• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1 /*
2  * Copyright (c) 2015 Jiri Pirko <jiri@resnulli.us>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published by
6  * the Free Software Foundation; either version 2 of the License, or
7  * (at your option) any later version.
8  */
9 
10 #include <linux/module.h>
11 #include <linux/init.h>
12 #include <linux/kernel.h>
13 #include <linux/skbuff.h>
14 #include <linux/rtnetlink.h>
15 #include <linux/filter.h>
16 #include <linux/bpf.h>
17 
18 #include <net/netlink.h>
19 #include <net/pkt_sched.h>
20 
21 #include <linux/tc_act/tc_bpf.h>
22 #include <net/tc_act/tc_bpf.h>
23 
24 #define BPF_TAB_MASK		15
25 #define ACT_BPF_NAME_LEN	256
26 
27 struct tcf_bpf_cfg {
28 	struct bpf_prog *filter;
29 	struct sock_filter *bpf_ops;
30 	const char *bpf_name;
31 	u32 bpf_fd;
32 	u16 bpf_num_ops;
33 	bool is_ebpf;
34 };
35 
36 static int bpf_net_id;
37 static struct tc_action_ops act_bpf_ops;
38 
tcf_bpf(struct sk_buff * skb,const struct tc_action * act,struct tcf_result * res)39 static int tcf_bpf(struct sk_buff *skb, const struct tc_action *act,
40 		   struct tcf_result *res)
41 {
42 	bool at_ingress = skb_at_tc_ingress(skb);
43 	struct tcf_bpf *prog = to_bpf(act);
44 	struct bpf_prog *filter;
45 	int action, filter_res;
46 
47 	tcf_lastuse_update(&prog->tcf_tm);
48 	bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb);
49 
50 	rcu_read_lock();
51 	filter = rcu_dereference(prog->filter);
52 	if (at_ingress) {
53 		__skb_push(skb, skb->mac_len);
54 		bpf_compute_data_end(skb);
55 		filter_res = BPF_PROG_RUN(filter, skb);
56 		__skb_pull(skb, skb->mac_len);
57 	} else {
58 		bpf_compute_data_end(skb);
59 		filter_res = BPF_PROG_RUN(filter, skb);
60 	}
61 	rcu_read_unlock();
62 
63 	/* A BPF program may overwrite the default action opcode.
64 	 * Similarly as in cls_bpf, if filter_res == -1 we use the
65 	 * default action specified from tc.
66 	 *
67 	 * In case a different well-known TC_ACT opcode has been
68 	 * returned, it will overwrite the default one.
69 	 *
70 	 * For everything else that is unkown, TC_ACT_UNSPEC is
71 	 * returned.
72 	 */
73 	switch (filter_res) {
74 	case TC_ACT_PIPE:
75 	case TC_ACT_RECLASSIFY:
76 	case TC_ACT_OK:
77 	case TC_ACT_REDIRECT:
78 		action = filter_res;
79 		break;
80 	case TC_ACT_SHOT:
81 		action = filter_res;
82 		qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats));
83 		break;
84 	case TC_ACT_UNSPEC:
85 		action = prog->tcf_action;
86 		break;
87 	default:
88 		action = TC_ACT_UNSPEC;
89 		break;
90 	}
91 
92 	return action;
93 }
94 
tcf_bpf_is_ebpf(const struct tcf_bpf * prog)95 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
96 {
97 	return !prog->bpf_ops;
98 }
99 
tcf_bpf_dump_bpf_info(const struct tcf_bpf * prog,struct sk_buff * skb)100 static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog,
101 				 struct sk_buff *skb)
102 {
103 	struct nlattr *nla;
104 
105 	if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops))
106 		return -EMSGSIZE;
107 
108 	nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops *
109 			  sizeof(struct sock_filter));
110 	if (nla == NULL)
111 		return -EMSGSIZE;
112 
113 	memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
114 
115 	return 0;
116 }
117 
tcf_bpf_dump_ebpf_info(const struct tcf_bpf * prog,struct sk_buff * skb)118 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
119 				  struct sk_buff *skb)
120 {
121 	if (nla_put_u32(skb, TCA_ACT_BPF_FD, prog->bpf_fd))
122 		return -EMSGSIZE;
123 
124 	if (prog->bpf_name &&
125 	    nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
126 		return -EMSGSIZE;
127 
128 	return 0;
129 }
130 
tcf_bpf_dump(struct sk_buff * skb,struct tc_action * act,int bind,int ref)131 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
132 			int bind, int ref)
133 {
134 	unsigned char *tp = skb_tail_pointer(skb);
135 	struct tcf_bpf *prog = to_bpf(act);
136 	struct tc_act_bpf opt = {
137 		.index   = prog->tcf_index,
138 		.refcnt  = prog->tcf_refcnt - ref,
139 		.bindcnt = prog->tcf_bindcnt - bind,
140 		.action  = prog->tcf_action,
141 	};
142 	struct tcf_t tm;
143 	int ret;
144 
145 	if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
146 		goto nla_put_failure;
147 
148 	if (tcf_bpf_is_ebpf(prog))
149 		ret = tcf_bpf_dump_ebpf_info(prog, skb);
150 	else
151 		ret = tcf_bpf_dump_bpf_info(prog, skb);
152 	if (ret)
153 		goto nla_put_failure;
154 
155 	tcf_tm_dump(&tm, &prog->tcf_tm);
156 	if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm,
157 			  TCA_ACT_BPF_PAD))
158 		goto nla_put_failure;
159 
160 	return skb->len;
161 
162 nla_put_failure:
163 	nlmsg_trim(skb, tp);
164 	return -1;
165 }
166 
167 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
168 	[TCA_ACT_BPF_PARMS]	= { .len = sizeof(struct tc_act_bpf) },
169 	[TCA_ACT_BPF_FD]	= { .type = NLA_U32 },
170 	[TCA_ACT_BPF_NAME]	= { .type = NLA_NUL_STRING,
171 				    .len = ACT_BPF_NAME_LEN },
172 	[TCA_ACT_BPF_OPS_LEN]	= { .type = NLA_U16 },
173 	[TCA_ACT_BPF_OPS]	= { .type = NLA_BINARY,
174 				    .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
175 };
176 
tcf_bpf_init_from_ops(struct nlattr ** tb,struct tcf_bpf_cfg * cfg)177 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
178 {
179 	struct sock_filter *bpf_ops;
180 	struct sock_fprog_kern fprog_tmp;
181 	struct bpf_prog *fp;
182 	u16 bpf_size, bpf_num_ops;
183 	int ret;
184 
185 	bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
186 	if (bpf_num_ops	> BPF_MAXINSNS || bpf_num_ops == 0)
187 		return -EINVAL;
188 
189 	bpf_size = bpf_num_ops * sizeof(*bpf_ops);
190 	if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
191 		return -EINVAL;
192 
193 	bpf_ops = kzalloc(bpf_size, GFP_KERNEL);
194 	if (bpf_ops == NULL)
195 		return -ENOMEM;
196 
197 	memcpy(bpf_ops, nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size);
198 
199 	fprog_tmp.len = bpf_num_ops;
200 	fprog_tmp.filter = bpf_ops;
201 
202 	ret = bpf_prog_create(&fp, &fprog_tmp);
203 	if (ret < 0) {
204 		kfree(bpf_ops);
205 		return ret;
206 	}
207 
208 	cfg->bpf_ops = bpf_ops;
209 	cfg->bpf_num_ops = bpf_num_ops;
210 	cfg->filter = fp;
211 	cfg->is_ebpf = false;
212 
213 	return 0;
214 }
215 
tcf_bpf_init_from_efd(struct nlattr ** tb,struct tcf_bpf_cfg * cfg)216 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
217 {
218 	struct bpf_prog *fp;
219 	char *name = NULL;
220 	u32 bpf_fd;
221 
222 	bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
223 
224 	fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT);
225 	if (IS_ERR(fp))
226 		return PTR_ERR(fp);
227 
228 	if (tb[TCA_ACT_BPF_NAME]) {
229 		name = kmemdup(nla_data(tb[TCA_ACT_BPF_NAME]),
230 			       nla_len(tb[TCA_ACT_BPF_NAME]),
231 			       GFP_KERNEL);
232 		if (!name) {
233 			bpf_prog_put(fp);
234 			return -ENOMEM;
235 		}
236 	}
237 
238 	cfg->bpf_fd = bpf_fd;
239 	cfg->bpf_name = name;
240 	cfg->filter = fp;
241 	cfg->is_ebpf = true;
242 
243 	return 0;
244 }
245 
tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg * cfg)246 static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg)
247 {
248 	struct bpf_prog *filter = cfg->filter;
249 
250 	if (filter) {
251 		if (cfg->is_ebpf)
252 			bpf_prog_put(filter);
253 		else
254 			bpf_prog_destroy(filter);
255 	}
256 
257 	kfree(cfg->bpf_ops);
258 	kfree(cfg->bpf_name);
259 }
260 
tcf_bpf_prog_fill_cfg(const struct tcf_bpf * prog,struct tcf_bpf_cfg * cfg)261 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
262 				  struct tcf_bpf_cfg *cfg)
263 {
264 	cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
265 	/* updates to prog->filter are prevented, since it's called either
266 	 * with rtnl lock or during final cleanup in rcu callback
267 	 */
268 	cfg->filter = rcu_dereference_protected(prog->filter, 1);
269 
270 	cfg->bpf_ops = prog->bpf_ops;
271 	cfg->bpf_name = prog->bpf_name;
272 }
273 
tcf_bpf_init(struct net * net,struct nlattr * nla,struct nlattr * est,struct tc_action ** act,int replace,int bind)274 static int tcf_bpf_init(struct net *net, struct nlattr *nla,
275 			struct nlattr *est, struct tc_action **act,
276 			int replace, int bind)
277 {
278 	struct tc_action_net *tn = net_generic(net, bpf_net_id);
279 	struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
280 	struct tcf_bpf_cfg cfg, old;
281 	struct tc_act_bpf *parm;
282 	struct tcf_bpf *prog;
283 	bool is_bpf, is_ebpf;
284 	int ret, res = 0;
285 
286 	if (!nla)
287 		return -EINVAL;
288 
289 	ret = nla_parse_nested(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy);
290 	if (ret < 0)
291 		return ret;
292 
293 	if (!tb[TCA_ACT_BPF_PARMS])
294 		return -EINVAL;
295 
296 	parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
297 
298 	if (!tcf_hash_check(tn, parm->index, act, bind)) {
299 		ret = tcf_hash_create(tn, parm->index, est, act,
300 				      &act_bpf_ops, bind, true);
301 		if (ret < 0)
302 			return ret;
303 
304 		res = ACT_P_CREATED;
305 	} else {
306 		/* Don't override defaults. */
307 		if (bind)
308 			return 0;
309 
310 		tcf_hash_release(*act, bind);
311 		if (!replace)
312 			return -EEXIST;
313 	}
314 
315 	is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
316 	is_ebpf = tb[TCA_ACT_BPF_FD];
317 
318 	if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) {
319 		ret = -EINVAL;
320 		goto out;
321 	}
322 
323 	memset(&cfg, 0, sizeof(cfg));
324 
325 	ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
326 		       tcf_bpf_init_from_efd(tb, &cfg);
327 	if (ret < 0)
328 		goto out;
329 
330 	prog = to_bpf(*act);
331 	ASSERT_RTNL();
332 
333 	if (res != ACT_P_CREATED)
334 		tcf_bpf_prog_fill_cfg(prog, &old);
335 
336 	prog->bpf_ops = cfg.bpf_ops;
337 	prog->bpf_name = cfg.bpf_name;
338 
339 	if (cfg.bpf_num_ops)
340 		prog->bpf_num_ops = cfg.bpf_num_ops;
341 	if (cfg.bpf_fd)
342 		prog->bpf_fd = cfg.bpf_fd;
343 
344 	prog->tcf_action = parm->action;
345 	rcu_assign_pointer(prog->filter, cfg.filter);
346 
347 	if (res == ACT_P_CREATED) {
348 		tcf_hash_insert(tn, *act);
349 	} else {
350 		/* make sure the program being replaced is no longer executing */
351 		synchronize_rcu();
352 		tcf_bpf_cfg_cleanup(&old);
353 	}
354 
355 	return res;
356 out:
357 	if (res == ACT_P_CREATED)
358 		tcf_hash_cleanup(*act, est);
359 
360 	return ret;
361 }
362 
tcf_bpf_cleanup(struct tc_action * act,int bind)363 static void tcf_bpf_cleanup(struct tc_action *act, int bind)
364 {
365 	struct tcf_bpf_cfg tmp;
366 
367 	tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp);
368 	tcf_bpf_cfg_cleanup(&tmp);
369 }
370 
tcf_bpf_walker(struct net * net,struct sk_buff * skb,struct netlink_callback * cb,int type,const struct tc_action_ops * ops)371 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb,
372 			  struct netlink_callback *cb, int type,
373 			  const struct tc_action_ops *ops)
374 {
375 	struct tc_action_net *tn = net_generic(net, bpf_net_id);
376 
377 	return tcf_generic_walker(tn, skb, cb, type, ops);
378 }
379 
tcf_bpf_search(struct net * net,struct tc_action ** a,u32 index)380 static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index)
381 {
382 	struct tc_action_net *tn = net_generic(net, bpf_net_id);
383 
384 	return tcf_hash_search(tn, a, index);
385 }
386 
387 static struct tc_action_ops act_bpf_ops __read_mostly = {
388 	.kind		=	"bpf",
389 	.type		=	TCA_ACT_BPF,
390 	.owner		=	THIS_MODULE,
391 	.act		=	tcf_bpf,
392 	.dump		=	tcf_bpf_dump,
393 	.cleanup	=	tcf_bpf_cleanup,
394 	.init		=	tcf_bpf_init,
395 	.walk		=	tcf_bpf_walker,
396 	.lookup		=	tcf_bpf_search,
397 	.size		=	sizeof(struct tcf_bpf),
398 };
399 
bpf_init_net(struct net * net)400 static __net_init int bpf_init_net(struct net *net)
401 {
402 	struct tc_action_net *tn = net_generic(net, bpf_net_id);
403 
404 	return tc_action_net_init(tn, &act_bpf_ops, BPF_TAB_MASK);
405 }
406 
bpf_exit_net(struct net * net)407 static void __net_exit bpf_exit_net(struct net *net)
408 {
409 	struct tc_action_net *tn = net_generic(net, bpf_net_id);
410 
411 	tc_action_net_exit(tn);
412 }
413 
414 static struct pernet_operations bpf_net_ops = {
415 	.init = bpf_init_net,
416 	.exit = bpf_exit_net,
417 	.id   = &bpf_net_id,
418 	.size = sizeof(struct tc_action_net),
419 };
420 
bpf_init_module(void)421 static int __init bpf_init_module(void)
422 {
423 	return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
424 }
425 
bpf_cleanup_module(void)426 static void __exit bpf_cleanup_module(void)
427 {
428 	tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
429 }
430 
431 module_init(bpf_init_module);
432 module_exit(bpf_cleanup_module);
433 
434 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
435 MODULE_DESCRIPTION("TC BPF based action");
436 MODULE_LICENSE("GPL v2");
437