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/types.h>
  15 #include <linux/string.h>
  16 #include <linux/errno.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/cgroup.h>
  19 #include <linux/rcupdate.h>
  20 #include <net/rtnetlink.h>
  21 #include <net/pkt_cls.h>
  22 #include <net/sock.h>
  23 #include <net/cls_cgroup.h>
  24
  25 static struct cgroup_subsys_state *cgrp_create(struct cgroup_subsys *ss,
  26                                                struct cgroup *cgrp);
  27 static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp);
  28 static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp);
  29
  30 struct cgroup_subsys net_cls_subsys = {
  31         .name           = "net_cls",
  32         .create         = cgrp_create,
  33         .destroy        = cgrp_destroy,
  34         .populate       = cgrp_populate,
  35 #ifdef CONFIG_NET_CLS_CGROUP
  36         .subsys_id      = net_cls_subsys_id,
  37 #else
  38 #define net_cls_subsys_id net_cls_subsys.subsys_id
  39 #endif
  40         .module         = THIS_MODULE,
  41 };
  42
  43
  44 static inline struct cgroup_cls_state *cgrp_cls_state(struct cgroup *cgrp)
  45 {
  46         return container_of(cgroup_subsys_state(cgrp, net_cls_subsys_id),
  47                             struct cgroup_cls_state, css);
  48 }
  49
  50 static inline struct cgroup_cls_state *task_cls_state(struct task_struct *p)
  51 {
  52         return container_of(task_subsys_state(p, net_cls_subsys_id),
  53                             struct cgroup_cls_state, css);
  54 }
  55
  56 static struct cgroup_subsys_state *cgrp_create(struct cgroup_subsys *ss,
  57                                                  struct cgroup *cgrp)
  58 {
  59         struct cgroup_cls_state *cs;
  60
  61         if (!(cs = kzalloc(sizeof(*cs), GFP_KERNEL)))
  62                 return ERR_PTR(-ENOMEM);
  63
  64         if (cgrp->parent)
  65                 cs->classid = cgrp_cls_state(cgrp->parent)->classid;
  66
  67         return &cs->css;
  68 }
  69
  70 static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
  71 {
  72         kfree(cgrp_cls_state(cgrp));
  73 }
  74
  75 static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
  76 {
  77         return cgrp_cls_state(cgrp)->classid;
  78 }
  79
  80 static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
  81 {
  82         cgrp_cls_state(cgrp)->classid = (u32) value;
  83         return 0;
  84 }
  85
  86 static struct cftype ss_files[] = {
  87         {
  88                 .name = "classid",
  89                 .read_u64 = read_classid,
  90                 .write_u64 = write_classid,
  91         },
  92 };
  93
  94 static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
  95 {
  96         return cgroup_add_files(cgrp, ss, ss_files, ARRAY_SIZE(ss_files));
  97 }
  98
  99 struct cls_cgroup_head
 100 {
 101         u32                     handle;
 102         struct tcf_exts         exts;
 103         struct tcf_ematch_tree  ematches;
 104 };
 105
 106 static int cls_cgroup_classify(struct sk_buff *skb, struct tcf_proto *tp,
 107                                struct tcf_result *res)
 108 {
 109         struct cls_cgroup_head *head = tp->root;
 110         u32 classid;
 111
 112         rcu_read_lock();
 113         classid = task_cls_state(current)->classid;
 114         rcu_read_unlock();
 115
 116         /*
 117          * Due to the nature of the classifier it is required to ignore all
 118          * packets originating from softirq context as accessing `current'
 119          * would lead to false results.
 120          *
 121          * This test assumes that all callers of dev_queue_xmit() explicitely
 122          * disable bh. Knowing this, it is possible to detect softirq based
 123          * calls by looking at the number of nested bh disable calls because
 124          * softirqs always disables bh.
 125          */
 126         if (softirq_count() != SOFTIRQ_OFFSET) {
 127                 /* If there is an sk_classid we'll use that. */
 128                 if (!skb->sk)
 129                         return -1;
 130                 classid = skb->sk->sk_classid;
 131         }
 132
 133         if (!classid)
 134                 return -1;
 135
 136         if (!tcf_em_tree_match(skb, &head->ematches, NULL))
 137                 return -1;
 138
 139         res->classid = classid;
 140         res->class = 0;
 141         return tcf_exts_exec(skb, &head->exts, res);
 142 }
 143
 144 static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
 145 {
 146         return 0UL;
 147 }
 148
 149 static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
 150 {
 151 }
 152
 153 static int cls_cgroup_init(struct tcf_proto *tp)
 154 {
 155         return 0;
 156 }
 157
 158 static const struct tcf_ext_map cgroup_ext_map = {
 159         .action = TCA_CGROUP_ACT,
 160         .police = TCA_CGROUP_POLICE,
 161 };
 162
 163 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
 164         [TCA_CGROUP_EMATCHES]   = { .type = NLA_NESTED },
 165 };
 166
 167 static int cls_cgroup_change(struct tcf_proto *tp, unsigned long base,
 168                              u32 handle, struct nlattr **tca,
 169                              unsigned long *arg)
 170 {
 171         struct nlattr *tb[TCA_CGROUP_MAX+1];
 172         struct cls_cgroup_head *head = tp->root;
 173         struct tcf_ematch_tree t;
 174         struct tcf_exts e;
 175         int err;
 176
 177         if (!tca[TCA_OPTIONS])
 178                 return -EINVAL;
 179
 180         if (head == NULL) {
 181                 if (!handle)
 182                         return -EINVAL;
 183
 184                 head = kzalloc(sizeof(*head), GFP_KERNEL);
 185                 if (head == NULL)
 186                         return -ENOBUFS;
 187
 188                 head->handle = handle;
 189
 190                 tcf_tree_lock(tp);
 191                 tp->root = head;
 192                 tcf_tree_unlock(tp);
 193         }
 194
 195         if (handle != head->handle)
 196                 return -ENOENT;
 197
 198         err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
 199                                cgroup_policy);
 200         if (err < 0)
 201                 return err;
 202
 203         err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &cgroup_ext_map);
 204         if (err < 0)
 205                 return err;
 206
 207         err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
 208         if (err < 0)
 209                 return err;
 210
 211         tcf_exts_change(tp, &head->exts, &e);
 212         tcf_em_tree_change(tp, &head->ematches, &t);
 213
 214         return 0;
 215 }
 216
 217 static void cls_cgroup_destroy(struct tcf_proto *tp)
 218 {
 219         struct cls_cgroup_head *head = tp->root;
 220
 221         if (head) {
 222                 tcf_exts_destroy(tp, &head->exts);
 223                 tcf_em_tree_destroy(tp, &head->ematches);
 224                 kfree(head);
 225         }
 226 }
 227
 228 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
 229 {
 230         return -EOPNOTSUPP;
 231 }
 232
 233 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 234 {
 235         struct cls_cgroup_head *head = tp->root;
 236
 237         if (arg->count < arg->skip)
 238                 goto skip;
 239
 240         if (arg->fn(tp, (unsigned long) head, arg) < 0) {
 241                 arg->stop = 1;
 242                 return;
 243         }
 244 skip:
 245         arg->count++;
 246 }
 247
 248 static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
 249                            struct sk_buff *skb, struct tcmsg *t)
 250 {
 251         struct cls_cgroup_head *head = tp->root;
 252         unsigned char *b = skb_tail_pointer(skb);
 253         struct nlattr *nest;
 254
 255         t->tcm_handle = head->handle;
 256
 257         nest = nla_nest_start(skb, TCA_OPTIONS);
 258         if (nest == NULL)
 259                 goto nla_put_failure;
 260
 261         if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
 262             tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
 263                 goto nla_put_failure;
 264
 265         nla_nest_end(skb, nest);
 266
 267         if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
 268                 goto nla_put_failure;
 269
 270         return skb->len;
 271
 272 nla_put_failure:
 273         nlmsg_trim(skb, b);
 274         return -1;
 275 }
 276
 277 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
 278         .kind           =       "cgroup",
 279         .init           =       cls_cgroup_init,
 280         .change         =       cls_cgroup_change,
 281         .classify       =       cls_cgroup_classify,
 282         .destroy        =       cls_cgroup_destroy,
 283         .get            =       cls_cgroup_get,
 284         .put            =       cls_cgroup_put,
 285         .delete         =       cls_cgroup_delete,
 286         .walk           =       cls_cgroup_walk,
 287         .dump           =       cls_cgroup_dump,
 288         .owner          =       THIS_MODULE,
 289 };
 290
 291 static int __init init_cgroup_cls(void)
 292 {
 293         int ret;
 294
 295         ret = cgroup_load_subsys(&net_cls_subsys);
 296         if (ret)
 297                 goto out;
 298
 299 #ifndef CONFIG_NET_CLS_CGROUP
 300         /* We can't use rcu_assign_pointer because this is an int. */
 301         smp_wmb();
 302         net_cls_subsys_id = net_cls_subsys.subsys_id;
 303 #endif
 304
 305         ret = register_tcf_proto_ops(&cls_cgroup_ops);
 306         if (ret)
 307                 cgroup_unload_subsys(&net_cls_subsys);
 308
 309 out:
 310         return ret;
 311 }
 312
 313 static void __exit exit_cgroup_cls(void)
 314 {
 315         unregister_tcf_proto_ops(&cls_cgroup_ops);
 316
 317 #ifndef CONFIG_NET_CLS_CGROUP
 318         net_cls_subsys_id = -1;
 319         synchronize_rcu();
 320 #endif
 321
 322         cgroup_unload_subsys(&net_cls_subsys);
 323 }
 324
 325 module_init(init_cgroup_cls);
 326 module_exit(exit_cgroup_cls);
 327 MODULE_LICENSE("GPL");