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Date: Sat, 3 Mar 2018 21:57:15 +0100 From: Daniel Borkmann <daniel@...earbox.net> To: Daniel Axtens <dja@...ens.net>, ast@...nel.org Cc: netdev@...r.kernel.org, Marcelo Ricardo Leitner <marcelo.leitner@...il.com> Subject: Re: [PATCH bpf] bpf: fix bpf_skb_adjust_net/bpf_skb_proto_xlat to deal with gso sctp skbs On 03/03/2018 05:02 PM, Daniel Axtens wrote: >> From: Daniel Axtens <dja@...ens.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 <daniel@...earbox.net> >> Signed-off-by: Daniel Axtens <dja@...ens.net> >> Cc: Marcelo Ricardo Leitner <marcelo.leitner@...il.com> >> Acked-by: Alexei Starovoitov <ast@...nel.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. Thanks, Daniel
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