linux/kernel/utsname_sysctl.c
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   1/*
   2 *  Copyright (C) 2007
   3 *
   4 *  Author: Eric Biederman <ebiederm@xmision.com>
   5 *
   6 *  This program is free software; you can redistribute it and/or
   7 *  modify it under the terms of the GNU General Public License as
   8 *  published by the Free Software Foundation, version 2 of the
   9 *  License.
  10 */
  11
  12#include <linux/module.h>
  13#include <linux/uts.h>
  14#include <linux/utsname.h>
  15#include <linux/sysctl.h>
  16
  17static void *get_uts(ctl_table *table, int write)
  18{
  19        char *which = table->data;
  20        struct uts_namespace *uts_ns;
  21
  22        uts_ns = current->nsproxy->uts_ns;
  23        which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
  24
  25        if (!write)
  26                down_read(&uts_sem);
  27        else
  28                down_write(&uts_sem);
  29        return which;
  30}
  31
  32static void put_uts(ctl_table *table, int write, void *which)
  33{
  34        if (!write)
  35                up_read(&uts_sem);
  36        else
  37                up_write(&uts_sem);
  38}
  39
  40#ifdef CONFIG_PROC_SYSCTL
  41/*
  42 *      Special case of dostring for the UTS structure. This has locks
  43 *      to observe. Should this be in kernel/sys.c ????
  44 */
  45static int proc_do_uts_string(ctl_table *table, int write,
  46                  void __user *buffer, size_t *lenp, loff_t *ppos)
  47{
  48        struct ctl_table uts_table;
  49        int r;
  50        memcpy(&uts_table, table, sizeof(uts_table));
  51        uts_table.data = get_uts(table, write);
  52        r = proc_dostring(&uts_table,write,buffer,lenp, ppos);
  53        put_uts(table, write, uts_table.data);
  54        return r;
  55}
  56#else
  57#define proc_do_uts_string NULL
  58#endif
  59
  60static struct ctl_table uts_kern_table[] = {
  61        {
  62                .procname       = "ostype",
  63                .data           = init_uts_ns.name.sysname,
  64                .maxlen         = sizeof(init_uts_ns.name.sysname),
  65                .mode           = 0444,
  66                .proc_handler   = proc_do_uts_string,
  67        },
  68        {
  69                .procname       = "osrelease",
  70                .data           = init_uts_ns.name.release,
  71                .maxlen         = sizeof(init_uts_ns.name.release),
  72                .mode           = 0444,
  73                .proc_handler   = proc_do_uts_string,
  74        },
  75        {
  76                .procname       = "version",
  77                .data           = init_uts_ns.name.version,
  78                .maxlen         = sizeof(init_uts_ns.name.version),
  79                .mode           = 0444,
  80                .proc_handler   = proc_do_uts_string,
  81        },
  82        {
  83                .procname       = "hostname",
  84                .data           = init_uts_ns.name.nodename,
  85                .maxlen         = sizeof(init_uts_ns.name.nodename),
  86                .mode           = 0644,
  87                .proc_handler   = proc_do_uts_string,
  88        },
  89        {
  90                .procname       = "domainname",
  91                .data           = init_uts_ns.name.domainname,
  92                .maxlen         = sizeof(init_uts_ns.name.domainname),
  93                .mode           = 0644,
  94                .proc_handler   = proc_do_uts_string,
  95        },
  96        {}
  97};
  98
  99static struct ctl_table uts_root_table[] = {
 100        {
 101                .procname       = "kernel",
 102                .mode           = 0555,
 103                .child          = uts_kern_table,
 104        },
 105        {}
 106};
 107
 108static int __init utsname_sysctl_init(void)
 109{
 110        register_sysctl_table(uts_root_table);
 111        return 0;
 112}
 113
 114__initcall(utsname_sysctl_init);
 115
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