linux/kernel/utsname_sysctl.c
<<
>>
Prefs
   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_FS
  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, struct file *filp,
  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,filp,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
  60
  61#ifdef CONFIG_SYSCTL_SYSCALL
  62/* The generic string strategy routine: */
  63static int sysctl_uts_string(ctl_table *table,
  64                  void __user *oldval, size_t __user *oldlenp,
  65                  void __user *newval, size_t newlen)
  66{
  67        struct ctl_table uts_table;
  68        int r, write;
  69        write = newval && newlen;
  70        memcpy(&uts_table, table, sizeof(uts_table));
  71        uts_table.data = get_uts(table, write);
  72        r = sysctl_string(&uts_table, oldval, oldlenp, newval, newlen);
  73        put_uts(table, write, uts_table.data);
  74        return r;
  75}
  76#else
  77#define sysctl_uts_string NULL
  78#endif
  79
  80static struct ctl_table uts_kern_table[] = {
  81        {
  82                .ctl_name       = KERN_OSTYPE,
  83                .procname       = "ostype",
  84                .data           = init_uts_ns.name.sysname,
  85                .maxlen         = sizeof(init_uts_ns.name.sysname),
  86                .mode           = 0444,
  87                .proc_handler   = proc_do_uts_string,
  88                .strategy       = sysctl_uts_string,
  89        },
  90        {
  91                .ctl_name       = KERN_OSRELEASE,
  92                .procname       = "osrelease",
  93                .data           = init_uts_ns.name.release,
  94                .maxlen         = sizeof(init_uts_ns.name.release),
  95                .mode           = 0444,
  96                .proc_handler   = proc_do_uts_string,
  97                .strategy       = sysctl_uts_string,
  98        },
  99        {
 100                .ctl_name       = KERN_VERSION,
 101                .procname       = "version",
 102                .data           = init_uts_ns.name.version,
 103                .maxlen         = sizeof(init_uts_ns.name.version),
 104                .mode           = 0444,
 105                .proc_handler   = proc_do_uts_string,
 106                .strategy       = sysctl_uts_string,
 107        },
 108        {
 109                .ctl_name       = KERN_NODENAME,
 110                .procname       = "hostname",
 111                .data           = init_uts_ns.name.nodename,
 112                .maxlen         = sizeof(init_uts_ns.name.nodename),
 113                .mode           = 0644,
 114                .proc_handler   = proc_do_uts_string,
 115                .strategy       = sysctl_uts_string,
 116        },
 117        {
 118                .ctl_name       = KERN_DOMAINNAME,
 119                .procname       = "domainname",
 120                .data           = init_uts_ns.name.domainname,
 121                .maxlen         = sizeof(init_uts_ns.name.domainname),
 122                .mode           = 0644,
 123                .proc_handler   = proc_do_uts_string,
 124                .strategy       = sysctl_uts_string,
 125        },
 126        {}
 127};
 128
 129static struct ctl_table uts_root_table[] = {
 130        {
 131                .ctl_name       = CTL_KERN,
 132                .procname       = "kernel",
 133                .mode           = 0555,
 134                .child          = uts_kern_table,
 135        },
 136        {}
 137};
 138
 139static int __init utsname_sysctl_init(void)
 140{
 141        register_sysctl_table(uts_root_table);
 142        return 0;
 143}
 144
 145__initcall(utsname_sysctl_init);
 146