On Thu, Aug 04, 2022 at 12:03:04PM -0700, Andrii Nakryiko wrote:
> On Wed, Aug 3, 2022 at 1:49 PM Martin KaFai Lau <kafai@xxxxxx> wrote:
> >
> > Most of the code in bpf_setsockopt(SOL_SOCKET) are duplicated from
> > the sk_setsockopt(). The number of supported optnames are
> > increasing ever and so as the duplicated code.
> >
> > One issue in reusing sk_setsockopt() is that the bpf prog
> > has already acquired the sk lock. This patch adds a in_bpf()
> > to tell if the sk_setsockopt() is called from a bpf prog.
> > The bpf prog calling bpf_setsockopt() is either running in_task()
> > or in_serving_softirq(). Both cases have the current->bpf_ctx
> > initialized. Thus, the in_bpf() only needs to test !!current->bpf_ctx.
> >
> > This patch also adds sockopt_{lock,release}_sock() helpers
> > for sk_setsockopt() to use. These helpers will test in_bpf()
> > before acquiring/releasing the lock. They are in EXPORT_SYMBOL
> > for the ipv6 module to use in a latter patch.
> >
> > Note on the change in sock_setbindtodevice(). sockopt_lock_sock()
> > is done in sock_setbindtodevice() instead of doing the lock_sock
> > in sock_bindtoindex(..., lock_sk = true).
> >
> > Signed-off-by: Martin KaFai Lau <kafai@xxxxxx>
> > ---
> > include/linux/bpf.h | 8 ++++++++
> > include/net/sock.h | 3 +++
> > net/core/sock.c | 26 +++++++++++++++++++++++---
> > 3 files changed, 34 insertions(+), 3 deletions(-)
> >
> > diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> > index 20c26aed7896..b905b1b34fe4 100644
> > --- a/include/linux/bpf.h
> > +++ b/include/linux/bpf.h
> > @@ -1966,6 +1966,10 @@ static inline bool unprivileged_ebpf_enabled(void)
> > return !sysctl_unprivileged_bpf_disabled;
> > }
> >
> > +static inline bool in_bpf(void)
>
> I think this function deserves a big comment explaining that it's not
> 100% accurate, as not every BPF program type sets bpf_ctx. As it is
> named in_bpf() promises a lot more generality than it actually
> provides.
>
> Should this be named either more specific has_current_bpf_ctx() maybe?
Stans also made a similar point on this to add comment.
Rename makes sense until all bpf prog has bpf_ctx. in_bpf() was
just the name it was used in the v1 discussion for the setsockopt
context.
> Also, separately, should be make an effort to set bpf_ctx for all
> program types (instead or in addition to the above)?
I would prefer to separate this as a separate effort. This set is
getting pretty long and the bpf_getsockopt() is still not posted.
If you prefer this must be done first, I can do that also.
