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 mnt_idmap *, const char *, struct dentry *, int);
72  struct dentry *lookup_one_unlocked(struct mnt_idmap *idmap,
73  				   const char *name, struct dentry *base,
74  				   int len);
75  struct dentry *lookup_one_positive_unlocked(struct mnt_idmap *idmap,
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 *path, unsigned int flags);
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