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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         struct cgroup_cls_state *cs;
 108         int ret = 0;
 109
 110         /*
 111          * Due to the nature of the classifier it is required to ignore all
 112          * packets originating from softirq context as accessing `current'
 113          * would lead to false results.
 114          *
 115          * This test assumes that all callers of dev_queue_xmit() explicitely
 116          * disable bh. Knowing this, it is possible to detect softirq based
 117          * calls by looking at the number of nested bh disable calls because
 118          * softirqs always disables bh.
 119          */
 120         if (softirq_count() != SOFTIRQ_OFFSET)
 121                 return -1;
 122
 123         rcu_read_lock();
 124         cs = task_cls_state(current);
 125         if (cs->classid && tcf_em_tree_match(skb, &head->ematches, NULL)) {
 126                 res->classid = cs->classid;
 127                 res->class = 0;
 128                 ret = tcf_exts_exec(skb, &head->exts, res);
 129         } else
 130                 ret = -1;
 131
 132         rcu_read_unlock();
 133
 134         return ret;
 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 (head == NULL) {
 171                 if (!handle)
 172                         return -EINVAL;
 173
 174                 head = kzalloc(sizeof(*head), GFP_KERNEL);
 175                 if (head == NULL)
 176                         return -ENOBUFS;
 177
 178                 head->handle = handle;
 179
 180                 tcf_tree_lock(tp);
 181                 tp->root = head;
 182                 tcf_tree_unlock(tp);
 183         }
 184
 185         if (handle != head->handle)
 186                 return -ENOENT;
 187
 188         err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
 189                                cgroup_policy);
 190         if (err < 0)
 191                 return err;
 192
 193         err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &cgroup_ext_map);
 194         if (err < 0)
 195                 return err;
 196
 197         err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
 198         if (err < 0)
 199                 return err;
 200
 201         tcf_exts_change(tp, &head->exts, &e);
 202         tcf_em_tree_change(tp, &head->ematches, &t);
 203
 204         return 0;
 205 }
 206
 207 static void cls_cgroup_destroy(struct tcf_proto *tp)
 208 {
 209         struct cls_cgroup_head *head = tp->root;
 210
 211         if (head) {
 212                 tcf_exts_destroy(tp, &head->exts);
 213                 tcf_em_tree_destroy(tp, &head->ematches);
 214                 kfree(head);
 215         }
 216 }
 217
 218 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
 219 {
 220         return -EOPNOTSUPP;
 221 }
 222
 223 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 224 {
 225         struct cls_cgroup_head *head = tp->root;
 226
 227         if (arg->count < arg->skip)
 228                 goto skip;
 229
 230         if (arg->fn(tp, (unsigned long) head, arg) < 0) {
 231                 arg->stop = 1;
 232                 return;
 233         }
 234 skip:
 235         arg->count++;
 236 }
 237
 238 static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
 239                            struct sk_buff *skb, struct tcmsg *t)
 240 {
 241         struct cls_cgroup_head *head = tp->root;
 242         unsigned char *b = skb_tail_pointer(skb);
 243         struct nlattr *nest;
 244
 245         t->tcm_handle = head->handle;
 246
 247         nest = nla_nest_start(skb, TCA_OPTIONS);
 248         if (nest == NULL)
 249                 goto nla_put_failure;
 250
 251         if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
 252             tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
 253                 goto nla_put_failure;
 254
 255         nla_nest_end(skb, nest);
 256
 257         if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
 258                 goto nla_put_failure;
 259
 260         return skb->len;
 261
 262 nla_put_failure:
 263         nlmsg_trim(skb, b);
 264         return -1;
 265 }
 266
 267 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
 268         .kind           =       "cgroup",
 269         .init           =       cls_cgroup_init,
 270         .change         =       cls_cgroup_change,
 271         .classify       =       cls_cgroup_classify,
 272         .destroy        =       cls_cgroup_destroy,
 273         .get            =       cls_cgroup_get,
 274         .put            =       cls_cgroup_put,
 275         .delete         =       cls_cgroup_delete,
 276         .walk           =       cls_cgroup_walk,
 277         .dump           =       cls_cgroup_dump,
 278         .owner          =       THIS_MODULE,
 279 };
 280
 281 static int __init init_cgroup_cls(void)
 282 {
 283         return register_tcf_proto_ops(&cls_cgroup_ops);
 284 }
 285
 286 static void __exit exit_cgroup_cls(void)
 287 {
 288         unregister_tcf_proto_ops(&cls_cgroup_ops);
 289 }
 290
 291 module_init(init_cgroup_cls);
 292 module_exit(exit_cgroup_cls);
 293 MODULE_LICENSE("GPL");