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         rcu_read_lock();
  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 (skb_sk_is_prefetched(skb) && filter_res != TC_ACT_OK)
  58                 skb_orphan(skb);
  59         rcu_read_unlock();
  60
  61         /* A BPF program may overwrite the default action opcode.
  62          * Similarly as in cls_bpf, if filter_res == -1 we use the
  63          * default action specified from tc.
  64          *
  65          * In case a different well-known TC_ACT opcode has been
  66          * returned, it will overwrite the default one.
  67          *
  68          * For everything else that is unknown, TC_ACT_UNSPEC is
  69          * returned.
  70          */
  71         switch (filter_res) {
  72         case TC_ACT_PIPE:
  73         case TC_ACT_RECLASSIFY:
  74         case TC_ACT_OK:
  75         case TC_ACT_REDIRECT:
  76                 action = filter_res;
  77                 break;
  78         case TC_ACT_SHOT:
  79                 action = filter_res;
  80                 qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats));
  81                 break;
  82         case TC_ACT_UNSPEC:
  83                 action = prog->tcf_action;
  84                 break;
  85         default:
  86                 action = TC_ACT_UNSPEC;
  87                 break;
  88         }
  89
  90         return action;
  91 }
  92
  93 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
  94 {
  95         return !prog->bpf_ops;
  96 }
  97
  98 static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog,
  99                                  struct sk_buff *skb)
 100 {
 101         struct nlattr *nla;
 102
 103         if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops))
 104                 return -EMSGSIZE;
 105
 106         nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops *
 107                           sizeof(struct sock_filter));
 108         if (nla == NULL)
 109                 return -EMSGSIZE;
 110
 111         memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
 112
 113         return 0;
 114 }
 115
 116 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
 117                                   struct sk_buff *skb)
 118 {
 119         struct nlattr *nla;
 120
 121         if (prog->bpf_name &&
 122             nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
 123                 return -EMSGSIZE;
 124
 125         if (nla_put_u32(skb, TCA_ACT_BPF_ID, prog->filter->aux->id))
 126                 return -EMSGSIZE;
 127
 128         nla = nla_reserve(skb, TCA_ACT_BPF_TAG, sizeof(prog->filter->tag));
 129         if (nla == NULL)
 130                 return -EMSGSIZE;
 131
 132         memcpy(nla_data(nla), prog->filter->tag, nla_len(nla));
 133
 134         return 0;
 135 }
 136
 137 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
 138                         int bind, int ref)
 139 {
 140         unsigned char *tp = skb_tail_pointer(skb);
 141         struct tcf_bpf *prog = to_bpf(act);
 142         struct tc_act_bpf opt = {
 143                 .index   = prog->tcf_index,
 144                 .refcnt  = refcount_read(&prog->tcf_refcnt) - ref,
 145                 .bindcnt = atomic_read(&prog->tcf_bindcnt) - bind,
 146         };
 147         struct tcf_t tm;
 148         int ret;
 149
 150         spin_lock_bh(&prog->tcf_lock);
 151         opt.action = prog->tcf_action;
 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         spin_unlock_bh(&prog->tcf_lock);
 168         return skb->len;
 169
 170 nla_put_failure:
 171         spin_unlock_bh(&prog->tcf_lock);
 172         nlmsg_trim(skb, tp);
 173         return -1;
 174 }
 175
 176 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
 177         [TCA_ACT_BPF_PARMS]     = { .len = sizeof(struct tc_act_bpf) },
 178         [TCA_ACT_BPF_FD]        = { .type = NLA_U32 },
 179         [TCA_ACT_BPF_NAME]      = { .type = NLA_NUL_STRING,
 180                                     .len = ACT_BPF_NAME_LEN },
 181         [TCA_ACT_BPF_OPS_LEN]   = { .type = NLA_U16 },
 182         [TCA_ACT_BPF_OPS]       = { .type = NLA_BINARY,
 183                                     .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
 184 };
 185
 186 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 187 {
 188         struct sock_filter *bpf_ops;
 189         struct sock_fprog_kern fprog_tmp;
 190         struct bpf_prog *fp;
 191         u16 bpf_size, bpf_num_ops;
 192         int ret;
 193
 194         bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
 195         if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0)
 196                 return -EINVAL;
 197
 198         bpf_size = bpf_num_ops * sizeof(*bpf_ops);
 199         if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
 200                 return -EINVAL;
 201
 202         bpf_ops = kmemdup(nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size, GFP_KERNEL);
 203         if (bpf_ops == NULL)
 204                 return -ENOMEM;
 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         struct bpf_prog *filter = cfg->filter;
 253
 254         if (filter) {
 255                 if (cfg->is_ebpf)
 256                         bpf_prog_put(filter);
 257                 else
 258                         bpf_prog_destroy(filter);
 259         }
 260
 261         kfree(cfg->bpf_ops);
 262         kfree(cfg->bpf_name);
 263 }
 264
 265 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
 266                                   struct tcf_bpf_cfg *cfg)
 267 {
 268         cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
 269         /* updates to prog->filter are prevented, since it's called either
 270          * with tcf lock or during final cleanup in rcu callback
 271          */
 272         cfg->filter = rcu_dereference_protected(prog->filter, 1);
 273
 274         cfg->bpf_ops = prog->bpf_ops;
 275         cfg->bpf_name = prog->bpf_name;
 276 }
 277
 278 static int tcf_bpf_init(struct net *net, struct nlattr *nla,
 279                         struct nlattr *est, struct tc_action **act,
 280                         int replace, int bind, bool rtnl_held,
 281                         struct tcf_proto *tp, u32 flags,
 282                         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         u32 index;
 293
 294         if (!nla)
 295                 return -EINVAL;
 296
 297         ret = nla_parse_nested_deprecated(tb, TCA_ACT_BPF_MAX, nla,
 298                                           act_bpf_policy, NULL);
 299         if (ret < 0)
 300                 return ret;
 301
 302         if (!tb[TCA_ACT_BPF_PARMS])
 303                 return -EINVAL;
 304
 305         parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
 306         index = parm->index;
 307         ret = tcf_idr_check_alloc(tn, &index, act, bind);
 308         if (!ret) {
 309                 ret = tcf_idr_create(tn, index, est, act,
 310                                      &act_bpf_ops, bind, true, 0);
 311                 if (ret < 0) {
 312                         tcf_idr_cleanup(tn, index);
 313                         return ret;
 314                 }
 315
 316                 res = ACT_P_CREATED;
 317         } else if (ret > 0) {
 318                 /* Don't override defaults. */
 319                 if (bind)
 320                         return 0;
 321
 322                 if (!replace) {
 323                         tcf_idr_release(*act, bind);
 324                         return -EEXIST;
 325                 }
 326         } else {
 327                 return ret;
 328         }
 329
 330         ret = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
 331         if (ret < 0)
 332                 goto release_idr;
 333
 334         is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
 335         is_ebpf = tb[TCA_ACT_BPF_FD];
 336
 337         if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) {
 338                 ret = -EINVAL;
 339                 goto put_chain;
 340         }
 341
 342         memset(&cfg, 0, sizeof(cfg));
 343
 344         ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
 345                        tcf_bpf_init_from_efd(tb, &cfg);
 346         if (ret < 0)
 347                 goto put_chain;
 348
 349         prog = to_bpf(*act);
 350
 351         spin_lock_bh(&prog->tcf_lock);
 352         if (res != ACT_P_CREATED)
 353                 tcf_bpf_prog_fill_cfg(prog, &old);
 354
 355         prog->bpf_ops = cfg.bpf_ops;
 356         prog->bpf_name = cfg.bpf_name;
 357
 358         if (cfg.bpf_num_ops)
 359                 prog->bpf_num_ops = cfg.bpf_num_ops;
 360
 361         goto_ch = tcf_action_set_ctrlact(*act, parm->action, goto_ch);
 362         rcu_assign_pointer(prog->filter, cfg.filter);
 363         spin_unlock_bh(&prog->tcf_lock);
 364
 365         if (goto_ch)
 366                 tcf_chain_put_by_act(goto_ch);
 367
 368         if (res != ACT_P_CREATED) {
 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(net, 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");