1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * net/sched/act_ipt.c		iptables target interface
4  *
5  *TODO: Add other tables. For now we only support the ipv4 table targets
6  *
7  * Copyright:	Jamal Hadi Salim (2002-13)
8  */
9 
10 #include <linux/types.h>
11 #include <linux/kernel.h>
12 #include <linux/string.h>
13 #include <linux/errno.h>
14 #include <linux/skbuff.h>
15 #include <linux/rtnetlink.h>
16 #include <linux/module.h>
17 #include <linux/init.h>
18 #include <linux/slab.h>
19 #include <net/netlink.h>
20 #include <net/pkt_sched.h>
21 #include <linux/tc_act/tc_ipt.h>
22 #include <net/tc_act/tc_ipt.h>
23 #include <net/tc_wrapper.h>
24 
25 #include <linux/netfilter_ipv4/ip_tables.h>
26 
27 
28 static struct tc_action_ops act_ipt_ops;
29 static struct tc_action_ops act_xt_ops;
30 
ipt_init_target(struct net * net,struct xt_entry_target * t,char * table,unsigned int hook)31 static int ipt_init_target(struct net *net, struct xt_entry_target *t,
32 			   char *table, unsigned int hook)
33 {
34 	struct xt_tgchk_param par;
35 	struct xt_target *target;
36 	struct ipt_entry e = {};
37 	int ret = 0;
38 
39 	target = xt_request_find_target(AF_INET, t->u.user.name,
40 					t->u.user.revision);
41 	if (IS_ERR(target))
42 		return PTR_ERR(target);
43 
44 	t->u.kernel.target = target;
45 	memset(&par, 0, sizeof(par));
46 	par.net       = net;
47 	par.table     = table;
48 	par.entryinfo = &e;
49 	par.target    = target;
50 	par.targinfo  = t->data;
51 	par.hook_mask = hook;
52 	par.family    = NFPROTO_IPV4;
53 
54 	ret = xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
55 	if (ret < 0) {
56 		module_put(t->u.kernel.target->me);
57 		return ret;
58 	}
59 	return 0;
60 }
61 
ipt_destroy_target(struct xt_entry_target * t,struct net * net)62 static void ipt_destroy_target(struct xt_entry_target *t, struct net *net)
63 {
64 	struct xt_tgdtor_param par = {
65 		.target   = t->u.kernel.target,
66 		.targinfo = t->data,
67 		.family   = NFPROTO_IPV4,
68 		.net      = net,
69 	};
70 	if (par.target->destroy != NULL)
71 		par.target->destroy(&par);
72 	module_put(par.target->me);
73 }
74 
tcf_ipt_release(struct tc_action * a)75 static void tcf_ipt_release(struct tc_action *a)
76 {
77 	struct tcf_ipt *ipt = to_ipt(a);
78 
79 	if (ipt->tcfi_t) {
80 		ipt_destroy_target(ipt->tcfi_t, a->idrinfo->net);
81 		kfree(ipt->tcfi_t);
82 	}
83 	kfree(ipt->tcfi_tname);
84 }
85 
86 static const struct nla_policy ipt_policy[TCA_IPT_MAX + 1] = {
87 	[TCA_IPT_TABLE]	= { .type = NLA_STRING, .len = IFNAMSIZ },
88 	[TCA_IPT_HOOK]	= { .type = NLA_U32 },
89 	[TCA_IPT_INDEX]	= { .type = NLA_U32 },
90 	[TCA_IPT_TARG]	= { .len = sizeof(struct xt_entry_target) },
91 };
92 
__tcf_ipt_init(struct net * net,unsigned int id,struct nlattr * nla,struct nlattr * est,struct tc_action ** a,const struct tc_action_ops * ops,struct tcf_proto * tp,u32 flags)93 static int __tcf_ipt_init(struct net *net, unsigned int id, struct nlattr *nla,
94 			  struct nlattr *est, struct tc_action **a,
95 			  const struct tc_action_ops *ops,
96 			  struct tcf_proto *tp, u32 flags)
97 {
98 	struct tc_action_net *tn = net_generic(net, id);
99 	bool bind = flags & TCA_ACT_FLAGS_BIND;
100 	struct nlattr *tb[TCA_IPT_MAX + 1];
101 	struct tcf_ipt *ipt;
102 	struct xt_entry_target *td, *t;
103 	char *tname;
104 	bool exists = false;
105 	int ret = 0, err;
106 	u32 hook = 0;
107 	u32 index = 0;
108 
109 	if (nla == NULL)
110 		return -EINVAL;
111 
112 	err = nla_parse_nested_deprecated(tb, TCA_IPT_MAX, nla, ipt_policy,
113 					  NULL);
114 	if (err < 0)
115 		return err;
116 
117 	if (tb[TCA_IPT_INDEX] != NULL)
118 		index = nla_get_u32(tb[TCA_IPT_INDEX]);
119 
120 	err = tcf_idr_check_alloc(tn, &index, a, bind);
121 	if (err < 0)
122 		return err;
123 	exists = err;
124 	if (exists && bind)
125 		return 0;
126 
127 	if (tb[TCA_IPT_HOOK] == NULL || tb[TCA_IPT_TARG] == NULL) {
128 		if (exists)
129 			tcf_idr_release(*a, bind);
130 		else
131 			tcf_idr_cleanup(tn, index);
132 		return -EINVAL;
133 	}
134 
135 	td = (struct xt_entry_target *)nla_data(tb[TCA_IPT_TARG]);
136 	if (nla_len(tb[TCA_IPT_TARG]) != td->u.target_size) {
137 		if (exists)
138 			tcf_idr_release(*a, bind);
139 		else
140 			tcf_idr_cleanup(tn, index);
141 		return -EINVAL;
142 	}
143 
144 	if (!exists) {
145 		ret = tcf_idr_create(tn, index, est, a, ops, bind,
146 				     false, flags);
147 		if (ret) {
148 			tcf_idr_cleanup(tn, index);
149 			return ret;
150 		}
151 		ret = ACT_P_CREATED;
152 	} else {
153 		if (bind)/* dont override defaults */
154 			return 0;
155 
156 		if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
157 			tcf_idr_release(*a, bind);
158 			return -EEXIST;
159 		}
160 	}
161 	hook = nla_get_u32(tb[TCA_IPT_HOOK]);
162 
163 	err = -ENOMEM;
164 	tname = kmalloc(IFNAMSIZ, GFP_KERNEL);
165 	if (unlikely(!tname))
166 		goto err1;
167 	if (tb[TCA_IPT_TABLE] == NULL ||
168 	    nla_strscpy(tname, tb[TCA_IPT_TABLE], IFNAMSIZ) >= IFNAMSIZ)
169 		strcpy(tname, "mangle");
170 
171 	t = kmemdup(td, td->u.target_size, GFP_KERNEL);
172 	if (unlikely(!t))
173 		goto err2;
174 
175 	err = ipt_init_target(net, t, tname, hook);
176 	if (err < 0)
177 		goto err3;
178 
179 	ipt = to_ipt(*a);
180 
181 	spin_lock_bh(&ipt->tcf_lock);
182 	if (ret != ACT_P_CREATED) {
183 		ipt_destroy_target(ipt->tcfi_t, net);
184 		kfree(ipt->tcfi_tname);
185 		kfree(ipt->tcfi_t);
186 	}
187 	ipt->tcfi_tname = tname;
188 	ipt->tcfi_t     = t;
189 	ipt->tcfi_hook  = hook;
190 	spin_unlock_bh(&ipt->tcf_lock);
191 	return ret;
192 
193 err3:
194 	kfree(t);
195 err2:
196 	kfree(tname);
197 err1:
198 	tcf_idr_release(*a, bind);
199 	return err;
200 }
201 
tcf_ipt_init(struct net * net,struct nlattr * nla,struct nlattr * est,struct tc_action ** a,struct tcf_proto * tp,u32 flags,struct netlink_ext_ack * extack)202 static int tcf_ipt_init(struct net *net, struct nlattr *nla,
203 			struct nlattr *est, struct tc_action **a,
204 			struct tcf_proto *tp,
205 			u32 flags, struct netlink_ext_ack *extack)
206 {
207 	return __tcf_ipt_init(net, act_ipt_ops.net_id, nla, est,
208 			      a, &act_ipt_ops, tp, flags);
209 }
210 
tcf_xt_init(struct net * net,struct nlattr * nla,struct nlattr * est,struct tc_action ** a,struct tcf_proto * tp,u32 flags,struct netlink_ext_ack * extack)211 static int tcf_xt_init(struct net *net, struct nlattr *nla,
212 		       struct nlattr *est, struct tc_action **a,
213 		       struct tcf_proto *tp,
214 		       u32 flags, struct netlink_ext_ack *extack)
215 {
216 	return __tcf_ipt_init(net, act_xt_ops.net_id, nla, est,
217 			      a, &act_xt_ops, tp, flags);
218 }
219 
tcf_ipt_act(struct sk_buff * skb,const struct tc_action * a,struct tcf_result * res)220 TC_INDIRECT_SCOPE int tcf_ipt_act(struct sk_buff *skb,
221 				  const struct tc_action *a,
222 				  struct tcf_result *res)
223 {
224 	int ret = 0, result = 0;
225 	struct tcf_ipt *ipt = to_ipt(a);
226 	struct xt_action_param par;
227 	struct nf_hook_state state = {
228 		.net	= dev_net(skb->dev),
229 		.in	= skb->dev,
230 		.hook	= ipt->tcfi_hook,
231 		.pf	= NFPROTO_IPV4,
232 	};
233 
234 	if (skb_unclone(skb, GFP_ATOMIC))
235 		return TC_ACT_UNSPEC;
236 
237 	spin_lock(&ipt->tcf_lock);
238 
239 	tcf_lastuse_update(&ipt->tcf_tm);
240 	bstats_update(&ipt->tcf_bstats, skb);
241 
242 	/* yes, we have to worry about both in and out dev
243 	 * worry later - danger - this API seems to have changed
244 	 * from earlier kernels
245 	 */
246 	par.state    = &state;
247 	par.target   = ipt->tcfi_t->u.kernel.target;
248 	par.targinfo = ipt->tcfi_t->data;
249 	ret = par.target->target(skb, &par);
250 
251 	switch (ret) {
252 	case NF_ACCEPT:
253 		result = TC_ACT_OK;
254 		break;
255 	case NF_DROP:
256 		result = TC_ACT_SHOT;
257 		ipt->tcf_qstats.drops++;
258 		break;
259 	case XT_CONTINUE:
260 		result = TC_ACT_PIPE;
261 		break;
262 	default:
263 		net_notice_ratelimited("tc filter: Bogus netfilter code %d assume ACCEPT\n",
264 				       ret);
265 		result = TC_ACT_OK;
266 		break;
267 	}
268 	spin_unlock(&ipt->tcf_lock);
269 	return result;
270 
271 }
272 
tcf_ipt_dump(struct sk_buff * skb,struct tc_action * a,int bind,int ref)273 static int tcf_ipt_dump(struct sk_buff *skb, struct tc_action *a, int bind,
274 			int ref)
275 {
276 	unsigned char *b = skb_tail_pointer(skb);
277 	struct tcf_ipt *ipt = to_ipt(a);
278 	struct xt_entry_target *t;
279 	struct tcf_t tm;
280 	struct tc_cnt c;
281 
282 	/* for simple targets kernel size == user size
283 	 * user name = target name
284 	 * for foolproof you need to not assume this
285 	 */
286 
287 	spin_lock_bh(&ipt->tcf_lock);
288 	t = kmemdup(ipt->tcfi_t, ipt->tcfi_t->u.user.target_size, GFP_ATOMIC);
289 	if (unlikely(!t))
290 		goto nla_put_failure;
291 
292 	c.bindcnt = atomic_read(&ipt->tcf_bindcnt) - bind;
293 	c.refcnt = refcount_read(&ipt->tcf_refcnt) - ref;
294 	strcpy(t->u.user.name, ipt->tcfi_t->u.kernel.target->name);
295 
296 	if (nla_put(skb, TCA_IPT_TARG, ipt->tcfi_t->u.user.target_size, t) ||
297 	    nla_put_u32(skb, TCA_IPT_INDEX, ipt->tcf_index) ||
298 	    nla_put_u32(skb, TCA_IPT_HOOK, ipt->tcfi_hook) ||
299 	    nla_put(skb, TCA_IPT_CNT, sizeof(struct tc_cnt), &c) ||
300 	    nla_put_string(skb, TCA_IPT_TABLE, ipt->tcfi_tname))
301 		goto nla_put_failure;
302 
303 	tcf_tm_dump(&tm, &ipt->tcf_tm);
304 	if (nla_put_64bit(skb, TCA_IPT_TM, sizeof(tm), &tm, TCA_IPT_PAD))
305 		goto nla_put_failure;
306 
307 	spin_unlock_bh(&ipt->tcf_lock);
308 	kfree(t);
309 	return skb->len;
310 
311 nla_put_failure:
312 	spin_unlock_bh(&ipt->tcf_lock);
313 	nlmsg_trim(skb, b);
314 	kfree(t);
315 	return -1;
316 }
317 
318 static struct tc_action_ops act_ipt_ops = {
319 	.kind		=	"ipt",
320 	.id		=	TCA_ID_IPT,
321 	.owner		=	THIS_MODULE,
322 	.act		=	tcf_ipt_act,
323 	.dump		=	tcf_ipt_dump,
324 	.cleanup	=	tcf_ipt_release,
325 	.init		=	tcf_ipt_init,
326 	.size		=	sizeof(struct tcf_ipt),
327 };
328 
ipt_init_net(struct net * net)329 static __net_init int ipt_init_net(struct net *net)
330 {
331 	struct tc_action_net *tn = net_generic(net, act_ipt_ops.net_id);
332 
333 	return tc_action_net_init(net, tn, &act_ipt_ops);
334 }
335 
ipt_exit_net(struct list_head * net_list)336 static void __net_exit ipt_exit_net(struct list_head *net_list)
337 {
338 	tc_action_net_exit(net_list, act_ipt_ops.net_id);
339 }
340 
341 static struct pernet_operations ipt_net_ops = {
342 	.init = ipt_init_net,
343 	.exit_batch = ipt_exit_net,
344 	.id   = &act_ipt_ops.net_id,
345 	.size = sizeof(struct tc_action_net),
346 };
347 
348 static struct tc_action_ops act_xt_ops = {
349 	.kind		=	"xt",
350 	.id		=	TCA_ID_XT,
351 	.owner		=	THIS_MODULE,
352 	.act		=	tcf_ipt_act,
353 	.dump		=	tcf_ipt_dump,
354 	.cleanup	=	tcf_ipt_release,
355 	.init		=	tcf_xt_init,
356 	.size		=	sizeof(struct tcf_ipt),
357 };
358 
xt_init_net(struct net * net)359 static __net_init int xt_init_net(struct net *net)
360 {
361 	struct tc_action_net *tn = net_generic(net, act_xt_ops.net_id);
362 
363 	return tc_action_net_init(net, tn, &act_xt_ops);
364 }
365 
xt_exit_net(struct list_head * net_list)366 static void __net_exit xt_exit_net(struct list_head *net_list)
367 {
368 	tc_action_net_exit(net_list, act_xt_ops.net_id);
369 }
370 
371 static struct pernet_operations xt_net_ops = {
372 	.init = xt_init_net,
373 	.exit_batch = xt_exit_net,
374 	.id   = &act_xt_ops.net_id,
375 	.size = sizeof(struct tc_action_net),
376 };
377 
378 MODULE_AUTHOR("Jamal Hadi Salim(2002-13)");
379 MODULE_DESCRIPTION("Iptables target actions");
380 MODULE_LICENSE("GPL");
381 MODULE_ALIAS("act_xt");
382 
ipt_init_module(void)383 static int __init ipt_init_module(void)
384 {
385 	int ret1, ret2;
386 
387 	ret1 = tcf_register_action(&act_xt_ops, &xt_net_ops);
388 	if (ret1 < 0)
389 		pr_err("Failed to load xt action\n");
390 
391 	ret2 = tcf_register_action(&act_ipt_ops, &ipt_net_ops);
392 	if (ret2 < 0)
393 		pr_err("Failed to load ipt action\n");
394 
395 	if (ret1 < 0 && ret2 < 0) {
396 		return ret1;
397 	} else
398 		return 0;
399 }
400 
ipt_cleanup_module(void)401 static void __exit ipt_cleanup_module(void)
402 {
403 	tcf_unregister_action(&act_ipt_ops, &ipt_net_ops);
404 	tcf_unregister_action(&act_xt_ops, &xt_net_ops);
405 }
406 
407 module_init(ipt_init_module);
408 module_exit(ipt_cleanup_module);
409