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 tcf_bpf(struct sk_buff *skb, const struct tc_action *act,
  37                    struct tcf_result *res)
  38 {
  39         struct tcf_bpf *prog = act->priv;
  40         struct bpf_prog *filter;
  41         int action, filter_res;
  42         bool at_ingress = G_TC_AT(skb->tc_verd) & AT_INGRESS;
  43
  44         if (unlikely(!skb_mac_header_was_set(skb)))
  45                 return TC_ACT_UNSPEC;
  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                 filter_res = BPF_PROG_RUN(filter, skb);
  55                 __skb_pull(skb, skb->mac_len);
  56         } else {
  57                 filter_res = BPF_PROG_RUN(filter, skb);
  58         }
  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 unkown, 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         if (nla_put_u32(skb, TCA_ACT_BPF_FD, prog->bpf_fd))
 120                 return -EMSGSIZE;
 121
 122         if (prog->bpf_name &&
 123             nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
 124                 return -EMSGSIZE;
 125
 126         return 0;
 127 }
 128
 129 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
 130                         int bind, int ref)
 131 {
 132         unsigned char *tp = skb_tail_pointer(skb);
 133         struct tcf_bpf *prog = act->priv;
 134         struct tc_act_bpf opt = {
 135                 .index   = prog->tcf_index,
 136                 .refcnt  = prog->tcf_refcnt - ref,
 137                 .bindcnt = prog->tcf_bindcnt - bind,
 138                 .action  = prog->tcf_action,
 139         };
 140         struct tcf_t tm;
 141         int ret;
 142
 143         if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
 144                 goto nla_put_failure;
 145
 146         if (tcf_bpf_is_ebpf(prog))
 147                 ret = tcf_bpf_dump_ebpf_info(prog, skb);
 148         else
 149                 ret = tcf_bpf_dump_bpf_info(prog, skb);
 150         if (ret)
 151                 goto nla_put_failure;
 152
 153         tm.install = jiffies_to_clock_t(jiffies - prog->tcf_tm.install);
 154         tm.lastuse = jiffies_to_clock_t(jiffies - prog->tcf_tm.lastuse);
 155         tm.expires = jiffies_to_clock_t(prog->tcf_tm.expires);
 156
 157         if (nla_put(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm))
 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, .len = ACT_BPF_NAME_LEN },
 171         [TCA_ACT_BPF_OPS_LEN]   = { .type = NLA_U16 },
 172         [TCA_ACT_BPF_OPS]       = { .type = NLA_BINARY,
 173                                     .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
 174 };
 175
 176 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 177 {
 178         struct sock_filter *bpf_ops;
 179         struct sock_fprog_kern fprog_tmp;
 180         struct bpf_prog *fp;
 181         u16 bpf_size, bpf_num_ops;
 182         int ret;
 183
 184         bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
 185         if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0)
 186                 return -EINVAL;
 187
 188         bpf_size = bpf_num_ops * sizeof(*bpf_ops);
 189         if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
 190                 return -EINVAL;
 191
 192         bpf_ops = kzalloc(bpf_size, GFP_KERNEL);
 193         if (bpf_ops == NULL)
 194                 return -ENOMEM;
 195
 196         memcpy(bpf_ops, nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size);
 197
 198         fprog_tmp.len = bpf_num_ops;
 199         fprog_tmp.filter = bpf_ops;
 200
 201         ret = bpf_prog_create(&fp, &fprog_tmp);
 202         if (ret < 0) {
 203                 kfree(bpf_ops);
 204                 return ret;
 205         }
 206
 207         cfg->bpf_ops = bpf_ops;
 208         cfg->bpf_num_ops = bpf_num_ops;
 209         cfg->filter = fp;
 210         cfg->is_ebpf = false;
 211
 212         return 0;
 213 }
 214
 215 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 216 {
 217         struct bpf_prog *fp;
 218         char *name = NULL;
 219         u32 bpf_fd;
 220
 221         bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
 222
 223         fp = bpf_prog_get(bpf_fd);
 224         if (IS_ERR(fp))
 225                 return PTR_ERR(fp);
 226
 227         if (fp->type != BPF_PROG_TYPE_SCHED_ACT) {
 228                 bpf_prog_put(fp);
 229                 return -EINVAL;
 230         }
 231
 232         if (tb[TCA_ACT_BPF_NAME]) {
 233                 name = kmemdup(nla_data(tb[TCA_ACT_BPF_NAME]),
 234                                nla_len(tb[TCA_ACT_BPF_NAME]),
 235                                GFP_KERNEL);
 236                 if (!name) {
 237                         bpf_prog_put(fp);
 238                         return -ENOMEM;
 239                 }
 240         }
 241
 242         cfg->bpf_fd = bpf_fd;
 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         if (cfg->is_ebpf)
 253                 bpf_prog_put(cfg->filter);
 254         else
 255                 bpf_prog_destroy(cfg->filter);
 256
 257         kfree(cfg->bpf_ops);
 258         kfree(cfg->bpf_name);
 259 }
 260
 261 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
 262                                   struct tcf_bpf_cfg *cfg)
 263 {
 264         cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
 265         /* updates to prog->filter are prevented, since it's called either
 266          * with rtnl lock or during final cleanup in rcu callback
 267          */
 268         cfg->filter = rcu_dereference_protected(prog->filter, 1);
 269
 270         cfg->bpf_ops = prog->bpf_ops;
 271         cfg->bpf_name = prog->bpf_name;
 272 }
 273
 274 static int tcf_bpf_init(struct net *net, struct nlattr *nla,
 275                         struct nlattr *est, struct tc_action *act,
 276                         int replace, int bind)
 277 {
 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(parm->index, act, bind)) {
 298                 ret = tcf_hash_create(parm->index, est, act,
 299                                       sizeof(*prog), 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(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(act->priv, &tmp);
 367         tcf_bpf_cfg_cleanup(&tmp);
 368 }
 369
 370 static struct tc_action_ops act_bpf_ops __read_mostly = {
 371         .kind           =       "bpf",
 372         .type           =       TCA_ACT_BPF,
 373         .owner          =       THIS_MODULE,
 374         .act            =       tcf_bpf,
 375         .dump           =       tcf_bpf_dump,
 376         .cleanup        =       tcf_bpf_cleanup,
 377         .init           =       tcf_bpf_init,
 378 };
 379
 380 static int __init bpf_init_module(void)
 381 {
 382         return tcf_register_action(&act_bpf_ops, BPF_TAB_MASK);
 383 }
 384
 385 static void __exit bpf_cleanup_module(void)
 386 {
 387         tcf_unregister_action(&act_bpf_ops);
 388 }
 389
 390 module_init(bpf_init_module);
 391 module_exit(bpf_cleanup_module);
 392
 393 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
 394 MODULE_DESCRIPTION("TC BPF based action");
 395 MODULE_LICENSE("GPL v2");