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