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         struct tcf_proto        *tp;
  26         struct rcu_head         rcu;
  27 };
  28
  29 static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp,
  30                                struct tcf_result *res)
  31 {
  32         struct cls_cgroup_head *head = rcu_dereference_bh(tp->root);
  33         u32 classid;
  34
  35         classid = task_cls_state(current)->classid;
  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 int cls_cgroup_init(struct tcf_proto *tp)
  71 {
  72         return 0;
  73 }
  74
  75 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
  76         [TCA_CGROUP_EMATCHES]   = { .type = NLA_NESTED },
  77 };
  78
  79 static void cls_cgroup_destroy_rcu(struct rcu_head *root)
  80 {
  81         struct cls_cgroup_head *head = container_of(root,
  82                                                     struct cls_cgroup_head,
  83                                                     rcu);
  84
  85         tcf_exts_destroy(&head->exts);
  86         tcf_em_tree_destroy(&head->ematches);
  87         kfree(head);
  88 }
  89
  90 static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb,
  91                              struct tcf_proto *tp, unsigned long base,
  92                              u32 handle, struct nlattr **tca,
  93                              unsigned long *arg, bool ovr)
  94 {
  95         struct nlattr *tb[TCA_CGROUP_MAX + 1];
  96         struct cls_cgroup_head *head = rtnl_dereference(tp->root);
  97         struct cls_cgroup_head *new;
  98         struct tcf_ematch_tree t;
  99         struct tcf_exts e;
 100         int err;
 101
 102         if (!tca[TCA_OPTIONS])
 103                 return -EINVAL;
 104
 105         if (!head && !handle)
 106                 return -EINVAL;
 107
 108         if (head && handle != head->handle)
 109                 return -ENOENT;
 110
 111         new = kzalloc(sizeof(*head), GFP_KERNEL);
 112         if (!new)
 113                 return -ENOBUFS;
 114
 115         tcf_exts_init(&new->exts, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
 116         new->handle = handle;
 117         new->tp = tp;
 118         err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
 119                                cgroup_policy);
 120         if (err < 0)
 121                 goto errout;
 122
 123         tcf_exts_init(&e, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
 124         err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &e, ovr);
 125         if (err < 0)
 126                 goto errout;
 127
 128         err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
 129         if (err < 0) {
 130                 tcf_exts_destroy(&e);
 131                 goto errout;
 132         }
 133
 134         tcf_exts_change(tp, &new->exts, &e);
 135         tcf_em_tree_change(tp, &new->ematches, &t);
 136
 137         rcu_assign_pointer(tp->root, new);
 138         if (head)
 139                 call_rcu(&head->rcu, cls_cgroup_destroy_rcu);
 140         return 0;
 141 errout:
 142         kfree(new);
 143         return err;
 144 }
 145
 146 static void cls_cgroup_destroy(struct tcf_proto *tp)
 147 {
 148         struct cls_cgroup_head *head = rtnl_dereference(tp->root);
 149
 150         if (head) {
 151                 RCU_INIT_POINTER(tp->root, NULL);
 152                 call_rcu(&head->rcu, cls_cgroup_destroy_rcu);
 153         }
 154 }
 155
 156 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
 157 {
 158         return -EOPNOTSUPP;
 159 }
 160
 161 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 162 {
 163         struct cls_cgroup_head *head = rtnl_dereference(tp->root);
 164
 165         if (arg->count < arg->skip)
 166                 goto skip;
 167
 168         if (arg->fn(tp, (unsigned long) head, arg) < 0) {
 169                 arg->stop = 1;
 170                 return;
 171         }
 172 skip:
 173         arg->count++;
 174 }
 175
 176 static int cls_cgroup_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
 177                            struct sk_buff *skb, struct tcmsg *t)
 178 {
 179         struct cls_cgroup_head *head = rtnl_dereference(tp->root);
 180         unsigned char *b = skb_tail_pointer(skb);
 181         struct nlattr *nest;
 182
 183         t->tcm_handle = head->handle;
 184
 185         nest = nla_nest_start(skb, TCA_OPTIONS);
 186         if (nest == NULL)
 187                 goto nla_put_failure;
 188
 189         if (tcf_exts_dump(skb, &head->exts) < 0 ||
 190             tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
 191                 goto nla_put_failure;
 192
 193         nla_nest_end(skb, nest);
 194
 195         if (tcf_exts_dump_stats(skb, &head->exts) < 0)
 196                 goto nla_put_failure;
 197
 198         return skb->len;
 199
 200 nla_put_failure:
 201         nlmsg_trim(skb, b);
 202         return -1;
 203 }
 204
 205 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
 206         .kind           =       "cgroup",
 207         .init           =       cls_cgroup_init,
 208         .change         =       cls_cgroup_change,
 209         .classify       =       cls_cgroup_classify,
 210         .destroy        =       cls_cgroup_destroy,
 211         .get            =       cls_cgroup_get,
 212         .delete         =       cls_cgroup_delete,
 213         .walk           =       cls_cgroup_walk,
 214         .dump           =       cls_cgroup_dump,
 215         .owner          =       THIS_MODULE,
 216 };
 217
 218 static int __init init_cgroup_cls(void)
 219 {
 220         return register_tcf_proto_ops(&cls_cgroup_ops);
 221 }
 222
 223 static void __exit exit_cgroup_cls(void)
 224 {
 225         unregister_tcf_proto_ops(&cls_cgroup_ops);
 226 }
 227
 228 module_init(init_cgroup_cls);
 229 module_exit(exit_cgroup_cls);
 230 MODULE_LICENSE("GPL");