net/sched/act_bpf.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (c) 2015 Jiri Pirko <jiri@resnulli.us>
   4  */
   5
   6 #include <linux/module.h>
   7 #include <linux/init.h>
   8 #include <linux/kernel.h>
   9 #include <linux/skbuff.h>
  10 #include <linux/rtnetlink.h>
  11 #include <linux/filter.h>
  12 #include <linux/bpf.h>
  13
  14 #include <net/netlink.h>
  15 #include <net/pkt_sched.h>
  16 #include <net/pkt_cls.h>
  17
  18 #include <linux/tc_act/tc_bpf.h>
  19 #include <net/tc_act/tc_bpf.h>
  20
  21 #define ACT_BPF_NAME_LEN        256
  22
  23 struct tcf_bpf_cfg {
  24         struct bpf_prog *filter;
  25         struct sock_filter *bpf_ops;
  26         const char *bpf_name;
  27         u16 bpf_num_ops;
  28         bool is_ebpf;
  29 };
  30
  31 static unsigned int bpf_net_id;
  32 static struct tc_action_ops act_bpf_ops;
  33
  34 static int tcf_bpf_act(struct sk_buff *skb, const struct tc_action *act,
  35                        struct tcf_result *res)
  36 {
  37         bool at_ingress = skb_at_tc_ingress(skb);
  38         struct tcf_bpf *prog = to_bpf(act);
  39         struct bpf_prog *filter;
  40         int action, filter_res;
  41
  42         tcf_lastuse_update(&prog->tcf_tm);
  43         bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb);
  44
  45         rcu_read_lock();
  46         filter = rcu_dereference(prog->filter);
  47         if (at_ingress) {
  48                 __skb_push(skb, skb->mac_len);
  49                 bpf_compute_data_pointers(skb);
  50                 filter_res = BPF_PROG_RUN(filter, skb);
  51                 __skb_pull(skb, skb->mac_len);
  52         } else {
  53                 bpf_compute_data_pointers(skb);
  54                 filter_res = BPF_PROG_RUN(filter, skb);
  55         }
  56         rcu_read_unlock();
  57
  58         /* A BPF program may overwrite the default action opcode.
  59          * Similarly as in cls_bpf, if filter_res == -1 we use the
  60          * default action specified from tc.
  61          *
  62          * In case a different well-known TC_ACT opcode has been
  63          * returned, it will overwrite the default one.
  64          *
  65          * For everything else that is unkown, TC_ACT_UNSPEC is
  66          * returned.
  67          */
  68         switch (filter_res) {
  69         case TC_ACT_PIPE:
  70         case TC_ACT_RECLASSIFY:
  71         case TC_ACT_OK:
  72         case TC_ACT_REDIRECT:
  73                 action = filter_res;
  74                 break;
  75         case TC_ACT_SHOT:
  76                 action = filter_res;
  77                 qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats));
  78                 break;
  79         case TC_ACT_UNSPEC:
  80                 action = prog->tcf_action;
  81                 break;
  82         default:
  83                 action = TC_ACT_UNSPEC;
  84                 break;
  85         }
  86
  87         return action;
  88 }
  89
  90 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
  91 {
  92         return !prog->bpf_ops;
  93 }
  94
  95 static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog,
  96                                  struct sk_buff *skb)
  97 {
  98         struct nlattr *nla;
  99
 100         if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops))
 101                 return -EMSGSIZE;
 102
 103         nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops *
 104                           sizeof(struct sock_filter));
 105         if (nla == NULL)
 106                 return -EMSGSIZE;
 107
 108         memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
 109
 110         return 0;
 111 }
 112
 113 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
 114                                   struct sk_buff *skb)
 115 {
 116         struct nlattr *nla;
 117
 118         if (prog->bpf_name &&
 119             nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
 120                 return -EMSGSIZE;
 121
 122         if (nla_put_u32(skb, TCA_ACT_BPF_ID, prog->filter->aux->id))
 123                 return -EMSGSIZE;
 124
 125         nla = nla_reserve(skb, TCA_ACT_BPF_TAG, sizeof(prog->filter->tag));
 126         if (nla == NULL)
 127                 return -EMSGSIZE;
 128
 129         memcpy(nla_data(nla), prog->filter->tag, nla_len(nla));
 130
 131         return 0;
 132 }
 133
 134 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
 135                         int bind, int ref)
 136 {
 137         unsigned char *tp = skb_tail_pointer(skb);
 138         struct tcf_bpf *prog = to_bpf(act);
 139         struct tc_act_bpf opt = {
 140                 .index   = prog->tcf_index,
 141                 .refcnt  = refcount_read(&prog->tcf_refcnt) - ref,
 142                 .bindcnt = atomic_read(&prog->tcf_bindcnt) - bind,
 143         };
 144         struct tcf_t tm;
 145         int ret;
 146
 147         spin_lock_bh(&prog->tcf_lock);
 148         opt.action = prog->tcf_action;
 149         if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
 150                 goto nla_put_failure;
 151
 152         if (tcf_bpf_is_ebpf(prog))
 153                 ret = tcf_bpf_dump_ebpf_info(prog, skb);
 154         else
 155                 ret = tcf_bpf_dump_bpf_info(prog, skb);
 156         if (ret)
 157                 goto nla_put_failure;
 158
 159         tcf_tm_dump(&tm, &prog->tcf_tm);
 160         if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm,
 161                           TCA_ACT_BPF_PAD))
 162                 goto nla_put_failure;
 163
 164         spin_unlock_bh(&prog->tcf_lock);
 165         return skb->len;
 166
 167 nla_put_failure:
 168         spin_unlock_bh(&prog->tcf_lock);
 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 = kmemdup(nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size, GFP_KERNEL);
 200         if (bpf_ops == NULL)
 201                 return -ENOMEM;
 202
 203         fprog_tmp.len = bpf_num_ops;
 204         fprog_tmp.filter = bpf_ops;
 205
 206         ret = bpf_prog_create(&fp, &fprog_tmp);
 207         if (ret < 0) {
 208                 kfree(bpf_ops);
 209                 return ret;
 210         }
 211
 212         cfg->bpf_ops = bpf_ops;
 213         cfg->bpf_num_ops = bpf_num_ops;
 214         cfg->filter = fp;
 215         cfg->is_ebpf = false;
 216
 217         return 0;
 218 }
 219
 220 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 221 {
 222         struct bpf_prog *fp;
 223         char *name = NULL;
 224         u32 bpf_fd;
 225
 226         bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
 227
 228         fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT);
 229         if (IS_ERR(fp))
 230                 return PTR_ERR(fp);
 231
 232         if (tb[TCA_ACT_BPF_NAME]) {
 233                 name = nla_memdup(tb[TCA_ACT_BPF_NAME], GFP_KERNEL);
 234                 if (!name) {
 235                         bpf_prog_put(fp);
 236                         return -ENOMEM;
 237                 }
 238         }
 239
 240         cfg->bpf_name = name;
 241         cfg->filter = fp;
 242         cfg->is_ebpf = true;
 243
 244         return 0;
 245 }
 246
 247 static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg)
 248 {
 249         struct bpf_prog *filter = cfg->filter;
 250
 251         if (filter) {
 252                 if (cfg->is_ebpf)
 253                         bpf_prog_put(filter);
 254                 else
 255                         bpf_prog_destroy(filter);
 256         }
 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         /* updates to prog->filter are prevented, since it's called either
 267          * with tcf lock or during final cleanup in rcu callback
 268          */
 269         cfg->filter = rcu_dereference_protected(prog->filter, 1);
 270
 271         cfg->bpf_ops = prog->bpf_ops;
 272         cfg->bpf_name = prog->bpf_name;
 273 }
 274
 275 static int tcf_bpf_init(struct net *net, struct nlattr *nla,
 276                         struct nlattr *est, struct tc_action **act,
 277                         int replace, int bind, bool rtnl_held,
 278                         struct tcf_proto *tp, struct netlink_ext_ack *extack)
 279 {
 280         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 281         struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
 282         struct tcf_chain *goto_ch = NULL;
 283         struct tcf_bpf_cfg cfg, old;
 284         struct tc_act_bpf *parm;
 285         struct tcf_bpf *prog;
 286         bool is_bpf, is_ebpf;
 287         int ret, res = 0;
 288
 289         if (!nla)
 290                 return -EINVAL;
 291
 292         ret = nla_parse_nested_deprecated(tb, TCA_ACT_BPF_MAX, nla,
 293                                           act_bpf_policy, NULL);
 294         if (ret < 0)
 295                 return ret;
 296
 297         if (!tb[TCA_ACT_BPF_PARMS])
 298                 return -EINVAL;
 299
 300         parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
 301
 302         ret = tcf_idr_check_alloc(tn, &parm->index, act, bind);
 303         if (!ret) {
 304                 ret = tcf_idr_create(tn, parm->index, est, act,
 305                                      &act_bpf_ops, bind, true);
 306                 if (ret < 0) {
 307                         tcf_idr_cleanup(tn, parm->index);
 308                         return ret;
 309                 }
 310
 311                 res = ACT_P_CREATED;
 312         } else if (ret > 0) {
 313                 /* Don't override defaults. */
 314                 if (bind)
 315                         return 0;
 316
 317                 if (!replace) {
 318                         tcf_idr_release(*act, bind);
 319                         return -EEXIST;
 320                 }
 321         } else {
 322                 return ret;
 323         }
 324
 325         ret = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
 326         if (ret < 0)
 327                 goto release_idr;
 328
 329         is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
 330         is_ebpf = tb[TCA_ACT_BPF_FD];
 331
 332         if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) {
 333                 ret = -EINVAL;
 334                 goto put_chain;
 335         }
 336
 337         memset(&cfg, 0, sizeof(cfg));
 338
 339         ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
 340                        tcf_bpf_init_from_efd(tb, &cfg);
 341         if (ret < 0)
 342                 goto put_chain;
 343
 344         prog = to_bpf(*act);
 345
 346         spin_lock_bh(&prog->tcf_lock);
 347         if (res != ACT_P_CREATED)
 348                 tcf_bpf_prog_fill_cfg(prog, &old);
 349
 350         prog->bpf_ops = cfg.bpf_ops;
 351         prog->bpf_name = cfg.bpf_name;
 352
 353         if (cfg.bpf_num_ops)
 354                 prog->bpf_num_ops = cfg.bpf_num_ops;
 355
 356         goto_ch = tcf_action_set_ctrlact(*act, parm->action, goto_ch);
 357         rcu_assign_pointer(prog->filter, cfg.filter);
 358         spin_unlock_bh(&prog->tcf_lock);
 359
 360         if (goto_ch)
 361                 tcf_chain_put_by_act(goto_ch);
 362
 363         if (res == ACT_P_CREATED) {
 364                 tcf_idr_insert(tn, *act);
 365         } else {
 366                 /* make sure the program being replaced is no longer executing */
 367                 synchronize_rcu();
 368                 tcf_bpf_cfg_cleanup(&old);
 369         }
 370
 371         return res;
 372
 373 put_chain:
 374         if (goto_ch)
 375                 tcf_chain_put_by_act(goto_ch);
 376
 377 release_idr:
 378         tcf_idr_release(*act, bind);
 379         return ret;
 380 }
 381
 382 static void tcf_bpf_cleanup(struct tc_action *act)
 383 {
 384         struct tcf_bpf_cfg tmp;
 385
 386         tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp);
 387         tcf_bpf_cfg_cleanup(&tmp);
 388 }
 389
 390 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb,
 391                           struct netlink_callback *cb, int type,
 392                           const struct tc_action_ops *ops,
 393                           struct netlink_ext_ack *extack)
 394 {
 395         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 396
 397         return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 398 }
 399
 400 static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index)
 401 {
 402         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 403
 404         return tcf_idr_search(tn, a, index);
 405 }
 406
 407 static struct tc_action_ops act_bpf_ops __read_mostly = {
 408         .kind           =       "bpf",
 409         .id             =       TCA_ID_BPF,
 410         .owner          =       THIS_MODULE,
 411         .act            =       tcf_bpf_act,
 412         .dump           =       tcf_bpf_dump,
 413         .cleanup        =       tcf_bpf_cleanup,
 414         .init           =       tcf_bpf_init,
 415         .walk           =       tcf_bpf_walker,
 416         .lookup         =       tcf_bpf_search,
 417         .size           =       sizeof(struct tcf_bpf),
 418 };
 419
 420 static __net_init int bpf_init_net(struct net *net)
 421 {
 422         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 423
 424         return tc_action_net_init(tn, &act_bpf_ops);
 425 }
 426
 427 static void __net_exit bpf_exit_net(struct list_head *net_list)
 428 {
 429         tc_action_net_exit(net_list, bpf_net_id);
 430 }
 431
 432 static struct pernet_operations bpf_net_ops = {
 433         .init = bpf_init_net,
 434         .exit_batch = bpf_exit_net,
 435         .id   = &bpf_net_id,
 436         .size = sizeof(struct tc_action_net),
 437 };
 438
 439 static int __init bpf_init_module(void)
 440 {
 441         return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
 442 }
 443
 444 static void __exit bpf_cleanup_module(void)
 445 {
 446         tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
 447 }
 448
 449 module_init(bpf_init_module);
 450 module_exit(bpf_cleanup_module);
 451
 452 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
 453 MODULE_DESCRIPTION("TC BPF based action");
 454 MODULE_LICENSE("GPL v2");