GNU Linux-libre 4.19.211-gnu1
[releases.git] / net / sched / act_bpf.c
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 ACT_BPF_NAME_LEN        256
25
26 struct tcf_bpf_cfg {
27         struct bpf_prog *filter;
28         struct sock_filter *bpf_ops;
29         const char *bpf_name;
30         u16 bpf_num_ops;
31         bool is_ebpf;
32 };
33
34 static unsigned int bpf_net_id;
35 static struct tc_action_ops act_bpf_ops;
36
37 static int tcf_bpf_act(struct sk_buff *skb, const struct tc_action *act,
38                        struct tcf_result *res)
39 {
40         bool at_ingress = skb_at_tc_ingress(skb);
41         struct tcf_bpf *prog = to_bpf(act);
42         struct bpf_prog *filter;
43         int action, filter_res;
44
45         tcf_lastuse_update(&prog->tcf_tm);
46         bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb);
47
48         rcu_read_lock();
49         filter = rcu_dereference(prog->filter);
50         if (at_ingress) {
51                 __skb_push(skb, skb->mac_len);
52                 bpf_compute_data_pointers(skb);
53                 filter_res = BPF_PROG_RUN(filter, skb);
54                 __skb_pull(skb, skb->mac_len);
55         } else {
56                 bpf_compute_data_pointers(skb);
57                 filter_res = BPF_PROG_RUN(filter, skb);
58         }
59         rcu_read_unlock();
60
61         /* A BPF program may overwrite the default action opcode.
62          * Similarly as in cls_bpf, if filter_res == -1 we use the
63          * default action specified from tc.
64          *
65          * In case a different well-known TC_ACT opcode has been
66          * returned, it will overwrite the default one.
67          *
68          * For everything else that is unkown, TC_ACT_UNSPEC is
69          * returned.
70          */
71         switch (filter_res) {
72         case TC_ACT_PIPE:
73         case TC_ACT_RECLASSIFY:
74         case TC_ACT_OK:
75         case TC_ACT_REDIRECT:
76                 action = filter_res;
77                 break;
78         case TC_ACT_SHOT:
79                 action = filter_res;
80                 qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats));
81                 break;
82         case TC_ACT_UNSPEC:
83                 action = prog->tcf_action;
84                 break;
85         default:
86                 action = TC_ACT_UNSPEC;
87                 break;
88         }
89
90         return action;
91 }
92
93 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
94 {
95         return !prog->bpf_ops;
96 }
97
98 static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog,
99                                  struct sk_buff *skb)
100 {
101         struct nlattr *nla;
102
103         if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops))
104                 return -EMSGSIZE;
105
106         nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops *
107                           sizeof(struct sock_filter));
108         if (nla == NULL)
109                 return -EMSGSIZE;
110
111         memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
112
113         return 0;
114 }
115
116 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
117                                   struct sk_buff *skb)
118 {
119         struct nlattr *nla;
120
121         if (prog->bpf_name &&
122             nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
123                 return -EMSGSIZE;
124
125         if (nla_put_u32(skb, TCA_ACT_BPF_ID, prog->filter->aux->id))
126                 return -EMSGSIZE;
127
128         nla = nla_reserve(skb, TCA_ACT_BPF_TAG, sizeof(prog->filter->tag));
129         if (nla == NULL)
130                 return -EMSGSIZE;
131
132         memcpy(nla_data(nla), prog->filter->tag, nla_len(nla));
133
134         return 0;
135 }
136
137 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
138                         int bind, int ref)
139 {
140         unsigned char *tp = skb_tail_pointer(skb);
141         struct tcf_bpf *prog = to_bpf(act);
142         struct tc_act_bpf opt = {
143                 .index   = prog->tcf_index,
144                 .refcnt  = refcount_read(&prog->tcf_refcnt) - ref,
145                 .bindcnt = atomic_read(&prog->tcf_bindcnt) - bind,
146         };
147         struct tcf_t tm;
148         int ret;
149
150         spin_lock_bh(&prog->tcf_lock);
151         opt.action = prog->tcf_action;
152         if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
153                 goto nla_put_failure;
154
155         if (tcf_bpf_is_ebpf(prog))
156                 ret = tcf_bpf_dump_ebpf_info(prog, skb);
157         else
158                 ret = tcf_bpf_dump_bpf_info(prog, skb);
159         if (ret)
160                 goto nla_put_failure;
161
162         tcf_tm_dump(&tm, &prog->tcf_tm);
163         if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm,
164                           TCA_ACT_BPF_PAD))
165                 goto nla_put_failure;
166
167         spin_unlock_bh(&prog->tcf_lock);
168         return skb->len;
169
170 nla_put_failure:
171         spin_unlock_bh(&prog->tcf_lock);
172         nlmsg_trim(skb, tp);
173         return -1;
174 }
175
176 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
177         [TCA_ACT_BPF_PARMS]     = { .len = sizeof(struct tc_act_bpf) },
178         [TCA_ACT_BPF_FD]        = { .type = NLA_U32 },
179         [TCA_ACT_BPF_NAME]      = { .type = NLA_NUL_STRING,
180                                     .len = ACT_BPF_NAME_LEN },
181         [TCA_ACT_BPF_OPS_LEN]   = { .type = NLA_U16 },
182         [TCA_ACT_BPF_OPS]       = { .type = NLA_BINARY,
183                                     .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
184 };
185
186 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
187 {
188         struct sock_filter *bpf_ops;
189         struct sock_fprog_kern fprog_tmp;
190         struct bpf_prog *fp;
191         u16 bpf_size, bpf_num_ops;
192         int ret;
193
194         bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
195         if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0)
196                 return -EINVAL;
197
198         bpf_size = bpf_num_ops * sizeof(*bpf_ops);
199         if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
200                 return -EINVAL;
201
202         bpf_ops = kmemdup(nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size, GFP_KERNEL);
203         if (bpf_ops == NULL)
204                 return -ENOMEM;
205
206         fprog_tmp.len = bpf_num_ops;
207         fprog_tmp.filter = bpf_ops;
208
209         ret = bpf_prog_create(&fp, &fprog_tmp);
210         if (ret < 0) {
211                 kfree(bpf_ops);
212                 return ret;
213         }
214
215         cfg->bpf_ops = bpf_ops;
216         cfg->bpf_num_ops = bpf_num_ops;
217         cfg->filter = fp;
218         cfg->is_ebpf = false;
219
220         return 0;
221 }
222
223 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
224 {
225         struct bpf_prog *fp;
226         char *name = NULL;
227         u32 bpf_fd;
228
229         bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
230
231         fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT);
232         if (IS_ERR(fp))
233                 return PTR_ERR(fp);
234
235         if (tb[TCA_ACT_BPF_NAME]) {
236                 name = nla_memdup(tb[TCA_ACT_BPF_NAME], GFP_KERNEL);
237                 if (!name) {
238                         bpf_prog_put(fp);
239                         return -ENOMEM;
240                 }
241         }
242
243         cfg->bpf_name = name;
244         cfg->filter = fp;
245         cfg->is_ebpf = true;
246
247         return 0;
248 }
249
250 static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg)
251 {
252         struct bpf_prog *filter = cfg->filter;
253
254         if (filter) {
255                 if (cfg->is_ebpf)
256                         bpf_prog_put(filter);
257                 else
258                         bpf_prog_destroy(filter);
259         }
260
261         kfree(cfg->bpf_ops);
262         kfree(cfg->bpf_name);
263 }
264
265 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
266                                   struct tcf_bpf_cfg *cfg)
267 {
268         cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
269         /* updates to prog->filter are prevented, since it's called either
270          * with tcf lock or during final cleanup in rcu callback
271          */
272         cfg->filter = rcu_dereference_protected(prog->filter, 1);
273
274         cfg->bpf_ops = prog->bpf_ops;
275         cfg->bpf_name = prog->bpf_name;
276 }
277
278 static int tcf_bpf_init(struct net *net, struct nlattr *nla,
279                         struct nlattr *est, struct tc_action **act,
280                         int replace, int bind, bool rtnl_held,
281                         struct netlink_ext_ack *extack)
282 {
283         struct tc_action_net *tn = net_generic(net, bpf_net_id);
284         struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
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(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy, NULL);
296         if (ret < 0)
297                 return ret;
298
299         if (!tb[TCA_ACT_BPF_PARMS])
300                 return -EINVAL;
301
302         parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
303         index = parm->index;
304         ret = tcf_idr_check_alloc(tn, &index, act, bind);
305         if (!ret) {
306                 ret = tcf_idr_create(tn, index, est, act,
307                                      &act_bpf_ops, bind, true);
308                 if (ret < 0) {
309                         tcf_idr_cleanup(tn, index);
310                         return ret;
311                 }
312
313                 res = ACT_P_CREATED;
314         } else if (ret > 0) {
315                 /* Don't override defaults. */
316                 if (bind)
317                         return 0;
318
319                 if (!replace) {
320                         tcf_idr_release(*act, bind);
321                         return -EEXIST;
322                 }
323         } else {
324                 return ret;
325         }
326
327         is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
328         is_ebpf = tb[TCA_ACT_BPF_FD];
329
330         if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) {
331                 ret = -EINVAL;
332                 goto out;
333         }
334
335         memset(&cfg, 0, sizeof(cfg));
336
337         ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
338                        tcf_bpf_init_from_efd(tb, &cfg);
339         if (ret < 0)
340                 goto out;
341
342         prog = to_bpf(*act);
343
344         spin_lock_bh(&prog->tcf_lock);
345         if (res != ACT_P_CREATED)
346                 tcf_bpf_prog_fill_cfg(prog, &old);
347
348         prog->bpf_ops = cfg.bpf_ops;
349         prog->bpf_name = cfg.bpf_name;
350
351         if (cfg.bpf_num_ops)
352                 prog->bpf_num_ops = cfg.bpf_num_ops;
353
354         prog->tcf_action = parm->action;
355         rcu_assign_pointer(prog->filter, cfg.filter);
356         spin_unlock_bh(&prog->tcf_lock);
357
358         if (res == ACT_P_CREATED) {
359                 tcf_idr_insert(tn, *act);
360         } else {
361                 /* make sure the program being replaced is no longer executing */
362                 synchronize_rcu();
363                 tcf_bpf_cfg_cleanup(&old);
364         }
365
366         return res;
367 out:
368         tcf_idr_release(*act, bind);
369
370         return ret;
371 }
372
373 static void tcf_bpf_cleanup(struct tc_action *act)
374 {
375         struct tcf_bpf_cfg tmp;
376
377         tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp);
378         tcf_bpf_cfg_cleanup(&tmp);
379 }
380
381 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb,
382                           struct netlink_callback *cb, int type,
383                           const struct tc_action_ops *ops,
384                           struct netlink_ext_ack *extack)
385 {
386         struct tc_action_net *tn = net_generic(net, bpf_net_id);
387
388         return tcf_generic_walker(tn, skb, cb, type, ops, extack);
389 }
390
391 static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index,
392                           struct netlink_ext_ack *extack)
393 {
394         struct tc_action_net *tn = net_generic(net, bpf_net_id);
395
396         return tcf_idr_search(tn, a, index);
397 }
398
399 static struct tc_action_ops act_bpf_ops __read_mostly = {
400         .kind           =       "bpf",
401         .type           =       TCA_ACT_BPF,
402         .owner          =       THIS_MODULE,
403         .act            =       tcf_bpf_act,
404         .dump           =       tcf_bpf_dump,
405         .cleanup        =       tcf_bpf_cleanup,
406         .init           =       tcf_bpf_init,
407         .walk           =       tcf_bpf_walker,
408         .lookup         =       tcf_bpf_search,
409         .size           =       sizeof(struct tcf_bpf),
410 };
411
412 static __net_init int bpf_init_net(struct net *net)
413 {
414         struct tc_action_net *tn = net_generic(net, bpf_net_id);
415
416         return tc_action_net_init(net, tn, &act_bpf_ops);
417 }
418
419 static void __net_exit bpf_exit_net(struct list_head *net_list)
420 {
421         tc_action_net_exit(net_list, bpf_net_id);
422 }
423
424 static struct pernet_operations bpf_net_ops = {
425         .init = bpf_init_net,
426         .exit_batch = bpf_exit_net,
427         .id   = &bpf_net_id,
428         .size = sizeof(struct tc_action_net),
429 };
430
431 static int __init bpf_init_module(void)
432 {
433         return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
434 }
435
436 static void __exit bpf_cleanup_module(void)
437 {
438         tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
439 }
440
441 module_init(bpf_init_module);
442 module_exit(bpf_cleanup_module);
443
444 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
445 MODULE_DESCRIPTION("TC BPF based action");
446 MODULE_LICENSE("GPL v2");