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1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef _LINUX_MNT_IDMAPPING_H | |
3 | #define _LINUX_MNT_IDMAPPING_H | |
4 | ||
5 | #include <linux/types.h> | |
6 | #include <linux/uidgid.h> | |
7 | ||
8 | struct user_namespace; | |
1ac2a410 CB |
9 | /* |
10 | * Carries the initial idmapping of 0:0:4294967295 which is an identity | |
11 | * mapping. This means that {g,u}id 0 is mapped to {g,u}id 0, {g,u}id 1 is | |
12 | * mapped to {g,u}id 1, [...], {g,u}id 1000 to {g,u}id 1000, [...]. | |
13 | */ | |
a793d79e CB |
14 | extern struct user_namespace init_user_ns; |
15 | ||
1e5267cd CB |
16 | typedef struct { |
17 | uid_t val; | |
18 | } vfsuid_t; | |
19 | ||
20 | typedef struct { | |
21 | gid_t val; | |
22 | } vfsgid_t; | |
23 | ||
45c31150 CB |
24 | static_assert(sizeof(vfsuid_t) == sizeof(kuid_t)); |
25 | static_assert(sizeof(vfsgid_t) == sizeof(kgid_t)); | |
26 | static_assert(offsetof(vfsuid_t, val) == offsetof(kuid_t, val)); | |
27 | static_assert(offsetof(vfsgid_t, val) == offsetof(kgid_t, val)); | |
28 | ||
1e5267cd CB |
29 | #ifdef CONFIG_MULTIUSER |
30 | static inline uid_t __vfsuid_val(vfsuid_t uid) | |
31 | { | |
32 | return uid.val; | |
33 | } | |
34 | ||
35 | static inline gid_t __vfsgid_val(vfsgid_t gid) | |
36 | { | |
37 | return gid.val; | |
38 | } | |
39 | #else | |
40 | static inline uid_t __vfsuid_val(vfsuid_t uid) | |
41 | { | |
42 | return 0; | |
43 | } | |
44 | ||
45 | static inline gid_t __vfsgid_val(vfsgid_t gid) | |
46 | { | |
47 | return 0; | |
48 | } | |
49 | #endif | |
50 | ||
51 | static inline bool vfsuid_valid(vfsuid_t uid) | |
52 | { | |
53 | return __vfsuid_val(uid) != (uid_t)-1; | |
54 | } | |
55 | ||
56 | static inline bool vfsgid_valid(vfsgid_t gid) | |
57 | { | |
58 | return __vfsgid_val(gid) != (gid_t)-1; | |
59 | } | |
60 | ||
61 | static inline bool vfsuid_eq(vfsuid_t left, vfsuid_t right) | |
62 | { | |
4d0548a7 | 63 | return vfsuid_valid(left) && __vfsuid_val(left) == __vfsuid_val(right); |
1e5267cd CB |
64 | } |
65 | ||
66 | static inline bool vfsgid_eq(vfsgid_t left, vfsgid_t right) | |
67 | { | |
4d0548a7 | 68 | return vfsgid_valid(left) && __vfsgid_val(left) == __vfsgid_val(right); |
1e5267cd CB |
69 | } |
70 | ||
71 | /** | |
72 | * vfsuid_eq_kuid - check whether kuid and vfsuid have the same value | |
73 | * @kuid: the kuid to compare | |
74 | * @vfsuid: the vfsuid to compare | |
75 | * | |
76 | * Check whether @kuid and @vfsuid have the same values. | |
77 | * | |
78 | * Return: true if @kuid and @vfsuid have the same value, false if not. | |
4d0548a7 | 79 | * Comparison between two invalid uids returns false. |
1e5267cd CB |
80 | */ |
81 | static inline bool vfsuid_eq_kuid(vfsuid_t vfsuid, kuid_t kuid) | |
82 | { | |
4d0548a7 | 83 | return vfsuid_valid(vfsuid) && __vfsuid_val(vfsuid) == __kuid_val(kuid); |
1e5267cd CB |
84 | } |
85 | ||
86 | /** | |
87 | * vfsgid_eq_kgid - check whether kgid and vfsgid have the same value | |
88 | * @kgid: the kgid to compare | |
89 | * @vfsgid: the vfsgid to compare | |
90 | * | |
91 | * Check whether @kgid and @vfsgid have the same values. | |
92 | * | |
93 | * Return: true if @kgid and @vfsgid have the same value, false if not. | |
4d0548a7 | 94 | * Comparison between two invalid gids returns false. |
1e5267cd CB |
95 | */ |
96 | static inline bool vfsgid_eq_kgid(kgid_t kgid, vfsgid_t vfsgid) | |
97 | { | |
4d0548a7 | 98 | return vfsgid_valid(vfsgid) && __vfsgid_val(vfsgid) == __kgid_val(kgid); |
1e5267cd CB |
99 | } |
100 | ||
101 | /* | |
102 | * vfs{g,u}ids are created from k{g,u}ids. | |
103 | * We don't allow them to be created from regular {u,g}id. | |
104 | */ | |
105 | #define VFSUIDT_INIT(val) (vfsuid_t){ __kuid_val(val) } | |
106 | #define VFSGIDT_INIT(val) (vfsgid_t){ __kgid_val(val) } | |
107 | ||
108 | #define INVALID_VFSUID VFSUIDT_INIT(INVALID_UID) | |
109 | #define INVALID_VFSGID VFSGIDT_INIT(INVALID_GID) | |
110 | ||
111 | /* | |
112 | * Allow a vfs{g,u}id to be used as a k{g,u}id where we want to compare | |
113 | * whether the mapped value is identical to value of a k{g,u}id. | |
114 | */ | |
115 | #define AS_KUIDT(val) (kuid_t){ __vfsuid_val(val) } | |
116 | #define AS_KGIDT(val) (kgid_t){ __vfsgid_val(val) } | |
117 | ||
118 | #ifdef CONFIG_MULTIUSER | |
119 | /** | |
120 | * vfsgid_in_group_p() - check whether a vfsuid matches the caller's groups | |
121 | * @vfsgid: the mnt gid to match | |
122 | * | |
123 | * This function can be used to determine whether @vfsuid matches any of the | |
124 | * caller's groups. | |
125 | * | |
126 | * Return: 1 if vfsuid matches caller's groups, 0 if not. | |
127 | */ | |
128 | static inline int vfsgid_in_group_p(vfsgid_t vfsgid) | |
129 | { | |
130 | return in_group_p(AS_KGIDT(vfsgid)); | |
131 | } | |
132 | #else | |
133 | static inline int vfsgid_in_group_p(vfsgid_t vfsgid) | |
134 | { | |
135 | return 1; | |
136 | } | |
137 | #endif | |
138 | ||
1ac2a410 CB |
139 | /** |
140 | * initial_idmapping - check whether this is the initial mapping | |
141 | * @ns: idmapping to check | |
142 | * | |
143 | * Check whether this is the initial mapping, mapping 0 to 0, 1 to 1, | |
144 | * [...], 1000 to 1000 [...]. | |
145 | * | |
146 | * Return: true if this is the initial mapping, false if not. | |
147 | */ | |
148 | static inline bool initial_idmapping(const struct user_namespace *ns) | |
149 | { | |
150 | return ns == &init_user_ns; | |
151 | } | |
152 | ||
153 | /** | |
154 | * no_idmapping - check whether we can skip remapping a kuid/gid | |
155 | * @mnt_userns: the mount's idmapping | |
156 | * @fs_userns: the filesystem's idmapping | |
157 | * | |
158 | * This function can be used to check whether a remapping between two | |
159 | * idmappings is required. | |
160 | * An idmapped mount is a mount that has an idmapping attached to it that | |
161 | * is different from the filsystem's idmapping and the initial idmapping. | |
162 | * If the initial mapping is used or the idmapping of the mount and the | |
163 | * filesystem are identical no remapping is required. | |
164 | * | |
165 | * Return: true if remapping can be skipped, false if not. | |
166 | */ | |
167 | static inline bool no_idmapping(const struct user_namespace *mnt_userns, | |
168 | const struct user_namespace *fs_userns) | |
169 | { | |
170 | return initial_idmapping(mnt_userns) || mnt_userns == fs_userns; | |
171 | } | |
172 | ||
173 | /** | |
174 | * mapped_kuid_fs - map a filesystem kuid into a mnt_userns | |
175 | * @mnt_userns: the mount's idmapping | |
176 | * @fs_userns: the filesystem's idmapping | |
177 | * @kuid : kuid to be mapped | |
178 | * | |
179 | * Take a @kuid and remap it from @fs_userns into @mnt_userns. Use this | |
180 | * function when preparing a @kuid to be reported to userspace. | |
181 | * | |
182 | * If no_idmapping() determines that this is not an idmapped mount we can | |
183 | * simply return @kuid unchanged. | |
184 | * If initial_idmapping() tells us that the filesystem is not mounted with an | |
185 | * idmapping we know the value of @kuid won't change when calling | |
186 | * from_kuid() so we can simply retrieve the value via __kuid_val() | |
187 | * directly. | |
188 | * | |
189 | * Return: @kuid mapped according to @mnt_userns. | |
190 | * If @kuid has no mapping in either @mnt_userns or @fs_userns INVALID_UID is | |
191 | * returned. | |
192 | */ | |
1e5267cd CB |
193 | |
194 | static inline vfsuid_t make_vfsuid(struct user_namespace *mnt_userns, | |
195 | struct user_namespace *fs_userns, | |
196 | kuid_t kuid) | |
1ac2a410 CB |
197 | { |
198 | uid_t uid; | |
199 | ||
200 | if (no_idmapping(mnt_userns, fs_userns)) | |
1e5267cd | 201 | return VFSUIDT_INIT(kuid); |
1ac2a410 CB |
202 | if (initial_idmapping(fs_userns)) |
203 | uid = __kuid_val(kuid); | |
204 | else | |
205 | uid = from_kuid(fs_userns, kuid); | |
206 | if (uid == (uid_t)-1) | |
1e5267cd CB |
207 | return INVALID_VFSUID; |
208 | return VFSUIDT_INIT(make_kuid(mnt_userns, uid)); | |
209 | } | |
210 | ||
211 | static inline kuid_t mapped_kuid_fs(struct user_namespace *mnt_userns, | |
212 | struct user_namespace *fs_userns, | |
213 | kuid_t kuid) | |
214 | { | |
215 | return AS_KUIDT(make_vfsuid(mnt_userns, fs_userns, kuid)); | |
1ac2a410 CB |
216 | } |
217 | ||
218 | /** | |
219 | * mapped_kgid_fs - map a filesystem kgid into a mnt_userns | |
220 | * @mnt_userns: the mount's idmapping | |
221 | * @fs_userns: the filesystem's idmapping | |
222 | * @kgid : kgid to be mapped | |
223 | * | |
224 | * Take a @kgid and remap it from @fs_userns into @mnt_userns. Use this | |
225 | * function when preparing a @kgid to be reported to userspace. | |
226 | * | |
227 | * If no_idmapping() determines that this is not an idmapped mount we can | |
228 | * simply return @kgid unchanged. | |
229 | * If initial_idmapping() tells us that the filesystem is not mounted with an | |
230 | * idmapping we know the value of @kgid won't change when calling | |
231 | * from_kgid() so we can simply retrieve the value via __kgid_val() | |
232 | * directly. | |
233 | * | |
234 | * Return: @kgid mapped according to @mnt_userns. | |
235 | * If @kgid has no mapping in either @mnt_userns or @fs_userns INVALID_GID is | |
236 | * returned. | |
237 | */ | |
1e5267cd CB |
238 | |
239 | static inline vfsgid_t make_vfsgid(struct user_namespace *mnt_userns, | |
240 | struct user_namespace *fs_userns, | |
241 | kgid_t kgid) | |
1ac2a410 CB |
242 | { |
243 | gid_t gid; | |
244 | ||
245 | if (no_idmapping(mnt_userns, fs_userns)) | |
1e5267cd | 246 | return VFSGIDT_INIT(kgid); |
1ac2a410 CB |
247 | if (initial_idmapping(fs_userns)) |
248 | gid = __kgid_val(kgid); | |
249 | else | |
250 | gid = from_kgid(fs_userns, kgid); | |
251 | if (gid == (gid_t)-1) | |
1e5267cd CB |
252 | return INVALID_VFSGID; |
253 | return VFSGIDT_INIT(make_kgid(mnt_userns, gid)); | |
254 | } | |
255 | ||
256 | static inline kgid_t mapped_kgid_fs(struct user_namespace *mnt_userns, | |
257 | struct user_namespace *fs_userns, | |
258 | kgid_t kgid) | |
259 | { | |
260 | return AS_KGIDT(make_vfsgid(mnt_userns, fs_userns, kgid)); | |
261 | } | |
262 | ||
263 | /** | |
264 | * from_vfsuid - map a vfsuid into the filesystem idmapping | |
265 | * @mnt_userns: the mount's idmapping | |
266 | * @fs_userns: the filesystem's idmapping | |
267 | * @vfsuid : vfsuid to be mapped | |
268 | * | |
269 | * Map @vfsuid into the filesystem idmapping. This function has to be used in | |
270 | * order to e.g. write @vfsuid to inode->i_uid. | |
271 | * | |
272 | * Return: @vfsuid mapped into the filesystem idmapping | |
273 | */ | |
274 | static inline kuid_t from_vfsuid(struct user_namespace *mnt_userns, | |
275 | struct user_namespace *fs_userns, | |
276 | vfsuid_t vfsuid) | |
277 | { | |
278 | uid_t uid; | |
279 | ||
280 | if (no_idmapping(mnt_userns, fs_userns)) | |
281 | return AS_KUIDT(vfsuid); | |
282 | uid = from_kuid(mnt_userns, AS_KUIDT(vfsuid)); | |
283 | if (uid == (uid_t)-1) | |
284 | return INVALID_UID; | |
285 | if (initial_idmapping(fs_userns)) | |
286 | return KUIDT_INIT(uid); | |
287 | return make_kuid(fs_userns, uid); | |
1ac2a410 CB |
288 | } |
289 | ||
290 | /** | |
291 | * mapped_kuid_user - map a user kuid into a mnt_userns | |
292 | * @mnt_userns: the mount's idmapping | |
293 | * @fs_userns: the filesystem's idmapping | |
294 | * @kuid : kuid to be mapped | |
295 | * | |
296 | * Use the idmapping of @mnt_userns to remap a @kuid into @fs_userns. Use this | |
297 | * function when preparing a @kuid to be written to disk or inode. | |
298 | * | |
299 | * If no_idmapping() determines that this is not an idmapped mount we can | |
300 | * simply return @kuid unchanged. | |
301 | * If initial_idmapping() tells us that the filesystem is not mounted with an | |
302 | * idmapping we know the value of @kuid won't change when calling | |
303 | * make_kuid() so we can simply retrieve the value via KUIDT_INIT() | |
304 | * directly. | |
305 | * | |
306 | * Return: @kuid mapped according to @mnt_userns. | |
307 | * If @kuid has no mapping in either @mnt_userns or @fs_userns INVALID_UID is | |
308 | * returned. | |
309 | */ | |
310 | static inline kuid_t mapped_kuid_user(struct user_namespace *mnt_userns, | |
311 | struct user_namespace *fs_userns, | |
312 | kuid_t kuid) | |
313 | { | |
1e5267cd CB |
314 | return from_vfsuid(mnt_userns, fs_userns, VFSUIDT_INIT(kuid)); |
315 | } | |
316 | ||
317 | /** | |
318 | * vfsuid_has_fsmapping - check whether a vfsuid maps into the filesystem | |
319 | * @mnt_userns: the mount's idmapping | |
320 | * @fs_userns: the filesystem's idmapping | |
321 | * @vfsuid: vfsuid to be mapped | |
322 | * | |
323 | * Check whether @vfsuid has a mapping in the filesystem idmapping. Use this | |
324 | * function to check whether the filesystem idmapping has a mapping for | |
325 | * @vfsuid. | |
326 | * | |
327 | * Return: true if @vfsuid has a mapping in the filesystem, false if not. | |
328 | */ | |
329 | static inline bool vfsuid_has_fsmapping(struct user_namespace *mnt_userns, | |
330 | struct user_namespace *fs_userns, | |
331 | vfsuid_t vfsuid) | |
332 | { | |
333 | return uid_valid(from_vfsuid(mnt_userns, fs_userns, vfsuid)); | |
334 | } | |
335 | ||
336 | /** | |
337 | * from_vfsgid - map a vfsgid into the filesystem idmapping | |
338 | * @mnt_userns: the mount's idmapping | |
339 | * @fs_userns: the filesystem's idmapping | |
340 | * @vfsgid : vfsgid to be mapped | |
341 | * | |
342 | * Map @vfsgid into the filesystem idmapping. This function has to be used in | |
343 | * order to e.g. write @vfsgid to inode->i_gid. | |
344 | * | |
345 | * Return: @vfsgid mapped into the filesystem idmapping | |
346 | */ | |
347 | static inline kgid_t from_vfsgid(struct user_namespace *mnt_userns, | |
348 | struct user_namespace *fs_userns, | |
349 | vfsgid_t vfsgid) | |
350 | { | |
351 | gid_t gid; | |
1ac2a410 CB |
352 | |
353 | if (no_idmapping(mnt_userns, fs_userns)) | |
1e5267cd CB |
354 | return AS_KGIDT(vfsgid); |
355 | gid = from_kgid(mnt_userns, AS_KGIDT(vfsgid)); | |
356 | if (gid == (gid_t)-1) | |
357 | return INVALID_GID; | |
1ac2a410 | 358 | if (initial_idmapping(fs_userns)) |
1e5267cd CB |
359 | return KGIDT_INIT(gid); |
360 | return make_kgid(fs_userns, gid); | |
1ac2a410 CB |
361 | } |
362 | ||
363 | /** | |
364 | * mapped_kgid_user - map a user kgid into a mnt_userns | |
365 | * @mnt_userns: the mount's idmapping | |
366 | * @fs_userns: the filesystem's idmapping | |
367 | * @kgid : kgid to be mapped | |
368 | * | |
369 | * Use the idmapping of @mnt_userns to remap a @kgid into @fs_userns. Use this | |
370 | * function when preparing a @kgid to be written to disk or inode. | |
371 | * | |
372 | * If no_idmapping() determines that this is not an idmapped mount we can | |
373 | * simply return @kgid unchanged. | |
374 | * If initial_idmapping() tells us that the filesystem is not mounted with an | |
375 | * idmapping we know the value of @kgid won't change when calling | |
376 | * make_kgid() so we can simply retrieve the value via KGIDT_INIT() | |
377 | * directly. | |
378 | * | |
379 | * Return: @kgid mapped according to @mnt_userns. | |
380 | * If @kgid has no mapping in either @mnt_userns or @fs_userns INVALID_GID is | |
381 | * returned. | |
382 | */ | |
383 | static inline kgid_t mapped_kgid_user(struct user_namespace *mnt_userns, | |
384 | struct user_namespace *fs_userns, | |
385 | kgid_t kgid) | |
386 | { | |
1e5267cd CB |
387 | return from_vfsgid(mnt_userns, fs_userns, VFSGIDT_INIT(kgid)); |
388 | } | |
1ac2a410 | 389 | |
1e5267cd CB |
390 | /** |
391 | * vfsgid_has_fsmapping - check whether a vfsgid maps into the filesystem | |
392 | * @mnt_userns: the mount's idmapping | |
393 | * @fs_userns: the filesystem's idmapping | |
394 | * @vfsgid: vfsgid to be mapped | |
395 | * | |
396 | * Check whether @vfsgid has a mapping in the filesystem idmapping. Use this | |
397 | * function to check whether the filesystem idmapping has a mapping for | |
398 | * @vfsgid. | |
399 | * | |
400 | * Return: true if @vfsgid has a mapping in the filesystem, false if not. | |
401 | */ | |
402 | static inline bool vfsgid_has_fsmapping(struct user_namespace *mnt_userns, | |
403 | struct user_namespace *fs_userns, | |
404 | vfsgid_t vfsgid) | |
405 | { | |
406 | return gid_valid(from_vfsgid(mnt_userns, fs_userns, vfsgid)); | |
1ac2a410 CB |
407 | } |
408 | ||
a793d79e CB |
409 | /** |
410 | * mapped_fsuid - return caller's fsuid mapped up into a mnt_userns | |
1ac2a410 | 411 | * @mnt_userns: the mount's idmapping |
209188ce | 412 | * @fs_userns: the filesystem's idmapping |
a793d79e CB |
413 | * |
414 | * Use this helper to initialize a new vfs or filesystem object based on | |
415 | * the caller's fsuid. A common example is initializing the i_uid field of | |
416 | * a newly allocated inode triggered by a creation event such as mkdir or | |
417 | * O_CREAT. Other examples include the allocation of quotas for a specific | |
418 | * user. | |
419 | * | |
420 | * Return: the caller's current fsuid mapped up according to @mnt_userns. | |
421 | */ | |
209188ce CB |
422 | static inline kuid_t mapped_fsuid(struct user_namespace *mnt_userns, |
423 | struct user_namespace *fs_userns) | |
a793d79e | 424 | { |
fc04dafd CB |
425 | return from_vfsuid(mnt_userns, fs_userns, |
426 | VFSUIDT_INIT(current_fsuid())); | |
a793d79e CB |
427 | } |
428 | ||
429 | /** | |
430 | * mapped_fsgid - return caller's fsgid mapped up into a mnt_userns | |
1ac2a410 | 431 | * @mnt_userns: the mount's idmapping |
209188ce | 432 | * @fs_userns: the filesystem's idmapping |
a793d79e CB |
433 | * |
434 | * Use this helper to initialize a new vfs or filesystem object based on | |
435 | * the caller's fsgid. A common example is initializing the i_gid field of | |
436 | * a newly allocated inode triggered by a creation event such as mkdir or | |
437 | * O_CREAT. Other examples include the allocation of quotas for a specific | |
438 | * user. | |
439 | * | |
440 | * Return: the caller's current fsgid mapped up according to @mnt_userns. | |
441 | */ | |
209188ce CB |
442 | static inline kgid_t mapped_fsgid(struct user_namespace *mnt_userns, |
443 | struct user_namespace *fs_userns) | |
a793d79e | 444 | { |
fc04dafd CB |
445 | return from_vfsgid(mnt_userns, fs_userns, |
446 | VFSGIDT_INIT(current_fsgid())); | |
a793d79e CB |
447 | } |
448 | ||
449 | #endif /* _LINUX_MNT_IDMAPPING_H */ |