LXR linux/kernel/utsname

   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/version.h>
  16#include <linux/sysctl.h>
  17
  18static void *get_uts(ctl_table *table, int write)
  19{
  20        char *which = table->data;
  21        struct uts_namespace *uts_ns;
  22
  23        uts_ns = current->nsproxy->uts_ns;
  24        which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
  25
  26        if (!write)
  27                down_read(&uts_sem);
  28        else
  29                down_write(&uts_sem);
  30        return which;
  31}
  32
  33static void put_uts(ctl_table *table, int write, void *which)
  34{
  35        if (!write)
  36                up_read(&uts_sem);
  37        else
  38                up_write(&uts_sem);
  39}
  40
  41#ifdef CONFIG_PROC_FS
  42/*
  43 *      Special case of dostring for the UTS structure. This has locks
  44 *      to observe. Should this be in kernel/sys.c ????
  45 */
  46static int proc_do_uts_string(ctl_table *table, int write, struct file *filp,
  47                  void __user *buffer, size_t *lenp, loff_t *ppos)
  48{
  49        struct ctl_table uts_table;
  50        int r;
  51        memcpy(&uts_table, table, sizeof(uts_table));
  52        uts_table.data = get_uts(table, write);
  53        r = proc_dostring(&uts_table,write,filp,buffer,lenp, ppos);
  54        put_uts(table, write, uts_table.data);
  55        return r;
  56}
  57#else
  58#define proc_do_uts_string NULL
  59#endif
  60
  61
  62#ifdef CONFIG_SYSCTL_SYSCALL
  63/* The generic string strategy routine: */
  64static int sysctl_uts_string(ctl_table *table, int __user *name, int nlen,
  65                  void __user *oldval, size_t __user *oldlenp,
  66                  void __user *newval, size_t newlen)
  67{
  68        struct ctl_table uts_table;
  69        int r, write;
  70        write = newval && newlen;
  71        memcpy(&uts_table, table, sizeof(uts_table));
  72        uts_table.data = get_uts(table, write);
  73        r = sysctl_string(&uts_table, name, nlen,
  74                oldval, oldlenp, newval, newlen);
  75        put_uts(table, write, uts_table.data);
  76        return r;
  77}
  78#else
  79#define sysctl_uts_string NULL
  80#endif
  81
  82static struct ctl_table uts_kern_table[] = {
  83        {
  84                .ctl_name       = KERN_OSTYPE,
  85                .procname       = "ostype",
  86                .data           = init_uts_ns.name.sysname,
  87                .maxlen         = sizeof(init_uts_ns.name.sysname),
  88                .mode           = 0444,
  89                .proc_handler   = proc_do_uts_string,
  90                .strategy       = sysctl_uts_string,
  91        },
  92        {
  93                .ctl_name       = KERN_OSRELEASE,
  94                .procname       = "osrelease",
  95                .data           = init_uts_ns.name.release,
  96                .maxlen         = sizeof(init_uts_ns.name.release),
  97                .mode           = 0444,
  98                .proc_handler   = proc_do_uts_string,
  99                .strategy       = sysctl_uts_string,
 100        },
 101        {
 102                .ctl_name       = KERN_VERSION,
 103                .procname       = "version",
 104                .data           = init_uts_ns.name.version,
 105                .maxlen         = sizeof(init_uts_ns.name.version),
 106                .mode           = 0444,
 107                .proc_handler   = proc_do_uts_string,
 108                .strategy       = sysctl_uts_string,
 109        },
 110        {
 111                .ctl_name       = KERN_NODENAME,
 112                .procname       = "hostname",
 113                .data           = init_uts_ns.name.nodename,
 114                .maxlen         = sizeof(init_uts_ns.name.nodename),
 115                .mode           = 0644,
 116                .proc_handler   = proc_do_uts_string,
 117                .strategy       = sysctl_uts_string,
 118        },
 119        {
 120                .ctl_name       = KERN_DOMAINNAME,
 121                .procname       = "domainname",
 122                .data           = init_uts_ns.name.domainname,
 123                .maxlen         = sizeof(init_uts_ns.name.domainname),
 124                .mode           = 0644,
 125                .proc_handler   = proc_do_uts_string,
 126                .strategy       = sysctl_uts_string,
 127        },
 128        {}
 129};
 130
 131static struct ctl_table uts_root_table[] = {
 132        {
 133                .ctl_name       = CTL_KERN,
 134                .procname       = "kernel",
 135                .mode           = 0555,
 136                .child          = uts_kern_table,
 137        },
 138        {}
 139};
 140
 141static int __init utsname_sysctl_init(void)
 142{
 143        register_sysctl_table(uts_root_table);
 144        return 0;
 145}
 146
 147__initcall(utsname_sysctl_init);
 148