On Sat, Mar 03, 2018 at 09:57:15PM +0100, Daniel Borkmann wrote:
> On 03/03/2018 05:02 PM, Daniel Axtens wrote:
> >> From: Daniel Axtens <d...@axtens.net>
> >>
> >> SCTP GSO skbs have a gso_size of GSO_BY_FRAGS, so any sort of
> >> unconditionally mangling of that will result in nonsense value
> >> and would corrupt the skb later on.
> >>
> >> Therefore, i) add two helpers skb_increase_gso_size() and
> >> skb_decrease_gso_size() that would throw a one time warning and
> >> bail out for such skbs and ii) refuse and return early with an
> >> error in those BPF helpers that are affected. We do need to bail
> >> out as early as possible from there before any changes on the
> >> skb have been performed.
> >>
> >> Fixes: 6578171a7ff0 ("bpf: add bpf_skb_change_proto helper")
> >> Co-authored-by: Daniel Borkmann <dan...@iogearbox.net>
> >> Signed-off-by: Daniel Axtens <d...@axtens.net>
> >> Cc: Marcelo Ricardo Leitner <marcelo.leit...@gmail.com>
> >> Acked-by: Alexei Starovoitov <a...@kernel.org>
> >
> > I've looked over your changes and they all look good to me.
> >
> >> +/* Note: Should be called only if skb_is_gso(skb) is true */
> >> +static inline bool skb_is_gso_sctp(const struct sk_buff *skb)
> >> +{
> >> + return skb_shinfo(skb)->gso_type & SKB_GSO_SCTP;
> >> +}
> >> +
> >
> > This helper is a fantastic idea and I will send a docs update to
> > highlight it.
>
> Sounds good. There are infact several places in the code that
> could make use of this right away. If you have a chance, this
> could be done in net-next along with the doc update or so.
Applied to bpf tree, Thanks everyone.
