xref: /openbmc/linux/fs/overlayfs/overlayfs.h (revision 1f9b7512)
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 "ovl_entry.h"
11 
12 #undef pr_fmt
13 #define pr_fmt(fmt) "overlayfs: " fmt
14 
15 enum ovl_path_type {
16 	__OVL_PATH_UPPER	= (1 << 0),
17 	__OVL_PATH_MERGE	= (1 << 1),
18 	__OVL_PATH_ORIGIN	= (1 << 2),
19 };
20 
21 #define OVL_TYPE_UPPER(type)	((type) & __OVL_PATH_UPPER)
22 #define OVL_TYPE_MERGE(type)	((type) & __OVL_PATH_MERGE)
23 #define OVL_TYPE_ORIGIN(type)	((type) & __OVL_PATH_ORIGIN)
24 
25 #define OVL_XATTR_PREFIX XATTR_TRUSTED_PREFIX "overlay."
26 #define OVL_XATTR_OPAQUE OVL_XATTR_PREFIX "opaque"
27 #define OVL_XATTR_REDIRECT OVL_XATTR_PREFIX "redirect"
28 #define OVL_XATTR_ORIGIN OVL_XATTR_PREFIX "origin"
29 #define OVL_XATTR_IMPURE OVL_XATTR_PREFIX "impure"
30 #define OVL_XATTR_NLINK OVL_XATTR_PREFIX "nlink"
31 #define OVL_XATTR_UPPER OVL_XATTR_PREFIX "upper"
32 #define OVL_XATTR_METACOPY OVL_XATTR_PREFIX "metacopy"
33 
34 enum ovl_inode_flag {
35 	/* Pure upper dir that may contain non pure upper entries */
36 	OVL_IMPURE,
37 	/* Non-merge dir that may contain whiteout entries */
38 	OVL_WHITEOUTS,
39 	OVL_INDEX,
40 	OVL_UPPERDATA,
41 	/* Inode number will remain constant over copy up. */
42 	OVL_CONST_INO,
43 };
44 
45 enum ovl_entry_flag {
46 	OVL_E_UPPER_ALIAS,
47 	OVL_E_OPAQUE,
48 	OVL_E_CONNECTED,
49 };
50 
51 enum {
52 	OVL_XINO_OFF,
53 	OVL_XINO_AUTO,
54 	OVL_XINO_ON,
55 };
56 
57 /*
58  * The tuple (fh,uuid) is a universal unique identifier for a copy up origin,
59  * where:
60  * origin.fh	- exported file handle of the lower file
61  * origin.uuid	- uuid of the lower filesystem
62  */
63 #define OVL_FH_VERSION	0
64 #define OVL_FH_MAGIC	0xfb
65 
66 /* CPU byte order required for fid decoding:  */
67 #define OVL_FH_FLAG_BIG_ENDIAN	(1 << 0)
68 #define OVL_FH_FLAG_ANY_ENDIAN	(1 << 1)
69 /* Is the real inode encoded in fid an upper inode? */
70 #define OVL_FH_FLAG_PATH_UPPER	(1 << 2)
71 
72 #define OVL_FH_FLAG_ALL (OVL_FH_FLAG_BIG_ENDIAN | OVL_FH_FLAG_ANY_ENDIAN | \
73 			 OVL_FH_FLAG_PATH_UPPER)
74 
75 #if defined(__LITTLE_ENDIAN)
76 #define OVL_FH_FLAG_CPU_ENDIAN 0
77 #elif defined(__BIG_ENDIAN)
78 #define OVL_FH_FLAG_CPU_ENDIAN OVL_FH_FLAG_BIG_ENDIAN
79 #else
80 #error Endianness not defined
81 #endif
82 
83 /* The type used to be returned by overlay exportfs for misaligned fid */
84 #define OVL_FILEID_V0	0xfb
85 /* The type returned by overlay exportfs for 32bit aligned fid */
86 #define OVL_FILEID_V1	0xf8
87 
88 /* On-disk format for "origin" file handle */
89 struct ovl_fb {
90 	u8 version;	/* 0 */
91 	u8 magic;	/* 0xfb */
92 	u8 len;		/* size of this header + size of fid */
93 	u8 flags;	/* OVL_FH_FLAG_* */
94 	u8 type;	/* fid_type of fid */
95 	uuid_t uuid;	/* uuid of filesystem */
96 	u32 fid[];	/* file identifier should be 32bit aligned in-memory */
97 } __packed;
98 
99 /* In-memory and on-wire format for overlay file handle */
100 struct ovl_fh {
101 	u8 padding[3];	/* make sure fb.fid is 32bit aligned */
102 	union {
103 		struct ovl_fb fb;
104 		u8 buf[0];
105 	};
106 } __packed;
107 
108 #define OVL_FH_WIRE_OFFSET	offsetof(struct ovl_fh, fb)
109 #define OVL_FH_LEN(fh)		(OVL_FH_WIRE_OFFSET + (fh)->fb.len)
110 #define OVL_FH_FID_OFFSET	(OVL_FH_WIRE_OFFSET + \
111 				 offsetof(struct ovl_fb, fid))
112 
113 static inline int ovl_do_rmdir(struct inode *dir, struct dentry *dentry)
114 {
115 	int err = vfs_rmdir(dir, dentry);
116 
117 	pr_debug("rmdir(%pd2) = %i\n", dentry, err);
118 	return err;
119 }
120 
121 static inline int ovl_do_unlink(struct inode *dir, struct dentry *dentry)
122 {
123 	int err = vfs_unlink(dir, dentry, NULL);
124 
125 	pr_debug("unlink(%pd2) = %i\n", dentry, err);
126 	return err;
127 }
128 
129 static inline int ovl_do_link(struct dentry *old_dentry, struct inode *dir,
130 			      struct dentry *new_dentry)
131 {
132 	int err = vfs_link(old_dentry, dir, new_dentry, NULL);
133 
134 	pr_debug("link(%pd2, %pd2) = %i\n", old_dentry, new_dentry, err);
135 	return err;
136 }
137 
138 static inline int ovl_do_create(struct inode *dir, struct dentry *dentry,
139 				umode_t mode)
140 {
141 	int err = vfs_create(dir, dentry, mode, true);
142 
143 	pr_debug("create(%pd2, 0%o) = %i\n", dentry, mode, err);
144 	return err;
145 }
146 
147 static inline int ovl_do_mkdir(struct inode *dir, struct dentry *dentry,
148 			       umode_t mode)
149 {
150 	int err = vfs_mkdir(dir, dentry, mode);
151 	pr_debug("mkdir(%pd2, 0%o) = %i\n", dentry, mode, err);
152 	return err;
153 }
154 
155 static inline int ovl_do_mknod(struct inode *dir, struct dentry *dentry,
156 			       umode_t mode, dev_t dev)
157 {
158 	int err = vfs_mknod(dir, dentry, mode, dev);
159 
160 	pr_debug("mknod(%pd2, 0%o, 0%o) = %i\n", dentry, mode, dev, err);
161 	return err;
162 }
163 
164 static inline int ovl_do_symlink(struct inode *dir, struct dentry *dentry,
165 				 const char *oldname)
166 {
167 	int err = vfs_symlink(dir, dentry, oldname);
168 
169 	pr_debug("symlink(\"%s\", %pd2) = %i\n", oldname, dentry, err);
170 	return err;
171 }
172 
173 static inline int ovl_do_setxattr(struct dentry *dentry, const char *name,
174 				  const void *value, size_t size, int flags)
175 {
176 	int err = vfs_setxattr(dentry, name, value, size, flags);
177 	pr_debug("setxattr(%pd2, \"%s\", \"%*pE\", %zu, 0x%x) = %i\n",
178 		 dentry, name, min((int)size, 48), value, size, flags, err);
179 	return err;
180 }
181 
182 static inline int ovl_do_removexattr(struct dentry *dentry, const char *name)
183 {
184 	int err = vfs_removexattr(dentry, name);
185 	pr_debug("removexattr(%pd2, \"%s\") = %i\n", dentry, name, err);
186 	return err;
187 }
188 
189 static inline int ovl_do_rename(struct inode *olddir, struct dentry *olddentry,
190 				struct inode *newdir, struct dentry *newdentry,
191 				unsigned int flags)
192 {
193 	int err;
194 
195 	pr_debug("rename(%pd2, %pd2, 0x%x)\n", olddentry, newdentry, flags);
196 	err = vfs_rename(olddir, olddentry, newdir, newdentry, NULL, flags);
197 	if (err) {
198 		pr_debug("...rename(%pd2, %pd2, ...) = %i\n",
199 			 olddentry, newdentry, err);
200 	}
201 	return err;
202 }
203 
204 static inline int ovl_do_whiteout(struct inode *dir, struct dentry *dentry)
205 {
206 	int err = vfs_whiteout(dir, dentry);
207 	pr_debug("whiteout(%pd2) = %i\n", dentry, err);
208 	return err;
209 }
210 
211 static inline struct dentry *ovl_do_tmpfile(struct dentry *dentry, umode_t mode)
212 {
213 	struct dentry *ret = vfs_tmpfile(dentry, mode, 0);
214 	int err = PTR_ERR_OR_ZERO(ret);
215 
216 	pr_debug("tmpfile(%pd2, 0%o) = %i\n", dentry, mode, err);
217 	return ret;
218 }
219 
220 static inline bool ovl_open_flags_need_copy_up(int flags)
221 {
222 	if (!flags)
223 		return false;
224 
225 	return ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC));
226 }
227 
228 /* util.c */
229 int ovl_want_write(struct dentry *dentry);
230 void ovl_drop_write(struct dentry *dentry);
231 struct dentry *ovl_workdir(struct dentry *dentry);
232 const struct cred *ovl_override_creds(struct super_block *sb);
233 int ovl_can_decode_fh(struct super_block *sb);
234 struct dentry *ovl_indexdir(struct super_block *sb);
235 bool ovl_index_all(struct super_block *sb);
236 bool ovl_verify_lower(struct super_block *sb);
237 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
238 bool ovl_dentry_remote(struct dentry *dentry);
239 void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry,
240 			     unsigned int mask);
241 bool ovl_dentry_weird(struct dentry *dentry);
242 enum ovl_path_type ovl_path_type(struct dentry *dentry);
243 void ovl_path_upper(struct dentry *dentry, struct path *path);
244 void ovl_path_lower(struct dentry *dentry, struct path *path);
245 void ovl_path_lowerdata(struct dentry *dentry, struct path *path);
246 enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
247 struct dentry *ovl_dentry_upper(struct dentry *dentry);
248 struct dentry *ovl_dentry_lower(struct dentry *dentry);
249 struct dentry *ovl_dentry_lowerdata(struct dentry *dentry);
250 const struct ovl_layer *ovl_layer_lower(struct dentry *dentry);
251 struct dentry *ovl_dentry_real(struct dentry *dentry);
252 struct dentry *ovl_i_dentry_upper(struct inode *inode);
253 struct inode *ovl_inode_upper(struct inode *inode);
254 struct inode *ovl_inode_lower(struct inode *inode);
255 struct inode *ovl_inode_lowerdata(struct inode *inode);
256 struct inode *ovl_inode_real(struct inode *inode);
257 struct inode *ovl_inode_realdata(struct inode *inode);
258 struct ovl_dir_cache *ovl_dir_cache(struct inode *inode);
259 void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache);
260 void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry);
261 void ovl_dentry_clear_flag(unsigned long flag, struct dentry *dentry);
262 bool ovl_dentry_test_flag(unsigned long flag, struct dentry *dentry);
263 bool ovl_dentry_is_opaque(struct dentry *dentry);
264 bool ovl_dentry_is_whiteout(struct dentry *dentry);
265 void ovl_dentry_set_opaque(struct dentry *dentry);
266 bool ovl_dentry_has_upper_alias(struct dentry *dentry);
267 void ovl_dentry_set_upper_alias(struct dentry *dentry);
268 bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags);
269 bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags);
270 bool ovl_has_upperdata(struct inode *inode);
271 void ovl_set_upperdata(struct inode *inode);
272 bool ovl_redirect_dir(struct super_block *sb);
273 const char *ovl_dentry_get_redirect(struct dentry *dentry);
274 void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect);
275 void ovl_inode_update(struct inode *inode, struct dentry *upperdentry);
276 void ovl_dir_modified(struct dentry *dentry, bool impurity);
277 u64 ovl_dentry_version_get(struct dentry *dentry);
278 bool ovl_is_whiteout(struct dentry *dentry);
279 struct file *ovl_path_open(struct path *path, int flags);
280 int ovl_copy_up_start(struct dentry *dentry, int flags);
281 void ovl_copy_up_end(struct dentry *dentry);
282 bool ovl_already_copied_up(struct dentry *dentry, int flags);
283 bool ovl_check_origin_xattr(struct dentry *dentry);
284 bool ovl_check_dir_xattr(struct dentry *dentry, const char *name);
285 int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
286 		       const char *name, const void *value, size_t size,
287 		       int xerr);
288 int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry);
289 void ovl_set_flag(unsigned long flag, struct inode *inode);
290 void ovl_clear_flag(unsigned long flag, struct inode *inode);
291 bool ovl_test_flag(unsigned long flag, struct inode *inode);
292 bool ovl_inuse_trylock(struct dentry *dentry);
293 void ovl_inuse_unlock(struct dentry *dentry);
294 bool ovl_is_inuse(struct dentry *dentry);
295 bool ovl_need_index(struct dentry *dentry);
296 int ovl_nlink_start(struct dentry *dentry);
297 void ovl_nlink_end(struct dentry *dentry);
298 int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir);
299 int ovl_check_metacopy_xattr(struct dentry *dentry);
300 bool ovl_is_metacopy_dentry(struct dentry *dentry);
301 char *ovl_get_redirect_xattr(struct dentry *dentry, int padding);
302 ssize_t ovl_getxattr(struct dentry *dentry, char *name, char **value,
303 		     size_t padding);
304 
305 static inline bool ovl_is_impuredir(struct dentry *dentry)
306 {
307 	return ovl_check_dir_xattr(dentry, OVL_XATTR_IMPURE);
308 }
309 
310 /*
311  * With xino=auto, we do best effort to keep all inodes on same st_dev and
312  * d_ino consistent with st_ino.
313  * With xino=on, we do the same effort but we warn if we failed.
314  */
315 static inline bool ovl_xino_warn(struct super_block *sb)
316 {
317 	return OVL_FS(sb)->config.xino == OVL_XINO_ON;
318 }
319 
320 /* All layers on same fs? */
321 static inline bool ovl_same_fs(struct super_block *sb)
322 {
323 	return OVL_FS(sb)->xino_mode == 0;
324 }
325 
326 /* All overlay inodes have same st_dev? */
327 static inline bool ovl_same_dev(struct super_block *sb)
328 {
329 	return OVL_FS(sb)->xino_mode >= 0;
330 }
331 
332 static inline unsigned int ovl_xino_bits(struct super_block *sb)
333 {
334 	return ovl_same_dev(sb) ? OVL_FS(sb)->xino_mode : 0;
335 }
336 
337 static inline void ovl_inode_lock(struct inode *inode)
338 {
339 	mutex_lock(&OVL_I(inode)->lock);
340 }
341 
342 static inline int ovl_inode_lock_interruptible(struct inode *inode)
343 {
344 	return mutex_lock_interruptible(&OVL_I(inode)->lock);
345 }
346 
347 static inline void ovl_inode_unlock(struct inode *inode)
348 {
349 	mutex_unlock(&OVL_I(inode)->lock);
350 }
351 
352 
353 /* namei.c */
354 int ovl_check_fb_len(struct ovl_fb *fb, int fb_len);
355 
356 static inline int ovl_check_fh_len(struct ovl_fh *fh, int fh_len)
357 {
358 	if (fh_len < sizeof(struct ovl_fh))
359 		return -EINVAL;
360 
361 	return ovl_check_fb_len(&fh->fb, fh_len - OVL_FH_WIRE_OFFSET);
362 }
363 
364 struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt,
365 				  bool connected);
366 int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
367 			struct dentry *upperdentry, struct ovl_path **stackp);
368 int ovl_verify_set_fh(struct dentry *dentry, const char *name,
369 		      struct dentry *real, bool is_upper, bool set);
370 struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index);
371 int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index);
372 int ovl_get_index_name(struct dentry *origin, struct qstr *name);
373 struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh);
374 struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
375 				struct dentry *origin, bool verify);
376 int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
377 struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
378 			  unsigned int flags);
379 bool ovl_lower_positive(struct dentry *dentry);
380 
381 static inline int ovl_verify_origin(struct dentry *upper,
382 				    struct dentry *origin, bool set)
383 {
384 	return ovl_verify_set_fh(upper, OVL_XATTR_ORIGIN, origin, false, set);
385 }
386 
387 static inline int ovl_verify_upper(struct dentry *index,
388 				    struct dentry *upper, bool set)
389 {
390 	return ovl_verify_set_fh(index, OVL_XATTR_UPPER, upper, true, set);
391 }
392 
393 /* readdir.c */
394 extern const struct file_operations ovl_dir_operations;
395 int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list);
396 void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list);
397 void ovl_cache_free(struct list_head *list);
398 void ovl_dir_cache_free(struct inode *inode);
399 int ovl_check_d_type_supported(struct path *realpath);
400 int ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
401 			struct dentry *dentry, int level);
402 int ovl_indexdir_cleanup(struct ovl_fs *ofs);
403 
404 /* inode.c */
405 int ovl_set_nlink_upper(struct dentry *dentry);
406 int ovl_set_nlink_lower(struct dentry *dentry);
407 unsigned int ovl_get_nlink(struct dentry *lowerdentry,
408 			   struct dentry *upperdentry,
409 			   unsigned int fallback);
410 int ovl_setattr(struct dentry *dentry, struct iattr *attr);
411 int ovl_getattr(const struct path *path, struct kstat *stat,
412 		u32 request_mask, unsigned int flags);
413 int ovl_permission(struct inode *inode, int mask);
414 int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
415 		  const void *value, size_t size, int flags);
416 int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
417 		  void *value, size_t size);
418 ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
419 struct posix_acl *ovl_get_acl(struct inode *inode, int type);
420 int ovl_update_time(struct inode *inode, struct timespec64 *ts, int flags);
421 bool ovl_is_private_xattr(const char *name);
422 
423 struct ovl_inode_params {
424 	struct inode *newinode;
425 	struct dentry *upperdentry;
426 	struct ovl_path *lowerpath;
427 	bool index;
428 	unsigned int numlower;
429 	char *redirect;
430 	struct dentry *lowerdata;
431 };
432 void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip,
433 		    unsigned long ino, int fsid);
434 struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev);
435 struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
436 			       bool is_upper);
437 bool ovl_lookup_trap_inode(struct super_block *sb, struct dentry *dir);
438 struct inode *ovl_get_trap_inode(struct super_block *sb, struct dentry *dir);
439 struct inode *ovl_get_inode(struct super_block *sb,
440 			    struct ovl_inode_params *oip);
441 static inline void ovl_copyattr(struct inode *from, struct inode *to)
442 {
443 	to->i_uid = from->i_uid;
444 	to->i_gid = from->i_gid;
445 	to->i_mode = from->i_mode;
446 	to->i_atime = from->i_atime;
447 	to->i_mtime = from->i_mtime;
448 	to->i_ctime = from->i_ctime;
449 	i_size_write(to, i_size_read(from));
450 }
451 
452 static inline void ovl_copyflags(struct inode *from, struct inode *to)
453 {
454 	unsigned int mask = S_SYNC | S_IMMUTABLE | S_APPEND | S_NOATIME;
455 
456 	inode_set_flags(to, from->i_flags & mask, mask);
457 }
458 
459 /* dir.c */
460 extern const struct inode_operations ovl_dir_inode_operations;
461 int ovl_cleanup_and_whiteout(struct ovl_fs *ofs, struct inode *dir,
462 			     struct dentry *dentry);
463 struct ovl_cattr {
464 	dev_t rdev;
465 	umode_t mode;
466 	const char *link;
467 	struct dentry *hardlink;
468 };
469 
470 #define OVL_CATTR(m) (&(struct ovl_cattr) { .mode = (m) })
471 
472 struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry,
473 			       struct ovl_cattr *attr);
474 int ovl_cleanup(struct inode *dir, struct dentry *dentry);
475 struct dentry *ovl_lookup_temp(struct dentry *workdir);
476 struct dentry *ovl_create_temp(struct dentry *workdir, struct ovl_cattr *attr);
477 
478 /* file.c */
479 extern const struct file_operations ovl_file_operations;
480 int __init ovl_aio_request_cache_init(void);
481 void ovl_aio_request_cache_destroy(void);
482 
483 /* copy_up.c */
484 int ovl_copy_up(struct dentry *dentry);
485 int ovl_copy_up_with_data(struct dentry *dentry);
486 int ovl_copy_up_flags(struct dentry *dentry, int flags);
487 int ovl_maybe_copy_up(struct dentry *dentry, int flags);
488 int ovl_copy_xattr(struct dentry *old, struct dentry *new);
489 int ovl_set_attr(struct dentry *upper, struct kstat *stat);
490 struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper);
491 int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
492 		   struct dentry *upper);
493 
494 /* export.c */
495 extern const struct export_operations ovl_export_operations;
496