1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _NF_NAT_H
3 #define _NF_NAT_H
4 
5 #include <linux/list.h>
6 #include <linux/netfilter_ipv4.h>
7 #include <linux/netfilter/nf_conntrack_pptp.h>
8 #include <net/netfilter/nf_conntrack.h>
9 #include <net/netfilter/nf_conntrack_extend.h>
10 #include <net/netfilter/nf_conntrack_tuple.h>
11 #include <uapi/linux/netfilter/nf_nat.h>
12 
13 enum nf_nat_manip_type {
14 	NF_NAT_MANIP_SRC,
15 	NF_NAT_MANIP_DST
16 };
17 
18 /* SRC manip occurs POST_ROUTING or LOCAL_IN */
19 #define HOOK2MANIP(hooknum) ((hooknum) != NF_INET_POST_ROUTING && \
20 			     (hooknum) != NF_INET_LOCAL_IN)
21 
22 /* per conntrack: nat application helper private data */
23 union nf_conntrack_nat_help {
24 	/* insert nat helper private data here */
25 #if IS_ENABLED(CONFIG_NF_NAT_PPTP)
26 	struct nf_nat_pptp nat_pptp_info;
27 #endif
28 };
29 
30 /* The structure embedded in the conntrack structure. */
31 struct nf_conn_nat {
32 	union nf_conntrack_nat_help help;
33 #if IS_ENABLED(CONFIG_NF_NAT_MASQUERADE)
34 	int masq_index;
35 #endif
36 };
37 
38 /* Set up the info structure to map into this range. */
39 unsigned int nf_nat_setup_info(struct nf_conn *ct,
40 			       const struct nf_nat_range2 *range,
41 			       enum nf_nat_manip_type maniptype);
42 
43 extern unsigned int nf_nat_alloc_null_binding(struct nf_conn *ct,
44 					      unsigned int hooknum);
45 
46 struct nf_conn_nat *nf_ct_nat_ext_add(struct nf_conn *ct);
47 
nfct_nat(const struct nf_conn * ct)48 static inline struct nf_conn_nat *nfct_nat(const struct nf_conn *ct)
49 {
50 #if IS_ENABLED(CONFIG_NF_NAT)
51 	return nf_ct_ext_find(ct, NF_CT_EXT_NAT);
52 #else
53 	return NULL;
54 #endif
55 }
56 
nf_nat_oif_changed(unsigned int hooknum,enum ip_conntrack_info ctinfo,struct nf_conn_nat * nat,const struct net_device * out)57 static inline bool nf_nat_oif_changed(unsigned int hooknum,
58 				      enum ip_conntrack_info ctinfo,
59 				      struct nf_conn_nat *nat,
60 				      const struct net_device *out)
61 {
62 #if IS_ENABLED(CONFIG_NF_NAT_MASQUERADE)
63 	return nat && nat->masq_index && hooknum == NF_INET_POST_ROUTING &&
64 	       CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL &&
65 	       nat->masq_index != out->ifindex;
66 #else
67 	return false;
68 #endif
69 }
70 
71 int nf_nat_register_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops,
72 		       const struct nf_hook_ops *nat_ops, unsigned int ops_count);
73 void nf_nat_unregister_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops,
74 			  unsigned int ops_count);
75 
76 unsigned int nf_nat_packet(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
77 			   unsigned int hooknum, struct sk_buff *skb);
78 
79 unsigned int nf_nat_manip_pkt(struct sk_buff *skb, struct nf_conn *ct,
80 			      enum nf_nat_manip_type mtype,
81 			      enum ip_conntrack_dir dir);
82 void nf_nat_csum_recalc(struct sk_buff *skb,
83 			u8 nfproto, u8 proto, void *data, __sum16 *check,
84 			int datalen, int oldlen);
85 
86 int nf_nat_icmp_reply_translation(struct sk_buff *skb, struct nf_conn *ct,
87 				  enum ip_conntrack_info ctinfo,
88 				  unsigned int hooknum);
89 
90 int nf_nat_icmpv6_reply_translation(struct sk_buff *skb, struct nf_conn *ct,
91 				    enum ip_conntrack_info ctinfo,
92 				    unsigned int hooknum, unsigned int hdrlen);
93 
94 int nf_nat_ipv4_register_fn(struct net *net, const struct nf_hook_ops *ops);
95 void nf_nat_ipv4_unregister_fn(struct net *net, const struct nf_hook_ops *ops);
96 
97 int nf_nat_ipv6_register_fn(struct net *net, const struct nf_hook_ops *ops);
98 void nf_nat_ipv6_unregister_fn(struct net *net, const struct nf_hook_ops *ops);
99 
100 int nf_nat_inet_register_fn(struct net *net, const struct nf_hook_ops *ops);
101 void nf_nat_inet_unregister_fn(struct net *net, const struct nf_hook_ops *ops);
102 
103 unsigned int
104 nf_nat_inet_fn(void *priv, struct sk_buff *skb,
105 	       const struct nf_hook_state *state);
106 
nf_nat_initialized(const struct nf_conn * ct,enum nf_nat_manip_type manip)107 static inline int nf_nat_initialized(const struct nf_conn *ct,
108 				     enum nf_nat_manip_type manip)
109 {
110 	if (manip == NF_NAT_MANIP_SRC)
111 		return ct->status & IPS_SRC_NAT_DONE;
112 	else
113 		return ct->status & IPS_DST_NAT_DONE;
114 }
115 #endif
116