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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_NAMEI_H
3#define _LINUX_NAMEI_H
4
5#include <linux/fs.h>
6#include <linux/kernel.h>
7#include <linux/path.h>
8#include <linux/fcntl.h>
9#include <linux/errno.h>
10#include <linux/fs_struct.h>
11
12enum { MAX_NESTED_LINKS = 8 };
13
14#define MAXSYMLINKS 40
15
16/*
17 * Type of the last component on LOOKUP_PARENT
18 */
19enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT};
20
21/* pathwalk mode */
22#define LOOKUP_FOLLOW BIT(0) /* follow links at the end */
23#define LOOKUP_DIRECTORY BIT(1) /* require a directory */
24#define LOOKUP_AUTOMOUNT BIT(2) /* force terminal automount */
25#define LOOKUP_EMPTY BIT(3) /* accept empty path [user_... only] */
26#define LOOKUP_LINKAT_EMPTY BIT(4) /* Linkat request with empty path. */
27#define LOOKUP_DOWN BIT(5) /* follow mounts in the starting point */
28#define LOOKUP_MOUNTPOINT BIT(6) /* follow mounts in the end */
29#define LOOKUP_REVAL BIT(7) /* tell ->d_revalidate() to trust no cache */
30#define LOOKUP_RCU BIT(8) /* RCU pathwalk mode; semi-internal */
31#define LOOKUP_CACHED BIT(9) /* Only do cached lookup */
32#define LOOKUP_PARENT BIT(10) /* Looking up final parent in path */
33/* 5 spare bits for pathwalk */
34
35/* These tell filesystem methods that we are dealing with the final component... */
36#define LOOKUP_OPEN BIT(16) /* ... in open */
37#define LOOKUP_CREATE BIT(17) /* ... in object creation */
38#define LOOKUP_EXCL BIT(18) /* ... in target must not exist */
39#define LOOKUP_RENAME_TARGET BIT(19) /* ... in destination of rename() */
40
41/* 4 spare bits for intent */
42
43/* Scoping flags for lookup. */
44#define LOOKUP_NO_SYMLINKS BIT(24) /* No symlink crossing. */
45#define LOOKUP_NO_MAGICLINKS BIT(25) /* No nd_jump_link() crossing. */
46#define LOOKUP_NO_XDEV BIT(26) /* No mountpoint crossing. */
47#define LOOKUP_BENEATH BIT(27) /* No escaping from starting point. */
48#define LOOKUP_IN_ROOT BIT(28) /* Treat dirfd as fs root. */
49/* LOOKUP_* flags which do scope-related checks based on the dirfd. */
50#define LOOKUP_IS_SCOPED (LOOKUP_BENEATH | LOOKUP_IN_ROOT)
51/* 3 spare bits for scoping */
52
53extern int path_pts(struct path *path);
54
55extern int user_path_at(int, const char __user *, unsigned, struct path *);
56
57struct dentry *lookup_one_qstr_excl(const struct qstr *name,
58 struct dentry *base,
59 unsigned int flags);
60extern int kern_path(const char *, unsigned, struct path *);
61struct dentry *kern_path_parent(const char *name, struct path *parent);
62
63extern struct dentry *start_creating_path(int, const char *, struct path *, unsigned int);
64extern struct dentry *start_creating_user_path(int, const char __user *, struct path *, unsigned int);
65extern void end_creating_path(const struct path *, struct dentry *);
66extern struct dentry *start_removing_path(const char *, struct path *);
67extern struct dentry *start_removing_user_path_at(int , const char __user *, struct path *);
68static inline void end_removing_path(const struct path *path , struct dentry *dentry)
69{
70 end_creating_path(path, dentry);
71}
72int vfs_path_parent_lookup(struct filename *filename, unsigned int flags,
73 struct path *parent, struct qstr *last, int *type,
74 const struct path *root);
75int vfs_path_lookup(struct dentry *, struct vfsmount *, const char *,
76 unsigned int, struct path *);
77
78extern struct dentry *try_lookup_noperm(struct qstr *, struct dentry *);
79extern struct dentry *lookup_noperm(struct qstr *, struct dentry *);
80extern struct dentry *lookup_noperm_unlocked(struct qstr *, struct dentry *);
81extern struct dentry *lookup_noperm_positive_unlocked(struct qstr *, struct dentry *);
82struct dentry *lookup_one(struct mnt_idmap *, struct qstr *, struct dentry *);
83struct dentry *lookup_one_unlocked(struct mnt_idmap *idmap,
84 struct qstr *name, struct dentry *base);
85struct dentry *lookup_one_positive_unlocked(struct mnt_idmap *idmap,
86 struct qstr *name,
87 struct dentry *base);
88struct dentry *lookup_one_positive_killable(struct mnt_idmap *idmap,
89 struct qstr *name,
90 struct dentry *base);
91
92struct dentry *start_creating(struct mnt_idmap *idmap, struct dentry *parent,
93 struct qstr *name);
94struct dentry *start_removing(struct mnt_idmap *idmap, struct dentry *parent,
95 struct qstr *name);
96struct dentry *start_creating_killable(struct mnt_idmap *idmap,
97 struct dentry *parent,
98 struct qstr *name);
99struct dentry *start_removing_killable(struct mnt_idmap *idmap,
100 struct dentry *parent,
101 struct qstr *name);
102struct dentry *start_creating_noperm(struct dentry *parent, struct qstr *name);
103struct dentry *start_removing_noperm(struct dentry *parent, struct qstr *name);
104struct dentry *start_creating_dentry(struct dentry *parent,
105 struct dentry *child);
106struct dentry *start_removing_dentry(struct dentry *parent,
107 struct dentry *child);
108
109/* end_creating - finish action started with start_creating
110 * @child: dentry returned by start_creating() or vfs_mkdir()
111 *
112 * Unlock and release the child. This can be called after
113 * start_creating() whether that function succeeded or not,
114 * but it is not needed on failure.
115 *
116 * If vfs_mkdir() was called then the value returned from that function
117 * should be given for @child rather than the original dentry, as vfs_mkdir()
118 * may have provided a new dentry.
119 *
120 *
121 * If vfs_mkdir() was not called, then @child will be a valid dentry and
122 * @parent will be ignored.
123 */
124static inline void end_creating(struct dentry *child)
125{
126 end_dirop(de: child);
127}
128
129/* end_creating_keep - finish action started with start_creating() and return result
130 * @child: dentry returned by start_creating() or vfs_mkdir()
131 *
132 * Unlock and return the child. This can be called after
133 * start_creating() whether that function succeeded or not,
134 * but it is not needed on failure.
135 *
136 * If vfs_mkdir() was called then the value returned from that function
137 * should be given for @child rather than the original dentry, as vfs_mkdir()
138 * may have provided a new dentry.
139 *
140 * Returns: @child, which may be a dentry or an error.
141 *
142 */
143static inline struct dentry *end_creating_keep(struct dentry *child)
144{
145 if (!IS_ERR(ptr: child))
146 dget(dentry: child);
147 end_dirop(de: child);
148 return child;
149}
150
151/**
152 * end_removing - finish action started with start_removing
153 * @child: dentry returned by start_removing()
154 * @parent: dentry given to start_removing()
155 *
156 * Unlock and release the child.
157 *
158 * This is identical to end_dirop(). It can be passed the result of
159 * start_removing() whether that was successful or not, but it not needed
160 * if start_removing() failed.
161 */
162static inline void end_removing(struct dentry *child)
163{
164 end_dirop(de: child);
165}
166
167extern int follow_down_one(struct path *);
168extern int follow_down(struct path *path, unsigned int flags);
169extern int follow_up(struct path *);
170
171extern struct dentry *lock_rename(struct dentry *, struct dentry *);
172extern struct dentry *lock_rename_child(struct dentry *, struct dentry *);
173extern void unlock_rename(struct dentry *, struct dentry *);
174int start_renaming(struct renamedata *rd, int lookup_flags,
175 struct qstr *old_last, struct qstr *new_last);
176int start_renaming_dentry(struct renamedata *rd, int lookup_flags,
177 struct dentry *old_dentry, struct qstr *new_last);
178int start_renaming_two_dentries(struct renamedata *rd,
179 struct dentry *old_dentry, struct dentry *new_dentry);
180void end_renaming(struct renamedata *rd);
181
182/**
183 * mode_strip_umask - handle vfs umask stripping
184 * @dir: parent directory of the new inode
185 * @mode: mode of the new inode to be created in @dir
186 *
187 * In most filesystems, umask stripping depends on whether or not the
188 * filesystem supports POSIX ACLs. If the filesystem doesn't support it umask
189 * stripping is done directly in here. If the filesystem does support POSIX
190 * ACLs umask stripping is deferred until the filesystem calls
191 * posix_acl_create().
192 *
193 * Some filesystems (like NFSv4) also want to avoid umask stripping by the
194 * VFS, but don't support POSIX ACLs. Those filesystems can set SB_I_NOUMASK
195 * to get this effect without declaring that they support POSIX ACLs.
196 *
197 * Returns: mode
198 */
199static inline umode_t __must_check mode_strip_umask(const struct inode *dir, umode_t mode)
200{
201 if (!IS_POSIXACL(dir) && !(dir->i_sb->s_iflags & SB_I_NOUMASK))
202 mode &= ~current_umask();
203 return mode;
204}
205
206extern int __must_check nd_jump_link(const struct path *path);
207
208static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
209{
210 ((char *) name)[min(len, maxlen)] = '\0';
211}
212
213/**
214 * retry_estale - determine whether the caller should retry an operation
215 * @error: the error that would currently be returned
216 * @flags: flags being used for next lookup attempt
217 *
218 * Check to see if the error code was -ESTALE, and then determine whether
219 * to retry the call based on whether "flags" already has LOOKUP_REVAL set.
220 *
221 * Returns true if the caller should try the operation again.
222 */
223static inline bool
224retry_estale(const long error, const unsigned int flags)
225{
226 return unlikely(error == -ESTALE && !(flags & LOOKUP_REVAL));
227}
228
229#endif /* _LINUX_NAMEI_H */
230

source code of linux/include/linux/namei.h