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 #include <net/pkt_cls.h>
  21
  22 #include <linux/tc_act/tc_bpf.h>
  23 #include <net/tc_act/tc_bpf.h>
  24
  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_act(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_pointers(skb);
  54                 filter_res = BPF_PROG_RUN(filter, skb);
  55                 __skb_pull(skb, skb->mac_len);
  56         } else {
  57                 bpf_compute_data_pointers(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  = refcount_read(&prog->tcf_refcnt) - ref,
 146                 .bindcnt = atomic_read(&prog->tcf_bindcnt) - bind,
 147         };
 148         struct tcf_t tm;
 149         int ret;
 150
 151         spin_lock_bh(&prog->tcf_lock);
 152         opt.action = prog->tcf_action;
 153         if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
 154                 goto nla_put_failure;
 155
 156         if (tcf_bpf_is_ebpf(prog))
 157                 ret = tcf_bpf_dump_ebpf_info(prog, skb);
 158         else
 159                 ret = tcf_bpf_dump_bpf_info(prog, skb);
 160         if (ret)
 161                 goto nla_put_failure;
 162
 163         tcf_tm_dump(&tm, &prog->tcf_tm);
 164         if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm,
 165                           TCA_ACT_BPF_PAD))
 166                 goto nla_put_failure;
 167
 168         spin_unlock_bh(&prog->tcf_lock);
 169         return skb->len;
 170
 171 nla_put_failure:
 172         spin_unlock_bh(&prog->tcf_lock);
 173         nlmsg_trim(skb, tp);
 174         return -1;
 175 }
 176
 177 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
 178         [TCA_ACT_BPF_PARMS]     = { .len = sizeof(struct tc_act_bpf) },
 179         [TCA_ACT_BPF_FD]        = { .type = NLA_U32 },
 180         [TCA_ACT_BPF_NAME]      = { .type = NLA_NUL_STRING,
 181                                     .len = ACT_BPF_NAME_LEN },
 182         [TCA_ACT_BPF_OPS_LEN]   = { .type = NLA_U16 },
 183         [TCA_ACT_BPF_OPS]       = { .type = NLA_BINARY,
 184                                     .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
 185 };
 186
 187 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 188 {
 189         struct sock_filter *bpf_ops;
 190         struct sock_fprog_kern fprog_tmp;
 191         struct bpf_prog *fp;
 192         u16 bpf_size, bpf_num_ops;
 193         int ret;
 194
 195         bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
 196         if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0)
 197                 return -EINVAL;
 198
 199         bpf_size = bpf_num_ops * sizeof(*bpf_ops);
 200         if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
 201                 return -EINVAL;
 202
 203         bpf_ops = kmemdup(nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size, GFP_KERNEL);
 204         if (bpf_ops == NULL)
 205                 return -ENOMEM;
 206
 207         fprog_tmp.len = bpf_num_ops;
 208         fprog_tmp.filter = bpf_ops;
 209
 210         ret = bpf_prog_create(&fp, &fprog_tmp);
 211         if (ret < 0) {
 212                 kfree(bpf_ops);
 213                 return ret;
 214         }
 215
 216         cfg->bpf_ops = bpf_ops;
 217         cfg->bpf_num_ops = bpf_num_ops;
 218         cfg->filter = fp;
 219         cfg->is_ebpf = false;
 220
 221         return 0;
 222 }
 223
 224 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 225 {
 226         struct bpf_prog *fp;
 227         char *name = NULL;
 228         u32 bpf_fd;
 229
 230         bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
 231
 232         fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT);
 233         if (IS_ERR(fp))
 234                 return PTR_ERR(fp);
 235
 236         if (tb[TCA_ACT_BPF_NAME]) {
 237                 name = nla_memdup(tb[TCA_ACT_BPF_NAME], GFP_KERNEL);
 238                 if (!name) {
 239                         bpf_prog_put(fp);
 240                         return -ENOMEM;
 241                 }
 242         }
 243
 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         struct bpf_prog *filter = cfg->filter;
 254
 255         if (filter) {
 256                 if (cfg->is_ebpf)
 257                         bpf_prog_put(filter);
 258                 else
 259                         bpf_prog_destroy(filter);
 260         }
 261
 262         kfree(cfg->bpf_ops);
 263         kfree(cfg->bpf_name);
 264 }
 265
 266 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
 267                                   struct tcf_bpf_cfg *cfg)
 268 {
 269         cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
 270         /* updates to prog->filter are prevented, since it's called either
 271          * with tcf lock or during final cleanup in rcu callback
 272          */
 273         cfg->filter = rcu_dereference_protected(prog->filter, 1);
 274
 275         cfg->bpf_ops = prog->bpf_ops;
 276         cfg->bpf_name = prog->bpf_name;
 277 }
 278
 279 static int tcf_bpf_init(struct net *net, struct nlattr *nla,
 280                         struct nlattr *est, struct tc_action **act,
 281                         int replace, int bind, bool rtnl_held,
 282                         struct tcf_proto *tp, struct netlink_ext_ack *extack)
 283 {
 284         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 285         struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
 286         struct tcf_chain *goto_ch = NULL;
 287         struct tcf_bpf_cfg cfg, old;
 288         struct tc_act_bpf *parm;
 289         struct tcf_bpf *prog;
 290         bool is_bpf, is_ebpf;
 291         int ret, res = 0;
 292
 293         if (!nla)
 294                 return -EINVAL;
 295
 296         ret = nla_parse_nested(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy, NULL);
 297         if (ret < 0)
 298                 return ret;
 299
 300         if (!tb[TCA_ACT_BPF_PARMS])
 301                 return -EINVAL;
 302
 303         parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
 304
 305         ret = tcf_idr_check_alloc(tn, &parm->index, act, bind);
 306         if (!ret) {
 307                 ret = tcf_idr_create(tn, parm->index, est, act,
 308                                      &act_bpf_ops, bind, true);
 309                 if (ret < 0) {
 310                         tcf_idr_cleanup(tn, parm->index);
 311                         return ret;
 312                 }
 313
 314                 res = ACT_P_CREATED;
 315         } else if (ret > 0) {
 316                 /* Don't override defaults. */
 317                 if (bind)
 318                         return 0;
 319
 320                 if (!replace) {
 321                         tcf_idr_release(*act, bind);
 322                         return -EEXIST;
 323                 }
 324         } else {
 325                 return ret;
 326         }
 327
 328         ret = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
 329         if (ret < 0)
 330                 goto release_idr;
 331
 332         is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
 333         is_ebpf = tb[TCA_ACT_BPF_FD];
 334
 335         if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) {
 336                 ret = -EINVAL;
 337                 goto put_chain;
 338         }
 339
 340         memset(&cfg, 0, sizeof(cfg));
 341
 342         ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
 343                        tcf_bpf_init_from_efd(tb, &cfg);
 344         if (ret < 0)
 345                 goto put_chain;
 346
 347         prog = to_bpf(*act);
 348
 349         spin_lock_bh(&prog->tcf_lock);
 350         if (res != ACT_P_CREATED)
 351                 tcf_bpf_prog_fill_cfg(prog, &old);
 352
 353         prog->bpf_ops = cfg.bpf_ops;
 354         prog->bpf_name = cfg.bpf_name;
 355
 356         if (cfg.bpf_num_ops)
 357                 prog->bpf_num_ops = cfg.bpf_num_ops;
 358
 359         goto_ch = tcf_action_set_ctrlact(*act, parm->action, goto_ch);
 360         rcu_assign_pointer(prog->filter, cfg.filter);
 361         spin_unlock_bh(&prog->tcf_lock);
 362
 363         if (goto_ch)
 364                 tcf_chain_put_by_act(goto_ch);
 365
 366         if (res == ACT_P_CREATED) {
 367                 tcf_idr_insert(tn, *act);
 368         } else {
 369                 /* make sure the program being replaced is no longer executing */
 370                 synchronize_rcu();
 371                 tcf_bpf_cfg_cleanup(&old);
 372         }
 373
 374         return res;
 375
 376 put_chain:
 377         if (goto_ch)
 378                 tcf_chain_put_by_act(goto_ch);
 379
 380 release_idr:
 381         tcf_idr_release(*act, bind);
 382         return ret;
 383 }
 384
 385 static void tcf_bpf_cleanup(struct tc_action *act)
 386 {
 387         struct tcf_bpf_cfg tmp;
 388
 389         tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp);
 390         tcf_bpf_cfg_cleanup(&tmp);
 391 }
 392
 393 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb,
 394                           struct netlink_callback *cb, int type,
 395                           const struct tc_action_ops *ops,
 396                           struct netlink_ext_ack *extack)
 397 {
 398         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 399
 400         return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 401 }
 402
 403 static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index)
 404 {
 405         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 406
 407         return tcf_idr_search(tn, a, index);
 408 }
 409
 410 static struct tc_action_ops act_bpf_ops __read_mostly = {
 411         .kind           =       "bpf",
 412         .id             =       TCA_ID_BPF,
 413         .owner          =       THIS_MODULE,
 414         .act            =       tcf_bpf_act,
 415         .dump           =       tcf_bpf_dump,
 416         .cleanup        =       tcf_bpf_cleanup,
 417         .init           =       tcf_bpf_init,
 418         .walk           =       tcf_bpf_walker,
 419         .lookup         =       tcf_bpf_search,
 420         .size           =       sizeof(struct tcf_bpf),
 421 };
 422
 423 static __net_init int bpf_init_net(struct net *net)
 424 {
 425         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 426
 427         return tc_action_net_init(tn, &act_bpf_ops);
 428 }
 429
 430 static void __net_exit bpf_exit_net(struct list_head *net_list)
 431 {
 432         tc_action_net_exit(net_list, bpf_net_id);
 433 }
 434
 435 static struct pernet_operations bpf_net_ops = {
 436         .init = bpf_init_net,
 437         .exit_batch = bpf_exit_net,
 438         .id   = &bpf_net_id,
 439         .size = sizeof(struct tc_action_net),
 440 };
 441
 442 static int __init bpf_init_module(void)
 443 {
 444         return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
 445 }
 446
 447 static void __exit bpf_cleanup_module(void)
 448 {
 449         tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
 450 }
 451
 452 module_init(bpf_init_module);
 453 module_exit(bpf_cleanup_module);
 454
 455 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
 456 MODULE_DESCRIPTION("TC BPF based action");
 457 MODULE_LICENSE("GPL v2");