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/sock.h>
  16 #include <net/pkt_sched.h>
  17 #include <net/pkt_cls.h>
  18
  19 #include <linux/tc_act/tc_bpf.h>
  20 #include <net/tc_act/tc_bpf.h>
  21
  22 #define ACT_BPF_NAME_LEN        256
  23
  24 struct tcf_bpf_cfg {
  25         struct bpf_prog *filter;
  26         struct sock_filter *bpf_ops;
  27         const char *bpf_name;
  28         u16 bpf_num_ops;
  29         bool is_ebpf;
  30 };
  31
  32 static unsigned int bpf_net_id;
  33 static struct tc_action_ops act_bpf_ops;
  34
  35 static int tcf_bpf_act(struct sk_buff *skb, const struct tc_action *act,
  36                        struct tcf_result *res)
  37 {
  38         bool at_ingress = skb_at_tc_ingress(skb);
  39         struct tcf_bpf *prog = to_bpf(act);
  40         struct bpf_prog *filter;
  41         int action, filter_res;
  42
  43         tcf_lastuse_update(&prog->tcf_tm);
  44         bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb);
  45
  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         if (skb_sk_is_prefetched(skb) && filter_res != TC_ACT_OK)
  57                 skb_orphan(skb);
  58
  59         /* A BPF program may overwrite the default action opcode.
  60          * Similarly as in cls_bpf, if filter_res == -1 we use the
  61          * default action specified from tc.
  62          *
  63          * In case a different well-known TC_ACT opcode has been
  64          * returned, it will overwrite the default one.
  65          *
  66          * For everything else that is unknown, TC_ACT_UNSPEC is
  67          * returned.
  68          */
  69         switch (filter_res) {
  70         case TC_ACT_PIPE:
  71         case TC_ACT_RECLASSIFY:
  72         case TC_ACT_OK:
  73         case TC_ACT_REDIRECT:
  74                 action = filter_res;
  75                 break;
  76         case TC_ACT_SHOT:
  77                 action = filter_res;
  78                 qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats));
  79                 break;
  80         case TC_ACT_UNSPEC:
  81                 action = prog->tcf_action;
  82                 break;
  83         default:
  84                 action = TC_ACT_UNSPEC;
  85                 break;
  86         }
  87
  88         return action;
  89 }
  90
  91 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
  92 {
  93         return !prog->bpf_ops;
  94 }
  95
  96 static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog,
  97                                  struct sk_buff *skb)
  98 {
  99         struct nlattr *nla;
 100
 101         if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops))
 102                 return -EMSGSIZE;
 103
 104         nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops *
 105                           sizeof(struct sock_filter));
 106         if (nla == NULL)
 107                 return -EMSGSIZE;
 108
 109         memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
 110
 111         return 0;
 112 }
 113
 114 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
 115                                   struct sk_buff *skb)
 116 {
 117         struct nlattr *nla;
 118
 119         if (prog->bpf_name &&
 120             nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
 121                 return -EMSGSIZE;
 122
 123         if (nla_put_u32(skb, TCA_ACT_BPF_ID, prog->filter->aux->id))
 124                 return -EMSGSIZE;
 125
 126         nla = nla_reserve(skb, TCA_ACT_BPF_TAG, sizeof(prog->filter->tag));
 127         if (nla == NULL)
 128                 return -EMSGSIZE;
 129
 130         memcpy(nla_data(nla), prog->filter->tag, nla_len(nla));
 131
 132         return 0;
 133 }
 134
 135 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
 136                         int bind, int ref)
 137 {
 138         unsigned char *tp = skb_tail_pointer(skb);
 139         struct tcf_bpf *prog = to_bpf(act);
 140         struct tc_act_bpf opt = {
 141                 .index   = prog->tcf_index,
 142                 .refcnt  = refcount_read(&prog->tcf_refcnt) - ref,
 143                 .bindcnt = atomic_read(&prog->tcf_bindcnt) - bind,
 144         };
 145         struct tcf_t tm;
 146         int ret;
 147
 148         spin_lock_bh(&prog->tcf_lock);
 149         opt.action = prog->tcf_action;
 150         if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
 151                 goto nla_put_failure;
 152
 153         if (tcf_bpf_is_ebpf(prog))
 154                 ret = tcf_bpf_dump_ebpf_info(prog, skb);
 155         else
 156                 ret = tcf_bpf_dump_bpf_info(prog, skb);
 157         if (ret)
 158                 goto nla_put_failure;
 159
 160         tcf_tm_dump(&tm, &prog->tcf_tm);
 161         if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm,
 162                           TCA_ACT_BPF_PAD))
 163                 goto nla_put_failure;
 164
 165         spin_unlock_bh(&prog->tcf_lock);
 166         return skb->len;
 167
 168 nla_put_failure:
 169         spin_unlock_bh(&prog->tcf_lock);
 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 = kmemdup(nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size, GFP_KERNEL);
 201         if (bpf_ops == NULL)
 202                 return -ENOMEM;
 203
 204         fprog_tmp.len = bpf_num_ops;
 205         fprog_tmp.filter = bpf_ops;
 206
 207         ret = bpf_prog_create(&fp, &fprog_tmp);
 208         if (ret < 0) {
 209                 kfree(bpf_ops);
 210                 return ret;
 211         }
 212
 213         cfg->bpf_ops = bpf_ops;
 214         cfg->bpf_num_ops = bpf_num_ops;
 215         cfg->filter = fp;
 216         cfg->is_ebpf = false;
 217
 218         return 0;
 219 }
 220
 221 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 222 {
 223         struct bpf_prog *fp;
 224         char *name = NULL;
 225         u32 bpf_fd;
 226
 227         bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
 228
 229         fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT);
 230         if (IS_ERR(fp))
 231                 return PTR_ERR(fp);
 232
 233         if (tb[TCA_ACT_BPF_NAME]) {
 234                 name = nla_memdup(tb[TCA_ACT_BPF_NAME], GFP_KERNEL);
 235                 if (!name) {
 236                         bpf_prog_put(fp);
 237                         return -ENOMEM;
 238                 }
 239         }
 240
 241         cfg->bpf_name = name;
 242         cfg->filter = fp;
 243         cfg->is_ebpf = true;
 244
 245         return 0;
 246 }
 247
 248 static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg)
 249 {
 250         struct bpf_prog *filter = cfg->filter;
 251
 252         if (filter) {
 253                 if (cfg->is_ebpf)
 254                         bpf_prog_put(filter);
 255                 else
 256                         bpf_prog_destroy(filter);
 257         }
 258
 259         kfree(cfg->bpf_ops);
 260         kfree(cfg->bpf_name);
 261 }
 262
 263 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
 264                                   struct tcf_bpf_cfg *cfg)
 265 {
 266         cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
 267         /* updates to prog->filter are prevented, since it's called either
 268          * with tcf lock or during final cleanup in rcu callback
 269          */
 270         cfg->filter = rcu_dereference_protected(prog->filter, 1);
 271
 272         cfg->bpf_ops = prog->bpf_ops;
 273         cfg->bpf_name = prog->bpf_name;
 274 }
 275
 276 static int tcf_bpf_init(struct net *net, struct nlattr *nla,
 277                         struct nlattr *est, struct tc_action **act,
 278                         int replace, int bind, bool rtnl_held,
 279                         struct tcf_proto *tp, u32 flags,
 280                         struct netlink_ext_ack *extack)
 281 {
 282         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 283         struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
 284         struct tcf_chain *goto_ch = NULL;
 285         struct tcf_bpf_cfg cfg, old;
 286         struct tc_act_bpf *parm;
 287         struct tcf_bpf *prog;
 288         bool is_bpf, is_ebpf;
 289         int ret, res = 0;
 290         u32 index;
 291
 292         if (!nla)
 293                 return -EINVAL;
 294
 295         ret = nla_parse_nested_deprecated(tb, TCA_ACT_BPF_MAX, nla,
 296                                           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         index = parm->index;
 305         ret = tcf_idr_check_alloc(tn, &index, act, bind);
 306         if (!ret) {
 307                 ret = tcf_idr_create(tn, index, est, act,
 308                                      &act_bpf_ops, bind, true, 0);
 309                 if (ret < 0) {
 310                         tcf_idr_cleanup(tn, 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                 /* make sure the program being replaced is no longer executing */
 368                 synchronize_rcu();
 369                 tcf_bpf_cfg_cleanup(&old);
 370         }
 371
 372         return res;
 373
 374 put_chain:
 375         if (goto_ch)
 376                 tcf_chain_put_by_act(goto_ch);
 377
 378 release_idr:
 379         tcf_idr_release(*act, bind);
 380         return ret;
 381 }
 382
 383 static void tcf_bpf_cleanup(struct tc_action *act)
 384 {
 385         struct tcf_bpf_cfg tmp;
 386
 387         tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp);
 388         tcf_bpf_cfg_cleanup(&tmp);
 389 }
 390
 391 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb,
 392                           struct netlink_callback *cb, int type,
 393                           const struct tc_action_ops *ops,
 394                           struct netlink_ext_ack *extack)
 395 {
 396         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 397
 398         return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 399 }
 400
 401 static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index)
 402 {
 403         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 404
 405         return tcf_idr_search(tn, a, index);
 406 }
 407
 408 static struct tc_action_ops act_bpf_ops __read_mostly = {
 409         .kind           =       "bpf",
 410         .id             =       TCA_ID_BPF,
 411         .owner          =       THIS_MODULE,
 412         .act            =       tcf_bpf_act,
 413         .dump           =       tcf_bpf_dump,
 414         .cleanup        =       tcf_bpf_cleanup,
 415         .init           =       tcf_bpf_init,
 416         .walk           =       tcf_bpf_walker,
 417         .lookup         =       tcf_bpf_search,
 418         .size           =       sizeof(struct tcf_bpf),
 419 };
 420
 421 static __net_init int bpf_init_net(struct net *net)
 422 {
 423         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 424
 425         return tc_action_net_init(net, tn, &act_bpf_ops);
 426 }
 427
 428 static void __net_exit bpf_exit_net(struct list_head *net_list)
 429 {
 430         tc_action_net_exit(net_list, bpf_net_id);
 431 }
 432
 433 static struct pernet_operations bpf_net_ops = {
 434         .init = bpf_init_net,
 435         .exit_batch = bpf_exit_net,
 436         .id   = &bpf_net_id,
 437         .size = sizeof(struct tc_action_net),
 438 };
 439
 440 static int __init bpf_init_module(void)
 441 {
 442         return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
 443 }
 444
 445 static void __exit bpf_cleanup_module(void)
 446 {
 447         tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
 448 }
 449
 450 module_init(bpf_init_module);
 451 module_exit(bpf_cleanup_module);
 452
 453 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
 454 MODULE_DESCRIPTION("TC BPF based action");
 455 MODULE_LICENSE("GPL v2");