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/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, int __user *name, int nlen,
  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, name, nlen,
  73                oldval, oldlenp, newval, newlen);
  74        put_uts(table, write, uts_table.data);
  75        return r;
  76}
  77#else
  78#define sysctl_uts_string NULL
  79#endif
  80
  81static struct ctl_table uts_kern_table[] = {
  82        {
  83                .ctl_name       = KERN_OSTYPE,
  84                .procname       = "ostype",
  85                .data           = init_uts_ns.name.sysname,
  86                .maxlen         = sizeof(init_uts_ns.name.sysname),
  87                .mode           = 0444,
  88                .proc_handler   = proc_do_uts_string,
  89                .strategy       = sysctl_uts_string,
  90        },
  91        {
  92                .ctl_name       = KERN_OSRELEASE,
  93                .procname       = "osrelease",
  94                .data           = init_uts_ns.name.release,
  95                .maxlen         = sizeof(init_uts_ns.name.release),
  96                .mode           = 0444,
  97                .proc_handler   = proc_do_uts_string,
  98                .strategy       = sysctl_uts_string,
  99        },
 100        {
 101                .ctl_name       = KERN_VERSION,
 102                .procname       = "version",
 103                .data           = init_uts_ns.name.version,
 104                .maxlen         = sizeof(init_uts_ns.name.version),
 105                .mode           = 0444,
 106                .proc_handler   = proc_do_uts_string,
 107                .strategy       = sysctl_uts_string,
 108        },
 109        {
 110                .ctl_name       = KERN_NODENAME,
 111                .procname       = "hostname",
 112                .data           = init_uts_ns.name.nodename,
 113                .maxlen         = sizeof(init_uts_ns.name.nodename),
 114                .mode           = 0644,
 115                .proc_handler   = proc_do_uts_string,
 116                .strategy       = sysctl_uts_string,
 117        },
 118        {
 119                .ctl_name       = KERN_DOMAINNAME,
 120                .procname       = "domainname",
 121                .data           = init_uts_ns.name.domainname,
 122                .maxlen         = sizeof(init_uts_ns.name.domainname),
 123                .mode           = 0644,
 124                .proc_handler   = proc_do_uts_string,
 125                .strategy       = sysctl_uts_string,
 126        },
 127        {}
 128};
 129
 130static struct ctl_table uts_root_table[] = {
 131        {
 132                .ctl_name       = CTL_KERN,
 133                .procname       = "kernel",
 134                .mode           = 0555,
 135                .child          = uts_kern_table,
 136        },
 137        {}
 138};
 139
 140static int __init utsname_sysctl_init(void)
 141{
 142        register_sysctl_table(uts_root_table);
 143        return 0;
 144}
 145
 146__initcall(utsname_sysctl_init);
 147