net/sched/cls_cgroup.c

   1 /*
   2  * net/sched/cls_cgroup.c       Control Group Classifier
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Thomas Graf <tgraf@suug.ch>
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/rcupdate.h>
  16 #include <net/rtnetlink.h>
  17 #include <net/pkt_cls.h>
  18 #include <net/sock.h>
  19 #include <net/cls_cgroup.h>
  20
  21 struct cls_cgroup_head {
  22         u32                     handle;
  23         struct tcf_exts         exts;
  24         struct tcf_ematch_tree  ematches;
  25 };
  26
  27 static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp,
  28                                struct tcf_result *res)
  29 {
  30         struct cls_cgroup_head *head = tp->root;
  31         u32 classid;
  32
  33         rcu_read_lock();
  34         classid = task_cls_state(current)->classid;
  35         rcu_read_unlock();
  36
  37         /*
  38          * Due to the nature of the classifier it is required to ignore all
  39          * packets originating from softirq context as accessing `current'
  40          * would lead to false results.
  41          *
  42          * This test assumes that all callers of dev_queue_xmit() explicitely
  43          * disable bh. Knowing this, it is possible to detect softirq based
  44          * calls by looking at the number of nested bh disable calls because
  45          * softirqs always disables bh.
  46          */
  47         if (in_serving_softirq()) {
  48                 /* If there is an sk_classid we'll use that. */
  49                 if (!skb->sk)
  50                         return -1;
  51                 classid = skb->sk->sk_classid;
  52         }
  53
  54         if (!classid)
  55                 return -1;
  56
  57         if (!tcf_em_tree_match(skb, &head->ematches, NULL))
  58                 return -1;
  59
  60         res->classid = classid;
  61         res->class = 0;
  62         return tcf_exts_exec(skb, &head->exts, res);
  63 }
  64
  65 static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
  66 {
  67         return 0UL;
  68 }
  69
  70 static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
  71 {
  72 }
  73
  74 static int cls_cgroup_init(struct tcf_proto *tp)
  75 {
  76         return 0;
  77 }
  78
  79 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
  80         [TCA_CGROUP_EMATCHES]   = { .type = NLA_NESTED },
  81 };
  82
  83 static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb,
  84                              struct tcf_proto *tp, unsigned long base,
  85                              u32 handle, struct nlattr **tca,
  86                              unsigned long *arg, bool ovr)
  87 {
  88         struct nlattr *tb[TCA_CGROUP_MAX + 1];
  89         struct cls_cgroup_head *head = tp->root;
  90         struct tcf_ematch_tree t;
  91         struct tcf_exts e;
  92         int err;
  93
  94         if (!tca[TCA_OPTIONS])
  95                 return -EINVAL;
  96
  97         if (head == NULL) {
  98                 if (!handle)
  99                         return -EINVAL;
 100
 101                 head = kzalloc(sizeof(*head), GFP_KERNEL);
 102                 if (head == NULL)
 103                         return -ENOBUFS;
 104
 105                 tcf_exts_init(&head->exts, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
 106                 head->handle = handle;
 107
 108                 tcf_tree_lock(tp);
 109                 tp->root = head;
 110                 tcf_tree_unlock(tp);
 111         }
 112
 113         if (handle != head->handle)
 114                 return -ENOENT;
 115
 116         err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
 117                                cgroup_policy);
 118         if (err < 0)
 119                 return err;
 120
 121         tcf_exts_init(&e, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
 122         err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &e, ovr);
 123         if (err < 0)
 124                 return err;
 125
 126         err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
 127         if (err < 0)
 128                 return err;
 129
 130         tcf_exts_change(tp, &head->exts, &e);
 131         tcf_em_tree_change(tp, &head->ematches, &t);
 132
 133         return 0;
 134 }
 135
 136 static void cls_cgroup_destroy(struct tcf_proto *tp)
 137 {
 138         struct cls_cgroup_head *head = tp->root;
 139
 140         if (head) {
 141                 tcf_exts_destroy(tp, &head->exts);
 142                 tcf_em_tree_destroy(tp, &head->ematches);
 143                 kfree(head);
 144         }
 145 }
 146
 147 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
 148 {
 149         return -EOPNOTSUPP;
 150 }
 151
 152 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 153 {
 154         struct cls_cgroup_head *head = tp->root;
 155
 156         if (arg->count < arg->skip)
 157                 goto skip;
 158
 159         if (arg->fn(tp, (unsigned long) head, arg) < 0) {
 160                 arg->stop = 1;
 161                 return;
 162         }
 163 skip:
 164         arg->count++;
 165 }
 166
 167 static int cls_cgroup_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
 168                            struct sk_buff *skb, struct tcmsg *t)
 169 {
 170         struct cls_cgroup_head *head = tp->root;
 171         unsigned char *b = skb_tail_pointer(skb);
 172         struct nlattr *nest;
 173
 174         t->tcm_handle = head->handle;
 175
 176         nest = nla_nest_start(skb, TCA_OPTIONS);
 177         if (nest == NULL)
 178                 goto nla_put_failure;
 179
 180         if (tcf_exts_dump(skb, &head->exts) < 0 ||
 181             tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
 182                 goto nla_put_failure;
 183
 184         nla_nest_end(skb, nest);
 185
 186         if (tcf_exts_dump_stats(skb, &head->exts) < 0)
 187                 goto nla_put_failure;
 188
 189         return skb->len;
 190
 191 nla_put_failure:
 192         nlmsg_trim(skb, b);
 193         return -1;
 194 }
 195
 196 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
 197         .kind           =       "cgroup",
 198         .init           =       cls_cgroup_init,
 199         .change         =       cls_cgroup_change,
 200         .classify       =       cls_cgroup_classify,
 201         .destroy        =       cls_cgroup_destroy,
 202         .get            =       cls_cgroup_get,
 203         .put            =       cls_cgroup_put,
 204         .delete         =       cls_cgroup_delete,
 205         .walk           =       cls_cgroup_walk,
 206         .dump           =       cls_cgroup_dump,
 207         .owner          =       THIS_MODULE,
 208 };
 209
 210 static int __init init_cgroup_cls(void)
 211 {
 212         return register_tcf_proto_ops(&cls_cgroup_ops);
 213 }
 214
 215 static void __exit exit_cgroup_cls(void)
 216 {
 217         unregister_tcf_proto_ops(&cls_cgroup_ops);
 218 }
 219
 220 module_init(init_cgroup_cls);
 221 module_exit(exit_cgroup_cls);
 222 MODULE_LICENSE("GPL");