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  #define LOOKUP_LINKAT_EMPTY	0x400000 /* Linkat request with empty path. */
48  /* LOOKUP_* flags which do scope-related checks based on the dirfd. */
49  #define LOOKUP_IS_SCOPED (LOOKUP_BENEATH | LOOKUP_IN_ROOT)
50  
51  extern int path_pts(struct path *path);
52  
53  extern int user_path_at(int, const char __user *, unsigned, struct path *);
54  
55  struct dentry *lookup_one_qstr_excl(const struct qstr *name,
56  				    struct dentry *base,
57  				    unsigned int flags);
58  extern int kern_path(const char *, unsigned, struct path *);
59  
60  extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int);
61  extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
62  extern void done_path_create(struct path *, struct dentry *);
63  extern struct dentry *kern_path_locked(const char *, struct path *);
64  extern struct dentry *user_path_locked_at(int , const char __user *, struct path *);
65  int vfs_path_parent_lookup(struct filename *filename, unsigned int flags,
66  			   struct path *parent, struct qstr *last, int *type,
67  			   const struct path *root);
68  int vfs_path_lookup(struct dentry *, struct vfsmount *, const char *,
69  		    unsigned int, struct path *);
70  
71  extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int);
72  extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
73  extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
74  extern struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int);
75  struct dentry *lookup_one(struct mnt_idmap *, const char *, struct dentry *, int);
76  struct dentry *lookup_one_unlocked(struct mnt_idmap *idmap,
77  				   const char *name, struct dentry *base,
78  				   int len);
79  struct dentry *lookup_one_positive_unlocked(struct mnt_idmap *idmap,
80  					    const char *name,
81  					    struct dentry *base, int len);
82  
83  extern int follow_down_one(struct path *);
84  extern int follow_down(struct path *path, unsigned int flags);
85  extern int follow_up(struct path *);
86  
87  extern struct dentry *lock_rename(struct dentry *, struct dentry *);
88  extern struct dentry *lock_rename_child(struct dentry *, struct dentry *);
89  extern void unlock_rename(struct dentry *, struct dentry *);
90  
91  /**
92   * mode_strip_umask - handle vfs umask stripping
93   * @dir:	parent directory of the new inode
94   * @mode:	mode of the new inode to be created in @dir
95   *
96   * In most filesystems, umask stripping depends on whether or not the
97   * filesystem supports POSIX ACLs. If the filesystem doesn't support it umask
98   * stripping is done directly in here. If the filesystem does support POSIX
99   * ACLs umask stripping is deferred until the filesystem calls
100   * posix_acl_create().
101   *
102   * Some filesystems (like NFSv4) also want to avoid umask stripping by the
103   * VFS, but don't support POSIX ACLs. Those filesystems can set SB_I_NOUMASK
104   * to get this effect without declaring that they support POSIX ACLs.
105   *
106   * Returns: mode
107   */
mode_strip_umask(const struct inode * dir,umode_t mode)108  static inline umode_t __must_check mode_strip_umask(const struct inode *dir, umode_t mode)
109  {
110  	if (!IS_POSIXACL(dir) && !(dir->i_sb->s_iflags & SB_I_NOUMASK))
111  		mode &= ~current_umask();
112  	return mode;
113  }
114  
115  extern int __must_check nd_jump_link(const struct path *path);
116  
nd_terminate_link(void * name,size_t len,size_t maxlen)117  static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
118  {
119  	((char *) name)[min(len, maxlen)] = '\0';
120  }
121  
122  /**
123   * retry_estale - determine whether the caller should retry an operation
124   * @error: the error that would currently be returned
125   * @flags: flags being used for next lookup attempt
126   *
127   * Check to see if the error code was -ESTALE, and then determine whether
128   * to retry the call based on whether "flags" already has LOOKUP_REVAL set.
129   *
130   * Returns true if the caller should try the operation again.
131   */
132  static inline bool
retry_estale(const long error,const unsigned int flags)133  retry_estale(const long error, const unsigned int flags)
134  {
135  	return unlikely(error == -ESTALE && !(flags & LOOKUP_REVAL));
136  }
137  
138  #endif /* _LINUX_NAMEI_H */
139