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f1ecf06854
Adding support for poll() in sysctl fs allows userspace to receive notifications of changes in sysctl entries. This adds a infrastructure to allow files in sysctl fs to be pollable and implements it for hostname and domainname. [akpm@linux-foundation.org: s/declare/define/ for definitions] Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi> Cc: Greg KH <gregkh@suse.de> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
138 lines
3.0 KiB
C
138 lines
3.0 KiB
C
/*
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* Copyright (C) 2007
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*
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* Author: Eric Biederman <ebiederm@xmision.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2 of the
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* License.
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*/
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#include <linux/module.h>
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#include <linux/uts.h>
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#include <linux/utsname.h>
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#include <linux/sysctl.h>
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#include <linux/wait.h>
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static void *get_uts(ctl_table *table, int write)
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{
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char *which = table->data;
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struct uts_namespace *uts_ns;
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uts_ns = current->nsproxy->uts_ns;
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which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
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if (!write)
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down_read(&uts_sem);
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else
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down_write(&uts_sem);
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return which;
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}
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static void put_uts(ctl_table *table, int write, void *which)
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{
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if (!write)
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up_read(&uts_sem);
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else
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up_write(&uts_sem);
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}
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#ifdef CONFIG_PROC_SYSCTL
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/*
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* Special case of dostring for the UTS structure. This has locks
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* to observe. Should this be in kernel/sys.c ????
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*/
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static int proc_do_uts_string(ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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struct ctl_table uts_table;
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int r;
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memcpy(&uts_table, table, sizeof(uts_table));
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uts_table.data = get_uts(table, write);
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r = proc_dostring(&uts_table,write,buffer,lenp, ppos);
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put_uts(table, write, uts_table.data);
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if (write)
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proc_sys_poll_notify(table->poll);
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return r;
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}
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#else
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#define proc_do_uts_string NULL
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#endif
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static DEFINE_CTL_TABLE_POLL(hostname_poll);
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static DEFINE_CTL_TABLE_POLL(domainname_poll);
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static struct ctl_table uts_kern_table[] = {
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{
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.procname = "ostype",
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.data = init_uts_ns.name.sysname,
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.maxlen = sizeof(init_uts_ns.name.sysname),
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.mode = 0444,
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.proc_handler = proc_do_uts_string,
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},
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{
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.procname = "osrelease",
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.data = init_uts_ns.name.release,
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.maxlen = sizeof(init_uts_ns.name.release),
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.mode = 0444,
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.proc_handler = proc_do_uts_string,
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},
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{
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.procname = "version",
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.data = init_uts_ns.name.version,
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.maxlen = sizeof(init_uts_ns.name.version),
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.mode = 0444,
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.proc_handler = proc_do_uts_string,
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},
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{
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.procname = "hostname",
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.data = init_uts_ns.name.nodename,
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.maxlen = sizeof(init_uts_ns.name.nodename),
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.mode = 0644,
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.proc_handler = proc_do_uts_string,
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.poll = &hostname_poll,
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},
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{
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.procname = "domainname",
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.data = init_uts_ns.name.domainname,
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.maxlen = sizeof(init_uts_ns.name.domainname),
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.mode = 0644,
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.proc_handler = proc_do_uts_string,
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.poll = &domainname_poll,
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},
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{}
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};
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static struct ctl_table uts_root_table[] = {
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{
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.procname = "kernel",
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.mode = 0555,
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.child = uts_kern_table,
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},
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{}
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};
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#ifdef CONFIG_PROC_SYSCTL
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/*
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* Notify userspace about a change in a certain entry of uts_kern_table,
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* identified by the parameter proc.
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*/
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void uts_proc_notify(enum uts_proc proc)
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{
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struct ctl_table *table = &uts_kern_table[proc];
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proc_sys_poll_notify(table->poll);
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}
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#endif
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static int __init utsname_sysctl_init(void)
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{
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register_sysctl_table(uts_root_table);
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return 0;
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}
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__initcall(utsname_sysctl_init);
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