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 */
mode_strip_umask(const struct inode * dir,umode_t mode)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
nd_terminate_link(void * name,size_t len,size_t maxlen)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
retry_estale(const long error,const unsigned int flags)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