On Wed, Aug 03, 2022 at 03:59:26PM -0700, sdf@xxxxxxxxxx wrote:
> On 08/03, Martin KaFai Lau 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)
> > +{
> > + return !!current->bpf_ctx;
> > +}
>
> Good point on not needing to care about softirq!
> That actually turned even nicer :-)
>
> QQ: do we need to add a comment here about potential false-negatives?
> I see you're adding ctx to the iter, but there is still a bunch of places
> that don't use it.
Make sense. I will add a comment on the requirement that the bpf prog type
needs to setup the bpf_run_ctx.
