On 6/12/23 13:17, Alexei Starovoitov wrote:
On Mon, Jun 12, 2023 at 12:16 PM Kui-Feng Lee <thinker.li@xxxxxxxxx> wrote:
Always call BPF filters if CGROUP BPF is enabled for EGRESS without
checking skb->sk against sk.
The filters were called only if sk_buff is owned by the sock that the
sk_buff is sent out through. In another words, sk_buff::sk should point to
What is "sk_buff::sk" ? Did you mean skb->sk ?
Yes!
the sock that it is sending through its egress. However, the filters would
miss SYNACK sk_buffs that they are owned by a request_sock but sent through
the listening sock, that is the socket listening incoming connections.
This is an unnecessary restrict.
Signed-off-by: Kui-Feng Lee <kuifeng@xxxxxxxx>
---
include/linux/bpf-cgroup.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index 57e9e109257e..e656da531f9f 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -199,7 +199,7 @@ static inline bool cgroup_bpf_sock_enabled(struct sock *sk,
#define BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb) \
({ \
int __ret = 0; \
- if (cgroup_bpf_enabled(CGROUP_INET_EGRESS) && sk && sk == skb->sk) { \
+ if (cgroup_bpf_enabled(CGROUP_INET_EGRESS) && sk) {
I did a bit of git-archeology.
That check was there since the beginning of cgroup-bpf and
came as a suggestion to use 'sk' instead of 'skb->sk':
https://lore.kernel.org/all/58193E9D.7040201@xxxxxxxxxxxxx/
Using sk is certainly correct. It looks to me that the check
was added just for a "piece of mind".
Good to know that. Thank you for the confirmation.
