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