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 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 struct dentry *lookup_one_qstr_excl(const struct qstr *name, 61 struct dentry *base, 62 unsigned int flags); 63 extern int kern_path(const char *, unsigned, struct path *); 64 65 extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int); 66 extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int); 67 extern void done_path_create(struct path *, struct dentry *); 68 extern struct dentry *kern_path_locked(const char *, struct path *); 69 int vfs_path_parent_lookup(struct filename *filename, unsigned int flags, 70 struct path *parent, struct qstr *last, int *type, 71 const struct path *root); 72 int vfs_path_lookup(struct dentry *, struct vfsmount *, const char *, 73 unsigned int, struct path *); 74 75 extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int); 76 extern struct dentry *lookup_one_len(const char *, struct dentry *, int); 77 extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int); 78 extern struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int); 79 struct dentry *lookup_one(struct mnt_idmap *, const char *, struct dentry *, int); 80 struct dentry *lookup_one_unlocked(struct mnt_idmap *idmap, 81 const char *name, struct dentry *base, 82 int len); 83 struct dentry *lookup_one_positive_unlocked(struct mnt_idmap *idmap, 84 const char *name, 85 struct dentry *base, int len); 86 87 extern int follow_down_one(struct path *); 88 extern int follow_down(struct path *path, unsigned int flags); 89 extern int follow_up(struct path *); 90 91 extern struct dentry *lock_rename(struct dentry *, struct dentry *); 92 extern struct dentry *lock_rename_child(struct dentry *, struct dentry *); 93 extern void unlock_rename(struct dentry *, struct dentry *); 94 95 /** 96 * mode_strip_umask - handle vfs umask stripping 97 * @dir: parent directory of the new inode 98 * @mode: mode of the new inode to be created in @dir 99 * 100 * In most filesystems, umask stripping depends on whether or not the 101 * filesystem supports POSIX ACLs. If the filesystem doesn't support it umask 102 * stripping is done directly in here. If the filesystem does support POSIX 103 * ACLs umask stripping is deferred until the filesystem calls 104 * posix_acl_create(). 105 * 106 * Some filesystems (like NFSv4) also want to avoid umask stripping by the 107 * VFS, but don't support POSIX ACLs. Those filesystems can set SB_I_NOUMASK 108 * to get this effect without declaring that they support POSIX ACLs. 109 * 110 * Returns: mode 111 */ 112 static inline umode_t __must_check mode_strip_umask(const struct inode *dir, umode_t mode) 113 { 114 if (!IS_POSIXACL(dir) && !(dir->i_sb->s_iflags & SB_I_NOUMASK)) 115 mode &= ~current_umask(); 116 return mode; 117 } 118 119 extern int __must_check nd_jump_link(const struct path *path); 120 121 static inline void nd_terminate_link(void *name, size_t len, size_t maxlen) 122 { 123 ((char *) name)[min(len, maxlen)] = '\0'; 124 } 125 126 /** 127 * retry_estale - determine whether the caller should retry an operation 128 * @error: the error that would currently be returned 129 * @flags: flags being used for next lookup attempt 130 * 131 * Check to see if the error code was -ESTALE, and then determine whether 132 * to retry the call based on whether "flags" already has LOOKUP_REVAL set. 133 * 134 * Returns true if the caller should try the operation again. 135 */ 136 static inline bool 137 retry_estale(const long error, const unsigned int flags) 138 { 139 return unlikely(error == -ESTALE && !(flags & LOOKUP_REVAL)); 140 } 141 142 #endif /* _LINUX_NAMEI_H */ 143