Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * fs/kernfs/inode.c - kernfs inode implementation
4 *
5 * Copyright (c) 2001-3 Patrick Mochel
6 * Copyright (c) 2007 SUSE Linux Products GmbH
7 * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
8 */
9
10#include <linux/pagemap.h>
11#include <linux/backing-dev.h>
12#include <linux/capability.h>
13#include <linux/errno.h>
14#include <linux/slab.h>
15#include <linux/xattr.h>
16#include <linux/security.h>
17
18#include "kernfs-internal.h"
19
20static const struct inode_operations kernfs_iops = {
21 .permission = kernfs_iop_permission,
22 .setattr = kernfs_iop_setattr,
23 .getattr = kernfs_iop_getattr,
24 .listxattr = kernfs_iop_listxattr,
25};
26
27static struct kernfs_iattrs *__kernfs_iattrs(struct kernfs_node *kn, bool alloc)
28{
29 struct kernfs_iattrs *ret __free(kfree) = NULL;
30 struct kernfs_iattrs *attr;
31
32 attr = READ_ONCE(kn->iattr);
33 if (attr || !alloc)
34 return attr;
35
36 ret = kmem_cache_zalloc(kernfs_iattrs_cache, GFP_KERNEL);
37 if (!ret)
38 return NULL;
39
40 /* assign default attributes */
41 ret->ia_uid = GLOBAL_ROOT_UID;
42 ret->ia_gid = GLOBAL_ROOT_GID;
43
44 ktime_get_real_ts64(&ret->ia_atime);
45 ret->ia_mtime = ret->ia_atime;
46 ret->ia_ctime = ret->ia_atime;
47
48 simple_xattr_limits_init(&ret->xattr_limits);
49
50 /* If someone raced us, recognize it. */
51 if (!try_cmpxchg(&kn->iattr, &attr, ret))
52 return READ_ONCE(kn->iattr);
53
54 return no_free_ptr(ret);
55}
56
57static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
58{
59 return __kernfs_iattrs(kn, true);
60}
61
62static struct kernfs_iattrs *kernfs_iattrs_noalloc(struct kernfs_node *kn)
63{
64 return __kernfs_iattrs(kn, false);
65}
66
67int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
68{
69 struct kernfs_iattrs *attrs;
70 unsigned int ia_valid = iattr->ia_valid;
71
72 attrs = kernfs_iattrs(kn);
73 if (!attrs)
74 return -ENOMEM;
75
76 if (ia_valid & ATTR_UID)
77 attrs->ia_uid = iattr->ia_uid;
78 if (ia_valid & ATTR_GID)
79 attrs->ia_gid = iattr->ia_gid;
80 if (ia_valid & ATTR_ATIME)
81 attrs->ia_atime = iattr->ia_atime;
82 if (ia_valid & ATTR_MTIME)
83 attrs->ia_mtime = iattr->ia_mtime;
84 if (ia_valid & ATTR_CTIME)
85 attrs->ia_ctime = iattr->ia_ctime;
86 if (ia_valid & ATTR_MODE)
87 kn->mode = iattr->ia_mode;
88 return 0;
89}
90
91/**
92 * kernfs_setattr - set iattr on a node
93 * @kn: target node
94 * @iattr: iattr to set
95 *
96 * Return: %0 on success, -errno on failure.
97 */
98int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
99{
100 int ret;
101 struct kernfs_root *root = kernfs_root(kn);
102
103 down_write(&root->kernfs_iattr_rwsem);
104 ret = __kernfs_setattr(kn, iattr);
105 up_write(&root->kernfs_iattr_rwsem);
106 return ret;
107}
108
109int kernfs_iop_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
110 struct iattr *iattr)
111{
112 struct inode *inode = d_inode(dentry);
113 struct kernfs_node *kn = inode->i_private;
114 struct kernfs_root *root;
115 int error;
116
117 if (!kn)
118 return -EINVAL;
119
120 root = kernfs_root(kn);
121 down_write(&root->kernfs_iattr_rwsem);
122 error = setattr_prepare(&nop_mnt_idmap, dentry, iattr);
123 if (error)
124 goto out;
125
126 error = __kernfs_setattr(kn, iattr);
127 if (error)
128 goto out;
129
130 /* this ignores size changes */
131 setattr_copy(&nop_mnt_idmap, inode, iattr);
132
133out:
134 up_write(&root->kernfs_iattr_rwsem);
135 return error;
136}
137
138ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
139{
140 struct kernfs_node *kn = kernfs_dentry_node(dentry);
141 struct kernfs_iattrs *attrs;
142
143 attrs = kernfs_iattrs(kn);
144 if (!attrs)
145 return -ENOMEM;
146
147 return simple_xattr_list(d_inode(dentry), READ_ONCE(attrs->xattrs),
148 buf, size);
149}
150
151static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
152{
153 inode->i_mode = mode;
154 simple_inode_init_ts(inode);
155}
156
157static inline void set_inode_attr(struct inode *inode,
158 struct kernfs_iattrs *attrs)
159{
160 inode->i_uid = attrs->ia_uid;
161 inode->i_gid = attrs->ia_gid;
162 inode_set_atime_to_ts(inode, attrs->ia_atime);
163 inode_set_mtime_to_ts(inode, attrs->ia_mtime);
164 inode_set_ctime_to_ts(inode, attrs->ia_ctime);
165}
166
167static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
168{
169 struct kernfs_iattrs *attrs;
170
171 inode->i_mode = kn->mode;
172 attrs = kernfs_iattrs_noalloc(kn);
173 if (attrs)
174 /*
175 * kernfs_node has non-default attributes get them from
176 * persistent copy in kernfs_node.
177 */
178 set_inode_attr(inode, attrs);
179
180 if (kernfs_type(kn) == KERNFS_DIR && !(kn->flags & KERNFS_REMOVING))
181 set_nlink(inode, kn->dir.subdirs + 2);
182}
183
184int kernfs_iop_getattr(struct mnt_idmap *idmap,
185 const struct path *path, struct kstat *stat,
186 u32 request_mask, unsigned int query_flags)
187{
188 struct inode *inode = d_inode(path->dentry);
189 struct kernfs_node *kn = inode->i_private;
190 struct kernfs_root *root = kernfs_root(kn);
191
192 down_read(&root->kernfs_iattr_rwsem);
193 kernfs_refresh_inode(kn, inode);
194 generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
195 up_read(&root->kernfs_iattr_rwsem);
196
197 return 0;
198}
199
200static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
201{
202 kernfs_get(kn);
203 inode->i_private = kn;
204 inode->i_mapping->a_ops = &ram_aops;
205 inode->i_op = &kernfs_iops;
206 inode->i_generation = kernfs_gen(kn);
207
208 set_default_inode_attr(inode, kn->mode);
209 kernfs_refresh_inode(kn, inode);
210
211 /* initialize inode according to type */
212 switch (kernfs_type(kn)) {
213 case KERNFS_DIR:
214 inode->i_op = &kernfs_dir_iops;
215 inode->i_fop = &kernfs_dir_fops;
216 if (kn->flags & KERNFS_EMPTY_DIR)
217 make_empty_dir_inode(inode);
218 break;
219 case KERNFS_FILE:
220 inode->i_size = kn->attr.size;
221 inode->i_fop = &kernfs_file_fops;
222 break;
223 case KERNFS_LINK:
224 inode->i_op = &kernfs_symlink_iops;
225 break;
226 default:
227 BUG();
228 }
229
230 unlock_new_inode(inode);
231}
232
233/**
234 * kernfs_get_inode - get inode for kernfs_node
235 * @sb: super block
236 * @kn: kernfs_node to allocate inode for
237 *
238 * Get inode for @kn. If such inode doesn't exist, a new inode is
239 * allocated and basics are initialized. New inode is returned
240 * locked.
241 *
242 * Locking:
243 * Kernel thread context (may sleep).
244 *
245 * Return:
246 * Pointer to allocated inode on success, %NULL on failure.
247 */
248struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
249{
250 struct inode *inode;
251
252 inode = iget_locked(sb, kernfs_ino(kn));
253 if (inode && (inode_state_read_once(inode) & I_NEW))
254 kernfs_init_inode(kn, inode);
255
256 return inode;
257}
258
259/*
260 * The kernfs_node serves as both an inode and a directory entry for
261 * kernfs. To prevent the kernfs inode numbers from being freed
262 * prematurely we take a reference to kernfs_node from the kernfs inode. A
263 * super_operations.evict_inode() implementation is needed to drop that
264 * reference upon inode destruction.
265 */
266void kernfs_evict_inode(struct inode *inode)
267{
268 struct kernfs_node *kn = inode->i_private;
269
270 truncate_inode_pages_final(&inode->i_data);
271 clear_inode(inode);
272 kernfs_put(kn);
273}
274
275int kernfs_iop_permission(struct mnt_idmap *idmap,
276 struct inode *inode, int mask)
277{
278 struct kernfs_node *kn;
279 struct kernfs_root *root;
280 int ret;
281
282 if (mask & MAY_NOT_BLOCK)
283 return -ECHILD;
284
285 kn = inode->i_private;
286 root = kernfs_root(kn);
287
288 down_read(&root->kernfs_iattr_rwsem);
289 kernfs_refresh_inode(kn, inode);
290 ret = generic_permission(&nop_mnt_idmap, inode, mask);
291 up_read(&root->kernfs_iattr_rwsem);
292
293 return ret;
294}
295
296int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
297 void *value, size_t size)
298{
299 struct kernfs_iattrs *attrs = kernfs_iattrs_noalloc(kn);
300 struct simple_xattrs *xattrs;
301
302 if (!attrs)
303 return -ENODATA;
304
305 xattrs = READ_ONCE(attrs->xattrs);
306 if (!xattrs)
307 return -ENODATA;
308
309 return simple_xattr_get(xattrs, name, value, size);
310}
311
312int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
313 const void *value, size_t size, int flags)
314{
315 struct simple_xattr *old_xattr;
316 struct simple_xattrs *xattrs;
317 struct kernfs_iattrs *attrs;
318
319 attrs = kernfs_iattrs(kn);
320 if (!attrs)
321 return -ENOMEM;
322
323 xattrs = simple_xattrs_lazy_alloc(&attrs->xattrs, value, flags);
324 if (IS_ERR_OR_NULL(xattrs))
325 return PTR_ERR(xattrs);
326
327 old_xattr = simple_xattr_set(xattrs, name, value, size, flags);
328 if (IS_ERR(old_xattr))
329 return PTR_ERR(old_xattr);
330
331 simple_xattr_free_rcu(old_xattr);
332 return 0;
333}
334
335static int kernfs_vfs_xattr_get(const struct xattr_handler *handler,
336 struct dentry *unused, struct inode *inode,
337 const char *suffix, void *value, size_t size)
338{
339 const char *name = xattr_full_name(handler, suffix);
340 struct kernfs_node *kn = inode->i_private;
341
342 return kernfs_xattr_get(kn, name, value, size);
343}
344
345static int kernfs_vfs_xattr_set(const struct xattr_handler *handler,
346 struct mnt_idmap *idmap,
347 struct dentry *unused, struct inode *inode,
348 const char *suffix, const void *value,
349 size_t size, int flags)
350{
351 const char *name = xattr_full_name(handler, suffix);
352 struct kernfs_node *kn = inode->i_private;
353
354 return kernfs_xattr_set(kn, name, value, size, flags);
355}
356
357static int kernfs_vfs_user_xattr_set(const struct xattr_handler *handler,
358 struct mnt_idmap *idmap,
359 struct dentry *unused, struct inode *inode,
360 const char *suffix, const void *value,
361 size_t size, int flags)
362{
363 const char *full_name = xattr_full_name(handler, suffix);
364 struct kernfs_node *kn = inode->i_private;
365 struct simple_xattrs *xattrs;
366 struct kernfs_iattrs *attrs;
367
368 if (!(kernfs_root(kn)->flags & KERNFS_ROOT_SUPPORT_USER_XATTR))
369 return -EOPNOTSUPP;
370
371 attrs = kernfs_iattrs(kn);
372 if (!attrs)
373 return -ENOMEM;
374
375 xattrs = simple_xattrs_lazy_alloc(&attrs->xattrs, value, flags);
376 if (IS_ERR_OR_NULL(xattrs))
377 return PTR_ERR(xattrs);
378
379 return simple_xattr_set_limited(xattrs, &attrs->xattr_limits,
380 full_name, value, size, flags);
381}
382
383static const struct xattr_handler kernfs_trusted_xattr_handler = {
384 .prefix = XATTR_TRUSTED_PREFIX,
385 .get = kernfs_vfs_xattr_get,
386 .set = kernfs_vfs_xattr_set,
387};
388
389static const struct xattr_handler kernfs_security_xattr_handler = {
390 .prefix = XATTR_SECURITY_PREFIX,
391 .get = kernfs_vfs_xattr_get,
392 .set = kernfs_vfs_xattr_set,
393};
394
395static const struct xattr_handler kernfs_user_xattr_handler = {
396 .prefix = XATTR_USER_PREFIX,
397 .get = kernfs_vfs_xattr_get,
398 .set = kernfs_vfs_user_xattr_set,
399};
400
401const struct xattr_handler * const kernfs_xattr_handlers[] = {
402 &kernfs_trusted_xattr_handler,
403 &kernfs_security_xattr_handler,
404 &kernfs_user_xattr_handler,
405 NULL
406};