kernel/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
  42         if (unlikely(!skb_mac_header_was_set(skb)))
  43                 return TC_ACT_UNSPEC;
  44
  45         spin_lock(&prog->tcf_lock);
  46
  47         prog->tcf_tm.lastuse = jiffies;
  48         bstats_update(&prog->tcf_bstats, skb);
  49
  50         /* Needed here for accessing maps. */
  51         rcu_read_lock();
  52         filter_res = BPF_PROG_RUN(prog->filter, skb);
  53         rcu_read_unlock();
  54
  55         /* A BPF program may overwrite the default action opcode.
  56          * Similarly as in cls_bpf, if filter_res == -1 we use the
  57          * default action specified from tc.
  58          *
  59          * In case a different well-known TC_ACT opcode has been
  60          * returned, it will overwrite the default one.
  61          *
  62          * For everything else that is unkown, TC_ACT_UNSPEC is
  63          * returned.
  64          */
  65         switch (filter_res) {
  66         case TC_ACT_PIPE:
  67         case TC_ACT_RECLASSIFY:
  68         case TC_ACT_OK:
  69                 action = filter_res;
  70                 break;
  71         case TC_ACT_SHOT:
  72                 action = filter_res;
  73                 prog->tcf_qstats.drops++;
  74                 break;
  75         case TC_ACT_UNSPEC:
  76                 action = prog->tcf_action;
  77                 break;
  78         default:
  79                 action = TC_ACT_UNSPEC;
  80                 break;
  81         }
  82
  83         spin_unlock(&prog->tcf_lock);
  84         return action;
  85 }
  86
  87 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
  88 {
  89         return !prog->bpf_ops;
  90 }
  91
  92 static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog,
  93                                  struct sk_buff *skb)
  94 {
  95         struct nlattr *nla;
  96
  97         if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops))
  98                 return -EMSGSIZE;
  99
 100         nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops *
 101                           sizeof(struct sock_filter));
 102         if (nla == NULL)
 103                 return -EMSGSIZE;
 104
 105         memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
 106
 107         return 0;
 108 }
 109
 110 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
 111                                   struct sk_buff *skb)
 112 {
 113         if (nla_put_u32(skb, TCA_ACT_BPF_FD, prog->bpf_fd))
 114                 return -EMSGSIZE;
 115
 116         if (prog->bpf_name &&
 117             nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
 118                 return -EMSGSIZE;
 119
 120         return 0;
 121 }
 122
 123 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
 124                         int bind, int ref)
 125 {
 126         unsigned char *tp = skb_tail_pointer(skb);
 127         struct tcf_bpf *prog = act->priv;
 128         struct tc_act_bpf opt = {
 129                 .index   = prog->tcf_index,
 130                 .refcnt  = prog->tcf_refcnt - ref,
 131                 .bindcnt = prog->tcf_bindcnt - bind,
 132                 .action  = prog->tcf_action,
 133         };
 134         struct tcf_t tm;
 135         int ret;
 136
 137         if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
 138                 goto nla_put_failure;
 139
 140         if (tcf_bpf_is_ebpf(prog))
 141                 ret = tcf_bpf_dump_ebpf_info(prog, skb);
 142         else
 143                 ret = tcf_bpf_dump_bpf_info(prog, skb);
 144         if (ret)
 145                 goto nla_put_failure;
 146
 147         tm.install = jiffies_to_clock_t(jiffies - prog->tcf_tm.install);
 148         tm.lastuse = jiffies_to_clock_t(jiffies - prog->tcf_tm.lastuse);
 149         tm.expires = jiffies_to_clock_t(prog->tcf_tm.expires);
 150
 151         if (nla_put(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm))
 152                 goto nla_put_failure;
 153
 154         return skb->len;
 155
 156 nla_put_failure:
 157         nlmsg_trim(skb, tp);
 158         return -1;
 159 }
 160
 161 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
 162         [TCA_ACT_BPF_PARMS]     = { .len = sizeof(struct tc_act_bpf) },
 163         [TCA_ACT_BPF_FD]        = { .type = NLA_U32 },
 164         [TCA_ACT_BPF_NAME]      = { .type = NLA_NUL_STRING, .len = ACT_BPF_NAME_LEN },
 165         [TCA_ACT_BPF_OPS_LEN]   = { .type = NLA_U16 },
 166         [TCA_ACT_BPF_OPS]       = { .type = NLA_BINARY,
 167                                     .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
 168 };
 169
 170 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 171 {
 172         struct sock_filter *bpf_ops;
 173         struct sock_fprog_kern fprog_tmp;
 174         struct bpf_prog *fp;
 175         u16 bpf_size, bpf_num_ops;
 176         int ret;
 177
 178         bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
 179         if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0)
 180                 return -EINVAL;
 181
 182         bpf_size = bpf_num_ops * sizeof(*bpf_ops);
 183         if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
 184                 return -EINVAL;
 185
 186         bpf_ops = kzalloc(bpf_size, GFP_KERNEL);
 187         if (bpf_ops == NULL)
 188                 return -ENOMEM;
 189
 190         memcpy(bpf_ops, nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size);
 191
 192         fprog_tmp.len = bpf_num_ops;
 193         fprog_tmp.filter = bpf_ops;
 194
 195         ret = bpf_prog_create(&fp, &fprog_tmp);
 196         if (ret < 0) {
 197                 kfree(bpf_ops);
 198                 return ret;
 199         }
 200
 201         cfg->bpf_ops = bpf_ops;
 202         cfg->bpf_num_ops = bpf_num_ops;
 203         cfg->filter = fp;
 204         cfg->is_ebpf = false;
 205
 206         return 0;
 207 }
 208
 209 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 210 {
 211         struct bpf_prog *fp;
 212         char *name = NULL;
 213         u32 bpf_fd;
 214
 215         bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
 216
 217         fp = bpf_prog_get(bpf_fd);
 218         if (IS_ERR(fp))
 219                 return PTR_ERR(fp);
 220
 221         if (fp->type != BPF_PROG_TYPE_SCHED_ACT) {
 222                 bpf_prog_put(fp);
 223                 return -EINVAL;
 224         }
 225
 226         if (tb[TCA_ACT_BPF_NAME]) {
 227                 name = kmemdup(nla_data(tb[TCA_ACT_BPF_NAME]),
 228                                nla_len(tb[TCA_ACT_BPF_NAME]),
 229                                GFP_KERNEL);
 230                 if (!name) {
 231                         bpf_prog_put(fp);
 232                         return -ENOMEM;
 233                 }
 234         }
 235
 236         cfg->bpf_fd = bpf_fd;
 237         cfg->bpf_name = name;
 238         cfg->filter = fp;
 239         cfg->is_ebpf = true;
 240
 241         return 0;
 242 }
 243
 244 static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg)
 245 {
 246         if (cfg->is_ebpf)
 247                 bpf_prog_put(cfg->filter);
 248         else
 249                 bpf_prog_destroy(cfg->filter);
 250
 251         kfree(cfg->bpf_ops);
 252         kfree(cfg->bpf_name);
 253 }
 254
 255 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
 256                                   struct tcf_bpf_cfg *cfg)
 257 {
 258         cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
 259         cfg->filter = prog->filter;
 260
 261         cfg->bpf_ops = prog->bpf_ops;
 262         cfg->bpf_name = prog->bpf_name;
 263 }
 264
 265 static int tcf_bpf_init(struct net *net, struct nlattr *nla,
 266                         struct nlattr *est, struct tc_action *act,
 267                         int replace, int bind)
 268 {
 269         struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
 270         struct tcf_bpf_cfg cfg, old;
 271         struct tc_act_bpf *parm;
 272         struct tcf_bpf *prog;
 273         bool is_bpf, is_ebpf;
 274         int ret;
 275
 276         if (!nla)
 277                 return -EINVAL;
 278
 279         ret = nla_parse_nested(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy);
 280         if (ret < 0)
 281                 return ret;
 282
 283         is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
 284         is_ebpf = tb[TCA_ACT_BPF_FD];
 285
 286         if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf) ||
 287             !tb[TCA_ACT_BPF_PARMS])
 288                 return -EINVAL;
 289
 290         parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
 291
 292         memset(&cfg, 0, sizeof(cfg));
 293
 294         ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
 295                        tcf_bpf_init_from_efd(tb, &cfg);
 296         if (ret < 0)
 297                 return ret;
 298
 299         if (!tcf_hash_check(parm->index, act, bind)) {
 300                 ret = tcf_hash_create(parm->index, est, act,
 301                                       sizeof(*prog), bind);
 302                 if (ret < 0)
 303                         goto destroy_fp;
 304
 305                 ret = ACT_P_CREATED;
 306         } else {
 307                 /* Don't override defaults. */
 308                 if (bind)
 309                         goto destroy_fp;
 310
 311                 tcf_hash_release(act, bind);
 312                 if (!replace) {
 313                         ret = -EEXIST;
 314                         goto destroy_fp;
 315                 }
 316         }
 317
 318         prog = to_bpf(act);
 319         spin_lock_bh(&prog->tcf_lock);
 320
 321         if (ret != ACT_P_CREATED)
 322                 tcf_bpf_prog_fill_cfg(prog, &old);
 323
 324         prog->bpf_ops = cfg.bpf_ops;
 325         prog->bpf_name = cfg.bpf_name;
 326
 327         if (cfg.bpf_num_ops)
 328                 prog->bpf_num_ops = cfg.bpf_num_ops;
 329         if (cfg.bpf_fd)
 330                 prog->bpf_fd = cfg.bpf_fd;
 331
 332         prog->tcf_action = parm->action;
 333         prog->filter = cfg.filter;
 334
 335         spin_unlock_bh(&prog->tcf_lock);
 336
 337         if (ret == ACT_P_CREATED)
 338                 tcf_hash_insert(act);
 339         else
 340                 tcf_bpf_cfg_cleanup(&old);
 341
 342         return ret;
 343
 344 destroy_fp:
 345         tcf_bpf_cfg_cleanup(&cfg);
 346         return ret;
 347 }
 348
 349 static void tcf_bpf_cleanup(struct tc_action *act, int bind)
 350 {
 351         struct tcf_bpf_cfg tmp;
 352
 353         tcf_bpf_prog_fill_cfg(act->priv, &tmp);
 354         tcf_bpf_cfg_cleanup(&tmp);
 355 }
 356
 357 static struct tc_action_ops act_bpf_ops __read_mostly = {
 358         .kind           =       "bpf",
 359         .type           =       TCA_ACT_BPF,
 360         .owner          =       THIS_MODULE,
 361         .act            =       tcf_bpf,
 362         .dump           =       tcf_bpf_dump,
 363         .cleanup        =       tcf_bpf_cleanup,
 364         .init           =       tcf_bpf_init,
 365 };
 366
 367 static int __init bpf_init_module(void)
 368 {
 369         return tcf_register_action(&act_bpf_ops, BPF_TAB_MASK);
 370 }
 371
 372 static void __exit bpf_cleanup_module(void)
 373 {
 374         tcf_unregister_action(&act_bpf_ops);
 375 }
 376
 377 module_init(bpf_init_module);
 378 module_exit(bpf_cleanup_module);
 379
 380 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
 381 MODULE_DESCRIPTION("TC BPF based action");
 382 MODULE_LICENSE("GPL v2");