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 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         u16 bpf_num_ops;
  32         bool is_ebpf;
  33 };
  34
  35 static unsigned int bpf_net_id;
  36 static struct tc_action_ops act_bpf_ops;
  37
  38 static int tcf_bpf(struct sk_buff *skb, const struct tc_action *act,
  39                    struct tcf_result *res)
  40 {
  41         bool at_ingress = skb_at_tc_ingress(skb);
  42         struct tcf_bpf *prog = to_bpf(act);
  43         struct bpf_prog *filter;
  44         int action, filter_res;
  45
  46         tcf_lastuse_update(&prog->tcf_tm);
  47         bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb);
  48
  49         rcu_read_lock();
  50         filter = rcu_dereference(prog->filter);
  51         if (at_ingress) {
  52                 __skb_push(skb, skb->mac_len);
  53                 bpf_compute_data_end(skb);
  54                 filter_res = BPF_PROG_RUN(filter, skb);
  55                 __skb_pull(skb, skb->mac_len);
  56         } else {
  57                 bpf_compute_data_end(skb);
  58                 filter_res = BPF_PROG_RUN(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         case TC_ACT_REDIRECT:
  77                 action = filter_res;
  78                 break;
  79         case TC_ACT_SHOT:
  80                 action = filter_res;
  81                 qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats));
  82                 break;
  83         case TC_ACT_UNSPEC:
  84                 action = prog->tcf_action;
  85                 break;
  86         default:
  87                 action = TC_ACT_UNSPEC;
  88                 break;
  89         }
  90
  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         struct nlattr *nla;
 121
 122         if (prog->bpf_name &&
 123             nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
 124                 return -EMSGSIZE;
 125
 126         if (nla_put_u32(skb, TCA_ACT_BPF_ID, prog->filter->aux->id))
 127                 return -EMSGSIZE;
 128
 129         nla = nla_reserve(skb, TCA_ACT_BPF_TAG, sizeof(prog->filter->tag));
 130         if (nla == NULL)
 131                 return -EMSGSIZE;
 132
 133         memcpy(nla_data(nla), prog->filter->tag, nla_len(nla));
 134
 135         return 0;
 136 }
 137
 138 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
 139                         int bind, int ref)
 140 {
 141         unsigned char *tp = skb_tail_pointer(skb);
 142         struct tcf_bpf *prog = to_bpf(act);
 143         struct tc_act_bpf opt = {
 144                 .index   = prog->tcf_index,
 145                 .refcnt  = prog->tcf_refcnt - ref,
 146                 .bindcnt = prog->tcf_bindcnt - bind,
 147                 .action  = prog->tcf_action,
 148         };
 149         struct tcf_t tm;
 150         int ret;
 151
 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         return skb->len;
 168
 169 nla_put_failure:
 170         nlmsg_trim(skb, tp);
 171         return -1;
 172 }
 173
 174 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
 175         [TCA_ACT_BPF_PARMS]     = { .len = sizeof(struct tc_act_bpf) },
 176         [TCA_ACT_BPF_FD]        = { .type = NLA_U32 },
 177         [TCA_ACT_BPF_NAME]      = { .type = NLA_NUL_STRING,
 178                                     .len = ACT_BPF_NAME_LEN },
 179         [TCA_ACT_BPF_OPS_LEN]   = { .type = NLA_U16 },
 180         [TCA_ACT_BPF_OPS]       = { .type = NLA_BINARY,
 181                                     .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
 182 };
 183
 184 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 185 {
 186         struct sock_filter *bpf_ops;
 187         struct sock_fprog_kern fprog_tmp;
 188         struct bpf_prog *fp;
 189         u16 bpf_size, bpf_num_ops;
 190         int ret;
 191
 192         bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
 193         if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0)
 194                 return -EINVAL;
 195
 196         bpf_size = bpf_num_ops * sizeof(*bpf_ops);
 197         if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
 198                 return -EINVAL;
 199
 200         bpf_ops = kzalloc(bpf_size, GFP_KERNEL);
 201         if (bpf_ops == NULL)
 202                 return -ENOMEM;
 203
 204         memcpy(bpf_ops, nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size);
 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         if (cfg->is_ebpf)
 253                 bpf_prog_put(cfg->filter);
 254         else
 255                 bpf_prog_destroy(cfg->filter);
 256
 257         kfree(cfg->bpf_ops);
 258         kfree(cfg->bpf_name);
 259 }
 260
 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
 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, NULL);
 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
 342         prog->tcf_action = parm->action;
 343         rcu_assign_pointer(prog->filter, cfg.filter);
 344
 345         if (res == ACT_P_CREATED) {
 346                 tcf_hash_insert(tn, *act);
 347         } else {
 348                 /* make sure the program being replaced is no longer executing */
 349                 synchronize_rcu();
 350                 tcf_bpf_cfg_cleanup(&old);
 351         }
 352
 353         return res;
 354 out:
 355         if (res == ACT_P_CREATED)
 356                 tcf_hash_cleanup(*act, est);
 357
 358         return ret;
 359 }
 360
 361 static void tcf_bpf_cleanup(struct tc_action *act, int bind)
 362 {
 363         struct tcf_bpf_cfg tmp;
 364
 365         tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp);
 366         tcf_bpf_cfg_cleanup(&tmp);
 367 }
 368
 369 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb,
 370                           struct netlink_callback *cb, int type,
 371                           const struct tc_action_ops *ops)
 372 {
 373         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 374
 375         return tcf_generic_walker(tn, skb, cb, type, ops);
 376 }
 377
 378 static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index)
 379 {
 380         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 381
 382         return tcf_hash_search(tn, a, index);
 383 }
 384
 385 static struct tc_action_ops act_bpf_ops __read_mostly = {
 386         .kind           =       "bpf",
 387         .type           =       TCA_ACT_BPF,
 388         .owner          =       THIS_MODULE,
 389         .act            =       tcf_bpf,
 390         .dump           =       tcf_bpf_dump,
 391         .cleanup        =       tcf_bpf_cleanup,
 392         .init           =       tcf_bpf_init,
 393         .walk           =       tcf_bpf_walker,
 394         .lookup         =       tcf_bpf_search,
 395         .size           =       sizeof(struct tcf_bpf),
 396 };
 397
 398 static __net_init int bpf_init_net(struct net *net)
 399 {
 400         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 401
 402         return tc_action_net_init(tn, &act_bpf_ops, BPF_TAB_MASK);
 403 }
 404
 405 static void __net_exit bpf_exit_net(struct net *net)
 406 {
 407         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 408
 409         tc_action_net_exit(tn);
 410 }
 411
 412 static struct pernet_operations bpf_net_ops = {
 413         .init = bpf_init_net,
 414         .exit = bpf_exit_net,
 415         .id   = &bpf_net_id,
 416         .size = sizeof(struct tc_action_net),
 417 };
 418
 419 static int __init bpf_init_module(void)
 420 {
 421         return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
 422 }
 423
 424 static void __exit bpf_cleanup_module(void)
 425 {
 426         tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
 427 }
 428
 429 module_init(bpf_init_module);
 430 module_exit(bpf_cleanup_module);
 431
 432 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
 433 MODULE_DESCRIPTION("TC BPF based action");
 434 MODULE_LICENSE("GPL v2");