Loading...
1/*
2 * 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.
11 */
12
13#include <linux/fs.h>
14#include <linux/module.h>
15#include <linux/kobject.h>
16#include <linux/mutex.h>
17#include <linux/security.h>
18
19#include "sysfs.h"
20
21static int sysfs_do_create_link_sd(struct kernfs_node *parent,
22 struct kobject *target_kobj,
23 const char *name, int warn)
24{
25 struct kernfs_node *kn, *target = NULL;
26
27 BUG_ON(!name || !parent);
28
29 /*
30 * We don't own @target_kobj and it may be removed at any time.
31 * Synchronize using sysfs_symlink_target_lock. See
32 * sysfs_remove_dir() for details.
33 */
34 spin_lock(&sysfs_symlink_target_lock);
35 if (target_kobj->sd) {
36 target = target_kobj->sd;
37 kernfs_get(target);
38 }
39 spin_unlock(&sysfs_symlink_target_lock);
40
41 if (!target)
42 return -ENOENT;
43
44 kn = kernfs_create_link(parent, name, target);
45 kernfs_put(target);
46
47 if (!IS_ERR(kn))
48 return 0;
49
50 if (warn && PTR_ERR(kn) == -EEXIST)
51 sysfs_warn_dup(parent, name);
52 return PTR_ERR(kn);
53}
54
55/**
56 * sysfs_create_link_sd - create symlink to a given object.
57 * @kn: directory we're creating the link in.
58 * @target: object we're pointing to.
59 * @name: name of the symlink.
60 */
61int sysfs_create_link_sd(struct kernfs_node *kn, struct kobject *target,
62 const char *name)
63{
64 return sysfs_do_create_link_sd(kn, target, name, 1);
65}
66
67static int sysfs_do_create_link(struct kobject *kobj, struct kobject *target,
68 const char *name, int warn)
69{
70 struct kernfs_node *parent = NULL;
71
72 if (!kobj)
73 parent = sysfs_root_kn;
74 else
75 parent = kobj->sd;
76
77 if (!parent)
78 return -EFAULT;
79
80 return sysfs_do_create_link_sd(parent, target, name, warn);
81}
82
83/**
84 * 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}
94EXPORT_SYMBOL_GPL(sysfs_create_link);
95
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 *
102 * This function does the same as sysfs_create_link(), but it
103 * 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/**
112 * 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;
124
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);
131 if (targ->sd && kernfs_ns_enabled(kobj->sd))
132 ns = targ->sd->ns;
133 spin_unlock(&sysfs_symlink_target_lock);
134 kernfs_remove_by_name_ns(kobj->sd, name, ns);
135}
136
137/**
138 * 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 */
142void sysfs_remove_link(struct kobject *kobj, const char *name)
143{
144 struct kernfs_node *parent = NULL;
145
146 if (!kobj)
147 parent = sysfs_root_kn;
148 else
149 parent = kobj->sd;
150
151 kernfs_remove_by_name(parent, name);
152}
153EXPORT_SYMBOL_GPL(sysfs_remove_link);
154
155/**
156 * sysfs_rename_link_ns - rename symlink in object's directory.
157 * @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.
161 * @new_ns: new namespace of the symlink.
162 *
163 * A helper function for the common rename symlink idiom.
164 */
165int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
166 const char *old, const char *new, const void *new_ns)
167{
168 struct kernfs_node *parent, *kn = NULL;
169 const void *old_ns = NULL;
170 int result;
171
172 if (!kobj)
173 parent = sysfs_root_kn;
174 else
175 parent = kobj->sd;
176
177 if (targ->sd)
178 old_ns = targ->sd->ns;
179
180 result = -ENOENT;
181 kn = kernfs_find_and_get_ns(parent, old, old_ns);
182 if (!kn)
183 goto out;
184
185 result = -EINVAL;
186 if (kernfs_type(kn) != KERNFS_LINK)
187 goto out;
188 if (kn->symlink.target_kn->priv != targ)
189 goto out;
190
191 result = kernfs_rename_ns(kn, parent, new, new_ns);
192
193out:
194 kernfs_put(kn);
195 return result;
196}
197EXPORT_SYMBOL_GPL(sysfs_rename_link_ns);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * fs/sysfs/symlink.c - sysfs symlink implementation
4 *
5 * Copyright (c) 2001-3 Patrick Mochel
6 * Copyright (c) 2007 SUSE Linux Products GmbH
7 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
8 *
9 * Please see Documentation/filesystems/sysfs.txt for more information.
10 */
11
12#include <linux/fs.h>
13#include <linux/module.h>
14#include <linux/kobject.h>
15#include <linux/mutex.h>
16#include <linux/security.h>
17
18#include "sysfs.h"
19
20static int sysfs_do_create_link_sd(struct kernfs_node *parent,
21 struct kobject *target_kobj,
22 const char *name, int warn)
23{
24 struct kernfs_node *kn, *target = NULL;
25
26 BUG_ON(!name || !parent);
27
28 /*
29 * We don't own @target_kobj and it may be removed at any time.
30 * Synchronize using sysfs_symlink_target_lock. See
31 * sysfs_remove_dir() for details.
32 */
33 spin_lock(&sysfs_symlink_target_lock);
34 if (target_kobj->sd) {
35 target = target_kobj->sd;
36 kernfs_get(target);
37 }
38 spin_unlock(&sysfs_symlink_target_lock);
39
40 if (!target)
41 return -ENOENT;
42
43 kn = kernfs_create_link(parent, name, target);
44 kernfs_put(target);
45
46 if (!IS_ERR(kn))
47 return 0;
48
49 if (warn && PTR_ERR(kn) == -EEXIST)
50 sysfs_warn_dup(parent, name);
51 return PTR_ERR(kn);
52}
53
54/**
55 * sysfs_create_link_sd - create symlink to a given object.
56 * @kn: directory we're creating the link in.
57 * @target: object we're pointing to.
58 * @name: name of the symlink.
59 */
60int sysfs_create_link_sd(struct kernfs_node *kn, struct kobject *target,
61 const char *name)
62{
63 return sysfs_do_create_link_sd(kn, target, name, 1);
64}
65
66static int sysfs_do_create_link(struct kobject *kobj, struct kobject *target,
67 const char *name, int warn)
68{
69 struct kernfs_node *parent = NULL;
70
71 if (!kobj)
72 parent = sysfs_root_kn;
73 else
74 parent = kobj->sd;
75
76 if (!parent)
77 return -EFAULT;
78
79 return sysfs_do_create_link_sd(parent, target, name, warn);
80}
81
82/**
83 * sysfs_create_link - create symlink between two objects.
84 * @kobj: object whose directory we're creating the link in.
85 * @target: object we're pointing to.
86 * @name: name of the symlink.
87 */
88int sysfs_create_link(struct kobject *kobj, struct kobject *target,
89 const char *name)
90{
91 return sysfs_do_create_link(kobj, target, name, 1);
92}
93EXPORT_SYMBOL_GPL(sysfs_create_link);
94
95/**
96 * sysfs_create_link_nowarn - create symlink between two objects.
97 * @kobj: object whose directory we're creating the link in.
98 * @target: object we're pointing to.
99 * @name: name of the symlink.
100 *
101 * This function does the same as sysfs_create_link(), but it
102 * doesn't warn if the link already exists.
103 */
104int sysfs_create_link_nowarn(struct kobject *kobj, struct kobject *target,
105 const char *name)
106{
107 return sysfs_do_create_link(kobj, target, name, 0);
108}
109EXPORT_SYMBOL_GPL(sysfs_create_link_nowarn);
110
111/**
112 * 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;
124
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);
131 if (targ->sd && kernfs_ns_enabled(kobj->sd))
132 ns = targ->sd->ns;
133 spin_unlock(&sysfs_symlink_target_lock);
134 kernfs_remove_by_name_ns(kobj->sd, name, ns);
135}
136
137/**
138 * 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 */
142void sysfs_remove_link(struct kobject *kobj, const char *name)
143{
144 struct kernfs_node *parent = NULL;
145
146 if (!kobj)
147 parent = sysfs_root_kn;
148 else
149 parent = kobj->sd;
150
151 kernfs_remove_by_name(parent, name);
152}
153EXPORT_SYMBOL_GPL(sysfs_remove_link);
154
155/**
156 * sysfs_rename_link_ns - rename symlink in object's directory.
157 * @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.
161 * @new_ns: new namespace of the symlink.
162 *
163 * A helper function for the common rename symlink idiom.
164 */
165int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
166 const char *old, const char *new, const void *new_ns)
167{
168 struct kernfs_node *parent, *kn = NULL;
169 const void *old_ns = NULL;
170 int result;
171
172 if (!kobj)
173 parent = sysfs_root_kn;
174 else
175 parent = kobj->sd;
176
177 if (targ->sd)
178 old_ns = targ->sd->ns;
179
180 result = -ENOENT;
181 kn = kernfs_find_and_get_ns(parent, old, old_ns);
182 if (!kn)
183 goto out;
184
185 result = -EINVAL;
186 if (kernfs_type(kn) != KERNFS_LINK)
187 goto out;
188 if (kn->symlink.target_kn->priv != targ)
189 goto out;
190
191 result = kernfs_rename_ns(kn, parent, new, new_ns);
192
193out:
194 kernfs_put(kn);
195 return result;
196}
197EXPORT_SYMBOL_GPL(sysfs_rename_link_ns);