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
  21 #include <linux/tc_act/tc_bpf.h>
  22 #include <net/tc_act/tc_bpf.h>
  23
  24 #define BPF_TAB_MASK            15
  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         u32 bpf_fd;
  32         u16 bpf_num_ops;
  33         bool is_ebpf;
  34 };
  35
  36 static int bpf_net_id;
  37 static struct tc_action_ops act_bpf_ops;
  38
  39 static int tcf_bpf(struct sk_buff *skb, const struct tc_action *act,
  40                    struct tcf_result *res)
  41 {
  42         struct tcf_bpf *prog = to_bpf(act);
  43         struct bpf_prog *filter;
  44         int action, filter_res;
  45         bool at_ingress = G_TC_AT(skb->tc_verd) & AT_INGRESS;
  46
  47         if (unlikely(!skb_mac_header_was_set(skb)))
  48                 return TC_ACT_UNSPEC;
  49
  50         tcf_lastuse_update(&prog->tcf_tm);
  51         bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb);
  52
  53         rcu_read_lock();
  54         filter = rcu_dereference(prog->filter);
  55         if (at_ingress) {
  56                 __skb_push(skb, skb->mac_len);
  57                 bpf_compute_data_end(skb);
  58                 filter_res = BPF_PROG_RUN(filter, skb);
  59                 __skb_pull(skb, skb->mac_len);
  60         } else {
  61                 bpf_compute_data_end(skb);
  62                 filter_res = BPF_PROG_RUN(filter, skb);
  63         }
  64         rcu_read_unlock();
  65
  66         /* A BPF program may overwrite the default action opcode.
  67          * Similarly as in cls_bpf, if filter_res == -1 we use the
  68          * default action specified from tc.
  69          *
  70          * In case a different well-known TC_ACT opcode has been
  71          * returned, it will overwrite the default one.
  72          *
  73          * For everything else that is unkown, TC_ACT_UNSPEC is
  74          * returned.
  75          */
  76         switch (filter_res) {
  77         case TC_ACT_PIPE:
  78         case TC_ACT_RECLASSIFY:
  79         case TC_ACT_OK:
  80         case TC_ACT_REDIRECT:
  81                 action = filter_res;
  82                 break;
  83         case TC_ACT_SHOT:
  84                 action = filter_res;
  85                 qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats));
  86                 break;
  87         case TC_ACT_UNSPEC:
  88                 action = prog->tcf_action;
  89                 break;
  90         default:
  91                 action = TC_ACT_UNSPEC;
  92                 break;
  93         }
  94
  95         return action;
  96 }
  97
  98 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
  99 {
 100         return !prog->bpf_ops;
 101 }
 102
 103 static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog,
 104                                  struct sk_buff *skb)
 105 {
 106         struct nlattr *nla;
 107
 108         if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops))
 109                 return -EMSGSIZE;
 110
 111         nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops *
 112                           sizeof(struct sock_filter));
 113         if (nla == NULL)
 114                 return -EMSGSIZE;
 115
 116         memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
 117
 118         return 0;
 119 }
 120
 121 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
 122                                   struct sk_buff *skb)
 123 {
 124         if (nla_put_u32(skb, TCA_ACT_BPF_FD, prog->bpf_fd))
 125                 return -EMSGSIZE;
 126
 127         if (prog->bpf_name &&
 128             nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
 129                 return -EMSGSIZE;
 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  = prog->tcf_refcnt - ref,
 142                 .bindcnt = prog->tcf_bindcnt - bind,
 143                 .action  = prog->tcf_action,
 144         };
 145         struct tcf_t tm;
 146         int ret;
 147
 148         if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
 149                 goto nla_put_failure;
 150
 151         if (tcf_bpf_is_ebpf(prog))
 152                 ret = tcf_bpf_dump_ebpf_info(prog, skb);
 153         else
 154                 ret = tcf_bpf_dump_bpf_info(prog, skb);
 155         if (ret)
 156                 goto nla_put_failure;
 157
 158         tcf_tm_dump(&tm, &prog->tcf_tm);
 159         if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm,
 160                           TCA_ACT_BPF_PAD))
 161                 goto nla_put_failure;
 162
 163         return skb->len;
 164
 165 nla_put_failure:
 166         nlmsg_trim(skb, tp);
 167         return -1;
 168 }
 169
 170 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
 171         [TCA_ACT_BPF_PARMS]     = { .len = sizeof(struct tc_act_bpf) },
 172         [TCA_ACT_BPF_FD]        = { .type = NLA_U32 },
 173         [TCA_ACT_BPF_NAME]      = { .type = NLA_NUL_STRING,
 174                                     .len = ACT_BPF_NAME_LEN },
 175         [TCA_ACT_BPF_OPS_LEN]   = { .type = NLA_U16 },
 176         [TCA_ACT_BPF_OPS]       = { .type = NLA_BINARY,
 177                                     .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
 178 };
 179
 180 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 181 {
 182         struct sock_filter *bpf_ops;
 183         struct sock_fprog_kern fprog_tmp;
 184         struct bpf_prog *fp;
 185         u16 bpf_size, bpf_num_ops;
 186         int ret;
 187
 188         bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
 189         if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0)
 190                 return -EINVAL;
 191
 192         bpf_size = bpf_num_ops * sizeof(*bpf_ops);
 193         if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
 194                 return -EINVAL;
 195
 196         bpf_ops = kzalloc(bpf_size, GFP_KERNEL);
 197         if (bpf_ops == NULL)
 198                 return -ENOMEM;
 199
 200         memcpy(bpf_ops, nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size);
 201
 202         fprog_tmp.len = bpf_num_ops;
 203         fprog_tmp.filter = bpf_ops;
 204
 205         ret = bpf_prog_create(&fp, &fprog_tmp);
 206         if (ret < 0) {
 207                 kfree(bpf_ops);
 208                 return ret;
 209         }
 210
 211         cfg->bpf_ops = bpf_ops;
 212         cfg->bpf_num_ops = bpf_num_ops;
 213         cfg->filter = fp;
 214         cfg->is_ebpf = false;
 215
 216         return 0;
 217 }
 218
 219 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 220 {
 221         struct bpf_prog *fp;
 222         char *name = NULL;
 223         u32 bpf_fd;
 224
 225         bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
 226
 227         fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT);
 228         if (IS_ERR(fp))
 229                 return PTR_ERR(fp);
 230
 231         if (tb[TCA_ACT_BPF_NAME]) {
 232                 name = kmemdup(nla_data(tb[TCA_ACT_BPF_NAME]),
 233                                nla_len(tb[TCA_ACT_BPF_NAME]),
 234                                GFP_KERNEL);
 235                 if (!name) {
 236                         bpf_prog_put(fp);
 237                         return -ENOMEM;
 238                 }
 239         }
 240
 241         cfg->bpf_fd = bpf_fd;
 242         cfg->bpf_name = name;
 243         cfg->filter = fp;
 244         cfg->is_ebpf = true;
 245
 246         return 0;
 247 }
 248
 249 static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg)
 250 {
 251         if (cfg->is_ebpf)
 252                 bpf_prog_put(cfg->filter);
 253         else
 254                 bpf_prog_destroy(cfg->filter);
 255
 256         kfree(cfg->bpf_ops);
 257         kfree(cfg->bpf_name);
 258 }
 259
 260 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
 261                                   struct tcf_bpf_cfg *cfg)
 262 {
 263         cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
 264         /* updates to prog->filter are prevented, since it's called either
 265          * with rtnl lock or during final cleanup in rcu callback
 266          */
 267         cfg->filter = rcu_dereference_protected(prog->filter, 1);
 268
 269         cfg->bpf_ops = prog->bpf_ops;
 270         cfg->bpf_name = prog->bpf_name;
 271 }
 272
 273 static int tcf_bpf_init(struct net *net, struct nlattr *nla,
 274                         struct nlattr *est, struct tc_action **act,
 275                         int replace, int bind)
 276 {
 277         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 278         struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
 279         struct tcf_bpf_cfg cfg, old;
 280         struct tc_act_bpf *parm;
 281         struct tcf_bpf *prog;
 282         bool is_bpf, is_ebpf;
 283         int ret, res = 0;
 284
 285         if (!nla)
 286                 return -EINVAL;
 287
 288         ret = nla_parse_nested(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy);
 289         if (ret < 0)
 290                 return ret;
 291
 292         if (!tb[TCA_ACT_BPF_PARMS])
 293                 return -EINVAL;
 294
 295         parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
 296
 297         if (!tcf_hash_check(tn, parm->index, act, bind)) {
 298                 ret = tcf_hash_create(tn, parm->index, est, act,
 299                                       &act_bpf_ops, bind, true);
 300                 if (ret < 0)
 301                         return ret;
 302
 303                 res = ACT_P_CREATED;
 304         } else {
 305                 /* Don't override defaults. */
 306                 if (bind)
 307                         return 0;
 308
 309                 tcf_hash_release(*act, bind);
 310                 if (!replace)
 311                         return -EEXIST;
 312         }
 313
 314         is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
 315         is_ebpf = tb[TCA_ACT_BPF_FD];
 316
 317         if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) {
 318                 ret = -EINVAL;
 319                 goto out;
 320         }
 321
 322         memset(&cfg, 0, sizeof(cfg));
 323
 324         ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
 325                        tcf_bpf_init_from_efd(tb, &cfg);
 326         if (ret < 0)
 327                 goto out;
 328
 329         prog = to_bpf(*act);
 330         ASSERT_RTNL();
 331
 332         if (res != ACT_P_CREATED)
 333                 tcf_bpf_prog_fill_cfg(prog, &old);
 334
 335         prog->bpf_ops = cfg.bpf_ops;
 336         prog->bpf_name = cfg.bpf_name;
 337
 338         if (cfg.bpf_num_ops)
 339                 prog->bpf_num_ops = cfg.bpf_num_ops;
 340         if (cfg.bpf_fd)
 341                 prog->bpf_fd = cfg.bpf_fd;
 342
 343         prog->tcf_action = parm->action;
 344         rcu_assign_pointer(prog->filter, cfg.filter);
 345
 346         if (res == ACT_P_CREATED) {
 347                 tcf_hash_insert(tn, *act);
 348         } else {
 349                 /* make sure the program being replaced is no longer executing */
 350                 synchronize_rcu();
 351                 tcf_bpf_cfg_cleanup(&old);
 352         }
 353
 354         return res;
 355 out:
 356         if (res == ACT_P_CREATED)
 357                 tcf_hash_cleanup(*act, est);
 358
 359         return ret;
 360 }
 361
 362 static void tcf_bpf_cleanup(struct tc_action *act, int bind)
 363 {
 364         struct tcf_bpf_cfg tmp;
 365
 366         tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp);
 367         tcf_bpf_cfg_cleanup(&tmp);
 368 }
 369
 370 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb,
 371                           struct netlink_callback *cb, int type,
 372                           const struct tc_action_ops *ops)
 373 {
 374         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 375
 376         return tcf_generic_walker(tn, skb, cb, type, ops);
 377 }
 378
 379 static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index)
 380 {
 381         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 382
 383         return tcf_hash_search(tn, a, index);
 384 }
 385
 386 static struct tc_action_ops act_bpf_ops __read_mostly = {
 387         .kind           =       "bpf",
 388         .type           =       TCA_ACT_BPF,
 389         .owner          =       THIS_MODULE,
 390         .act            =       tcf_bpf,
 391         .dump           =       tcf_bpf_dump,
 392         .cleanup        =       tcf_bpf_cleanup,
 393         .init           =       tcf_bpf_init,
 394         .walk           =       tcf_bpf_walker,
 395         .lookup         =       tcf_bpf_search,
 396         .size           =       sizeof(struct tcf_bpf),
 397 };
 398
 399 static __net_init int bpf_init_net(struct net *net)
 400 {
 401         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 402
 403         return tc_action_net_init(tn, &act_bpf_ops, BPF_TAB_MASK);
 404 }
 405
 406 static void __net_exit bpf_exit_net(struct net *net)
 407 {
 408         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 409
 410         tc_action_net_exit(tn);
 411 }
 412
 413 static struct pernet_operations bpf_net_ops = {
 414         .init = bpf_init_net,
 415         .exit = bpf_exit_net,
 416         .id   = &bpf_net_id,
 417         .size = sizeof(struct tc_action_net),
 418 };
 419
 420 static int __init bpf_init_module(void)
 421 {
 422         return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
 423 }
 424
 425 static void __exit bpf_cleanup_module(void)
 426 {
 427         tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
 428 }
 429
 430 module_init(bpf_init_module);
 431 module_exit(bpf_cleanup_module);
 432
 433 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
 434 MODULE_DESCRIPTION("TC BPF based action");
 435 MODULE_LICENSE("GPL v2");