Re: [PATCH bpf-next v7 2/5] bpf: Expose bpf_get_socket_cookie to tracing programs

[Florent Revest <revest@chromium.org>]

On Wed, Feb 10, 2021 at 8:52 PM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Wed, Feb 10, 2021 at 3:14 AM Florent Revest <revest@chromium.org> wrote:
> >
> > This needs a new helper that:
> > - can work in a sleepable context (using sock_gen_cookie)
> > - takes a struct sock pointer and checks that it's not NULL
> >
> > Signed-off-by: Florent Revest <revest@chromium.org>
> > Acked-by: KP Singh <kpsingh@kernel.org>
> > ---
>
> It's customary to send cover letter with patch sets of 2 or more
> related patches. It's a good place to explain the motivation of a
> patch set. And a good place to ack all patches in one go ;)

You're right :) I first (naively!) thought it would be a short series
but it grew bigger than I originally thought. I will make sure I do in
the future. ;)

> Acked-by: Andrii Nakryiko <andrii@kernel.org>
>
>
> >  include/linux/bpf.h            |  1 +
> >  include/uapi/linux/bpf.h       |  8 ++++++++
> >  kernel/trace/bpf_trace.c       |  2 ++
> >  net/core/filter.c              | 12 ++++++++++++
> >  tools/include/uapi/linux/bpf.h |  8 ++++++++
> >  5 files changed, 31 insertions(+)
> >
> > diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> > index 321966fc35db..d212ae7d9731 100644
> > --- a/include/linux/bpf.h
> > +++ b/include/linux/bpf.h
> > @@ -1888,6 +1888,7 @@ extern const struct bpf_func_proto bpf_per_cpu_ptr_proto;
> >  extern const struct bpf_func_proto bpf_this_cpu_ptr_proto;
> >  extern const struct bpf_func_proto bpf_ktime_get_coarse_ns_proto;
> >  extern const struct bpf_func_proto bpf_sock_from_file_proto;
> > +extern const struct bpf_func_proto bpf_get_socket_ptr_cookie_proto;
> >
> >  const struct bpf_func_proto *bpf_tracing_func_proto(
> >         enum bpf_func_id func_id, const struct bpf_prog *prog);
> > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > index 0b735c2729b2..a8d9ad543300 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -1673,6 +1673,14 @@ union bpf_attr {
> >   *     Return
> >   *             A 8-byte long unique number.
> >   *
> > + * u64 bpf_get_socket_cookie(struct sock *sk)
> > + *     Description
> > + *             Equivalent to **bpf_get_socket_cookie**\ () helper that accepts
> > + *             *sk*, but gets socket from a BTF **struct sock**. This helper
> > + *             also works for sleepable programs.
> > + *     Return
> > + *             A 8-byte long unique number or 0 if *sk* is NULL.
> > + *
> >   * 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 6c0018abe68a..845b2168e006 100644
> > --- a/kernel/trace/bpf_trace.c
> > +++ b/kernel/trace/bpf_trace.c
> > @@ -1760,6 +1760,8 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> >                 return &bpf_sk_storage_delete_tracing_proto;
> >         case BPF_FUNC_sock_from_file:
> >                 return &bpf_sock_from_file_proto;
> > +       case BPF_FUNC_get_socket_cookie:
> > +               return &bpf_get_socket_ptr_cookie_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 e15d4741719a..57aaed478362 100644
> > --- a/net/core/filter.c
> > +++ b/net/core/filter.c
> > @@ -4631,6 +4631,18 @@ static const struct bpf_func_proto bpf_get_socket_cookie_sock_proto = {
> >         .arg1_type      = ARG_PTR_TO_CTX,
> >  };
> >
> > +BPF_CALL_1(bpf_get_socket_ptr_cookie, struct sock *, sk)
> > +{
> > +       return sk ? sock_gen_cookie(sk) : 0;
> > +}
> > +
> > +const struct bpf_func_proto bpf_get_socket_ptr_cookie_proto = {
> > +       .func           = bpf_get_socket_ptr_cookie,
> > +       .gpl_only       = false,
> > +       .ret_type       = RET_INTEGER,
> > +       .arg1_type      = ARG_PTR_TO_BTF_ID_SOCK_COMMON,
> > +};
> > +
> >  BPF_CALL_1(bpf_get_socket_cookie_sock_ops, struct bpf_sock_ops_kern *, ctx)
> >  {
> >         return __sock_gen_cookie(ctx->sk);
> > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> > index 0b735c2729b2..a8d9ad543300 100644
> > --- a/tools/include/uapi/linux/bpf.h
> > +++ b/tools/include/uapi/linux/bpf.h
> > @@ -1673,6 +1673,14 @@ union bpf_attr {
> >   *     Return
> >   *             A 8-byte long unique number.
> >   *
> > + * u64 bpf_get_socket_cookie(struct sock *sk)
> > + *     Description
> > + *             Equivalent to **bpf_get_socket_cookie**\ () helper that accepts
> > + *             *sk*, but gets socket from a BTF **struct sock**. This helper
> > + *             also works for sleepable programs.
> > + *     Return
> > + *             A 8-byte long unique number or 0 if *sk* is NULL.
> > + *
> >   * u32 bpf_get_socket_uid(struct sk_buff *skb)
> >   *     Return
> >   *             The owner UID of the socket associated to *skb*. If the socket
> > --
> > 2.30.0.478.g8a0d178c01-goog
> >