Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * net/sched/ematch.c Extended Match API | |
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: Thomas Graf <tgraf@suug.ch> | |
10 | * | |
11 | * ========================================================================== | |
12 | * | |
13 | * An extended match (ematch) is a small classification tool not worth | |
14 | * writing a full classifier for. Ematches can be interconnected to form | |
15 | * a logic expression and get attached to classifiers to extend their | |
16 | * functionatlity. | |
17 | * | |
18 | * The userspace part transforms the logic expressions into an array | |
19 | * consisting of multiple sequences of interconnected ematches separated | |
20 | * by markers. Precedence is implemented by a special ematch kind | |
21 | * referencing a sequence beyond the marker of the current sequence | |
22 | * causing the current position in the sequence to be pushed onto a stack | |
23 | * to allow the current position to be overwritten by the position referenced | |
24 | * in the special ematch. Matching continues in the new sequence until a | |
25 | * marker is reached causing the position to be restored from the stack. | |
26 | * | |
27 | * Example: | |
28 | * A AND (B1 OR B2) AND C AND D | |
29 | * | |
30 | * ------->-PUSH------- | |
31 | * -->-- / -->-- \ -->-- | |
32 | * / \ / / \ \ / \ | |
33 | * +-------+-------+-------+-------+-------+--------+ | |
34 | * | A AND | B AND | C AND | D END | B1 OR | B2 END | | |
35 | * +-------+-------+-------+-------+-------+--------+ | |
36 | * \ / | |
37 | * --------<-POP--------- | |
38 | * | |
39 | * where B is a virtual ematch referencing to sequence starting with B1. | |
10297b99 | 40 | * |
1da177e4 LT |
41 | * ========================================================================== |
42 | * | |
43 | * How to write an ematch in 60 seconds | |
44 | * ------------------------------------ | |
10297b99 | 45 | * |
1da177e4 LT |
46 | * 1) Provide a matcher function: |
47 | * static int my_match(struct sk_buff *skb, struct tcf_ematch *m, | |
48 | * struct tcf_pkt_info *info) | |
49 | * { | |
50 | * struct mydata *d = (struct mydata *) m->data; | |
51 | * | |
52 | * if (...matching goes here...) | |
53 | * return 1; | |
54 | * else | |
55 | * return 0; | |
56 | * } | |
57 | * | |
58 | * 2) Fill out a struct tcf_ematch_ops: | |
59 | * static struct tcf_ematch_ops my_ops = { | |
60 | * .kind = unique id, | |
61 | * .datalen = sizeof(struct mydata), | |
62 | * .match = my_match, | |
63 | * .owner = THIS_MODULE, | |
64 | * }; | |
65 | * | |
66 | * 3) Register/Unregister your ematch: | |
67 | * static int __init init_my_ematch(void) | |
68 | * { | |
69 | * return tcf_em_register(&my_ops); | |
70 | * } | |
71 | * | |
72 | * static void __exit exit_my_ematch(void) | |
73 | * { | |
4d24b52a | 74 | * tcf_em_unregister(&my_ops); |
1da177e4 LT |
75 | * } |
76 | * | |
77 | * module_init(init_my_ematch); | |
78 | * module_exit(exit_my_ematch); | |
79 | * | |
80 | * 4) By now you should have two more seconds left, barely enough to | |
81 | * open up a beer to watch the compilation going. | |
82 | */ | |
83 | ||
1da177e4 LT |
84 | #include <linux/module.h> |
85 | #include <linux/types.h> | |
86 | #include <linux/kernel.h> | |
1da177e4 | 87 | #include <linux/errno.h> |
1da177e4 LT |
88 | #include <linux/rtnetlink.h> |
89 | #include <linux/skbuff.h> | |
90 | #include <net/pkt_cls.h> | |
1da177e4 LT |
91 | |
92 | static LIST_HEAD(ematch_ops); | |
93 | static DEFINE_RWLOCK(ematch_mod_lock); | |
94 | ||
95 | static inline struct tcf_ematch_ops * tcf_em_lookup(u16 kind) | |
96 | { | |
97 | struct tcf_ematch_ops *e = NULL; | |
98 | ||
99 | read_lock(&ematch_mod_lock); | |
100 | list_for_each_entry(e, &ematch_ops, link) { | |
101 | if (kind == e->kind) { | |
102 | if (!try_module_get(e->owner)) | |
103 | e = NULL; | |
104 | read_unlock(&ematch_mod_lock); | |
105 | return e; | |
106 | } | |
107 | } | |
108 | read_unlock(&ematch_mod_lock); | |
109 | ||
110 | return NULL; | |
111 | } | |
112 | ||
113 | /** | |
114 | * tcf_em_register - register an extended match | |
10297b99 | 115 | * |
1da177e4 LT |
116 | * @ops: ematch operations lookup table |
117 | * | |
118 | * This function must be called by ematches to announce their presence. | |
119 | * The given @ops must have kind set to a unique identifier and the | |
120 | * callback match() must be implemented. All other callbacks are optional | |
121 | * and a fallback implementation is used instead. | |
122 | * | |
123 | * Returns -EEXISTS if an ematch of the same kind has already registered. | |
124 | */ | |
125 | int tcf_em_register(struct tcf_ematch_ops *ops) | |
126 | { | |
127 | int err = -EEXIST; | |
128 | struct tcf_ematch_ops *e; | |
129 | ||
130 | if (ops->match == NULL) | |
131 | return -EINVAL; | |
132 | ||
133 | write_lock(&ematch_mod_lock); | |
134 | list_for_each_entry(e, &ematch_ops, link) | |
135 | if (ops->kind == e->kind) | |
136 | goto errout; | |
137 | ||
138 | list_add_tail(&ops->link, &ematch_ops); | |
139 | err = 0; | |
140 | errout: | |
141 | write_unlock(&ematch_mod_lock); | |
142 | return err; | |
143 | } | |
62e3ba1b | 144 | EXPORT_SYMBOL(tcf_em_register); |
1da177e4 LT |
145 | |
146 | /** | |
147 | * tcf_em_unregister - unregster and extended match | |
148 | * | |
149 | * @ops: ematch operations lookup table | |
150 | * | |
151 | * This function must be called by ematches to announce their disappearance | |
152 | * for examples when the module gets unloaded. The @ops parameter must be | |
153 | * the same as the one used for registration. | |
154 | * | |
155 | * Returns -ENOENT if no matching ematch was found. | |
156 | */ | |
4d24b52a | 157 | void tcf_em_unregister(struct tcf_ematch_ops *ops) |
1da177e4 | 158 | { |
1da177e4 | 159 | write_lock(&ematch_mod_lock); |
4d24b52a | 160 | list_del(&ops->link); |
1da177e4 | 161 | write_unlock(&ematch_mod_lock); |
1da177e4 | 162 | } |
62e3ba1b | 163 | EXPORT_SYMBOL(tcf_em_unregister); |
1da177e4 LT |
164 | |
165 | static inline struct tcf_ematch * tcf_em_get_match(struct tcf_ematch_tree *tree, | |
166 | int index) | |
167 | { | |
168 | return &tree->matches[index]; | |
169 | } | |
170 | ||
171 | ||
172 | static int tcf_em_validate(struct tcf_proto *tp, | |
173 | struct tcf_ematch_tree_hdr *tree_hdr, | |
add93b61 | 174 | struct tcf_ematch *em, struct nlattr *nla, int idx) |
1da177e4 LT |
175 | { |
176 | int err = -EINVAL; | |
add93b61 PM |
177 | struct tcf_ematch_hdr *em_hdr = nla_data(nla); |
178 | int data_len = nla_len(nla) - sizeof(*em_hdr); | |
1da177e4 LT |
179 | void *data = (void *) em_hdr + sizeof(*em_hdr); |
180 | ||
181 | if (!TCF_EM_REL_VALID(em_hdr->flags)) | |
182 | goto errout; | |
183 | ||
184 | if (em_hdr->kind == TCF_EM_CONTAINER) { | |
185 | /* Special ematch called "container", carries an index | |
186 | * referencing an external ematch sequence. */ | |
187 | u32 ref; | |
188 | ||
189 | if (data_len < sizeof(ref)) | |
190 | goto errout; | |
191 | ref = *(u32 *) data; | |
192 | ||
193 | if (ref >= tree_hdr->nmatches) | |
194 | goto errout; | |
195 | ||
196 | /* We do not allow backward jumps to avoid loops and jumps | |
197 | * to our own position are of course illegal. */ | |
198 | if (ref <= idx) | |
199 | goto errout; | |
200 | ||
10297b99 | 201 | |
1da177e4 LT |
202 | em->data = ref; |
203 | } else { | |
204 | /* Note: This lookup will increase the module refcnt | |
205 | * of the ematch module referenced. In case of a failure, | |
206 | * a destroy function is called by the underlying layer | |
207 | * which automatically releases the reference again, therefore | |
208 | * the module MUST not be given back under any circumstances | |
209 | * here. Be aware, the destroy function assumes that the | |
210 | * module is held if the ops field is non zero. */ | |
211 | em->ops = tcf_em_lookup(em_hdr->kind); | |
212 | ||
213 | if (em->ops == NULL) { | |
214 | err = -ENOENT; | |
95a5afca | 215 | #ifdef CONFIG_MODULES |
db3d99c0 PM |
216 | __rtnl_unlock(); |
217 | request_module("ematch-kind-%u", em_hdr->kind); | |
218 | rtnl_lock(); | |
219 | em->ops = tcf_em_lookup(em_hdr->kind); | |
220 | if (em->ops) { | |
221 | /* We dropped the RTNL mutex in order to | |
222 | * perform the module load. Tell the caller | |
223 | * to replay the request. */ | |
224 | module_put(em->ops->owner); | |
225 | err = -EAGAIN; | |
226 | } | |
227 | #endif | |
1da177e4 LT |
228 | goto errout; |
229 | } | |
230 | ||
231 | /* ematch module provides expected length of data, so we | |
232 | * can do a basic sanity check. */ | |
233 | if (em->ops->datalen && data_len < em->ops->datalen) | |
234 | goto errout; | |
235 | ||
236 | if (em->ops->change) { | |
237 | err = em->ops->change(tp, data, data_len, em); | |
238 | if (err < 0) | |
239 | goto errout; | |
240 | } else if (data_len > 0) { | |
241 | /* ematch module doesn't provide an own change | |
242 | * procedure and expects us to allocate and copy | |
243 | * the ematch data. | |
244 | * | |
245 | * TCF_EM_SIMPLE may be specified stating that the | |
246 | * data only consists of a u32 integer and the module | |
247 | * does not expected a memory reference but rather | |
248 | * the value carried. */ | |
249 | if (em_hdr->flags & TCF_EM_SIMPLE) { | |
250 | if (data_len < sizeof(u32)) | |
251 | goto errout; | |
252 | em->data = *(u32 *) data; | |
253 | } else { | |
c7b1b249 | 254 | void *v = kmemdup(data, data_len, GFP_KERNEL); |
1da177e4 LT |
255 | if (v == NULL) { |
256 | err = -ENOBUFS; | |
257 | goto errout; | |
258 | } | |
1da177e4 LT |
259 | em->data = (unsigned long) v; |
260 | } | |
261 | } | |
262 | } | |
263 | ||
264 | em->matchid = em_hdr->matchid; | |
265 | em->flags = em_hdr->flags; | |
266 | em->datalen = data_len; | |
267 | ||
268 | err = 0; | |
269 | errout: | |
270 | return err; | |
271 | } | |
272 | ||
7a9c1bd4 PM |
273 | static const struct nla_policy em_policy[TCA_EMATCH_TREE_MAX + 1] = { |
274 | [TCA_EMATCH_TREE_HDR] = { .len = sizeof(struct tcf_ematch_tree_hdr) }, | |
275 | [TCA_EMATCH_TREE_LIST] = { .type = NLA_NESTED }, | |
276 | }; | |
277 | ||
1da177e4 LT |
278 | /** |
279 | * tcf_em_tree_validate - validate ematch config TLV and build ematch tree | |
280 | * | |
281 | * @tp: classifier kind handle | |
add93b61 | 282 | * @nla: ematch tree configuration TLV |
1da177e4 LT |
283 | * @tree: destination ematch tree variable to store the resulting |
284 | * ematch tree. | |
285 | * | |
add93b61 | 286 | * This function validates the given configuration TLV @nla and builds an |
1da177e4 LT |
287 | * ematch tree in @tree. The resulting tree must later be copied into |
288 | * the private classifier data using tcf_em_tree_change(). You MUST NOT | |
289 | * provide the ematch tree variable of the private classifier data directly, | |
290 | * the changes would not be locked properly. | |
291 | * | |
292 | * Returns a negative error code if the configuration TLV contains errors. | |
293 | */ | |
add93b61 | 294 | int tcf_em_tree_validate(struct tcf_proto *tp, struct nlattr *nla, |
1da177e4 LT |
295 | struct tcf_ematch_tree *tree) |
296 | { | |
cee63723 | 297 | int idx, list_len, matches_len, err; |
add93b61 PM |
298 | struct nlattr *tb[TCA_EMATCH_TREE_MAX + 1]; |
299 | struct nlattr *rt_match, *rt_hdr, *rt_list; | |
1da177e4 LT |
300 | struct tcf_ematch_tree_hdr *tree_hdr; |
301 | struct tcf_ematch *em; | |
302 | ||
268bcca1 SH |
303 | memset(tree, 0, sizeof(*tree)); |
304 | if (!nla) | |
b541ca2c | 305 | return 0; |
b541ca2c | 306 | |
7a9c1bd4 | 307 | err = nla_parse_nested(tb, TCA_EMATCH_TREE_MAX, nla, em_policy); |
cee63723 | 308 | if (err < 0) |
1da177e4 LT |
309 | goto errout; |
310 | ||
cee63723 | 311 | err = -EINVAL; |
add93b61 PM |
312 | rt_hdr = tb[TCA_EMATCH_TREE_HDR]; |
313 | rt_list = tb[TCA_EMATCH_TREE_LIST]; | |
1da177e4 LT |
314 | |
315 | if (rt_hdr == NULL || rt_list == NULL) | |
316 | goto errout; | |
317 | ||
add93b61 | 318 | tree_hdr = nla_data(rt_hdr); |
1da177e4 LT |
319 | memcpy(&tree->hdr, tree_hdr, sizeof(*tree_hdr)); |
320 | ||
add93b61 PM |
321 | rt_match = nla_data(rt_list); |
322 | list_len = nla_len(rt_list); | |
1da177e4 LT |
323 | matches_len = tree_hdr->nmatches * sizeof(*em); |
324 | ||
0da974f4 | 325 | tree->matches = kzalloc(matches_len, GFP_KERNEL); |
1da177e4 LT |
326 | if (tree->matches == NULL) |
327 | goto errout; | |
1da177e4 | 328 | |
add93b61 | 329 | /* We do not use nla_parse_nested here because the maximum |
1da177e4 LT |
330 | * number of attributes is unknown. This saves us the allocation |
331 | * for a tb buffer which would serve no purpose at all. | |
10297b99 | 332 | * |
1da177e4 LT |
333 | * The array of rt attributes is parsed in the order as they are |
334 | * provided, their type must be incremental from 1 to n. Even | |
335 | * if it does not serve any real purpose, a failure of sticking | |
336 | * to this policy will result in parsing failure. */ | |
add93b61 | 337 | for (idx = 0; nla_ok(rt_match, list_len); idx++) { |
1da177e4 LT |
338 | err = -EINVAL; |
339 | ||
add93b61 | 340 | if (rt_match->nla_type != (idx + 1)) |
1da177e4 LT |
341 | goto errout_abort; |
342 | ||
343 | if (idx >= tree_hdr->nmatches) | |
344 | goto errout_abort; | |
345 | ||
add93b61 | 346 | if (nla_len(rt_match) < sizeof(struct tcf_ematch_hdr)) |
1da177e4 LT |
347 | goto errout_abort; |
348 | ||
349 | em = tcf_em_get_match(tree, idx); | |
350 | ||
351 | err = tcf_em_validate(tp, tree_hdr, em, rt_match, idx); | |
352 | if (err < 0) | |
353 | goto errout_abort; | |
354 | ||
add93b61 | 355 | rt_match = nla_next(rt_match, &list_len); |
1da177e4 LT |
356 | } |
357 | ||
358 | /* Check if the number of matches provided by userspace actually | |
359 | * complies with the array of matches. The number was used for | |
360 | * the validation of references and a mismatch could lead to | |
361 | * undefined references during the matching process. */ | |
362 | if (idx != tree_hdr->nmatches) { | |
363 | err = -EINVAL; | |
364 | goto errout_abort; | |
365 | } | |
366 | ||
367 | err = 0; | |
368 | errout: | |
369 | return err; | |
370 | ||
371 | errout_abort: | |
372 | tcf_em_tree_destroy(tp, tree); | |
373 | return err; | |
374 | } | |
62e3ba1b | 375 | EXPORT_SYMBOL(tcf_em_tree_validate); |
1da177e4 LT |
376 | |
377 | /** | |
378 | * tcf_em_tree_destroy - destroy an ematch tree | |
379 | * | |
380 | * @tp: classifier kind handle | |
381 | * @tree: ematch tree to be deleted | |
382 | * | |
383 | * This functions destroys an ematch tree previously created by | |
384 | * tcf_em_tree_validate()/tcf_em_tree_change(). You must ensure that | |
385 | * the ematch tree is not in use before calling this function. | |
386 | */ | |
387 | void tcf_em_tree_destroy(struct tcf_proto *tp, struct tcf_ematch_tree *tree) | |
388 | { | |
389 | int i; | |
390 | ||
391 | if (tree->matches == NULL) | |
392 | return; | |
393 | ||
394 | for (i = 0; i < tree->hdr.nmatches; i++) { | |
395 | struct tcf_ematch *em = tcf_em_get_match(tree, i); | |
396 | ||
397 | if (em->ops) { | |
398 | if (em->ops->destroy) | |
399 | em->ops->destroy(tp, em); | |
954415e3 | 400 | else if (!tcf_em_is_simple(em)) |
30ddb159 | 401 | kfree((void *) em->data); |
1da177e4 LT |
402 | module_put(em->ops->owner); |
403 | } | |
404 | } | |
10297b99 | 405 | |
1da177e4 LT |
406 | tree->hdr.nmatches = 0; |
407 | kfree(tree->matches); | |
954415e3 | 408 | tree->matches = NULL; |
1da177e4 | 409 | } |
62e3ba1b | 410 | EXPORT_SYMBOL(tcf_em_tree_destroy); |
1da177e4 LT |
411 | |
412 | /** | |
413 | * tcf_em_tree_dump - dump ematch tree into a rtnl message | |
414 | * | |
415 | * @skb: skb holding the rtnl message | |
416 | * @t: ematch tree to be dumped | |
417 | * @tlv: TLV type to be used to encapsulate the tree | |
418 | * | |
419 | * This function dumps a ematch tree into a rtnl message. It is valid to | |
420 | * call this function while the ematch tree is in use. | |
421 | * | |
422 | * Returns -1 if the skb tailroom is insufficient. | |
423 | */ | |
424 | int tcf_em_tree_dump(struct sk_buff *skb, struct tcf_ematch_tree *tree, int tlv) | |
425 | { | |
426 | int i; | |
27a884dc | 427 | u8 *tail; |
4b3550ef | 428 | struct nlattr *top_start; |
add93b61 | 429 | struct nlattr *list_start; |
1da177e4 | 430 | |
4b3550ef PM |
431 | top_start = nla_nest_start(skb, tlv); |
432 | if (top_start == NULL) | |
433 | goto nla_put_failure; | |
434 | ||
add93b61 | 435 | NLA_PUT(skb, TCA_EMATCH_TREE_HDR, sizeof(tree->hdr), &tree->hdr); |
1da177e4 | 436 | |
4b3550ef PM |
437 | list_start = nla_nest_start(skb, TCA_EMATCH_TREE_LIST); |
438 | if (list_start == NULL) | |
439 | goto nla_put_failure; | |
1da177e4 | 440 | |
27a884dc | 441 | tail = skb_tail_pointer(skb); |
1da177e4 | 442 | for (i = 0; i < tree->hdr.nmatches; i++) { |
add93b61 | 443 | struct nlattr *match_start = (struct nlattr *)tail; |
1da177e4 LT |
444 | struct tcf_ematch *em = tcf_em_get_match(tree, i); |
445 | struct tcf_ematch_hdr em_hdr = { | |
446 | .kind = em->ops ? em->ops->kind : TCF_EM_CONTAINER, | |
447 | .matchid = em->matchid, | |
448 | .flags = em->flags | |
449 | }; | |
450 | ||
add93b61 | 451 | NLA_PUT(skb, i+1, sizeof(em_hdr), &em_hdr); |
1da177e4 LT |
452 | |
453 | if (em->ops && em->ops->dump) { | |
454 | if (em->ops->dump(skb, em) < 0) | |
add93b61 | 455 | goto nla_put_failure; |
1da177e4 LT |
456 | } else if (tcf_em_is_container(em) || tcf_em_is_simple(em)) { |
457 | u32 u = em->data; | |
add93b61 | 458 | nla_put_nohdr(skb, sizeof(u), &u); |
1da177e4 | 459 | } else if (em->datalen > 0) |
add93b61 | 460 | nla_put_nohdr(skb, em->datalen, (void *) em->data); |
1da177e4 | 461 | |
27a884dc | 462 | tail = skb_tail_pointer(skb); |
add93b61 | 463 | match_start->nla_len = tail - (u8 *)match_start; |
1da177e4 LT |
464 | } |
465 | ||
4b3550ef PM |
466 | nla_nest_end(skb, list_start); |
467 | nla_nest_end(skb, top_start); | |
1da177e4 LT |
468 | |
469 | return 0; | |
470 | ||
add93b61 | 471 | nla_put_failure: |
1da177e4 LT |
472 | return -1; |
473 | } | |
62e3ba1b | 474 | EXPORT_SYMBOL(tcf_em_tree_dump); |
1da177e4 LT |
475 | |
476 | static inline int tcf_em_match(struct sk_buff *skb, struct tcf_ematch *em, | |
477 | struct tcf_pkt_info *info) | |
478 | { | |
479 | int r = em->ops->match(skb, em, info); | |
480 | return tcf_em_is_inverted(em) ? !r : r; | |
481 | } | |
482 | ||
483 | /* Do not use this function directly, use tcf_em_tree_match instead */ | |
484 | int __tcf_em_tree_match(struct sk_buff *skb, struct tcf_ematch_tree *tree, | |
485 | struct tcf_pkt_info *info) | |
486 | { | |
487 | int stackp = 0, match_idx = 0, res = 0; | |
488 | struct tcf_ematch *cur_match; | |
489 | int stack[CONFIG_NET_EMATCH_STACK]; | |
490 | ||
491 | proceed: | |
492 | while (match_idx < tree->hdr.nmatches) { | |
493 | cur_match = tcf_em_get_match(tree, match_idx); | |
494 | ||
495 | if (tcf_em_is_container(cur_match)) { | |
496 | if (unlikely(stackp >= CONFIG_NET_EMATCH_STACK)) | |
497 | goto stack_overflow; | |
498 | ||
499 | stack[stackp++] = match_idx; | |
500 | match_idx = cur_match->data; | |
501 | goto proceed; | |
502 | } | |
503 | ||
504 | res = tcf_em_match(skb, cur_match, info); | |
505 | ||
506 | if (tcf_em_early_end(cur_match, res)) | |
507 | break; | |
508 | ||
509 | match_idx++; | |
510 | } | |
511 | ||
512 | pop_stack: | |
513 | if (stackp > 0) { | |
514 | match_idx = stack[--stackp]; | |
515 | cur_match = tcf_em_get_match(tree, match_idx); | |
516 | ||
517 | if (tcf_em_early_end(cur_match, res)) | |
518 | goto pop_stack; | |
519 | else { | |
520 | match_idx++; | |
521 | goto proceed; | |
522 | } | |
523 | } | |
524 | ||
525 | return res; | |
526 | ||
527 | stack_overflow: | |
528 | if (net_ratelimit()) | |
529 | printk("Local stack overflow, increase NET_EMATCH_STACK\n"); | |
530 | return -1; | |
531 | } | |
1da177e4 | 532 | EXPORT_SYMBOL(__tcf_em_tree_match); |