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13#include <linux/fs.h>
14#include <linux/gfp.h>
15#include <linux/mount.h>
16#include <linux/module.h>
17#include <linux/kobject.h>
18#include <linux/namei.h>
19#include <linux/mutex.h>
20#include <linux/security.h>
21
22#include "sysfs.h"
23
24static int sysfs_do_create_link(struct kobject *kobj, struct kobject *target,
25 const char *name, int warn)
26{
27 struct sysfs_dirent *parent_sd = NULL;
28 struct sysfs_dirent *target_sd = NULL;
29 struct sysfs_dirent *sd = NULL;
30 struct sysfs_addrm_cxt acxt;
31 enum kobj_ns_type ns_type;
32 int error;
33
34 BUG_ON(!name);
35
36 if (!kobj)
37 parent_sd = &sysfs_root;
38 else
39 parent_sd = kobj->sd;
40
41 error = -EFAULT;
42 if (!parent_sd)
43 goto out_put;
44
45
46
47
48 spin_lock(&sysfs_assoc_lock);
49 if (target->sd)
50 target_sd = sysfs_get(target->sd);
51 spin_unlock(&sysfs_assoc_lock);
52
53 error = -ENOENT;
54 if (!target_sd)
55 goto out_put;
56
57 error = -ENOMEM;
58 sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
59 if (!sd)
60 goto out_put;
61
62 ns_type = sysfs_ns_type(parent_sd);
63 if (ns_type)
64 sd->s_ns = target->ktype->namespace(target);
65 sd->s_symlink.target_sd = target_sd;
66 target_sd = NULL;
67
68 sysfs_addrm_start(&acxt, parent_sd);
69
70 if (!ns_type ||
71 (ns_type == sysfs_ns_type(sd->s_symlink.target_sd->s_parent))) {
72 if (warn)
73 error = sysfs_add_one(&acxt, sd);
74 else
75 error = __sysfs_add_one(&acxt, sd);
76 } else {
77 error = -EINVAL;
78 WARN(1, KERN_WARNING
79 "sysfs: symlink across ns_types %s/%s -> %s/%s\n",
80 parent_sd->s_name,
81 sd->s_name,
82 sd->s_symlink.target_sd->s_parent->s_name,
83 sd->s_symlink.target_sd->s_name);
84 }
85 sysfs_addrm_finish(&acxt);
86
87 if (error)
88 goto out_put;
89
90 return 0;
91
92 out_put:
93 sysfs_put(target_sd);
94 sysfs_put(sd);
95 return error;
96}
97
98
99
100
101
102
103
104int sysfs_create_link(struct kobject *kobj, struct kobject *target,
105 const char *name)
106{
107 return sysfs_do_create_link(kobj, target, name, 1);
108}
109
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117
118
119int sysfs_create_link_nowarn(struct kobject *kobj, struct kobject *target,
120 const char *name)
121{
122 return sysfs_do_create_link(kobj, target, name, 0);
123}
124
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131
132
133
134void sysfs_delete_link(struct kobject *kobj, struct kobject *targ,
135 const char *name)
136{
137 const void *ns = NULL;
138 spin_lock(&sysfs_assoc_lock);
139 if (targ->sd && sysfs_ns_type(kobj->sd))
140 ns = targ->sd->s_ns;
141 spin_unlock(&sysfs_assoc_lock);
142 sysfs_hash_and_remove(kobj->sd, ns, name);
143}
144
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149
150
151void sysfs_remove_link(struct kobject * kobj, const char * name)
152{
153 struct sysfs_dirent *parent_sd = NULL;
154
155 if (!kobj)
156 parent_sd = &sysfs_root;
157 else
158 parent_sd = kobj->sd;
159
160 sysfs_hash_and_remove(parent_sd, NULL, name);
161}
162
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170
171
172int sysfs_rename_link(struct kobject *kobj, struct kobject *targ,
173 const char *old, const char *new)
174{
175 struct sysfs_dirent *parent_sd, *sd = NULL;
176 const void *old_ns = NULL, *new_ns = NULL;
177 int result;
178
179 if (!kobj)
180 parent_sd = &sysfs_root;
181 else
182 parent_sd = kobj->sd;
183
184 if (targ->sd)
185 old_ns = targ->sd->s_ns;
186
187 result = -ENOENT;
188 sd = sysfs_get_dirent(parent_sd, old_ns, old);
189 if (!sd)
190 goto out;
191
192 result = -EINVAL;
193 if (sysfs_type(sd) != SYSFS_KOBJ_LINK)
194 goto out;
195 if (sd->s_symlink.target_sd->s_dir.kobj != targ)
196 goto out;
197
198 if (sysfs_ns_type(parent_sd))
199 new_ns = targ->ktype->namespace(targ);
200
201 result = sysfs_rename(sd, parent_sd, new_ns, new);
202
203out:
204 sysfs_put(sd);
205 return result;
206}
207
208static int sysfs_get_target_path(struct sysfs_dirent *parent_sd,
209 struct sysfs_dirent *target_sd, char *path)
210{
211 struct sysfs_dirent *base, *sd;
212 char *s = path;
213 int len = 0;
214
215
216 base = parent_sd;
217 while (base->s_parent) {
218 sd = target_sd->s_parent;
219 while (sd->s_parent && base != sd)
220 sd = sd->s_parent;
221
222 if (base == sd)
223 break;
224
225 strcpy(s, "../");
226 s += 3;
227 base = base->s_parent;
228 }
229
230
231 sd = target_sd;
232 while (sd->s_parent && sd != base) {
233 len += strlen(sd->s_name) + 1;
234 sd = sd->s_parent;
235 }
236
237
238 if (len < 2)
239 return -EINVAL;
240 len--;
241 if ((s - path) + len > PATH_MAX)
242 return -ENAMETOOLONG;
243
244
245 sd = target_sd;
246 while (sd->s_parent && sd != base) {
247 int slen = strlen(sd->s_name);
248
249 len -= slen;
250 strncpy(s + len, sd->s_name, slen);
251 if (len)
252 s[--len] = '/';
253
254 sd = sd->s_parent;
255 }
256
257 return 0;
258}
259
260static int sysfs_getlink(struct dentry *dentry, char * path)
261{
262 struct sysfs_dirent *sd = dentry->d_fsdata;
263 struct sysfs_dirent *parent_sd = sd->s_parent;
264 struct sysfs_dirent *target_sd = sd->s_symlink.target_sd;
265 int error;
266
267 mutex_lock(&sysfs_mutex);
268 error = sysfs_get_target_path(parent_sd, target_sd, path);
269 mutex_unlock(&sysfs_mutex);
270
271 return error;
272}
273
274static void *sysfs_follow_link(struct dentry *dentry, struct nameidata *nd)
275{
276 int error = -ENOMEM;
277 unsigned long page = get_zeroed_page(GFP_KERNEL);
278 if (page) {
279 error = sysfs_getlink(dentry, (char *) page);
280 if (error < 0)
281 free_page((unsigned long)page);
282 }
283 nd_set_link(nd, error ? ERR_PTR(error) : (char *)page);
284 return NULL;
285}
286
287static void sysfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
288{
289 char *page = nd_get_link(nd);
290 if (!IS_ERR(page))
291 free_page((unsigned long)page);
292}
293
294const struct inode_operations sysfs_symlink_inode_operations = {
295 .setxattr = sysfs_setxattr,
296 .readlink = generic_readlink,
297 .follow_link = sysfs_follow_link,
298 .put_link = sysfs_put_link,
299 .setattr = sysfs_setattr,
300 .getattr = sysfs_getattr,
301 .permission = sysfs_permission,
302};
303
304
305EXPORT_SYMBOL_GPL(sysfs_create_link);
306EXPORT_SYMBOL_GPL(sysfs_remove_link);
307EXPORT_SYMBOL_GPL(sysfs_rename_link);
308