On Wed, Feb 5, 2025 at 11:24 PM Willem de Bruijn
<willemdebruijn.kernel@xxxxxxxxx> wrote:
>
> Jason Xing wrote:
> > The "allow_tcp_access" flag is added to indicate that the callback
> > site has a tcp_sock locked.
> >
> > Applying the new member allow_tcp_access in the existing callbacks
> > where is_fullsock is set to 1 can stop UDP socket accessing struct
> > tcp_sock and stop TCP socket without sk lock protecting does the
> > similar thing, or else it could be catastrophe leading to panic.
> >
> > To keep it simple, instead of distinguishing between read and write
> > access, users aren't allowed all read/write access to the tcp_sock
> > through the older bpf_sock_ops ctx. The new timestamping callbacks
> > can use newer helpers to read everything from a sk (e.g. bpf_core_cast),
> > so nothing is lost.
> >
> > Signed-off-by: Jason Xing <kerneljasonxing@xxxxxxxxx>
> > ---
> > include/linux/filter.h | 5 +++++
> > include/net/tcp.h | 1 +
> > net/core/filter.c | 8 ++++----
> > net/ipv4/tcp_input.c | 2 ++
> > net/ipv4/tcp_output.c | 2 ++
> > 5 files changed, 14 insertions(+), 4 deletions(-)
> >
> > diff --git a/include/linux/filter.h b/include/linux/filter.h
> > index a3ea46281595..1569e9f31a8c 100644
> > --- a/include/linux/filter.h
> > +++ b/include/linux/filter.h
> > @@ -1508,6 +1508,11 @@ struct bpf_sock_ops_kern {
> > void *skb_data_end;
> > u8 op;
> > u8 is_fullsock;
> > + u8 allow_tcp_access; /* Indicate that the callback site
> > + * has a tcp_sock locked. Then it
> > + * would be safe to access struct
> > + * tcp_sock.
> > + */
>
> perhaps no need for explicit documentation if the variable name is
> self documenting: is_locked_tcp_sock
Good suggestion. I will take it :)
Thanks,
Jason
