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/types.h>
  14 #include <linux/string.h>
  15 #include <linux/errno.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/cgroup.h>
  18 #include <net/rtnetlink.h>
  19 #include <net/pkt_cls.h>
  20
  21 struct cgroup_cls_state
  22 {
  23         struct cgroup_subsys_state css;
  24         u32 classid;
  25 };
  26
  27 static inline struct cgroup_cls_state *net_cls_state(struct cgroup *cgrp)
  28 {
  29         return (struct cgroup_cls_state *)
  30                 cgroup_subsys_state(cgrp, net_cls_subsys_id);
  31 }
  32
  33 static struct cgroup_subsys_state *cgrp_create(struct cgroup_subsys *ss,
  34                                                  struct cgroup *cgrp)
  35 {
  36         struct cgroup_cls_state *cs;
  37
  38         if (!(cs = kzalloc(sizeof(*cs), GFP_KERNEL)))
  39                 return ERR_PTR(-ENOMEM);
  40
  41         if (cgrp->parent)
  42                 cs->classid = net_cls_state(cgrp->parent)->classid;
  43
  44         return &cs->css;
  45 }
  46
  47 static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
  48 {
  49         kfree(ss);
  50 }
  51
  52 static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
  53 {
  54         return net_cls_state(cgrp)->classid;
  55 }
  56
  57 static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
  58 {
  59         if (!cgroup_lock_live_group(cgrp))
  60                 return -ENODEV;
  61
  62         net_cls_state(cgrp)->classid = (u32) value;
  63
  64         cgroup_unlock();
  65
  66         return 0;
  67 }
  68
  69 static struct cftype ss_files[] = {
  70         {
  71                 .name = "classid",
  72                 .read_u64 = read_classid,
  73                 .write_u64 = write_classid,
  74         },
  75 };
  76
  77 static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
  78 {
  79         return cgroup_add_files(cgrp, ss, ss_files, ARRAY_SIZE(ss_files));
  80 }
  81
  82 struct cgroup_subsys net_cls_subsys = {
  83         .name           = "net_cls",
  84         .create         = cgrp_create,
  85         .destroy        = cgrp_destroy,
  86         .populate       = cgrp_populate,
  87         .subsys_id      = net_cls_subsys_id,
  88 };
  89
  90 struct cls_cgroup_head
  91 {
  92         u32                     handle;
  93         struct tcf_exts         exts;
  94         struct tcf_ematch_tree  ematches;
  95 };
  96
  97 static int cls_cgroup_classify(struct sk_buff *skb, struct tcf_proto *tp,
  98                                struct tcf_result *res)
  99 {
 100         struct cls_cgroup_head *head = tp->root;
 101         struct cgroup_cls_state *cs;
 102         int ret = 0;
 103
 104         /*
 105          * Due to the nature of the classifier it is required to ignore all
 106          * packets originating from softirq context as accessing `current'
 107          * would lead to false results.
 108          *
 109          * This test assumes that all callers of dev_queue_xmit() explicitely
 110          * disable bh. Knowing this, it is possible to detect softirq based
 111          * calls by looking at the number of nested bh disable calls because
 112          * softirqs always disables bh.
 113          */
 114         if (softirq_count() != SOFTIRQ_OFFSET)
 115                 return -1;
 116
 117         rcu_read_lock();
 118         cs = (struct cgroup_cls_state *) task_subsys_state(current,
 119                                                            net_cls_subsys_id);
 120         if (cs->classid && tcf_em_tree_match(skb, &head->ematches, NULL)) {
 121                 res->classid = cs->classid;
 122                 res->class = 0;
 123                 ret = tcf_exts_exec(skb, &head->exts, res);
 124         } else
 125                 ret = -1;
 126
 127         rcu_read_unlock();
 128
 129         return ret;
 130 }
 131
 132 static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
 133 {
 134         return 0UL;
 135 }
 136
 137 static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
 138 {
 139 }
 140
 141 static int cls_cgroup_init(struct tcf_proto *tp)
 142 {
 143         return 0;
 144 }
 145
 146 static const struct tcf_ext_map cgroup_ext_map = {
 147         .action = TCA_CGROUP_ACT,
 148         .police = TCA_CGROUP_POLICE,
 149 };
 150
 151 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
 152         [TCA_CGROUP_EMATCHES]   = { .type = NLA_NESTED },
 153 };
 154
 155 static int cls_cgroup_change(struct tcf_proto *tp, unsigned long base,
 156                              u32 handle, struct nlattr **tca,
 157                              unsigned long *arg)
 158 {
 159         struct nlattr *tb[TCA_CGROUP_MAX+1];
 160         struct cls_cgroup_head *head = tp->root;
 161         struct tcf_ematch_tree t;
 162         struct tcf_exts e;
 163         int err;
 164
 165         if (head == NULL) {
 166                 if (!handle)
 167                         return -EINVAL;
 168
 169                 head = kzalloc(sizeof(*head), GFP_KERNEL);
 170                 if (head == NULL)
 171                         return -ENOBUFS;
 172
 173                 head->handle = handle;
 174
 175                 tcf_tree_lock(tp);
 176                 tp->root = head;
 177                 tcf_tree_unlock(tp);
 178         }
 179
 180         if (handle != head->handle)
 181                 return -ENOENT;
 182
 183         err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
 184                                cgroup_policy);
 185         if (err < 0)
 186                 return err;
 187
 188         err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &cgroup_ext_map);
 189         if (err < 0)
 190                 return err;
 191
 192         err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
 193         if (err < 0)
 194                 return err;
 195
 196         tcf_exts_change(tp, &head->exts, &e);
 197         tcf_em_tree_change(tp, &head->ematches, &t);
 198
 199         return 0;
 200 }
 201
 202 static void cls_cgroup_destroy(struct tcf_proto *tp)
 203 {
 204         struct cls_cgroup_head *head = tp->root;
 205
 206         if (head) {
 207                 tcf_exts_destroy(tp, &head->exts);
 208                 tcf_em_tree_destroy(tp, &head->ematches);
 209                 kfree(head);
 210         }
 211 }
 212
 213 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
 214 {
 215         return -EOPNOTSUPP;
 216 }
 217
 218 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 219 {
 220         struct cls_cgroup_head *head = tp->root;
 221
 222         if (arg->count < arg->skip)
 223                 goto skip;
 224
 225         if (arg->fn(tp, (unsigned long) head, arg) < 0) {
 226                 arg->stop = 1;
 227                 return;
 228         }
 229 skip:
 230         arg->count++;
 231 }
 232
 233 static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
 234                            struct sk_buff *skb, struct tcmsg *t)
 235 {
 236         struct cls_cgroup_head *head = tp->root;
 237         unsigned char *b = skb_tail_pointer(skb);
 238         struct nlattr *nest;
 239
 240         t->tcm_handle = head->handle;
 241
 242         nest = nla_nest_start(skb, TCA_OPTIONS);
 243         if (nest == NULL)
 244                 goto nla_put_failure;
 245
 246         if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
 247             tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
 248                 goto nla_put_failure;
 249
 250         nla_nest_end(skb, nest);
 251
 252         if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
 253                 goto nla_put_failure;
 254
 255         return skb->len;
 256
 257 nla_put_failure:
 258         nlmsg_trim(skb, b);
 259         return -1;
 260 }
 261
 262 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
 263         .kind           =       "cgroup",
 264         .init           =       cls_cgroup_init,
 265         .change         =       cls_cgroup_change,
 266         .classify       =       cls_cgroup_classify,
 267         .destroy        =       cls_cgroup_destroy,
 268         .get            =       cls_cgroup_get,
 269         .put            =       cls_cgroup_put,
 270         .delete         =       cls_cgroup_delete,
 271         .walk           =       cls_cgroup_walk,
 272         .dump           =       cls_cgroup_dump,
 273         .owner          =       THIS_MODULE,
 274 };
 275
 276 static int __init init_cgroup_cls(void)
 277 {
 278         return register_tcf_proto_ops(&cls_cgroup_ops);
 279 }
 280
 281 static void __exit exit_cgroup_cls(void)
 282 {
 283         unregister_tcf_proto_ops(&cls_cgroup_ops);
 284 }
 285
 286 module_init(init_cgroup_cls);
 287 module_exit(exit_cgroup_cls);
 288 MODULE_LICENSE("GPL");