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         bool at_ingress = skb_at_tc_ingress(skb);
  43         struct tcf_bpf *prog = to_bpf(act);
  44         struct bpf_prog *filter;
  45         int action, filter_res;
  46
  47         tcf_lastuse_update(&prog->tcf_tm);
  48         bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb);
  49
  50         rcu_read_lock();
  51         filter = rcu_dereference(prog->filter);
  52         if (at_ingress) {
  53                 __skb_push(skb, skb->mac_len);
  54                 bpf_compute_data_end(skb);
  55                 filter_res = BPF_PROG_RUN(filter, skb);
  56                 __skb_pull(skb, skb->mac_len);
  57         } else {
  58                 bpf_compute_data_end(skb);
  59                 filter_res = BPF_PROG_RUN(filter, skb);
  60         }
  61         rcu_read_unlock();
  62
  63         /* A BPF program may overwrite the default action opcode.
  64          * Similarly as in cls_bpf, if filter_res == -1 we use the
  65          * default action specified from tc.
  66          *
  67          * In case a different well-known TC_ACT opcode has been
  68          * returned, it will overwrite the default one.
  69          *
  70          * For everything else that is unkown, TC_ACT_UNSPEC is
  71          * returned.
  72          */
  73         switch (filter_res) {
  74         case TC_ACT_PIPE:
  75         case TC_ACT_RECLASSIFY:
  76         case TC_ACT_OK:
  77         case TC_ACT_REDIRECT:
  78                 action = filter_res;
  79                 break;
  80         case TC_ACT_SHOT:
  81                 action = filter_res;
  82                 qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats));
  83                 break;
  84         case TC_ACT_UNSPEC:
  85                 action = prog->tcf_action;
  86                 break;
  87         default:
  88                 action = TC_ACT_UNSPEC;
  89                 break;
  90         }
  91
  92         return action;
  93 }
  94
  95 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
  96 {
  97         return !prog->bpf_ops;
  98 }
  99
 100 static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog,
 101                                  struct sk_buff *skb)
 102 {
 103         struct nlattr *nla;
 104
 105         if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops))
 106                 return -EMSGSIZE;
 107
 108         nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops *
 109                           sizeof(struct sock_filter));
 110         if (nla == NULL)
 111                 return -EMSGSIZE;
 112
 113         memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
 114
 115         return 0;
 116 }
 117
 118 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
 119                                   struct sk_buff *skb)
 120 {
 121         if (nla_put_u32(skb, TCA_ACT_BPF_FD, prog->bpf_fd))
 122                 return -EMSGSIZE;
 123
 124         if (prog->bpf_name &&
 125             nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
 126                 return -EMSGSIZE;
 127
 128         return 0;
 129 }
 130
 131 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
 132                         int bind, int ref)
 133 {
 134         unsigned char *tp = skb_tail_pointer(skb);
 135         struct tcf_bpf *prog = to_bpf(act);
 136         struct tc_act_bpf opt = {
 137                 .index   = prog->tcf_index,
 138                 .refcnt  = prog->tcf_refcnt - ref,
 139                 .bindcnt = prog->tcf_bindcnt - bind,
 140                 .action  = prog->tcf_action,
 141         };
 142         struct tcf_t tm;
 143         int ret;
 144
 145         if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
 146                 goto nla_put_failure;
 147
 148         if (tcf_bpf_is_ebpf(prog))
 149                 ret = tcf_bpf_dump_ebpf_info(prog, skb);
 150         else
 151                 ret = tcf_bpf_dump_bpf_info(prog, skb);
 152         if (ret)
 153                 goto nla_put_failure;
 154
 155         tcf_tm_dump(&tm, &prog->tcf_tm);
 156         if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm,
 157                           TCA_ACT_BPF_PAD))
 158                 goto nla_put_failure;
 159
 160         return skb->len;
 161
 162 nla_put_failure:
 163         nlmsg_trim(skb, tp);
 164         return -1;
 165 }
 166
 167 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
 168         [TCA_ACT_BPF_PARMS]     = { .len = sizeof(struct tc_act_bpf) },
 169         [TCA_ACT_BPF_FD]        = { .type = NLA_U32 },
 170         [TCA_ACT_BPF_NAME]      = { .type = NLA_NUL_STRING,
 171                                     .len = ACT_BPF_NAME_LEN },
 172         [TCA_ACT_BPF_OPS_LEN]   = { .type = NLA_U16 },
 173         [TCA_ACT_BPF_OPS]       = { .type = NLA_BINARY,
 174                                     .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
 175 };
 176
 177 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 178 {
 179         struct sock_filter *bpf_ops;
 180         struct sock_fprog_kern fprog_tmp;
 181         struct bpf_prog *fp;
 182         u16 bpf_size, bpf_num_ops;
 183         int ret;
 184
 185         bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
 186         if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0)
 187                 return -EINVAL;
 188
 189         bpf_size = bpf_num_ops * sizeof(*bpf_ops);
 190         if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
 191                 return -EINVAL;
 192
 193         bpf_ops = kzalloc(bpf_size, GFP_KERNEL);
 194         if (bpf_ops == NULL)
 195                 return -ENOMEM;
 196
 197         memcpy(bpf_ops, nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size);
 198
 199         fprog_tmp.len = bpf_num_ops;
 200         fprog_tmp.filter = bpf_ops;
 201
 202         ret = bpf_prog_create(&fp, &fprog_tmp);
 203         if (ret < 0) {
 204                 kfree(bpf_ops);
 205                 return ret;
 206         }
 207
 208         cfg->bpf_ops = bpf_ops;
 209         cfg->bpf_num_ops = bpf_num_ops;
 210         cfg->filter = fp;
 211         cfg->is_ebpf = false;
 212
 213         return 0;
 214 }
 215
 216 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 217 {
 218         struct bpf_prog *fp;
 219         char *name = NULL;
 220         u32 bpf_fd;
 221
 222         bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
 223
 224         fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT);
 225         if (IS_ERR(fp))
 226                 return PTR_ERR(fp);
 227
 228         if (tb[TCA_ACT_BPF_NAME]) {
 229                 name = kmemdup(nla_data(tb[TCA_ACT_BPF_NAME]),
 230                                nla_len(tb[TCA_ACT_BPF_NAME]),
 231                                GFP_KERNEL);
 232                 if (!name) {
 233                         bpf_prog_put(fp);
 234                         return -ENOMEM;
 235                 }
 236         }
 237
 238         cfg->bpf_fd = bpf_fd;
 239         cfg->bpf_name = name;
 240         cfg->filter = fp;
 241         cfg->is_ebpf = true;
 242
 243         return 0;
 244 }
 245
 246 static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg)
 247 {
 248         if (cfg->is_ebpf)
 249                 bpf_prog_put(cfg->filter);
 250         else
 251                 bpf_prog_destroy(cfg->filter);
 252
 253         kfree(cfg->bpf_ops);
 254         kfree(cfg->bpf_name);
 255 }
 256
 257 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
 258                                   struct tcf_bpf_cfg *cfg)
 259 {
 260         cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
 261         /* updates to prog->filter are prevented, since it's called either
 262          * with rtnl lock or during final cleanup in rcu callback
 263          */
 264         cfg->filter = rcu_dereference_protected(prog->filter, 1);
 265
 266         cfg->bpf_ops = prog->bpf_ops;
 267         cfg->bpf_name = prog->bpf_name;
 268 }
 269
 270 static int tcf_bpf_init(struct net *net, struct nlattr *nla,
 271                         struct nlattr *est, struct tc_action **act,
 272                         int replace, int bind)
 273 {
 274         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 275         struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
 276         struct tcf_bpf_cfg cfg, old;
 277         struct tc_act_bpf *parm;
 278         struct tcf_bpf *prog;
 279         bool is_bpf, is_ebpf;
 280         int ret, res = 0;
 281
 282         if (!nla)
 283                 return -EINVAL;
 284
 285         ret = nla_parse_nested(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy);
 286         if (ret < 0)
 287                 return ret;
 288
 289         if (!tb[TCA_ACT_BPF_PARMS])
 290                 return -EINVAL;
 291
 292         parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
 293
 294         if (!tcf_hash_check(tn, parm->index, act, bind)) {
 295                 ret = tcf_hash_create(tn, parm->index, est, act,
 296                                       &act_bpf_ops, bind, true);
 297                 if (ret < 0)
 298                         return ret;
 299
 300                 res = ACT_P_CREATED;
 301         } else {
 302                 /* Don't override defaults. */
 303                 if (bind)
 304                         return 0;
 305
 306                 tcf_hash_release(*act, bind);
 307                 if (!replace)
 308                         return -EEXIST;
 309         }
 310
 311         is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
 312         is_ebpf = tb[TCA_ACT_BPF_FD];
 313
 314         if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) {
 315                 ret = -EINVAL;
 316                 goto out;
 317         }
 318
 319         memset(&cfg, 0, sizeof(cfg));
 320
 321         ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
 322                        tcf_bpf_init_from_efd(tb, &cfg);
 323         if (ret < 0)
 324                 goto out;
 325
 326         prog = to_bpf(*act);
 327         ASSERT_RTNL();
 328
 329         if (res != ACT_P_CREATED)
 330                 tcf_bpf_prog_fill_cfg(prog, &old);
 331
 332         prog->bpf_ops = cfg.bpf_ops;
 333         prog->bpf_name = cfg.bpf_name;
 334
 335         if (cfg.bpf_num_ops)
 336                 prog->bpf_num_ops = cfg.bpf_num_ops;
 337         if (cfg.bpf_fd)
 338                 prog->bpf_fd = cfg.bpf_fd;
 339
 340         prog->tcf_action = parm->action;
 341         rcu_assign_pointer(prog->filter, cfg.filter);
 342
 343         if (res == ACT_P_CREATED) {
 344                 tcf_hash_insert(tn, *act);
 345         } else {
 346                 /* make sure the program being replaced is no longer executing */
 347                 synchronize_rcu();
 348                 tcf_bpf_cfg_cleanup(&old);
 349         }
 350
 351         return res;
 352 out:
 353         if (res == ACT_P_CREATED)
 354                 tcf_hash_cleanup(*act, est);
 355
 356         return ret;
 357 }
 358
 359 static void tcf_bpf_cleanup(struct tc_action *act, int bind)
 360 {
 361         struct tcf_bpf_cfg tmp;
 362
 363         tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp);
 364         tcf_bpf_cfg_cleanup(&tmp);
 365 }
 366
 367 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb,
 368                           struct netlink_callback *cb, int type,
 369                           const struct tc_action_ops *ops)
 370 {
 371         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 372
 373         return tcf_generic_walker(tn, skb, cb, type, ops);
 374 }
 375
 376 static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index)
 377 {
 378         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 379
 380         return tcf_hash_search(tn, a, index);
 381 }
 382
 383 static struct tc_action_ops act_bpf_ops __read_mostly = {
 384         .kind           =       "bpf",
 385         .type           =       TCA_ACT_BPF,
 386         .owner          =       THIS_MODULE,
 387         .act            =       tcf_bpf,
 388         .dump           =       tcf_bpf_dump,
 389         .cleanup        =       tcf_bpf_cleanup,
 390         .init           =       tcf_bpf_init,
 391         .walk           =       tcf_bpf_walker,
 392         .lookup         =       tcf_bpf_search,
 393         .size           =       sizeof(struct tcf_bpf),
 394 };
 395
 396 static __net_init int bpf_init_net(struct net *net)
 397 {
 398         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 399
 400         return tc_action_net_init(tn, &act_bpf_ops, BPF_TAB_MASK);
 401 }
 402
 403 static void __net_exit bpf_exit_net(struct net *net)
 404 {
 405         struct tc_action_net *tn = net_generic(net, bpf_net_id);
 406
 407         tc_action_net_exit(tn);
 408 }
 409
 410 static struct pernet_operations bpf_net_ops = {
 411         .init = bpf_init_net,
 412         .exit = bpf_exit_net,
 413         .id   = &bpf_net_id,
 414         .size = sizeof(struct tc_action_net),
 415 };
 416
 417 static int __init bpf_init_module(void)
 418 {
 419         return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
 420 }
 421
 422 static void __exit bpf_cleanup_module(void)
 423 {
 424         tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
 425 }
 426
 427 module_init(bpf_init_module);
 428 module_exit(bpf_cleanup_module);
 429
 430 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
 431 MODULE_DESCRIPTION("TC BPF based action");
 432 MODULE_LICENSE("GPL v2");