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
 24struct 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
 32static unsigned int bpf_net_id;
 33static struct tc_action_ops act_bpf_ops;
 34
 35static int tcf_bpf_act(struct sk_buff *skb, const struct tc_action *act,
 36		       struct tcf_result *res)
 37{
 38	bool at_ingress = skb_at_tc_ingress(skb);
 39	struct tcf_bpf *prog = to_bpf(act);
 40	struct bpf_prog *filter;
 41	int action, filter_res;
 42
 43	tcf_lastuse_update(&prog->tcf_tm);
 44	bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb);
 45
 46	filter = rcu_dereference(prog->filter);
 47	if (at_ingress) {
 48		__skb_push(skb, skb->mac_len);
 49		bpf_compute_data_pointers(skb);
 50		filter_res = BPF_PROG_RUN(filter, skb);
 51		__skb_pull(skb, skb->mac_len);
 52	} else {
 53		bpf_compute_data_pointers(skb);
 54		filter_res = BPF_PROG_RUN(filter, skb);
 55	}
 56	if (skb_sk_is_prefetched(skb) && filter_res != TC_ACT_OK)
 57		skb_orphan(skb);
 58
 59	/* A BPF program may overwrite the default action opcode.
 60	 * Similarly as in cls_bpf, if filter_res == -1 we use the
 61	 * default action specified from tc.
 62	 *
 63	 * In case a different well-known TC_ACT opcode has been
 64	 * returned, it will overwrite the default one.
 65	 *
 66	 * For everything else that is unknown, TC_ACT_UNSPEC is
 67	 * returned.
 68	 */
 69	switch (filter_res) {
 70	case TC_ACT_PIPE:
 71	case TC_ACT_RECLASSIFY:
 72	case TC_ACT_OK:
 73	case TC_ACT_REDIRECT:
 74		action = filter_res;
 75		break;
 76	case TC_ACT_SHOT:
 77		action = filter_res;
 78		qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats));
 79		break;
 80	case TC_ACT_UNSPEC:
 81		action = prog->tcf_action;
 82		break;
 83	default:
 84		action = TC_ACT_UNSPEC;
 85		break;
 86	}
 87
 88	return action;
 89}
 90
 91static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
 92{
 93	return !prog->bpf_ops;
 94}
 95
 96static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog,
 97				 struct sk_buff *skb)
 98{
 99	struct nlattr *nla;
100
101	if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops))
102		return -EMSGSIZE;
103
104	nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops *
105			  sizeof(struct sock_filter));
106	if (nla == NULL)
107		return -EMSGSIZE;
108
109	memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
110
111	return 0;
112}
113
114static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
115				  struct sk_buff *skb)
116{
117	struct nlattr *nla;
118
119	if (prog->bpf_name &&
120	    nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
121		return -EMSGSIZE;
122
123	if (nla_put_u32(skb, TCA_ACT_BPF_ID, prog->filter->aux->id))
124		return -EMSGSIZE;
125
126	nla = nla_reserve(skb, TCA_ACT_BPF_TAG, sizeof(prog->filter->tag));
127	if (nla == NULL)
128		return -EMSGSIZE;
129
130	memcpy(nla_data(nla), prog->filter->tag, nla_len(nla));
131
132	return 0;
133}
134
135static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
136			int bind, int ref)
137{
138	unsigned char *tp = skb_tail_pointer(skb);
139	struct tcf_bpf *prog = to_bpf(act);
140	struct tc_act_bpf opt = {
141		.index   = prog->tcf_index,
142		.refcnt  = refcount_read(&prog->tcf_refcnt) - ref,
143		.bindcnt = atomic_read(&prog->tcf_bindcnt) - bind,
144	};
145	struct tcf_t tm;
146	int ret;
147
148	spin_lock_bh(&prog->tcf_lock);
149	opt.action = prog->tcf_action;
150	if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
151		goto nla_put_failure;
152
153	if (tcf_bpf_is_ebpf(prog))
154		ret = tcf_bpf_dump_ebpf_info(prog, skb);
155	else
156		ret = tcf_bpf_dump_bpf_info(prog, skb);
157	if (ret)
158		goto nla_put_failure;
159
160	tcf_tm_dump(&tm, &prog->tcf_tm);
161	if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm,
162			  TCA_ACT_BPF_PAD))
163		goto nla_put_failure;
164
165	spin_unlock_bh(&prog->tcf_lock);
166	return skb->len;
167
168nla_put_failure:
169	spin_unlock_bh(&prog->tcf_lock);
170	nlmsg_trim(skb, tp);
171	return -1;
172}
173
174static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
175	[TCA_ACT_BPF_PARMS]	= { .len = sizeof(struct tc_act_bpf) },
176	[TCA_ACT_BPF_FD]	= { .type = NLA_U32 },
177	[TCA_ACT_BPF_NAME]	= { .type = NLA_NUL_STRING,
178				    .len = ACT_BPF_NAME_LEN },
179	[TCA_ACT_BPF_OPS_LEN]	= { .type = NLA_U16 },
180	[TCA_ACT_BPF_OPS]	= { .type = NLA_BINARY,
181				    .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
182};
183
184static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
185{
186	struct sock_filter *bpf_ops;
187	struct sock_fprog_kern fprog_tmp;
188	struct bpf_prog *fp;
189	u16 bpf_size, bpf_num_ops;
190	int ret;
191
192	bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
193	if (bpf_num_ops	> BPF_MAXINSNS || bpf_num_ops == 0)
194		return -EINVAL;
195
196	bpf_size = bpf_num_ops * sizeof(*bpf_ops);
197	if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
198		return -EINVAL;
199
200	bpf_ops = kmemdup(nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size, GFP_KERNEL);
201	if (bpf_ops == NULL)
202		return -ENOMEM;
203
204	fprog_tmp.len = bpf_num_ops;
205	fprog_tmp.filter = bpf_ops;
206
207	ret = bpf_prog_create(&fp, &fprog_tmp);
208	if (ret < 0) {
209		kfree(bpf_ops);
210		return ret;
211	}
212
213	cfg->bpf_ops = bpf_ops;
214	cfg->bpf_num_ops = bpf_num_ops;
215	cfg->filter = fp;
216	cfg->is_ebpf = false;
217
218	return 0;
219}
220
221static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
222{
223	struct bpf_prog *fp;
224	char *name = NULL;
225	u32 bpf_fd;
226
227	bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
228
229	fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT);
230	if (IS_ERR(fp))
231		return PTR_ERR(fp);
232
233	if (tb[TCA_ACT_BPF_NAME]) {
234		name = nla_memdup(tb[TCA_ACT_BPF_NAME], GFP_KERNEL);
235		if (!name) {
236			bpf_prog_put(fp);
237			return -ENOMEM;
238		}
239	}
240
241	cfg->bpf_name = name;
242	cfg->filter = fp;
243	cfg->is_ebpf = true;
244
245	return 0;
246}
247
248static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg)
249{
250	struct bpf_prog *filter = cfg->filter;
251
252	if (filter) {
253		if (cfg->is_ebpf)
254			bpf_prog_put(filter);
255		else
256			bpf_prog_destroy(filter);
257	}
258
259	kfree(cfg->bpf_ops);
260	kfree(cfg->bpf_name);
261}
262
263static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
264				  struct tcf_bpf_cfg *cfg)
265{
266	cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
267	/* updates to prog->filter are prevented, since it's called either
268	 * with tcf lock or during final cleanup in rcu callback
269	 */
270	cfg->filter = rcu_dereference_protected(prog->filter, 1);
271
272	cfg->bpf_ops = prog->bpf_ops;
273	cfg->bpf_name = prog->bpf_name;
274}
275
276static int tcf_bpf_init(struct net *net, struct nlattr *nla,
277			struct nlattr *est, struct tc_action **act,
278			int replace, int bind, bool rtnl_held,
279			struct tcf_proto *tp, u32 flags,
280			struct netlink_ext_ack *extack)
281{
282	struct tc_action_net *tn = net_generic(net, bpf_net_id);
283	struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
284	struct tcf_chain *goto_ch = NULL;
285	struct tcf_bpf_cfg cfg, old;
286	struct tc_act_bpf *parm;
287	struct tcf_bpf *prog;
288	bool is_bpf, is_ebpf;
289	int ret, res = 0;
290	u32 index;
291
292	if (!nla)
293		return -EINVAL;
294
295	ret = nla_parse_nested_deprecated(tb, TCA_ACT_BPF_MAX, nla,
296					  act_bpf_policy, NULL);
297	if (ret < 0)
298		return ret;
299
300	if (!tb[TCA_ACT_BPF_PARMS])
301		return -EINVAL;
302
303	parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
304	index = parm->index;
305	ret = tcf_idr_check_alloc(tn, &index, act, bind);
306	if (!ret) {
307		ret = tcf_idr_create(tn, index, est, act,
308				     &act_bpf_ops, bind, true, 0);
309		if (ret < 0) {
310			tcf_idr_cleanup(tn, index);
311			return ret;
312		}
313
314		res = ACT_P_CREATED;
315	} else if (ret > 0) {
316		/* Don't override defaults. */
317		if (bind)
318			return 0;
319
320		if (!replace) {
321			tcf_idr_release(*act, bind);
322			return -EEXIST;
323		}
324	} else {
325		return ret;
326	}
327
328	ret = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
329	if (ret < 0)
330		goto release_idr;
331
332	is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
333	is_ebpf = tb[TCA_ACT_BPF_FD];
334
335	if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) {
336		ret = -EINVAL;
337		goto put_chain;
338	}
339
340	memset(&cfg, 0, sizeof(cfg));
341
342	ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
343		       tcf_bpf_init_from_efd(tb, &cfg);
344	if (ret < 0)
345		goto put_chain;
346
347	prog = to_bpf(*act);
348
349	spin_lock_bh(&prog->tcf_lock);
350	if (res != ACT_P_CREATED)
351		tcf_bpf_prog_fill_cfg(prog, &old);
352
353	prog->bpf_ops = cfg.bpf_ops;
354	prog->bpf_name = cfg.bpf_name;
355
356	if (cfg.bpf_num_ops)
357		prog->bpf_num_ops = cfg.bpf_num_ops;
358
359	goto_ch = tcf_action_set_ctrlact(*act, parm->action, goto_ch);
360	rcu_assign_pointer(prog->filter, cfg.filter);
361	spin_unlock_bh(&prog->tcf_lock);
362
363	if (goto_ch)
364		tcf_chain_put_by_act(goto_ch);
365
366	if (res != ACT_P_CREATED) {
367		/* make sure the program being replaced is no longer executing */
368		synchronize_rcu();
369		tcf_bpf_cfg_cleanup(&old);
370	}
371
372	return res;
373
374put_chain:
375	if (goto_ch)
376		tcf_chain_put_by_act(goto_ch);
377
378release_idr:
379	tcf_idr_release(*act, bind);
380	return ret;
381}
382
383static void tcf_bpf_cleanup(struct tc_action *act)
384{
385	struct tcf_bpf_cfg tmp;
386
387	tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp);
388	tcf_bpf_cfg_cleanup(&tmp);
389}
390
391static int tcf_bpf_walker(struct net *net, struct sk_buff *skb,
392			  struct netlink_callback *cb, int type,
393			  const struct tc_action_ops *ops,
394			  struct netlink_ext_ack *extack)
395{
396	struct tc_action_net *tn = net_generic(net, bpf_net_id);
397
398	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
399}
400
401static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index)
402{
403	struct tc_action_net *tn = net_generic(net, bpf_net_id);
404
405	return tcf_idr_search(tn, a, index);
406}
407
408static struct tc_action_ops act_bpf_ops __read_mostly = {
409	.kind		=	"bpf",
410	.id		=	TCA_ID_BPF,
411	.owner		=	THIS_MODULE,
412	.act		=	tcf_bpf_act,
413	.dump		=	tcf_bpf_dump,
414	.cleanup	=	tcf_bpf_cleanup,
415	.init		=	tcf_bpf_init,
416	.walk		=	tcf_bpf_walker,
417	.lookup		=	tcf_bpf_search,
418	.size		=	sizeof(struct tcf_bpf),
419};
420
421static __net_init int bpf_init_net(struct net *net)
422{
423	struct tc_action_net *tn = net_generic(net, bpf_net_id);
424
425	return tc_action_net_init(net, tn, &act_bpf_ops);
426}
427
428static void __net_exit bpf_exit_net(struct list_head *net_list)
429{
430	tc_action_net_exit(net_list, bpf_net_id);
431}
432
433static struct pernet_operations bpf_net_ops = {
434	.init = bpf_init_net,
435	.exit_batch = bpf_exit_net,
436	.id   = &bpf_net_id,
437	.size = sizeof(struct tc_action_net),
438};
439
440static int __init bpf_init_module(void)
441{
442	return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
443}
444
445static void __exit bpf_cleanup_module(void)
446{
447	tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
448}
449
450module_init(bpf_init_module);
451module_exit(bpf_cleanup_module);
452
453MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
454MODULE_DESCRIPTION("TC BPF based action");
455MODULE_LICENSE("GPL v2");