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
21struct em_ipt_match {
22	const struct xt_match *match;
23	u32 hook;
24	u8 nfproto;
25	u8 match_data[] __aligned(8);
26};
27
28struct em_ipt_xt_match {
29	char *match_name;
30	int (*validate_match_data)(struct nlattr **tb, u8 mrev);
31};
32
33static 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
42static 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
60static 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
75static 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
85static 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
97static 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
126static 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
179err:
180	kfree(im);
181	module_put(match->me);
182	return ret;
183}
184
185static 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
205static 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
250static 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
270static 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
280static int __init init_em_ipt(void)
281{
282	return tcf_em_register(&em_ipt_ops);
283}
284
285static void __exit exit_em_ipt(void)
286{
287	tcf_em_unregister(&em_ipt_ops);
288}
289
290MODULE_LICENSE("GPL");
291MODULE_AUTHOR("Eyal Birger <eyal.birger@gmail.com>");
292MODULE_DESCRIPTION("TC extended match for IPtables matches");
293
294module_init(init_em_ipt);
295module_exit(exit_em_ipt);
296
297MODULE_ALIAS_TCF_EMATCH(TCF_EM_IPT);
298