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