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/pkt_sched.h>
 16#include <net/pkt_cls.h>
 17
 18#include <linux/tc_act/tc_bpf.h>
 19#include <net/tc_act/tc_bpf.h>
 20
 21#define ACT_BPF_NAME_LEN	256
 22
 23struct tcf_bpf_cfg {
 24	struct bpf_prog *filter;
 25	struct sock_filter *bpf_ops;
 26	const char *bpf_name;
 27	u16 bpf_num_ops;
 28	bool is_ebpf;
 29};
 30
 31static unsigned int bpf_net_id;
 32static struct tc_action_ops act_bpf_ops;
 33
 34static 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_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb);
 44
 45	rcu_read_lock();
 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	rcu_read_unlock();
 57
 58	/* A BPF program may overwrite the default action opcode.
 59	 * Similarly as in cls_bpf, if filter_res == -1 we use the
 60	 * default action specified from tc.
 61	 *
 62	 * In case a different well-known TC_ACT opcode has been
 63	 * returned, it will overwrite the default one.
 64	 *
 65	 * For everything else that is unkown, TC_ACT_UNSPEC is
 66	 * returned.
 67	 */
 68	switch (filter_res) {
 69	case TC_ACT_PIPE:
 70	case TC_ACT_RECLASSIFY:
 71	case TC_ACT_OK:
 72	case TC_ACT_REDIRECT:
 73		action = filter_res;
 74		break;
 75	case TC_ACT_SHOT:
 76		action = filter_res;
 77		qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats));
 78		break;
 79	case TC_ACT_UNSPEC:
 80		action = prog->tcf_action;
 81		break;
 82	default:
 83		action = TC_ACT_UNSPEC;
 84		break;
 85	}
 86
 87	return action;
 88}
 89
 90static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
 91{
 92	return !prog->bpf_ops;
 93}
 94
 95static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog,
 96				 struct sk_buff *skb)
 97{
 98	struct nlattr *nla;
 99
100	if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops))
101		return -EMSGSIZE;
102
103	nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops *
104			  sizeof(struct sock_filter));
105	if (nla == NULL)
106		return -EMSGSIZE;
107
108	memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
109
110	return 0;
111}
112
113static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
114				  struct sk_buff *skb)
115{
116	struct nlattr *nla;
117
118	if (prog->bpf_name &&
119	    nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
120		return -EMSGSIZE;
121
122	if (nla_put_u32(skb, TCA_ACT_BPF_ID, prog->filter->aux->id))
123		return -EMSGSIZE;
124
125	nla = nla_reserve(skb, TCA_ACT_BPF_TAG, sizeof(prog->filter->tag));
126	if (nla == NULL)
127		return -EMSGSIZE;
128
129	memcpy(nla_data(nla), prog->filter->tag, nla_len(nla));
130
131	return 0;
132}
133
134static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
135			int bind, int ref)
136{
137	unsigned char *tp = skb_tail_pointer(skb);
138	struct tcf_bpf *prog = to_bpf(act);
139	struct tc_act_bpf opt = {
140		.index   = prog->tcf_index,
141		.refcnt  = refcount_read(&prog->tcf_refcnt) - ref,
142		.bindcnt = atomic_read(&prog->tcf_bindcnt) - bind,
143	};
144	struct tcf_t tm;
145	int ret;
146
147	spin_lock_bh(&prog->tcf_lock);
148	opt.action = prog->tcf_action;
149	if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
150		goto nla_put_failure;
151
152	if (tcf_bpf_is_ebpf(prog))
153		ret = tcf_bpf_dump_ebpf_info(prog, skb);
154	else
155		ret = tcf_bpf_dump_bpf_info(prog, skb);
156	if (ret)
157		goto nla_put_failure;
158
159	tcf_tm_dump(&tm, &prog->tcf_tm);
160	if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm,
161			  TCA_ACT_BPF_PAD))
162		goto nla_put_failure;
163
164	spin_unlock_bh(&prog->tcf_lock);
165	return skb->len;
166
167nla_put_failure:
168	spin_unlock_bh(&prog->tcf_lock);
169	nlmsg_trim(skb, tp);
170	return -1;
171}
172
173static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
174	[TCA_ACT_BPF_PARMS]	= { .len = sizeof(struct tc_act_bpf) },
175	[TCA_ACT_BPF_FD]	= { .type = NLA_U32 },
176	[TCA_ACT_BPF_NAME]	= { .type = NLA_NUL_STRING,
177				    .len = ACT_BPF_NAME_LEN },
178	[TCA_ACT_BPF_OPS_LEN]	= { .type = NLA_U16 },
179	[TCA_ACT_BPF_OPS]	= { .type = NLA_BINARY,
180				    .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
181};
182
183static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
184{
185	struct sock_filter *bpf_ops;
186	struct sock_fprog_kern fprog_tmp;
187	struct bpf_prog *fp;
188	u16 bpf_size, bpf_num_ops;
189	int ret;
190
191	bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
192	if (bpf_num_ops	> BPF_MAXINSNS || bpf_num_ops == 0)
193		return -EINVAL;
194
195	bpf_size = bpf_num_ops * sizeof(*bpf_ops);
196	if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
197		return -EINVAL;
198
199	bpf_ops = kmemdup(nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size, GFP_KERNEL);
200	if (bpf_ops == NULL)
201		return -ENOMEM;
202
203	fprog_tmp.len = bpf_num_ops;
204	fprog_tmp.filter = bpf_ops;
205
206	ret = bpf_prog_create(&fp, &fprog_tmp);
207	if (ret < 0) {
208		kfree(bpf_ops);
209		return ret;
210	}
211
212	cfg->bpf_ops = bpf_ops;
213	cfg->bpf_num_ops = bpf_num_ops;
214	cfg->filter = fp;
215	cfg->is_ebpf = false;
216
217	return 0;
218}
219
220static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
221{
222	struct bpf_prog *fp;
223	char *name = NULL;
224	u32 bpf_fd;
225
226	bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
227
228	fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT);
229	if (IS_ERR(fp))
230		return PTR_ERR(fp);
231
232	if (tb[TCA_ACT_BPF_NAME]) {
233		name = nla_memdup(tb[TCA_ACT_BPF_NAME], GFP_KERNEL);
234		if (!name) {
235			bpf_prog_put(fp);
236			return -ENOMEM;
237		}
238	}
239
240	cfg->bpf_name = name;
241	cfg->filter = fp;
242	cfg->is_ebpf = true;
243
244	return 0;
245}
246
247static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg)
248{
249	struct bpf_prog *filter = cfg->filter;
250
251	if (filter) {
252		if (cfg->is_ebpf)
253			bpf_prog_put(filter);
254		else
255			bpf_prog_destroy(filter);
256	}
257
258	kfree(cfg->bpf_ops);
259	kfree(cfg->bpf_name);
260}
261
262static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
263				  struct tcf_bpf_cfg *cfg)
264{
265	cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
266	/* updates to prog->filter are prevented, since it's called either
267	 * with tcf lock or during final cleanup in rcu callback
268	 */
269	cfg->filter = rcu_dereference_protected(prog->filter, 1);
270
271	cfg->bpf_ops = prog->bpf_ops;
272	cfg->bpf_name = prog->bpf_name;
273}
274
275static int tcf_bpf_init(struct net *net, struct nlattr *nla,
276			struct nlattr *est, struct tc_action **act,
277			int replace, int bind, bool rtnl_held,
278			struct tcf_proto *tp, struct netlink_ext_ack *extack)
279{
280	struct tc_action_net *tn = net_generic(net, bpf_net_id);
281	struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
282	struct tcf_chain *goto_ch = NULL;
283	struct tcf_bpf_cfg cfg, old;
284	struct tc_act_bpf *parm;
285	struct tcf_bpf *prog;
286	bool is_bpf, is_ebpf;
287	int ret, res = 0;
288	u32 index;
289
290	if (!nla)
291		return -EINVAL;
292
293	ret = nla_parse_nested_deprecated(tb, TCA_ACT_BPF_MAX, nla,
294					  act_bpf_policy, NULL);
295	if (ret < 0)
296		return ret;
297
298	if (!tb[TCA_ACT_BPF_PARMS])
299		return -EINVAL;
300
301	parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
302	index = parm->index;
303	ret = tcf_idr_check_alloc(tn, &index, act, bind);
304	if (!ret) {
305		ret = tcf_idr_create(tn, index, est, act,
306				     &act_bpf_ops, bind, true);
307		if (ret < 0) {
308			tcf_idr_cleanup(tn, index);
309			return ret;
310		}
311
312		res = ACT_P_CREATED;
313	} else if (ret > 0) {
314		/* Don't override defaults. */
315		if (bind)
316			return 0;
317
318		if (!replace) {
319			tcf_idr_release(*act, bind);
320			return -EEXIST;
321		}
322	} else {
323		return ret;
324	}
325
326	ret = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
327	if (ret < 0)
328		goto release_idr;
329
330	is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
331	is_ebpf = tb[TCA_ACT_BPF_FD];
332
333	if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) {
334		ret = -EINVAL;
335		goto put_chain;
336	}
337
338	memset(&cfg, 0, sizeof(cfg));
339
340	ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
341		       tcf_bpf_init_from_efd(tb, &cfg);
342	if (ret < 0)
343		goto put_chain;
344
345	prog = to_bpf(*act);
346
347	spin_lock_bh(&prog->tcf_lock);
348	if (res != ACT_P_CREATED)
349		tcf_bpf_prog_fill_cfg(prog, &old);
350
351	prog->bpf_ops = cfg.bpf_ops;
352	prog->bpf_name = cfg.bpf_name;
353
354	if (cfg.bpf_num_ops)
355		prog->bpf_num_ops = cfg.bpf_num_ops;
356
357	goto_ch = tcf_action_set_ctrlact(*act, parm->action, goto_ch);
358	rcu_assign_pointer(prog->filter, cfg.filter);
359	spin_unlock_bh(&prog->tcf_lock);
360
361	if (goto_ch)
362		tcf_chain_put_by_act(goto_ch);
363
364	if (res == ACT_P_CREATED) {
365		tcf_idr_insert(tn, *act);
366	} else {
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");