From 3431205e03977aaf32bce6d4b16fb8244b510056 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 4 Jun 2015 10:11:53 -0700 Subject: 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 Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller --- net/sched/cls_bpf.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) (limited to 'net/sched/cls_bpf.c') diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c index 91bd9c19471d..c79ecfd36e0f 100644 --- a/net/sched/cls_bpf.c +++ b/net/sched/cls_bpf.c @@ -64,6 +64,11 @@ static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp, { struct cls_bpf_head *head = rcu_dereference_bh(tp->root); struct cls_bpf_prog *prog; +#ifdef CONFIG_NET_CLS_ACT + bool at_ingress = G_TC_AT(skb->tc_verd) & AT_INGRESS; +#else + bool at_ingress = false; +#endif int ret = -1; if (unlikely(!skb_mac_header_was_set(skb))) @@ -72,7 +77,16 @@ static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp, /* Needed here for accessing maps. */ rcu_read_lock(); list_for_each_entry_rcu(prog, &head->plist, link) { - int filter_res = BPF_PROG_RUN(prog->filter, skb); + int filter_res; + + if (at_ingress) { + /* It is safe to push/pull even if skb_shared() */ + __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); + } if (filter_res == 0) continue; -- cgit v1.2.1