1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_MNT_IDMAPPING_H
3 #define _LINUX_MNT_IDMAPPING_H
5 #include <linux/types.h>
6 #include <linux/uidgid.h>
11 extern struct mnt_idmap nop_mnt_idmap;
12 extern struct user_namespace init_user_ns;
22 static_assert(sizeof(vfsuid_t) == sizeof(kuid_t));
23 static_assert(sizeof(vfsgid_t) == sizeof(kgid_t));
24 static_assert(offsetof(vfsuid_t, val) == offsetof(kuid_t, val));
25 static_assert(offsetof(vfsgid_t, val) == offsetof(kgid_t, val));
27 #ifdef CONFIG_MULTIUSER
28 static inline uid_t __vfsuid_val(vfsuid_t uid)
33 static inline gid_t __vfsgid_val(vfsgid_t gid)
38 static inline uid_t __vfsuid_val(vfsuid_t uid)
43 static inline gid_t __vfsgid_val(vfsgid_t gid)
49 static inline bool vfsuid_valid(vfsuid_t uid)
51 return __vfsuid_val(uid) != (uid_t)-1;
54 static inline bool vfsgid_valid(vfsgid_t gid)
56 return __vfsgid_val(gid) != (gid_t)-1;
59 static inline bool vfsuid_eq(vfsuid_t left, vfsuid_t right)
61 return vfsuid_valid(left) && __vfsuid_val(left) == __vfsuid_val(right);
64 static inline bool vfsgid_eq(vfsgid_t left, vfsgid_t right)
66 return vfsgid_valid(left) && __vfsgid_val(left) == __vfsgid_val(right);
70 * vfsuid_eq_kuid - check whether kuid and vfsuid have the same value
71 * @vfsuid: the vfsuid to compare
72 * @kuid: the kuid to compare
74 * Check whether @vfsuid and @kuid have the same values.
76 * Return: true if @vfsuid and @kuid have the same value, false if not.
77 * Comparison between two invalid uids returns false.
79 static inline bool vfsuid_eq_kuid(vfsuid_t vfsuid, kuid_t kuid)
81 return vfsuid_valid(vfsuid) && __vfsuid_val(vfsuid) == __kuid_val(kuid);
85 * vfsgid_eq_kgid - check whether kgid and vfsgid have the same value
86 * @vfsgid: the vfsgid to compare
87 * @kgid: the kgid to compare
89 * Check whether @vfsgid and @kgid have the same values.
91 * Return: true if @vfsgid and @kgid have the same value, false if not.
92 * Comparison between two invalid gids returns false.
94 static inline bool vfsgid_eq_kgid(vfsgid_t vfsgid, kgid_t kgid)
96 return vfsgid_valid(vfsgid) && __vfsgid_val(vfsgid) == __kgid_val(kgid);
100 * vfs{g,u}ids are created from k{g,u}ids.
101 * We don't allow them to be created from regular {u,g}id.
103 #define VFSUIDT_INIT(val) (vfsuid_t){ __kuid_val(val) }
104 #define VFSGIDT_INIT(val) (vfsgid_t){ __kgid_val(val) }
106 #define INVALID_VFSUID VFSUIDT_INIT(INVALID_UID)
107 #define INVALID_VFSGID VFSGIDT_INIT(INVALID_GID)
110 * Allow a vfs{g,u}id to be used as a k{g,u}id where we want to compare
111 * whether the mapped value is identical to value of a k{g,u}id.
113 #define AS_KUIDT(val) (kuid_t){ __vfsuid_val(val) }
114 #define AS_KGIDT(val) (kgid_t){ __vfsgid_val(val) }
116 #ifdef CONFIG_MULTIUSER
118 * vfsgid_in_group_p() - check whether a vfsuid matches the caller's groups
119 * @vfsgid: the mnt gid to match
121 * This function can be used to determine whether @vfsuid matches any of the
124 * Return: 1 if vfsuid matches caller's groups, 0 if not.
126 static inline int vfsgid_in_group_p(vfsgid_t vfsgid)
128 return in_group_p(AS_KGIDT(vfsgid));
131 static inline int vfsgid_in_group_p(vfsgid_t vfsgid)
138 * initial_idmapping - check whether this is the initial mapping
139 * @ns: idmapping to check
141 * Check whether this is the initial mapping, mapping 0 to 0, 1 to 1,
142 * [...], 1000 to 1000 [...].
144 * Return: true if this is the initial mapping, false if not.
146 static inline bool initial_idmapping(const struct user_namespace *ns)
148 return ns == &init_user_ns;
152 * no_idmapping - check whether we can skip remapping a kuid/gid
153 * @mnt_userns: the mount's idmapping
154 * @fs_userns: the filesystem's idmapping
156 * This function can be used to check whether a remapping between two
157 * idmappings is required.
158 * An idmapped mount is a mount that has an idmapping attached to it that
159 * is different from the filsystem's idmapping and the initial idmapping.
160 * If the initial mapping is used or the idmapping of the mount and the
161 * filesystem are identical no remapping is required.
163 * Return: true if remapping can be skipped, false if not.
165 static inline bool no_idmapping(const struct user_namespace *mnt_userns,
166 const struct user_namespace *fs_userns)
168 return initial_idmapping(mnt_userns) || mnt_userns == fs_userns;
172 * make_vfsuid - map a filesystem kuid into a mnt_userns
173 * @idmap: the mount's idmapping
174 * @fs_userns: the filesystem's idmapping
175 * @kuid : kuid to be mapped
177 * Take a @kuid and remap it from @fs_userns into @mnt_userns. Use this
178 * function when preparing a @kuid to be reported to userspace.
180 * If no_idmapping() determines that this is not an idmapped mount we can
181 * simply return @kuid unchanged.
182 * If initial_idmapping() tells us that the filesystem is not mounted with an
183 * idmapping we know the value of @kuid won't change when calling
184 * from_kuid() so we can simply retrieve the value via __kuid_val()
187 * Return: @kuid mapped according to @mnt_userns.
188 * If @kuid has no mapping in either @mnt_userns or @fs_userns INVALID_UID is
192 static inline vfsuid_t make_vfsuid(struct mnt_idmap *idmap,
193 struct user_namespace *fs_userns,
197 struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
199 if (no_idmapping(mnt_userns, fs_userns))
200 return VFSUIDT_INIT(kuid);
201 if (initial_idmapping(fs_userns))
202 uid = __kuid_val(kuid);
204 uid = from_kuid(fs_userns, kuid);
205 if (uid == (uid_t)-1)
206 return INVALID_VFSUID;
207 return VFSUIDT_INIT(make_kuid(mnt_userns, uid));
211 * make_vfsgid - map a filesystem kgid into a mnt_userns
212 * @idmap: the mount's idmapping
213 * @fs_userns: the filesystem's idmapping
214 * @kgid : kgid to be mapped
216 * Take a @kgid and remap it from @fs_userns into @mnt_userns. Use this
217 * function when preparing a @kgid to be reported to userspace.
219 * If no_idmapping() determines that this is not an idmapped mount we can
220 * simply return @kgid unchanged.
221 * If initial_idmapping() tells us that the filesystem is not mounted with an
222 * idmapping we know the value of @kgid won't change when calling
223 * from_kgid() so we can simply retrieve the value via __kgid_val()
226 * Return: @kgid mapped according to @mnt_userns.
227 * If @kgid has no mapping in either @mnt_userns or @fs_userns INVALID_GID is
231 static inline vfsgid_t make_vfsgid(struct mnt_idmap *idmap,
232 struct user_namespace *fs_userns,
236 struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
238 if (no_idmapping(mnt_userns, fs_userns))
239 return VFSGIDT_INIT(kgid);
240 if (initial_idmapping(fs_userns))
241 gid = __kgid_val(kgid);
243 gid = from_kgid(fs_userns, kgid);
244 if (gid == (gid_t)-1)
245 return INVALID_VFSGID;
246 return VFSGIDT_INIT(make_kgid(mnt_userns, gid));
250 * from_vfsuid - map a vfsuid into the filesystem idmapping
251 * @idmap: the mount's idmapping
252 * @fs_userns: the filesystem's idmapping
253 * @vfsuid : vfsuid to be mapped
255 * Map @vfsuid into the filesystem idmapping. This function has to be used in
256 * order to e.g. write @vfsuid to inode->i_uid.
258 * Return: @vfsuid mapped into the filesystem idmapping
260 static inline kuid_t from_vfsuid(struct mnt_idmap *idmap,
261 struct user_namespace *fs_userns,
265 struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
267 if (no_idmapping(mnt_userns, fs_userns))
268 return AS_KUIDT(vfsuid);
269 uid = from_kuid(mnt_userns, AS_KUIDT(vfsuid));
270 if (uid == (uid_t)-1)
272 if (initial_idmapping(fs_userns))
273 return KUIDT_INIT(uid);
274 return make_kuid(fs_userns, uid);
278 * vfsuid_has_fsmapping - check whether a vfsuid maps into the filesystem
279 * @idmap: the mount's idmapping
280 * @fs_userns: the filesystem's idmapping
281 * @vfsuid: vfsuid to be mapped
283 * Check whether @vfsuid has a mapping in the filesystem idmapping. Use this
284 * function to check whether the filesystem idmapping has a mapping for
287 * Return: true if @vfsuid has a mapping in the filesystem, false if not.
289 static inline bool vfsuid_has_fsmapping(struct mnt_idmap *idmap,
290 struct user_namespace *fs_userns,
293 return uid_valid(from_vfsuid(idmap, fs_userns, vfsuid));
296 static inline bool vfsuid_has_mapping(struct user_namespace *userns,
299 return from_kuid(userns, AS_KUIDT(vfsuid)) != (uid_t)-1;
303 * vfsuid_into_kuid - convert vfsuid into kuid
304 * @vfsuid: the vfsuid to convert
306 * This can be used when a vfsuid is committed as a kuid.
308 * Return: a kuid with the value of @vfsuid
310 static inline kuid_t vfsuid_into_kuid(vfsuid_t vfsuid)
312 return AS_KUIDT(vfsuid);
316 * from_vfsgid - map a vfsgid into the filesystem idmapping
317 * @idmap: the mount's idmapping
318 * @fs_userns: the filesystem's idmapping
319 * @vfsgid : vfsgid to be mapped
321 * Map @vfsgid into the filesystem idmapping. This function has to be used in
322 * order to e.g. write @vfsgid to inode->i_gid.
324 * Return: @vfsgid mapped into the filesystem idmapping
326 static inline kgid_t from_vfsgid(struct mnt_idmap *idmap,
327 struct user_namespace *fs_userns,
331 struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
333 if (no_idmapping(mnt_userns, fs_userns))
334 return AS_KGIDT(vfsgid);
335 gid = from_kgid(mnt_userns, AS_KGIDT(vfsgid));
336 if (gid == (gid_t)-1)
338 if (initial_idmapping(fs_userns))
339 return KGIDT_INIT(gid);
340 return make_kgid(fs_userns, gid);
344 * vfsgid_has_fsmapping - check whether a vfsgid maps into the filesystem
345 * @idmap: the mount's idmapping
346 * @fs_userns: the filesystem's idmapping
347 * @vfsgid: vfsgid to be mapped
349 * Check whether @vfsgid has a mapping in the filesystem idmapping. Use this
350 * function to check whether the filesystem idmapping has a mapping for
353 * Return: true if @vfsgid has a mapping in the filesystem, false if not.
355 static inline bool vfsgid_has_fsmapping(struct mnt_idmap *idmap,
356 struct user_namespace *fs_userns,
359 return gid_valid(from_vfsgid(idmap, fs_userns, vfsgid));
362 static inline bool vfsgid_has_mapping(struct user_namespace *userns,
365 return from_kgid(userns, AS_KGIDT(vfsgid)) != (gid_t)-1;
369 * vfsgid_into_kgid - convert vfsgid into kgid
370 * @vfsgid: the vfsgid to convert
372 * This can be used when a vfsgid is committed as a kgid.
374 * Return: a kgid with the value of @vfsgid
376 static inline kgid_t vfsgid_into_kgid(vfsgid_t vfsgid)
378 return AS_KGIDT(vfsgid);
382 * mapped_fsuid - return caller's fsuid mapped according to an idmapping
383 * @idmap: the mount's idmapping
384 * @fs_userns: the filesystem's idmapping
386 * Use this helper to initialize a new vfs or filesystem object based on
387 * the caller's fsuid. A common example is initializing the i_uid field of
388 * a newly allocated inode triggered by a creation event such as mkdir or
389 * O_CREAT. Other examples include the allocation of quotas for a specific
392 * Return: the caller's current fsuid mapped up according to @idmap.
394 static inline kuid_t mapped_fsuid(struct mnt_idmap *idmap,
395 struct user_namespace *fs_userns)
397 return from_vfsuid(idmap, fs_userns, VFSUIDT_INIT(current_fsuid()));
401 * mapped_fsgid - return caller's fsgid mapped according to an idmapping
402 * @idmap: the mount's idmapping
403 * @fs_userns: the filesystem's idmapping
405 * Use this helper to initialize a new vfs or filesystem object based on
406 * the caller's fsgid. A common example is initializing the i_gid field of
407 * a newly allocated inode triggered by a creation event such as mkdir or
408 * O_CREAT. Other examples include the allocation of quotas for a specific
411 * Return: the caller's current fsgid mapped up according to @idmap.
413 static inline kgid_t mapped_fsgid(struct mnt_idmap *idmap,
414 struct user_namespace *fs_userns)
416 return from_vfsgid(idmap, fs_userns, VFSGIDT_INIT(current_fsgid()));
419 #endif /* _LINUX_MNT_IDMAPPING_H */