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 #include <linux/fs_struct.h>
11
12 enum { MAX_NESTED_LINKS = 8 };
13
14 #define MAXSYMLINKS 40
15
16 /* pathwalk mode */
17 #define LOOKUP_FOLLOW BIT(0) /* follow links at the end */
18 #define LOOKUP_DIRECTORY BIT(1) /* require a directory */
19 #define LOOKUP_AUTOMOUNT BIT(2) /* force terminal automount */
20 #define LOOKUP_EMPTY BIT(3) /* accept empty path [user_... only] */
21 #define LOOKUP_LINKAT_EMPTY BIT(4) /* Linkat request with empty path. */
22 #define LOOKUP_DOWN BIT(5) /* follow mounts in the starting point */
23 #define LOOKUP_MOUNTPOINT BIT(6) /* follow mounts in the end */
24 #define LOOKUP_REVAL BIT(7) /* tell ->d_revalidate() to trust no cache */
25 #define LOOKUP_RCU BIT(8) /* RCU pathwalk mode; semi-internal */
26 #define LOOKUP_CACHED BIT(9) /* Only do cached lookup */
27 #define LOOKUP_PARENT BIT(10) /* Looking up final parent in path */
28 /* 5 spare bits for pathwalk */
29
30 /* These tell filesystem methods that we are dealing with the final component... */
31 #define LOOKUP_OPEN BIT(16) /* ... in open */
32 #define LOOKUP_CREATE BIT(17) /* ... in object creation */
33 #define LOOKUP_EXCL BIT(18) /* ... in target must not exist */
34 #define LOOKUP_RENAME_TARGET BIT(19) /* ... in destination of rename() */
35 #define LOOKUP_SHARED BIT(20) /* Parent lock is held shared */
36
37 /* 3 spare bits for intent */
38
39 /* Scoping flags for lookup. */
40 #define LOOKUP_NO_SYMLINKS BIT(24) /* No symlink crossing. */
41 #define LOOKUP_NO_MAGICLINKS BIT(25) /* No nd_jump_link() crossing. */
42 #define LOOKUP_NO_XDEV BIT(26) /* No mountpoint crossing. */
43 #define LOOKUP_BENEATH BIT(27) /* No escaping from starting point. */
44 #define LOOKUP_IN_ROOT BIT(28) /* Treat dirfd as fs root. */
45 /* LOOKUP_* flags which do scope-related checks based on the dirfd. */
46 #define LOOKUP_IS_SCOPED (LOOKUP_BENEATH | LOOKUP_IN_ROOT)
47 /* 3 spare bits for scoping */
48
49 extern int path_pts(struct path *path);
50
51 extern int user_path_at(int, const char __user *, unsigned, struct path *);
52
53 extern int kern_path(const char *, unsigned, struct path *);
54 struct dentry *kern_path_parent(const char *name, struct path *parent);
55
56 extern struct dentry *start_creating_path(int, const char *, struct path *, unsigned int);
57 extern struct dentry *start_creating_user_path(int, const char __user *, struct path *, unsigned int);
58 extern void end_creating_path(const struct path *, struct dentry *);
59 extern struct dentry *start_removing_path(const char *, struct path *);
end_removing_path(const struct path * path,struct dentry * dentry)60 static inline void end_removing_path(const struct path *path , struct dentry *dentry)
61 {
62 end_creating_path(path, dentry);
63 }
64 int vfs_path_parent_lookup(struct filename *filename, unsigned int flags,
65 struct path *parent, struct qstr *last,
66 const struct path *root);
67 int vfs_path_lookup(struct dentry *, struct vfsmount *, const char *,
68 unsigned int, struct path *);
69
70 extern struct dentry *try_lookup_noperm(struct qstr *, struct dentry *);
71 extern struct dentry *lookup_noperm(struct qstr *, struct dentry *);
72 extern struct dentry *lookup_noperm_unlocked(struct qstr *, struct dentry *);
73 extern struct dentry *lookup_noperm_positive_unlocked(struct qstr *, struct dentry *);
74 struct dentry *lookup_one(const struct mnt_idmap *, struct qstr *, struct dentry *);
75 struct dentry *lookup_one_unlocked(const struct mnt_idmap *idmap,
76 struct qstr *name, struct dentry *base);
77 struct dentry *lookup_one_positive_unlocked(const struct mnt_idmap *idmap,
78 struct qstr *name,
79 struct dentry *base);
80 struct dentry *lookup_one_positive_killable(const struct mnt_idmap *idmap,
81 struct qstr *name,
82 struct dentry *base);
83
84 struct dentry *start_creating(const struct mnt_idmap *idmap, struct dentry *parent,
85 struct qstr *name);
86 struct dentry *start_removing(const struct mnt_idmap *idmap, struct dentry *parent,
87 struct qstr *name);
88 struct dentry *start_creating_killable(const struct mnt_idmap *idmap,
89 struct dentry *parent,
90 struct qstr *name);
91 struct dentry *start_removing_killable(const struct mnt_idmap *idmap,
92 struct dentry *parent,
93 struct qstr *name);
94 struct dentry *start_creating_noperm(struct dentry *parent, struct qstr *name);
95 struct dentry *start_removing_noperm(struct dentry *parent, struct qstr *name);
96 struct dentry *start_creating_dentry(struct dentry *parent,
97 struct dentry *child);
98 struct dentry *start_removing_dentry(struct dentry *parent,
99 struct dentry *child);
100
101 struct file *vfs_lookup_open(struct path *parent, struct qstr *last,
102 int open_flag, umode_t mode);
103
104 /* end_creating - finish action started with start_creating
105 * @child: dentry returned by start_creating() or vfs_mkdir()
106 *
107 * Unlock and release the child. This can be called after
108 * start_creating() whether that function succeeded or not,
109 * but it is not needed on failure.
110 *
111 * If vfs_mkdir() was called then the value returned from that function
112 * should be given for @child rather than the original dentry, as vfs_mkdir()
113 * may have provided a new dentry.
114 *
115 *
116 * If vfs_mkdir() was not called, then @child will be a valid dentry and
117 * @parent will be ignored.
118 */
end_creating(struct dentry * child)119 static inline void end_creating(struct dentry *child)
120 {
121 end_dirop(child);
122 }
123
124 /* end_creating_keep - finish action started with start_creating() and return result
125 * @child: dentry returned by start_creating() or vfs_mkdir()
126 *
127 * Unlock and return the child. This can be called after
128 * start_creating() whether that function succeeded or not,
129 * but it is not needed on failure.
130 *
131 * If vfs_mkdir() was called then the value returned from that function
132 * should be given for @child rather than the original dentry, as vfs_mkdir()
133 * may have provided a new dentry.
134 *
135 * Returns: @child, which may be a dentry or an error.
136 *
137 */
end_creating_keep(struct dentry * child)138 static inline struct dentry *end_creating_keep(struct dentry *child)
139 {
140 if (!IS_ERR(child))
141 dget(child);
142 end_dirop(child);
143 return child;
144 }
145
146 /**
147 * end_removing - finish action started with start_removing
148 * @child: dentry returned by start_removing()
149 * @parent: dentry given to start_removing()
150 *
151 * Unlock and release the child.
152 *
153 * This is identical to end_dirop(). It can be passed the result of
154 * start_removing() whether that was successful or not, but it not needed
155 * if start_removing() failed.
156 */
end_removing(struct dentry * child)157 static inline void end_removing(struct dentry *child)
158 {
159 end_dirop(child);
160 }
161
162 extern int follow_down_one(struct path *);
163 extern int follow_down(struct path *path, unsigned int flags);
164 extern int follow_up(struct path *);
165
166 int start_renaming(struct renamedata *rd, int lookup_flags,
167 struct qstr *old_last, struct qstr *new_last);
168 int start_renaming_dentry(struct renamedata *rd, int lookup_flags,
169 struct dentry *old_dentry, struct qstr *new_last);
170 int start_renaming_two_dentries(struct renamedata *rd,
171 struct dentry *old_dentry, struct dentry *new_dentry);
172 void end_renaming(struct renamedata *rd);
173
174 /**
175 * mode_strip_umask - handle vfs umask stripping
176 * @dir: parent directory of the new inode
177 * @mode: mode of the new inode to be created in @dir
178 *
179 * In most filesystems, umask stripping depends on whether or not the
180 * filesystem supports POSIX ACLs. If the filesystem doesn't support it umask
181 * stripping is done directly in here. If the filesystem does support POSIX
182 * ACLs umask stripping is deferred until the filesystem calls
183 * posix_acl_create().
184 *
185 * Some filesystems (like NFSv4) also want to avoid umask stripping by the
186 * VFS, but don't support POSIX ACLs. Those filesystems can set SB_I_NOUMASK
187 * to get this effect without declaring that they support POSIX ACLs.
188 *
189 * Returns: mode
190 */
mode_strip_umask(const struct inode * dir,umode_t mode)191 static inline umode_t __must_check mode_strip_umask(const struct inode *dir, umode_t mode)
192 {
193 if (!IS_POSIXACL(dir) && !(dir->i_sb->s_iflags & SB_I_NOUMASK))
194 mode &= ~current_umask();
195 return mode;
196 }
197
198 extern int __must_check nd_jump_link(const struct path *path);
199
nd_terminate_link(void * name,size_t len,size_t maxlen)200 static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
201 {
202 ((char *) name)[min(len, maxlen)] = '\0';
203 }
204
205 /**
206 * retry_estale - determine whether the caller should retry an operation
207 * @error: the error that would currently be returned
208 * @flags: flags being used for next lookup attempt
209 *
210 * Check to see if the error code was -ESTALE, and then determine whether
211 * to retry the call based on whether "flags" already has LOOKUP_REVAL set.
212 *
213 * Returns true if the caller should try the operation again.
214 */
215 static inline bool
retry_estale(const long error,const unsigned int flags)216 retry_estale(const long error, const unsigned int flags)
217 {
218 return unlikely(error == -ESTALE && !(flags & LOOKUP_REVAL));
219 }
220
221 #endif /* _LINUX_NAMEI_H */
222