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