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 <net/netlink.h>
  17 #include <net/pkt_sched.h>
  18
  19 #include <linux/tc_act/tc_bpf.h>
  20 #include <net/tc_act/tc_bpf.h>
  21
  22 #define BPF_TAB_MASK     15
  23
  24 static int tcf_bpf(struct sk_buff *skb, const struct tc_action *a,
  25                    struct tcf_result *res)
  26 {
  27         struct tcf_bpf *b = a->priv;
  28         int action;
  29         int filter_res;
  30
  31         spin_lock(&b->tcf_lock);
  32         b->tcf_tm.lastuse = jiffies;
  33         bstats_update(&b->tcf_bstats, skb);
  34         action = b->tcf_action;
  35
  36         filter_res = BPF_PROG_RUN(b->filter, skb);
  37         if (filter_res == 0) {
  38                 /* Return code 0 from the BPF program
  39                  * is being interpreted as a drop here.
  40                  */
  41                 action = TC_ACT_SHOT;
  42                 b->tcf_qstats.drops++;
  43         }
  44
  45         spin_unlock(&b->tcf_lock);
  46         return action;
  47 }
  48
  49 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *a,
  50                         int bind, int ref)
  51 {
  52         unsigned char *tp = skb_tail_pointer(skb);
  53         struct tcf_bpf *b = a->priv;
  54         struct tc_act_bpf opt = {
  55                 .index    = b->tcf_index,
  56                 .refcnt   = b->tcf_refcnt - ref,
  57                 .bindcnt  = b->tcf_bindcnt - bind,
  58                 .action   = b->tcf_action,
  59         };
  60         struct tcf_t t;
  61         struct nlattr *nla;
  62
  63         if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
  64                 goto nla_put_failure;
  65
  66         if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, b->bpf_num_ops))
  67                 goto nla_put_failure;
  68
  69         nla = nla_reserve(skb, TCA_ACT_BPF_OPS, b->bpf_num_ops *
  70                           sizeof(struct sock_filter));
  71         if (!nla)
  72                 goto nla_put_failure;
  73
  74         memcpy(nla_data(nla), b->bpf_ops, nla_len(nla));
  75
  76         t.install = jiffies_to_clock_t(jiffies - b->tcf_tm.install);
  77         t.lastuse = jiffies_to_clock_t(jiffies - b->tcf_tm.lastuse);
  78         t.expires = jiffies_to_clock_t(b->tcf_tm.expires);
  79         if (nla_put(skb, TCA_ACT_BPF_TM, sizeof(t), &t))
  80                 goto nla_put_failure;
  81         return skb->len;
  82
  83 nla_put_failure:
  84         nlmsg_trim(skb, tp);
  85         return -1;
  86 }
  87
  88 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
  89         [TCA_ACT_BPF_PARMS]     = { .len = sizeof(struct tc_act_bpf) },
  90         [TCA_ACT_BPF_OPS_LEN]   = { .type = NLA_U16 },
  91         [TCA_ACT_BPF_OPS]       = { .type = NLA_BINARY,
  92                                     .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
  93 };
  94
  95 static int tcf_bpf_init(struct net *net, struct nlattr *nla,
  96                         struct nlattr *est, struct tc_action *a,
  97                         int ovr, int bind)
  98 {
  99         struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
 100         struct tc_act_bpf *parm;
 101         struct tcf_bpf *b;
 102         u16 bpf_size, bpf_num_ops;
 103         struct sock_filter *bpf_ops;
 104         struct sock_fprog_kern tmp;
 105         struct bpf_prog *fp;
 106         int ret;
 107
 108         if (!nla)
 109                 return -EINVAL;
 110
 111         ret = nla_parse_nested(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy);
 112         if (ret < 0)
 113                 return ret;
 114
 115         if (!tb[TCA_ACT_BPF_PARMS] ||
 116             !tb[TCA_ACT_BPF_OPS_LEN] || !tb[TCA_ACT_BPF_OPS])
 117                 return -EINVAL;
 118         parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
 119
 120         bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
 121         if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0)
 122                 return -EINVAL;
 123
 124         bpf_size = bpf_num_ops * sizeof(*bpf_ops);
 125         if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
 126                 return -EINVAL;
 127
 128         bpf_ops = kzalloc(bpf_size, GFP_KERNEL);
 129         if (!bpf_ops)
 130                 return -ENOMEM;
 131
 132         memcpy(bpf_ops, nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size);
 133
 134         tmp.len = bpf_num_ops;
 135         tmp.filter = bpf_ops;
 136
 137         ret = bpf_prog_create(&fp, &tmp);
 138         if (ret)
 139                 goto free_bpf_ops;
 140
 141         if (!tcf_hash_check(parm->index, a, bind)) {
 142                 ret = tcf_hash_create(parm->index, est, a, sizeof(*b), bind);
 143                 if (ret)
 144                         goto destroy_fp;
 145
 146                 ret = ACT_P_CREATED;
 147         } else {
 148                 if (bind)
 149                         goto destroy_fp;
 150                 tcf_hash_release(a, bind);
 151                 if (!ovr) {
 152                         ret = -EEXIST;
 153                         goto destroy_fp;
 154                 }
 155         }
 156
 157         b = to_bpf(a);
 158         spin_lock_bh(&b->tcf_lock);
 159         b->tcf_action = parm->action;
 160         b->bpf_num_ops = bpf_num_ops;
 161         b->bpf_ops = bpf_ops;
 162         b->filter = fp;
 163         spin_unlock_bh(&b->tcf_lock);
 164
 165         if (ret == ACT_P_CREATED)
 166                 tcf_hash_insert(a);
 167         return ret;
 168
 169 destroy_fp:
 170         bpf_prog_destroy(fp);
 171 free_bpf_ops:
 172         kfree(bpf_ops);
 173         return ret;
 174 }
 175
 176 static void tcf_bpf_cleanup(struct tc_action *a, int bind)
 177 {
 178         struct tcf_bpf *b = a->priv;
 179
 180         bpf_prog_destroy(b->filter);
 181 }
 182
 183 static struct tc_action_ops act_bpf_ops = {
 184         .kind =         "bpf",
 185         .type =         TCA_ACT_BPF,
 186         .owner =        THIS_MODULE,
 187         .act =          tcf_bpf,
 188         .dump =         tcf_bpf_dump,
 189         .cleanup =      tcf_bpf_cleanup,
 190         .init =         tcf_bpf_init,
 191 };
 192
 193 static int __init bpf_init_module(void)
 194 {
 195         return tcf_register_action(&act_bpf_ops, BPF_TAB_MASK);
 196 }
 197
 198 static void __exit bpf_cleanup_module(void)
 199 {
 200         tcf_unregister_action(&act_bpf_ops);
 201 }
 202
 203 module_init(bpf_init_module);
 204 module_exit(bpf_cleanup_module);
 205
 206 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
 207 MODULE_DESCRIPTION("TC BPF based action");
 208 MODULE_LICENSE("GPL v2");