Commit 114039b3 authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Martin KaFai Lau
Browse files

bpf: Move skb->len == 0 checks into __bpf_redirect 



To avoid potentially breaking existing users.

Both mac/no-mac cases have to be amended; mac_header >= network_header
is not enough (verified with a new test, see next patch).

Fixes: fd189422 ("bpf: Don't redirect packets with invalid pkt_len")
Signed-off-by: default avatarStanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20221121180340.1983627-1-sdf@google.com


Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
parent 8589e926

net/bpf/test_run.c

+0 −3
Original line number Diff line number Diff line
@@ -979,9 +979,6 @@ static int convert___skb_to_skb(struct sk_buff *skb, struct __sk_buff *__skb) 
{

	struct qdisc_skb_cb *cb = (struct qdisc_skb_cb *)skb->cb;



	if (!skb->len)

		return -EINVAL;



	if (!__skb)

		return 0;

net/core/filter.c

+6 −5
Original line number Diff line number Diff line
@@ -2124,13 +2124,14 @@ static int __bpf_redirect_no_mac(struct sk_buff *skb, struct net_device *dev, 
{

	unsigned int mlen = skb_network_offset(skb);



	if (mlen) {

		__skb_pull(skb, mlen);

		if (unlikely(!skb->len)) {

	if (unlikely(skb->len <= mlen)) {

		kfree_skb(skb);

		return -ERANGE;

	}



	if (mlen) {

		__skb_pull(skb, mlen);



		/* At ingress, the mac header has already been pulled once.

		 * At egress, skb_pospull_rcsum has to be done in case that

		 * the skb is originated from ingress (i.e. a forwarded skb)
@@ -2149,7 +2150,7 @@ static int __bpf_redirect_common(struct sk_buff *skb, struct net_device *dev, 
				 u32 flags)

{

	/* Verify that a link layer header is carried */

	if (unlikely(skb->mac_header >= skb->network_header)) {

	if (unlikely(skb->mac_header >= skb->network_header || skb->len == 0)) {

		kfree_skb(skb);

		return -ERANGE;

	}