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 /*
17 * Type of the last component on LOOKUP_PARENT
18 */
19 enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT};
20
21 /* pathwalk mode */
22 #define LOOKUP_FOLLOW BIT(0) /* follow links at the end */
23 #define LOOKUP_DIRECTORY BIT(1) /* require a directory */
24 #define LOOKUP_AUTOMOUNT BIT(2) /* force terminal automount */
25 #define LOOKUP_EMPTY BIT(3) /* accept empty path [user_... only] */
26 #define LOOKUP_LINKAT_EMPTY BIT(4) /* Linkat request with empty path. */
27 #define LOOKUP_DOWN BIT(5) /* follow mounts in the starting point */
28 #define LOOKUP_MOUNTPOINT BIT(6) /* follow mounts in the end */
29 #define LOOKUP_REVAL BIT(7) /* tell ->d_revalidate() to trust no cache */
30 #define LOOKUP_RCU BIT(8) /* RCU pathwalk mode; semi-internal */
31 #define LOOKUP_CACHED BIT(9) /* Only do cached lookup */
32 #define LOOKUP_PARENT BIT(10) /* Looking up final parent in path */
33 /* 5 spare bits for pathwalk */
34
35 /* These tell filesystem methods that we are dealing with the final component... */
36 #define LOOKUP_OPEN BIT(16) /* ... in open */
37 #define LOOKUP_CREATE BIT(17) /* ... in object creation */
38 #define LOOKUP_EXCL BIT(18) /* ... in target must not exist */
39 #define LOOKUP_RENAME_TARGET BIT(19) /* ... in destination of rename() */
40
41 /* 4 spare bits for intent */
42
43 /* Scoping flags for lookup. */
44 #define LOOKUP_NO_SYMLINKS BIT(24) /* No symlink crossing. */
45 #define LOOKUP_NO_MAGICLINKS BIT(25) /* No nd_jump_link() crossing. */
46 #define LOOKUP_NO_XDEV BIT(26) /* No mountpoint crossing. */
47 #define LOOKUP_BENEATH BIT(27) /* No escaping from starting point. */
48 #define LOOKUP_IN_ROOT BIT(28) /* Treat dirfd as fs root. */
49 /* LOOKUP_* flags which do scope-related checks based on the dirfd. */
50 #define LOOKUP_IS_SCOPED (LOOKUP_BENEATH | LOOKUP_IN_ROOT)
51 /* 3 spare bits for scoping */
52
53 extern int path_pts(struct path *path);
54
55 extern int user_path_at(int, const char __user *, unsigned, struct path *);
56
57 struct dentry *lookup_one_qstr_excl(const struct qstr *name,
58 struct dentry *base,
59 unsigned int flags);
60 extern int kern_path(const char *, unsigned, struct path *);
61 struct dentry *kern_path_parent(const char *name, struct path *parent);
62
63 extern struct dentry *start_creating_path(int, const char *, struct path *, unsigned int);
64 extern struct dentry *start_creating_user_path(int, const char __user *, struct path *, unsigned int);
65 extern void end_creating_path(const struct path *, struct dentry *);
66 extern struct dentry *start_removing_path(const char *, struct path *);
67 extern struct dentry *start_removing_user_path_at(int , const char __user *, struct path *);
end_removing_path(const struct path * path,struct dentry * dentry)68 static inline void end_removing_path(const struct path *path , struct dentry *dentry)
69 {
70 end_creating_path(path, dentry);
71 }
72 int vfs_path_parent_lookup(struct filename *filename, unsigned int flags,
73 struct path *parent, struct qstr *last, int *type,
74 const struct path *root);
75 int vfs_path_lookup(struct dentry *, struct vfsmount *, const char *,
76 unsigned int, struct path *);
77
78 extern struct dentry *try_lookup_noperm(struct qstr *, struct dentry *);
79 extern struct dentry *lookup_noperm(struct qstr *, struct dentry *);
80 extern struct dentry *lookup_noperm_unlocked(struct qstr *, struct dentry *);
81 extern struct dentry *lookup_noperm_positive_unlocked(struct qstr *, struct dentry *);
82 struct dentry *lookup_one(struct mnt_idmap *, struct qstr *, struct dentry *);
83 struct dentry *lookup_one_unlocked(struct mnt_idmap *idmap,
84 struct qstr *name, struct dentry *base);
85 struct dentry *lookup_one_positive_unlocked(struct mnt_idmap *idmap,
86 struct qstr *name,
87 struct dentry *base);
88 struct dentry *lookup_one_positive_killable(struct mnt_idmap *idmap,
89 struct qstr *name,
90 struct dentry *base);
91
92 struct dentry *start_creating(struct mnt_idmap *idmap, struct dentry *parent,
93 struct qstr *name);
94 struct dentry *start_removing(struct mnt_idmap *idmap, struct dentry *parent,
95 struct qstr *name);
96 struct dentry *start_creating_killable(struct mnt_idmap *idmap,
97 struct dentry *parent,
98 struct qstr *name);
99 struct dentry *start_removing_killable(struct mnt_idmap *idmap,
100 struct dentry *parent,
101 struct qstr *name);
102 struct dentry *start_creating_noperm(struct dentry *parent, struct qstr *name);
103 struct dentry *start_removing_noperm(struct dentry *parent, struct qstr *name);
104 struct dentry *start_creating_dentry(struct dentry *parent,
105 struct dentry *child);
106 struct dentry *start_removing_dentry(struct dentry *parent,
107 struct dentry *child);
108
109 /* end_creating - finish action started with start_creating
110 * @child: dentry returned by start_creating() or vfs_mkdir()
111 *
112 * Unlock and release the child. This can be called after
113 * start_creating() whether that function succeeded or not,
114 * but it is not needed on failure.
115 *
116 * If vfs_mkdir() was called then the value returned from that function
117 * should be given for @child rather than the original dentry, as vfs_mkdir()
118 * may have provided a new dentry.
119 *
120 *
121 * If vfs_mkdir() was not called, then @child will be a valid dentry and
122 * @parent will be ignored.
123 */
end_creating(struct dentry * child)124 static inline void end_creating(struct dentry *child)
125 {
126 end_dirop(child);
127 }
128
129 /* end_creating_keep - finish action started with start_creating() and return result
130 * @child: dentry returned by start_creating() or vfs_mkdir()
131 *
132 * Unlock and return the child. This can be called after
133 * start_creating() whether that function succeeded or not,
134 * but it is not needed on failure.
135 *
136 * If vfs_mkdir() was called then the value returned from that function
137 * should be given for @child rather than the original dentry, as vfs_mkdir()
138 * may have provided a new dentry.
139 *
140 * Returns: @child, which may be a dentry or an error.
141 *
142 */
end_creating_keep(struct dentry * child)143 static inline struct dentry *end_creating_keep(struct dentry *child)
144 {
145 if (!IS_ERR(child))
146 dget(child);
147 end_dirop(child);
148 return child;
149 }
150
151 /**
152 * end_removing - finish action started with start_removing
153 * @child: dentry returned by start_removing()
154 * @parent: dentry given to start_removing()
155 *
156 * Unlock and release the child.
157 *
158 * This is identical to end_dirop(). It can be passed the result of
159 * start_removing() whether that was successful or not, but it not needed
160 * if start_removing() failed.
161 */
end_removing(struct dentry * child)162 static inline void end_removing(struct dentry *child)
163 {
164 end_dirop(child);
165 }
166
167 extern int follow_down_one(struct path *);
168 extern int follow_down(struct path *path, unsigned int flags);
169 extern int follow_up(struct path *);
170
171 extern struct dentry *lock_rename(struct dentry *, struct dentry *);
172 extern struct dentry *lock_rename_child(struct dentry *, struct dentry *);
173 extern void unlock_rename(struct dentry *, struct dentry *);
174 int start_renaming(struct renamedata *rd, int lookup_flags,
175 struct qstr *old_last, struct qstr *new_last);
176 int start_renaming_dentry(struct renamedata *rd, int lookup_flags,
177 struct dentry *old_dentry, struct qstr *new_last);
178 int start_renaming_two_dentries(struct renamedata *rd,
179 struct dentry *old_dentry, struct dentry *new_dentry);
180 void end_renaming(struct renamedata *rd);
181
182 /**
183 * mode_strip_umask - handle vfs umask stripping
184 * @dir: parent directory of the new inode
185 * @mode: mode of the new inode to be created in @dir
186 *
187 * In most filesystems, umask stripping depends on whether or not the
188 * filesystem supports POSIX ACLs. If the filesystem doesn't support it umask
189 * stripping is done directly in here. If the filesystem does support POSIX
190 * ACLs umask stripping is deferred until the filesystem calls
191 * posix_acl_create().
192 *
193 * Some filesystems (like NFSv4) also want to avoid umask stripping by the
194 * VFS, but don't support POSIX ACLs. Those filesystems can set SB_I_NOUMASK
195 * to get this effect without declaring that they support POSIX ACLs.
196 *
197 * Returns: mode
198 */
mode_strip_umask(const struct inode * dir,umode_t mode)199 static inline umode_t __must_check mode_strip_umask(const struct inode *dir, umode_t mode)
200 {
201 if (!IS_POSIXACL(dir) && !(dir->i_sb->s_iflags & SB_I_NOUMASK))
202 mode &= ~current_umask();
203 return mode;
204 }
205
206 extern int __must_check nd_jump_link(const struct path *path);
207
nd_terminate_link(void * name,size_t len,size_t maxlen)208 static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
209 {
210 ((char *) name)[min(len, maxlen)] = '\0';
211 }
212
213 /**
214 * retry_estale - determine whether the caller should retry an operation
215 * @error: the error that would currently be returned
216 * @flags: flags being used for next lookup attempt
217 *
218 * Check to see if the error code was -ESTALE, and then determine whether
219 * to retry the call based on whether "flags" already has LOOKUP_REVAL set.
220 *
221 * Returns true if the caller should try the operation again.
222 */
223 static inline bool
retry_estale(const long error,const unsigned int flags)224 retry_estale(const long error, const unsigned int flags)
225 {
226 return unlikely(error == -ESTALE && !(flags & LOOKUP_REVAL));
227 }
228
229 #endif /* _LINUX_NAMEI_H */
230