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   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/types.h>
  15 #include <linux/string.h>
  16 #include <linux/errno.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/cgroup.h>
  19 #include <net/rtnetlink.h>
  20 #include <net/pkt_cls.h>
  21
  22 struct cgroup_cls_state
  23 {
  24         struct cgroup_subsys_state css;
  25         u32 classid;
  26 };
  27
  28 static struct cgroup_subsys_state *cgrp_create(struct cgroup_subsys *ss,
  29                                                struct cgroup *cgrp);
  30 static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp);
  31 static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp);
  32
  33 struct cgroup_subsys net_cls_subsys = {
  34         .name           = "net_cls",
  35         .create         = cgrp_create,
  36         .destroy        = cgrp_destroy,
  37         .populate       = cgrp_populate,
  38 #ifdef CONFIG_NET_CLS_CGROUP
  39         .subsys_id      = net_cls_subsys_id,
  40 #else
  41 #define net_cls_subsys_id net_cls_subsys.subsys_id
  42 #endif
  43         .module         = THIS_MODULE,
  44 };
  45
  46
  47 static inline struct cgroup_cls_state *cgrp_cls_state(struct cgroup *cgrp)
  48 {
  49         return container_of(cgroup_subsys_state(cgrp, net_cls_subsys_id),
  50                             struct cgroup_cls_state, css);
  51 }
  52
  53 static inline struct cgroup_cls_state *task_cls_state(struct task_struct *p)
  54 {
  55         return container_of(task_subsys_state(p, net_cls_subsys_id),
  56                             struct cgroup_cls_state, css);
  57 }
  58
  59 static struct cgroup_subsys_state *cgrp_create(struct cgroup_subsys *ss,
  60                                                  struct cgroup *cgrp)
  61 {
  62         struct cgroup_cls_state *cs;
  63
  64         if (!(cs = kzalloc(sizeof(*cs), GFP_KERNEL)))
  65                 return ERR_PTR(-ENOMEM);
  66
  67         if (cgrp->parent)
  68                 cs->classid = cgrp_cls_state(cgrp->parent)->classid;
  69
  70         return &cs->css;
  71 }
  72
  73 static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
  74 {
  75         kfree(cgrp_cls_state(cgrp));
  76 }
  77
  78 static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
  79 {
  80         return cgrp_cls_state(cgrp)->classid;
  81 }
  82
  83 static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
  84 {
  85         cgrp_cls_state(cgrp)->classid = (u32) value;
  86         return 0;
  87 }
  88
  89 static struct cftype ss_files[] = {
  90         {
  91                 .name = "classid",
  92                 .read_u64 = read_classid,
  93                 .write_u64 = write_classid,
  94         },
  95 };
  96
  97 static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
  98 {
  99         return cgroup_add_files(cgrp, ss, ss_files, ARRAY_SIZE(ss_files));
 100 }
 101
 102 struct cls_cgroup_head
 103 {
 104         u32                     handle;
 105         struct tcf_exts         exts;
 106         struct tcf_ematch_tree  ematches;
 107 };
 108
 109 static int cls_cgroup_classify(struct sk_buff *skb, struct tcf_proto *tp,
 110                                struct tcf_result *res)
 111 {
 112         struct cls_cgroup_head *head = tp->root;
 113         u32 classid;
 114
 115         /*
 116          * Due to the nature of the classifier it is required to ignore all
 117          * packets originating from softirq context as accessing `current'
 118          * would lead to false results.
 119          *
 120          * This test assumes that all callers of dev_queue_xmit() explicitely
 121          * disable bh. Knowing this, it is possible to detect softirq based
 122          * calls by looking at the number of nested bh disable calls because
 123          * softirqs always disables bh.
 124          */
 125         if (softirq_count() != SOFTIRQ_OFFSET)
 126                 return -1;
 127
 128         rcu_read_lock();
 129         classid = task_cls_state(current)->classid;
 130         rcu_read_unlock();
 131
 132         if (!classid)
 133                 return -1;
 134
 135         if (!tcf_em_tree_match(skb, &head->ematches, NULL))
 136                 return -1;
 137
 138         res->classid = classid;
 139         res->class = 0;
 140         return tcf_exts_exec(skb, &head->exts, res);
 141 }
 142
 143 static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
 144 {
 145         return 0UL;
 146 }
 147
 148 static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
 149 {
 150 }
 151
 152 static int cls_cgroup_init(struct tcf_proto *tp)
 153 {
 154         return 0;
 155 }
 156
 157 static const struct tcf_ext_map cgroup_ext_map = {
 158         .action = TCA_CGROUP_ACT,
 159         .police = TCA_CGROUP_POLICE,
 160 };
 161
 162 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
 163         [TCA_CGROUP_EMATCHES]   = { .type = NLA_NESTED },
 164 };
 165
 166 static int cls_cgroup_change(struct tcf_proto *tp, unsigned long base,
 167                              u32 handle, struct nlattr **tca,
 168                              unsigned long *arg)
 169 {
 170         struct nlattr *tb[TCA_CGROUP_MAX+1];
 171         struct cls_cgroup_head *head = tp->root;
 172         struct tcf_ematch_tree t;
 173         struct tcf_exts e;
 174         int err;
 175
 176         if (!tca[TCA_OPTIONS])
 177                 return -EINVAL;
 178
 179         if (head == NULL) {
 180                 if (!handle)
 181                         return -EINVAL;
 182
 183                 head = kzalloc(sizeof(*head), GFP_KERNEL);
 184                 if (head == NULL)
 185                         return -ENOBUFS;
 186
 187                 head->handle = handle;
 188
 189                 tcf_tree_lock(tp);
 190                 tp->root = head;
 191                 tcf_tree_unlock(tp);
 192         }
 193
 194         if (handle != head->handle)
 195                 return -ENOENT;
 196
 197         err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
 198                                cgroup_policy);
 199         if (err < 0)
 200                 return err;
 201
 202         err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &cgroup_ext_map);
 203         if (err < 0)
 204                 return err;
 205
 206         err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
 207         if (err < 0)
 208                 return err;
 209
 210         tcf_exts_change(tp, &head->exts, &e);
 211         tcf_em_tree_change(tp, &head->ematches, &t);
 212
 213         return 0;
 214 }
 215
 216 static void cls_cgroup_destroy(struct tcf_proto *tp)
 217 {
 218         struct cls_cgroup_head *head = tp->root;
 219
 220         if (head) {
 221                 tcf_exts_destroy(tp, &head->exts);
 222                 tcf_em_tree_destroy(tp, &head->ematches);
 223                 kfree(head);
 224         }
 225 }
 226
 227 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
 228 {
 229         return -EOPNOTSUPP;
 230 }
 231
 232 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 233 {
 234         struct cls_cgroup_head *head = tp->root;
 235
 236         if (arg->count < arg->skip)
 237                 goto skip;
 238
 239         if (arg->fn(tp, (unsigned long) head, arg) < 0) {
 240                 arg->stop = 1;
 241                 return;
 242         }
 243 skip:
 244         arg->count++;
 245 }
 246
 247 static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
 248                            struct sk_buff *skb, struct tcmsg *t)
 249 {
 250         struct cls_cgroup_head *head = tp->root;
 251         unsigned char *b = skb_tail_pointer(skb);
 252         struct nlattr *nest;
 253
 254         t->tcm_handle = head->handle;
 255
 256         nest = nla_nest_start(skb, TCA_OPTIONS);
 257         if (nest == NULL)
 258                 goto nla_put_failure;
 259
 260         if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
 261             tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
 262                 goto nla_put_failure;
 263
 264         nla_nest_end(skb, nest);
 265
 266         if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
 267                 goto nla_put_failure;
 268
 269         return skb->len;
 270
 271 nla_put_failure:
 272         nlmsg_trim(skb, b);
 273         return -1;
 274 }
 275
 276 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
 277         .kind           =       "cgroup",
 278         .init           =       cls_cgroup_init,
 279         .change         =       cls_cgroup_change,
 280         .classify       =       cls_cgroup_classify,
 281         .destroy        =       cls_cgroup_destroy,
 282         .get            =       cls_cgroup_get,
 283         .put            =       cls_cgroup_put,
 284         .delete         =       cls_cgroup_delete,
 285         .walk           =       cls_cgroup_walk,
 286         .dump           =       cls_cgroup_dump,
 287         .owner          =       THIS_MODULE,
 288 };
 289
 290 static int __init init_cgroup_cls(void)
 291 {
 292         int ret = register_tcf_proto_ops(&cls_cgroup_ops);
 293         if (ret)
 294                 return ret;
 295         ret = cgroup_load_subsys(&net_cls_subsys);
 296         if (ret)
 297                 unregister_tcf_proto_ops(&cls_cgroup_ops);
 298         return ret;
 299 }
 300
 301 static void __exit exit_cgroup_cls(void)
 302 {
 303         unregister_tcf_proto_ops(&cls_cgroup_ops);
 304         cgroup_unload_subsys(&net_cls_subsys);
 305 }
 306
 307 module_init(init_cgroup_cls);
 308 module_exit(exit_cgroup_cls);
 309 MODULE_LICENSE("GPL");