act_bpf.c

  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
 25struct 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
 33static struct tc_action_ops act_bpf_ops;
 34
 35TC_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		filter_res = bpf_prog_run_data_pointers(filter, skb);
 51		__skb_pull(skb, skb->mac_len);
 52	} else {
 53		filter_res = bpf_prog_run_data_pointers(filter, skb);
 54	}
 55	if (unlikely(!skb->tstamp && skb->tstamp_type))
 56		skb->tstamp_type = SKB_CLOCK_REALTIME;
 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
 92static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
 93{
 94	return !prog->bpf_ops;
 95}
 96
 97static 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
115static 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
136static 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
169nla_put_failure:
170	spin_unlock_bh(&prog->tcf_lock);
171	nlmsg_trim(skb, tp);
172	return -1;
173}
174
175static 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
185static 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
222static 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
249static 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
264static 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
277static 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 ACT_P_BOUND;
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
375put_chain:
376	if (goto_ch)
377		tcf_chain_put_by_act(goto_ch);
378
379release_idr:
380	tcf_idr_release(*act, bind);
381	return ret;
382}
383
384static 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
392static 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};
402MODULE_ALIAS_NET_ACT("bpf");
403
404static __net_init int bpf_init_net(struct net *net)
405{
406	struct tc_action_net *tn = net_generic(net, act_bpf_ops.net_id);
407
408	return tc_action_net_init(net, tn, &act_bpf_ops);
409}
410
411static void __net_exit bpf_exit_net(struct list_head *net_list)
412{
413	tc_action_net_exit(net_list, act_bpf_ops.net_id);
414}
415
416static struct pernet_operations bpf_net_ops = {
417	.init = bpf_init_net,
418	.exit_batch = bpf_exit_net,
419	.id   = &act_bpf_ops.net_id,
420	.size = sizeof(struct tc_action_net),
421};
422
423static int __init bpf_init_module(void)
424{
425	return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
426}
427
428static void __exit bpf_cleanup_module(void)
429{
430	tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
431}
432
433module_init(bpf_init_module);
434module_exit(bpf_cleanup_module);
435
436MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
437MODULE_DESCRIPTION("TC BPF based action");
438MODULE_LICENSE("GPL v2");