linux/net/sched/cls_cgroup.c
<<
>>
Prefs
   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
  21struct cgroup_cls_state
  22{
  23        struct cgroup_subsys_state css;
  24        u32 classid;
  25};
  26
  27static 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
  33static 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
  39static 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
  53static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
  54{
  55        kfree(cgrp_cls_state(cgrp));
  56}
  57
  58static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
  59{
  60        return cgrp_cls_state(cgrp)->classid;
  61}
  62
  63static 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
  75static struct cftype ss_files[] = {
  76        {
  77                .name = "classid",
  78                .read_u64 = read_classid,
  79                .write_u64 = write_classid,
  80        },
  81};
  82
  83static 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
  88struct 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
  96struct cls_cgroup_head
  97{
  98        u32                     handle;
  99        struct tcf_exts         exts;
 100        struct tcf_ematch_tree  ematches;
 101};
 102
 103static 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
 137static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
 138{
 139        return 0UL;
 140}
 141
 142static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
 143{
 144}
 145
 146static int cls_cgroup_init(struct tcf_proto *tp)
 147{
 148        return 0;
 149}
 150
 151static const struct tcf_ext_map cgroup_ext_map = {
 152        .action = TCA_CGROUP_ACT,
 153        .police = TCA_CGROUP_POLICE,
 154};
 155
 156static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
 157        [TCA_CGROUP_EMATCHES]   = { .type = NLA_NESTED },
 158};
 159
 160static 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
 207static 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
 218static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
 219{
 220        return -EOPNOTSUPP;
 221}
 222
 223static 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        }
 234skip:
 235        arg->count++;
 236}
 237
 238static 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
 262nla_put_failure:
 263        nlmsg_trim(skb, b);
 264        return -1;
 265}
 266
 267static 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
 281static int __init init_cgroup_cls(void)
 282{
 283        return register_tcf_proto_ops(&cls_cgroup_ops);
 284}
 285
 286static void __exit exit_cgroup_cls(void)
 287{
 288        unregister_tcf_proto_ops(&cls_cgroup_ops);
 289}
 290
 291module_init(init_cgroup_cls);
 292module_exit(exit_cgroup_cls);
 293MODULE_LICENSE("GPL");
 294