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/export.h>
  13#include <linux/uts.h>
  14#include <linux/utsname.h>
  15#include <linux/sysctl.h>
  16#include <linux/wait.h>
  17#include <linux/rwsem.h>
  18
  19#ifdef CONFIG_PROC_SYSCTL
  20
  21static void *get_uts(struct ctl_table *table, int write)
  22{
  23        char *which = table->data;
  24        struct uts_namespace *uts_ns;
  25
  26        uts_ns = current->nsproxy->uts_ns;
  27        which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
  28
  29        if (!write)
  30                down_read(&uts_sem);
  31        else
  32                down_write(&uts_sem);
  33        return which;
  34}
  35
  36static void put_uts(struct ctl_table *table, int write, void *which)
  37{
  38        if (!write)
  39                up_read(&uts_sem);
  40        else
  41                up_write(&uts_sem);
  42}
  43
  44/*
  45 *      Special case of dostring for the UTS structure. This has locks
  46 *      to observe. Should this be in kernel/sys.c ????
  47 */
  48static int proc_do_uts_string(struct ctl_table *table, int write,
  49                  void __user *buffer, size_t *lenp, loff_t *ppos)
  50{
  51        struct ctl_table uts_table;
  52        int r;
  53        memcpy(&uts_table, table, sizeof(uts_table));
  54        uts_table.data = get_uts(table, write);
  55        r = proc_dostring(&uts_table, write, buffer, lenp, ppos);
  56        put_uts(table, write, uts_table.data);
  57
  58        if (write)
  59                proc_sys_poll_notify(table->poll);
  60
  61        return r;
  62}
  63#else
  64#define proc_do_uts_string NULL
  65#endif
  66
  67static DEFINE_CTL_TABLE_POLL(hostname_poll);
  68static DEFINE_CTL_TABLE_POLL(domainname_poll);
  69
  70static struct ctl_table uts_kern_table[] = {
  71        {
  72                .procname       = "ostype",
  73                .data           = init_uts_ns.name.sysname,
  74                .maxlen         = sizeof(init_uts_ns.name.sysname),
  75                .mode           = 0444,
  76                .proc_handler   = proc_do_uts_string,
  77        },
  78        {
  79                .procname       = "osrelease",
  80                .data           = init_uts_ns.name.release,
  81                .maxlen         = sizeof(init_uts_ns.name.release),
  82                .mode           = 0444,
  83                .proc_handler   = proc_do_uts_string,
  84        },
  85        {
  86                .procname       = "version",
  87                .data           = init_uts_ns.name.version,
  88                .maxlen         = sizeof(init_uts_ns.name.version),
  89                .mode           = 0444,
  90                .proc_handler   = proc_do_uts_string,
  91        },
  92        {
  93                .procname       = "hostname",
  94                .data           = init_uts_ns.name.nodename,
  95                .maxlen         = sizeof(init_uts_ns.name.nodename),
  96                .mode           = 0644,
  97                .proc_handler   = proc_do_uts_string,
  98                .poll           = &hostname_poll,
  99        },
 100        {
 101                .procname       = "domainname",
 102                .data           = init_uts_ns.name.domainname,
 103                .maxlen         = sizeof(init_uts_ns.name.domainname),
 104                .mode           = 0644,
 105                .proc_handler   = proc_do_uts_string,
 106                .poll           = &domainname_poll,
 107        },
 108        {}
 109};
 110
 111static struct ctl_table uts_root_table[] = {
 112        {
 113                .procname       = "kernel",
 114                .mode           = 0555,
 115                .child          = uts_kern_table,
 116        },
 117        {}
 118};
 119
 120#ifdef CONFIG_PROC_SYSCTL
 121/*
 122 * Notify userspace about a change in a certain entry of uts_kern_table,
 123 * identified by the parameter proc.
 124 */
 125void uts_proc_notify(enum uts_proc proc)
 126{
 127        struct ctl_table *table = &uts_kern_table[proc];
 128
 129        proc_sys_poll_notify(table->poll);
 130}
 131#endif
 132
 133static int __init utsname_sysctl_init(void)
 134{
 135        register_sysctl_table(uts_root_table);
 136        return 0;
 137}
 138
 139device_initcall(utsname_sysctl_init);
 140