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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
8struct mnt_idmap;
9struct user_namespace;
10
11extern struct mnt_idmap nop_mnt_idmap;
12extern struct user_namespace init_user_ns;
13
14typedef struct {
15 uid_t val;
16} vfsuid_t;
17
18typedef struct {
19 gid_t val;
20} vfsgid_t;
21
22static_assert(sizeof(vfsuid_t) == sizeof(kuid_t));
23static_assert(sizeof(vfsgid_t) == sizeof(kgid_t));
24static_assert(offsetof(vfsuid_t, val) == offsetof(kuid_t, val));
25static_assert(offsetof(vfsgid_t, val) == offsetof(kgid_t, val));
26
27#ifdef CONFIG_MULTIUSER
28static inline uid_t __vfsuid_val(vfsuid_t uid)
29{
30 return uid.val;
31}
32
33static inline gid_t __vfsgid_val(vfsgid_t gid)
34{
35 return gid.val;
36}
37#else
38static inline uid_t __vfsuid_val(vfsuid_t uid)
39{
40 return 0;
41}
42
43static inline gid_t __vfsgid_val(vfsgid_t gid)
44{
45 return 0;
46}
47#endif
48
49static inline bool vfsuid_valid(vfsuid_t uid)
50{
51 return __vfsuid_val(uid) != (uid_t)-1;
52}
53
54static inline bool vfsgid_valid(vfsgid_t gid)
55{
56 return __vfsgid_val(gid) != (gid_t)-1;
57}
58
59static inline bool vfsuid_eq(vfsuid_t left, vfsuid_t right)
60{
61 return vfsuid_valid(left) && __vfsuid_val(left) == __vfsuid_val(right);
62}
63
64static inline bool vfsgid_eq(vfsgid_t left, vfsgid_t right)
65{
66 return vfsgid_valid(left) && __vfsgid_val(left) == __vfsgid_val(right);
67}
68
69/**
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
73 *
74 * Check whether @vfsuid and @kuid have the same values.
75 *
76 * Return: true if @vfsuid and @kuid have the same value, false if not.
77 * Comparison between two invalid uids returns false.
78 */
79static inline bool vfsuid_eq_kuid(vfsuid_t vfsuid, kuid_t kuid)
80{
81 return vfsuid_valid(vfsuid) && __vfsuid_val(vfsuid) == __kuid_val(kuid);
82}
83
84/**
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
88 *
89 * Check whether @vfsgid and @kgid have the same values.
90 *
91 * Return: true if @vfsgid and @kgid have the same value, false if not.
92 * Comparison between two invalid gids returns false.
93 */
94static inline bool vfsgid_eq_kgid(vfsgid_t vfsgid, kgid_t kgid)
95{
96 return vfsgid_valid(vfsgid) && __vfsgid_val(vfsgid) == __kgid_val(kgid);
97}
98
99/*
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.
102 */
103#define VFSUIDT_INIT(val) (vfsuid_t){ __kuid_val(val) }
104#define VFSGIDT_INIT(val) (vfsgid_t){ __kgid_val(val) }
105
106#define INVALID_VFSUID VFSUIDT_INIT(INVALID_UID)
107#define INVALID_VFSGID VFSGIDT_INIT(INVALID_GID)
108
109/*
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.
112 */
113#define AS_KUIDT(val) (kuid_t){ __vfsuid_val(val) }
114#define AS_KGIDT(val) (kgid_t){ __vfsgid_val(val) }
115
116int vfsgid_in_group_p(vfsgid_t vfsgid);
117
118vfsuid_t make_vfsuid(struct mnt_idmap *idmap,
119 struct user_namespace *fs_userns, kuid_t kuid);
120
121vfsgid_t make_vfsgid(struct mnt_idmap *idmap,
122 struct user_namespace *fs_userns, kgid_t kgid);
123
124kuid_t from_vfsuid(struct mnt_idmap *idmap,
125 struct user_namespace *fs_userns, vfsuid_t vfsuid);
126
127kgid_t from_vfsgid(struct mnt_idmap *idmap,
128 struct user_namespace *fs_userns, vfsgid_t vfsgid);
129
130/**
131 * vfsuid_has_fsmapping - check whether a vfsuid maps into the filesystem
132 * @idmap: the mount's idmapping
133 * @fs_userns: the filesystem's idmapping
134 * @vfsuid: vfsuid to be mapped
135 *
136 * Check whether @vfsuid has a mapping in the filesystem idmapping. Use this
137 * function to check whether the filesystem idmapping has a mapping for
138 * @vfsuid.
139 *
140 * Return: true if @vfsuid has a mapping in the filesystem, false if not.
141 */
142static inline bool vfsuid_has_fsmapping(struct mnt_idmap *idmap,
143 struct user_namespace *fs_userns,
144 vfsuid_t vfsuid)
145{
146 return uid_valid(from_vfsuid(idmap, fs_userns, vfsuid));
147}
148
149static inline bool vfsuid_has_mapping(struct user_namespace *userns,
150 vfsuid_t vfsuid)
151{
152 return from_kuid(userns, AS_KUIDT(vfsuid)) != (uid_t)-1;
153}
154
155/**
156 * vfsuid_into_kuid - convert vfsuid into kuid
157 * @vfsuid: the vfsuid to convert
158 *
159 * This can be used when a vfsuid is committed as a kuid.
160 *
161 * Return: a kuid with the value of @vfsuid
162 */
163static inline kuid_t vfsuid_into_kuid(vfsuid_t vfsuid)
164{
165 return AS_KUIDT(vfsuid);
166}
167
168/**
169 * vfsgid_has_fsmapping - check whether a vfsgid maps into the filesystem
170 * @idmap: the mount's idmapping
171 * @fs_userns: the filesystem's idmapping
172 * @vfsgid: vfsgid to be mapped
173 *
174 * Check whether @vfsgid has a mapping in the filesystem idmapping. Use this
175 * function to check whether the filesystem idmapping has a mapping for
176 * @vfsgid.
177 *
178 * Return: true if @vfsgid has a mapping in the filesystem, false if not.
179 */
180static inline bool vfsgid_has_fsmapping(struct mnt_idmap *idmap,
181 struct user_namespace *fs_userns,
182 vfsgid_t vfsgid)
183{
184 return gid_valid(from_vfsgid(idmap, fs_userns, vfsgid));
185}
186
187static inline bool vfsgid_has_mapping(struct user_namespace *userns,
188 vfsgid_t vfsgid)
189{
190 return from_kgid(userns, AS_KGIDT(vfsgid)) != (gid_t)-1;
191}
192
193/**
194 * vfsgid_into_kgid - convert vfsgid into kgid
195 * @vfsgid: the vfsgid to convert
196 *
197 * This can be used when a vfsgid is committed as a kgid.
198 *
199 * Return: a kgid with the value of @vfsgid
200 */
201static inline kgid_t vfsgid_into_kgid(vfsgid_t vfsgid)
202{
203 return AS_KGIDT(vfsgid);
204}
205
206/**
207 * mapped_fsuid - return caller's fsuid mapped according to an idmapping
208 * @idmap: the mount's idmapping
209 * @fs_userns: the filesystem's idmapping
210 *
211 * Use this helper to initialize a new vfs or filesystem object based on
212 * the caller's fsuid. A common example is initializing the i_uid field of
213 * a newly allocated inode triggered by a creation event such as mkdir or
214 * O_CREAT. Other examples include the allocation of quotas for a specific
215 * user.
216 *
217 * Return: the caller's current fsuid mapped up according to @idmap.
218 */
219static inline kuid_t mapped_fsuid(struct mnt_idmap *idmap,
220 struct user_namespace *fs_userns)
221{
222 return from_vfsuid(idmap, fs_userns, VFSUIDT_INIT(current_fsuid()));
223}
224
225/**
226 * mapped_fsgid - return caller's fsgid mapped according to an idmapping
227 * @idmap: the mount's idmapping
228 * @fs_userns: the filesystem's idmapping
229 *
230 * Use this helper to initialize a new vfs or filesystem object based on
231 * the caller's fsgid. A common example is initializing the i_gid field of
232 * a newly allocated inode triggered by a creation event such as mkdir or
233 * O_CREAT. Other examples include the allocation of quotas for a specific
234 * user.
235 *
236 * Return: the caller's current fsgid mapped up according to @idmap.
237 */
238static inline kgid_t mapped_fsgid(struct mnt_idmap *idmap,
239 struct user_namespace *fs_userns)
240{
241 return from_vfsgid(idmap, fs_userns, VFSGIDT_INIT(current_fsgid()));
242}
243
244bool check_fsmapping(const struct mnt_idmap *idmap,
245 const struct super_block *sb);
246
247#endif /* _LINUX_MNT_IDMAPPING_H */