leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

bpf: Compute data_end dynamically with JIT code

Browse Source 
Currently, we compute ->data_end with a compile-time constant
offset of skb. But as Jakub pointed out, we can actually compute
it in eBPF JIT code at run-time, so that we can competely get
rid of ->data_end. This is similar to skb_shinfo(skb) computation
in bpf_convert_shinfo_access().

Suggested-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20210223184934.6054-4-xiyou.wangcong@gmail.com
This commit is contained in:
Cong Wang
2021-02-23 10:49:28 -08:00
committed by Alexei Starovoitov
parent 5a685cd94b
commit 16137b09a6
3 changed files with 28 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
include/net/tcp.h
View File

@@ -886,18 +886,12 @@ struct tcp_skb_cb {
struct {
__u32 flags;
struct sock *sk_redir;
void *data_end;
} bpf;
};
};
#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
static inline void bpf_compute_data_end_sk_skb(struct sk_buff *skb)
{
TCP_SKB_CB(skb)->bpf.data_end = skb->data + skb_headlen(skb);
}
static inline bool tcp_skb_bpf_ingress(const struct sk_buff *skb)
{
return TCP_SKB_CB(skb)->bpf.flags & BPF_F_INGRESS;