xref: /linux/net/sched/act_pedit.c (revision 0889d07f3e4b171c453b2aaf2b257f9074cdf624) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * net/sched/act_pedit.c	Generic packet editor
4  *
5  * Authors:	Jamal Hadi Salim (2002-4)
6  */
7 
8 #include <linux/types.h>
9 #include <linux/kernel.h>
10 #include <linux/string.h>
11 #include <linux/errno.h>
12 #include <linux/skbuff.h>
13 #include <linux/rtnetlink.h>
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/slab.h>
17 #include <net/netlink.h>
18 #include <net/pkt_sched.h>
19 #include <linux/tc_act/tc_pedit.h>
20 #include <net/tc_act/tc_pedit.h>
21 #include <uapi/linux/tc_act/tc_pedit.h>
22 #include <net/pkt_cls.h>
23 
24 static unsigned int pedit_net_id;
25 static struct tc_action_ops act_pedit_ops;
26 
27 static const struct nla_policy pedit_policy[TCA_PEDIT_MAX + 1] = {
28 	[TCA_PEDIT_PARMS]	= { .len = sizeof(struct tc_pedit) },
29 	[TCA_PEDIT_KEYS_EX]   = { .type = NLA_NESTED },
30 };
31 
32 static const struct nla_policy pedit_key_ex_policy[TCA_PEDIT_KEY_EX_MAX + 1] = {
33 	[TCA_PEDIT_KEY_EX_HTYPE]  = { .type = NLA_U16 },
34 	[TCA_PEDIT_KEY_EX_CMD]	  = { .type = NLA_U16 },
35 };
36 
37 static struct tcf_pedit_key_ex *tcf_pedit_keys_ex_parse(struct nlattr *nla,
38 							u8 n)
39 {
40 	struct tcf_pedit_key_ex *keys_ex;
41 	struct tcf_pedit_key_ex *k;
42 	const struct nlattr *ka;
43 	int err = -EINVAL;
44 	int rem;
45 
46 	if (!nla || !n)
47 		return NULL;
48 
49 	keys_ex = kcalloc(n, sizeof(*k), GFP_KERNEL);
50 	if (!keys_ex)
51 		return ERR_PTR(-ENOMEM);
52 
53 	k = keys_ex;
54 
55 	nla_for_each_nested(ka, nla, rem) {
56 		struct nlattr *tb[TCA_PEDIT_KEY_EX_MAX + 1];
57 
58 		if (!n) {
59 			err = -EINVAL;
60 			goto err_out;
61 		}
62 		n--;
63 
64 		if (nla_type(ka) != TCA_PEDIT_KEY_EX) {
65 			err = -EINVAL;
66 			goto err_out;
67 		}
68 
69 		err = nla_parse_nested_deprecated(tb, TCA_PEDIT_KEY_EX_MAX,
70 						  ka, pedit_key_ex_policy,
71 						  NULL);
72 		if (err)
73 			goto err_out;
74 
75 		if (!tb[TCA_PEDIT_KEY_EX_HTYPE] ||
76 		    !tb[TCA_PEDIT_KEY_EX_CMD]) {
77 			err = -EINVAL;
78 			goto err_out;
79 		}
80 
81 		k->htype = nla_get_u16(tb[TCA_PEDIT_KEY_EX_HTYPE]);
82 		k->cmd = nla_get_u16(tb[TCA_PEDIT_KEY_EX_CMD]);
83 
84 		if (k->htype > TCA_PEDIT_HDR_TYPE_MAX ||
85 		    k->cmd > TCA_PEDIT_CMD_MAX) {
86 			err = -EINVAL;
87 			goto err_out;
88 		}
89 
90 		k++;
91 	}
92 
93 	if (n) {
94 		err = -EINVAL;
95 		goto err_out;
96 	}
97 
98 	return keys_ex;
99 
100 err_out:
101 	kfree(keys_ex);
102 	return ERR_PTR(err);
103 }
104 
105 static int tcf_pedit_key_ex_dump(struct sk_buff *skb,
106 				 struct tcf_pedit_key_ex *keys_ex, int n)
107 {
108 	struct nlattr *keys_start = nla_nest_start_noflag(skb,
109 							  TCA_PEDIT_KEYS_EX);
110 
111 	if (!keys_start)
112 		goto nla_failure;
113 	for (; n > 0; n--) {
114 		struct nlattr *key_start;
115 
116 		key_start = nla_nest_start_noflag(skb, TCA_PEDIT_KEY_EX);
117 		if (!key_start)
118 			goto nla_failure;
119 
120 		if (nla_put_u16(skb, TCA_PEDIT_KEY_EX_HTYPE, keys_ex->htype) ||
121 		    nla_put_u16(skb, TCA_PEDIT_KEY_EX_CMD, keys_ex->cmd))
122 			goto nla_failure;
123 
124 		nla_nest_end(skb, key_start);
125 
126 		keys_ex++;
127 	}
128 
129 	nla_nest_end(skb, keys_start);
130 
131 	return 0;
132 nla_failure:
133 	nla_nest_cancel(skb, keys_start);
134 	return -EINVAL;
135 }
136 
137 static int tcf_pedit_init(struct net *net, struct nlattr *nla,
138 			  struct nlattr *est, struct tc_action **a,
139 			  int ovr, int bind, bool rtnl_held,
140 			  struct tcf_proto *tp, struct netlink_ext_ack *extack)
141 {
142 	struct tc_action_net *tn = net_generic(net, pedit_net_id);
143 	struct nlattr *tb[TCA_PEDIT_MAX + 1];
144 	struct tcf_chain *goto_ch = NULL;
145 	struct tc_pedit_key *keys = NULL;
146 	struct tcf_pedit_key_ex *keys_ex;
147 	struct tc_pedit *parm;
148 	struct nlattr *pattr;
149 	struct tcf_pedit *p;
150 	int ret = 0, err;
151 	int ksize;
152 	u32 index;
153 
154 	if (!nla) {
155 		NL_SET_ERR_MSG_MOD(extack, "Pedit requires attributes to be passed");
156 		return -EINVAL;
157 	}
158 
159 	err = nla_parse_nested_deprecated(tb, TCA_PEDIT_MAX, nla,
160 					  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 	index = parm->index;
184 	err = tcf_idr_check_alloc(tn, &index, a, bind);
185 	if (!err) {
186 		if (!parm->nkeys) {
187 			tcf_idr_cleanup(tn, index);
188 			NL_SET_ERR_MSG_MOD(extack, "Pedit requires keys to be passed");
189 			ret = -EINVAL;
190 			goto out_free;
191 		}
192 		ret = tcf_idr_create(tn, index, est, a,
193 				     &act_pedit_ops, bind, false);
194 		if (ret) {
195 			tcf_idr_cleanup(tn, index);
196 			goto out_free;
197 		}
198 		ret = ACT_P_CREATED;
199 	} else if (err > 0) {
200 		if (bind)
201 			goto out_free;
202 		if (!ovr) {
203 			ret = -EEXIST;
204 			goto out_release;
205 		}
206 	} else {
207 		ret = err;
208 		goto out_free;
209 	}
210 
211 	err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
212 	if (err < 0) {
213 		ret = err;
214 		goto out_release;
215 	}
216 	p = to_pedit(*a);
217 	spin_lock_bh(&p->tcf_lock);
218 
219 	if (ret == ACT_P_CREATED ||
220 	    (p->tcfp_nkeys && p->tcfp_nkeys != parm->nkeys)) {
221 		keys = kmalloc(ksize, GFP_ATOMIC);
222 		if (!keys) {
223 			spin_unlock_bh(&p->tcf_lock);
224 			ret = -ENOMEM;
225 			goto put_chain;
226 		}
227 		kfree(p->tcfp_keys);
228 		p->tcfp_keys = keys;
229 		p->tcfp_nkeys = parm->nkeys;
230 	}
231 	memcpy(p->tcfp_keys, parm->keys, ksize);
232 
233 	p->tcfp_flags = parm->flags;
234 	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
235 
236 	kfree(p->tcfp_keys_ex);
237 	p->tcfp_keys_ex = keys_ex;
238 
239 	spin_unlock_bh(&p->tcf_lock);
240 	if (goto_ch)
241 		tcf_chain_put_by_act(goto_ch);
242 	if (ret == ACT_P_CREATED)
243 		tcf_idr_insert(tn, *a);
244 	return ret;
245 
246 put_chain:
247 	if (goto_ch)
248 		tcf_chain_put_by_act(goto_ch);
249 out_release:
250 	tcf_idr_release(*a, bind);
251 out_free:
252 	kfree(keys_ex);
253 	return ret;
254 
255 }
256 
257 static void tcf_pedit_cleanup(struct tc_action *a)
258 {
259 	struct tcf_pedit *p = to_pedit(a);
260 	struct tc_pedit_key *keys = p->tcfp_keys;
261 
262 	kfree(keys);
263 	kfree(p->tcfp_keys_ex);
264 }
265 
266 static bool offset_valid(struct sk_buff *skb, int offset)
267 {
268 	if (offset > 0 && offset > skb->len)
269 		return false;
270 
271 	if  (offset < 0 && -offset > skb_headroom(skb))
272 		return false;
273 
274 	return true;
275 }
276 
277 static int pedit_skb_hdr_offset(struct sk_buff *skb,
278 				enum pedit_header_type htype, int *hoffset)
279 {
280 	int ret = -EINVAL;
281 
282 	switch (htype) {
283 	case TCA_PEDIT_KEY_EX_HDR_TYPE_ETH:
284 		if (skb_mac_header_was_set(skb)) {
285 			*hoffset = skb_mac_offset(skb);
286 			ret = 0;
287 		}
288 		break;
289 	case TCA_PEDIT_KEY_EX_HDR_TYPE_NETWORK:
290 	case TCA_PEDIT_KEY_EX_HDR_TYPE_IP4:
291 	case TCA_PEDIT_KEY_EX_HDR_TYPE_IP6:
292 		*hoffset = skb_network_offset(skb);
293 		ret = 0;
294 		break;
295 	case TCA_PEDIT_KEY_EX_HDR_TYPE_TCP:
296 	case TCA_PEDIT_KEY_EX_HDR_TYPE_UDP:
297 		if (skb_transport_header_was_set(skb)) {
298 			*hoffset = skb_transport_offset(skb);
299 			ret = 0;
300 		}
301 		break;
302 	default:
303 		ret = -EINVAL;
304 		break;
305 	}
306 
307 	return ret;
308 }
309 
310 static int tcf_pedit_act(struct sk_buff *skb, const struct tc_action *a,
311 			 struct tcf_result *res)
312 {
313 	struct tcf_pedit *p = to_pedit(a);
314 	int i;
315 
316 	if (skb_unclone(skb, GFP_ATOMIC))
317 		return p->tcf_action;
318 
319 	spin_lock(&p->tcf_lock);
320 
321 	tcf_lastuse_update(&p->tcf_tm);
322 
323 	if (p->tcfp_nkeys > 0) {
324 		struct tc_pedit_key *tkey = p->tcfp_keys;
325 		struct tcf_pedit_key_ex *tkey_ex = p->tcfp_keys_ex;
326 		enum pedit_header_type htype =
327 			TCA_PEDIT_KEY_EX_HDR_TYPE_NETWORK;
328 		enum pedit_cmd cmd = TCA_PEDIT_KEY_EX_CMD_SET;
329 
330 		for (i = p->tcfp_nkeys; i > 0; i--, tkey++) {
331 			u32 *ptr, hdata;
332 			int offset = tkey->off;
333 			int hoffset;
334 			u32 val;
335 			int rc;
336 
337 			if (tkey_ex) {
338 				htype = tkey_ex->htype;
339 				cmd = tkey_ex->cmd;
340 
341 				tkey_ex++;
342 			}
343 
344 			rc = pedit_skb_hdr_offset(skb, htype, &hoffset);
345 			if (rc) {
346 				pr_info("tc action pedit bad header type specified (0x%x)\n",
347 					htype);
348 				goto bad;
349 			}
350 
351 			if (tkey->offmask) {
352 				u8 *d, _d;
353 
354 				if (!offset_valid(skb, hoffset + tkey->at)) {
355 					pr_info("tc action pedit 'at' offset %d out of bounds\n",
356 						hoffset + tkey->at);
357 					goto bad;
358 				}
359 				d = skb_header_pointer(skb, hoffset + tkey->at,
360 						       sizeof(_d), &_d);
361 				if (!d)
362 					goto bad;
363 				offset += (*d & tkey->offmask) >> tkey->shift;
364 			}
365 
366 			if (offset % 4) {
367 				pr_info("tc action pedit offset must be on 32 bit boundaries\n");
368 				goto bad;
369 			}
370 
371 			if (!offset_valid(skb, hoffset + offset)) {
372 				pr_info("tc action pedit offset %d out of bounds\n",
373 					hoffset + offset);
374 				goto bad;
375 			}
376 
377 			ptr = skb_header_pointer(skb, hoffset + offset,
378 						 sizeof(hdata), &hdata);
379 			if (!ptr)
380 				goto bad;
381 			/* just do it, baby */
382 			switch (cmd) {
383 			case TCA_PEDIT_KEY_EX_CMD_SET:
384 				val = tkey->val;
385 				break;
386 			case TCA_PEDIT_KEY_EX_CMD_ADD:
387 				val = (*ptr + tkey->val) & ~tkey->mask;
388 				break;
389 			default:
390 				pr_info("tc action pedit bad command (%d)\n",
391 					cmd);
392 				goto bad;
393 			}
394 
395 			*ptr = ((*ptr & tkey->mask) ^ val);
396 			if (ptr == &hdata)
397 				skb_store_bits(skb, hoffset + offset, ptr, 4);
398 		}
399 
400 		goto done;
401 	} else {
402 		WARN(1, "pedit BUG: index %d\n", p->tcf_index);
403 	}
404 
405 bad:
406 	p->tcf_qstats.overlimits++;
407 done:
408 	bstats_update(&p->tcf_bstats, skb);
409 	spin_unlock(&p->tcf_lock);
410 	return p->tcf_action;
411 }
412 
413 static int tcf_pedit_dump(struct sk_buff *skb, struct tc_action *a,
414 			  int bind, int ref)
415 {
416 	unsigned char *b = skb_tail_pointer(skb);
417 	struct tcf_pedit *p = to_pedit(a);
418 	struct tc_pedit *opt;
419 	struct tcf_t t;
420 	int s;
421 
422 	s = struct_size(opt, keys, p->tcfp_nkeys);
423 
424 	/* netlink spinlocks held above us - must use ATOMIC */
425 	opt = kzalloc(s, GFP_ATOMIC);
426 	if (unlikely(!opt))
427 		return -ENOBUFS;
428 
429 	spin_lock_bh(&p->tcf_lock);
430 	memcpy(opt->keys, p->tcfp_keys,
431 	       p->tcfp_nkeys * sizeof(struct tc_pedit_key));
432 	opt->index = p->tcf_index;
433 	opt->nkeys = p->tcfp_nkeys;
434 	opt->flags = p->tcfp_flags;
435 	opt->action = p->tcf_action;
436 	opt->refcnt = refcount_read(&p->tcf_refcnt) - ref;
437 	opt->bindcnt = atomic_read(&p->tcf_bindcnt) - bind;
438 
439 	if (p->tcfp_keys_ex) {
440 		if (tcf_pedit_key_ex_dump(skb,
441 					  p->tcfp_keys_ex,
442 					  p->tcfp_nkeys))
443 			goto nla_put_failure;
444 
445 		if (nla_put(skb, TCA_PEDIT_PARMS_EX, s, opt))
446 			goto nla_put_failure;
447 	} else {
448 		if (nla_put(skb, TCA_PEDIT_PARMS, s, opt))
449 			goto nla_put_failure;
450 	}
451 
452 	tcf_tm_dump(&t, &p->tcf_tm);
453 	if (nla_put_64bit(skb, TCA_PEDIT_TM, sizeof(t), &t, TCA_PEDIT_PAD))
454 		goto nla_put_failure;
455 	spin_unlock_bh(&p->tcf_lock);
456 
457 	kfree(opt);
458 	return skb->len;
459 
460 nla_put_failure:
461 	spin_unlock_bh(&p->tcf_lock);
462 	nlmsg_trim(skb, b);
463 	kfree(opt);
464 	return -1;
465 }
466 
467 static int tcf_pedit_walker(struct net *net, struct sk_buff *skb,
468 			    struct netlink_callback *cb, int type,
469 			    const struct tc_action_ops *ops,
470 			    struct netlink_ext_ack *extack)
471 {
472 	struct tc_action_net *tn = net_generic(net, pedit_net_id);
473 
474 	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
475 }
476 
477 static int tcf_pedit_search(struct net *net, struct tc_action **a, u32 index)
478 {
479 	struct tc_action_net *tn = net_generic(net, pedit_net_id);
480 
481 	return tcf_idr_search(tn, a, index);
482 }
483 
484 static struct tc_action_ops act_pedit_ops = {
485 	.kind		=	"pedit",
486 	.id		=	TCA_ID_PEDIT,
487 	.owner		=	THIS_MODULE,
488 	.act		=	tcf_pedit_act,
489 	.dump		=	tcf_pedit_dump,
490 	.cleanup	=	tcf_pedit_cleanup,
491 	.init		=	tcf_pedit_init,
492 	.walk		=	tcf_pedit_walker,
493 	.lookup		=	tcf_pedit_search,
494 	.size		=	sizeof(struct tcf_pedit),
495 };
496 
497 static __net_init int pedit_init_net(struct net *net)
498 {
499 	struct tc_action_net *tn = net_generic(net, pedit_net_id);
500 
501 	return tc_action_net_init(net, tn, &act_pedit_ops);
502 }
503 
504 static void __net_exit pedit_exit_net(struct list_head *net_list)
505 {
506 	tc_action_net_exit(net_list, pedit_net_id);
507 }
508 
509 static struct pernet_operations pedit_net_ops = {
510 	.init = pedit_init_net,
511 	.exit_batch = pedit_exit_net,
512 	.id   = &pedit_net_id,
513 	.size = sizeof(struct tc_action_net),
514 };
515 
516 MODULE_AUTHOR("Jamal Hadi Salim(2002-4)");
517 MODULE_DESCRIPTION("Generic Packet Editor actions");
518 MODULE_LICENSE("GPL");
519 
520 static int __init pedit_init_module(void)
521 {
522 	return tcf_register_action(&act_pedit_ops, &pedit_net_ops);
523 }
524 
525 static void __exit pedit_cleanup_module(void)
526 {
527 	tcf_unregister_action(&act_pedit_ops, &pedit_net_ops);
528 }
529 
530 module_init(pedit_init_module);
531 module_exit(pedit_cleanup_module);
532