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/slab.h>
  13 #include <linux/cgroup.h>
  14 #include <linux/fdtable.h>
  15 #include <linux/sched/task.h>
  16
  17 #include <net/cls_cgroup.h>
  18 #include <net/sock.h>
  19
  20 static inline struct cgroup_cls_state *css_cls_state(struct cgroup_subsys_state *css)
  21 {
  22         return css ? container_of(css, struct cgroup_cls_state, css) : NULL;
  23 }
  24
  25 struct cgroup_cls_state *task_cls_state(struct task_struct *p)
  26 {
  27         return css_cls_state(task_css_check(p, net_cls_cgrp_id,
  28                                             rcu_read_lock_bh_held()));
  29 }
  30 EXPORT_SYMBOL_GPL(task_cls_state);
  31
  32 static struct cgroup_subsys_state *
  33 cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
  34 {
  35         struct cgroup_cls_state *cs;
  36
  37         cs = kzalloc(sizeof(*cs), GFP_KERNEL);
  38         if (!cs)
  39                 return ERR_PTR(-ENOMEM);
  40
  41         return &cs->css;
  42 }
  43
  44 static int cgrp_css_online(struct cgroup_subsys_state *css)
  45 {
  46         struct cgroup_cls_state *cs = css_cls_state(css);
  47         struct cgroup_cls_state *parent = css_cls_state(css->parent);
  48
  49         if (parent)
  50                 cs->classid = parent->classid;
  51
  52         return 0;
  53 }
  54
  55 static void cgrp_css_free(struct cgroup_subsys_state *css)
  56 {
  57         kfree(css_cls_state(css));
  58 }
  59
  60 static int update_classid_sock(const void *v, struct file *file, unsigned n)
  61 {
  62         int err;
  63         struct socket *sock = sock_from_file(file, &err);
  64
  65         if (sock) {
  66                 spin_lock(&cgroup_sk_update_lock);
  67                 sock_cgroup_set_classid(&sock->sk->sk_cgrp_data,
  68                                         (unsigned long)v);
  69                 spin_unlock(&cgroup_sk_update_lock);
  70         }
  71         return 0;
  72 }
  73
  74 static void cgrp_attach(struct cgroup_taskset *tset)
  75 {
  76         struct cgroup_subsys_state *css;
  77         struct task_struct *p;
  78
  79         cgroup_taskset_for_each(p, css, tset) {
  80                 task_lock(p);
  81                 iterate_fd(p->files, 0, update_classid_sock,
  82                            (void *)(unsigned long)css_cls_state(css)->classid);
  83                 task_unlock(p);
  84         }
  85 }
  86
  87 static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
  88 {
  89         return css_cls_state(css)->classid;
  90 }
  91
  92 static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft,
  93                          u64 value)
  94 {
  95         struct cgroup_cls_state *cs = css_cls_state(css);
  96         struct css_task_iter it;
  97         struct task_struct *p;
  98
  99         cgroup_sk_alloc_disable();
 100
 101         cs->classid = (u32)value;
 102
 103         css_task_iter_start(css, &it);
 104         while ((p = css_task_iter_next(&it))) {
 105                 task_lock(p);
 106                 iterate_fd(p->files, 0, update_classid_sock,
 107                            (void *)(unsigned long)cs->classid);
 108                 task_unlock(p);
 109         }
 110         css_task_iter_end(&it);
 111
 112         return 0;
 113 }
 114
 115 static struct cftype ss_files[] = {
 116         {
 117                 .name           = "classid",
 118                 .read_u64       = read_classid,
 119                 .write_u64      = write_classid,
 120         },
 121         { }     /* terminate */
 122 };
 123
 124 struct cgroup_subsys net_cls_cgrp_subsys = {
 125         .css_alloc              = cgrp_css_alloc,
 126         .css_online             = cgrp_css_online,
 127         .css_free               = cgrp_css_free,
 128         .attach                 = cgrp_attach,
 129         .legacy_cftypes         = ss_files,
 130 };