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Linux/net/sched/act_bpf.c

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  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 tcf_bpf(struct sk_buff *skb, const struct tc_action *act,
 37                    struct tcf_result *res)
 38 {
 39         struct tcf_bpf *prog = act->priv;
 40         int action, filter_res;
 41         bool at_ingress = G_TC_AT(skb->tc_verd) & AT_INGRESS;
 42 
 43         if (unlikely(!skb_mac_header_was_set(skb)))
 44                 return TC_ACT_UNSPEC;
 45 
 46         spin_lock(&prog->tcf_lock);
 47 
 48         prog->tcf_tm.lastuse = jiffies;
 49         bstats_update(&prog->tcf_bstats, skb);
 50 
 51         /* Needed here for accessing maps. */
 52         rcu_read_lock();
 53         if (at_ingress) {
 54                 __skb_push(skb, skb->mac_len);
 55                 filter_res = BPF_PROG_RUN(prog->filter, skb);
 56                 __skb_pull(skb, skb->mac_len);
 57         } else {
 58                 filter_res = BPF_PROG_RUN(prog->filter, skb);
 59         }
 60         rcu_read_unlock();
 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 unkown, 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                 action = filter_res;
 77                 break;
 78         case TC_ACT_SHOT:
 79                 action = filter_res;
 80                 prog->tcf_qstats.drops++;
 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         spin_unlock(&prog->tcf_lock);
 91         return action;
 92 }
 93 
 94 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
 95 {
 96         return !prog->bpf_ops;
 97 }
 98 
 99 static 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 
117 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
118                                   struct sk_buff *skb)
119 {
120         if (nla_put_u32(skb, TCA_ACT_BPF_FD, prog->bpf_fd))
121                 return -EMSGSIZE;
122 
123         if (prog->bpf_name &&
124             nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
125                 return -EMSGSIZE;
126 
127         return 0;
128 }
129 
130 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
131                         int bind, int ref)
132 {
133         unsigned char *tp = skb_tail_pointer(skb);
134         struct tcf_bpf *prog = act->priv;
135         struct tc_act_bpf opt = {
136                 .index   = prog->tcf_index,
137                 .refcnt  = prog->tcf_refcnt - ref,
138                 .bindcnt = prog->tcf_bindcnt - bind,
139                 .action  = prog->tcf_action,
140         };
141         struct tcf_t tm;
142         int ret;
143 
144         if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
145                 goto nla_put_failure;
146 
147         if (tcf_bpf_is_ebpf(prog))
148                 ret = tcf_bpf_dump_ebpf_info(prog, skb);
149         else
150                 ret = tcf_bpf_dump_bpf_info(prog, skb);
151         if (ret)
152                 goto nla_put_failure;
153 
154         tm.install = jiffies_to_clock_t(jiffies - prog->tcf_tm.install);
155         tm.lastuse = jiffies_to_clock_t(jiffies - prog->tcf_tm.lastuse);
156         tm.expires = jiffies_to_clock_t(prog->tcf_tm.expires);
157 
158         if (nla_put(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm))
159                 goto nla_put_failure;
160 
161         return skb->len;
162 
163 nla_put_failure:
164         nlmsg_trim(skb, tp);
165         return -1;
166 }
167 
168 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
169         [TCA_ACT_BPF_PARMS]     = { .len = sizeof(struct tc_act_bpf) },
170         [TCA_ACT_BPF_FD]        = { .type = NLA_U32 },
171         [TCA_ACT_BPF_NAME]      = { .type = NLA_NUL_STRING, .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 
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 
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(bpf_fd);
225         if (IS_ERR(fp))
226                 return PTR_ERR(fp);
227 
228         if (fp->type != BPF_PROG_TYPE_SCHED_ACT) {
229                 bpf_prog_put(fp);
230                 return -EINVAL;
231         }
232 
233         if (tb[TCA_ACT_BPF_NAME]) {
234                 name = kmemdup(nla_data(tb[TCA_ACT_BPF_NAME]),
235                                nla_len(tb[TCA_ACT_BPF_NAME]),
236                                GFP_KERNEL);
237                 if (!name) {
238                         bpf_prog_put(fp);
239                         return -ENOMEM;
240                 }
241         }
242 
243         cfg->bpf_fd = bpf_fd;
244         cfg->bpf_name = name;
245         cfg->filter = fp;
246         cfg->is_ebpf = true;
247 
248         return 0;
249 }
250 
251 static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg)
252 {
253         if (cfg->is_ebpf)
254                 bpf_prog_put(cfg->filter);
255         else
256                 bpf_prog_destroy(cfg->filter);
257 
258         kfree(cfg->bpf_ops);
259         kfree(cfg->bpf_name);
260 }
261 
262 static 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         cfg->filter = prog->filter;
267 
268         cfg->bpf_ops = prog->bpf_ops;
269         cfg->bpf_name = prog->bpf_name;
270 }
271 
272 static int tcf_bpf_init(struct net *net, struct nlattr *nla,
273                         struct nlattr *est, struct tc_action *act,
274                         int replace, int bind)
275 {
276         struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
277         struct tcf_bpf_cfg cfg, old;
278         struct tc_act_bpf *parm;
279         struct tcf_bpf *prog;
280         bool is_bpf, is_ebpf;
281         int ret;
282 
283         if (!nla)
284                 return -EINVAL;
285 
286         ret = nla_parse_nested(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy);
287         if (ret < 0)
288                 return ret;
289 
290         is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
291         is_ebpf = tb[TCA_ACT_BPF_FD];
292 
293         if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf) ||
294             !tb[TCA_ACT_BPF_PARMS])
295                 return -EINVAL;
296 
297         parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
298 
299         memset(&cfg, 0, sizeof(cfg));
300 
301         ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
302                        tcf_bpf_init_from_efd(tb, &cfg);
303         if (ret < 0)
304                 return ret;
305 
306         if (!tcf_hash_check(parm->index, act, bind)) {
307                 ret = tcf_hash_create(parm->index, est, act,
308                                       sizeof(*prog), bind);
309                 if (ret < 0)
310                         goto destroy_fp;
311 
312                 ret = ACT_P_CREATED;
313         } else {
314                 /* Don't override defaults. */
315                 if (bind)
316                         goto destroy_fp;
317 
318                 tcf_hash_release(act, bind);
319                 if (!replace) {
320                         ret = -EEXIST;
321                         goto destroy_fp;
322                 }
323         }
324 
325         prog = to_bpf(act);
326         spin_lock_bh(&prog->tcf_lock);
327 
328         if (ret != ACT_P_CREATED)
329                 tcf_bpf_prog_fill_cfg(prog, &old);
330 
331         prog->bpf_ops = cfg.bpf_ops;
332         prog->bpf_name = cfg.bpf_name;
333 
334         if (cfg.bpf_num_ops)
335                 prog->bpf_num_ops = cfg.bpf_num_ops;
336         if (cfg.bpf_fd)
337                 prog->bpf_fd = cfg.bpf_fd;
338 
339         prog->tcf_action = parm->action;
340         prog->filter = cfg.filter;
341 
342         spin_unlock_bh(&prog->tcf_lock);
343 
344         if (ret == ACT_P_CREATED)
345                 tcf_hash_insert(act);
346         else
347                 tcf_bpf_cfg_cleanup(&old);
348 
349         return ret;
350 
351 destroy_fp:
352         tcf_bpf_cfg_cleanup(&cfg);
353         return ret;
354 }
355 
356 static void tcf_bpf_cleanup(struct tc_action *act, int bind)
357 {
358         struct tcf_bpf_cfg tmp;
359 
360         tcf_bpf_prog_fill_cfg(act->priv, &tmp);
361         tcf_bpf_cfg_cleanup(&tmp);
362 }
363 
364 static struct tc_action_ops act_bpf_ops __read_mostly = {
365         .kind           =       "bpf",
366         .type           =       TCA_ACT_BPF,
367         .owner          =       THIS_MODULE,
368         .act            =       tcf_bpf,
369         .dump           =       tcf_bpf_dump,
370         .cleanup        =       tcf_bpf_cleanup,
371         .init           =       tcf_bpf_init,
372 };
373 
374 static int __init bpf_init_module(void)
375 {
376         return tcf_register_action(&act_bpf_ops, BPF_TAB_MASK);
377 }
378 
379 static void __exit bpf_cleanup_module(void)
380 {
381         tcf_unregister_action(&act_bpf_ops);
382 }
383 
384 module_init(bpf_init_module);
385 module_exit(bpf_cleanup_module);
386 
387 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
388 MODULE_DESCRIPTION("TC BPF based action");
389 MODULE_LICENSE("GPL v2");
390 

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