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
11 enum { MAX_NESTED_LINKS = 8 };
12
13 #define MAXSYMLINKS 40
14
15 /*
16 * Type of the last component on LOOKUP_PARENT
17 */
18 enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT};
19
20 /* pathwalk mode */
21 #define LOOKUP_FOLLOW 0x0001 /* follow links at the end */
22 #define LOOKUP_DIRECTORY 0x0002 /* require a directory */
23 #define LOOKUP_AUTOMOUNT 0x0004 /* force terminal automount */
24 #define LOOKUP_EMPTY 0x4000 /* accept empty path [user_... only] */
25 #define LOOKUP_DOWN 0x8000 /* follow mounts in the starting point */
26 #define LOOKUP_MOUNTPOINT 0x0080 /* follow mounts in the end */
27
28 #define LOOKUP_REVAL 0x0020 /* tell ->d_revalidate() to trust no cache */
29 #define LOOKUP_RCU 0x0040 /* RCU pathwalk mode; semi-internal */
30
31 /* These tell filesystem methods that we are dealing with the final component... */
32 #define LOOKUP_OPEN 0x0100 /* ... in open */
33 #define LOOKUP_CREATE 0x0200 /* ... in object creation */
34 #define LOOKUP_EXCL 0x0400 /* ... in exclusive creation */
35 #define LOOKUP_RENAME_TARGET 0x0800 /* ... in destination of rename() */
36
37 /* internal use only */
38 #define LOOKUP_PARENT 0x0010
39
40 /* Scoping flags for lookup. */
41 #define LOOKUP_NO_SYMLINKS 0x010000 /* No symlink crossing. */
42 #define LOOKUP_NO_MAGICLINKS 0x020000 /* No nd_jump_link() crossing. */
43 #define LOOKUP_NO_XDEV 0x040000 /* No mountpoint crossing. */
44 #define LOOKUP_BENEATH 0x080000 /* No escaping from starting point. */
45 #define LOOKUP_IN_ROOT 0x100000 /* Treat dirfd as fs root. */
46 #define LOOKUP_CACHED 0x200000 /* Only do cached lookup */
47 /* LOOKUP_* flags which do scope-related checks based on the dirfd. */
48 #define LOOKUP_IS_SCOPED (LOOKUP_BENEATH | LOOKUP_IN_ROOT)
49
50 extern int path_pts(struct path *path);
51
52 extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty);
53
user_path_at(int dfd,const char __user * name,unsigned flags,struct path * path)54 static inline int user_path_at(int dfd, const char __user *name, unsigned flags,
55 struct path *path)
56 {
57 return user_path_at_empty(dfd, name, flags, path, NULL);
58 }
59
60 extern int kern_path(const char *, unsigned, struct path *);
61
62 extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int);
63 extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
64 extern void done_path_create(struct path *, struct dentry *);
65 extern struct dentry *kern_path_locked(const char *, struct path *);
66
67 extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int);
68 extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
69 extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
70 extern struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int);
71 struct dentry *lookup_one(struct user_namespace *, const char *, struct dentry *, int);
72 struct dentry *lookup_one_unlocked(struct user_namespace *mnt_userns,
73 const char *name, struct dentry *base,
74 int len);
75 struct dentry *lookup_one_positive_unlocked(struct user_namespace *mnt_userns,
76 const char *name,
77 struct dentry *base, int len);
78
79 extern int follow_down_one(struct path *);
80 extern int follow_down(struct path *);
81 extern int follow_up(struct path *);
82
83 extern struct dentry *lock_rename(struct dentry *, struct dentry *);
84 extern void unlock_rename(struct dentry *, struct dentry *);
85
86 extern int __must_check nd_jump_link(const struct path *path);
87
nd_terminate_link(void * name,size_t len,size_t maxlen)88 static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
89 {
90 ((char *) name)[min(len, maxlen)] = '\0';
91 }
92
93 /**
94 * retry_estale - determine whether the caller should retry an operation
95 * @error: the error that would currently be returned
96 * @flags: flags being used for next lookup attempt
97 *
98 * Check to see if the error code was -ESTALE, and then determine whether
99 * to retry the call based on whether "flags" already has LOOKUP_REVAL set.
100 *
101 * Returns true if the caller should try the operation again.
102 */
103 static inline bool
retry_estale(const long error,const unsigned int flags)104 retry_estale(const long error, const unsigned int flags)
105 {
106 return error == -ESTALE && !(flags & LOOKUP_REVAL);
107 }
108
109 #endif /* _LINUX_NAMEI_H */
110