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 BIT(0) /* follow links at the end */ 22 #define LOOKUP_DIRECTORY BIT(1) /* require a directory */ 23 #define LOOKUP_AUTOMOUNT BIT(2) /* force terminal automount */ 24 #define LOOKUP_EMPTY BIT(3) /* accept empty path [user_... only] */ 25 #define LOOKUP_LINKAT_EMPTY BIT(4) /* Linkat request with empty path. */ 26 #define LOOKUP_DOWN BIT(5) /* follow mounts in the starting point */ 27 #define LOOKUP_MOUNTPOINT BIT(6) /* follow mounts in the end */ 28 #define LOOKUP_REVAL BIT(7) /* tell ->d_revalidate() to trust no cache */ 29 #define LOOKUP_RCU BIT(8) /* RCU pathwalk mode; semi-internal */ 30 #define LOOKUP_CACHED BIT(9) /* Only do cached lookup */ 31 #define LOOKUP_PARENT BIT(10) /* Looking up final parent in path */ 32 /* 5 spare bits for pathwalk */ 33 34 /* These tell filesystem methods that we are dealing with the final component... */ 35 #define LOOKUP_OPEN BIT(16) /* ... in open */ 36 #define LOOKUP_CREATE BIT(17) /* ... in object creation */ 37 #define LOOKUP_EXCL BIT(18) /* ... in target must not exist */ 38 #define LOOKUP_RENAME_TARGET BIT(19) /* ... in destination of rename() */ 39 40 /* 4 spare bits for intent */ 41 42 /* Scoping flags for lookup. */ 43 #define LOOKUP_NO_SYMLINKS BIT(24) /* No symlink crossing. */ 44 #define LOOKUP_NO_MAGICLINKS BIT(25) /* No nd_jump_link() crossing. */ 45 #define LOOKUP_NO_XDEV BIT(26) /* No mountpoint crossing. */ 46 #define LOOKUP_BENEATH BIT(27) /* No escaping from starting point. */ 47 #define LOOKUP_IN_ROOT BIT(28) /* Treat dirfd as fs root. */ 48 /* LOOKUP_* flags which do scope-related checks based on the dirfd. */ 49 #define LOOKUP_IS_SCOPED (LOOKUP_BENEATH | LOOKUP_IN_ROOT) 50 /* 3 spare bits for scoping */ 51 52 extern int path_pts(struct path *path); 53 54 extern int user_path_at(int, const char __user *, unsigned, struct path *); 55 56 struct dentry *lookup_one_qstr_excl(const struct qstr *name, 57 struct dentry *base, 58 unsigned int flags); 59 extern int kern_path(const char *, unsigned, struct path *); 60 61 extern struct dentry *kern_path_create(int, const char *, struct path *, unsigned int); 62 extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int); 63 extern void done_path_create(struct path *, struct dentry *); 64 extern struct dentry *kern_path_locked(const char *, struct path *); 65 extern struct dentry *kern_path_locked_negative(const char *, struct path *); 66 extern struct dentry *user_path_locked_at(int , const char __user *, struct path *); 67 int vfs_path_parent_lookup(struct filename *filename, unsigned int flags, 68 struct path *parent, struct qstr *last, int *type, 69 const struct path *root); 70 int vfs_path_lookup(struct dentry *, struct vfsmount *, const char *, 71 unsigned int, struct path *); 72 73 extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int); 74 extern struct dentry *lookup_one_len(const char *, struct dentry *, int); 75 extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int); 76 extern struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int); 77 struct dentry *lookup_one(struct mnt_idmap *, const char *, struct dentry *, int); 78 struct dentry *lookup_one_unlocked(struct mnt_idmap *idmap, 79 const char *name, struct dentry *base, 80 int len); 81 struct dentry *lookup_one_positive_unlocked(struct mnt_idmap *idmap, 82 const char *name, 83 struct dentry *base, int len); 84 85 extern int follow_down_one(struct path *); 86 extern int follow_down(struct path *path, unsigned int flags); 87 extern int follow_up(struct path *); 88 89 extern struct dentry *lock_rename(struct dentry *, struct dentry *); 90 extern struct dentry *lock_rename_child(struct dentry *, struct dentry *); 91 extern void unlock_rename(struct dentry *, struct dentry *); 92 93 /** 94 * mode_strip_umask - handle vfs umask stripping 95 * @dir: parent directory of the new inode 96 * @mode: mode of the new inode to be created in @dir 97 * 98 * In most filesystems, umask stripping depends on whether or not the 99 * filesystem supports POSIX ACLs. If the filesystem doesn't support it umask 100 * stripping is done directly in here. If the filesystem does support POSIX 101 * ACLs umask stripping is deferred until the filesystem calls 102 * posix_acl_create(). 103 * 104 * Some filesystems (like NFSv4) also want to avoid umask stripping by the 105 * VFS, but don't support POSIX ACLs. Those filesystems can set SB_I_NOUMASK 106 * to get this effect without declaring that they support POSIX ACLs. 107 * 108 * Returns: mode 109 */ 110 static inline umode_t __must_check mode_strip_umask(const struct inode *dir, umode_t mode) 111 { 112 if (!IS_POSIXACL(dir) && !(dir->i_sb->s_iflags & SB_I_NOUMASK)) 113 mode &= ~current_umask(); 114 return mode; 115 } 116 117 extern int __must_check nd_jump_link(const struct path *path); 118 119 static inline void nd_terminate_link(void *name, size_t len, size_t maxlen) 120 { 121 ((char *) name)[min(len, maxlen)] = '\0'; 122 } 123 124 /** 125 * retry_estale - determine whether the caller should retry an operation 126 * @error: the error that would currently be returned 127 * @flags: flags being used for next lookup attempt 128 * 129 * Check to see if the error code was -ESTALE, and then determine whether 130 * to retry the call based on whether "flags" already has LOOKUP_REVAL set. 131 * 132 * Returns true if the caller should try the operation again. 133 */ 134 static inline bool 135 retry_estale(const long error, const unsigned int flags) 136 { 137 return unlikely(error == -ESTALE && !(flags & LOOKUP_REVAL)); 138 } 139 140 #endif /* _LINUX_NAMEI_H */ 141