int sk_filter_trim_cap(struct sock *sk, struct sk_buff *skb, unsigned int cap)
{
	int err;
	struct sk_filter *filter;

	/*
	 * If the skb was allocated from pfmemalloc reserves, only
	 * allow SOCK_MEMALLOC sockets to use it as this socket is
	 * helping free memory
	 */
	if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC)) {
		NET_INC_STATS(sock_net(sk), LINUX_MIB_PFMEMALLOCDROP);
		return -ENOMEM;
	}
	err = BPF_CGROUP_RUN_PROG_INET_INGRESS(sk, skb);
	if (err)
		return err;

	err = security_sock_rcv_skb(sk, skb);
	if (err)
		return err;

	rcu_read_lock();
	filter = rcu_dereference(sk->sk_filter);
	if (filter) {
		struct sock *save_sk = skb->sk;
		unsigned int pkt_len;

		skb->sk = sk;
		pkt_len = bpf_prog_run_save_cb(filter->prog, skb);
		skb->sk = save_sk;
		err = pkt_len ? pskb_trim(skb, max(cap, pkt_len)) : -EPERM;
	}
	rcu_read_unlock();

	return err;
}
Unknown