include/linux/namei.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_NAMEI_H
   3 #define _LINUX_NAMEI_H
   4
   5 #include <linux/kernel.h>
   6 #include <linux/path.h>
   7 #include <linux/fcntl.h>
   8 #include <linux/errno.h>
   9
  10 enum { MAX_NESTED_LINKS = 8 };
  11
  12 #define MAXSYMLINKS 40
  13
  14 /*
  15  * Type of the last component on LOOKUP_PARENT
  16  */
  17 enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
  18
  19 /*
  20  * The bitmask for a lookup event:
  21  *  - follow links at the end
  22  *  - require a directory
  23  *  - ending slashes ok even for nonexistent files
  24  *  - internal "there are more path components" flag
  25  *  - dentry cache is untrusted; force a real lookup
  26  *  - suppress terminal automount
  27  *  - skip revalidation
  28  *  - don't fetch xattrs on audit_inode
  29  */
  30 #define LOOKUP_FOLLOW           0x0001
  31 #define LOOKUP_DIRECTORY        0x0002
  32 #define LOOKUP_AUTOMOUNT        0x0004
  33
  34 #define LOOKUP_PARENT           0x0010
  35 #define LOOKUP_REVAL            0x0020
  36 #define LOOKUP_RCU              0x0040
  37 #define LOOKUP_NO_REVAL         0x0080
  38 #define LOOKUP_NO_EVAL          0x0100
  39
  40 /*
  41  * Intent data
  42  */
  43 #define LOOKUP_OPEN             0x0100
  44 #define LOOKUP_CREATE           0x0200
  45 #define LOOKUP_EXCL             0x0400
  46 #define LOOKUP_RENAME_TARGET    0x0800
  47
  48 #define LOOKUP_JUMPED           0x1000
  49 #define LOOKUP_ROOT             0x2000
  50 #define LOOKUP_EMPTY            0x4000
  51 #define LOOKUP_DOWN             0x8000
  52
  53 extern int path_pts(struct path *path);
  54
  55 extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty);
  56
  57 static inline int user_path_at(int dfd, const char __user *name, unsigned flags,
  58                  struct path *path)
  59 {
  60         return user_path_at_empty(dfd, name, flags, path, NULL);
  61 }
  62
  63 static inline int user_path(const char __user *name, struct path *path)
  64 {
  65         return user_path_at_empty(AT_FDCWD, name, LOOKUP_FOLLOW, path, NULL);
  66 }
  67
  68 static inline int user_lpath(const char __user *name, struct path *path)
  69 {
  70         return user_path_at_empty(AT_FDCWD, name, 0, path, NULL);
  71 }
  72
  73 static inline int user_path_dir(const char __user *name, struct path *path)
  74 {
  75         return user_path_at_empty(AT_FDCWD, name,
  76                                   LOOKUP_FOLLOW | LOOKUP_DIRECTORY, path, NULL);
  77 }
  78
  79 extern int kern_path(const char *, unsigned, struct path *);
  80
  81 extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int);
  82 extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
  83 extern void done_path_create(struct path *, struct dentry *);
  84 extern struct dentry *kern_path_locked(const char *, struct path *);
  85 extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);
  86
  87 extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int);
  88 extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
  89 extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
  90
  91 extern int follow_down_one(struct path *);
  92 extern int follow_down(struct path *);
  93 extern int follow_up(struct path *);
  94
  95 extern struct dentry *lock_rename(struct dentry *, struct dentry *);
  96 extern void unlock_rename(struct dentry *, struct dentry *);
  97
  98 extern void nd_jump_link(struct path *path);
  99
 100 static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
 101 {
 102         ((char *) name)[min(len, maxlen)] = '\0';
 103 }
 104
 105 /**
 106  * retry_estale - determine whether the caller should retry an operation
 107  * @error: the error that would currently be returned
 108  * @flags: flags being used for next lookup attempt
 109  *
 110  * Check to see if the error code was -ESTALE, and then determine whether
 111  * to retry the call based on whether "flags" already has LOOKUP_REVAL set.
 112  *
 113  * Returns true if the caller should try the operation again.
 114  */
 115 static inline bool
 116 retry_estale(const long error, const unsigned int flags)
 117 {
 118         return error == -ESTALE && !(flags & LOOKUP_REVAL);
 119 }
 120
 121 #endif /* _LINUX_NAMEI_H */