Commit 36cd0e69 authored by John Fastabend's avatar John Fastabend Committed by Daniel Borkmann
Browse files

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: 51199405 ("bpf: skb_verdict, support SK_PASS on RX BPF path")
Suggested-by: default avatarJakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: default avatarJakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/160556568657.73229.8404601585878439060.stgit@john-XPS-13-9370
parent c9c89dcd

net/core/skmsg.c

+16 −4
Original line number Diff line number Diff line
@@ -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;



	/* When the skb owns the memory we free it from consume_skb path. */

	if (!msg->skb) {

		if (charge)

			sk_mem_uncharge(sk, len);

	if (!msg->skb)

		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;

net/ipv4/tcp_bpf.c

+2 −1
Original line number Diff line number Diff line
@@ -45,6 +45,7 @@ int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock, 
			if (likely(!peek)) {

				sge->offset += copy;

				sge->length -= copy;

				if (!msg_rx->skb)

					sk_mem_uncharge(sk, copy);

				msg_rx->sg.size -= copy;

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