The maximum packet offset accessed by one BPF program is useful information.
Because sometimes there could be packet split and it is possible for some reasons (for example performance) we want to reject the BPF program if the maximum packet size would trigger such split. Normally, MTU value is treated as the maximum packet size, but one BPF program does not always access the whole packet, it could only access the head portion of the data. We could let verifier calculate the maximum packet offset ever used and record it inside prog auxiliar information structure as a new field "max_pkt_offset". Jiong Wang (2): bpf: let verifier to calculate and record max_pkt_offset nfp: bpf: relax prog rejection through max_pkt_offset drivers/net/ethernet/netronome/nfp/bpf/offload.c | 9 +++++---- include/linux/bpf.h | 1 + kernel/bpf/verifier.c | 12 ++++++++++++ 3 files changed, 18 insertions(+), 4 deletions(-) -- 2.7.4
