blob: 0d48ea911508d34566714ec5419796fda9d19178 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Tejun Heo6d66f5c2007-09-20 17:31:38 +09002 * fs/sysfs/symlink.c - sysfs symlink implementation
3 *
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
7 *
8 * This file is released under the GPLv2.
9 *
10 * Please see Documentation/filesystems/sysfs.txt for more information.
Linus Torvalds1da177e2005-04-16 15:20:36 -070011 */
12
13#include <linux/fs.h>
14#include <linux/module.h>
15#include <linux/kobject.h>
Dave Young869512a2007-07-26 14:53:53 +000016#include <linux/mutex.h>
David P. Quigleyddd29ec2009-09-09 14:25:37 -040017#include <linux/security.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018
19#include "sysfs.h"
20
Tejun Heo324a56e2013-12-11 14:11:53 -050021static int sysfs_do_create_link_sd(struct kernfs_node *parent,
22 struct kobject *target_kobj,
Rafael J. Wysocki0bb8f3d2013-01-25 21:51:13 +010023 const char *name, int warn)
Linus Torvalds1da177e2005-04-16 15:20:36 -070024{
Tejun Heo324a56e2013-12-11 14:11:53 -050025 struct kernfs_node *kn, *target = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -070026
Tejun Heo324a56e2013-12-11 14:11:53 -050027 BUG_ON(!name || !parent);
Tejun Heo2b29ac22007-06-14 03:45:15 +090028
Tejun Heo0cae60f2013-10-30 10:28:36 -040029 /*
Tejun Heo324a56e2013-12-11 14:11:53 -050030 * We don't own @target_kobj and it may be removed at any time.
Tejun Heo0cae60f2013-10-30 10:28:36 -040031 * Synchronize using sysfs_symlink_target_lock. See
32 * sysfs_remove_dir() for details.
Tejun Heo2b29ac22007-06-14 03:45:15 +090033 */
Tejun Heo0cae60f2013-10-30 10:28:36 -040034 spin_lock(&sysfs_symlink_target_lock);
Tejun Heo324a56e2013-12-11 14:11:53 -050035 if (target_kobj->sd) {
36 target = target_kobj->sd;
37 kernfs_get(target);
Tejun Heoccf73cf2013-11-28 14:54:30 -050038 }
Tejun Heo0cae60f2013-10-30 10:28:36 -040039 spin_unlock(&sysfs_symlink_target_lock);
Tejun Heo2b29ac22007-06-14 03:45:15 +090040
Tejun Heo324a56e2013-12-11 14:11:53 -050041 if (!target)
Tejun Heo5d0e26b2013-11-23 17:21:50 -050042 return -ENOENT;
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
Tejun Heo324a56e2013-12-11 14:11:53 -050044 kn = kernfs_create_link(parent, name, target);
45 kernfs_put(target);
Tejun Heo5d0e26b2013-11-23 17:21:50 -050046
Tejun Heo324a56e2013-12-11 14:11:53 -050047 if (!IS_ERR(kn))
Tejun Heo5d0e26b2013-11-23 17:21:50 -050048 return 0;
49
Tejun Heo324a56e2013-12-11 14:11:53 -050050 if (warn && PTR_ERR(kn) == -EEXIST)
51 sysfs_warn_dup(parent, name);
52 return PTR_ERR(kn);
Linus Torvalds1da177e2005-04-16 15:20:36 -070053}
54
Linus Torvalds1da177e2005-04-16 15:20:36 -070055/**
Rafael J. Wysocki0bb8f3d2013-01-25 21:51:13 +010056 * sysfs_create_link_sd - create symlink to a given object.
Tejun Heo324a56e2013-12-11 14:11:53 -050057 * @kn: directory we're creating the link in.
Rafael J. Wysocki0bb8f3d2013-01-25 21:51:13 +010058 * @target: object we're pointing to.
59 * @name: name of the symlink.
60 */
Tejun Heo324a56e2013-12-11 14:11:53 -050061int sysfs_create_link_sd(struct kernfs_node *kn, struct kobject *target,
Rafael J. Wysocki0bb8f3d2013-01-25 21:51:13 +010062 const char *name)
63{
Tejun Heo324a56e2013-12-11 14:11:53 -050064 return sysfs_do_create_link_sd(kn, target, name, 1);
Rafael J. Wysocki0bb8f3d2013-01-25 21:51:13 +010065}
66
67static int sysfs_do_create_link(struct kobject *kobj, struct kobject *target,
68 const char *name, int warn)
69{
Tejun Heo324a56e2013-12-11 14:11:53 -050070 struct kernfs_node *parent = NULL;
Rafael J. Wysocki0bb8f3d2013-01-25 21:51:13 +010071
72 if (!kobj)
Tejun Heo324a56e2013-12-11 14:11:53 -050073 parent = sysfs_root_kn;
Rafael J. Wysocki0bb8f3d2013-01-25 21:51:13 +010074 else
Tejun Heo324a56e2013-12-11 14:11:53 -050075 parent = kobj->sd;
Rafael J. Wysocki0bb8f3d2013-01-25 21:51:13 +010076
Tejun Heo324a56e2013-12-11 14:11:53 -050077 if (!parent)
Rafael J. Wysocki0bb8f3d2013-01-25 21:51:13 +010078 return -EFAULT;
79
Tejun Heo324a56e2013-12-11 14:11:53 -050080 return sysfs_do_create_link_sd(parent, target, name, warn);
Rafael J. Wysocki0bb8f3d2013-01-25 21:51:13 +010081}
82
83/**
Cornelia Huck36ce6da2008-06-10 11:09:08 +020084 * sysfs_create_link - create symlink between two objects.
85 * @kobj: object whose directory we're creating the link in.
86 * @target: object we're pointing to.
87 * @name: name of the symlink.
88 */
89int sysfs_create_link(struct kobject *kobj, struct kobject *target,
90 const char *name)
91{
92 return sysfs_do_create_link(kobj, target, name, 1);
93}
Greg Kroah-Hartman1b866752013-08-21 16:17:47 -070094EXPORT_SYMBOL_GPL(sysfs_create_link);
Cornelia Huck36ce6da2008-06-10 11:09:08 +020095
96/**
97 * sysfs_create_link_nowarn - create symlink between two objects.
98 * @kobj: object whose directory we're creating the link in.
99 * @target: object we're pointing to.
100 * @name: name of the symlink.
101 *
Robert P. J. Day6f1cbd42012-09-04 07:23:35 -0400102 * This function does the same as sysfs_create_link(), but it
Cornelia Huck36ce6da2008-06-10 11:09:08 +0200103 * doesn't warn if the link already exists.
104 */
105int sysfs_create_link_nowarn(struct kobject *kobj, struct kobject *target,
106 const char *name)
107{
108 return sysfs_do_create_link(kobj, target, name, 0);
109}
110
111/**
Eric W. Biederman746edb72010-03-30 11:31:28 -0700112 * sysfs_delete_link - remove symlink in object's directory.
113 * @kobj: object we're acting for.
114 * @targ: object we're pointing to.
115 * @name: name of the symlink to remove.
116 *
117 * Unlike sysfs_remove_link sysfs_delete_link has enough information
118 * to successfully delete symlinks in tagged directories.
119 */
120void sysfs_delete_link(struct kobject *kobj, struct kobject *targ,
121 const char *name)
122{
123 const void *ns = NULL;
Tejun Heo0cae60f2013-10-30 10:28:36 -0400124
125 /*
126 * We don't own @target and it may be removed at any time.
127 * Synchronize using sysfs_symlink_target_lock. See
128 * sysfs_remove_dir() for details.
129 */
130 spin_lock(&sysfs_symlink_target_lock);
Tejun Heoac9bba02013-11-29 17:19:09 -0500131 if (targ->sd && kernfs_ns_enabled(kobj->sd))
Tejun Heoadc5e8b2013-12-11 14:11:54 -0500132 ns = targ->sd->ns;
Tejun Heo0cae60f2013-10-30 10:28:36 -0400133 spin_unlock(&sysfs_symlink_target_lock);
Tejun Heo879f40d2013-11-23 17:21:49 -0500134 kernfs_remove_by_name_ns(kobj->sd, name, ns);
Eric W. Biederman746edb72010-03-30 11:31:28 -0700135}
136
137/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138 * sysfs_remove_link - remove symlink in object's directory.
139 * @kobj: object we're acting for.
140 * @name: name of the symlink to remove.
141 */
Greg Kroah-Hartman1b18dc22013-08-21 16:28:26 -0700142void sysfs_remove_link(struct kobject *kobj, const char *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143{
Tejun Heo324a56e2013-12-11 14:11:53 -0500144 struct kernfs_node *parent = NULL;
Mark Fasheha839c5a2008-01-29 14:35:18 -0800145
146 if (!kobj)
Tejun Heo324a56e2013-12-11 14:11:53 -0500147 parent = sysfs_root_kn;
Mark Fasheha839c5a2008-01-29 14:35:18 -0800148 else
Tejun Heo324a56e2013-12-11 14:11:53 -0500149 parent = kobj->sd;
Mark Fasheha839c5a2008-01-29 14:35:18 -0800150
Tejun Heo324a56e2013-12-11 14:11:53 -0500151 kernfs_remove_by_name(parent, name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152}
Greg Kroah-Hartman1b866752013-08-21 16:17:47 -0700153EXPORT_SYMBOL_GPL(sysfs_remove_link);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154
Eric W. Biederman7cb32942010-02-12 19:22:25 -0800155/**
Tejun Heo4b30ee52013-09-11 22:29:06 -0400156 * sysfs_rename_link_ns - rename symlink in object's directory.
Eric W. Biederman7cb32942010-02-12 19:22:25 -0800157 * @kobj: object we're acting for.
158 * @targ: object we're pointing to.
159 * @old: previous name of the symlink.
160 * @new: new name of the symlink.
Tejun Heo4b30ee52013-09-11 22:29:06 -0400161 * @new_ns: new namespace of the symlink.
Eric W. Biederman7cb32942010-02-12 19:22:25 -0800162 *
163 * A helper function for the common rename symlink idiom.
164 */
Tejun Heo4b30ee52013-09-11 22:29:06 -0400165int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
166 const char *old, const char *new, const void *new_ns)
Eric W. Biederman7cb32942010-02-12 19:22:25 -0800167{
Tejun Heo324a56e2013-12-11 14:11:53 -0500168 struct kernfs_node *parent, *kn = NULL;
Tejun Heo4b30ee52013-09-11 22:29:06 -0400169 const void *old_ns = NULL;
Eric W. Biederman7cb32942010-02-12 19:22:25 -0800170 int result;
171
172 if (!kobj)
Tejun Heo324a56e2013-12-11 14:11:53 -0500173 parent = sysfs_root_kn;
Eric W. Biederman7cb32942010-02-12 19:22:25 -0800174 else
Tejun Heo324a56e2013-12-11 14:11:53 -0500175 parent = kobj->sd;
Eric W. Biederman7cb32942010-02-12 19:22:25 -0800176
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700177 if (targ->sd)
Tejun Heoadc5e8b2013-12-11 14:11:54 -0500178 old_ns = targ->sd->ns;
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700179
Eric W. Biederman7cb32942010-02-12 19:22:25 -0800180 result = -ENOENT;
Tejun Heo324a56e2013-12-11 14:11:53 -0500181 kn = kernfs_find_and_get_ns(parent, old, old_ns);
182 if (!kn)
Eric W. Biederman7cb32942010-02-12 19:22:25 -0800183 goto out;
184
185 result = -EINVAL;
Tejun Heo324a56e2013-12-11 14:11:53 -0500186 if (sysfs_type(kn) != SYSFS_KOBJ_LINK)
Eric W. Biederman7cb32942010-02-12 19:22:25 -0800187 goto out;
Tejun Heoadc5e8b2013-12-11 14:11:54 -0500188 if (kn->symlink.target_kn->priv != targ)
Eric W. Biederman7cb32942010-02-12 19:22:25 -0800189 goto out;
190
Tejun Heo324a56e2013-12-11 14:11:53 -0500191 result = kernfs_rename_ns(kn, parent, new, new_ns);
Eric W. Biederman7cb32942010-02-12 19:22:25 -0800192
193out:
Tejun Heo324a56e2013-12-11 14:11:53 -0500194 kernfs_put(kn);
Eric W. Biederman7cb32942010-02-12 19:22:25 -0800195 return result;
196}
Tejun Heo4b30ee52013-09-11 22:29:06 -0400197EXPORT_SYMBOL_GPL(sysfs_rename_link_ns);