xref: /linux/net/sched/act_bpf.c (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
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 
tcf_bpf_act(struct sk_buff * skb,const struct tc_action * act,struct tcf_result * res)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 
tcf_bpf_is_ebpf(const struct tcf_bpf * prog)94 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
95 {
96 	return !prog->bpf_ops;
97 }
98 
tcf_bpf_dump_bpf_info(const struct tcf_bpf * prog,struct sk_buff * skb)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 
tcf_bpf_dump_ebpf_info(const struct tcf_bpf * prog,struct sk_buff * skb)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 
tcf_bpf_dump(struct sk_buff * skb,struct tc_action * act,int bind,int ref)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 
tcf_bpf_init_from_ops(struct nlattr ** tb,struct tcf_bpf_cfg * cfg)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 
tcf_bpf_init_from_efd(struct nlattr ** tb,struct tcf_bpf_cfg * cfg)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 
tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg * cfg)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 
tcf_bpf_prog_fill_cfg(const struct tcf_bpf * prog,struct tcf_bpf_cfg * cfg)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 
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)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 
tcf_bpf_cleanup(struct tc_action * act)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 
bpf_init_net(struct net * net)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 
bpf_exit_net(struct list_head * net_list)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 
bpf_init_module(void)425 static int __init bpf_init_module(void)
426 {
427 	return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
428 }
429 
bpf_cleanup_module(void)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