net/ipv4/netfilter/nf_tproxy_ipv4.c

Source file repositories/reference/linux-study-clean/net/ipv4/netfilter/nf_tproxy_ipv4.c

File Facts

System
Linux kernel
Corpus path
net/ipv4/netfilter/nf_tproxy_ipv4.c
Extension
.c
Size
3829 bytes
Lines
154
Domain
Networking Core
Bucket
Sockets, Protocols, Packet Path, And Network Policy
Inferred role
Networking Core: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Networking stack implementation surface: socket APIs, protocol dispatch, packet flow, routing, filtering, and network namespaces.

Dependency Surface

Detected Declarations

Annotated Snippet

if (sk2) {
			nf_tproxy_twsk_deschedule_put(inet_twsk(sk));
			sk = sk2;
		}
	}

	return sk;
}
EXPORT_SYMBOL_GPL(nf_tproxy_handle_time_wait4);

__be32 nf_tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr)
{
	const struct in_ifaddr *ifa;
	struct in_device *indev;
	__be32 laddr;

	if (user_laddr)
		return user_laddr;

	laddr = 0;
	indev = __in_dev_get_rcu(skb->dev);
	if (!indev)
		return daddr;

	in_dev_for_each_ifa_rcu(ifa, indev) {
		if (ifa->ifa_flags & IFA_F_SECONDARY)
			continue;

		laddr = ifa->ifa_local;
		break;
	}

	return laddr ? laddr : daddr;
}
EXPORT_SYMBOL_GPL(nf_tproxy_laddr4);

struct sock *
nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb,
		      const u8 protocol,
		      const __be32 saddr, const __be32 daddr,
		      const __be16 sport, const __be16 dport,
		      const struct net_device *in,
		      const enum nf_tproxy_lookup_t lookup_type)
{
	struct sock *sk;

	switch (protocol) {
	case IPPROTO_TCP: {
		struct tcphdr _hdr, *hp;

		hp = skb_header_pointer(skb, ip_hdrlen(skb),
					sizeof(struct tcphdr), &_hdr);
		if (hp == NULL)
			return NULL;

		switch (lookup_type) {
		case NF_TPROXY_LOOKUP_LISTENER:
			sk = inet_lookup_listener(net, skb,
						  ip_hdrlen(skb) + __tcp_hdrlen(hp),
						  saddr, sport, daddr, dport,
						  in->ifindex, 0);

			if (sk && !refcount_inc_not_zero(&sk->sk_refcnt))
				sk = NULL;
			/* NOTE: we return listeners even if bound to
			 * 0.0.0.0, those are filtered out in
			 * xt_socket, since xt_TPROXY needs 0 bound
			 * listeners too
			 */
			break;
		case NF_TPROXY_LOOKUP_ESTABLISHED:
			sk = inet_lookup_established(net, saddr, sport,
						     daddr, dport, in->ifindex);
			break;
		default:
			BUG();
		}
		break;
		}
	case IPPROTO_UDP:
		sk = udp4_lib_lookup(net, saddr, sport, daddr, dport,
				     in->ifindex);
		if (sk) {
			int connected = (sk->sk_state == TCP_ESTABLISHED);
			int wildcard = (inet_sk(sk)->inet_rcv_saddr == 0);

			/* NOTE: we return listeners even if bound to
			 * 0.0.0.0, those are filtered out in
			 * xt_socket, since xt_TPROXY needs 0 bound
			 * listeners too

Annotation

Implementation Notes