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 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 void cls_cgroup_destroy_rcu(struct rcu_head *root)
  84 {
  85         struct cls_cgroup_head *head = container_of(root,
  86                                                     struct cls_cgroup_head,
  87                                                     rcu);
  88
  89         tcf_exts_destroy(head->tp, &head->exts);
  90         tcf_em_tree_destroy(head->tp, &head->ematches);
  91         kfree(head);
  92 }
  93
  94 static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb,
  95                              struct tcf_proto *tp, unsigned long base,
  96                              u32 handle, struct nlattr **tca,
  97                              unsigned long *arg, bool ovr)
  98 {
  99         struct nlattr *tb[TCA_CGROUP_MAX + 1];
 100         struct cls_cgroup_head *head = rtnl_dereference(tp->root);
 101         struct cls_cgroup_head *new;
 102         struct tcf_ematch_tree t;
 103         struct tcf_exts e;
 104         int err;
 105
 106         if (!tca[TCA_OPTIONS])
 107                 return -EINVAL;
 108
 109         if (!head && !handle)
 110                 return -EINVAL;
 111
 112         if (head && handle != head->handle)
 113                 return -ENOENT;
 114
 115         new = kzalloc(sizeof(*head), GFP_KERNEL);
 116         if (!new)
 117                 return -ENOBUFS;
 118
 119         if (head) {
 120                 new->handle = head->handle;
 121         } else {
 122                 tcf_exts_init(&new->exts, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
 123                 new->handle = handle;
 124         }
 125
 126         new->tp = tp;
 127         err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
 128                                cgroup_policy);
 129         if (err < 0)
 130                 return err;
 131
 132         tcf_exts_init(&e, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
 133         err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &e, ovr);
 134         if (err < 0)
 135                 return err;
 136
 137         err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
 138         if (err < 0)
 139                 return err;
 140
 141         tcf_exts_change(tp, &new->exts, &e);
 142         tcf_em_tree_change(tp, &new->ematches, &t);
 143
 144         rcu_assign_pointer(tp->root, new);
 145         if (head)
 146                 call_rcu(&head->rcu, cls_cgroup_destroy_rcu);
 147         return 0;
 148 }
 149
 150 static void cls_cgroup_destroy(struct tcf_proto *tp)
 151 {
 152         struct cls_cgroup_head *head = rtnl_dereference(tp->root);
 153
 154         if (head) {
 155                 tcf_exts_destroy(tp, &head->exts);
 156                 tcf_em_tree_destroy(tp, &head->ematches);
 157                 RCU_INIT_POINTER(tp->root, NULL);
 158                 kfree_rcu(head, rcu);
 159         }
 160 }
 161
 162 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
 163 {
 164         return -EOPNOTSUPP;
 165 }
 166
 167 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 168 {
 169         struct cls_cgroup_head *head = rtnl_dereference(tp->root);
 170
 171         if (arg->count < arg->skip)
 172                 goto skip;
 173
 174         if (arg->fn(tp, (unsigned long) head, arg) < 0) {
 175                 arg->stop = 1;
 176                 return;
 177         }
 178 skip:
 179         arg->count++;
 180 }
 181
 182 static int cls_cgroup_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
 183                            struct sk_buff *skb, struct tcmsg *t)
 184 {
 185         struct cls_cgroup_head *head = rtnl_dereference(tp->root);
 186         unsigned char *b = skb_tail_pointer(skb);
 187         struct nlattr *nest;
 188
 189         t->tcm_handle = head->handle;
 190
 191         nest = nla_nest_start(skb, TCA_OPTIONS);
 192         if (nest == NULL)
 193                 goto nla_put_failure;
 194
 195         if (tcf_exts_dump(skb, &head->exts) < 0 ||
 196             tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
 197                 goto nla_put_failure;
 198
 199         nla_nest_end(skb, nest);
 200
 201         if (tcf_exts_dump_stats(skb, &head->exts) < 0)
 202                 goto nla_put_failure;
 203
 204         return skb->len;
 205
 206 nla_put_failure:
 207         nlmsg_trim(skb, b);
 208         return -1;
 209 }
 210
 211 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
 212         .kind           =       "cgroup",
 213         .init           =       cls_cgroup_init,
 214         .change         =       cls_cgroup_change,
 215         .classify       =       cls_cgroup_classify,
 216         .destroy        =       cls_cgroup_destroy,
 217         .get            =       cls_cgroup_get,
 218         .put            =       cls_cgroup_put,
 219         .delete         =       cls_cgroup_delete,
 220         .walk           =       cls_cgroup_walk,
 221         .dump           =       cls_cgroup_dump,
 222         .owner          =       THIS_MODULE,
 223 };
 224
 225 static int __init init_cgroup_cls(void)
 226 {
 227         return register_tcf_proto_ops(&cls_cgroup_ops);
 228 }
 229
 230 static void __exit exit_cgroup_cls(void)
 231 {
 232         unregister_tcf_proto_ops(&cls_cgroup_ops);
 233 }
 234
 235 module_init(init_cgroup_cls);
 236 module_exit(exit_cgroup_cls);
 237 MODULE_LICENSE("GPL");