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Miklos Szeredie9be9d52014-10-24 00:14:38 +02001/*
2 *
3 * Copyright (C) 2011 Novell Inc.
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 as published by
7 * the Free Software Foundation.
8 */
9
10#include <linux/fs.h>
11#include <linux/namei.h>
Miklos Szeredicf9a6782015-12-11 16:30:49 +010012#include <linux/pagemap.h>
Miklos Szeredie9be9d52014-10-24 00:14:38 +020013#include <linux/xattr.h>
14#include <linux/security.h>
15#include <linux/mount.h>
16#include <linux/slab.h>
17#include <linux/parser.h>
18#include <linux/module.h>
19#include <linux/sched.h>
Andy Whitcroftcc259632014-10-24 00:14:38 +020020#include <linux/statfs.h>
Erez Zadokf45827e82014-10-24 00:14:38 +020021#include <linux/seq_file.h>
Miklos Szeredid837a492016-07-29 12:05:24 +020022#include <linux/posix_acl_xattr.h>
Miklos Szeredie9be9d52014-10-24 00:14:38 +020023#include "overlayfs.h"
24
25MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
26MODULE_DESCRIPTION("Overlay filesystem");
27MODULE_LICENSE("GPL");
28
Erez Zadokf45827e82014-10-24 00:14:38 +020029struct ovl_config {
30 char *lowerdir;
31 char *upperdir;
32 char *workdir;
Miklos Szeredi8d3095f2015-10-12 17:11:44 +020033 bool default_permissions;
Erez Zadokf45827e82014-10-24 00:14:38 +020034};
35
Miklos Szeredie9be9d52014-10-24 00:14:38 +020036/* private information held for overlayfs's superblock */
37struct ovl_fs {
38 struct vfsmount *upper_mnt;
Miklos Szeredidd662662014-12-13 00:59:43 +010039 unsigned numlower;
40 struct vfsmount **lower_mnt;
Miklos Szeredie9be9d52014-10-24 00:14:38 +020041 struct dentry *workdir;
Andy Whitcroftcc259632014-10-24 00:14:38 +020042 long lower_namelen;
Erez Zadokf45827e82014-10-24 00:14:38 +020043 /* pathnames of lower and upper dirs, for show_options */
44 struct ovl_config config;
Antonio Murdaca3fe6e522016-04-07 15:48:25 +020045 /* creds of process who forced instantiation of super block */
46 const struct cred *creator_cred;
Miklos Szeredie9be9d52014-10-24 00:14:38 +020047};
48
49struct ovl_dir_cache;
50
51/* private information held for every overlayfs dentry */
52struct ovl_entry {
53 struct dentry *__upperdentry;
Miklos Szeredie9be9d52014-10-24 00:14:38 +020054 struct ovl_dir_cache *cache;
55 union {
56 struct {
57 u64 version;
58 bool opaque;
59 };
60 struct rcu_head rcu;
61 };
Miklos Szeredidd662662014-12-13 00:59:43 +010062 unsigned numlower;
63 struct path lowerstack[];
Miklos Szeredie9be9d52014-10-24 00:14:38 +020064};
65
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +010066#define OVL_MAX_STACK 500
67
Miklos Szeredidd662662014-12-13 00:59:43 +010068static struct dentry *__ovl_dentry_lower(struct ovl_entry *oe)
69{
70 return oe->numlower ? oe->lowerstack[0].dentry : NULL;
71}
Miklos Szeredie9be9d52014-10-24 00:14:38 +020072
73enum ovl_path_type ovl_path_type(struct dentry *dentry)
74{
75 struct ovl_entry *oe = dentry->d_fsdata;
Miklos Szeredi1afaba12014-12-13 00:59:42 +010076 enum ovl_path_type type = 0;
Miklos Szeredie9be9d52014-10-24 00:14:38 +020077
78 if (oe->__upperdentry) {
Miklos Szeredi1afaba12014-12-13 00:59:42 +010079 type = __OVL_PATH_UPPER;
80
Konstantin Khlebnikov45d11732016-01-31 16:17:53 +030081 /*
82 * Non-dir dentry can hold lower dentry from previous
83 * location. Its purity depends only on opaque flag.
84 */
85 if (oe->numlower && S_ISDIR(dentry->d_inode->i_mode))
86 type |= __OVL_PATH_MERGE;
87 else if (!oe->opaque)
Miklos Szeredi1afaba12014-12-13 00:59:42 +010088 type |= __OVL_PATH_PURE;
Miklos Szeredi9d7459d2014-12-13 00:59:44 +010089 } else {
90 if (oe->numlower > 1)
91 type |= __OVL_PATH_MERGE;
Miklos Szeredie9be9d52014-10-24 00:14:38 +020092 }
Miklos Szeredi1afaba12014-12-13 00:59:42 +010093 return type;
Miklos Szeredie9be9d52014-10-24 00:14:38 +020094}
95
96static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
97{
Miklos Szeredi71d50922014-11-20 16:40:01 +010098 return lockless_dereference(oe->__upperdentry);
Miklos Szeredie9be9d52014-10-24 00:14:38 +020099}
100
101void ovl_path_upper(struct dentry *dentry, struct path *path)
102{
103 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
104 struct ovl_entry *oe = dentry->d_fsdata;
105
106 path->mnt = ofs->upper_mnt;
107 path->dentry = ovl_upperdentry_dereference(oe);
108}
109
110enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
111{
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200112 enum ovl_path_type type = ovl_path_type(dentry);
113
Miklos Szeredi1afaba12014-12-13 00:59:42 +0100114 if (!OVL_TYPE_UPPER(type))
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200115 ovl_path_lower(dentry, path);
116 else
117 ovl_path_upper(dentry, path);
118
119 return type;
120}
121
122struct dentry *ovl_dentry_upper(struct dentry *dentry)
123{
124 struct ovl_entry *oe = dentry->d_fsdata;
125
126 return ovl_upperdentry_dereference(oe);
127}
128
129struct dentry *ovl_dentry_lower(struct dentry *dentry)
130{
131 struct ovl_entry *oe = dentry->d_fsdata;
132
Miklos Szeredidd662662014-12-13 00:59:43 +0100133 return __ovl_dentry_lower(oe);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200134}
135
136struct dentry *ovl_dentry_real(struct dentry *dentry)
137{
138 struct ovl_entry *oe = dentry->d_fsdata;
139 struct dentry *realdentry;
140
141 realdentry = ovl_upperdentry_dereference(oe);
142 if (!realdentry)
Miklos Szeredidd662662014-12-13 00:59:43 +0100143 realdentry = __ovl_dentry_lower(oe);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200144
145 return realdentry;
146}
147
Miklos Szeredi39b681f2016-07-29 12:05:24 +0200148static void ovl_inode_init(struct inode *inode, struct inode *realinode,
149 bool is_upper)
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200150{
Miklos Szeredi39b681f2016-07-29 12:05:24 +0200151 WRITE_ONCE(inode->i_private, (unsigned long) realinode |
152 (is_upper ? OVL_ISUPPER_MASK : 0));
Vivek Goyal39a25b22016-07-01 16:34:26 -0400153}
154
Miklos Szeredi8d3095f2015-10-12 17:11:44 +0200155struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode,
156 bool is_upper)
157{
158 if (is_upper) {
159 struct ovl_fs *ofs = inode->i_sb->s_fs_info;
160
161 return ofs->upper_mnt;
162 } else {
163 return oe->numlower ? oe->lowerstack[0].mnt : NULL;
164 }
165}
166
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200167struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
168{
169 struct ovl_entry *oe = dentry->d_fsdata;
170
171 return oe->cache;
172}
173
174void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)
175{
176 struct ovl_entry *oe = dentry->d_fsdata;
177
178 oe->cache = cache;
179}
180
181void ovl_path_lower(struct dentry *dentry, struct path *path)
182{
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200183 struct ovl_entry *oe = dentry->d_fsdata;
184
Miklos Szeredidd662662014-12-13 00:59:43 +0100185 *path = oe->numlower ? oe->lowerstack[0] : (struct path) { NULL, NULL };
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200186}
187
188int ovl_want_write(struct dentry *dentry)
189{
190 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
191 return mnt_want_write(ofs->upper_mnt);
192}
193
194void ovl_drop_write(struct dentry *dentry)
195{
196 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
197 mnt_drop_write(ofs->upper_mnt);
198}
199
200struct dentry *ovl_workdir(struct dentry *dentry)
201{
202 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
203 return ofs->workdir;
204}
205
206bool ovl_dentry_is_opaque(struct dentry *dentry)
207{
208 struct ovl_entry *oe = dentry->d_fsdata;
209 return oe->opaque;
210}
211
212void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque)
213{
214 struct ovl_entry *oe = dentry->d_fsdata;
215 oe->opaque = opaque;
216}
217
218void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry)
219{
220 struct ovl_entry *oe = dentry->d_fsdata;
221
Al Viro59551022016-01-22 15:40:57 -0500222 WARN_ON(!inode_is_locked(upperdentry->d_parent->d_inode));
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200223 WARN_ON(oe->__upperdentry);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200224 /*
225 * Make sure upperdentry is consistent before making it visible to
226 * ovl_upperdentry_dereference().
227 */
228 smp_wmb();
229 oe->__upperdentry = upperdentry;
230}
231
Miklos Szeredi39b681f2016-07-29 12:05:24 +0200232void ovl_inode_update(struct inode *inode, struct inode *upperinode)
233{
234 WARN_ON(!upperinode);
Miklos Szeredi51f7e522016-07-29 12:05:24 +0200235 WARN_ON(!inode_unhashed(inode));
Miklos Szeredi39b681f2016-07-29 12:05:24 +0200236 WRITE_ONCE(inode->i_private,
237 (unsigned long) upperinode | OVL_ISUPPER_MASK);
Miklos Szeredi51f7e522016-07-29 12:05:24 +0200238 if (!S_ISDIR(upperinode->i_mode))
239 __insert_inode_hash(inode, (unsigned long) upperinode);
Miklos Szeredi39b681f2016-07-29 12:05:24 +0200240}
241
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200242void ovl_dentry_version_inc(struct dentry *dentry)
243{
244 struct ovl_entry *oe = dentry->d_fsdata;
245
Al Viro59551022016-01-22 15:40:57 -0500246 WARN_ON(!inode_is_locked(dentry->d_inode));
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200247 oe->version++;
248}
249
250u64 ovl_dentry_version_get(struct dentry *dentry)
251{
252 struct ovl_entry *oe = dentry->d_fsdata;
253
Al Viro59551022016-01-22 15:40:57 -0500254 WARN_ON(!inode_is_locked(dentry->d_inode));
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200255 return oe->version;
256}
257
258bool ovl_is_whiteout(struct dentry *dentry)
259{
260 struct inode *inode = dentry->d_inode;
261
262 return inode && IS_WHITEOUT(inode);
263}
264
Antonio Murdaca3fe6e522016-04-07 15:48:25 +0200265const struct cred *ovl_override_creds(struct super_block *sb)
266{
267 struct ovl_fs *ofs = sb->s_fs_info;
268
269 return override_creds(ofs->creator_cred);
270}
271
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200272static bool ovl_is_opaquedir(struct dentry *dentry)
273{
274 int res;
275 char val;
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200276
Miklos Szeredi2b6bc7f2016-09-16 14:12:11 +0200277 if (!d_is_dir(dentry))
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200278 return false;
279
Miklos Szeredi2b6bc7f2016-09-16 14:12:11 +0200280 res = vfs_getxattr(dentry, OVL_XATTR_OPAQUE, &val, 1);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200281 if (res == 1 && val == 'y')
282 return true;
283
284 return false;
285}
286
287static void ovl_dentry_release(struct dentry *dentry)
288{
289 struct ovl_entry *oe = dentry->d_fsdata;
290
291 if (oe) {
Miklos Szeredidd662662014-12-13 00:59:43 +0100292 unsigned int i;
293
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200294 dput(oe->__upperdentry);
Miklos Szeredidd662662014-12-13 00:59:43 +0100295 for (i = 0; i < oe->numlower; i++)
296 dput(oe->lowerstack[i].dentry);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200297 kfree_rcu(oe, rcu);
298 }
299}
300
Miklos Szeredi2d902672016-06-30 08:53:27 +0200301static struct dentry *ovl_d_real(struct dentry *dentry,
302 const struct inode *inode,
303 unsigned int open_flags)
Miklos Szeredid101a122016-03-26 16:14:37 -0400304{
305 struct dentry *real;
306
307 if (d_is_dir(dentry)) {
308 if (!inode || inode == d_inode(dentry))
309 return dentry;
310 goto bug;
311 }
312
Miklos Szeredi2d902672016-06-30 08:53:27 +0200313 if (d_is_negative(dentry))
314 return dentry;
315
316 if (open_flags) {
317 int err = ovl_open_maybe_copy_up(dentry, open_flags);
318
319 if (err)
320 return ERR_PTR(err);
321 }
322
Miklos Szeredid101a122016-03-26 16:14:37 -0400323 real = ovl_dentry_upper(dentry);
324 if (real && (!inode || inode == d_inode(real)))
325 return real;
326
327 real = ovl_dentry_lower(dentry);
328 if (!real)
329 goto bug;
330
Miklos Szeredic4fcfc12016-11-29 10:20:24 +0100331 /* Handle recursion */
332 real = d_real(real, inode, open_flags);
333
Miklos Szeredid101a122016-03-26 16:14:37 -0400334 if (!inode || inode == d_inode(real))
335 return real;
Miklos Szeredid101a122016-03-26 16:14:37 -0400336bug:
Miklos Szeredi656189d2016-07-29 12:05:24 +0200337 WARN(1, "ovl_d_real(%pd4, %s:%lu): real dentry not found\n", dentry,
Miklos Szeredid101a122016-03-26 16:14:37 -0400338 inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0);
339 return dentry;
340}
341
Miklos Szeredi7c03b5d2015-06-22 13:53:48 +0200342static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags)
343{
344 struct ovl_entry *oe = dentry->d_fsdata;
345 unsigned int i;
346 int ret = 1;
347
348 for (i = 0; i < oe->numlower; i++) {
349 struct dentry *d = oe->lowerstack[i].dentry;
350
351 if (d->d_flags & DCACHE_OP_REVALIDATE) {
352 ret = d->d_op->d_revalidate(d, flags);
353 if (ret < 0)
354 return ret;
355 if (!ret) {
356 if (!(flags & LOOKUP_RCU))
357 d_invalidate(d);
358 return -ESTALE;
359 }
360 }
361 }
362 return 1;
363}
364
365static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
366{
367 struct ovl_entry *oe = dentry->d_fsdata;
368 unsigned int i;
369 int ret = 1;
370
371 for (i = 0; i < oe->numlower; i++) {
372 struct dentry *d = oe->lowerstack[i].dentry;
373
374 if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) {
375 ret = d->d_op->d_weak_revalidate(d, flags);
376 if (ret <= 0)
377 break;
378 }
379 }
380 return ret;
381}
382
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200383static const struct dentry_operations ovl_dentry_operations = {
384 .d_release = ovl_dentry_release,
Miklos Szeredid101a122016-03-26 16:14:37 -0400385 .d_real = ovl_d_real,
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200386};
387
Miklos Szeredi7c03b5d2015-06-22 13:53:48 +0200388static const struct dentry_operations ovl_reval_dentry_operations = {
389 .d_release = ovl_dentry_release,
Miklos Szeredid101a122016-03-26 16:14:37 -0400390 .d_real = ovl_d_real,
Miklos Szeredi7c03b5d2015-06-22 13:53:48 +0200391 .d_revalidate = ovl_dentry_revalidate,
392 .d_weak_revalidate = ovl_dentry_weak_revalidate,
393};
394
Miklos Szeredidd662662014-12-13 00:59:43 +0100395static struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200396{
Miklos Szeredidd662662014-12-13 00:59:43 +0100397 size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
398 struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
399
400 if (oe)
401 oe->numlower = numlower;
402
403 return oe;
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200404}
405
Miklos Szeredi7c03b5d2015-06-22 13:53:48 +0200406static bool ovl_dentry_remote(struct dentry *dentry)
407{
408 return dentry->d_flags &
Miklos Szeredi76bc8e22016-07-29 12:05:24 +0200409 (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE |
410 DCACHE_OP_REAL);
Miklos Szeredi7c03b5d2015-06-22 13:53:48 +0200411}
412
413static bool ovl_dentry_weird(struct dentry *dentry)
414{
415 return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
416 DCACHE_MANAGE_TRANSIT |
417 DCACHE_OP_HASH |
418 DCACHE_OP_COMPARE);
419}
420
Miklos Szeredi2b6bc7f2016-09-16 14:12:11 +0200421static inline struct dentry *ovl_lookup_real(struct dentry *dir,
Al Viro29c42e82016-07-20 22:36:53 -0400422 const struct qstr *name)
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200423{
424 struct dentry *dentry;
425
Miklos Szeredic1b2cc12016-07-29 12:05:22 +0200426 dentry = lookup_one_len_unlocked(name->name, dir, name->len);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200427
428 if (IS_ERR(dentry)) {
429 if (PTR_ERR(dentry) == -ENOENT)
430 dentry = NULL;
431 } else if (!dentry->d_inode) {
432 dput(dentry);
433 dentry = NULL;
Miklos Szeredi7c03b5d2015-06-22 13:53:48 +0200434 } else if (ovl_dentry_weird(dentry)) {
Miklos Szeredia6f15d92015-06-22 13:53:48 +0200435 dput(dentry);
Miklos Szeredi7c03b5d2015-06-22 13:53:48 +0200436 /* Don't support traversing automounts and other weirdness */
Miklos Szeredia6f15d92015-06-22 13:53:48 +0200437 dentry = ERR_PTR(-EREMOTE);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200438 }
439 return dentry;
440}
441
Miklos Szeredi5ef88da2014-12-13 00:59:43 +0100442/*
443 * Returns next layer in stack starting from top.
444 * Returns -1 if this is the last layer.
445 */
446int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
447{
448 struct ovl_entry *oe = dentry->d_fsdata;
449
450 BUG_ON(idx < 0);
451 if (idx == 0) {
452 ovl_path_upper(dentry, path);
453 if (path->dentry)
454 return oe->numlower ? 1 : -1;
455 idx++;
456 }
457 BUG_ON(idx > oe->numlower);
458 *path = oe->lowerstack[idx - 1];
459
460 return (idx < oe->numlower) ? idx + 1 : -1;
461}
462
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200463struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
464 unsigned int flags)
465{
466 struct ovl_entry *oe;
Miklos Szeredi2b6bc7f2016-09-16 14:12:11 +0200467 const struct cred *old_cred;
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100468 struct ovl_entry *poe = dentry->d_parent->d_fsdata;
469 struct path *stack = NULL;
470 struct dentry *upperdir, *upperdentry = NULL;
471 unsigned int ctr = 0;
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200472 struct inode *inode = NULL;
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100473 bool upperopaque = false;
474 struct dentry *this, *prev = NULL;
475 unsigned int i;
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200476 int err;
477
Miklos Szeredi2b6bc7f2016-09-16 14:12:11 +0200478 old_cred = ovl_override_creds(dentry->d_sb);
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100479 upperdir = ovl_upperdentry_dereference(poe);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200480 if (upperdir) {
Miklos Szeredi2b6bc7f2016-09-16 14:12:11 +0200481 this = ovl_lookup_real(upperdir, &dentry->d_name);
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100482 err = PTR_ERR(this);
483 if (IS_ERR(this))
484 goto out;
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200485
Miklos Szeredi3e01cee2014-12-13 00:59:45 +0100486 if (this) {
Miklos Szeredi7c03b5d2015-06-22 13:53:48 +0200487 if (unlikely(ovl_dentry_remote(this))) {
488 dput(this);
489 err = -EREMOTE;
490 goto out;
491 }
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100492 if (ovl_is_whiteout(this)) {
493 dput(this);
494 this = NULL;
495 upperopaque = true;
Miklos Szeredi3e01cee2014-12-13 00:59:45 +0100496 } else if (poe->numlower && ovl_is_opaquedir(this)) {
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100497 upperopaque = true;
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200498 }
499 }
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100500 upperdentry = prev = this;
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200501 }
502
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100503 if (!upperopaque && poe->numlower) {
504 err = -ENOMEM;
505 stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL);
506 if (!stack)
507 goto out_put_upper;
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200508 }
509
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100510 for (i = 0; !upperopaque && i < poe->numlower; i++) {
511 bool opaque = false;
512 struct path lowerpath = poe->lowerstack[i];
513
Miklos Szeredi2b6bc7f2016-09-16 14:12:11 +0200514 this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name);
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100515 err = PTR_ERR(this);
Miklos Szeredi09e10322014-12-13 00:59:45 +0100516 if (IS_ERR(this)) {
517 /*
518 * If it's positive, then treat ENAMETOOLONG as ENOENT.
519 */
520 if (err == -ENAMETOOLONG && (upperdentry || ctr))
521 continue;
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100522 goto out_put;
Miklos Szeredi09e10322014-12-13 00:59:45 +0100523 }
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100524 if (!this)
525 continue;
Miklos Szeredi3e01cee2014-12-13 00:59:45 +0100526 if (ovl_is_whiteout(this)) {
527 dput(this);
528 break;
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100529 }
530 /*
Miklos Szeredi3e01cee2014-12-13 00:59:45 +0100531 * Only makes sense to check opaque dir if this is not the
532 * lowermost layer.
533 */
534 if (i < poe->numlower - 1 && ovl_is_opaquedir(this))
535 opaque = true;
hujianyanga425c032015-01-06 16:10:01 +0800536
537 if (prev && (!S_ISDIR(prev->d_inode->i_mode) ||
538 !S_ISDIR(this->d_inode->i_mode))) {
539 /*
540 * FIXME: check for upper-opaqueness maybe better done
541 * in remove code.
542 */
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100543 if (prev == upperdentry)
544 upperopaque = true;
545 dput(this);
546 break;
547 }
hujianyanga425c032015-01-06 16:10:01 +0800548 /*
549 * If this is a non-directory then stop here.
550 */
551 if (!S_ISDIR(this->d_inode->i_mode))
552 opaque = true;
553
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100554 stack[ctr].dentry = this;
555 stack[ctr].mnt = lowerpath.mnt;
556 ctr++;
557 prev = this;
558 if (opaque)
559 break;
560 }
561
562 oe = ovl_alloc_entry(ctr);
563 err = -ENOMEM;
564 if (!oe)
565 goto out_put;
566
567 if (upperdentry || ctr) {
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200568 struct dentry *realdentry;
Miklos Szeredi39b681f2016-07-29 12:05:24 +0200569 struct inode *realinode;
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200570
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100571 realdentry = upperdentry ? upperdentry : stack[0].dentry;
Miklos Szeredi39b681f2016-07-29 12:05:24 +0200572 realinode = d_inode(realdentry);
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100573
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200574 err = -ENOMEM;
Miklos Szeredi51f7e522016-07-29 12:05:24 +0200575 if (upperdentry && !d_is_dir(upperdentry)) {
576 inode = ovl_get_inode(dentry->d_sb, realinode);
577 } else {
578 inode = ovl_new_inode(dentry->d_sb, realinode->i_mode);
579 if (inode)
580 ovl_inode_init(inode, realinode, !!upperdentry);
581 }
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200582 if (!inode)
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100583 goto out_free_oe;
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200584 ovl_copyattr(realdentry->d_inode, inode);
585 }
586
Miklos Szeredi2b6bc7f2016-09-16 14:12:11 +0200587 revert_creds(old_cred);
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100588 oe->opaque = upperopaque;
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200589 oe->__upperdentry = upperdentry;
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100590 memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);
591 kfree(stack);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200592 dentry->d_fsdata = oe;
593 d_add(dentry, inode);
594
595 return NULL;
596
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100597out_free_oe:
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200598 kfree(oe);
Miklos Szeredi3d3c6b82014-12-13 00:59:44 +0100599out_put:
600 for (i = 0; i < ctr; i++)
601 dput(stack[i].dentry);
602 kfree(stack);
603out_put_upper:
604 dput(upperdentry);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200605out:
Miklos Szeredi2b6bc7f2016-09-16 14:12:11 +0200606 revert_creds(old_cred);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200607 return ERR_PTR(err);
608}
609
610struct file *ovl_path_open(struct path *path, int flags)
611{
Miklos Szeredid719e8f2016-07-29 12:05:23 +0200612 return dentry_open(path, flags | O_NOATIME, current_cred());
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200613}
614
615static void ovl_put_super(struct super_block *sb)
616{
617 struct ovl_fs *ufs = sb->s_fs_info;
Miklos Szeredidd662662014-12-13 00:59:43 +0100618 unsigned i;
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200619
620 dput(ufs->workdir);
621 mntput(ufs->upper_mnt);
Miklos Szeredidd662662014-12-13 00:59:43 +0100622 for (i = 0; i < ufs->numlower; i++)
623 mntput(ufs->lower_mnt[i]);
Konstantin Khlebnikov5ffdbe82015-08-24 15:57:19 +0300624 kfree(ufs->lower_mnt);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200625
Erez Zadokf45827e82014-10-24 00:14:38 +0200626 kfree(ufs->config.lowerdir);
627 kfree(ufs->config.upperdir);
628 kfree(ufs->config.workdir);
Antonio Murdaca3fe6e522016-04-07 15:48:25 +0200629 put_cred(ufs->creator_cred);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200630 kfree(ufs);
631}
632
Andy Whitcroftcc259632014-10-24 00:14:38 +0200633/**
634 * ovl_statfs
635 * @sb: The overlayfs super block
636 * @buf: The struct kstatfs to fill in with stats
637 *
638 * Get the filesystem statistics. As writes always target the upper layer
Miklos Szeredi4ebc5812014-12-13 00:59:46 +0100639 * filesystem pass the statfs to the upper filesystem (if it exists)
Andy Whitcroftcc259632014-10-24 00:14:38 +0200640 */
641static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
642{
643 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
644 struct dentry *root_dentry = dentry->d_sb->s_root;
645 struct path path;
646 int err;
647
Miklos Szeredi4ebc5812014-12-13 00:59:46 +0100648 ovl_path_real(root_dentry, &path);
Andy Whitcroftcc259632014-10-24 00:14:38 +0200649
650 err = vfs_statfs(&path, buf);
651 if (!err) {
652 buf->f_namelen = max(buf->f_namelen, ofs->lower_namelen);
653 buf->f_type = OVERLAYFS_SUPER_MAGIC;
654 }
655
656 return err;
657}
658
Erez Zadokf45827e82014-10-24 00:14:38 +0200659/**
660 * ovl_show_options
661 *
662 * Prints the mount options for a given superblock.
663 * Returns zero; does not fail.
664 */
665static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
666{
667 struct super_block *sb = dentry->d_sb;
668 struct ovl_fs *ufs = sb->s_fs_info;
669
Kees Cooka068acf2015-09-04 15:44:57 -0700670 seq_show_option(m, "lowerdir", ufs->config.lowerdir);
Miklos Szeredi53a08cb2014-12-13 00:59:51 +0100671 if (ufs->config.upperdir) {
Kees Cooka068acf2015-09-04 15:44:57 -0700672 seq_show_option(m, "upperdir", ufs->config.upperdir);
673 seq_show_option(m, "workdir", ufs->config.workdir);
Miklos Szeredi53a08cb2014-12-13 00:59:51 +0100674 }
Miklos Szeredi8d3095f2015-10-12 17:11:44 +0200675 if (ufs->config.default_permissions)
676 seq_puts(m, ",default_permissions");
Erez Zadokf45827e82014-10-24 00:14:38 +0200677 return 0;
678}
679
Seunghun Lee3cdf6fe2015-01-03 02:26:49 +0900680static int ovl_remount(struct super_block *sb, int *flags, char *data)
681{
682 struct ovl_fs *ufs = sb->s_fs_info;
683
Miklos Szeredicc6f67b2015-05-19 14:30:12 +0200684 if (!(*flags & MS_RDONLY) && (!ufs->upper_mnt || !ufs->workdir))
Seunghun Lee3cdf6fe2015-01-03 02:26:49 +0900685 return -EROFS;
686
687 return 0;
688}
689
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200690static const struct super_operations ovl_super_operations = {
691 .put_super = ovl_put_super,
Andy Whitcroftcc259632014-10-24 00:14:38 +0200692 .statfs = ovl_statfs,
Erez Zadokf45827e82014-10-24 00:14:38 +0200693 .show_options = ovl_show_options,
Seunghun Lee3cdf6fe2015-01-03 02:26:49 +0900694 .remount_fs = ovl_remount,
Miklos Szeredieead4f22016-07-29 12:05:22 +0200695 .drop_inode = generic_delete_inode,
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200696};
697
698enum {
699 OPT_LOWERDIR,
700 OPT_UPPERDIR,
701 OPT_WORKDIR,
Miklos Szeredi8d3095f2015-10-12 17:11:44 +0200702 OPT_DEFAULT_PERMISSIONS,
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200703 OPT_ERR,
704};
705
706static const match_table_t ovl_tokens = {
707 {OPT_LOWERDIR, "lowerdir=%s"},
708 {OPT_UPPERDIR, "upperdir=%s"},
709 {OPT_WORKDIR, "workdir=%s"},
Miklos Szeredi8d3095f2015-10-12 17:11:44 +0200710 {OPT_DEFAULT_PERMISSIONS, "default_permissions"},
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200711 {OPT_ERR, NULL}
712};
713
Miklos Szeredi91c77942014-11-20 16:40:00 +0100714static char *ovl_next_opt(char **s)
715{
716 char *sbegin = *s;
717 char *p;
718
719 if (sbegin == NULL)
720 return NULL;
721
722 for (p = sbegin; *p; p++) {
723 if (*p == '\\') {
724 p++;
725 if (!*p)
726 break;
727 } else if (*p == ',') {
728 *p = '\0';
729 *s = p + 1;
730 return sbegin;
731 }
732 }
733 *s = NULL;
734 return sbegin;
735}
736
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200737static int ovl_parse_opt(char *opt, struct ovl_config *config)
738{
739 char *p;
740
Miklos Szeredi91c77942014-11-20 16:40:00 +0100741 while ((p = ovl_next_opt(&opt)) != NULL) {
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200742 int token;
743 substring_t args[MAX_OPT_ARGS];
744
745 if (!*p)
746 continue;
747
748 token = match_token(p, ovl_tokens, args);
749 switch (token) {
750 case OPT_UPPERDIR:
751 kfree(config->upperdir);
752 config->upperdir = match_strdup(&args[0]);
753 if (!config->upperdir)
754 return -ENOMEM;
755 break;
756
757 case OPT_LOWERDIR:
758 kfree(config->lowerdir);
759 config->lowerdir = match_strdup(&args[0]);
760 if (!config->lowerdir)
761 return -ENOMEM;
762 break;
763
764 case OPT_WORKDIR:
765 kfree(config->workdir);
766 config->workdir = match_strdup(&args[0]);
767 if (!config->workdir)
768 return -ENOMEM;
769 break;
770
Miklos Szeredi8d3095f2015-10-12 17:11:44 +0200771 case OPT_DEFAULT_PERMISSIONS:
772 config->default_permissions = true;
773 break;
774
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200775 default:
hujianyangbead55e2015-01-15 13:17:36 +0800776 pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200777 return -EINVAL;
778 }
779 }
hujianyang71cbad72015-01-15 13:20:57 +0800780
781 /* Workdir is useless in non-upper mount */
782 if (!config->upperdir && config->workdir) {
783 pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
784 config->workdir);
785 kfree(config->workdir);
786 config->workdir = NULL;
787 }
788
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200789 return 0;
790}
791
792#define OVL_WORKDIR_NAME "work"
793
794static struct dentry *ovl_workdir_create(struct vfsmount *mnt,
795 struct dentry *dentry)
796{
797 struct inode *dir = dentry->d_inode;
798 struct dentry *work;
799 int err;
800 bool retried = false;
801
802 err = mnt_want_write(mnt);
803 if (err)
804 return ERR_PTR(err);
805
Al Viro59551022016-01-22 15:40:57 -0500806 inode_lock_nested(dir, I_MUTEX_PARENT);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200807retry:
808 work = lookup_one_len(OVL_WORKDIR_NAME, dentry,
809 strlen(OVL_WORKDIR_NAME));
810
811 if (!IS_ERR(work)) {
812 struct kstat stat = {
813 .mode = S_IFDIR | 0,
814 };
Miklos Szeredic11b9fd2016-09-01 11:11:59 +0200815 struct iattr attr = {
816 .ia_valid = ATTR_MODE,
817 .ia_mode = stat.mode,
818 };
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200819
820 if (work->d_inode) {
821 err = -EEXIST;
822 if (retried)
823 goto out_dput;
824
825 retried = true;
Miklos Szeredieea2fb42016-09-01 11:11:59 +0200826 ovl_workdir_cleanup(dir, mnt, work, 0);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200827 dput(work);
828 goto retry;
829 }
830
831 err = ovl_create_real(dir, work, &stat, NULL, NULL, true);
832 if (err)
833 goto out_dput;
Miklos Szeredic11b9fd2016-09-01 11:11:59 +0200834
Miklos Szeredicb348ed2016-10-04 14:40:44 +0200835 /*
836 * Try to remove POSIX ACL xattrs from workdir. We are good if:
837 *
838 * a) success (there was a POSIX ACL xattr and was removed)
839 * b) -ENODATA (there was no POSIX ACL xattr)
840 * c) -EOPNOTSUPP (POSIX ACL xattrs are not supported)
841 *
842 * There are various other error values that could effectively
843 * mean that the xattr doesn't exist (e.g. -ERANGE is returned
844 * if the xattr name is too long), but the set of filesystems
845 * allowed as upper are limited to "normal" ones, where checking
846 * for the above two errors is sufficient.
847 */
Miklos Szeredic11b9fd2016-09-01 11:11:59 +0200848 err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_DEFAULT);
Miklos Szeredie1ff3dd2016-09-05 13:55:20 +0200849 if (err && err != -ENODATA && err != -EOPNOTSUPP)
Miklos Szeredic11b9fd2016-09-01 11:11:59 +0200850 goto out_dput;
851
852 err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_ACCESS);
Miklos Szeredie1ff3dd2016-09-05 13:55:20 +0200853 if (err && err != -ENODATA && err != -EOPNOTSUPP)
Miklos Szeredic11b9fd2016-09-01 11:11:59 +0200854 goto out_dput;
855
856 /* Clear any inherited mode bits */
857 inode_lock(work->d_inode);
858 err = notify_change(work, &attr, NULL);
859 inode_unlock(work->d_inode);
860 if (err)
861 goto out_dput;
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200862 }
863out_unlock:
Al Viro59551022016-01-22 15:40:57 -0500864 inode_unlock(dir);
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200865 mnt_drop_write(mnt);
866
867 return work;
868
869out_dput:
870 dput(work);
871 work = ERR_PTR(err);
872 goto out_unlock;
873}
874
Miklos Szeredi91c77942014-11-20 16:40:00 +0100875static void ovl_unescape(char *s)
876{
877 char *d = s;
878
879 for (;; s++, d++) {
880 if (*s == '\\')
881 s++;
882 *d = *s;
883 if (!*s)
884 break;
885 }
886}
887
Miklos Szerediab508822014-12-13 00:59:49 +0100888static int ovl_mount_dir_noesc(const char *name, struct path *path)
889{
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +0100890 int err = -EINVAL;
Miklos Szerediab508822014-12-13 00:59:49 +0100891
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +0100892 if (!*name) {
893 pr_err("overlayfs: empty lowerdir\n");
894 goto out;
895 }
Miklos Szerediab508822014-12-13 00:59:49 +0100896 err = kern_path(name, LOOKUP_FOLLOW, path);
897 if (err) {
898 pr_err("overlayfs: failed to resolve '%s': %i\n", name, err);
899 goto out;
900 }
901 err = -EINVAL;
Miklos Szeredi7c03b5d2015-06-22 13:53:48 +0200902 if (ovl_dentry_weird(path->dentry)) {
Miklos Szerediab508822014-12-13 00:59:49 +0100903 pr_err("overlayfs: filesystem on '%s' not supported\n", name);
904 goto out_put;
905 }
906 if (!S_ISDIR(path->dentry->d_inode->i_mode)) {
907 pr_err("overlayfs: '%s' not a directory\n", name);
908 goto out_put;
909 }
910 return 0;
911
912out_put:
913 path_put(path);
914out:
915 return err;
916}
917
918static int ovl_mount_dir(const char *name, struct path *path)
919{
920 int err = -ENOMEM;
921 char *tmp = kstrdup(name, GFP_KERNEL);
922
923 if (tmp) {
924 ovl_unescape(tmp);
925 err = ovl_mount_dir_noesc(tmp, path);
Miklos Szeredi7c03b5d2015-06-22 13:53:48 +0200926
927 if (!err)
928 if (ovl_dentry_remote(path->dentry)) {
929 pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",
930 tmp);
931 path_put(path);
932 err = -EINVAL;
933 }
Miklos Szerediab508822014-12-13 00:59:49 +0100934 kfree(tmp);
935 }
936 return err;
937}
938
939static int ovl_lower_dir(const char *name, struct path *path, long *namelen,
Miklos Szeredi7c03b5d2015-06-22 13:53:48 +0200940 int *stack_depth, bool *remote)
Miklos Szerediab508822014-12-13 00:59:49 +0100941{
942 int err;
943 struct kstatfs statfs;
944
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +0100945 err = ovl_mount_dir_noesc(name, path);
Miklos Szerediab508822014-12-13 00:59:49 +0100946 if (err)
947 goto out;
948
949 err = vfs_statfs(path, &statfs);
950 if (err) {
951 pr_err("overlayfs: statfs failed on '%s'\n", name);
952 goto out_put;
953 }
954 *namelen = max(*namelen, statfs.f_namelen);
955 *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
956
Miklos Szeredi7c03b5d2015-06-22 13:53:48 +0200957 if (ovl_dentry_remote(path->dentry))
958 *remote = true;
959
Miklos Szerediab508822014-12-13 00:59:49 +0100960 return 0;
961
962out_put:
963 path_put(path);
964out:
965 return err;
966}
967
Miklos Szeredie9be9d52014-10-24 00:14:38 +0200968/* Workdir should not be subdir of upperdir and vice versa */
969static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
970{
971 bool ok = false;
972
973 if (workdir != upperdir) {
974 ok = (lock_rename(workdir, upperdir) == NULL);
975 unlock_rename(workdir, upperdir);
976 }
977 return ok;
978}
979
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +0100980static unsigned int ovl_split_lowerdirs(char *str)
981{
982 unsigned int ctr = 1;
983 char *s, *d;
984
985 for (s = d = str;; s++, d++) {
986 if (*s == '\\') {
987 s++;
988 } else if (*s == ':') {
989 *d = '\0';
990 ctr++;
991 continue;
992 }
993 *d = *s;
994 if (!*s)
995 break;
996 }
997 return ctr;
998}
999
Andreas Gruenbacher0c97be22016-08-22 16:36:49 +02001000static int __maybe_unused
Andreas Gruenbacher0eb45fc2016-08-22 17:52:55 +02001001ovl_posix_acl_xattr_get(const struct xattr_handler *handler,
1002 struct dentry *dentry, struct inode *inode,
1003 const char *name, void *buffer, size_t size)
1004{
1005 return ovl_xattr_get(dentry, handler->name, buffer, size);
1006}
1007
1008static int __maybe_unused
Andreas Gruenbacher0c97be22016-08-22 16:36:49 +02001009ovl_posix_acl_xattr_set(const struct xattr_handler *handler,
1010 struct dentry *dentry, struct inode *inode,
1011 const char *name, const void *value,
1012 size_t size, int flags)
Miklos Szeredid837a492016-07-29 12:05:24 +02001013{
1014 struct dentry *workdir = ovl_workdir(dentry);
1015 struct inode *realinode = ovl_inode_real(inode, NULL);
1016 struct posix_acl *acl = NULL;
1017 int err;
1018
1019 /* Check that everything is OK before copy-up */
1020 if (value) {
1021 acl = posix_acl_from_xattr(&init_user_ns, value, size);
1022 if (IS_ERR(acl))
1023 return PTR_ERR(acl);
1024 }
1025 err = -EOPNOTSUPP;
1026 if (!IS_POSIXACL(d_inode(workdir)))
1027 goto out_acl_release;
1028 if (!realinode->i_op->set_acl)
1029 goto out_acl_release;
1030 if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) {
1031 err = acl ? -EACCES : 0;
1032 goto out_acl_release;
1033 }
1034 err = -EPERM;
1035 if (!inode_owner_or_capable(inode))
1036 goto out_acl_release;
1037
1038 posix_acl_release(acl);
1039
Miklos Szeredifd3220d2016-10-31 14:42:14 +01001040 /*
1041 * Check if sgid bit needs to be cleared (actual setacl operation will
1042 * be done with mounter's capabilities and so that won't do it for us).
1043 */
1044 if (unlikely(inode->i_mode & S_ISGID) &&
1045 handler->flags == ACL_TYPE_ACCESS &&
1046 !in_group_p(inode->i_gid) &&
1047 !capable_wrt_inode_uidgid(inode, CAP_FSETID)) {
1048 struct iattr iattr = { .ia_valid = ATTR_KILL_SGID };
1049
1050 err = ovl_setattr(dentry, &iattr);
1051 if (err)
1052 return err;
1053 }
1054
Miklos Szeredice315132016-09-01 11:12:00 +02001055 err = ovl_xattr_set(dentry, handler->name, value, size, flags);
1056 if (!err)
1057 ovl_copyattr(ovl_inode_real(inode, NULL), inode);
1058
1059 return err;
Miklos Szeredid837a492016-07-29 12:05:24 +02001060
1061out_acl_release:
1062 posix_acl_release(acl);
1063 return err;
1064}
1065
Andreas Gruenbacher0eb45fc2016-08-22 17:52:55 +02001066static int ovl_own_xattr_get(const struct xattr_handler *handler,
1067 struct dentry *dentry, struct inode *inode,
1068 const char *name, void *buffer, size_t size)
1069{
1070 return -EPERM;
1071}
1072
Miklos Szeredid837a492016-07-29 12:05:24 +02001073static int ovl_own_xattr_set(const struct xattr_handler *handler,
1074 struct dentry *dentry, struct inode *inode,
1075 const char *name, const void *value,
1076 size_t size, int flags)
1077{
1078 return -EPERM;
1079}
1080
Andreas Gruenbacher0eb45fc2016-08-22 17:52:55 +02001081static int ovl_other_xattr_get(const struct xattr_handler *handler,
1082 struct dentry *dentry, struct inode *inode,
1083 const char *name, void *buffer, size_t size)
1084{
1085 return ovl_xattr_get(dentry, name, buffer, size);
1086}
1087
Andreas Gruenbacher0e585cc2016-08-22 17:22:11 +02001088static int ovl_other_xattr_set(const struct xattr_handler *handler,
1089 struct dentry *dentry, struct inode *inode,
1090 const char *name, const void *value,
1091 size_t size, int flags)
1092{
1093 return ovl_xattr_set(dentry, name, value, size, flags);
1094}
1095
Andreas Gruenbacher0c97be22016-08-22 16:36:49 +02001096static const struct xattr_handler __maybe_unused
1097ovl_posix_acl_access_xattr_handler = {
Miklos Szeredid837a492016-07-29 12:05:24 +02001098 .name = XATTR_NAME_POSIX_ACL_ACCESS,
1099 .flags = ACL_TYPE_ACCESS,
Andreas Gruenbacher0eb45fc2016-08-22 17:52:55 +02001100 .get = ovl_posix_acl_xattr_get,
Miklos Szeredid837a492016-07-29 12:05:24 +02001101 .set = ovl_posix_acl_xattr_set,
1102};
1103
Andreas Gruenbacher0c97be22016-08-22 16:36:49 +02001104static const struct xattr_handler __maybe_unused
1105ovl_posix_acl_default_xattr_handler = {
Miklos Szeredid837a492016-07-29 12:05:24 +02001106 .name = XATTR_NAME_POSIX_ACL_DEFAULT,
1107 .flags = ACL_TYPE_DEFAULT,
Andreas Gruenbacher0eb45fc2016-08-22 17:52:55 +02001108 .get = ovl_posix_acl_xattr_get,
Miklos Szeredid837a492016-07-29 12:05:24 +02001109 .set = ovl_posix_acl_xattr_set,
1110};
1111
1112static const struct xattr_handler ovl_own_xattr_handler = {
1113 .prefix = OVL_XATTR_PREFIX,
Andreas Gruenbacher0eb45fc2016-08-22 17:52:55 +02001114 .get = ovl_own_xattr_get,
Miklos Szeredid837a492016-07-29 12:05:24 +02001115 .set = ovl_own_xattr_set,
1116};
1117
1118static const struct xattr_handler ovl_other_xattr_handler = {
1119 .prefix = "", /* catch all */
Andreas Gruenbacher0eb45fc2016-08-22 17:52:55 +02001120 .get = ovl_other_xattr_get,
Miklos Szeredid837a492016-07-29 12:05:24 +02001121 .set = ovl_other_xattr_set,
1122};
1123
1124static const struct xattr_handler *ovl_xattr_handlers[] = {
Andreas Gruenbacher0c97be22016-08-22 16:36:49 +02001125#ifdef CONFIG_FS_POSIX_ACL
Miklos Szeredid837a492016-07-29 12:05:24 +02001126 &ovl_posix_acl_access_xattr_handler,
1127 &ovl_posix_acl_default_xattr_handler,
Andreas Gruenbacher0c97be22016-08-22 16:36:49 +02001128#endif
Miklos Szeredid837a492016-07-29 12:05:24 +02001129 &ovl_own_xattr_handler,
1130 &ovl_other_xattr_handler,
1131 NULL
1132};
1133
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001134static int ovl_fill_super(struct super_block *sb, void *data, int silent)
1135{
Miklos Szeredi53a08cb2014-12-13 00:59:51 +01001136 struct path upperpath = { NULL, NULL };
1137 struct path workpath = { NULL, NULL };
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001138 struct dentry *root_dentry;
Miklos Szeredi39b681f2016-07-29 12:05:24 +02001139 struct inode *realinode;
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001140 struct ovl_entry *oe;
1141 struct ovl_fs *ufs;
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +01001142 struct path *stack = NULL;
1143 char *lowertmp;
1144 char *lower;
1145 unsigned int numlower;
1146 unsigned int stacklen = 0;
Miklos Szeredidd662662014-12-13 00:59:43 +01001147 unsigned int i;
Miklos Szeredi7c03b5d2015-06-22 13:53:48 +02001148 bool remote = false;
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001149 int err;
1150
Erez Zadokf45827e82014-10-24 00:14:38 +02001151 err = -ENOMEM;
1152 ufs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL);
1153 if (!ufs)
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001154 goto out;
1155
Erez Zadokf45827e82014-10-24 00:14:38 +02001156 err = ovl_parse_opt((char *) data, &ufs->config);
1157 if (err)
1158 goto out_free_config;
1159
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001160 err = -EINVAL;
Miklos Szeredi53a08cb2014-12-13 00:59:51 +01001161 if (!ufs->config.lowerdir) {
Konstantin Khlebnikov07f2af72015-06-29 20:18:56 +03001162 if (!silent)
1163 pr_err("overlayfs: missing 'lowerdir'\n");
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001164 goto out_free_config;
1165 }
1166
Miklos Szeredi53a08cb2014-12-13 00:59:51 +01001167 sb->s_stack_depth = 0;
Miklos Szeredicf9a6782015-12-11 16:30:49 +01001168 sb->s_maxbytes = MAX_LFS_FILESIZE;
Miklos Szeredi53a08cb2014-12-13 00:59:51 +01001169 if (ufs->config.upperdir) {
Miklos Szeredi53a08cb2014-12-13 00:59:51 +01001170 if (!ufs->config.workdir) {
1171 pr_err("overlayfs: missing 'workdir'\n");
1172 goto out_free_config;
1173 }
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001174
Miklos Szeredi53a08cb2014-12-13 00:59:51 +01001175 err = ovl_mount_dir(ufs->config.upperdir, &upperpath);
1176 if (err)
1177 goto out_free_config;
Miklos Szeredi3b7a9a22014-12-13 00:59:48 +01001178
hujianyang71cbad72015-01-15 13:20:57 +08001179 /* Upper fs should not be r/o */
1180 if (upperpath.mnt->mnt_sb->s_flags & MS_RDONLY) {
1181 pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n");
1182 err = -EINVAL;
1183 goto out_put_upperpath;
1184 }
1185
Miklos Szeredi53a08cb2014-12-13 00:59:51 +01001186 err = ovl_mount_dir(ufs->config.workdir, &workpath);
1187 if (err)
1188 goto out_put_upperpath;
1189
hujianyang2f83fd82015-01-06 12:52:13 +08001190 err = -EINVAL;
Miklos Szeredi53a08cb2014-12-13 00:59:51 +01001191 if (upperpath.mnt != workpath.mnt) {
1192 pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
1193 goto out_put_workpath;
1194 }
1195 if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) {
1196 pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
1197 goto out_put_workpath;
1198 }
1199 sb->s_stack_depth = upperpath.mnt->mnt_sb->s_stack_depth;
Miklos Szerediab508822014-12-13 00:59:49 +01001200 }
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +01001201 err = -ENOMEM;
1202 lowertmp = kstrdup(ufs->config.lowerdir, GFP_KERNEL);
1203 if (!lowertmp)
Miklos Szeredi3b7a9a22014-12-13 00:59:48 +01001204 goto out_put_workpath;
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001205
1206 err = -EINVAL;
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +01001207 stacklen = ovl_split_lowerdirs(lowertmp);
hujianyang6be45062015-01-15 13:19:21 +08001208 if (stacklen > OVL_MAX_STACK) {
Colin Ian Kingfd365702016-08-18 16:58:35 +01001209 pr_err("overlayfs: too many lower directories, limit is %d\n",
hujianyang6be45062015-01-15 13:19:21 +08001210 OVL_MAX_STACK);
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +01001211 goto out_free_lowertmp;
hujianyang6be45062015-01-15 13:19:21 +08001212 } else if (!ufs->config.upperdir && stacklen == 1) {
1213 pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n");
1214 goto out_free_lowertmp;
1215 }
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +01001216
1217 stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL);
1218 if (!stack)
1219 goto out_free_lowertmp;
1220
1221 lower = lowertmp;
1222 for (numlower = 0; numlower < stacklen; numlower++) {
1223 err = ovl_lower_dir(lower, &stack[numlower],
Miklos Szeredi7c03b5d2015-06-22 13:53:48 +02001224 &ufs->lower_namelen, &sb->s_stack_depth,
1225 &remote);
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +01001226 if (err)
1227 goto out_put_lowerpath;
1228
1229 lower = strchr(lower, '\0') + 1;
1230 }
1231
1232 err = -EINVAL;
Miklos Szerediab508822014-12-13 00:59:49 +01001233 sb->s_stack_depth++;
Miklos Szeredi69c433e2014-10-24 00:14:39 +02001234 if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
1235 pr_err("overlayfs: maximum fs stacking depth exceeded\n");
Miklos Szeredi3b7a9a22014-12-13 00:59:48 +01001236 goto out_put_lowerpath;
Miklos Szeredi69c433e2014-10-24 00:14:39 +02001237 }
1238
Miklos Szeredi53a08cb2014-12-13 00:59:51 +01001239 if (ufs->config.upperdir) {
1240 ufs->upper_mnt = clone_private_mount(&upperpath);
1241 err = PTR_ERR(ufs->upper_mnt);
1242 if (IS_ERR(ufs->upper_mnt)) {
1243 pr_err("overlayfs: failed to clone upperpath\n");
1244 goto out_put_lowerpath;
1245 }
Miklos Szeredid719e8f2016-07-29 12:05:23 +02001246 /* Don't inherit atime flags */
1247 ufs->upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME);
1248
1249 sb->s_time_gran = ufs->upper_mnt->mnt_sb->s_time_gran;
Miklos Szeredi3b7a9a22014-12-13 00:59:48 +01001250
Miklos Szeredi53a08cb2014-12-13 00:59:51 +01001251 ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry);
1252 err = PTR_ERR(ufs->workdir);
1253 if (IS_ERR(ufs->workdir)) {
Miklos Szeredicc6f67b2015-05-19 14:30:12 +02001254 pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n",
1255 ufs->config.workdir, OVL_WORKDIR_NAME, -err);
1256 sb->s_flags |= MS_RDONLY;
1257 ufs->workdir = NULL;
Miklos Szeredi53a08cb2014-12-13 00:59:51 +01001258 }
Vivek Goyal45aebea2016-02-22 09:28:34 -05001259
1260 /*
1261 * Upper should support d_type, else whiteouts are visible.
1262 * Given workdir and upper are on same fs, we can do
Vivek Goyal21765192016-05-20 09:04:26 -04001263 * iterate_dir() on workdir. This check requires successful
1264 * creation of workdir in previous step.
Vivek Goyal45aebea2016-02-22 09:28:34 -05001265 */
Vivek Goyal21765192016-05-20 09:04:26 -04001266 if (ufs->workdir) {
1267 err = ovl_check_d_type_supported(&workpath);
1268 if (err < 0)
1269 goto out_put_workdir;
Vivek Goyal45aebea2016-02-22 09:28:34 -05001270
Vivek Goyale7c0b592016-07-01 10:02:44 -04001271 /*
1272 * We allowed this configuration and don't want to
1273 * break users over kernel upgrade. So warn instead
1274 * of erroring out.
1275 */
1276 if (!err)
1277 pr_warn("overlayfs: upper fs needs to support d_type.\n");
Vivek Goyal45aebea2016-02-22 09:28:34 -05001278 }
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001279 }
1280
hujianyang2f83fd82015-01-06 12:52:13 +08001281 err = -ENOMEM;
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +01001282 ufs->lower_mnt = kcalloc(numlower, sizeof(struct vfsmount *), GFP_KERNEL);
Miklos Szeredidd662662014-12-13 00:59:43 +01001283 if (ufs->lower_mnt == NULL)
Miklos Szeredi3b7a9a22014-12-13 00:59:48 +01001284 goto out_put_workdir;
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +01001285 for (i = 0; i < numlower; i++) {
1286 struct vfsmount *mnt = clone_private_mount(&stack[i]);
Miklos Szeredidd662662014-12-13 00:59:43 +01001287
hujianyang2f83fd82015-01-06 12:52:13 +08001288 err = PTR_ERR(mnt);
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +01001289 if (IS_ERR(mnt)) {
1290 pr_err("overlayfs: failed to clone lowerpath\n");
1291 goto out_put_lower_mnt;
1292 }
1293 /*
1294 * Make lower_mnt R/O. That way fchmod/fchown on lower file
1295 * will fail instead of modifying lower fs.
1296 */
Miklos Szeredid719e8f2016-07-29 12:05:23 +02001297 mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME;
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +01001298
1299 ufs->lower_mnt[ufs->numlower] = mnt;
1300 ufs->numlower++;
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001301 }
1302
hujianyang71cbad72015-01-15 13:20:57 +08001303 /* If the upper fs is nonexistent, we mark overlayfs r/o too */
1304 if (!ufs->upper_mnt)
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001305 sb->s_flags |= MS_RDONLY;
1306
Miklos Szeredi7c03b5d2015-06-22 13:53:48 +02001307 if (remote)
1308 sb->s_d_op = &ovl_reval_dentry_operations;
1309 else
1310 sb->s_d_op = &ovl_dentry_operations;
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001311
Antonio Murdaca3fe6e522016-04-07 15:48:25 +02001312 ufs->creator_cred = prepare_creds();
1313 if (!ufs->creator_cred)
1314 goto out_put_lower_mnt;
1315
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001316 err = -ENOMEM;
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +01001317 oe = ovl_alloc_entry(numlower);
Miklos Szeredi3b7a9a22014-12-13 00:59:48 +01001318 if (!oe)
Antonio Murdaca3fe6e522016-04-07 15:48:25 +02001319 goto out_put_cred;
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001320
Vivek Goyal655042c2016-10-14 03:03:36 +02001321 sb->s_magic = OVERLAYFS_SUPER_MAGIC;
1322 sb->s_op = &ovl_super_operations;
1323 sb->s_xattr = ovl_xattr_handlers;
1324 sb->s_fs_info = ufs;
1325 sb->s_flags |= MS_POSIXACL | MS_NOREMOTELOCK;
1326
Miklos Szeredi39b681f2016-07-29 12:05:24 +02001327 root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR));
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001328 if (!root_dentry)
Miklos Szeredi3b7a9a22014-12-13 00:59:48 +01001329 goto out_free_oe;
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001330
1331 mntput(upperpath.mnt);
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +01001332 for (i = 0; i < numlower; i++)
1333 mntput(stack[i].mnt);
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001334 path_put(&workpath);
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +01001335 kfree(lowertmp);
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001336
1337 oe->__upperdentry = upperpath.dentry;
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +01001338 for (i = 0; i < numlower; i++) {
1339 oe->lowerstack[i].dentry = stack[i].dentry;
1340 oe->lowerstack[i].mnt = ufs->lower_mnt[i];
1341 }
Konstantin Khlebnikov0f955022015-08-24 15:57:18 +03001342 kfree(stack);
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001343
1344 root_dentry->d_fsdata = oe;
1345
Miklos Szeredi39b681f2016-07-29 12:05:24 +02001346 realinode = d_inode(ovl_dentry_real(root_dentry));
1347 ovl_inode_init(d_inode(root_dentry), realinode, !!upperpath.dentry);
1348 ovl_copyattr(realinode, d_inode(root_dentry));
Miklos Szeredied06e062015-12-09 16:11:59 +01001349
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001350 sb->s_root = root_dentry;
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001351
1352 return 0;
1353
Miklos Szeredi3b7a9a22014-12-13 00:59:48 +01001354out_free_oe:
1355 kfree(oe);
Antonio Murdaca3fe6e522016-04-07 15:48:25 +02001356out_put_cred:
1357 put_cred(ufs->creator_cred);
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001358out_put_lower_mnt:
Miklos Szeredidd662662014-12-13 00:59:43 +01001359 for (i = 0; i < ufs->numlower; i++)
1360 mntput(ufs->lower_mnt[i]);
1361 kfree(ufs->lower_mnt);
Miklos Szeredi3b7a9a22014-12-13 00:59:48 +01001362out_put_workdir:
1363 dput(ufs->workdir);
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001364 mntput(ufs->upper_mnt);
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001365out_put_lowerpath:
Miklos Szeredia78d9f0d2014-12-13 00:59:52 +01001366 for (i = 0; i < numlower; i++)
1367 path_put(&stack[i]);
1368 kfree(stack);
1369out_free_lowertmp:
1370 kfree(lowertmp);
Miklos Szeredi3b7a9a22014-12-13 00:59:48 +01001371out_put_workpath:
1372 path_put(&workpath);
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001373out_put_upperpath:
1374 path_put(&upperpath);
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001375out_free_config:
Erez Zadokf45827e82014-10-24 00:14:38 +02001376 kfree(ufs->config.lowerdir);
1377 kfree(ufs->config.upperdir);
1378 kfree(ufs->config.workdir);
1379 kfree(ufs);
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001380out:
1381 return err;
1382}
1383
1384static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags,
1385 const char *dev_name, void *raw_data)
1386{
1387 return mount_nodev(fs_type, flags, raw_data, ovl_fill_super);
1388}
1389
1390static struct file_system_type ovl_fs_type = {
1391 .owner = THIS_MODULE,
Miklos Szeredief94b182014-11-20 16:39:59 +01001392 .name = "overlay",
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001393 .mount = ovl_mount,
1394 .kill_sb = kill_anon_super,
1395};
Miklos Szeredief94b182014-11-20 16:39:59 +01001396MODULE_ALIAS_FS("overlay");
Miklos Szeredie9be9d52014-10-24 00:14:38 +02001397
1398static int __init ovl_init(void)
1399{
1400 return register_filesystem(&ovl_fs_type);
1401}
1402
1403static void __exit ovl_exit(void)
1404{
1405 unregister_filesystem(&ovl_fs_type);
1406}
1407
1408module_init(ovl_init);
1409module_exit(ovl_exit);