net/core/netclassid_cgroup.c

   1 /*
   2  * net/core/netclassid_cgroup.c Classid Cgroupfs Handling
   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/cgroup.h>
  15 #include <linux/fdtable.h>
  16 #include <net/cls_cgroup.h>
  17 #include <net/sock.h>
  18
  19 static inline struct cgroup_cls_state *css_cls_state(struct cgroup_subsys_state *css)
  20 {
  21         return css ? container_of(css, struct cgroup_cls_state, css) : NULL;
  22 }
  23
  24 struct cgroup_cls_state *task_cls_state(struct task_struct *p)
  25 {
  26         return css_cls_state(task_css_check(p, net_cls_cgrp_id,
  27                                             rcu_read_lock_bh_held()));
  28 }
  29 EXPORT_SYMBOL_GPL(task_cls_state);
  30
  31 static struct cgroup_subsys_state *
  32 cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
  33 {
  34         struct cgroup_cls_state *cs;
  35
  36         cs = kzalloc(sizeof(*cs), GFP_KERNEL);
  37         if (!cs)
  38                 return ERR_PTR(-ENOMEM);
  39
  40         return &cs->css;
  41 }
  42
  43 static int cgrp_css_online(struct cgroup_subsys_state *css)
  44 {
  45         struct cgroup_cls_state *cs = css_cls_state(css);
  46         struct cgroup_cls_state *parent = css_cls_state(css->parent);
  47
  48         if (parent)
  49                 cs->classid = parent->classid;
  50
  51         return 0;
  52 }
  53
  54 static void cgrp_css_free(struct cgroup_subsys_state *css)
  55 {
  56         kfree(css_cls_state(css));
  57 }
  58
  59 static int update_classid(const void *v, struct file *file, unsigned n)
  60 {
  61         int err;
  62         struct socket *sock = sock_from_file(file, &err);
  63
  64         if (sock)
  65                 sock->sk->sk_classid = (u32)(unsigned long)v;
  66
  67         return 0;
  68 }
  69
  70 static void cgrp_attach(struct cgroup_subsys_state *css,
  71                         struct cgroup_taskset *tset)
  72 {
  73         struct cgroup_cls_state *cs = css_cls_state(css);
  74         void *v = (void *)(unsigned long)cs->classid;
  75         struct task_struct *p;
  76
  77         cgroup_taskset_for_each(p, tset) {
  78                 task_lock(p);
  79                 iterate_fd(p->files, 0, update_classid, v);
  80                 task_unlock(p);
  81         }
  82 }
  83
  84 static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
  85 {
  86         return css_cls_state(css)->classid;
  87 }
  88
  89 static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft,
  90                          u64 value)
  91 {
  92         css_cls_state(css)->classid = (u32) value;
  93
  94         return 0;
  95 }
  96
  97 static struct cftype ss_files[] = {
  98         {
  99                 .name           = "classid",
 100                 .read_u64       = read_classid,
 101                 .write_u64      = write_classid,
 102         },
 103         { }     /* terminate */
 104 };
 105
 106 struct cgroup_subsys net_cls_cgrp_subsys = {
 107         .css_alloc              = cgrp_css_alloc,
 108         .css_online             = cgrp_css_online,
 109         .css_free               = cgrp_css_free,
 110         .attach                 = cgrp_attach,
 111         .legacy_cftypes         = ss_files,
 112 };