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 mnt_idmap; |
9 | struct user_namespace; |
10 | |
11 | extern struct mnt_idmap nop_mnt_idmap; |
12 | extern struct user_namespace init_user_ns; |
13 | |
14 | typedef struct { |
15 | uid_t val; |
16 | } vfsuid_t; |
17 | |
18 | typedef struct { |
19 | gid_t val; |
20 | } vfsgid_t; |
21 | |
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)); |
26 | |
27 | #ifdef CONFIG_MULTIUSER |
28 | static inline uid_t __vfsuid_val(vfsuid_t uid) |
29 | { |
30 | return uid.val; |
31 | } |
32 | |
33 | static inline gid_t __vfsgid_val(vfsgid_t gid) |
34 | { |
35 | return gid.val; |
36 | } |
37 | #else |
38 | static inline uid_t __vfsuid_val(vfsuid_t uid) |
39 | { |
40 | return 0; |
41 | } |
42 | |
43 | static inline gid_t __vfsgid_val(vfsgid_t gid) |
44 | { |
45 | return 0; |
46 | } |
47 | #endif |
48 | |
49 | static inline bool vfsuid_valid(vfsuid_t uid) |
50 | { |
51 | return __vfsuid_val(uid) != (uid_t)-1; |
52 | } |
53 | |
54 | static inline bool vfsgid_valid(vfsgid_t gid) |
55 | { |
56 | return __vfsgid_val(gid) != (gid_t)-1; |
57 | } |
58 | |
59 | static inline bool vfsuid_eq(vfsuid_t left, vfsuid_t right) |
60 | { |
61 | return vfsuid_valid(uid: left) && __vfsuid_val(uid: left) == __vfsuid_val(uid: right); |
62 | } |
63 | |
64 | static inline bool vfsgid_eq(vfsgid_t left, vfsgid_t right) |
65 | { |
66 | return vfsgid_valid(gid: left) && __vfsgid_val(gid: left) == __vfsgid_val(gid: 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 | */ |
79 | static inline bool vfsuid_eq_kuid(vfsuid_t vfsuid, kuid_t kuid) |
80 | { |
81 | return vfsuid_valid(uid: vfsuid) && __vfsuid_val(uid: vfsuid) == __kuid_val(uid: 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 | */ |
94 | static inline bool vfsgid_eq_kgid(vfsgid_t vfsgid, kgid_t kgid) |
95 | { |
96 | return vfsgid_valid(gid: vfsgid) && __vfsgid_val(gid: vfsgid) == __kgid_val(gid: 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 | |
116 | int vfsgid_in_group_p(vfsgid_t vfsgid); |
117 | |
118 | vfsuid_t make_vfsuid(struct mnt_idmap *idmap, |
119 | struct user_namespace *fs_userns, kuid_t kuid); |
120 | |
121 | vfsgid_t make_vfsgid(struct mnt_idmap *idmap, |
122 | struct user_namespace *fs_userns, kgid_t kgid); |
123 | |
124 | kuid_t from_vfsuid(struct mnt_idmap *idmap, |
125 | struct user_namespace *fs_userns, vfsuid_t vfsuid); |
126 | |
127 | kgid_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 | */ |
142 | static inline bool vfsuid_has_fsmapping(struct mnt_idmap *idmap, |
143 | struct user_namespace *fs_userns, |
144 | vfsuid_t vfsuid) |
145 | { |
146 | return uid_valid(uid: from_vfsuid(idmap, fs_userns, vfsuid)); |
147 | } |
148 | |
149 | static inline bool vfsuid_has_mapping(struct user_namespace *userns, |
150 | vfsuid_t vfsuid) |
151 | { |
152 | return from_kuid(to: 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 | */ |
163 | static 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 | */ |
180 | static inline bool vfsgid_has_fsmapping(struct mnt_idmap *idmap, |
181 | struct user_namespace *fs_userns, |
182 | vfsgid_t vfsgid) |
183 | { |
184 | return gid_valid(gid: from_vfsgid(idmap, fs_userns, vfsgid)); |
185 | } |
186 | |
187 | static inline bool vfsgid_has_mapping(struct user_namespace *userns, |
188 | vfsgid_t vfsgid) |
189 | { |
190 | return from_kgid(to: 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 | */ |
201 | static 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 | */ |
219 | static 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 | */ |
238 | static 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 | |
244 | bool check_fsmapping(const struct mnt_idmap *idmap, |
245 | const struct super_block *sb); |
246 | |
247 | #endif /* _LINUX_MNT_IDMAPPING_H */ |
248 | |