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_empty(int, const char __user *, unsigned, struct path *, int *empty); 54 55 static inline int user_path_at(int dfd, const char __user *name, unsigned flags, 56 struct path *path) 57 { 58 return user_path_at_empty(dfd, name, flags, path, NULL); 59 } 60 61 struct dentry *lookup_one_qstr_excl(const struct qstr *name, 62 struct dentry *base, 63 unsigned int flags); 64 extern int kern_path(const char *, unsigned, struct path *); 65 66 extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int); 67 extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int); 68 extern void done_path_create(struct path *, struct dentry *); 69 extern struct dentry *kern_path_locked(const char *, struct path *); 70 extern struct dentry *user_path_locked_at(int , const char __user *, struct path *); 71 int vfs_path_parent_lookup(struct filename *filename, unsigned int flags, 72 struct path *parent, struct qstr *last, int *type, 73 const struct path *root); 74 int vfs_path_lookup(struct dentry *, struct vfsmount *, const char *, 75 unsigned int, struct path *); 76 77 extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int); 78 extern struct dentry *lookup_one_len(const char *, struct dentry *, int); 79 extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int); 80 extern struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int); 81 struct dentry *lookup_one(struct mnt_idmap *, const char *, struct dentry *, int); 82 struct dentry *lookup_one_unlocked(struct mnt_idmap *idmap, 83 const char *name, struct dentry *base, 84 int len); 85 struct dentry *lookup_one_positive_unlocked(struct mnt_idmap *idmap, 86 const char *name, 87 struct dentry *base, int len); 88 89 extern int follow_down_one(struct path *); 90 extern int follow_down(struct path *path, unsigned int flags); 91 extern int follow_up(struct path *); 92 93 extern struct dentry *lock_rename(struct dentry *, struct dentry *); 94 extern struct dentry *lock_rename_child(struct dentry *, struct dentry *); 95 extern void unlock_rename(struct dentry *, struct dentry *); 96 97 /** 98 * mode_strip_umask - handle vfs umask stripping 99 * @dir: parent directory of the new inode 100 * @mode: mode of the new inode to be created in @dir 101 * 102 * In most filesystems, umask stripping depends on whether or not the 103 * filesystem supports POSIX ACLs. If the filesystem doesn't support it umask 104 * stripping is done directly in here. If the filesystem does support POSIX 105 * ACLs umask stripping is deferred until the filesystem calls 106 * posix_acl_create(). 107 * 108 * Some filesystems (like NFSv4) also want to avoid umask stripping by the 109 * VFS, but don't support POSIX ACLs. Those filesystems can set SB_I_NOUMASK 110 * to get this effect without declaring that they support POSIX ACLs. 111 * 112 * Returns: mode 113 */ 114 static inline umode_t __must_check mode_strip_umask(const struct inode *dir, umode_t mode) 115 { 116 if (!IS_POSIXACL(dir) && !(dir->i_sb->s_iflags & SB_I_NOUMASK)) 117 mode &= ~current_umask(); 118 return mode; 119 } 120 121 extern int __must_check nd_jump_link(const struct path *path); 122 123 static inline void nd_terminate_link(void *name, size_t len, size_t maxlen) 124 { 125 ((char *) name)[min(len, maxlen)] = '\0'; 126 } 127 128 /** 129 * retry_estale - determine whether the caller should retry an operation 130 * @error: the error that would currently be returned 131 * @flags: flags being used for next lookup attempt 132 * 133 * Check to see if the error code was -ESTALE, and then determine whether 134 * to retry the call based on whether "flags" already has LOOKUP_REVAL set. 135 * 136 * Returns true if the caller should try the operation again. 137 */ 138 static inline bool 139 retry_estale(const long error, const unsigned int flags) 140 { 141 return unlikely(error == -ESTALE && !(flags & LOOKUP_REVAL)); 142 } 143 144 #endif /* _LINUX_NAMEI_H */ 145