From: John Fastabend john.fastabend@gmail.com
[ Upstream commit cfea28f890cf292d5fe90680db64b68086ef25ba ]
For sk_skb case where skb_verdict program returns SK_PASS to continue to pass packet up the stack, the memory limits were already checked before enqueuing in skb_queue_tail from TCP side. So, lets remove the extra checks here. The theory is if the TCP stack believes we have memory to receive the packet then lets trust the stack and not double check the limits.
In fact the accounting here can cause a drop if sk_rmem_alloc has increased after the stack accepted this packet, but before the duplicate check here. And worse if this happens because TCP stack already believes the data has been received there is no retransmit.
Fixes: 51199405f9672 ("bpf: skb_verdict, support SK_PASS on RX BPF path") Signed-off-by: John Fastabend john.fastabend@gmail.com Signed-off-by: Alexei Starovoitov ast@kernel.org Link: https://lore.kernel.org/bpf/160226857664.5692.668205469388498375.stgit@john-... Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/skmsg.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-)
diff --git a/net/core/skmsg.c b/net/core/skmsg.c index 1f8e3445cd2f0..605c48df7eb68 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -765,6 +765,7 @@ EXPORT_SYMBOL_GPL(sk_psock_tls_strp_read); static void sk_psock_verdict_apply(struct sk_psock *psock, struct sk_buff *skb, int verdict) { + struct tcp_skb_cb *tcp; struct sock *sk_other;
switch (verdict) { @@ -774,16 +775,12 @@ static void sk_psock_verdict_apply(struct sk_psock *psock, !sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED)) { goto out_free; } - if (atomic_read(&sk_other->sk_rmem_alloc) <= - sk_other->sk_rcvbuf) { - struct tcp_skb_cb *tcp = TCP_SKB_CB(skb);
- tcp->bpf.flags |= BPF_F_INGRESS; - skb_queue_tail(&psock->ingress_skb, skb); - schedule_work(&psock->work); - break; - } - goto out_free; + tcp = TCP_SKB_CB(skb); + tcp->bpf.flags |= BPF_F_INGRESS; + skb_queue_tail(&psock->ingress_skb, skb); + schedule_work(&psock->work); + break; case __SK_REDIRECT: sk_psock_skb_redirect(skb); break;