diff options
| author | Alexei Starovoitov <ast@plumgrid.com> | 2015-06-04 20:11:53 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-06-07 12:01:33 +0300 |
| commit | 3431205e03977aaf32bce6d4b16fb8244b510056 (patch) | |
| tree | 0d9405acb8ac34a6bc5ad93a9b9ae674c4d3879e /net/sched/act_bpf.c | |
| parent | 98da81a426a76c351f3c2854d5bc31f17bba3194 (diff) | |
| download | linux-3431205e03977aaf32bce6d4b16fb8244b510056.tar.xz | |
bpf: make programs see skb->data == L2 for ingress and egress
eBPF programs attached to ingress and egress qdiscs see inconsistent skb->data.
For ingress L2 header is already pulled, whereas for egress it's present.
This is known to program writers which are currently forced to use
BPF_LL_OFF workaround.
Since programs don't change skb internal pointers it is safe to do
pull/push right around invocation of the program and earlier taps and
later pt->func() will not be affected.
Multiple taps via packet_rcv(), tpacket_rcv() are doing the same trick
around run_filter/BPF_PROG_RUN even if skb_shared.
This fix finally allows programs to use optimized LD_ABS/IND instructions
without BPF_LL_OFF for higher performance.
tc ingress + cls_bpf + samples/bpf/tcbpf1_kern.o
w/o JIT w/JIT
before 20.5 23.6 Mpps
after 21.8 26.6 Mpps
Old programs with BPF_LL_OFF will still work as-is.
We can now undo most of the earlier workaround commit:
a166151cbe33 ("bpf: fix bpf helpers to use skb->mac_header relative offsets")
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched/act_bpf.c')
| -rw-r--r-- | net/sched/act_bpf.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/net/sched/act_bpf.c b/net/sched/act_bpf.c index dc6a2d324bd8..1d56903fd4c7 100644 --- a/net/sched/act_bpf.c +++ b/net/sched/act_bpf.c @@ -37,6 +37,7 @@ static int tcf_bpf(struct sk_buff *skb, const struct tc_action *act, { struct tcf_bpf *prog = act->priv; int action, filter_res; + bool at_ingress = G_TC_AT(skb->tc_verd) & AT_INGRESS; if (unlikely(!skb_mac_header_was_set(skb))) return TC_ACT_UNSPEC; @@ -48,7 +49,13 @@ static int tcf_bpf(struct sk_buff *skb, const struct tc_action *act, /* Needed here for accessing maps. */ rcu_read_lock(); - filter_res = BPF_PROG_RUN(prog->filter, skb); + if (at_ingress) { + __skb_push(skb, skb->mac_len); + filter_res = BPF_PROG_RUN(prog->filter, skb); + __skb_pull(skb, skb->mac_len); + } else { + filter_res = BPF_PROG_RUN(prog->filter, skb); + } rcu_read_unlock(); /* A BPF program may overwrite the default action opcode. |