xref: /linux/net/sched/act_pedit.c (revision 55223394d56bab42ebac71ba52e0fd8bfdc6fc07) 
1 /*
2  * net/sched/act_pedit.c	Generic packet editor
3  *
4  *		This program is free software; you can redistribute it and/or
5  *		modify it under the terms of the GNU General Public License
6  *		as published by the Free Software Foundation; either version
7  *		2 of the License, or (at your option) any later version.
8  *
9  * Authors:	Jamal Hadi Salim (2002-4)
10  */
11 
12 #include <linux/types.h>
13 #include <linux/kernel.h>
14 #include <linux/string.h>
15 #include <linux/errno.h>
16 #include <linux/skbuff.h>
17 #include <linux/rtnetlink.h>
18 #include <linux/module.h>
19 #include <linux/init.h>
20 #include <linux/slab.h>
21 #include <net/netlink.h>
22 #include <net/pkt_sched.h>
23 #include <linux/tc_act/tc_pedit.h>
24 #include <net/tc_act/tc_pedit.h>
25 #include <uapi/linux/tc_act/tc_pedit.h>
26 #include <net/pkt_cls.h>
27 
28 static unsigned int pedit_net_id;
29 static struct tc_action_ops act_pedit_ops;
30 
31 static const struct nla_policy pedit_policy[TCA_PEDIT_MAX + 1] = {
32 	[TCA_PEDIT_PARMS]	= { .len = sizeof(struct tc_pedit) },
33 	[TCA_PEDIT_KEYS_EX]   = { .type = NLA_NESTED },
34 };
35 
36 static const struct nla_policy pedit_key_ex_policy[TCA_PEDIT_KEY_EX_MAX + 1] = {
37 	[TCA_PEDIT_KEY_EX_HTYPE]  = { .type = NLA_U16 },
38 	[TCA_PEDIT_KEY_EX_CMD]	  = { .type = NLA_U16 },
39 };
40 
41 static struct tcf_pedit_key_ex *tcf_pedit_keys_ex_parse(struct nlattr *nla,
42 							u8 n)
43 {
44 	struct tcf_pedit_key_ex *keys_ex;
45 	struct tcf_pedit_key_ex *k;
46 	const struct nlattr *ka;
47 	int err = -EINVAL;
48 	int rem;
49 
50 	if (!nla || !n)
51 		return NULL;
52 
53 	keys_ex = kcalloc(n, sizeof(*k), GFP_KERNEL);
54 	if (!keys_ex)
55 		return ERR_PTR(-ENOMEM);
56 
57 	k = keys_ex;
58 
59 	nla_for_each_nested(ka, nla, rem) {
60 		struct nlattr *tb[TCA_PEDIT_KEY_EX_MAX + 1];
61 
62 		if (!n) {
63 			err = -EINVAL;
64 			goto err_out;
65 		}
66 		n--;
67 
68 		if (nla_type(ka) != TCA_PEDIT_KEY_EX) {
69 			err = -EINVAL;
70 			goto err_out;
71 		}
72 
73 		err = nla_parse_nested(tb, TCA_PEDIT_KEY_EX_MAX, ka,
74 				       pedit_key_ex_policy, NULL);
75 		if (err)
76 			goto err_out;
77 
78 		if (!tb[TCA_PEDIT_KEY_EX_HTYPE] ||
79 		    !tb[TCA_PEDIT_KEY_EX_CMD]) {
80 			err = -EINVAL;
81 			goto err_out;
82 		}
83 
84 		k->htype = nla_get_u16(tb[TCA_PEDIT_KEY_EX_HTYPE]);
85 		k->cmd = nla_get_u16(tb[TCA_PEDIT_KEY_EX_CMD]);
86 
87 		if (k->htype > TCA_PEDIT_HDR_TYPE_MAX ||
88 		    k->cmd > TCA_PEDIT_CMD_MAX) {
89 			err = -EINVAL;
90 			goto err_out;
91 		}
92 
93 		k++;
94 	}
95 
96 	if (n) {
97 		err = -EINVAL;
98 		goto err_out;
99 	}
100 
101 	return keys_ex;
102 
103 err_out:
104 	kfree(keys_ex);
105 	return ERR_PTR(err);
106 }
107 
108 static int tcf_pedit_key_ex_dump(struct sk_buff *skb,
109 				 struct tcf_pedit_key_ex *keys_ex, int n)
110 {
111 	struct nlattr *keys_start = nla_nest_start(skb, TCA_PEDIT_KEYS_EX);
112 
113 	if (!keys_start)
114 		goto nla_failure;
115 	for (; n > 0; n--) {
116 		struct nlattr *key_start;
117 
118 		key_start = nla_nest_start(skb, TCA_PEDIT_KEY_EX);
119 		if (!key_start)
120 			goto nla_failure;
121 
122 		if (nla_put_u16(skb, TCA_PEDIT_KEY_EX_HTYPE, keys_ex->htype) ||
123 		    nla_put_u16(skb, TCA_PEDIT_KEY_EX_CMD, keys_ex->cmd))
124 			goto nla_failure;
125 
126 		nla_nest_end(skb, key_start);
127 
128 		keys_ex++;
129 	}
130 
131 	nla_nest_end(skb, keys_start);
132 
133 	return 0;
134 nla_failure:
135 	nla_nest_cancel(skb, keys_start);
136 	return -EINVAL;
137 }
138 
139 static int tcf_pedit_init(struct net *net, struct nlattr *nla,
140 			  struct nlattr *est, struct tc_action **a,
141 			  int ovr, int bind, bool rtnl_held,
142 			  struct tcf_proto *tp, struct netlink_ext_ack *extack)
143 {
144 	struct tc_action_net *tn = net_generic(net, pedit_net_id);
145 	struct nlattr *tb[TCA_PEDIT_MAX + 1];
146 	struct tcf_chain *goto_ch = NULL;
147 	struct tc_pedit_key *keys = NULL;
148 	struct tcf_pedit_key_ex *keys_ex;
149 	struct tc_pedit *parm;
150 	struct nlattr *pattr;
151 	struct tcf_pedit *p;
152 	int ret = 0, err;
153 	int ksize;
154 
155 	if (!nla) {
156 		NL_SET_ERR_MSG_MOD(extack, "Pedit requires attributes to be passed");
157 		return -EINVAL;
158 	}
159 
160 	err = nla_parse_nested(tb, TCA_PEDIT_MAX, nla, pedit_policy, NULL);
161 	if (err < 0)
162 		return err;
163 
164 	pattr = tb[TCA_PEDIT_PARMS];
165 	if (!pattr)
166 		pattr = tb[TCA_PEDIT_PARMS_EX];
167 	if (!pattr) {
168 		NL_SET_ERR_MSG_MOD(extack, "Missing required TCA_PEDIT_PARMS or TCA_PEDIT_PARMS_EX pedit attribute");
169 		return -EINVAL;
170 	}
171 
172 	parm = nla_data(pattr);
173 	ksize = parm->nkeys * sizeof(struct tc_pedit_key);
174 	if (nla_len(pattr) < sizeof(*parm) + ksize) {
175 		NL_SET_ERR_MSG_ATTR(extack, pattr, "Length of TCA_PEDIT_PARMS or TCA_PEDIT_PARMS_EX pedit attribute is invalid");
176 		return -EINVAL;
177 	}
178 
179 	keys_ex = tcf_pedit_keys_ex_parse(tb[TCA_PEDIT_KEYS_EX], parm->nkeys);
180 	if (IS_ERR(keys_ex))
181 		return PTR_ERR(keys_ex);
182 
183 	err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
184 	if (!err) {
185 		if (!parm->nkeys) {
186 			tcf_idr_cleanup(tn, parm->index);
187 			NL_SET_ERR_MSG_MOD(extack, "Pedit requires keys to be passed");
188 			ret = -EINVAL;
189 			goto out_free;
190 		}
191 		ret = tcf_idr_create(tn, parm->index, est, a,
192 				     &act_pedit_ops, bind, false);
193 		if (ret) {
194 			tcf_idr_cleanup(tn, parm->index);
195 			goto out_free;
196 		}
197 		ret = ACT_P_CREATED;
198 	} else if (err > 0) {
199 		if (bind)
200 			goto out_free;
201 		if (!ovr) {
202 			ret = -EEXIST;
203 			goto out_release;
204 		}
205 	} else {
206 		ret = err;
207 		goto out_free;
208 	}
209 
210 	err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
211 	if (err < 0) {
212 		ret = err;
213 		goto out_release;
214 	}
215 	p = to_pedit(*a);
216 	spin_lock_bh(&p->tcf_lock);
217 
218 	if (ret == ACT_P_CREATED ||
219 	    (p->tcfp_nkeys && p->tcfp_nkeys != parm->nkeys)) {
220 		keys = kmalloc(ksize, GFP_ATOMIC);
221 		if (!keys) {
222 			spin_unlock_bh(&p->tcf_lock);
223 			ret = -ENOMEM;
224 			goto put_chain;
225 		}
226 		kfree(p->tcfp_keys);
227 		p->tcfp_keys = keys;
228 		p->tcfp_nkeys = parm->nkeys;
229 	}
230 	memcpy(p->tcfp_keys, parm->keys, ksize);
231 
232 	p->tcfp_flags = parm->flags;
233 	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
234 
235 	kfree(p->tcfp_keys_ex);
236 	p->tcfp_keys_ex = keys_ex;
237 
238 	spin_unlock_bh(&p->tcf_lock);
239 	if (goto_ch)
240 		tcf_chain_put_by_act(goto_ch);
241 	if (ret == ACT_P_CREATED)
242 		tcf_idr_insert(tn, *a);
243 	return ret;
244 
245 put_chain:
246 	if (goto_ch)
247 		tcf_chain_put_by_act(goto_ch);
248 out_release:
249 	tcf_idr_release(*a, bind);
250 out_free:
251 	kfree(keys_ex);
252 	return ret;
253 
254 }
255 
256 static void tcf_pedit_cleanup(struct tc_action *a)
257 {
258 	struct tcf_pedit *p = to_pedit(a);
259 	struct tc_pedit_key *keys = p->tcfp_keys;
260 
261 	kfree(keys);
262 	kfree(p->tcfp_keys_ex);
263 }
264 
265 static bool offset_valid(struct sk_buff *skb, int offset)
266 {
267 	if (offset > 0 && offset > skb->len)
268 		return false;
269 
270 	if  (offset < 0 && -offset > skb_headroom(skb))
271 		return false;
272 
273 	return true;
274 }
275 
276 static int pedit_skb_hdr_offset(struct sk_buff *skb,
277 				enum pedit_header_type htype, int *hoffset)
278 {
279 	int ret = -EINVAL;
280 
281 	switch (htype) {
282 	case TCA_PEDIT_KEY_EX_HDR_TYPE_ETH:
283 		if (skb_mac_header_was_set(skb)) {
284 			*hoffset = skb_mac_offset(skb);
285 			ret = 0;
286 		}
287 		break;
288 	case TCA_PEDIT_KEY_EX_HDR_TYPE_NETWORK:
289 	case TCA_PEDIT_KEY_EX_HDR_TYPE_IP4:
290 	case TCA_PEDIT_KEY_EX_HDR_TYPE_IP6:
291 		*hoffset = skb_network_offset(skb);
292 		ret = 0;
293 		break;
294 	case TCA_PEDIT_KEY_EX_HDR_TYPE_TCP:
295 	case TCA_PEDIT_KEY_EX_HDR_TYPE_UDP:
296 		if (skb_transport_header_was_set(skb)) {
297 			*hoffset = skb_transport_offset(skb);
298 			ret = 0;
299 		}
300 		break;
301 	default:
302 		ret = -EINVAL;
303 		break;
304 	}
305 
306 	return ret;
307 }
308 
309 static int tcf_pedit_act(struct sk_buff *skb, const struct tc_action *a,
310 			 struct tcf_result *res)
311 {
312 	struct tcf_pedit *p = to_pedit(a);
313 	int i;
314 
315 	if (skb_unclone(skb, GFP_ATOMIC))
316 		return p->tcf_action;
317 
318 	spin_lock(&p->tcf_lock);
319 
320 	tcf_lastuse_update(&p->tcf_tm);
321 
322 	if (p->tcfp_nkeys > 0) {
323 		struct tc_pedit_key *tkey = p->tcfp_keys;
324 		struct tcf_pedit_key_ex *tkey_ex = p->tcfp_keys_ex;
325 		enum pedit_header_type htype =
326 			TCA_PEDIT_KEY_EX_HDR_TYPE_NETWORK;
327 		enum pedit_cmd cmd = TCA_PEDIT_KEY_EX_CMD_SET;
328 
329 		for (i = p->tcfp_nkeys; i > 0; i--, tkey++) {
330 			u32 *ptr, hdata;
331 			int offset = tkey->off;
332 			int hoffset;
333 			u32 val;
334 			int rc;
335 
336 			if (tkey_ex) {
337 				htype = tkey_ex->htype;
338 				cmd = tkey_ex->cmd;
339 
340 				tkey_ex++;
341 			}
342 
343 			rc = pedit_skb_hdr_offset(skb, htype, &hoffset);
344 			if (rc) {
345 				pr_info("tc action pedit bad header type specified (0x%x)\n",
346 					htype);
347 				goto bad;
348 			}
349 
350 			if (tkey->offmask) {
351 				u8 *d, _d;
352 
353 				if (!offset_valid(skb, hoffset + tkey->at)) {
354 					pr_info("tc action pedit 'at' offset %d out of bounds\n",
355 						hoffset + tkey->at);
356 					goto bad;
357 				}
358 				d = skb_header_pointer(skb, hoffset + tkey->at,
359 						       sizeof(_d), &_d);
360 				if (!d)
361 					goto bad;
362 				offset += (*d & tkey->offmask) >> tkey->shift;
363 			}
364 
365 			if (offset % 4) {
366 				pr_info("tc action pedit offset must be on 32 bit boundaries\n");
367 				goto bad;
368 			}
369 
370 			if (!offset_valid(skb, hoffset + offset)) {
371 				pr_info("tc action pedit offset %d out of bounds\n",
372 					hoffset + offset);
373 				goto bad;
374 			}
375 
376 			ptr = skb_header_pointer(skb, hoffset + offset,
377 						 sizeof(hdata), &hdata);
378 			if (!ptr)
379 				goto bad;
380 			/* just do it, baby */
381 			switch (cmd) {
382 			case TCA_PEDIT_KEY_EX_CMD_SET:
383 				val = tkey->val;
384 				break;
385 			case TCA_PEDIT_KEY_EX_CMD_ADD:
386 				val = (*ptr + tkey->val) & ~tkey->mask;
387 				break;
388 			default:
389 				pr_info("tc action pedit bad command (%d)\n",
390 					cmd);
391 				goto bad;
392 			}
393 
394 			*ptr = ((*ptr & tkey->mask) ^ val);
395 			if (ptr == &hdata)
396 				skb_store_bits(skb, hoffset + offset, ptr, 4);
397 		}
398 
399 		goto done;
400 	} else {
401 		WARN(1, "pedit BUG: index %d\n", p->tcf_index);
402 	}
403 
404 bad:
405 	p->tcf_qstats.overlimits++;
406 done:
407 	bstats_update(&p->tcf_bstats, skb);
408 	spin_unlock(&p->tcf_lock);
409 	return p->tcf_action;
410 }
411 
412 static int tcf_pedit_dump(struct sk_buff *skb, struct tc_action *a,
413 			  int bind, int ref)
414 {
415 	unsigned char *b = skb_tail_pointer(skb);
416 	struct tcf_pedit *p = to_pedit(a);
417 	struct tc_pedit *opt;
418 	struct tcf_t t;
419 	int s;
420 
421 	s = struct_size(opt, keys, p->tcfp_nkeys);
422 
423 	/* netlink spinlocks held above us - must use ATOMIC */
424 	opt = kzalloc(s, GFP_ATOMIC);
425 	if (unlikely(!opt))
426 		return -ENOBUFS;
427 
428 	spin_lock_bh(&p->tcf_lock);
429 	memcpy(opt->keys, p->tcfp_keys,
430 	       p->tcfp_nkeys * sizeof(struct tc_pedit_key));
431 	opt->index = p->tcf_index;
432 	opt->nkeys = p->tcfp_nkeys;
433 	opt->flags = p->tcfp_flags;
434 	opt->action = p->tcf_action;
435 	opt->refcnt = refcount_read(&p->tcf_refcnt) - ref;
436 	opt->bindcnt = atomic_read(&p->tcf_bindcnt) - bind;
437 
438 	if (p->tcfp_keys_ex) {
439 		if (tcf_pedit_key_ex_dump(skb,
440 					  p->tcfp_keys_ex,
441 					  p->tcfp_nkeys))
442 			goto nla_put_failure;
443 
444 		if (nla_put(skb, TCA_PEDIT_PARMS_EX, s, opt))
445 			goto nla_put_failure;
446 	} else {
447 		if (nla_put(skb, TCA_PEDIT_PARMS, s, opt))
448 			goto nla_put_failure;
449 	}
450 
451 	tcf_tm_dump(&t, &p->tcf_tm);
452 	if (nla_put_64bit(skb, TCA_PEDIT_TM, sizeof(t), &t, TCA_PEDIT_PAD))
453 		goto nla_put_failure;
454 	spin_unlock_bh(&p->tcf_lock);
455 
456 	kfree(opt);
457 	return skb->len;
458 
459 nla_put_failure:
460 	spin_unlock_bh(&p->tcf_lock);
461 	nlmsg_trim(skb, b);
462 	kfree(opt);
463 	return -1;
464 }
465 
466 static int tcf_pedit_walker(struct net *net, struct sk_buff *skb,
467 			    struct netlink_callback *cb, int type,
468 			    const struct tc_action_ops *ops,
469 			    struct netlink_ext_ack *extack)
470 {
471 	struct tc_action_net *tn = net_generic(net, pedit_net_id);
472 
473 	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
474 }
475 
476 static int tcf_pedit_search(struct net *net, struct tc_action **a, u32 index)
477 {
478 	struct tc_action_net *tn = net_generic(net, pedit_net_id);
479 
480 	return tcf_idr_search(tn, a, index);
481 }
482 
483 static struct tc_action_ops act_pedit_ops = {
484 	.kind		=	"pedit",
485 	.id		=	TCA_ID_PEDIT,
486 	.owner		=	THIS_MODULE,
487 	.act		=	tcf_pedit_act,
488 	.dump		=	tcf_pedit_dump,
489 	.cleanup	=	tcf_pedit_cleanup,
490 	.init		=	tcf_pedit_init,
491 	.walk		=	tcf_pedit_walker,
492 	.lookup		=	tcf_pedit_search,
493 	.size		=	sizeof(struct tcf_pedit),
494 };
495 
496 static __net_init int pedit_init_net(struct net *net)
497 {
498 	struct tc_action_net *tn = net_generic(net, pedit_net_id);
499 
500 	return tc_action_net_init(tn, &act_pedit_ops);
501 }
502 
503 static void __net_exit pedit_exit_net(struct list_head *net_list)
504 {
505 	tc_action_net_exit(net_list, pedit_net_id);
506 }
507 
508 static struct pernet_operations pedit_net_ops = {
509 	.init = pedit_init_net,
510 	.exit_batch = pedit_exit_net,
511 	.id   = &pedit_net_id,
512 	.size = sizeof(struct tc_action_net),
513 };
514 
515 MODULE_AUTHOR("Jamal Hadi Salim(2002-4)");
516 MODULE_DESCRIPTION("Generic Packet Editor actions");
517 MODULE_LICENSE("GPL");
518 
519 static int __init pedit_init_module(void)
520 {
521 	return tcf_register_action(&act_pedit_ops, &pedit_net_ops);
522 }
523 
524 static void __exit pedit_cleanup_module(void)
525 {
526 	tcf_unregister_action(&act_pedit_ops, &pedit_net_ops);
527 }
528 
529 module_init(pedit_init_module);
530 module_exit(pedit_cleanup_module);
531