1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (c) 2015 Jiri Pirko <jiri@resnulli.us>
4 */
5
6 #include <linux/module.h>
7 #include <linux/init.h>
8 #include <linux/kernel.h>
9 #include <linux/skbuff.h>
10 #include <linux/rtnetlink.h>
11 #include <linux/filter.h>
12 #include <linux/bpf.h>
13
14 #include <net/netlink.h>
15 #include <net/sock.h>
16 #include <net/pkt_sched.h>
17 #include <net/pkt_cls.h>
18
19 #include <linux/tc_act/tc_bpf.h>
20 #include <net/tc_act/tc_bpf.h>
21 #include <net/tc_wrapper.h>
22
23 #define ACT_BPF_NAME_LEN 256
24
25 struct tcf_bpf_cfg {
26 struct bpf_prog *filter;
27 struct sock_filter *bpf_ops;
28 const char *bpf_name;
29 u16 bpf_num_ops;
30 bool is_ebpf;
31 };
32
33 static struct tc_action_ops act_bpf_ops;
34
35 TC_INDIRECT_SCOPE int tcf_bpf_act(struct sk_buff *skb,
36 const struct tc_action *act,
37 struct tcf_result *res)
38 {
39 bool at_ingress = skb_at_tc_ingress(skb);
40 struct tcf_bpf *prog = to_bpf(act);
41 struct bpf_prog *filter;
42 int action, filter_res;
43
44 tcf_lastuse_update(&prog->tcf_tm);
45 bstats_update(this_cpu_ptr(prog->common.cpu_bstats), skb);
46
47 filter = rcu_dereference(prog->filter);
48 if (at_ingress) {
49 __skb_push(skb, skb->mac_len);
50 bpf_compute_data_pointers(skb);
51 filter_res = bpf_prog_run(filter, skb);
52 __skb_pull(skb, skb->mac_len);
53 } else {
54 bpf_compute_data_pointers(skb);
55 filter_res = bpf_prog_run(filter, skb);
56 }
57 if (unlikely(!skb->tstamp && skb->tstamp_type))
58 skb->tstamp_type = SKB_CLOCK_REALTIME;
59 if (skb_sk_is_prefetched(skb) && filter_res != TC_ACT_OK)
60 skb_orphan(skb);
61
62 /* A BPF program may overwrite the default action opcode.
63 * Similarly as in cls_bpf, if filter_res == -1 we use the
64 * default action specified from tc.
65 *
66 * In case a different well-known TC_ACT opcode has been
67 * returned, it will overwrite the default one.
68 *
69 * For everything else that is unknown, TC_ACT_UNSPEC is
70 * returned.
71 */
72 switch (filter_res) {
73 case TC_ACT_PIPE:
74 case TC_ACT_RECLASSIFY:
75 case TC_ACT_OK:
76 case TC_ACT_REDIRECT:
77 action = filter_res;
78 break;
79 case TC_ACT_SHOT:
80 action = filter_res;
81 qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats));
82 break;
83 case TC_ACT_UNSPEC:
84 action = prog->tcf_action;
85 break;
86 default:
87 action = TC_ACT_UNSPEC;
88 break;
89 }
90
91 return action;
92 }
93
94 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
95 {
96 return !prog->bpf_ops;
97 }
98
99 static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog,
100 struct sk_buff *skb)
101 {
102 struct nlattr *nla;
103
104 if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops))
105 return -EMSGSIZE;
106
107 nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops *
108 sizeof(struct sock_filter));
109 if (nla == NULL)
110 return -EMSGSIZE;
111
112 memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
113
114 return 0;
115 }
116
117 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
118 struct sk_buff *skb)
119 {
120 struct nlattr *nla;
121
122 if (prog->bpf_name &&
123 nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
124 return -EMSGSIZE;
125
126 if (nla_put_u32(skb, TCA_ACT_BPF_ID, prog->filter->aux->id))
127 return -EMSGSIZE;
128
129 nla = nla_reserve(skb, TCA_ACT_BPF_TAG, sizeof(prog->filter->tag));
130 if (nla == NULL)
131 return -EMSGSIZE;
132
133 memcpy(nla_data(nla), prog->filter->tag, nla_len(nla));
134
135 return 0;
136 }
137
138 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
139 int bind, int ref)
140 {
141 unsigned char *tp = skb_tail_pointer(skb);
142 struct tcf_bpf *prog = to_bpf(act);
143 struct tc_act_bpf opt = {
144 .index = prog->tcf_index,
145 .refcnt = refcount_read(&prog->tcf_refcnt) - ref,
146 .bindcnt = atomic_read(&prog->tcf_bindcnt) - bind,
147 };
148 struct tcf_t tm;
149 int ret;
150
151 spin_lock_bh(&prog->tcf_lock);
152 opt.action = prog->tcf_action;
153 if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
154 goto nla_put_failure;
155
156 if (tcf_bpf_is_ebpf(prog))
157 ret = tcf_bpf_dump_ebpf_info(prog, skb);
158 else
159 ret = tcf_bpf_dump_bpf_info(prog, skb);
160 if (ret)
161 goto nla_put_failure;
162
163 tcf_tm_dump(&tm, &prog->tcf_tm);
164 if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm,
165 TCA_ACT_BPF_PAD))
166 goto nla_put_failure;
167
168 spin_unlock_bh(&prog->tcf_lock);
169 return skb->len;
170
171 nla_put_failure:
172 spin_unlock_bh(&prog->tcf_lock);
173 nlmsg_trim(skb, tp);
174 return -1;
175 }
176
177 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
178 [TCA_ACT_BPF_PARMS] = { .len = sizeof(struct tc_act_bpf) },
179 [TCA_ACT_BPF_FD] = { .type = NLA_U32 },
180 [TCA_ACT_BPF_NAME] = { .type = NLA_NUL_STRING,
181 .len = ACT_BPF_NAME_LEN },
182 [TCA_ACT_BPF_OPS_LEN] = { .type = NLA_U16 },
183 [TCA_ACT_BPF_OPS] = { .type = NLA_BINARY,
184 .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
185 };
186
187 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
188 {
189 struct sock_filter *bpf_ops;
190 struct sock_fprog_kern fprog_tmp;
191 struct bpf_prog *fp;
192 u16 bpf_size, bpf_num_ops;
193 int ret;
194
195 bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
196 if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0)
197 return -EINVAL;
198
199 bpf_size = bpf_num_ops * sizeof(*bpf_ops);
200 if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
201 return -EINVAL;
202
203 bpf_ops = kmemdup(nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size, GFP_KERNEL);
204 if (bpf_ops == NULL)
205 return -ENOMEM;
206
207 fprog_tmp.len = bpf_num_ops;
208 fprog_tmp.filter = bpf_ops;
209
210 ret = bpf_prog_create(&fp, &fprog_tmp);
211 if (ret < 0) {
212 kfree(bpf_ops);
213 return ret;
214 }
215
216 cfg->bpf_ops = bpf_ops;
217 cfg->bpf_num_ops = bpf_num_ops;
218 cfg->filter = fp;
219 cfg->is_ebpf = false;
220
221 return 0;
222 }
223
224 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
225 {
226 struct bpf_prog *fp;
227 char *name = NULL;
228 u32 bpf_fd;
229
230 bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
231
232 fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT);
233 if (IS_ERR(fp))
234 return PTR_ERR(fp);
235
236 if (tb[TCA_ACT_BPF_NAME]) {
237 name = nla_memdup(tb[TCA_ACT_BPF_NAME], GFP_KERNEL);
238 if (!name) {
239 bpf_prog_put(fp);
240 return -ENOMEM;
241 }
242 }
243
244 cfg->bpf_name = name;
245 cfg->filter = fp;
246 cfg->is_ebpf = true;
247
248 return 0;
249 }
250
251 static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg)
252 {
253 struct bpf_prog *filter = cfg->filter;
254
255 if (filter) {
256 if (cfg->is_ebpf)
257 bpf_prog_put(filter);
258 else
259 bpf_prog_destroy(filter);
260 }
261
262 kfree(cfg->bpf_ops);
263 kfree(cfg->bpf_name);
264 }
265
266 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
267 struct tcf_bpf_cfg *cfg)
268 {
269 cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
270 /* updates to prog->filter are prevented, since it's called either
271 * with tcf lock or during final cleanup in rcu callback
272 */
273 cfg->filter = rcu_dereference_protected(prog->filter, 1);
274
275 cfg->bpf_ops = prog->bpf_ops;
276 cfg->bpf_name = prog->bpf_name;
277 }
278
279 static int tcf_bpf_init(struct net *net, struct nlattr *nla,
280 struct nlattr *est, struct tc_action **act,
281 struct tcf_proto *tp, u32 flags,
282 struct netlink_ext_ack *extack)
283 {
284 struct tc_action_net *tn = net_generic(net, act_bpf_ops.net_id);
285 bool bind = flags & TCA_ACT_FLAGS_BIND;
286 struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
287 struct tcf_chain *goto_ch = NULL;
288 struct tcf_bpf_cfg cfg, old;
289 struct tc_act_bpf *parm;
290 struct tcf_bpf *prog;
291 bool is_bpf, is_ebpf;
292 int ret, res = 0;
293 u32 index;
294
295 if (!nla)
296 return -EINVAL;
297
298 ret = nla_parse_nested_deprecated(tb, TCA_ACT_BPF_MAX, nla,
299 act_bpf_policy, NULL);
300 if (ret < 0)
301 return ret;
302
303 if (!tb[TCA_ACT_BPF_PARMS])
304 return -EINVAL;
305
306 parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
307 index = parm->index;
308 ret = tcf_idr_check_alloc(tn, &index, act, bind);
309 if (!ret) {
310 ret = tcf_idr_create(tn, index, est, act,
311 &act_bpf_ops, bind, true, flags);
312 if (ret < 0) {
313 tcf_idr_cleanup(tn, index);
314 return ret;
315 }
316
317 res = ACT_P_CREATED;
318 } else if (ret > 0) {
319 /* Don't override defaults. */
320 if (bind)
321 return ACT_P_BOUND;
322
323 if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
324 tcf_idr_release(*act, bind);
325 return -EEXIST;
326 }
327 } else {
328 return ret;
329 }
330
331 ret = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
332 if (ret < 0)
333 goto release_idr;
334
335 is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
336 is_ebpf = tb[TCA_ACT_BPF_FD];
337
338 if (is_bpf == is_ebpf) {
339 ret = -EINVAL;
340 goto put_chain;
341 }
342
343 memset(&cfg, 0, sizeof(cfg));
344
345 ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
346 tcf_bpf_init_from_efd(tb, &cfg);
347 if (ret < 0)
348 goto put_chain;
349
350 prog = to_bpf(*act);
351
352 spin_lock_bh(&prog->tcf_lock);
353 if (res != ACT_P_CREATED)
354 tcf_bpf_prog_fill_cfg(prog, &old);
355
356 prog->bpf_ops = cfg.bpf_ops;
357 prog->bpf_name = cfg.bpf_name;
358
359 if (cfg.bpf_num_ops)
360 prog->bpf_num_ops = cfg.bpf_num_ops;
361
362 goto_ch = tcf_action_set_ctrlact(*act, parm->action, goto_ch);
363 rcu_assign_pointer(prog->filter, cfg.filter);
364 spin_unlock_bh(&prog->tcf_lock);
365
366 if (goto_ch)
367 tcf_chain_put_by_act(goto_ch);
368
369 if (res != ACT_P_CREATED) {
370 /* make sure the program being replaced is no longer executing */
371 synchronize_rcu();
372 tcf_bpf_cfg_cleanup(&old);
373 }
374
375 return res;
376
377 put_chain:
378 if (goto_ch)
379 tcf_chain_put_by_act(goto_ch);
380
381 release_idr:
382 tcf_idr_release(*act, bind);
383 return ret;
384 }
385
386 static void tcf_bpf_cleanup(struct tc_action *act)
387 {
388 struct tcf_bpf_cfg tmp;
389
390 tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp);
391 tcf_bpf_cfg_cleanup(&tmp);
392 }
393
394 static struct tc_action_ops act_bpf_ops __read_mostly = {
395 .kind = "bpf",
396 .id = TCA_ID_BPF,
397 .owner = THIS_MODULE,
398 .act = tcf_bpf_act,
399 .dump = tcf_bpf_dump,
400 .cleanup = tcf_bpf_cleanup,
401 .init = tcf_bpf_init,
402 .size = sizeof(struct tcf_bpf),
403 };
404 MODULE_ALIAS_NET_ACT("bpf");
405
406 static __net_init int bpf_init_net(struct net *net)
407 {
408 struct tc_action_net *tn = net_generic(net, act_bpf_ops.net_id);
409
410 return tc_action_net_init(net, tn, &act_bpf_ops);
411 }
412
413 static void __net_exit bpf_exit_net(struct list_head *net_list)
414 {
415 tc_action_net_exit(net_list, act_bpf_ops.net_id);
416 }
417
418 static struct pernet_operations bpf_net_ops = {
419 .init = bpf_init_net,
420 .exit_batch = bpf_exit_net,
421 .id = &act_bpf_ops.net_id,
422 .size = sizeof(struct tc_action_net),
423 };
424
425 static int __init bpf_init_module(void)
426 {
427 return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
428 }
429
430 static void __exit bpf_cleanup_module(void)
431 {
432 tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
433 }
434
435 module_init(bpf_init_module);
436 module_exit(bpf_cleanup_module);
437
438 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
439 MODULE_DESCRIPTION("TC BPF based action");
440 MODULE_LICENSE("GPL v2");
441
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.