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