net/sched/act_bpf.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (c) 2015 Jiri Pirko <[email protected]>
   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 #include <net/tc_wrapper.h>
  22
  23 #define ACT_BPF_NAME_LEN        256
  24
  25 struct tcf_bpf_cfg {
  26         struct bpf_prog *filter;
  27         struct sock_filter *bpf_ops;
  28         const char *bpf_name;
  29         u16 bpf_num_ops;
  30         bool is_ebpf;
  31 };
  32
  33 static struct tc_action_ops act_bpf_ops;
  34
  35 TC_INDIRECT_SCOPE int tcf_bpf_act(struct sk_buff *skb,
  36                                   const struct tc_action *act,
  37                                   struct tcf_result *res)
  38 {
  39         bool at_ingress = skb_at_tc_ingress(skb);
  40         struct tcf_bpf *prog = to_bpf(act);
  41         struct bpf_prog *filter;
  42         int action, filter_res;
  43
  44         tcf_lastuse_update(&prog->tcf_tm);
  45         bstats_update(this_cpu_ptr(prog->common.cpu_bstats), skb);
  46
  47         filter = rcu_dereference(prog->filter);
  48         if (at_ingress) {
  49                 __skb_push(skb, skb->mac_len);
  50                 bpf_compute_data_pointers(skb);
  51                 filter_res = bpf_prog_run(filter, skb);
  52                 __skb_pull(skb, skb->mac_len);
  53         } else {
  54                 bpf_compute_data_pointers(skb);
  55                 filter_res = bpf_prog_run(filter, skb);
  56         }
  57         if (unlikely(!skb->tstamp && skb->mono_delivery_time))
  58                 skb->mono_delivery_time = 0;
  59         if (skb_sk_is_prefetched(skb) && filter_res != TC_ACT_OK)
  60                 skb_orphan(skb);
  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 unknown, 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                         struct tcf_proto *tp, u32 flags,
 282                         struct netlink_ext_ack *extack)
 283 {
 284         struct tc_action_net *tn = net_generic(net, act_bpf_ops.net_id);
 285         bool bind = flags & TCA_ACT_FLAGS_BIND;
 286         struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
 287         struct tcf_chain *goto_ch = NULL;
 288         struct tcf_bpf_cfg cfg, old;
 289         struct tc_act_bpf *parm;
 290         struct tcf_bpf *prog;
 291         bool is_bpf, is_ebpf;
 292         int ret, res = 0;
 293         u32 index;
 294
 295         if (!nla)
 296                 return -EINVAL;
 297
 298         ret = nla_parse_nested_deprecated(tb, TCA_ACT_BPF_MAX, nla,
 299                                           act_bpf_policy, NULL);
 300         if (ret < 0)
 301                 return ret;
 302
 303         if (!tb[TCA_ACT_BPF_PARMS])
 304                 return -EINVAL;
 305
 306         parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
 307         index = parm->index;
 308         ret = tcf_idr_check_alloc(tn, &index, act, bind);
 309         if (!ret) {
 310                 ret = tcf_idr_create(tn, index, est, act,
 311                                      &act_bpf_ops, bind, true, flags);
 312                 if (ret < 0) {
 313                         tcf_idr_cleanup(tn, index);
 314                         return ret;
 315                 }
 316
 317                 res = ACT_P_CREATED;
 318         } else if (ret > 0) {
 319                 /* Don't override defaults. */
 320                 if (bind)
 321                         return 0;
 322
 323                 if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
 324                         tcf_idr_release(*act, bind);
 325                         return -EEXIST;
 326                 }
 327         } else {
 328                 return ret;
 329         }
 330
 331         ret = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
 332         if (ret < 0)
 333                 goto release_idr;
 334
 335         is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
 336         is_ebpf = tb[TCA_ACT_BPF_FD];
 337
 338         if (is_bpf == is_ebpf) {
 339                 ret = -EINVAL;
 340                 goto put_chain;
 341         }
 342
 343         memset(&cfg, 0, sizeof(cfg));
 344
 345         ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
 346                        tcf_bpf_init_from_efd(tb, &cfg);
 347         if (ret < 0)
 348                 goto put_chain;
 349
 350         prog = to_bpf(*act);
 351
 352         spin_lock_bh(&prog->tcf_lock);
 353         if (res != ACT_P_CREATED)
 354                 tcf_bpf_prog_fill_cfg(prog, &old);
 355
 356         prog->bpf_ops = cfg.bpf_ops;
 357         prog->bpf_name = cfg.bpf_name;
 358
 359         if (cfg.bpf_num_ops)
 360                 prog->bpf_num_ops = cfg.bpf_num_ops;
 361
 362         goto_ch = tcf_action_set_ctrlact(*act, parm->action, goto_ch);
 363         rcu_assign_pointer(prog->filter, cfg.filter);
 364         spin_unlock_bh(&prog->tcf_lock);
 365
 366         if (goto_ch)
 367                 tcf_chain_put_by_act(goto_ch);
 368
 369         if (res != ACT_P_CREATED) {
 370                 /* make sure the program being replaced is no longer executing */
 371                 synchronize_rcu();
 372                 tcf_bpf_cfg_cleanup(&old);
 373         }
 374
 375         return res;
 376
 377 put_chain:
 378         if (goto_ch)
 379                 tcf_chain_put_by_act(goto_ch);
 380
 381 release_idr:
 382         tcf_idr_release(*act, bind);
 383         return ret;
 384 }
 385
 386 static void tcf_bpf_cleanup(struct tc_action *act)
 387 {
 388         struct tcf_bpf_cfg tmp;
 389
 390         tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp);
 391         tcf_bpf_cfg_cleanup(&tmp);
 392 }
 393
 394 static struct tc_action_ops act_bpf_ops __read_mostly = {
 395         .kind           =       "bpf",
 396         .id             =       TCA_ID_BPF,
 397         .owner          =       THIS_MODULE,
 398         .act            =       tcf_bpf_act,
 399         .dump           =       tcf_bpf_dump,
 400         .cleanup        =       tcf_bpf_cleanup,
 401         .init           =       tcf_bpf_init,
 402         .size           =       sizeof(struct tcf_bpf),
 403 };
 404
 405 static __net_init int bpf_init_net(struct net *net)
 406 {
 407         struct tc_action_net *tn = net_generic(net, act_bpf_ops.net_id);
 408
 409         return tc_action_net_init(net, tn, &act_bpf_ops);
 410 }
 411
 412 static void __net_exit bpf_exit_net(struct list_head *net_list)
 413 {
 414         tc_action_net_exit(net_list, act_bpf_ops.net_id);
 415 }
 416
 417 static struct pernet_operations bpf_net_ops = {
 418         .init = bpf_init_net,
 419         .exit_batch = bpf_exit_net,
 420         .id   = &act_bpf_ops.net_id,
 421         .size = sizeof(struct tc_action_net),
 422 };
 423
 424 static int __init bpf_init_module(void)
 425 {
 426         return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
 427 }
 428
 429 static void __exit bpf_cleanup_module(void)
 430 {
 431         tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
 432 }
 433
 434 module_init(bpf_init_module);
 435 module_exit(bpf_cleanup_module);
 436
 437 MODULE_AUTHOR("Jiri Pirko <[email protected]>");
 438 MODULE_DESCRIPTION("TC BPF based action");
 439 MODULE_LICENSE("GPL v2");