Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit fa246693 authored by John Fastabend's avatar John Fastabend Committed by Daniel Borkmann
Browse files

bpf: sockmap, BPF_F_INGRESS flag for BPF_SK_SKB_STREAM_VERDICT: 



Add support for the BPF_F_INGRESS flag in skb redirect helper. To
do this convert skb into a scatterlist and push into ingress queue.
This is the same logic that is used in the sk_msg redirect helper
so it should feel familiar.

Signed-off-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 2596f64c

include/linux/filter.h

+1 −0
Original line number Diff line number Diff line
@@ -521,6 +521,7 @@ struct sk_msg_buff { 
	__u32 key;

	__u32 flags;

	struct bpf_map *map;

	struct sk_buff *skb;

	struct list_head list;

};

kernel/bpf/sockmap.c

+76 −18
Original line number Diff line number Diff line
@@ -785,6 +785,7 @@ static int bpf_tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, 
				i++;

				if (i == MAX_SKB_FRAGS)

					i = 0;

				if (!md->skb)

					put_page(page);

			}

			if (copied == len)
@@ -794,6 +795,8 @@ static int bpf_tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, 


		if (!sg->length && md->sg_start == md->sg_end) {

			list_del(&md->list);

			if (md->skb)

				consume_skb(md->skb);

			kfree(md);

		}

	}
@@ -1045,27 +1048,72 @@ static int smap_verdict_func(struct smap_psock *psock, struct sk_buff *skb) 
		__SK_DROP;

}



static int smap_do_ingress(struct smap_psock *psock, struct sk_buff *skb)

{

	struct sock *sk = psock->sock;

	int copied = 0, num_sg;

	struct sk_msg_buff *r;



	r = kzalloc(sizeof(struct sk_msg_buff), __GFP_NOWARN | GFP_ATOMIC);

	if (unlikely(!r))

		return -EAGAIN;



	if (!sk_rmem_schedule(sk, skb, skb->len)) {

		kfree(r);

		return -EAGAIN;

	}



	sg_init_table(r->sg_data, MAX_SKB_FRAGS);

	num_sg = skb_to_sgvec(skb, r->sg_data, 0, skb->len);

	if (unlikely(num_sg < 0)) {

		kfree(r);

		return num_sg;

	}

	sk_mem_charge(sk, skb->len);

	copied = skb->len;

	r->sg_start = 0;

	r->sg_end = num_sg == MAX_SKB_FRAGS ? 0 : num_sg;

	r->skb = skb;

	list_add_tail(&r->list, &psock->ingress);

	sk->sk_data_ready(sk);

	return copied;

}



static void smap_do_verdict(struct smap_psock *psock, struct sk_buff *skb)

{

	struct smap_psock *peer;

	struct sock *sk;

	__u32 in;

	int rc;



	rc = smap_verdict_func(psock, skb);

	switch (rc) {

	case __SK_REDIRECT:

		sk = do_sk_redirect_map(skb);

		if (likely(sk)) {

			struct smap_psock *peer = smap_psock_sk(sk);

		if (!sk) {

			kfree_skb(skb);

			break;

		}



		peer = smap_psock_sk(sk);

		in = (TCP_SKB_CB(skb)->bpf.flags) & BPF_F_INGRESS;



			if (likely(peer &&

				   test_bit(SMAP_TX_RUNNING, &peer->state) &&

				   !sock_flag(sk, SOCK_DEAD) &&

				   sock_writeable(sk))) {

		if (unlikely(!peer || sock_flag(sk, SOCK_DEAD) ||

			     !test_bit(SMAP_TX_RUNNING, &peer->state))) {

			kfree_skb(skb);

			break;

		}



		if (!in && sock_writeable(sk)) {

			skb_set_owner_w(skb, sk);

			skb_queue_tail(&peer->rxqueue, skb);

			schedule_work(&peer->tx_work);

			break;

			}

		} else if (in &&

			   atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf) {

			skb_queue_tail(&peer->rxqueue, skb);

			schedule_work(&peer->tx_work);

			break;

		}

	/* Fall through and free skb otherwise */

	case __SK_DROP:
@@ -1127,15 +1175,23 @@ static void smap_tx_work(struct work_struct *w) 
	}



	while ((skb = skb_dequeue(&psock->rxqueue))) {

		__u32 flags;



		rem = skb->len;

		off = 0;

start:

		flags = (TCP_SKB_CB(skb)->bpf.flags) & BPF_F_INGRESS;

		do {

			if (likely(psock->sock->sk_socket))

			if (likely(psock->sock->sk_socket)) {

				if (flags)

					n = smap_do_ingress(psock, skb);

				else

					n = skb_send_sock_locked(psock->sock,

								 skb, off, rem);

			else

			} else {

				n = -EINVAL;

			}



			if (n <= 0) {

				if (n == -EAGAIN) {

					/* Retry when space is available */
@@ -1153,6 +1209,8 @@ static void smap_tx_work(struct work_struct *w) 
			rem -= n;

			off += n;

		} while (rem);



		if (!flags)

			kfree_skb(skb);

	}

out:

net/core/filter.c

+1 −1
Original line number Diff line number Diff line
@@ -1855,7 +1855,7 @@ BPF_CALL_4(bpf_sk_redirect_map, struct sk_buff *, skb, 
	struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);



	/* If user passes invalid input drop the packet. */

	if (unlikely(flags))

	if (unlikely(flags & ~(BPF_F_INGRESS)))

		return SK_DROP;



	tcb->bpf.key = key;