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		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->mono_delivery_time))
58		skb->mono_delivery_time = 0;
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
94static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
95{
96	return !prog->bpf_ops;
97}
98
99static 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
117static 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
138static 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
171nla_put_failure:
172	spin_unlock_bh(&prog->tcf_lock);
173	nlmsg_trim(skb, tp);
174	return -1;
175}
176
177static 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
187static 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
224static 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
251static 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
266static 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
279static 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
377put_chain:
378	if (goto_ch)
379		tcf_chain_put_by_act(goto_ch);
380
381release_idr:
382	tcf_idr_release(*act, bind);
383	return ret;
384}
385
386static 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
394static 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};
404MODULE_ALIAS_NET_ACT("bpf");
405
406static __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
413static 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
418static 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
425static int __init bpf_init_module(void)
426{
427	return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
428}
429
430static void __exit bpf_cleanup_module(void)
431{
432	tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
433}
434
435module_init(bpf_init_module);
436module_exit(bpf_cleanup_module);
437
438MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
439MODULE_DESCRIPTION("TC BPF based action");
440MODULE_LICENSE("GPL v2");
441