From: John Fastabend <john.fastab...@gmail.com> Date: Sun, 18 Mar 2018 12:57:25 -0700
> Currently, if a bpf sk msg program is run the program > can only parse data that the (start,end) pointers already > consumed. For sendmsg hooks this is likely the first > scatterlist element. For sendpage this will be the range > (0,0) because the data is shared with userspace and by > default we want to avoid allowing userspace to modify > data while (or after) BPF verdict is being decided. > > To support pulling in additional bytes for parsing use > a new helper bpf_sk_msg_pull(start, end, flags) which > works similar to cls tc logic. This helper will attempt > to point the data start pointer at 'start' bytes offest > into msg and data end pointer at 'end' bytes offset into > message. ... > Signed-off-by: John Fastabend <john.fastab...@gmail.com> Acked-by: David S. Miller <da...@davemloft.net>
