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