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bpf, sockmap: Ensure SO_RCVBUF memory is observed on ingress redirect 

Fix sockmap sk_skb programs so that they observe sk_rcvbuf limits. This
allows users to tune SO_RCVBUF and sockmap will honor them.

We can refactor the if(charge) case out in later patches. But, keep this
fix to the point.

Fixes: 51199405f9 ("bpf: skb_verdict, support SK_PASS on RX BPF path")
Suggested-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/160556568657.73229.8404601585878439060.stgit@john-XPS-13-9370
zero-sugar-mainline-defconfig
John Fastabend 2020-11-16 14:28:06 -08:00 committed by Daniel Borkmann
parent c9c89dcd87
commit 36cd0e696a
2 changed files with 18 additions and 5 deletions
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20
net/core/skmsg.c
View File

@ -170,10 +170,12 @@ static int sk_msg_free_elem(struct sock *sk, struct sk_msg *msg, u32 i,
struct scatterlist *sge = sk_msg_elem(msg, i);
u32 len = sge->length;
if (charge)
sk_mem_uncharge(sk, len);
if (!msg->skb)
/* When the skb owns the memory we free it from consume_skb path. */
if (!msg->skb) {
if (charge)
sk_mem_uncharge(sk, len);
put_page(sg_page(sge));
}
memset(sge, 0, sizeof(*sge));
return len;
}
@ -403,6 +405,9 @@ static int sk_psock_skb_ingress(struct sk_psock *psock, struct sk_buff *skb)
int copied = 0, num_sge;
struct sk_msg *msg;
if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf)
return -EAGAIN;
msg = kzalloc(sizeof(*msg), __GFP_NOWARN | GFP_ATOMIC);
if (unlikely(!msg))
return -EAGAIN;
@ -418,7 +423,14 @@ static int sk_psock_skb_ingress(struct sk_psock *psock, struct sk_buff *skb)
return num_sge;
}
sk_mem_charge(sk, skb->len);
/* This will transition ownership of the data from the socket where
* the BPF program was run initiating the redirect to the socket
* we will eventually receive this data on. The data will be released
* from skb_consume found in __tcp_bpf_recvmsg() after its been copied
* into user buffers.
*/
skb_set_owner_r(skb, sk);
copied = skb->len;
msg->sg.start = 0;
msg->sg.size = copied;

3
net/ipv4/tcp_bpf.c
View File

@ -45,7 +45,8 @@ int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock,
if (likely(!peek)) {
sge->offset += copy;
sge->length -= copy;
sk_mem_uncharge(sk, copy);
if (!msg_rx->skb)
sk_mem_uncharge(sk, copy);
msg_rx->sg.size -= copy;
if (!sge->length) {