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_css_alloc(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_css_free(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         .css_alloc      = cgrp_css_alloc,
  79         .css_free       = cgrp_css_free,
  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
  94 struct cls_cgroup_head {
  95         u32                     handle;
  96         struct tcf_exts         exts;
  97         struct tcf_ematch_tree  ematches;
  98 };
  99
 100 static 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
 138 static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
 139 {
 140         return 0UL;
 141 }
 142
 143 static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
 144 {
 145 }
 146
 147 static int cls_cgroup_init(struct tcf_proto *tp)
 148 {
 149         return 0;
 150 }
 151
 152 static const struct tcf_ext_map cgroup_ext_map = {
 153         .action = TCA_CGROUP_ACT,
 154         .police = TCA_CGROUP_POLICE,
 155 };
 156
 157 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
 158         [TCA_CGROUP_EMATCHES]   = { .type = NLA_NESTED },
 159 };
 160
 161 static 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
 212 static 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
 223 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
 224 {
 225         return -EOPNOTSUPP;
 226 }
 227
 228 static 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         }
 239 skip:
 240         arg->count++;
 241 }
 242
 243 static 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
 267 nla_put_failure:
 268         nlmsg_trim(skb, b);
 269         return -1;
 270 }
 271
 272 static 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
 286 static 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
 298 out:
 299         return ret;
 300 }
 301
 302 static 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
 309 module_init(init_cgroup_cls);
 310 module_exit(exit_cgroup_cls);
 311 MODULE_LICENSE("GPL");