xref: /openbmc/linux/fs/overlayfs/overlayfs.h (revision ba61bb17)
1 /*
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/kernel.h>
11 #include <linux/uuid.h>
12 #include "ovl_entry.h"
13 
14 enum ovl_path_type {
15 	__OVL_PATH_UPPER	= (1 << 0),
16 	__OVL_PATH_MERGE	= (1 << 1),
17 	__OVL_PATH_ORIGIN	= (1 << 2),
18 };
19 
20 #define OVL_TYPE_UPPER(type)	((type) & __OVL_PATH_UPPER)
21 #define OVL_TYPE_MERGE(type)	((type) & __OVL_PATH_MERGE)
22 #define OVL_TYPE_ORIGIN(type)	((type) & __OVL_PATH_ORIGIN)
23 
24 #define OVL_XATTR_PREFIX XATTR_TRUSTED_PREFIX "overlay."
25 #define OVL_XATTR_OPAQUE OVL_XATTR_PREFIX "opaque"
26 #define OVL_XATTR_REDIRECT OVL_XATTR_PREFIX "redirect"
27 #define OVL_XATTR_ORIGIN OVL_XATTR_PREFIX "origin"
28 #define OVL_XATTR_IMPURE OVL_XATTR_PREFIX "impure"
29 #define OVL_XATTR_NLINK OVL_XATTR_PREFIX "nlink"
30 #define OVL_XATTR_UPPER OVL_XATTR_PREFIX "upper"
31 
32 enum ovl_inode_flag {
33 	/* Pure upper dir that may contain non pure upper entries */
34 	OVL_IMPURE,
35 	/* Non-merge dir that may contain whiteout entries */
36 	OVL_WHITEOUTS,
37 	OVL_INDEX,
38 };
39 
40 enum ovl_entry_flag {
41 	OVL_E_UPPER_ALIAS,
42 	OVL_E_OPAQUE,
43 	OVL_E_CONNECTED,
44 };
45 
46 /*
47  * The tuple (fh,uuid) is a universal unique identifier for a copy up origin,
48  * where:
49  * origin.fh	- exported file handle of the lower file
50  * origin.uuid	- uuid of the lower filesystem
51  */
52 #define OVL_FH_VERSION	0
53 #define OVL_FH_MAGIC	0xfb
54 
55 /* CPU byte order required for fid decoding:  */
56 #define OVL_FH_FLAG_BIG_ENDIAN	(1 << 0)
57 #define OVL_FH_FLAG_ANY_ENDIAN	(1 << 1)
58 /* Is the real inode encoded in fid an upper inode? */
59 #define OVL_FH_FLAG_PATH_UPPER	(1 << 2)
60 
61 #define OVL_FH_FLAG_ALL (OVL_FH_FLAG_BIG_ENDIAN | OVL_FH_FLAG_ANY_ENDIAN | \
62 			 OVL_FH_FLAG_PATH_UPPER)
63 
64 #if defined(__LITTLE_ENDIAN)
65 #define OVL_FH_FLAG_CPU_ENDIAN 0
66 #elif defined(__BIG_ENDIAN)
67 #define OVL_FH_FLAG_CPU_ENDIAN OVL_FH_FLAG_BIG_ENDIAN
68 #else
69 #error Endianness not defined
70 #endif
71 
72 /* The type returned by overlay exportfs ops when encoding an ovl_fh handle */
73 #define OVL_FILEID	0xfb
74 
75 /* On-disk and in-memeory format for redirect by file handle */
76 struct ovl_fh {
77 	u8 version;	/* 0 */
78 	u8 magic;	/* 0xfb */
79 	u8 len;		/* size of this header + size of fid */
80 	u8 flags;	/* OVL_FH_FLAG_* */
81 	u8 type;	/* fid_type of fid */
82 	uuid_t uuid;	/* uuid of filesystem */
83 	u8 fid[0];	/* file identifier */
84 } __packed;
85 
86 static inline int ovl_do_rmdir(struct inode *dir, struct dentry *dentry)
87 {
88 	int err = vfs_rmdir(dir, dentry);
89 
90 	pr_debug("rmdir(%pd2) = %i\n", dentry, err);
91 	return err;
92 }
93 
94 static inline int ovl_do_unlink(struct inode *dir, struct dentry *dentry)
95 {
96 	int err = vfs_unlink(dir, dentry, NULL);
97 
98 	pr_debug("unlink(%pd2) = %i\n", dentry, err);
99 	return err;
100 }
101 
102 static inline int ovl_do_link(struct dentry *old_dentry, struct inode *dir,
103 			      struct dentry *new_dentry)
104 {
105 	int err = vfs_link(old_dentry, dir, new_dentry, NULL);
106 
107 	pr_debug("link(%pd2, %pd2) = %i\n", old_dentry, new_dentry, err);
108 	return err;
109 }
110 
111 static inline int ovl_do_create(struct inode *dir, struct dentry *dentry,
112 				umode_t mode)
113 {
114 	int err = vfs_create(dir, dentry, mode, true);
115 
116 	pr_debug("create(%pd2, 0%o) = %i\n", dentry, mode, err);
117 	return err;
118 }
119 
120 static inline int ovl_do_mkdir(struct inode *dir, struct dentry *dentry,
121 			       umode_t mode)
122 {
123 	int err = vfs_mkdir(dir, dentry, mode);
124 	pr_debug("mkdir(%pd2, 0%o) = %i\n", dentry, mode, err);
125 	return err;
126 }
127 
128 static inline int ovl_do_mknod(struct inode *dir, struct dentry *dentry,
129 			       umode_t mode, dev_t dev)
130 {
131 	int err = vfs_mknod(dir, dentry, mode, dev);
132 
133 	pr_debug("mknod(%pd2, 0%o, 0%o) = %i\n", dentry, mode, dev, err);
134 	return err;
135 }
136 
137 static inline int ovl_do_symlink(struct inode *dir, struct dentry *dentry,
138 				 const char *oldname)
139 {
140 	int err = vfs_symlink(dir, dentry, oldname);
141 
142 	pr_debug("symlink(\"%s\", %pd2) = %i\n", oldname, dentry, err);
143 	return err;
144 }
145 
146 static inline int ovl_do_setxattr(struct dentry *dentry, const char *name,
147 				  const void *value, size_t size, int flags)
148 {
149 	int err = vfs_setxattr(dentry, name, value, size, flags);
150 	pr_debug("setxattr(%pd2, \"%s\", \"%*s\", 0x%x) = %i\n",
151 		 dentry, name, (int) size, (char *) value, flags, err);
152 	return err;
153 }
154 
155 static inline int ovl_do_removexattr(struct dentry *dentry, const char *name)
156 {
157 	int err = vfs_removexattr(dentry, name);
158 	pr_debug("removexattr(%pd2, \"%s\") = %i\n", dentry, name, err);
159 	return err;
160 }
161 
162 static inline int ovl_do_rename(struct inode *olddir, struct dentry *olddentry,
163 				struct inode *newdir, struct dentry *newdentry,
164 				unsigned int flags)
165 {
166 	int err;
167 
168 	pr_debug("rename(%pd2, %pd2, 0x%x)\n", olddentry, newdentry, flags);
169 	err = vfs_rename(olddir, olddentry, newdir, newdentry, NULL, flags);
170 	if (err) {
171 		pr_debug("...rename(%pd2, %pd2, ...) = %i\n",
172 			 olddentry, newdentry, err);
173 	}
174 	return err;
175 }
176 
177 static inline int ovl_do_whiteout(struct inode *dir, struct dentry *dentry)
178 {
179 	int err = vfs_whiteout(dir, dentry);
180 	pr_debug("whiteout(%pd2) = %i\n", dentry, err);
181 	return err;
182 }
183 
184 static inline struct dentry *ovl_do_tmpfile(struct dentry *dentry, umode_t mode)
185 {
186 	struct dentry *ret = vfs_tmpfile(dentry, mode, 0);
187 	int err = PTR_ERR_OR_ZERO(ret);
188 
189 	pr_debug("tmpfile(%pd2, 0%o) = %i\n", dentry, mode, err);
190 	return ret;
191 }
192 
193 /* util.c */
194 int ovl_want_write(struct dentry *dentry);
195 void ovl_drop_write(struct dentry *dentry);
196 struct dentry *ovl_workdir(struct dentry *dentry);
197 const struct cred *ovl_override_creds(struct super_block *sb);
198 struct super_block *ovl_same_sb(struct super_block *sb);
199 int ovl_can_decode_fh(struct super_block *sb);
200 struct dentry *ovl_indexdir(struct super_block *sb);
201 bool ovl_index_all(struct super_block *sb);
202 bool ovl_verify_lower(struct super_block *sb);
203 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
204 bool ovl_dentry_remote(struct dentry *dentry);
205 bool ovl_dentry_weird(struct dentry *dentry);
206 enum ovl_path_type ovl_path_type(struct dentry *dentry);
207 void ovl_path_upper(struct dentry *dentry, struct path *path);
208 void ovl_path_lower(struct dentry *dentry, struct path *path);
209 enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
210 struct dentry *ovl_dentry_upper(struct dentry *dentry);
211 struct dentry *ovl_dentry_lower(struct dentry *dentry);
212 struct ovl_layer *ovl_layer_lower(struct dentry *dentry);
213 struct dentry *ovl_dentry_real(struct dentry *dentry);
214 struct dentry *ovl_i_dentry_upper(struct inode *inode);
215 struct inode *ovl_inode_upper(struct inode *inode);
216 struct inode *ovl_inode_lower(struct inode *inode);
217 struct inode *ovl_inode_real(struct inode *inode);
218 struct ovl_dir_cache *ovl_dir_cache(struct inode *inode);
219 void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache);
220 void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry);
221 void ovl_dentry_clear_flag(unsigned long flag, struct dentry *dentry);
222 bool ovl_dentry_test_flag(unsigned long flag, struct dentry *dentry);
223 bool ovl_dentry_is_opaque(struct dentry *dentry);
224 bool ovl_dentry_is_whiteout(struct dentry *dentry);
225 void ovl_dentry_set_opaque(struct dentry *dentry);
226 bool ovl_dentry_has_upper_alias(struct dentry *dentry);
227 void ovl_dentry_set_upper_alias(struct dentry *dentry);
228 bool ovl_redirect_dir(struct super_block *sb);
229 const char *ovl_dentry_get_redirect(struct dentry *dentry);
230 void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect);
231 void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
232 		    struct dentry *lowerdentry);
233 void ovl_inode_update(struct inode *inode, struct dentry *upperdentry);
234 void ovl_dentry_version_inc(struct dentry *dentry, bool impurity);
235 u64 ovl_dentry_version_get(struct dentry *dentry);
236 bool ovl_is_whiteout(struct dentry *dentry);
237 struct file *ovl_path_open(struct path *path, int flags);
238 int ovl_copy_up_start(struct dentry *dentry);
239 void ovl_copy_up_end(struct dentry *dentry);
240 bool ovl_check_origin_xattr(struct dentry *dentry);
241 bool ovl_check_dir_xattr(struct dentry *dentry, const char *name);
242 int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
243 		       const char *name, const void *value, size_t size,
244 		       int xerr);
245 int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry);
246 void ovl_set_flag(unsigned long flag, struct inode *inode);
247 void ovl_clear_flag(unsigned long flag, struct inode *inode);
248 bool ovl_test_flag(unsigned long flag, struct inode *inode);
249 bool ovl_inuse_trylock(struct dentry *dentry);
250 void ovl_inuse_unlock(struct dentry *dentry);
251 bool ovl_need_index(struct dentry *dentry);
252 int ovl_nlink_start(struct dentry *dentry, bool *locked);
253 void ovl_nlink_end(struct dentry *dentry, bool locked);
254 int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir);
255 
256 static inline bool ovl_is_impuredir(struct dentry *dentry)
257 {
258 	return ovl_check_dir_xattr(dentry, OVL_XATTR_IMPURE);
259 }
260 
261 static inline unsigned int ovl_xino_bits(struct super_block *sb)
262 {
263 	struct ovl_fs *ofs = sb->s_fs_info;
264 
265 	return ofs->xino_bits;
266 }
267 
268 
269 /* namei.c */
270 int ovl_check_fh_len(struct ovl_fh *fh, int fh_len);
271 struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt,
272 				  bool connected);
273 int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
274 			struct dentry *upperdentry, struct ovl_path **stackp);
275 int ovl_verify_set_fh(struct dentry *dentry, const char *name,
276 		      struct dentry *real, bool is_upper, bool set);
277 struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index);
278 int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index);
279 int ovl_get_index_name(struct dentry *origin, struct qstr *name);
280 struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh);
281 struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
282 				struct dentry *origin, bool verify);
283 int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
284 struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
285 			  unsigned int flags);
286 bool ovl_lower_positive(struct dentry *dentry);
287 
288 static inline int ovl_verify_origin(struct dentry *upper,
289 				    struct dentry *origin, bool set)
290 {
291 	return ovl_verify_set_fh(upper, OVL_XATTR_ORIGIN, origin, false, set);
292 }
293 
294 static inline int ovl_verify_upper(struct dentry *index,
295 				    struct dentry *upper, bool set)
296 {
297 	return ovl_verify_set_fh(index, OVL_XATTR_UPPER, upper, true, set);
298 }
299 
300 /* readdir.c */
301 extern const struct file_operations ovl_dir_operations;
302 int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list);
303 void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list);
304 void ovl_cache_free(struct list_head *list);
305 void ovl_dir_cache_free(struct inode *inode);
306 int ovl_check_d_type_supported(struct path *realpath);
307 void ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
308 			 struct dentry *dentry, int level);
309 int ovl_indexdir_cleanup(struct ovl_fs *ofs);
310 
311 /* inode.c */
312 int ovl_set_nlink_upper(struct dentry *dentry);
313 int ovl_set_nlink_lower(struct dentry *dentry);
314 unsigned int ovl_get_nlink(struct dentry *lowerdentry,
315 			   struct dentry *upperdentry,
316 			   unsigned int fallback);
317 int ovl_setattr(struct dentry *dentry, struct iattr *attr);
318 int ovl_getattr(const struct path *path, struct kstat *stat,
319 		u32 request_mask, unsigned int flags);
320 int ovl_permission(struct inode *inode, int mask);
321 int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
322 		  const void *value, size_t size, int flags);
323 int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
324 		  void *value, size_t size);
325 ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
326 struct posix_acl *ovl_get_acl(struct inode *inode, int type);
327 int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags);
328 int ovl_update_time(struct inode *inode, struct timespec64 *ts, int flags);
329 bool ovl_is_private_xattr(const char *name);
330 
331 struct ovl_inode_params {
332 	struct inode *newinode;
333 	struct dentry *upperdentry;
334 	struct ovl_path *lowerpath;
335 	struct dentry *index;
336 	unsigned int numlower;
337 };
338 struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev);
339 struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
340 			       bool is_upper);
341 struct inode *ovl_get_inode(struct super_block *sb,
342 			    struct ovl_inode_params *oip);
343 static inline void ovl_copyattr(struct inode *from, struct inode *to)
344 {
345 	to->i_uid = from->i_uid;
346 	to->i_gid = from->i_gid;
347 	to->i_mode = from->i_mode;
348 	to->i_atime = from->i_atime;
349 	to->i_mtime = from->i_mtime;
350 	to->i_ctime = from->i_ctime;
351 }
352 
353 /* dir.c */
354 extern const struct inode_operations ovl_dir_inode_operations;
355 int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,
356 			     struct dentry *dentry);
357 struct ovl_cattr {
358 	dev_t rdev;
359 	umode_t mode;
360 	const char *link;
361 	struct dentry *hardlink;
362 };
363 
364 #define OVL_CATTR(m) (&(struct ovl_cattr) { .mode = (m) })
365 
366 struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry,
367 			       struct ovl_cattr *attr);
368 int ovl_cleanup(struct inode *dir, struct dentry *dentry);
369 struct dentry *ovl_create_temp(struct dentry *workdir, struct ovl_cattr *attr);
370 
371 /* copy_up.c */
372 int ovl_copy_up(struct dentry *dentry);
373 int ovl_copy_up_flags(struct dentry *dentry, int flags);
374 int ovl_copy_xattr(struct dentry *old, struct dentry *new);
375 int ovl_set_attr(struct dentry *upper, struct kstat *stat);
376 struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper);
377 int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
378 		   struct dentry *upper);
379 
380 /* export.c */
381 extern const struct export_operations ovl_export_operations;
382