1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * net/sched/em_ipt.c IPtables matches Ematch
4 *
5 * (c) 2018 Eyal Birger <eyal.birger@gmail.com>
6 */
7
8 #include <linux/gfp.h>
9 #include <linux/module.h>
10 #include <linux/types.h>
11 #include <linux/kernel.h>
12 #include <linux/string.h>
13 #include <linux/skbuff.h>
14 #include <linux/tc_ematch/tc_em_ipt.h>
15 #include <linux/netfilter.h>
16 #include <linux/netfilter/x_tables.h>
17 #include <linux/netfilter_ipv4/ip_tables.h>
18 #include <linux/netfilter_ipv6/ip6_tables.h>
19 #include <net/pkt_cls.h>
20
21 struct em_ipt_match {
22 const struct xt_match *match;
23 u32 hook;
24 u8 nfproto;
25 u8 match_data[] __aligned(8);
26 };
27
28 struct em_ipt_xt_match {
29 char *match_name;
30 int (*validate_match_data)(struct nlattr **tb, u8 mrev);
31 };
32
33 static const struct nla_policy em_ipt_policy[TCA_EM_IPT_MAX + 1] = {
34 [TCA_EM_IPT_MATCH_NAME] = { .type = NLA_STRING,
35 .len = XT_EXTENSION_MAXNAMELEN },
36 [TCA_EM_IPT_MATCH_REVISION] = { .type = NLA_U8 },
37 [TCA_EM_IPT_HOOK] = { .type = NLA_U32 },
38 [TCA_EM_IPT_NFPROTO] = { .type = NLA_U8 },
39 [TCA_EM_IPT_MATCH_DATA] = { .type = NLA_UNSPEC },
40 };
41
42 static int check_match(struct net *net, struct em_ipt_match *im, int mdata_len)
43 {
44 struct xt_mtchk_param mtpar = {};
45 union {
46 struct ipt_entry e4;
47 struct ip6t_entry e6;
48 } e = {};
49
50 mtpar.net = net;
51 mtpar.table = "filter";
52 mtpar.hook_mask = 1 << im->hook;
53 mtpar.family = im->match->family;
54 mtpar.match = im->match;
55 mtpar.entryinfo = &e;
56 mtpar.matchinfo = (void *)im->match_data;
57 return xt_check_match(&mtpar, mdata_len, 0, 0);
58 }
59
60 static int policy_validate_match_data(struct nlattr **tb, u8 mrev)
61 {
62 if (mrev != 0) {
63 pr_err("only policy match revision 0 supported");
64 return -EINVAL;
65 }
66
67 if (nla_get_u32(tb[TCA_EM_IPT_HOOK]) != NF_INET_PRE_ROUTING) {
68 pr_err("policy can only be matched on NF_INET_PRE_ROUTING");
69 return -EINVAL;
70 }
71
72 return 0;
73 }
74
75 static int addrtype_validate_match_data(struct nlattr **tb, u8 mrev)
76 {
77 if (mrev != 1) {
78 pr_err("only addrtype match revision 1 supported");
79 return -EINVAL;
80 }
81
82 return 0;
83 }
84
85 static const struct em_ipt_xt_match em_ipt_xt_matches[] = {
86 {
87 .match_name = "policy",
88 .validate_match_data = policy_validate_match_data
89 },
90 {
91 .match_name = "addrtype",
92 .validate_match_data = addrtype_validate_match_data
93 },
94 {}
95 };
96
97 static struct xt_match *get_xt_match(struct nlattr **tb)
98 {
99 const struct em_ipt_xt_match *m;
100 struct nlattr *mname_attr;
101 u8 nfproto, mrev = 0;
102 int ret;
103
104 mname_attr = tb[TCA_EM_IPT_MATCH_NAME];
105 for (m = em_ipt_xt_matches; m->match_name; m++) {
106 if (!nla_strcmp(mname_attr, m->match_name))
107 break;
108 }
109
110 if (!m->match_name) {
111 pr_err("Unsupported xt match");
112 return ERR_PTR(-EINVAL);
113 }
114
115 if (tb[TCA_EM_IPT_MATCH_REVISION])
116 mrev = nla_get_u8(tb[TCA_EM_IPT_MATCH_REVISION]);
117
118 ret = m->validate_match_data(tb, mrev);
119 if (ret < 0)
120 return ERR_PTR(ret);
121
122 nfproto = nla_get_u8(tb[TCA_EM_IPT_NFPROTO]);
123 return xt_request_find_match(nfproto, m->match_name, mrev);
124 }
125
126 static int em_ipt_change(struct net *net, void *data, int data_len,
127 struct tcf_ematch *em)
128 {
129 struct nlattr *tb[TCA_EM_IPT_MAX + 1];
130 struct em_ipt_match *im = NULL;
131 struct xt_match *match;
132 int mdata_len, ret;
133 u8 nfproto;
134
135 ret = nla_parse_deprecated(tb, TCA_EM_IPT_MAX, data, data_len,
136 em_ipt_policy, NULL);
137 if (ret < 0)
138 return ret;
139
140 if (!tb[TCA_EM_IPT_HOOK] || !tb[TCA_EM_IPT_MATCH_NAME] ||
141 !tb[TCA_EM_IPT_MATCH_DATA] || !tb[TCA_EM_IPT_NFPROTO])
142 return -EINVAL;
143
144 nfproto = nla_get_u8(tb[TCA_EM_IPT_NFPROTO]);
145 switch (nfproto) {
146 case NFPROTO_IPV4:
147 case NFPROTO_IPV6:
148 break;
149 default:
150 return -EINVAL;
151 }
152
153 match = get_xt_match(tb);
154 if (IS_ERR(match)) {
155 pr_err("unable to load match\n");
156 return PTR_ERR(match);
157 }
158
159 mdata_len = XT_ALIGN(nla_len(tb[TCA_EM_IPT_MATCH_DATA]));
160 im = kzalloc(sizeof(*im) + mdata_len, GFP_KERNEL);
161 if (!im) {
162 ret = -ENOMEM;
163 goto err;
164 }
165
166 im->match = match;
167 im->hook = nla_get_u32(tb[TCA_EM_IPT_HOOK]);
168 im->nfproto = nfproto;
169 nla_memcpy(im->match_data, tb[TCA_EM_IPT_MATCH_DATA], mdata_len);
170
171 ret = check_match(net, im, mdata_len);
172 if (ret)
173 goto err;
174
175 em->datalen = sizeof(*im) + mdata_len;
176 em->data = (unsigned long)im;
177 return 0;
178
179 err:
180 kfree(im);
181 module_put(match->me);
182 return ret;
183 }
184
185 static void em_ipt_destroy(struct tcf_ematch *em)
186 {
187 struct em_ipt_match *im = (void *)em->data;
188
189 if (!im)
190 return;
191
192 if (im->match->destroy) {
193 struct xt_mtdtor_param par = {
194 .net = em->net,
195 .match = im->match,
196 .matchinfo = im->match_data,
197 .family = im->match->family
198 };
199 im->match->destroy(&par);
200 }
201 module_put(im->match->me);
202 kfree(im);
203 }
204
205 static int em_ipt_match(struct sk_buff *skb, struct tcf_ematch *em,
206 struct tcf_pkt_info *info)
207 {
208 const struct em_ipt_match *im = (const void *)em->data;
209 struct xt_action_param acpar = {};
210 struct net_device *indev = NULL;
211 u8 nfproto = im->match->family;
212 struct nf_hook_state state;
213 int ret;
214
215 switch (skb_protocol(skb, true)) {
216 case htons(ETH_P_IP):
217 if (!pskb_network_may_pull(skb, sizeof(struct iphdr)))
218 return 0;
219 if (nfproto == NFPROTO_UNSPEC)
220 nfproto = NFPROTO_IPV4;
221 break;
222 case htons(ETH_P_IPV6):
223 if (!pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))
224 return 0;
225 if (nfproto == NFPROTO_UNSPEC)
226 nfproto = NFPROTO_IPV6;
227 break;
228 default:
229 return 0;
230 }
231
232 rcu_read_lock();
233
234 if (skb->skb_iif)
235 indev = dev_get_by_index_rcu(em->net, skb->skb_iif);
236
237 nf_hook_state_init(&state, im->hook, nfproto,
238 indev ?: skb->dev, skb->dev, NULL, em->net, NULL);
239
240 acpar.match = im->match;
241 acpar.matchinfo = im->match_data;
242 acpar.state = &state;
243
244 ret = im->match->match(skb, &acpar);
245
246 rcu_read_unlock();
247 return ret;
248 }
249
250 static int em_ipt_dump(struct sk_buff *skb, struct tcf_ematch *em)
251 {
252 struct em_ipt_match *im = (void *)em->data;
253
254 if (nla_put_string(skb, TCA_EM_IPT_MATCH_NAME, im->match->name) < 0)
255 return -EMSGSIZE;
256 if (nla_put_u32(skb, TCA_EM_IPT_HOOK, im->hook) < 0)
257 return -EMSGSIZE;
258 if (nla_put_u8(skb, TCA_EM_IPT_MATCH_REVISION, im->match->revision) < 0)
259 return -EMSGSIZE;
260 if (nla_put_u8(skb, TCA_EM_IPT_NFPROTO, im->nfproto) < 0)
261 return -EMSGSIZE;
262 if (nla_put(skb, TCA_EM_IPT_MATCH_DATA,
263 im->match->usersize ?: im->match->matchsize,
264 im->match_data) < 0)
265 return -EMSGSIZE;
266
267 return 0;
268 }
269
270 static struct tcf_ematch_ops em_ipt_ops = {
271 .kind = TCF_EM_IPT,
272 .change = em_ipt_change,
273 .destroy = em_ipt_destroy,
274 .match = em_ipt_match,
275 .dump = em_ipt_dump,
276 .owner = THIS_MODULE,
277 .link = LIST_HEAD_INIT(em_ipt_ops.link)
278 };
279
280 static int __init init_em_ipt(void)
281 {
282 return tcf_em_register(&em_ipt_ops);
283 }
284
285 static void __exit exit_em_ipt(void)
286 {
287 tcf_em_unregister(&em_ipt_ops);
288 }
289
290 MODULE_LICENSE("GPL");
291 MODULE_AUTHOR("Eyal Birger <eyal.birger@gmail.com>");
292 MODULE_DESCRIPTION("TC extended match for IPtables matches");
293
294 module_init(init_em_ipt);
295 module_exit(exit_em_ipt);
296
297 MODULE_ALIAS_TCF_EMATCH(TCF_EM_IPT);
298
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