net/core/netclassid_cgroup.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * net/core/netclassid_cgroup.c Classid Cgroupfs Handling
   4  *
   5  * Authors:     Thomas Graf <tgraf@suug.ch>
   6  */
   7
   8 #include <linux/slab.h>
   9 #include <linux/cgroup.h>
  10 #include <linux/fdtable.h>
  11 #include <linux/sched/task.h>
  12
  13 #include <net/cls_cgroup.h>
  14 #include <net/sock.h>
  15
  16 static inline struct cgroup_cls_state *css_cls_state(struct cgroup_subsys_state *css)
  17 {
  18         return css ? container_of(css, struct cgroup_cls_state, css) : NULL;
  19 }
  20
  21 struct cgroup_cls_state *task_cls_state(struct task_struct *p)
  22 {
  23         return css_cls_state(task_css_check(p, net_cls_cgrp_id,
  24                                             rcu_read_lock_bh_held()));
  25 }
  26 EXPORT_SYMBOL_GPL(task_cls_state);
  27
  28 static struct cgroup_subsys_state *
  29 cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
  30 {
  31         struct cgroup_cls_state *cs;
  32
  33         cs = kzalloc(sizeof(*cs), GFP_KERNEL);
  34         if (!cs)
  35                 return ERR_PTR(-ENOMEM);
  36
  37         return &cs->css;
  38 }
  39
  40 static int cgrp_css_online(struct cgroup_subsys_state *css)
  41 {
  42         struct cgroup_cls_state *cs = css_cls_state(css);
  43         struct cgroup_cls_state *parent = css_cls_state(css->parent);
  44
  45         if (parent)
  46                 cs->classid = parent->classid;
  47
  48         return 0;
  49 }
  50
  51 static void cgrp_css_free(struct cgroup_subsys_state *css)
  52 {
  53         kfree(css_cls_state(css));
  54 }
  55
  56 static int update_classid_sock(const void *v, struct file *file, unsigned n)
  57 {
  58         int err;
  59         struct socket *sock = sock_from_file(file, &err);
  60
  61         if (sock) {
  62                 spin_lock(&cgroup_sk_update_lock);
  63                 sock_cgroup_set_classid(&sock->sk->sk_cgrp_data,
  64                                         (unsigned long)v);
  65                 spin_unlock(&cgroup_sk_update_lock);
  66         }
  67         return 0;
  68 }
  69
  70 static void cgrp_attach(struct cgroup_taskset *tset)
  71 {
  72         struct cgroup_subsys_state *css;
  73         struct task_struct *p;
  74
  75         cgroup_taskset_for_each(p, css, tset) {
  76                 task_lock(p);
  77                 iterate_fd(p->files, 0, update_classid_sock,
  78                            (void *)(unsigned long)css_cls_state(css)->classid);
  79                 task_unlock(p);
  80         }
  81 }
  82
  83 static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
  84 {
  85         return css_cls_state(css)->classid;
  86 }
  87
  88 static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft,
  89                          u64 value)
  90 {
  91         struct cgroup_cls_state *cs = css_cls_state(css);
  92         struct css_task_iter it;
  93         struct task_struct *p;
  94
  95         cgroup_sk_alloc_disable();
  96
  97         cs->classid = (u32)value;
  98
  99         css_task_iter_start(css, 0, &it);
 100         while ((p = css_task_iter_next(&it))) {
 101                 task_lock(p);
 102                 iterate_fd(p->files, 0, update_classid_sock,
 103                            (void *)(unsigned long)cs->classid);
 104                 task_unlock(p);
 105                 cond_resched();
 106         }
 107         css_task_iter_end(&it);
 108
 109         return 0;
 110 }
 111
 112 static struct cftype ss_files[] = {
 113         {
 114                 .name           = "classid",
 115                 .read_u64       = read_classid,
 116                 .write_u64      = write_classid,
 117         },
 118         { }     /* terminate */
 119 };
 120
 121 struct cgroup_subsys net_cls_cgrp_subsys = {
 122         .css_alloc              = cgrp_css_alloc,
 123         .css_online             = cgrp_css_online,
 124         .css_free               = cgrp_css_free,
 125         .attach                 = cgrp_attach,
 126         .legacy_cftypes         = ss_files,
 127 };