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(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_end(skb);
  53                 filter_res = BPF_PROG_RUN(filter, skb);
  54                 __skb_pull(skb, skb->mac_len);
  55         } else {
  56                 bpf_compute_data_end(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  = prog->tcf_refcnt - ref,
 145                 .bindcnt = prog->tcf_bindcnt - bind,
 146                 .action  = prog->tcf_action,
 147         };
 148         struct tcf_t tm;
 149         int ret;
 150
 151         if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
 152                 goto nla_put_failure;
 153
 154         if (tcf_bpf_is_ebpf(prog))
 155                 ret = tcf_bpf_dump_ebpf_info(prog, skb);
 156         else
 157                 ret = tcf_bpf_dump_bpf_info(prog, skb);
 158         if (ret)
 159                 goto nla_put_failure;
 160
 161         tcf_tm_dump(&tm, &prog->tcf_tm);
 162         if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm,
 163                           TCA_ACT_BPF_PAD))
 164                 goto nla_put_failure;
 165
 166         return skb->len;
 167
 168 nla_put_failure:
 169         nlmsg_trim(skb, tp);
 170         return -1;
 171 }
 172
 173 static 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
 183 static 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 = kzalloc(bpf_size, GFP_KERNEL);
 200         if (bpf_ops == NULL)
 201                 return -ENOMEM;
 202
 203         memcpy(bpf_ops, nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size);
 204
 205         fprog_tmp.len = bpf_num_ops;
 206         fprog_tmp.filter = bpf_ops;
 207
 208         ret = bpf_prog_create(&fp, &fprog_tmp);
 209         if (ret < 0) {
 210                 kfree(bpf_ops);
 211                 return ret;
 212         }
 213
 214         cfg->bpf_ops = bpf_ops;
 215         cfg->bpf_num_ops = bpf_num_ops;
 216         cfg->filter = fp;
 217         cfg->is_ebpf = false;
 218
 219         return 0;
 220 }
 221
 222 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 223 {
 224         struct bpf_prog *fp;
 225         char *name = NULL;
 226         u32 bpf_fd;
 227
 228         bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
 229
 230         fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT);
 231         if (IS_ERR(fp))
 232                 return PTR_ERR(fp);
 233
 234         if (tb[TCA_ACT_BPF_NAME]) {
 235                 name = nla_memdup(tb[TCA_ACT_BPF_NAME], GFP_KERNEL);
 236                 if (!name) {
 237                         bpf_prog_put(fp);
 238                         return -ENOMEM;
 239                 }
 240         }
 241
 242         cfg->bpf_name = name;
 243         cfg->filter = fp;
 244         cfg->is_ebpf = true;
 245
 246         return 0;
 247 }
 248
 249 static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg)
 250 {
 251         if (cfg->is_ebpf)
 252                 bpf_prog_put(cfg->filter);
 253         else
 254                 bpf_prog_destroy(cfg->filter);
 255
 256         kfree(cfg->bpf_ops);
 257         kfree(cfg->bpf_name);
 258 }
 259
 260 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
 261                                   struct tcf_bpf_cfg *cfg)
 262 {
 263         cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
 264         /* updates to prog->filter are prevented, since it's called either
 265          * with rtnl lock or during final cleanup in rcu callback
 266          */
 267         cfg->filter = rcu_dereference_protected(prog->filter, 1);
 268
 269         cfg->bpf_ops = prog->bpf_ops;
 270         cfg->bpf_name = prog->bpf_name;
 271 }
 272
 273 static int tcf_bpf_init(struct net *net, struct nlattr *nla,
 274                         struct nlattr *est, struct tc_action **act,
 275                         int replace, int bind)
 276 {
 277         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 278         struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
 279         struct tcf_bpf_cfg cfg, old;
 280         struct tc_act_bpf *parm;
 281         struct tcf_bpf *prog;
 282         bool is_bpf, is_ebpf;
 283         int ret, res = 0;
 284
 285         if (!nla)
 286                 return -EINVAL;
 287
 288         ret = nla_parse_nested(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy, NULL);
 289         if (ret < 0)
 290                 return ret;
 291
 292         if (!tb[TCA_ACT_BPF_PARMS])
 293                 return -EINVAL;
 294
 295         parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
 296
 297         if (!tcf_idr_check(tn, parm->index, act, bind)) {
 298                 ret = tcf_idr_create(tn, parm->index, est, act,
 299                                      &act_bpf_ops, bind, true);
 300                 if (ret < 0)
 301                         return ret;
 302
 303                 res = ACT_P_CREATED;
 304         } else {
 305                 /* Don't override defaults. */
 306                 if (bind)
 307                         return 0;
 308
 309                 tcf_idr_release(*act, bind);
 310                 if (!replace)
 311                         return -EEXIST;
 312         }
 313
 314         is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
 315         is_ebpf = tb[TCA_ACT_BPF_FD];
 316
 317         if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) {
 318                 ret = -EINVAL;
 319                 goto out;
 320         }
 321
 322         memset(&cfg, 0, sizeof(cfg));
 323
 324         ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
 325                        tcf_bpf_init_from_efd(tb, &cfg);
 326         if (ret < 0)
 327                 goto out;
 328
 329         prog = to_bpf(*act);
 330         ASSERT_RTNL();
 331
 332         if (res != ACT_P_CREATED)
 333                 tcf_bpf_prog_fill_cfg(prog, &old);
 334
 335         prog->bpf_ops = cfg.bpf_ops;
 336         prog->bpf_name = cfg.bpf_name;
 337
 338         if (cfg.bpf_num_ops)
 339                 prog->bpf_num_ops = cfg.bpf_num_ops;
 340
 341         prog->tcf_action = parm->action;
 342         rcu_assign_pointer(prog->filter, cfg.filter);
 343
 344         if (res == ACT_P_CREATED) {
 345                 tcf_idr_insert(tn, *act);
 346         } else {
 347                 /* make sure the program being replaced is no longer executing */
 348                 synchronize_rcu();
 349                 tcf_bpf_cfg_cleanup(&old);
 350         }
 351
 352         return res;
 353 out:
 354         if (res == ACT_P_CREATED)
 355                 tcf_idr_cleanup(*act, est);
 356
 357         return ret;
 358 }
 359
 360 static void tcf_bpf_cleanup(struct tc_action *act, int bind)
 361 {
 362         struct tcf_bpf_cfg tmp;
 363
 364         tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp);
 365         tcf_bpf_cfg_cleanup(&tmp);
 366 }
 367
 368 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb,
 369                           struct netlink_callback *cb, int type,
 370                           const struct tc_action_ops *ops)
 371 {
 372         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 373
 374         return tcf_generic_walker(tn, skb, cb, type, ops);
 375 }
 376
 377 static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index)
 378 {
 379         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 380
 381         return tcf_idr_search(tn, a, index);
 382 }
 383
 384 static struct tc_action_ops act_bpf_ops __read_mostly = {
 385         .kind           =       "bpf",
 386         .type           =       TCA_ACT_BPF,
 387         .owner          =       THIS_MODULE,
 388         .act            =       tcf_bpf,
 389         .dump           =       tcf_bpf_dump,
 390         .cleanup        =       tcf_bpf_cleanup,
 391         .init           =       tcf_bpf_init,
 392         .walk           =       tcf_bpf_walker,
 393         .lookup         =       tcf_bpf_search,
 394         .size           =       sizeof(struct tcf_bpf),
 395 };
 396
 397 static __net_init int bpf_init_net(struct net *net)
 398 {
 399         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 400
 401         return tc_action_net_init(tn, &act_bpf_ops);
 402 }
 403
 404 static void __net_exit bpf_exit_net(struct net *net)
 405 {
 406         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 407
 408         tc_action_net_exit(tn);
 409 }
 410
 411 static struct pernet_operations bpf_net_ops = {
 412         .init = bpf_init_net,
 413         .exit = bpf_exit_net,
 414         .id   = &bpf_net_id,
 415         .size = sizeof(struct tc_action_net),
 416 };
 417
 418 static int __init bpf_init_module(void)
 419 {
 420         return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
 421 }
 422
 423 static void __exit bpf_cleanup_module(void)
 424 {
 425         tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
 426 }
 427
 428 module_init(bpf_init_module);
 429 module_exit(bpf_cleanup_module);
 430
 431 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
 432 MODULE_DESCRIPTION("TC BPF based action");
 433 MODULE_LICENSE("GPL v2");