linux/net/sched/cls_cgroup.c
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   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
  25static 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
  31static 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
  37static 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
  51static void cgrp_destroy(struct cgroup *cgrp)
  52{
  53        kfree(cgrp_cls_state(cgrp));
  54}
  55
  56static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
  57{
  58        return cgrp_cls_state(cgrp)->classid;
  59}
  60
  61static 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
  67static struct cftype ss_files[] = {
  68        {
  69                .name = "classid",
  70                .read_u64 = read_classid,
  71                .write_u64 = write_classid,
  72        },
  73        { }     /* terminate */
  74};
  75
  76struct 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
  87struct cls_cgroup_head {
  88        u32                     handle;
  89        struct tcf_exts         exts;
  90        struct tcf_ematch_tree  ematches;
  91};
  92
  93static 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
 131static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
 132{
 133        return 0UL;
 134}
 135
 136static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
 137{
 138}
 139
 140static int cls_cgroup_init(struct tcf_proto *tp)
 141{
 142        return 0;
 143}
 144
 145static const struct tcf_ext_map cgroup_ext_map = {
 146        .action = TCA_CGROUP_ACT,
 147        .police = TCA_CGROUP_POLICE,
 148};
 149
 150static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
 151        [TCA_CGROUP_EMATCHES]   = { .type = NLA_NESTED },
 152};
 153
 154static 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
 204static 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
 215static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
 216{
 217        return -EOPNOTSUPP;
 218}
 219
 220static 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        }
 231skip:
 232        arg->count++;
 233}
 234
 235static 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
 259nla_put_failure:
 260        nlmsg_trim(skb, b);
 261        return -1;
 262}
 263
 264static 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
 278static 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
 296out:
 297        return ret;
 298}
 299
 300static 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
 312module_init(init_cgroup_cls);
 313module_exit(exit_cgroup_cls);
 314MODULE_LICENSE("GPL");
 315
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