1 /* (C) 1999-2001 Paul `Rusty' Russell
2 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
3 * (C) 2008 Patrick McHardy <kaber@trash.net>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 */
9
10 #include <linux/types.h>
11 #include <linux/random.h>
12 #include <linux/netfilter.h>
13 #include <linux/export.h>
14
15 #include <net/netfilter/nf_nat.h>
16 #include <net/netfilter/nf_nat_core.h>
17 #include <net/netfilter/nf_nat_l3proto.h>
18 #include <net/netfilter/nf_nat_l4proto.h>
19
nf_nat_l4proto_in_range(const struct nf_conntrack_tuple * tuple,enum nf_nat_manip_type maniptype,const union nf_conntrack_man_proto * min,const union nf_conntrack_man_proto * max)20 bool nf_nat_l4proto_in_range(const struct nf_conntrack_tuple *tuple,
21 enum nf_nat_manip_type maniptype,
22 const union nf_conntrack_man_proto *min,
23 const union nf_conntrack_man_proto *max)
24 {
25 __be16 port;
26
27 if (maniptype == NF_NAT_MANIP_SRC)
28 port = tuple->src.u.all;
29 else
30 port = tuple->dst.u.all;
31
32 return ntohs(port) >= ntohs(min->all) &&
33 ntohs(port) <= ntohs(max->all);
34 }
35 EXPORT_SYMBOL_GPL(nf_nat_l4proto_in_range);
36
nf_nat_l4proto_unique_tuple(const struct nf_nat_l3proto * l3proto,struct nf_conntrack_tuple * tuple,const struct nf_nat_range2 * range,enum nf_nat_manip_type maniptype,const struct nf_conn * ct,u16 * rover)37 void nf_nat_l4proto_unique_tuple(const struct nf_nat_l3proto *l3proto,
38 struct nf_conntrack_tuple *tuple,
39 const struct nf_nat_range2 *range,
40 enum nf_nat_manip_type maniptype,
41 const struct nf_conn *ct,
42 u16 *rover)
43 {
44 unsigned int range_size, min, max, i;
45 __be16 *portptr;
46 u_int16_t off;
47
48 if (maniptype == NF_NAT_MANIP_SRC)
49 portptr = &tuple->src.u.all;
50 else
51 portptr = &tuple->dst.u.all;
52
53 /* If no range specified... */
54 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
55 /* If it's dst rewrite, can't change port */
56 if (maniptype == NF_NAT_MANIP_DST)
57 return;
58
59 if (ntohs(*portptr) < 1024) {
60 /* Loose convention: >> 512 is credential passing */
61 if (ntohs(*portptr) < 512) {
62 min = 1;
63 range_size = 511 - min + 1;
64 } else {
65 min = 600;
66 range_size = 1023 - min + 1;
67 }
68 } else {
69 min = 1024;
70 range_size = 65535 - 1024 + 1;
71 }
72 } else {
73 min = ntohs(range->min_proto.all);
74 max = ntohs(range->max_proto.all);
75 if (unlikely(max < min))
76 swap(max, min);
77 range_size = max - min + 1;
78 }
79
80 if (range->flags & NF_NAT_RANGE_PROTO_RANDOM) {
81 off = l3proto->secure_port(tuple, maniptype == NF_NAT_MANIP_SRC
82 ? tuple->dst.u.all
83 : tuple->src.u.all);
84 } else if (range->flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY) {
85 off = prandom_u32();
86 } else if (range->flags & NF_NAT_RANGE_PROTO_OFFSET) {
87 off = (ntohs(*portptr) - ntohs(range->base_proto.all));
88 } else {
89 off = *rover;
90 }
91
92 for (i = 0; ; ++off) {
93 *portptr = htons(min + off % range_size);
94 if (++i != range_size && nf_nat_used_tuple(tuple, ct))
95 continue;
96 if (!(range->flags & (NF_NAT_RANGE_PROTO_RANDOM_ALL|
97 NF_NAT_RANGE_PROTO_OFFSET)))
98 *rover = off;
99 return;
100 }
101 }
102 EXPORT_SYMBOL_GPL(nf_nat_l4proto_unique_tuple);
103
104 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
nf_nat_l4proto_nlattr_to_range(struct nlattr * tb[],struct nf_nat_range2 * range)105 int nf_nat_l4proto_nlattr_to_range(struct nlattr *tb[],
106 struct nf_nat_range2 *range)
107 {
108 if (tb[CTA_PROTONAT_PORT_MIN]) {
109 range->min_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MIN]);
110 range->max_proto.all = range->min_proto.all;
111 range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
112 }
113 if (tb[CTA_PROTONAT_PORT_MAX]) {
114 range->max_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MAX]);
115 range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
116 }
117 return 0;
118 }
119 EXPORT_SYMBOL_GPL(nf_nat_l4proto_nlattr_to_range);
120 #endif
121
