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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * xt_connmark - Netfilter module to operate on connection marks
4 *
5 * Copyright (C) 2002,2004 MARA Systems AB <https://www.marasystems.com>
6 * by Henrik Nordstrom <[email protected]>
7 * Copyright © CC Computer Consultants GmbH, 2007 - 2008
8 * Jan Engelhardt <[email protected]>
9 */
10
11#include <linux/module.h>
12#include <linux/skbuff.h>
13#include <net/netfilter/nf_conntrack.h>
14#include <net/netfilter/nf_conntrack_ecache.h>
15#include <linux/netfilter/x_tables.h>
16#include <linux/netfilter/xt_connmark.h>
17
18MODULE_AUTHOR("Henrik Nordstrom <[email protected]>");
19MODULE_DESCRIPTION("Xtables: connection mark operations");
20MODULE_LICENSE("GPL");
21MODULE_ALIAS("ipt_CONNMARK");
22MODULE_ALIAS("ip6t_CONNMARK");
23MODULE_ALIAS("ipt_connmark");
24MODULE_ALIAS("ip6t_connmark");
25
26static unsigned int
27connmark_tg_shift(struct sk_buff *skb, const struct xt_connmark_tginfo2 *info)
28{
29 enum ip_conntrack_info ctinfo;
30 u_int32_t new_targetmark;
31 struct nf_conn *ct;
32 u_int32_t newmark;
33 u_int32_t oldmark;
34
35 ct = nf_ct_get(skb, &ctinfo);
36 if (ct == NULL)
37 return XT_CONTINUE;
38
39 switch (info->mode) {
40 case XT_CONNMARK_SET:
41 oldmark = READ_ONCE(ct->mark);
42 newmark = (oldmark & ~info->ctmask) ^ info->ctmark;
43 if (info->shift_dir == D_SHIFT_RIGHT)
44 newmark >>= info->shift_bits;
45 else
46 newmark <<= info->shift_bits;
47
48 if (READ_ONCE(ct->mark) != newmark) {
49 WRITE_ONCE(ct->mark, newmark);
50 nf_conntrack_event_cache(IPCT_MARK, ct);
51 }
52 break;
53 case XT_CONNMARK_SAVE:
54 new_targetmark = (skb->mark & info->nfmask);
55 if (info->shift_dir == D_SHIFT_RIGHT)
56 new_targetmark >>= info->shift_bits;
57 else
58 new_targetmark <<= info->shift_bits;
59
60 newmark = (READ_ONCE(ct->mark) & ~info->ctmask) ^
61 new_targetmark;
62 if (READ_ONCE(ct->mark) != newmark) {
63 WRITE_ONCE(ct->mark, newmark);
64 nf_conntrack_event_cache(IPCT_MARK, ct);
65 }
66 break;
67 case XT_CONNMARK_RESTORE:
68 new_targetmark = (READ_ONCE(ct->mark) & info->ctmask);
69 if (info->shift_dir == D_SHIFT_RIGHT)
70 new_targetmark >>= info->shift_bits;
71 else
72 new_targetmark <<= info->shift_bits;
73
74 newmark = (skb->mark & ~info->nfmask) ^
75 new_targetmark;
76 skb->mark = newmark;
77 break;
78 }
79 return XT_CONTINUE;
80}
81
82static unsigned int
83connmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
84{
85 const struct xt_connmark_tginfo1 *info = par->targinfo;
86 const struct xt_connmark_tginfo2 info2 = {
87 .ctmark = info->ctmark,
88 .ctmask = info->ctmask,
89 .nfmask = info->nfmask,
90 .mode = info->mode,
91 };
92
93 return connmark_tg_shift(skb, &info2);
94}
95
96static unsigned int
97connmark_tg_v2(struct sk_buff *skb, const struct xt_action_param *par)
98{
99 const struct xt_connmark_tginfo2 *info = par->targinfo;
100
101 return connmark_tg_shift(skb, info);
102}
103
104static int connmark_tg_check(const struct xt_tgchk_param *par)
105{
106 int ret;
107
108 ret = nf_ct_netns_get(par->net, par->family);
109 if (ret < 0)
110 pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
111 par->family);
112 return ret;
113}
114
115static int connmark_tg_check_v2(const struct xt_tgchk_param *par)
116{
117 const struct xt_connmark_tginfo2 *info = par->targinfo;
118
119 if (info->shift_dir > D_SHIFT_RIGHT || info->shift_bits >= 32)
120 return -EINVAL;
121
122 return connmark_tg_check(par);
123}
124
125static void connmark_tg_destroy(const struct xt_tgdtor_param *par)
126{
127 nf_ct_netns_put(par->net, par->family);
128}
129
130static bool
131connmark_mt(const struct sk_buff *skb, struct xt_action_param *par)
132{
133 const struct xt_connmark_mtinfo1 *info = par->matchinfo;
134 enum ip_conntrack_info ctinfo;
135 const struct nf_conn *ct;
136
137 ct = nf_ct_get(skb, &ctinfo);
138 if (ct == NULL)
139 return false;
140
141 return ((READ_ONCE(ct->mark) & info->mask) == info->mark) ^ info->invert;
142}
143
144static int connmark_mt_check(const struct xt_mtchk_param *par)
145{
146 int ret;
147
148 ret = nf_ct_netns_get(par->net, par->family);
149 if (ret < 0)
150 pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
151 par->family);
152 return ret;
153}
154
155static void connmark_mt_destroy(const struct xt_mtdtor_param *par)
156{
157 nf_ct_netns_put(par->net, par->family);
158}
159
160static struct xt_target connmark_tg_reg[] __read_mostly = {
161 {
162 .name = "CONNMARK",
163 .revision = 1,
164 .family = NFPROTO_IPV4,
165 .checkentry = connmark_tg_check,
166 .target = connmark_tg,
167 .targetsize = sizeof(struct xt_connmark_tginfo1),
168 .destroy = connmark_tg_destroy,
169 .me = THIS_MODULE,
170 },
171 {
172 .name = "CONNMARK",
173 .revision = 2,
174 .family = NFPROTO_IPV4,
175 .checkentry = connmark_tg_check_v2,
176 .target = connmark_tg_v2,
177 .targetsize = sizeof(struct xt_connmark_tginfo2),
178 .destroy = connmark_tg_destroy,
179 .me = THIS_MODULE,
180 },
181#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
182 {
183 .name = "CONNMARK",
184 .revision = 1,
185 .family = NFPROTO_IPV6,
186 .checkentry = connmark_tg_check,
187 .target = connmark_tg,
188 .targetsize = sizeof(struct xt_connmark_tginfo1),
189 .destroy = connmark_tg_destroy,
190 .me = THIS_MODULE,
191 },
192 {
193 .name = "CONNMARK",
194 .revision = 2,
195 .family = NFPROTO_IPV6,
196 .checkentry = connmark_tg_check_v2,
197 .target = connmark_tg_v2,
198 .targetsize = sizeof(struct xt_connmark_tginfo2),
199 .destroy = connmark_tg_destroy,
200 .me = THIS_MODULE,
201 },
202#endif
203};
204
205static struct xt_match connmark_mt_reg __read_mostly = {
206 .name = "connmark",
207 .revision = 1,
208 .family = NFPROTO_UNSPEC,
209 .checkentry = connmark_mt_check,
210 .match = connmark_mt,
211 .matchsize = sizeof(struct xt_connmark_mtinfo1),
212 .destroy = connmark_mt_destroy,
213 .me = THIS_MODULE,
214};
215
216static int __init connmark_mt_init(void)
217{
218 int ret;
219
220 ret = xt_register_targets(connmark_tg_reg,
221 ARRAY_SIZE(connmark_tg_reg));
222 if (ret < 0)
223 return ret;
224 ret = xt_register_match(&connmark_mt_reg);
225 if (ret < 0) {
226 xt_unregister_targets(connmark_tg_reg,
227 ARRAY_SIZE(connmark_tg_reg));
228 return ret;
229 }
230 return 0;
231}
232
233static void __exit connmark_mt_exit(void)
234{
235 xt_unregister_match(&connmark_mt_reg);
236 xt_unregister_targets(connmark_tg_reg, ARRAY_SIZE(connmark_tg_reg));
237}
238
239module_init(connmark_mt_init);
240module_exit(connmark_mt_exit);