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         int action, filter_res;
  41         bool at_ingress = G_TC_AT(skb->tc_verd) & AT_INGRESS;
  42
  43         if (unlikely(!skb_mac_header_was_set(skb)))
  44                 return TC_ACT_UNSPEC;
  45
  46         spin_lock(&prog->tcf_lock);
  47
  48         prog->tcf_tm.lastuse = jiffies;
  49         bstats_update(&prog->tcf_bstats, skb);
  50
  51         /* Needed here for accessing maps. */
  52         rcu_read_lock();
  53         if (at_ingress) {
  54                 __skb_push(skb, skb->mac_len);
  55                 filter_res = BPF_PROG_RUN(prog->filter, skb);
  56                 __skb_pull(skb, skb->mac_len);
  57         } else {
  58                 filter_res = BPF_PROG_RUN(prog->filter, skb);
  59         }
  60         rcu_read_unlock();
  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 unkown, 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                 action = filter_res;
  77                 break;
  78         case TC_ACT_SHOT:
  79                 action = filter_res;
  80                 prog->tcf_qstats.drops++;
  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         spin_unlock(&prog->tcf_lock);
  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         if (nla_put_u32(skb, TCA_ACT_BPF_FD, prog->bpf_fd))
 121                 return -EMSGSIZE;
 122
 123         if (prog->bpf_name &&
 124             nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
 125                 return -EMSGSIZE;
 126
 127         return 0;
 128 }
 129
 130 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
 131                         int bind, int ref)
 132 {
 133         unsigned char *tp = skb_tail_pointer(skb);
 134         struct tcf_bpf *prog = act->priv;
 135         struct tc_act_bpf opt = {
 136                 .index   = prog->tcf_index,
 137                 .refcnt  = prog->tcf_refcnt - ref,
 138                 .bindcnt = prog->tcf_bindcnt - bind,
 139                 .action  = prog->tcf_action,
 140         };
 141         struct tcf_t tm;
 142         int ret;
 143
 144         if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
 145                 goto nla_put_failure;
 146
 147         if (tcf_bpf_is_ebpf(prog))
 148                 ret = tcf_bpf_dump_ebpf_info(prog, skb);
 149         else
 150                 ret = tcf_bpf_dump_bpf_info(prog, skb);
 151         if (ret)
 152                 goto nla_put_failure;
 153
 154         tm.install = jiffies_to_clock_t(jiffies - prog->tcf_tm.install);
 155         tm.lastuse = jiffies_to_clock_t(jiffies - prog->tcf_tm.lastuse);
 156         tm.expires = jiffies_to_clock_t(prog->tcf_tm.expires);
 157
 158         if (nla_put(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm))
 159                 goto nla_put_failure;
 160
 161         return skb->len;
 162
 163 nla_put_failure:
 164         nlmsg_trim(skb, tp);
 165         return -1;
 166 }
 167
 168 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
 169         [TCA_ACT_BPF_PARMS]     = { .len = sizeof(struct tc_act_bpf) },
 170         [TCA_ACT_BPF_FD]        = { .type = NLA_U32 },
 171         [TCA_ACT_BPF_NAME]      = { .type = NLA_NUL_STRING, .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(bpf_fd);
 225         if (IS_ERR(fp))
 226                 return PTR_ERR(fp);
 227
 228         if (fp->type != BPF_PROG_TYPE_SCHED_ACT) {
 229                 bpf_prog_put(fp);
 230                 return -EINVAL;
 231         }
 232
 233         if (tb[TCA_ACT_BPF_NAME]) {
 234                 name = kmemdup(nla_data(tb[TCA_ACT_BPF_NAME]),
 235                                nla_len(tb[TCA_ACT_BPF_NAME]),
 236                                GFP_KERNEL);
 237                 if (!name) {
 238                         bpf_prog_put(fp);
 239                         return -ENOMEM;
 240                 }
 241         }
 242
 243         cfg->bpf_fd = bpf_fd;
 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         if (cfg->is_ebpf)
 254                 bpf_prog_put(cfg->filter);
 255         else
 256                 bpf_prog_destroy(cfg->filter);
 257
 258         kfree(cfg->bpf_ops);
 259         kfree(cfg->bpf_name);
 260 }
 261
 262 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
 263                                   struct tcf_bpf_cfg *cfg)
 264 {
 265         cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
 266         cfg->filter = prog->filter;
 267
 268         cfg->bpf_ops = prog->bpf_ops;
 269         cfg->bpf_name = prog->bpf_name;
 270 }
 271
 272 static int tcf_bpf_init(struct net *net, struct nlattr *nla,
 273                         struct nlattr *est, struct tc_action *act,
 274                         int replace, int bind)
 275 {
 276         struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
 277         struct tcf_bpf_cfg cfg, old;
 278         struct tc_act_bpf *parm;
 279         struct tcf_bpf *prog;
 280         bool is_bpf, is_ebpf;
 281         int ret;
 282
 283         if (!nla)
 284                 return -EINVAL;
 285
 286         ret = nla_parse_nested(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy);
 287         if (ret < 0)
 288                 return ret;
 289
 290         is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
 291         is_ebpf = tb[TCA_ACT_BPF_FD];
 292
 293         if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf) ||
 294             !tb[TCA_ACT_BPF_PARMS])
 295                 return -EINVAL;
 296
 297         parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
 298
 299         memset(&cfg, 0, sizeof(cfg));
 300
 301         ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
 302                        tcf_bpf_init_from_efd(tb, &cfg);
 303         if (ret < 0)
 304                 return ret;
 305
 306         if (!tcf_hash_check(parm->index, act, bind)) {
 307                 ret = tcf_hash_create(parm->index, est, act,
 308                                       sizeof(*prog), bind, false);
 309                 if (ret < 0)
 310                         goto destroy_fp;
 311
 312                 ret = ACT_P_CREATED;
 313         } else {
 314                 /* Don't override defaults. */
 315                 if (bind)
 316                         goto destroy_fp;
 317
 318                 tcf_hash_release(act, bind);
 319                 if (!replace) {
 320                         ret = -EEXIST;
 321                         goto destroy_fp;
 322                 }
 323         }
 324
 325         prog = to_bpf(act);
 326         spin_lock_bh(&prog->tcf_lock);
 327
 328         if (ret != ACT_P_CREATED)
 329                 tcf_bpf_prog_fill_cfg(prog, &old);
 330
 331         prog->bpf_ops = cfg.bpf_ops;
 332         prog->bpf_name = cfg.bpf_name;
 333
 334         if (cfg.bpf_num_ops)
 335                 prog->bpf_num_ops = cfg.bpf_num_ops;
 336         if (cfg.bpf_fd)
 337                 prog->bpf_fd = cfg.bpf_fd;
 338
 339         prog->tcf_action = parm->action;
 340         prog->filter = cfg.filter;
 341
 342         spin_unlock_bh(&prog->tcf_lock);
 343
 344         if (ret == ACT_P_CREATED)
 345                 tcf_hash_insert(act);
 346         else
 347                 tcf_bpf_cfg_cleanup(&old);
 348
 349         return ret;
 350
 351 destroy_fp:
 352         tcf_bpf_cfg_cleanup(&cfg);
 353         return ret;
 354 }
 355
 356 static void tcf_bpf_cleanup(struct tc_action *act, int bind)
 357 {
 358         struct tcf_bpf_cfg tmp;
 359
 360         tcf_bpf_prog_fill_cfg(act->priv, &tmp);
 361         tcf_bpf_cfg_cleanup(&tmp);
 362 }
 363
 364 static struct tc_action_ops act_bpf_ops __read_mostly = {
 365         .kind           =       "bpf",
 366         .type           =       TCA_ACT_BPF,
 367         .owner          =       THIS_MODULE,
 368         .act            =       tcf_bpf,
 369         .dump           =       tcf_bpf_dump,
 370         .cleanup        =       tcf_bpf_cleanup,
 371         .init           =       tcf_bpf_init,
 372 };
 373
 374 static int __init bpf_init_module(void)
 375 {
 376         return tcf_register_action(&act_bpf_ops, BPF_TAB_MASK);
 377 }
 378
 379 static void __exit bpf_cleanup_module(void)
 380 {
 381         tcf_unregister_action(&act_bpf_ops);
 382 }
 383
 384 module_init(bpf_init_module);
 385 module_exit(bpf_cleanup_module);
 386
 387 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
 388 MODULE_DESCRIPTION("TC BPF based action");
 389 MODULE_LICENSE("GPL v2");