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        .subsys_id      = net_cls_subsys_id,
  81        .base_cftypes   = ss_files,
  82        .module         = THIS_MODULE,
  83
  84        /*
  85         * While net_cls cgroup has the rudimentary hierarchy support of
  86         * inheriting the parent's classid on cgroup creation, it doesn't
  87         * properly propagates config changes in ancestors to their
  88         * descendents.  A child should follow the parent's configuration
  89         * but be allowed to override it.  Fix it and remove the following.
  90         */
  91        .broken_hierarchy = true,
  92};
  93
  94struct cls_cgroup_head {
  95        u32                     handle;
  96        struct tcf_exts         exts;
  97        struct tcf_ematch_tree  ematches;
  98};
  99
 100static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp,
 101                               struct tcf_result *res)
 102{
 103        struct cls_cgroup_head *head = tp->root;
 104        u32 classid;
 105
 106        rcu_read_lock();
 107        classid = task_cls_state(current)->classid;
 108        rcu_read_unlock();
 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 (in_serving_softirq()) {
 121                /* If there is an sk_classid we'll use that. */
 122                if (!skb->sk)
 123                        return -1;
 124                classid = skb->sk->sk_classid;
 125        }
 126
 127        if (!classid)
 128                return -1;
 129
 130        if (!tcf_em_tree_match(skb, &head->ematches, NULL))
 131                return -1;
 132
 133        res->classid = classid;
 134        res->class = 0;
 135        return tcf_exts_exec(skb, &head->exts, res);
 136}
 137
 138static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
 139{
 140        return 0UL;
 141}
 142
 143static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
 144{
 145}
 146
 147static int cls_cgroup_init(struct tcf_proto *tp)
 148{
 149        return 0;
 150}
 151
 152static const struct tcf_ext_map cgroup_ext_map = {
 153        .action = TCA_CGROUP_ACT,
 154        .police = TCA_CGROUP_POLICE,
 155};
 156
 157static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
 158        [TCA_CGROUP_EMATCHES]   = { .type = NLA_NESTED },
 159};
 160
 161static int cls_cgroup_change(struct sk_buff *in_skb,
 162                             struct tcf_proto *tp, unsigned long base,
 163                             u32 handle, struct nlattr **tca,
 164                             unsigned long *arg)
 165{
 166        struct nlattr *tb[TCA_CGROUP_MAX + 1];
 167        struct cls_cgroup_head *head = tp->root;
 168        struct tcf_ematch_tree t;
 169        struct tcf_exts e;
 170        int err;
 171
 172        if (!tca[TCA_OPTIONS])
 173                return -EINVAL;
 174
 175        if (head == NULL) {
 176                if (!handle)
 177                        return -EINVAL;
 178
 179                head = kzalloc(sizeof(*head), GFP_KERNEL);
 180                if (head == NULL)
 181                        return -ENOBUFS;
 182
 183                head->handle = handle;
 184
 185                tcf_tree_lock(tp);
 186                tp->root = head;
 187                tcf_tree_unlock(tp);
 188        }
 189
 190        if (handle != head->handle)
 191                return -ENOENT;
 192
 193        err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
 194                               cgroup_policy);
 195        if (err < 0)
 196                return err;
 197
 198        err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &cgroup_ext_map);
 199        if (err < 0)
 200                return err;
 201
 202        err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
 203        if (err < 0)
 204                return err;
 205
 206        tcf_exts_change(tp, &head->exts, &e);
 207        tcf_em_tree_change(tp, &head->ematches, &t);
 208
 209        return 0;
 210}
 211
 212static void cls_cgroup_destroy(struct tcf_proto *tp)
 213{
 214        struct cls_cgroup_head *head = tp->root;
 215
 216        if (head) {
 217                tcf_exts_destroy(tp, &head->exts);
 218                tcf_em_tree_destroy(tp, &head->ematches);
 219                kfree(head);
 220        }
 221}
 222
 223static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
 224{
 225        return -EOPNOTSUPP;
 226}
 227
 228static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 229{
 230        struct cls_cgroup_head *head = tp->root;
 231
 232        if (arg->count < arg->skip)
 233                goto skip;
 234
 235        if (arg->fn(tp, (unsigned long) head, arg) < 0) {
 236                arg->stop = 1;
 237                return;
 238        }
 239skip:
 240        arg->count++;
 241}
 242
 243static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
 244                           struct sk_buff *skb, struct tcmsg *t)
 245{
 246        struct cls_cgroup_head *head = tp->root;
 247        unsigned char *b = skb_tail_pointer(skb);
 248        struct nlattr *nest;
 249
 250        t->tcm_handle = head->handle;
 251
 252        nest = nla_nest_start(skb, TCA_OPTIONS);
 253        if (nest == NULL)
 254                goto nla_put_failure;
 255
 256        if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
 257            tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
 258                goto nla_put_failure;
 259
 260        nla_nest_end(skb, nest);
 261
 262        if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
 263                goto nla_put_failure;
 264
 265        return skb->len;
 266
 267nla_put_failure:
 268        nlmsg_trim(skb, b);
 269        return -1;
 270}
 271
 272static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
 273        .kind           =       "cgroup",
 274        .init           =       cls_cgroup_init,
 275        .change         =       cls_cgroup_change,
 276        .classify       =       cls_cgroup_classify,
 277        .destroy        =       cls_cgroup_destroy,
 278        .get            =       cls_cgroup_get,
 279        .put            =       cls_cgroup_put,
 280        .delete         =       cls_cgroup_delete,
 281        .walk           =       cls_cgroup_walk,
 282        .dump           =       cls_cgroup_dump,
 283        .owner          =       THIS_MODULE,
 284};
 285
 286static int __init init_cgroup_cls(void)
 287{
 288        int ret;
 289
 290        ret = cgroup_load_subsys(&net_cls_subsys);
 291        if (ret)
 292                goto out;
 293
 294        ret = register_tcf_proto_ops(&cls_cgroup_ops);
 295        if (ret)
 296                cgroup_unload_subsys(&net_cls_subsys);
 297
 298out:
 299        return ret;
 300}
 301
 302static void __exit exit_cgroup_cls(void)
 303{
 304        unregister_tcf_proto_ops(&cls_cgroup_ops);
 305
 306        cgroup_unload_subsys(&net_cls_subsys);
 307}
 308
 309module_init(init_cgroup_cls);
 310module_exit(exit_cgroup_cls);
 311MODULE_LICENSE("GPL");
 312
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