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1/*
2 * Berkeley Packet Filter based traffic classifier
3 *
4 * Might be used to classify traffic through flexible, user-defined and
5 * possibly JIT-ed BPF filters for traffic control as an alternative to
6 * ematches.
7 *
8 * (C) 2013 Daniel Borkmann <dborkman@redhat.com>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 */
14
15#include <linux/module.h>
16#include <linux/types.h>
17#include <linux/skbuff.h>
18#include <linux/filter.h>
19#include <linux/bpf.h>
20
21#include <net/rtnetlink.h>
22#include <net/pkt_cls.h>
23#include <net/sock.h>
24
25MODULE_LICENSE("GPL");
26MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
27MODULE_DESCRIPTION("TC BPF based classifier");
28
29#define CLS_BPF_NAME_LEN 256
30
31struct cls_bpf_head {
32 struct list_head plist;
33 u32 hgen;
34 struct rcu_head rcu;
35};
36
37struct cls_bpf_prog {
38 struct bpf_prog *filter;
39 struct list_head link;
40 struct tcf_result res;
41 bool exts_integrated;
42 struct tcf_exts exts;
43 u32 handle;
44 union {
45 u32 bpf_fd;
46 u16 bpf_num_ops;
47 };
48 struct sock_filter *bpf_ops;
49 const char *bpf_name;
50 struct tcf_proto *tp;
51 struct rcu_head rcu;
52};
53
54static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = {
55 [TCA_BPF_CLASSID] = { .type = NLA_U32 },
56 [TCA_BPF_FLAGS] = { .type = NLA_U32 },
57 [TCA_BPF_FD] = { .type = NLA_U32 },
58 [TCA_BPF_NAME] = { .type = NLA_NUL_STRING, .len = CLS_BPF_NAME_LEN },
59 [TCA_BPF_OPS_LEN] = { .type = NLA_U16 },
60 [TCA_BPF_OPS] = { .type = NLA_BINARY,
61 .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
62};
63
64static int cls_bpf_exec_opcode(int code)
65{
66 switch (code) {
67 case TC_ACT_OK:
68 case TC_ACT_SHOT:
69 case TC_ACT_STOLEN:
70 case TC_ACT_REDIRECT:
71 case TC_ACT_UNSPEC:
72 return code;
73 default:
74 return TC_ACT_UNSPEC;
75 }
76}
77
78static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp,
79 struct tcf_result *res)
80{
81 struct cls_bpf_head *head = rcu_dereference_bh(tp->root);
82 bool at_ingress = skb_at_tc_ingress(skb);
83 struct cls_bpf_prog *prog;
84 int ret = -1;
85
86 if (unlikely(!skb_mac_header_was_set(skb)))
87 return -1;
88
89 /* Needed here for accessing maps. */
90 rcu_read_lock();
91 list_for_each_entry_rcu(prog, &head->plist, link) {
92 int filter_res;
93
94 qdisc_skb_cb(skb)->tc_classid = prog->res.classid;
95
96 if (at_ingress) {
97 /* It is safe to push/pull even if skb_shared() */
98 __skb_push(skb, skb->mac_len);
99 filter_res = BPF_PROG_RUN(prog->filter, skb);
100 __skb_pull(skb, skb->mac_len);
101 } else {
102 filter_res = BPF_PROG_RUN(prog->filter, skb);
103 }
104
105 if (prog->exts_integrated) {
106 res->class = 0;
107 res->classid = TC_H_MAJ(prog->res.classid) |
108 qdisc_skb_cb(skb)->tc_classid;
109
110 ret = cls_bpf_exec_opcode(filter_res);
111 if (ret == TC_ACT_UNSPEC)
112 continue;
113 break;
114 }
115
116 if (filter_res == 0)
117 continue;
118 if (filter_res != -1) {
119 res->class = 0;
120 res->classid = filter_res;
121 } else {
122 *res = prog->res;
123 }
124
125 ret = tcf_exts_exec(skb, &prog->exts, res);
126 if (ret < 0)
127 continue;
128
129 break;
130 }
131 rcu_read_unlock();
132
133 return ret;
134}
135
136static bool cls_bpf_is_ebpf(const struct cls_bpf_prog *prog)
137{
138 return !prog->bpf_ops;
139}
140
141static int cls_bpf_init(struct tcf_proto *tp)
142{
143 struct cls_bpf_head *head;
144
145 head = kzalloc(sizeof(*head), GFP_KERNEL);
146 if (head == NULL)
147 return -ENOBUFS;
148
149 INIT_LIST_HEAD_RCU(&head->plist);
150 rcu_assign_pointer(tp->root, head);
151
152 return 0;
153}
154
155static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog)
156{
157 tcf_exts_destroy(&prog->exts);
158
159 if (cls_bpf_is_ebpf(prog))
160 bpf_prog_put(prog->filter);
161 else
162 bpf_prog_destroy(prog->filter);
163
164 kfree(prog->bpf_name);
165 kfree(prog->bpf_ops);
166 kfree(prog);
167}
168
169static void __cls_bpf_delete_prog(struct rcu_head *rcu)
170{
171 struct cls_bpf_prog *prog = container_of(rcu, struct cls_bpf_prog, rcu);
172
173 cls_bpf_delete_prog(prog->tp, prog);
174}
175
176static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg)
177{
178 struct cls_bpf_prog *prog = (struct cls_bpf_prog *) arg;
179
180 list_del_rcu(&prog->link);
181 tcf_unbind_filter(tp, &prog->res);
182 call_rcu(&prog->rcu, __cls_bpf_delete_prog);
183
184 return 0;
185}
186
187static bool cls_bpf_destroy(struct tcf_proto *tp, bool force)
188{
189 struct cls_bpf_head *head = rtnl_dereference(tp->root);
190 struct cls_bpf_prog *prog, *tmp;
191
192 if (!force && !list_empty(&head->plist))
193 return false;
194
195 list_for_each_entry_safe(prog, tmp, &head->plist, link) {
196 list_del_rcu(&prog->link);
197 tcf_unbind_filter(tp, &prog->res);
198 call_rcu(&prog->rcu, __cls_bpf_delete_prog);
199 }
200
201 RCU_INIT_POINTER(tp->root, NULL);
202 kfree_rcu(head, rcu);
203 return true;
204}
205
206static unsigned long cls_bpf_get(struct tcf_proto *tp, u32 handle)
207{
208 struct cls_bpf_head *head = rtnl_dereference(tp->root);
209 struct cls_bpf_prog *prog;
210 unsigned long ret = 0UL;
211
212 if (head == NULL)
213 return 0UL;
214
215 list_for_each_entry(prog, &head->plist, link) {
216 if (prog->handle == handle) {
217 ret = (unsigned long) prog;
218 break;
219 }
220 }
221
222 return ret;
223}
224
225static int cls_bpf_prog_from_ops(struct nlattr **tb, struct cls_bpf_prog *prog)
226{
227 struct sock_filter *bpf_ops;
228 struct sock_fprog_kern fprog_tmp;
229 struct bpf_prog *fp;
230 u16 bpf_size, bpf_num_ops;
231 int ret;
232
233 bpf_num_ops = nla_get_u16(tb[TCA_BPF_OPS_LEN]);
234 if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0)
235 return -EINVAL;
236
237 bpf_size = bpf_num_ops * sizeof(*bpf_ops);
238 if (bpf_size != nla_len(tb[TCA_BPF_OPS]))
239 return -EINVAL;
240
241 bpf_ops = kzalloc(bpf_size, GFP_KERNEL);
242 if (bpf_ops == NULL)
243 return -ENOMEM;
244
245 memcpy(bpf_ops, nla_data(tb[TCA_BPF_OPS]), bpf_size);
246
247 fprog_tmp.len = bpf_num_ops;
248 fprog_tmp.filter = bpf_ops;
249
250 ret = bpf_prog_create(&fp, &fprog_tmp);
251 if (ret < 0) {
252 kfree(bpf_ops);
253 return ret;
254 }
255
256 prog->bpf_ops = bpf_ops;
257 prog->bpf_num_ops = bpf_num_ops;
258 prog->bpf_name = NULL;
259 prog->filter = fp;
260
261 return 0;
262}
263
264static int cls_bpf_prog_from_efd(struct nlattr **tb, struct cls_bpf_prog *prog,
265 const struct tcf_proto *tp)
266{
267 struct bpf_prog *fp;
268 char *name = NULL;
269 u32 bpf_fd;
270
271 bpf_fd = nla_get_u32(tb[TCA_BPF_FD]);
272
273 fp = bpf_prog_get(bpf_fd);
274 if (IS_ERR(fp))
275 return PTR_ERR(fp);
276
277 if (fp->type != BPF_PROG_TYPE_SCHED_CLS) {
278 bpf_prog_put(fp);
279 return -EINVAL;
280 }
281
282 if (tb[TCA_BPF_NAME]) {
283 name = kmemdup(nla_data(tb[TCA_BPF_NAME]),
284 nla_len(tb[TCA_BPF_NAME]),
285 GFP_KERNEL);
286 if (!name) {
287 bpf_prog_put(fp);
288 return -ENOMEM;
289 }
290 }
291
292 prog->bpf_ops = NULL;
293 prog->bpf_fd = bpf_fd;
294 prog->bpf_name = name;
295 prog->filter = fp;
296
297 if (fp->dst_needed && !(tp->q->flags & TCQ_F_INGRESS))
298 netif_keep_dst(qdisc_dev(tp->q));
299
300 return 0;
301}
302
303static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp,
304 struct cls_bpf_prog *prog,
305 unsigned long base, struct nlattr **tb,
306 struct nlattr *est, bool ovr)
307{
308 bool is_bpf, is_ebpf, have_exts = false;
309 struct tcf_exts exts;
310 int ret;
311
312 is_bpf = tb[TCA_BPF_OPS_LEN] && tb[TCA_BPF_OPS];
313 is_ebpf = tb[TCA_BPF_FD];
314 if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf))
315 return -EINVAL;
316
317 tcf_exts_init(&exts, TCA_BPF_ACT, TCA_BPF_POLICE);
318 ret = tcf_exts_validate(net, tp, tb, est, &exts, ovr);
319 if (ret < 0)
320 return ret;
321
322 if (tb[TCA_BPF_FLAGS]) {
323 u32 bpf_flags = nla_get_u32(tb[TCA_BPF_FLAGS]);
324
325 if (bpf_flags & ~TCA_BPF_FLAG_ACT_DIRECT) {
326 tcf_exts_destroy(&exts);
327 return -EINVAL;
328 }
329
330 have_exts = bpf_flags & TCA_BPF_FLAG_ACT_DIRECT;
331 }
332
333 prog->exts_integrated = have_exts;
334
335 ret = is_bpf ? cls_bpf_prog_from_ops(tb, prog) :
336 cls_bpf_prog_from_efd(tb, prog, tp);
337 if (ret < 0) {
338 tcf_exts_destroy(&exts);
339 return ret;
340 }
341
342 if (tb[TCA_BPF_CLASSID]) {
343 prog->res.classid = nla_get_u32(tb[TCA_BPF_CLASSID]);
344 tcf_bind_filter(tp, &prog->res, base);
345 }
346
347 tcf_exts_change(tp, &prog->exts, &exts);
348 return 0;
349}
350
351static u32 cls_bpf_grab_new_handle(struct tcf_proto *tp,
352 struct cls_bpf_head *head)
353{
354 unsigned int i = 0x80000000;
355 u32 handle;
356
357 do {
358 if (++head->hgen == 0x7FFFFFFF)
359 head->hgen = 1;
360 } while (--i > 0 && cls_bpf_get(tp, head->hgen));
361
362 if (unlikely(i == 0)) {
363 pr_err("Insufficient number of handles\n");
364 handle = 0;
365 } else {
366 handle = head->hgen;
367 }
368
369 return handle;
370}
371
372static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,
373 struct tcf_proto *tp, unsigned long base,
374 u32 handle, struct nlattr **tca,
375 unsigned long *arg, bool ovr)
376{
377 struct cls_bpf_head *head = rtnl_dereference(tp->root);
378 struct cls_bpf_prog *oldprog = (struct cls_bpf_prog *) *arg;
379 struct nlattr *tb[TCA_BPF_MAX + 1];
380 struct cls_bpf_prog *prog;
381 int ret;
382
383 if (tca[TCA_OPTIONS] == NULL)
384 return -EINVAL;
385
386 ret = nla_parse_nested(tb, TCA_BPF_MAX, tca[TCA_OPTIONS], bpf_policy);
387 if (ret < 0)
388 return ret;
389
390 prog = kzalloc(sizeof(*prog), GFP_KERNEL);
391 if (!prog)
392 return -ENOBUFS;
393
394 tcf_exts_init(&prog->exts, TCA_BPF_ACT, TCA_BPF_POLICE);
395
396 if (oldprog) {
397 if (handle && oldprog->handle != handle) {
398 ret = -EINVAL;
399 goto errout;
400 }
401 }
402
403 if (handle == 0)
404 prog->handle = cls_bpf_grab_new_handle(tp, head);
405 else
406 prog->handle = handle;
407 if (prog->handle == 0) {
408 ret = -EINVAL;
409 goto errout;
410 }
411
412 ret = cls_bpf_modify_existing(net, tp, prog, base, tb, tca[TCA_RATE], ovr);
413 if (ret < 0)
414 goto errout;
415
416 if (oldprog) {
417 list_replace_rcu(&oldprog->link, &prog->link);
418 tcf_unbind_filter(tp, &oldprog->res);
419 call_rcu(&oldprog->rcu, __cls_bpf_delete_prog);
420 } else {
421 list_add_rcu(&prog->link, &head->plist);
422 }
423
424 *arg = (unsigned long) prog;
425 return 0;
426errout:
427 kfree(prog);
428
429 return ret;
430}
431
432static int cls_bpf_dump_bpf_info(const struct cls_bpf_prog *prog,
433 struct sk_buff *skb)
434{
435 struct nlattr *nla;
436
437 if (nla_put_u16(skb, TCA_BPF_OPS_LEN, prog->bpf_num_ops))
438 return -EMSGSIZE;
439
440 nla = nla_reserve(skb, TCA_BPF_OPS, prog->bpf_num_ops *
441 sizeof(struct sock_filter));
442 if (nla == NULL)
443 return -EMSGSIZE;
444
445 memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
446
447 return 0;
448}
449
450static int cls_bpf_dump_ebpf_info(const struct cls_bpf_prog *prog,
451 struct sk_buff *skb)
452{
453 if (nla_put_u32(skb, TCA_BPF_FD, prog->bpf_fd))
454 return -EMSGSIZE;
455
456 if (prog->bpf_name &&
457 nla_put_string(skb, TCA_BPF_NAME, prog->bpf_name))
458 return -EMSGSIZE;
459
460 return 0;
461}
462
463static int cls_bpf_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
464 struct sk_buff *skb, struct tcmsg *tm)
465{
466 struct cls_bpf_prog *prog = (struct cls_bpf_prog *) fh;
467 struct nlattr *nest;
468 u32 bpf_flags = 0;
469 int ret;
470
471 if (prog == NULL)
472 return skb->len;
473
474 tm->tcm_handle = prog->handle;
475
476 nest = nla_nest_start(skb, TCA_OPTIONS);
477 if (nest == NULL)
478 goto nla_put_failure;
479
480 if (prog->res.classid &&
481 nla_put_u32(skb, TCA_BPF_CLASSID, prog->res.classid))
482 goto nla_put_failure;
483
484 if (cls_bpf_is_ebpf(prog))
485 ret = cls_bpf_dump_ebpf_info(prog, skb);
486 else
487 ret = cls_bpf_dump_bpf_info(prog, skb);
488 if (ret)
489 goto nla_put_failure;
490
491 if (tcf_exts_dump(skb, &prog->exts) < 0)
492 goto nla_put_failure;
493
494 if (prog->exts_integrated)
495 bpf_flags |= TCA_BPF_FLAG_ACT_DIRECT;
496 if (bpf_flags && nla_put_u32(skb, TCA_BPF_FLAGS, bpf_flags))
497 goto nla_put_failure;
498
499 nla_nest_end(skb, nest);
500
501 if (tcf_exts_dump_stats(skb, &prog->exts) < 0)
502 goto nla_put_failure;
503
504 return skb->len;
505
506nla_put_failure:
507 nla_nest_cancel(skb, nest);
508 return -1;
509}
510
511static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg)
512{
513 struct cls_bpf_head *head = rtnl_dereference(tp->root);
514 struct cls_bpf_prog *prog;
515
516 list_for_each_entry(prog, &head->plist, link) {
517 if (arg->count < arg->skip)
518 goto skip;
519 if (arg->fn(tp, (unsigned long) prog, arg) < 0) {
520 arg->stop = 1;
521 break;
522 }
523skip:
524 arg->count++;
525 }
526}
527
528static struct tcf_proto_ops cls_bpf_ops __read_mostly = {
529 .kind = "bpf",
530 .owner = THIS_MODULE,
531 .classify = cls_bpf_classify,
532 .init = cls_bpf_init,
533 .destroy = cls_bpf_destroy,
534 .get = cls_bpf_get,
535 .change = cls_bpf_change,
536 .delete = cls_bpf_delete,
537 .walk = cls_bpf_walk,
538 .dump = cls_bpf_dump,
539};
540
541static int __init cls_bpf_init_mod(void)
542{
543 return register_tcf_proto_ops(&cls_bpf_ops);
544}
545
546static void __exit cls_bpf_exit_mod(void)
547{
548 unregister_tcf_proto_ops(&cls_bpf_ops);
549}
550
551module_init(cls_bpf_init_mod);
552module_exit(cls_bpf_exit_mod);