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1/* SPDX-License-Identifier: GPL-2.0 */2#ifndef _LINUX_MNT_IDMAPPING_H3#define _LINUX_MNT_IDMAPPING_H4 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 28#ifdef CONFIG_MULTIUSER29static inline uid_t __vfsuid_val(vfsuid_t uid)30{31 return uid.val;32}33 34static inline gid_t __vfsgid_val(vfsgid_t gid)35{36 return gid.val;37}38#else39static inline uid_t __vfsuid_val(vfsuid_t uid)40{41 return 0;42}43 44static inline gid_t __vfsgid_val(vfsgid_t gid)45{46 return 0;47}48#endif49 50static inline bool vfsuid_valid(vfsuid_t uid)51{52 return __vfsuid_val(uid) != (uid_t)-1;53}54 55static inline bool vfsgid_valid(vfsgid_t gid)56{57 return __vfsgid_val(gid) != (gid_t)-1;58}59 60static inline bool vfsuid_eq(vfsuid_t left, vfsuid_t right)61{62 return vfsuid_valid(left) && __vfsuid_val(left) == __vfsuid_val(right);63}64 65static inline bool vfsgid_eq(vfsgid_t left, vfsgid_t right)66{67 return vfsgid_valid(left) && __vfsgid_val(left) == __vfsgid_val(right);68}69 70/**71 * vfsuid_eq_kuid - check whether kuid and vfsuid have the same value72 * @vfsuid: the vfsuid to compare73 * @kuid: the kuid to compare74 *75 * Check whether @vfsuid and @kuid have the same values.76 *77 * Return: true if @vfsuid and @kuid have the same value, false if not.78 * Comparison between two invalid uids returns false.79 */80static inline bool vfsuid_eq_kuid(vfsuid_t vfsuid, kuid_t kuid)81{82 return vfsuid_valid(vfsuid) && __vfsuid_val(vfsuid) == __kuid_val(kuid);83}84 85/**86 * vfsgid_eq_kgid - check whether kgid and vfsgid have the same value87 * @vfsgid: the vfsgid to compare88 * @kgid: the kgid to compare89 *90 * Check whether @vfsgid and @kgid have the same values.91 *92 * Return: true if @vfsgid and @kgid have the same value, false if not.93 * Comparison between two invalid gids returns false.94 */95static inline bool vfsgid_eq_kgid(vfsgid_t vfsgid, kgid_t kgid)96{97 return vfsgid_valid(vfsgid) && __vfsgid_val(vfsgid) == __kgid_val(kgid);98}99 100/*101 * vfs{g,u}ids are created from k{g,u}ids.102 * We don't allow them to be created from regular {u,g}id.103 */104#define VFSUIDT_INIT(val) (vfsuid_t){ __kuid_val(val) }105#define VFSGIDT_INIT(val) (vfsgid_t){ __kgid_val(val) }106 107#define INVALID_VFSUID VFSUIDT_INIT(INVALID_UID)108#define INVALID_VFSGID VFSGIDT_INIT(INVALID_GID)109 110/*111 * Allow a vfs{g,u}id to be used as a k{g,u}id where we want to compare112 * whether the mapped value is identical to value of a k{g,u}id.113 */114#define AS_KUIDT(val) (kuid_t){ __vfsuid_val(val) }115#define AS_KGIDT(val) (kgid_t){ __vfsgid_val(val) }116 117int vfsgid_in_group_p(vfsgid_t vfsgid);118 119struct mnt_idmap *mnt_idmap_get(struct mnt_idmap *idmap);120void mnt_idmap_put(struct mnt_idmap *idmap);121 122vfsuid_t make_vfsuid(struct mnt_idmap *idmap,123 struct user_namespace *fs_userns, kuid_t kuid);124 125vfsgid_t make_vfsgid(struct mnt_idmap *idmap,126 struct user_namespace *fs_userns, kgid_t kgid);127 128kuid_t from_vfsuid(struct mnt_idmap *idmap,129 struct user_namespace *fs_userns, vfsuid_t vfsuid);130 131kgid_t from_vfsgid(struct mnt_idmap *idmap,132 struct user_namespace *fs_userns, vfsgid_t vfsgid);133 134/**135 * vfsuid_has_fsmapping - check whether a vfsuid maps into the filesystem136 * @idmap: the mount's idmapping137 * @fs_userns: the filesystem's idmapping138 * @vfsuid: vfsuid to be mapped139 *140 * Check whether @vfsuid has a mapping in the filesystem idmapping. Use this141 * function to check whether the filesystem idmapping has a mapping for142 * @vfsuid.143 *144 * Return: true if @vfsuid has a mapping in the filesystem, false if not.145 */146static inline bool vfsuid_has_fsmapping(struct mnt_idmap *idmap,147 struct user_namespace *fs_userns,148 vfsuid_t vfsuid)149{150 return uid_valid(from_vfsuid(idmap, fs_userns, vfsuid));151}152 153static inline bool vfsuid_has_mapping(struct user_namespace *userns,154 vfsuid_t vfsuid)155{156 return from_kuid(userns, AS_KUIDT(vfsuid)) != (uid_t)-1;157}158 159/**160 * vfsuid_into_kuid - convert vfsuid into kuid161 * @vfsuid: the vfsuid to convert162 *163 * This can be used when a vfsuid is committed as a kuid.164 *165 * Return: a kuid with the value of @vfsuid166 */167static inline kuid_t vfsuid_into_kuid(vfsuid_t vfsuid)168{169 return AS_KUIDT(vfsuid);170}171 172/**173 * vfsgid_has_fsmapping - check whether a vfsgid maps into the filesystem174 * @idmap: the mount's idmapping175 * @fs_userns: the filesystem's idmapping176 * @vfsgid: vfsgid to be mapped177 *178 * Check whether @vfsgid has a mapping in the filesystem idmapping. Use this179 * function to check whether the filesystem idmapping has a mapping for180 * @vfsgid.181 *182 * Return: true if @vfsgid has a mapping in the filesystem, false if not.183 */184static inline bool vfsgid_has_fsmapping(struct mnt_idmap *idmap,185 struct user_namespace *fs_userns,186 vfsgid_t vfsgid)187{188 return gid_valid(from_vfsgid(idmap, fs_userns, vfsgid));189}190 191static inline bool vfsgid_has_mapping(struct user_namespace *userns,192 vfsgid_t vfsgid)193{194 return from_kgid(userns, AS_KGIDT(vfsgid)) != (gid_t)-1;195}196 197/**198 * vfsgid_into_kgid - convert vfsgid into kgid199 * @vfsgid: the vfsgid to convert200 *201 * This can be used when a vfsgid is committed as a kgid.202 *203 * Return: a kgid with the value of @vfsgid204 */205static inline kgid_t vfsgid_into_kgid(vfsgid_t vfsgid)206{207 return AS_KGIDT(vfsgid);208}209 210/**211 * mapped_fsuid - return caller's fsuid mapped according to an idmapping212 * @idmap: the mount's idmapping213 * @fs_userns: the filesystem's idmapping214 *215 * Use this helper to initialize a new vfs or filesystem object based on216 * the caller's fsuid. A common example is initializing the i_uid field of217 * a newly allocated inode triggered by a creation event such as mkdir or218 * O_CREAT. Other examples include the allocation of quotas for a specific219 * user.220 *221 * Return: the caller's current fsuid mapped up according to @idmap.222 */223static inline kuid_t mapped_fsuid(struct mnt_idmap *idmap,224 struct user_namespace *fs_userns)225{226 return from_vfsuid(idmap, fs_userns, VFSUIDT_INIT(current_fsuid()));227}228 229/**230 * mapped_fsgid - return caller's fsgid mapped according to an idmapping231 * @idmap: the mount's idmapping232 * @fs_userns: the filesystem's idmapping233 *234 * Use this helper to initialize a new vfs or filesystem object based on235 * the caller's fsgid. A common example is initializing the i_gid field of236 * a newly allocated inode triggered by a creation event such as mkdir or237 * O_CREAT. Other examples include the allocation of quotas for a specific238 * user.239 *240 * Return: the caller's current fsgid mapped up according to @idmap.241 */242static inline kgid_t mapped_fsgid(struct mnt_idmap *idmap,243 struct user_namespace *fs_userns)244{245 return from_vfsgid(idmap, fs_userns, VFSGIDT_INIT(current_fsgid()));246}247 248#endif /* _LINUX_MNT_IDMAPPING_H */249