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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 mnt_idmap invalid_mnt_idmap;
13extern struct user_namespace init_user_ns;
14
15typedef struct {
16 uid_t val;
17} vfsuid_t;
18
19typedef struct {
20 gid_t val;
21} vfsgid_t;
22
23static_assert(sizeof(vfsuid_t) == sizeof(kuid_t));
24static_assert(sizeof(vfsgid_t) == sizeof(kgid_t));
25static_assert(offsetof(vfsuid_t, val) == offsetof(kuid_t, val));
26static_assert(offsetof(vfsgid_t, val) == offsetof(kgid_t, val));
27
28static inline bool is_valid_mnt_idmap(const struct mnt_idmap *idmap)
29{
30 return idmap != &nop_mnt_idmap && idmap != &invalid_mnt_idmap;
31}
32
33#ifdef CONFIG_MULTIUSER
34static inline uid_t __vfsuid_val(vfsuid_t uid)
35{
36 return uid.val;
37}
38
39static inline gid_t __vfsgid_val(vfsgid_t gid)
40{
41 return gid.val;
42}
43#else
44static inline uid_t __vfsuid_val(vfsuid_t uid)
45{
46 return 0;
47}
48
49static inline gid_t __vfsgid_val(vfsgid_t gid)
50{
51 return 0;
52}
53#endif
54
55static inline bool vfsuid_valid(vfsuid_t uid)
56{
57 return __vfsuid_val(uid) != (uid_t)-1;
58}
59
60static inline bool vfsgid_valid(vfsgid_t gid)
61{
62 return __vfsgid_val(gid) != (gid_t)-1;
63}
64
65static inline bool vfsuid_eq(vfsuid_t left, vfsuid_t right)
66{
67 return vfsuid_valid(uid: left) && __vfsuid_val(uid: left) == __vfsuid_val(uid: right);
68}
69
70static inline bool vfsgid_eq(vfsgid_t left, vfsgid_t right)
71{
72 return vfsgid_valid(gid: left) && __vfsgid_val(gid: left) == __vfsgid_val(gid: right);
73}
74
75/**
76 * vfsuid_eq_kuid - check whether kuid and vfsuid have the same value
77 * @vfsuid: the vfsuid to compare
78 * @kuid: the kuid to compare
79 *
80 * Check whether @vfsuid and @kuid have the same values.
81 *
82 * Return: true if @vfsuid and @kuid have the same value, false if not.
83 * Comparison between two invalid uids returns false.
84 */
85static inline bool vfsuid_eq_kuid(vfsuid_t vfsuid, kuid_t kuid)
86{
87 return vfsuid_valid(uid: vfsuid) && __vfsuid_val(uid: vfsuid) == __kuid_val(uid: kuid);
88}
89
90/**
91 * vfsgid_eq_kgid - check whether kgid and vfsgid have the same value
92 * @vfsgid: the vfsgid to compare
93 * @kgid: the kgid to compare
94 *
95 * Check whether @vfsgid and @kgid have the same values.
96 *
97 * Return: true if @vfsgid and @kgid have the same value, false if not.
98 * Comparison between two invalid gids returns false.
99 */
100static inline bool vfsgid_eq_kgid(vfsgid_t vfsgid, kgid_t kgid)
101{
102 return vfsgid_valid(gid: vfsgid) && __vfsgid_val(gid: vfsgid) == __kgid_val(gid: kgid);
103}
104
105/*
106 * vfs{g,u}ids are created from k{g,u}ids.
107 * We don't allow them to be created from regular {u,g}id.
108 */
109#define VFSUIDT_INIT(val) (vfsuid_t){ __kuid_val(val) }
110#define VFSGIDT_INIT(val) (vfsgid_t){ __kgid_val(val) }
111
112#define INVALID_VFSUID VFSUIDT_INIT(INVALID_UID)
113#define INVALID_VFSGID VFSGIDT_INIT(INVALID_GID)
114
115/*
116 * Allow a vfs{g,u}id to be used as a k{g,u}id where we want to compare
117 * whether the mapped value is identical to value of a k{g,u}id.
118 */
119#define AS_KUIDT(val) (kuid_t){ __vfsuid_val(val) }
120#define AS_KGIDT(val) (kgid_t){ __vfsgid_val(val) }
121
122int vfsgid_in_group_p(vfsgid_t vfsgid);
123
124struct mnt_idmap *mnt_idmap_get(struct mnt_idmap *idmap);
125void mnt_idmap_put(struct mnt_idmap *idmap);
126
127vfsuid_t make_vfsuid(struct mnt_idmap *idmap,
128 struct user_namespace *fs_userns, kuid_t kuid);
129
130vfsgid_t make_vfsgid(struct mnt_idmap *idmap,
131 struct user_namespace *fs_userns, kgid_t kgid);
132
133kuid_t from_vfsuid(struct mnt_idmap *idmap,
134 struct user_namespace *fs_userns, vfsuid_t vfsuid);
135
136kgid_t from_vfsgid(struct mnt_idmap *idmap,
137 struct user_namespace *fs_userns, vfsgid_t vfsgid);
138
139/**
140 * vfsuid_has_fsmapping - check whether a vfsuid maps into the filesystem
141 * @idmap: the mount's idmapping
142 * @fs_userns: the filesystem's idmapping
143 * @vfsuid: vfsuid to be mapped
144 *
145 * Check whether @vfsuid has a mapping in the filesystem idmapping. Use this
146 * function to check whether the filesystem idmapping has a mapping for
147 * @vfsuid.
148 *
149 * Return: true if @vfsuid has a mapping in the filesystem, false if not.
150 */
151static inline bool vfsuid_has_fsmapping(struct mnt_idmap *idmap,
152 struct user_namespace *fs_userns,
153 vfsuid_t vfsuid)
154{
155 return uid_valid(uid: from_vfsuid(idmap, fs_userns, vfsuid));
156}
157
158static inline bool vfsuid_has_mapping(struct user_namespace *userns,
159 vfsuid_t vfsuid)
160{
161 return from_kuid(to: userns, AS_KUIDT(vfsuid)) != (uid_t)-1;
162}
163
164/**
165 * vfsuid_into_kuid - convert vfsuid into kuid
166 * @vfsuid: the vfsuid to convert
167 *
168 * This can be used when a vfsuid is committed as a kuid.
169 *
170 * Return: a kuid with the value of @vfsuid
171 */
172static inline kuid_t vfsuid_into_kuid(vfsuid_t vfsuid)
173{
174 return AS_KUIDT(vfsuid);
175}
176
177/**
178 * vfsgid_has_fsmapping - check whether a vfsgid maps into the filesystem
179 * @idmap: the mount's idmapping
180 * @fs_userns: the filesystem's idmapping
181 * @vfsgid: vfsgid to be mapped
182 *
183 * Check whether @vfsgid has a mapping in the filesystem idmapping. Use this
184 * function to check whether the filesystem idmapping has a mapping for
185 * @vfsgid.
186 *
187 * Return: true if @vfsgid has a mapping in the filesystem, false if not.
188 */
189static inline bool vfsgid_has_fsmapping(struct mnt_idmap *idmap,
190 struct user_namespace *fs_userns,
191 vfsgid_t vfsgid)
192{
193 return gid_valid(gid: from_vfsgid(idmap, fs_userns, vfsgid));
194}
195
196static inline bool vfsgid_has_mapping(struct user_namespace *userns,
197 vfsgid_t vfsgid)
198{
199 return from_kgid(to: userns, AS_KGIDT(vfsgid)) != (gid_t)-1;
200}
201
202/**
203 * vfsgid_into_kgid - convert vfsgid into kgid
204 * @vfsgid: the vfsgid to convert
205 *
206 * This can be used when a vfsgid is committed as a kgid.
207 *
208 * Return: a kgid with the value of @vfsgid
209 */
210static inline kgid_t vfsgid_into_kgid(vfsgid_t vfsgid)
211{
212 return AS_KGIDT(vfsgid);
213}
214
215/**
216 * mapped_fsuid - return caller's fsuid mapped according to an idmapping
217 * @idmap: the mount's idmapping
218 * @fs_userns: the filesystem's idmapping
219 *
220 * Use this helper to initialize a new vfs or filesystem object based on
221 * the caller's fsuid. A common example is initializing the i_uid field of
222 * a newly allocated inode triggered by a creation event such as mkdir or
223 * O_CREAT. Other examples include the allocation of quotas for a specific
224 * user.
225 *
226 * Return: the caller's current fsuid mapped up according to @idmap.
227 */
228static inline kuid_t mapped_fsuid(struct mnt_idmap *idmap,
229 struct user_namespace *fs_userns)
230{
231 return from_vfsuid(idmap, fs_userns, VFSUIDT_INIT(current_fsuid()));
232}
233
234/**
235 * mapped_fsgid - return caller's fsgid mapped according to an idmapping
236 * @idmap: the mount's idmapping
237 * @fs_userns: the filesystem's idmapping
238 *
239 * Use this helper to initialize a new vfs or filesystem object based on
240 * the caller's fsgid. A common example is initializing the i_gid field of
241 * a newly allocated inode triggered by a creation event such as mkdir or
242 * O_CREAT. Other examples include the allocation of quotas for a specific
243 * user.
244 *
245 * Return: the caller's current fsgid mapped up according to @idmap.
246 */
247static inline kgid_t mapped_fsgid(struct mnt_idmap *idmap,
248 struct user_namespace *fs_userns)
249{
250 return from_vfsgid(idmap, fs_userns, VFSGIDT_INIT(current_fsgid()));
251}
252
253#endif /* _LINUX_MNT_IDMAPPING_H */
254

source code of linux/include/linux/mnt_idmapping.h