struct sk_buff *skb)
>   * 	Return
>   * 		The owner UID of the socket associated to *skb*. If the socket
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index d255bc9b2bfa..14ad96579813 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -1725,6 +1725,8 @@ raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
>  	}
>  }
>  
> +extern const struct bpf_func_proto bpf_get_socket_cookie_sock_tracing_proto;
> +
>  const struct bpf_func_proto *
>  tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
>  {
> @@ -1748,6 +1750,8 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
>  		return &bpf_sk_storage_get_tracing_proto;
>  	case BPF_FUNC_sk_storage_delete:
>  		return &bpf_sk_storage_delete_tracing_proto;
> +	case BPF_FUNC_get_socket_cookie:
> +		return &bpf_get_socket_cookie_sock_tracing_proto;
>  #endif
>  	case BPF_FUNC_seq_printf:
>  		return prog->expected_attach_type == BPF_TRACE_ITER ?
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 2ca5eecebacf..177c4e5e529d 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -4631,6 +4631,13 @@ static const struct bpf_func_proto bpf_get_socket_cookie_sock_proto = {
>  	.arg1_type	= ARG_PTR_TO_CTX,
>  };
>  
> +const struct bpf_func_proto bpf_get_socket_cookie_sock_tracing_proto = {
> +	.func		= bpf_get_socket_cookie_sock,
> +	.gpl_only	= false,
> +	.ret_type	= RET_INTEGER,
> +	.arg1_type      = ARG_PTR_TO_BTF_ID_SOCK_COMMON,
In tracing where it gets a sk pointer, the sk could be NULL.
A NULL check is required in the helper. Please refer to
bpf_skc_to_tcp_sock[_proto] as an example.

This proto is in general also useful for non tracing context where
it can get a hold of a sk pointer. (e.g. another similar usage that will
have a hold on a sk pointer for BPF_PROG_TYPE_SK_REUSEPORT [0]).
In case if you don't need sleepable at this point as Daniel
mentioned in another thread.  Does it make sense to rename this
proto to something like bpf_get_socket_pointer_cookie_proto?

[0]: https://lore.kernel.org/bpf/20201201144418.35045-10-kuniyu@amazon.co.jp/

  parent reply	other threads:[~2020-12-04 19:49 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-03 21:33 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
2020-12-08 19:30     ` Florent Revest
2020-12-09  8:29       ` Daniel Borkmann
2020-12-04 19:47 ` Martin KaFai Lau [this message]
2020-12-08 19:40   ` Florent Revest

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=20201204194748.cqyz7hfx5s5dyszc@kafai-mbp.dhcp.thefacebook.com \
    --to=kafai@fb.com \
    --cc=andrii@kernel.org \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=kpsingh@chromium.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=revest@chromium.org \
    --cc=revest@google.com \
    --subject='Re: [PATCH bpf-next v2 1/3] bpf: Expose bpf_get_socket_cookie to tracing programs' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).