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netkit: Assign missing bpf_net_context

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During the introduction of struct bpf_net_context handling for
XDP-redirect, the netkit driver has been missed, which also requires it
because NETKIT_REDIRECT invokes skb_do_redirect() which is accessing the
per-CPU variables. Otherwise we see the following crash:

	BUG: kernel NULL pointer dereference, address: 0000000000000038
	bpf_redirect()
	netkit_xmit()
	dev_hard_start_xmit()

Set the bpf_net_context before invoking netkit_xmit() program within the
netkit driver.

Fixes: 401cb7dae8 ("net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.")
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20240912155620.1334587-1-leitao@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Breno Leitao 2024-09-12 08:56:19 -07:00 committed by Jakub Kicinski
parent 4144a1059b
commit 157f29152b
1 changed files with 3 additions and 0 deletions
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3
drivers/net/netkit.c
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@ -65,6 +65,7 @@ static struct netkit *netkit_priv(const struct net_device *dev)
static netdev_tx_t netkit_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
struct netkit *nk = netkit_priv(dev);
enum netkit_action ret = READ_ONCE(nk->policy);
netdev_tx_t ret_dev = NET_XMIT_SUCCESS;
@ -72,6 +73,7 @@ static netdev_tx_t netkit_xmit(struct sk_buff *skb, struct net_device *dev)
struct net_device *peer;
int len = skb->len;
bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
rcu_read_lock();
peer = rcu_dereference(nk->peer);
if (unlikely(!peer || !(peer->flags & IFF_UP) ||
@ -110,6 +112,7 @@ drop_stats:
break;
}
rcu_read_unlock();
bpf_net_ctx_clear(bpf_net_ctx);
return ret_dev;
}