1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 *
4 * Copyright (C) 2011 Novell Inc.
5 */
6
7#include <linux/kernel.h>
8#include <linux/uuid.h>
9#include <linux/fs.h>
10#include <linux/fsverity.h>
11#include <linux/namei.h>
12#include <linux/posix_acl.h>
13#include <linux/posix_acl_xattr.h>
14#include "ovl_entry.h"
15
16#undef pr_fmt
17#define pr_fmt(fmt) "overlayfs: " fmt
18
19enum ovl_path_type {
20 __OVL_PATH_UPPER = (1 << 0),
21 __OVL_PATH_MERGE = (1 << 1),
22 __OVL_PATH_ORIGIN = (1 << 2),
23};
24
25#define OVL_TYPE_UPPER(type) ((type) & __OVL_PATH_UPPER)
26#define OVL_TYPE_MERGE(type) ((type) & __OVL_PATH_MERGE)
27#define OVL_TYPE_ORIGIN(type) ((type) & __OVL_PATH_ORIGIN)
28
29#define OVL_XATTR_NAMESPACE "overlay."
30#define OVL_XATTR_TRUSTED_PREFIX XATTR_TRUSTED_PREFIX OVL_XATTR_NAMESPACE
31#define OVL_XATTR_TRUSTED_PREFIX_LEN (sizeof(OVL_XATTR_TRUSTED_PREFIX) - 1)
32#define OVL_XATTR_USER_PREFIX XATTR_USER_PREFIX OVL_XATTR_NAMESPACE
33#define OVL_XATTR_USER_PREFIX_LEN (sizeof(OVL_XATTR_USER_PREFIX) - 1)
34
35#define OVL_XATTR_ESCAPE_PREFIX OVL_XATTR_NAMESPACE
36#define OVL_XATTR_ESCAPE_PREFIX_LEN (sizeof(OVL_XATTR_ESCAPE_PREFIX) - 1)
37#define OVL_XATTR_ESCAPE_TRUSTED_PREFIX OVL_XATTR_TRUSTED_PREFIX OVL_XATTR_ESCAPE_PREFIX
38#define OVL_XATTR_ESCAPE_TRUSTED_PREFIX_LEN (sizeof(OVL_XATTR_ESCAPE_TRUSTED_PREFIX) - 1)
39#define OVL_XATTR_ESCAPE_USER_PREFIX OVL_XATTR_USER_PREFIX OVL_XATTR_ESCAPE_PREFIX
40#define OVL_XATTR_ESCAPE_USER_PREFIX_LEN (sizeof(OVL_XATTR_ESCAPE_USER_PREFIX) - 1)
41
42enum ovl_xattr {
43 OVL_XATTR_OPAQUE,
44 OVL_XATTR_REDIRECT,
45 OVL_XATTR_ORIGIN,
46 OVL_XATTR_IMPURE,
47 OVL_XATTR_NLINK,
48 OVL_XATTR_UPPER,
49 OVL_XATTR_UUID,
50 OVL_XATTR_METACOPY,
51 OVL_XATTR_PROTATTR,
52 OVL_XATTR_XWHITEOUT,
53};
54
55enum ovl_inode_flag {
56 /* Pure upper dir that may contain non pure upper entries */
57 OVL_IMPURE,
58 /* Non-merge dir that may contain whiteout entries */
59 OVL_WHITEOUTS,
60 OVL_INDEX,
61 OVL_UPPERDATA,
62 /* Inode number will remain constant over copy up. */
63 OVL_CONST_INO,
64 OVL_HAS_DIGEST,
65 OVL_VERIFIED_DIGEST,
66};
67
68enum ovl_entry_flag {
69 OVL_E_UPPER_ALIAS,
70 OVL_E_OPAQUE,
71 OVL_E_CONNECTED,
72 /* Lower stack may contain xwhiteout entries */
73 OVL_E_XWHITEOUTS,
74};
75
76enum {
77 OVL_REDIRECT_OFF, /* "off" mode is never used. In effect */
78 OVL_REDIRECT_FOLLOW, /* ...it translates to either "follow" */
79 OVL_REDIRECT_NOFOLLOW, /* ...or "nofollow". */
80 OVL_REDIRECT_ON,
81};
82
83enum {
84 OVL_UUID_OFF,
85 OVL_UUID_NULL,
86 OVL_UUID_AUTO,
87 OVL_UUID_ON,
88};
89
90enum {
91 OVL_XINO_OFF,
92 OVL_XINO_AUTO,
93 OVL_XINO_ON,
94};
95
96enum {
97 OVL_VERITY_OFF,
98 OVL_VERITY_ON,
99 OVL_VERITY_REQUIRE,
100};
101
102/*
103 * The tuple (fh,uuid) is a universal unique identifier for a copy up origin,
104 * where:
105 * origin.fh - exported file handle of the lower file
106 * origin.uuid - uuid of the lower filesystem
107 */
108#define OVL_FH_VERSION 0
109#define OVL_FH_MAGIC 0xfb
110
111/* CPU byte order required for fid decoding: */
112#define OVL_FH_FLAG_BIG_ENDIAN (1 << 0)
113#define OVL_FH_FLAG_ANY_ENDIAN (1 << 1)
114/* Is the real inode encoded in fid an upper inode? */
115#define OVL_FH_FLAG_PATH_UPPER (1 << 2)
116
117#define OVL_FH_FLAG_ALL (OVL_FH_FLAG_BIG_ENDIAN | OVL_FH_FLAG_ANY_ENDIAN | \
118 OVL_FH_FLAG_PATH_UPPER)
119
120#if defined(__LITTLE_ENDIAN)
121#define OVL_FH_FLAG_CPU_ENDIAN 0
122#elif defined(__BIG_ENDIAN)
123#define OVL_FH_FLAG_CPU_ENDIAN OVL_FH_FLAG_BIG_ENDIAN
124#else
125#error Endianness not defined
126#endif
127
128/* The type used to be returned by overlay exportfs for misaligned fid */
129#define OVL_FILEID_V0 0xfb
130/* The type returned by overlay exportfs for 32bit aligned fid */
131#define OVL_FILEID_V1 0xf8
132
133/* On-disk format for "origin" file handle */
134struct ovl_fb {
135 u8 version; /* 0 */
136 u8 magic; /* 0xfb */
137 u8 len; /* size of this header + size of fid */
138 u8 flags; /* OVL_FH_FLAG_* */
139 u8 type; /* fid_type of fid */
140 uuid_t uuid; /* uuid of filesystem */
141 u32 fid[]; /* file identifier should be 32bit aligned in-memory */
142} __packed;
143
144/* In-memory and on-wire format for overlay file handle */
145struct ovl_fh {
146 u8 padding[3]; /* make sure fb.fid is 32bit aligned */
147 union {
148 struct ovl_fb fb;
149 DECLARE_FLEX_ARRAY(u8, buf);
150 };
151} __packed;
152
153#define OVL_FH_WIRE_OFFSET offsetof(struct ovl_fh, fb)
154#define OVL_FH_LEN(fh) (OVL_FH_WIRE_OFFSET + (fh)->fb.len)
155#define OVL_FH_FID_OFFSET (OVL_FH_WIRE_OFFSET + \
156 offsetof(struct ovl_fb, fid))
157
158/* On-disk format for "metacopy" xattr (if non-zero size) */
159struct ovl_metacopy {
160 u8 version; /* 0 */
161 u8 len; /* size of this header + used digest bytes */
162 u8 flags;
163 u8 digest_algo; /* FS_VERITY_HASH_ALG_* constant, 0 for no digest */
164 u8 digest[FS_VERITY_MAX_DIGEST_SIZE]; /* Only the used part on disk */
165} __packed;
166
167#define OVL_METACOPY_MAX_SIZE (sizeof(struct ovl_metacopy))
168#define OVL_METACOPY_MIN_SIZE (OVL_METACOPY_MAX_SIZE - FS_VERITY_MAX_DIGEST_SIZE)
169#define OVL_METACOPY_INIT { 0, OVL_METACOPY_MIN_SIZE }
170
171static inline int ovl_metadata_digest_size(const struct ovl_metacopy *metacopy)
172{
173 if (metacopy->len < OVL_METACOPY_MIN_SIZE)
174 return 0;
175 return (int)metacopy->len - OVL_METACOPY_MIN_SIZE;
176}
177
178extern const char *const ovl_xattr_table[][2];
179static inline const char *ovl_xattr(struct ovl_fs *ofs, enum ovl_xattr ox)
180{
181 return ovl_xattr_table[ox][ofs->config.userxattr];
182}
183
184/*
185 * When changing ownership of an upper object map the intended ownership
186 * according to the upper layer's idmapping. When an upper mount idmaps files
187 * that are stored on-disk as owned by id 1001 to id 1000 this means stat on
188 * this object will report it as being owned by id 1000 when calling stat via
189 * the upper mount.
190 * In order to change ownership of an object so stat reports id 1000 when
191 * called on an idmapped upper mount the value written to disk - i.e., the
192 * value stored in ia_*id - must 1001. The mount mapping helper will thus take
193 * care to map 1000 to 1001.
194 * The mnt idmapping helpers are nops if the upper layer isn't idmapped.
195 */
196static inline int ovl_do_notify_change(struct ovl_fs *ofs,
197 struct dentry *upperdentry,
198 struct iattr *attr)
199{
200 return notify_change(ovl_upper_mnt_idmap(ofs), upperdentry, attr, NULL);
201}
202
203static inline int ovl_do_rmdir(struct ovl_fs *ofs,
204 struct inode *dir, struct dentry *dentry)
205{
206 int err = vfs_rmdir(ovl_upper_mnt_idmap(ofs), dir, dentry);
207
208 pr_debug("rmdir(%pd2) = %i\n", dentry, err);
209 return err;
210}
211
212static inline int ovl_do_unlink(struct ovl_fs *ofs, struct inode *dir,
213 struct dentry *dentry)
214{
215 int err = vfs_unlink(ovl_upper_mnt_idmap(ofs), dir, dentry, NULL);
216
217 pr_debug("unlink(%pd2) = %i\n", dentry, err);
218 return err;
219}
220
221static inline int ovl_do_link(struct ovl_fs *ofs, struct dentry *old_dentry,
222 struct inode *dir, struct dentry *new_dentry)
223{
224 int err = vfs_link(old_dentry, ovl_upper_mnt_idmap(ofs), dir,
225 new_dentry, NULL);
226
227 pr_debug("link(%pd2, %pd2) = %i\n", old_dentry, new_dentry, err);
228 return err;
229}
230
231static inline int ovl_do_create(struct ovl_fs *ofs,
232 struct inode *dir, struct dentry *dentry,
233 umode_t mode)
234{
235 int err = vfs_create(ovl_upper_mnt_idmap(ofs), dir, dentry, mode, true);
236
237 pr_debug("create(%pd2, 0%o) = %i\n", dentry, mode, err);
238 return err;
239}
240
241static inline int ovl_do_mkdir(struct ovl_fs *ofs,
242 struct inode *dir, struct dentry *dentry,
243 umode_t mode)
244{
245 int err = vfs_mkdir(ovl_upper_mnt_idmap(ofs), dir, dentry, mode);
246 pr_debug("mkdir(%pd2, 0%o) = %i\n", dentry, mode, err);
247 return err;
248}
249
250static inline int ovl_do_mknod(struct ovl_fs *ofs,
251 struct inode *dir, struct dentry *dentry,
252 umode_t mode, dev_t dev)
253{
254 int err = vfs_mknod(ovl_upper_mnt_idmap(ofs), dir, dentry, mode, dev);
255
256 pr_debug("mknod(%pd2, 0%o, 0%o) = %i\n", dentry, mode, dev, err);
257 return err;
258}
259
260static inline int ovl_do_symlink(struct ovl_fs *ofs,
261 struct inode *dir, struct dentry *dentry,
262 const char *oldname)
263{
264 int err = vfs_symlink(ovl_upper_mnt_idmap(ofs), dir, dentry, oldname);
265
266 pr_debug("symlink(\"%s\", %pd2) = %i\n", oldname, dentry, err);
267 return err;
268}
269
270static inline ssize_t ovl_do_getxattr(const struct path *path, const char *name,
271 void *value, size_t size)
272{
273 int err, len;
274
275 WARN_ON(path->dentry->d_sb != path->mnt->mnt_sb);
276
277 err = vfs_getxattr(mnt_idmap(mnt: path->mnt), path->dentry,
278 name, value, size);
279 len = (value && err > 0) ? err : 0;
280
281 pr_debug("getxattr(%pd2, \"%s\", \"%*pE\", %zu, 0) = %i\n",
282 path->dentry, name, min(len, 48), value, size, err);
283 return err;
284}
285
286static inline ssize_t ovl_getxattr_upper(struct ovl_fs *ofs,
287 struct dentry *upperdentry,
288 enum ovl_xattr ox, void *value,
289 size_t size)
290{
291 struct path upperpath = {
292 .dentry = upperdentry,
293 .mnt = ovl_upper_mnt(ofs),
294 };
295
296 return ovl_do_getxattr(path: &upperpath, name: ovl_xattr(ofs, ox), value, size);
297}
298
299static inline ssize_t ovl_path_getxattr(struct ovl_fs *ofs,
300 const struct path *path,
301 enum ovl_xattr ox, void *value,
302 size_t size)
303{
304 return ovl_do_getxattr(path, name: ovl_xattr(ofs, ox), value, size);
305}
306
307static inline int ovl_do_setxattr(struct ovl_fs *ofs, struct dentry *dentry,
308 const char *name, const void *value,
309 size_t size, int flags)
310{
311 int err = vfs_setxattr(ovl_upper_mnt_idmap(ofs), dentry, name,
312 value, size, flags);
313
314 pr_debug("setxattr(%pd2, \"%s\", \"%*pE\", %zu, %d) = %i\n",
315 dentry, name, min((int)size, 48), value, size, flags, err);
316 return err;
317}
318
319static inline int ovl_setxattr(struct ovl_fs *ofs, struct dentry *dentry,
320 enum ovl_xattr ox, const void *value,
321 size_t size)
322{
323 return ovl_do_setxattr(ofs, dentry, name: ovl_xattr(ofs, ox), value, size, flags: 0);
324}
325
326static inline int ovl_do_removexattr(struct ovl_fs *ofs, struct dentry *dentry,
327 const char *name)
328{
329 int err = vfs_removexattr(ovl_upper_mnt_idmap(ofs), dentry, name);
330 pr_debug("removexattr(%pd2, \"%s\") = %i\n", dentry, name, err);
331 return err;
332}
333
334static inline int ovl_removexattr(struct ovl_fs *ofs, struct dentry *dentry,
335 enum ovl_xattr ox)
336{
337 return ovl_do_removexattr(ofs, dentry, name: ovl_xattr(ofs, ox));
338}
339
340static inline int ovl_do_set_acl(struct ovl_fs *ofs, struct dentry *dentry,
341 const char *acl_name, struct posix_acl *acl)
342{
343 return vfs_set_acl(idmap: ovl_upper_mnt_idmap(ofs), dentry, acl_name, kacl: acl);
344}
345
346static inline int ovl_do_remove_acl(struct ovl_fs *ofs, struct dentry *dentry,
347 const char *acl_name)
348{
349 return vfs_remove_acl(idmap: ovl_upper_mnt_idmap(ofs), dentry, acl_name);
350}
351
352static inline int ovl_do_rename(struct ovl_fs *ofs, struct inode *olddir,
353 struct dentry *olddentry, struct inode *newdir,
354 struct dentry *newdentry, unsigned int flags)
355{
356 int err;
357 struct renamedata rd = {
358 .old_mnt_idmap = ovl_upper_mnt_idmap(ofs),
359 .old_dir = olddir,
360 .old_dentry = olddentry,
361 .new_mnt_idmap = ovl_upper_mnt_idmap(ofs),
362 .new_dir = newdir,
363 .new_dentry = newdentry,
364 .flags = flags,
365 };
366
367 pr_debug("rename(%pd2, %pd2, 0x%x)\n", olddentry, newdentry, flags);
368 err = vfs_rename(&rd);
369 if (err) {
370 pr_debug("...rename(%pd2, %pd2, ...) = %i\n",
371 olddentry, newdentry, err);
372 }
373 return err;
374}
375
376static inline int ovl_do_whiteout(struct ovl_fs *ofs,
377 struct inode *dir, struct dentry *dentry)
378{
379 int err = vfs_whiteout(idmap: ovl_upper_mnt_idmap(ofs), dir, dentry);
380 pr_debug("whiteout(%pd2) = %i\n", dentry, err);
381 return err;
382}
383
384static inline struct file *ovl_do_tmpfile(struct ovl_fs *ofs,
385 struct dentry *dentry, umode_t mode)
386{
387 struct path path = { .mnt = ovl_upper_mnt(ofs), .dentry = dentry };
388 struct file *file = kernel_tmpfile_open(idmap: ovl_upper_mnt_idmap(ofs), parentpath: &path,
389 mode, O_LARGEFILE | O_WRONLY,
390 current_cred());
391 int err = PTR_ERR_OR_ZERO(ptr: file);
392
393 pr_debug("tmpfile(%pd2, 0%o) = %i\n", dentry, mode, err);
394 return file;
395}
396
397static inline struct dentry *ovl_lookup_upper(struct ovl_fs *ofs,
398 const char *name,
399 struct dentry *base, int len)
400{
401 return lookup_one(ovl_upper_mnt_idmap(ofs), name, base, len);
402}
403
404static inline bool ovl_open_flags_need_copy_up(int flags)
405{
406 if (!flags)
407 return false;
408
409 return ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC));
410}
411
412static inline int ovl_do_getattr(const struct path *path, struct kstat *stat,
413 u32 request_mask, unsigned int flags)
414{
415 if (flags & AT_GETATTR_NOSEC)
416 return vfs_getattr_nosec(path, stat, request_mask, flags);
417 return vfs_getattr(path, stat, request_mask, flags);
418}
419
420/* util.c */
421int ovl_get_write_access(struct dentry *dentry);
422void ovl_put_write_access(struct dentry *dentry);
423void ovl_start_write(struct dentry *dentry);
424void ovl_end_write(struct dentry *dentry);
425int ovl_want_write(struct dentry *dentry);
426void ovl_drop_write(struct dentry *dentry);
427struct dentry *ovl_workdir(struct dentry *dentry);
428const struct cred *ovl_override_creds(struct super_block *sb);
429
430static inline const struct cred *ovl_creds(struct super_block *sb)
431{
432 return OVL_FS(sb)->creator_cred;
433}
434
435int ovl_can_decode_fh(struct super_block *sb);
436struct dentry *ovl_indexdir(struct super_block *sb);
437bool ovl_index_all(struct super_block *sb);
438bool ovl_verify_lower(struct super_block *sb);
439struct ovl_path *ovl_stack_alloc(unsigned int n);
440void ovl_stack_cpy(struct ovl_path *dst, struct ovl_path *src, unsigned int n);
441void ovl_stack_put(struct ovl_path *stack, unsigned int n);
442void ovl_stack_free(struct ovl_path *stack, unsigned int n);
443struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
444void ovl_free_entry(struct ovl_entry *oe);
445bool ovl_dentry_remote(struct dentry *dentry);
446void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *realdentry);
447void ovl_dentry_init_reval(struct dentry *dentry, struct dentry *upperdentry,
448 struct ovl_entry *oe);
449void ovl_dentry_init_flags(struct dentry *dentry, struct dentry *upperdentry,
450 struct ovl_entry *oe, unsigned int mask);
451bool ovl_dentry_weird(struct dentry *dentry);
452enum ovl_path_type ovl_path_type(struct dentry *dentry);
453void ovl_path_upper(struct dentry *dentry, struct path *path);
454void ovl_path_lower(struct dentry *dentry, struct path *path);
455void ovl_path_lowerdata(struct dentry *dentry, struct path *path);
456struct inode *ovl_i_path_real(struct inode *inode, struct path *path);
457enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
458enum ovl_path_type ovl_path_realdata(struct dentry *dentry, struct path *path);
459struct dentry *ovl_dentry_upper(struct dentry *dentry);
460struct dentry *ovl_dentry_lower(struct dentry *dentry);
461struct dentry *ovl_dentry_lowerdata(struct dentry *dentry);
462int ovl_dentry_set_lowerdata(struct dentry *dentry, struct ovl_path *datapath);
463const struct ovl_layer *ovl_i_layer_lower(struct inode *inode);
464const struct ovl_layer *ovl_layer_lower(struct dentry *dentry);
465struct dentry *ovl_dentry_real(struct dentry *dentry);
466struct dentry *ovl_i_dentry_upper(struct inode *inode);
467struct inode *ovl_inode_upper(struct inode *inode);
468struct inode *ovl_inode_lower(struct inode *inode);
469struct inode *ovl_inode_lowerdata(struct inode *inode);
470struct inode *ovl_inode_real(struct inode *inode);
471struct inode *ovl_inode_realdata(struct inode *inode);
472const char *ovl_lowerdata_redirect(struct inode *inode);
473struct ovl_dir_cache *ovl_dir_cache(struct inode *inode);
474void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache);
475void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry);
476void ovl_dentry_clear_flag(unsigned long flag, struct dentry *dentry);
477bool ovl_dentry_test_flag(unsigned long flag, struct dentry *dentry);
478bool ovl_dentry_is_opaque(struct dentry *dentry);
479bool ovl_dentry_is_whiteout(struct dentry *dentry);
480void ovl_dentry_set_opaque(struct dentry *dentry);
481bool ovl_dentry_has_xwhiteouts(struct dentry *dentry);
482void ovl_dentry_set_xwhiteouts(struct dentry *dentry);
483void ovl_layer_set_xwhiteouts(struct ovl_fs *ofs,
484 const struct ovl_layer *layer);
485bool ovl_dentry_has_upper_alias(struct dentry *dentry);
486void ovl_dentry_set_upper_alias(struct dentry *dentry);
487bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags);
488bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags);
489bool ovl_has_upperdata(struct inode *inode);
490void ovl_set_upperdata(struct inode *inode);
491const char *ovl_dentry_get_redirect(struct dentry *dentry);
492void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect);
493void ovl_inode_update(struct inode *inode, struct dentry *upperdentry);
494void ovl_dir_modified(struct dentry *dentry, bool impurity);
495u64 ovl_inode_version_get(struct inode *inode);
496bool ovl_is_whiteout(struct dentry *dentry);
497bool ovl_path_is_whiteout(struct ovl_fs *ofs, const struct path *path);
498struct file *ovl_path_open(const struct path *path, int flags);
499int ovl_copy_up_start(struct dentry *dentry, int flags);
500void ovl_copy_up_end(struct dentry *dentry);
501bool ovl_already_copied_up(struct dentry *dentry, int flags);
502char ovl_get_dir_xattr_val(struct ovl_fs *ofs, const struct path *path,
503 enum ovl_xattr ox);
504bool ovl_path_check_origin_xattr(struct ovl_fs *ofs, const struct path *path);
505bool ovl_path_check_xwhiteout_xattr(struct ovl_fs *ofs, const struct path *path);
506bool ovl_init_uuid_xattr(struct super_block *sb, struct ovl_fs *ofs,
507 const struct path *upperpath);
508
509static inline bool ovl_upper_is_whiteout(struct ovl_fs *ofs,
510 struct dentry *upperdentry)
511{
512 struct path upperpath = {
513 .dentry = upperdentry,
514 .mnt = ovl_upper_mnt(ofs),
515 };
516 return ovl_path_is_whiteout(ofs, path: &upperpath);
517}
518
519static inline bool ovl_check_origin_xattr(struct ovl_fs *ofs,
520 struct dentry *upperdentry)
521{
522 struct path upperpath = {
523 .dentry = upperdentry,
524 .mnt = ovl_upper_mnt(ofs),
525 };
526 return ovl_path_check_origin_xattr(ofs, path: &upperpath);
527}
528
529int ovl_check_setxattr(struct ovl_fs *ofs, struct dentry *upperdentry,
530 enum ovl_xattr ox, const void *value, size_t size,
531 int xerr);
532int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry);
533bool ovl_inuse_trylock(struct dentry *dentry);
534void ovl_inuse_unlock(struct dentry *dentry);
535bool ovl_is_inuse(struct dentry *dentry);
536bool ovl_need_index(struct dentry *dentry);
537int ovl_nlink_start(struct dentry *dentry);
538void ovl_nlink_end(struct dentry *dentry);
539int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir);
540int ovl_check_metacopy_xattr(struct ovl_fs *ofs, const struct path *path,
541 struct ovl_metacopy *data);
542int ovl_set_metacopy_xattr(struct ovl_fs *ofs, struct dentry *d,
543 struct ovl_metacopy *metacopy);
544bool ovl_is_metacopy_dentry(struct dentry *dentry);
545char *ovl_get_redirect_xattr(struct ovl_fs *ofs, const struct path *path, int padding);
546int ovl_ensure_verity_loaded(struct path *path);
547int ovl_get_verity_xattr(struct ovl_fs *ofs, const struct path *path,
548 u8 *digest_buf, int *buf_length);
549int ovl_validate_verity(struct ovl_fs *ofs,
550 struct path *metapath,
551 struct path *datapath);
552int ovl_get_verity_digest(struct ovl_fs *ofs, struct path *src,
553 struct ovl_metacopy *metacopy);
554int ovl_sync_status(struct ovl_fs *ofs);
555
556static inline void ovl_set_flag(unsigned long flag, struct inode *inode)
557{
558 set_bit(nr: flag, addr: &OVL_I(inode)->flags);
559}
560
561static inline void ovl_clear_flag(unsigned long flag, struct inode *inode)
562{
563 clear_bit(nr: flag, addr: &OVL_I(inode)->flags);
564}
565
566static inline bool ovl_test_flag(unsigned long flag, struct inode *inode)
567{
568 return test_bit(flag, &OVL_I(inode)->flags);
569}
570
571static inline bool ovl_is_impuredir(struct super_block *sb,
572 struct dentry *upperdentry)
573{
574 struct ovl_fs *ofs = OVL_FS(sb);
575 struct path upperpath = {
576 .dentry = upperdentry,
577 .mnt = ovl_upper_mnt(ofs),
578 };
579
580 return ovl_get_dir_xattr_val(ofs, path: &upperpath, ox: OVL_XATTR_IMPURE) == 'y';
581}
582
583static inline char ovl_get_opaquedir_val(struct ovl_fs *ofs,
584 const struct path *path)
585{
586 return ovl_get_dir_xattr_val(ofs, path, ox: OVL_XATTR_OPAQUE);
587}
588
589static inline bool ovl_redirect_follow(struct ovl_fs *ofs)
590{
591 return ofs->config.redirect_mode != OVL_REDIRECT_NOFOLLOW;
592}
593
594static inline bool ovl_redirect_dir(struct ovl_fs *ofs)
595{
596 return ofs->config.redirect_mode == OVL_REDIRECT_ON;
597}
598
599static inline bool ovl_origin_uuid(struct ovl_fs *ofs)
600{
601 return ofs->config.uuid != OVL_UUID_OFF;
602}
603
604static inline bool ovl_has_fsid(struct ovl_fs *ofs)
605{
606 return ofs->config.uuid == OVL_UUID_ON ||
607 ofs->config.uuid == OVL_UUID_AUTO;
608}
609
610/*
611 * With xino=auto, we do best effort to keep all inodes on same st_dev and
612 * d_ino consistent with st_ino.
613 * With xino=on, we do the same effort but we warn if we failed.
614 */
615static inline bool ovl_xino_warn(struct ovl_fs *ofs)
616{
617 return ofs->config.xino == OVL_XINO_ON;
618}
619
620/*
621 * To avoid regressions in existing setups with overlay lower offline changes,
622 * we allow lower changes only if none of the new features are used.
623 */
624static inline bool ovl_allow_offline_changes(struct ovl_fs *ofs)
625{
626 return (!ofs->config.index && !ofs->config.metacopy &&
627 !ovl_redirect_dir(ofs) && !ovl_xino_warn(ofs));
628}
629
630/* All layers on same fs? */
631static inline bool ovl_same_fs(struct ovl_fs *ofs)
632{
633 return ofs->xino_mode == 0;
634}
635
636/* All overlay inodes have same st_dev? */
637static inline bool ovl_same_dev(struct ovl_fs *ofs)
638{
639 return ofs->xino_mode >= 0;
640}
641
642static inline unsigned int ovl_xino_bits(struct ovl_fs *ofs)
643{
644 return ovl_same_dev(ofs) ? ofs->xino_mode : 0;
645}
646
647static inline void ovl_inode_lock(struct inode *inode)
648{
649 mutex_lock(&OVL_I(inode)->lock);
650}
651
652static inline int ovl_inode_lock_interruptible(struct inode *inode)
653{
654 return mutex_lock_interruptible(&OVL_I(inode)->lock);
655}
656
657static inline void ovl_inode_unlock(struct inode *inode)
658{
659 mutex_unlock(lock: &OVL_I(inode)->lock);
660}
661
662
663/* namei.c */
664int ovl_check_fb_len(struct ovl_fb *fb, int fb_len);
665
666static inline int ovl_check_fh_len(struct ovl_fh *fh, int fh_len)
667{
668 if (fh_len < sizeof(struct ovl_fh))
669 return -EINVAL;
670
671 return ovl_check_fb_len(fb: &fh->fb, fb_len: fh_len - OVL_FH_WIRE_OFFSET);
672}
673
674struct dentry *ovl_decode_real_fh(struct ovl_fs *ofs, struct ovl_fh *fh,
675 struct vfsmount *mnt, bool connected);
676int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
677 struct dentry *upperdentry, struct ovl_path **stackp);
678int ovl_verify_set_fh(struct ovl_fs *ofs, struct dentry *dentry,
679 enum ovl_xattr ox, const struct ovl_fh *fh,
680 bool is_upper, bool set);
681int ovl_verify_origin_xattr(struct ovl_fs *ofs, struct dentry *dentry,
682 enum ovl_xattr ox, struct dentry *real,
683 bool is_upper, bool set);
684struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index,
685 bool connected);
686int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index);
687int ovl_get_index_name_fh(const struct ovl_fh *fh, struct qstr *name);
688int ovl_get_index_name(struct ovl_fs *ofs, struct dentry *origin,
689 struct qstr *name);
690struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh);
691struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
692 struct dentry *origin, bool verify);
693int ovl_path_next(int idx, struct dentry *dentry, struct path *path,
694 const struct ovl_layer **layer);
695int ovl_verify_lowerdata(struct dentry *dentry);
696struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
697 unsigned int flags);
698bool ovl_lower_positive(struct dentry *dentry);
699
700static inline int ovl_verify_origin_fh(struct ovl_fs *ofs, struct dentry *upper,
701 const struct ovl_fh *fh, bool set)
702{
703 return ovl_verify_set_fh(ofs, dentry: upper, ox: OVL_XATTR_ORIGIN, fh, is_upper: false, set);
704}
705
706static inline int ovl_verify_origin(struct ovl_fs *ofs, struct dentry *upper,
707 struct dentry *origin, bool set)
708{
709 return ovl_verify_origin_xattr(ofs, dentry: upper, ox: OVL_XATTR_ORIGIN, real: origin,
710 is_upper: false, set);
711}
712
713static inline int ovl_verify_upper(struct ovl_fs *ofs, struct dentry *index,
714 struct dentry *upper, bool set)
715{
716 return ovl_verify_origin_xattr(ofs, dentry: index, ox: OVL_XATTR_UPPER, real: upper,
717 is_upper: true, set);
718}
719
720/* readdir.c */
721extern const struct file_operations ovl_dir_operations;
722struct file *ovl_dir_real_file(const struct file *file, bool want_upper);
723int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list);
724void ovl_cleanup_whiteouts(struct ovl_fs *ofs, struct dentry *upper,
725 struct list_head *list);
726void ovl_cache_free(struct list_head *list);
727void ovl_dir_cache_free(struct inode *inode);
728int ovl_check_d_type_supported(const struct path *realpath);
729int ovl_workdir_cleanup(struct ovl_fs *ofs, struct inode *dir,
730 struct vfsmount *mnt, struct dentry *dentry, int level);
731int ovl_indexdir_cleanup(struct ovl_fs *ofs);
732
733/*
734 * Can we iterate real dir directly?
735 *
736 * Non-merge dir may contain whiteouts from a time it was a merge upper, before
737 * lower dir was removed under it and possibly before it was rotated from upper
738 * to lower layer.
739 */
740static inline bool ovl_dir_is_real(struct inode *dir)
741{
742 return !ovl_test_flag(flag: OVL_WHITEOUTS, inode: dir);
743}
744
745/* inode.c */
746int ovl_set_nlink_upper(struct dentry *dentry);
747int ovl_set_nlink_lower(struct dentry *dentry);
748unsigned int ovl_get_nlink(struct ovl_fs *ofs, struct dentry *lowerdentry,
749 struct dentry *upperdentry,
750 unsigned int fallback);
751int ovl_permission(struct mnt_idmap *idmap, struct inode *inode,
752 int mask);
753
754#ifdef CONFIG_FS_POSIX_ACL
755struct posix_acl *do_ovl_get_acl(struct mnt_idmap *idmap,
756 struct inode *inode, int type,
757 bool rcu, bool noperm);
758static inline struct posix_acl *ovl_get_inode_acl(struct inode *inode, int type,
759 bool rcu)
760{
761 return do_ovl_get_acl(idmap: &nop_mnt_idmap, inode, type, rcu, noperm: true);
762}
763static inline struct posix_acl *ovl_get_acl(struct mnt_idmap *idmap,
764 struct dentry *dentry, int type)
765{
766 return do_ovl_get_acl(idmap, inode: d_inode(dentry), type, rcu: false, noperm: false);
767}
768int ovl_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
769 struct posix_acl *acl, int type);
770struct posix_acl *ovl_get_acl_path(const struct path *path,
771 const char *acl_name, bool noperm);
772#else
773#define ovl_get_inode_acl NULL
774#define ovl_get_acl NULL
775#define ovl_set_acl NULL
776static inline struct posix_acl *ovl_get_acl_path(const struct path *path,
777 const char *acl_name,
778 bool noperm)
779{
780 return NULL;
781}
782#endif
783
784int ovl_update_time(struct inode *inode, int flags);
785bool ovl_is_private_xattr(struct super_block *sb, const char *name);
786
787struct ovl_inode_params {
788 struct inode *newinode;
789 struct dentry *upperdentry;
790 struct ovl_entry *oe;
791 bool index;
792 char *redirect;
793 char *lowerdata_redirect;
794};
795void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip,
796 unsigned long ino, int fsid);
797struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev);
798struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
799 bool is_upper);
800bool ovl_lookup_trap_inode(struct super_block *sb, struct dentry *dir);
801struct inode *ovl_get_trap_inode(struct super_block *sb, struct dentry *dir);
802struct inode *ovl_get_inode(struct super_block *sb,
803 struct ovl_inode_params *oip);
804void ovl_copyattr(struct inode *to);
805
806/* vfs inode flags copied from real to ovl inode */
807#define OVL_COPY_I_FLAGS_MASK (S_SYNC | S_NOATIME | S_APPEND | S_IMMUTABLE)
808/* vfs inode flags read from overlay.protattr xattr to ovl inode */
809#define OVL_PROT_I_FLAGS_MASK (S_APPEND | S_IMMUTABLE)
810
811/*
812 * fileattr flags copied from lower to upper inode on copy up.
813 * We cannot copy up immutable/append-only flags, because that would prevent
814 * linking temp inode to upper dir, so we store them in xattr instead.
815 */
816#define OVL_COPY_FS_FLAGS_MASK (FS_SYNC_FL | FS_NOATIME_FL)
817#define OVL_COPY_FSX_FLAGS_MASK (FS_XFLAG_SYNC | FS_XFLAG_NOATIME)
818#define OVL_PROT_FS_FLAGS_MASK (FS_APPEND_FL | FS_IMMUTABLE_FL)
819#define OVL_PROT_FSX_FLAGS_MASK (FS_XFLAG_APPEND | FS_XFLAG_IMMUTABLE)
820
821void ovl_check_protattr(struct inode *inode, struct dentry *upper);
822int ovl_set_protattr(struct inode *inode, struct dentry *upper,
823 struct fileattr *fa);
824
825static inline void ovl_copyflags(struct inode *from, struct inode *to)
826{
827 unsigned int mask = OVL_COPY_I_FLAGS_MASK;
828
829 inode_set_flags(inode: to, flags: from->i_flags & mask, mask);
830}
831
832/* dir.c */
833extern const struct inode_operations ovl_dir_inode_operations;
834int ovl_cleanup_and_whiteout(struct ovl_fs *ofs, struct inode *dir,
835 struct dentry *dentry);
836struct ovl_cattr {
837 dev_t rdev;
838 umode_t mode;
839 const char *link;
840 struct dentry *hardlink;
841};
842
843#define OVL_CATTR(m) (&(struct ovl_cattr) { .mode = (m) })
844
845int ovl_mkdir_real(struct ovl_fs *ofs, struct inode *dir,
846 struct dentry **newdentry, umode_t mode);
847struct dentry *ovl_create_real(struct ovl_fs *ofs,
848 struct inode *dir, struct dentry *newdentry,
849 struct ovl_cattr *attr);
850int ovl_cleanup(struct ovl_fs *ofs, struct inode *dir, struct dentry *dentry);
851struct dentry *ovl_lookup_temp(struct ovl_fs *ofs, struct dentry *workdir);
852struct dentry *ovl_create_temp(struct ovl_fs *ofs, struct dentry *workdir,
853 struct ovl_cattr *attr);
854
855/* file.c */
856extern const struct file_operations ovl_file_operations;
857int ovl_real_fileattr_get(const struct path *realpath, struct fileattr *fa);
858int ovl_real_fileattr_set(const struct path *realpath, struct fileattr *fa);
859int ovl_fileattr_get(struct dentry *dentry, struct fileattr *fa);
860int ovl_fileattr_set(struct mnt_idmap *idmap,
861 struct dentry *dentry, struct fileattr *fa);
862
863/* copy_up.c */
864int ovl_copy_up(struct dentry *dentry);
865int ovl_copy_up_with_data(struct dentry *dentry);
866int ovl_maybe_copy_up(struct dentry *dentry, int flags);
867int ovl_copy_xattr(struct super_block *sb, const struct path *path, struct dentry *new);
868int ovl_set_attr(struct ovl_fs *ofs, struct dentry *upper, struct kstat *stat);
869struct ovl_fh *ovl_encode_real_fh(struct ovl_fs *ofs, struct dentry *real,
870 bool is_upper);
871struct ovl_fh *ovl_get_origin_fh(struct ovl_fs *ofs, struct dentry *origin);
872int ovl_set_origin_fh(struct ovl_fs *ofs, const struct ovl_fh *fh,
873 struct dentry *upper);
874
875/* export.c */
876extern const struct export_operations ovl_export_operations;
877extern const struct export_operations ovl_export_fid_operations;
878
879/* super.c */
880int ovl_fill_super(struct super_block *sb, struct fs_context *fc);
881
882/* Will this overlay be forced to mount/remount ro? */
883static inline bool ovl_force_readonly(struct ovl_fs *ofs)
884{
885 return (!ovl_upper_mnt(ofs) || !ofs->workdir);
886}
887
888/* xattr.c */
889
890const struct xattr_handler * const *ovl_xattr_handlers(struct ovl_fs *ofs);
891int ovl_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
892 struct iattr *attr);
893int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
894 struct kstat *stat, u32 request_mask, unsigned int flags);
895ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
896

source code of linux/fs/overlayfs/overlayfs.h