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authorAlexei Starovoitov <ast@plumgrid.com>2015-06-04 10:11:53 -0700
committerDavid S. Miller <davem@davemloft.net>2015-06-07 02:01:33 -0700
commit3431205e03977aaf32bce6d4b16fb8244b510056 (patch)
tree0d9405acb8ac34a6bc5ad93a9b9ae674c4d3879e /net/sched/cls_bpf.c
parent98da81a426a76c351f3c2854d5bc31f17bba3194 (diff)
downloadlinux-3431205e03977aaf32bce6d4b16fb8244b510056.tar.bz2
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/cls_bpf.c')
-rw-r--r--net/sched/cls_bpf.c16
1 files changed, 15 insertions, 1 deletions
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;