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