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 118struct mnt_idmap *mnt_idmap_get(struct mnt_idmap *idmap); 119void mnt_idmap_put(struct mnt_idmap *idmap); 120 121vfsuid_t make_vfsuid(struct mnt_idmap *idmap, 122 struct user_namespace *fs_userns, kuid_t kuid); 123 124vfsgid_t make_vfsgid(struct mnt_idmap *idmap, 125 struct user_namespace *fs_userns, kgid_t kgid); 126 127kuid_t from_vfsuid(struct mnt_idmap *idmap, 128 struct user_namespace *fs_userns, vfsuid_t vfsuid); 129 130kgid_t from_vfsgid(struct mnt_idmap *idmap, 131 struct user_namespace *fs_userns, vfsgid_t vfsgid); 132 133/** 134 * vfsuid_has_fsmapping - check whether a vfsuid maps into the filesystem 135 * @idmap: the mount's idmapping 136 * @fs_userns: the filesystem's idmapping 137 * @vfsuid: vfsuid to be mapped 138 * 139 * Check whether @vfsuid has a mapping in the filesystem idmapping. Use this 140 * function to check whether the filesystem idmapping has a mapping for 141 * @vfsuid. 142 * 143 * Return: true if @vfsuid has a mapping in the filesystem, false if not. 144 */ 145static inline bool vfsuid_has_fsmapping(struct mnt_idmap *idmap, 146 struct user_namespace *fs_userns, 147 vfsuid_t vfsuid) 148{ 149 return uid_valid(from_vfsuid(idmap, fs_userns, vfsuid)); 150} 151 152static inline bool vfsuid_has_mapping(struct user_namespace *userns, 153 vfsuid_t vfsuid) 154{ 155 return from_kuid(userns, AS_KUIDT(vfsuid)) != (uid_t)-1; 156} 157 158/** 159 * vfsuid_into_kuid - convert vfsuid into kuid 160 * @vfsuid: the vfsuid to convert 161 * 162 * This can be used when a vfsuid is committed as a kuid. 163 * 164 * Return: a kuid with the value of @vfsuid 165 */ 166static inline kuid_t vfsuid_into_kuid(vfsuid_t vfsuid) 167{ 168 return AS_KUIDT(vfsuid); 169} 170 171/** 172 * vfsgid_has_fsmapping - check whether a vfsgid maps into the filesystem 173 * @idmap: the mount's idmapping 174 * @fs_userns: the filesystem's idmapping 175 * @vfsgid: vfsgid to be mapped 176 * 177 * Check whether @vfsgid has a mapping in the filesystem idmapping. Use this 178 * function to check whether the filesystem idmapping has a mapping for 179 * @vfsgid. 180 * 181 * Return: true if @vfsgid has a mapping in the filesystem, false if not. 182 */ 183static inline bool vfsgid_has_fsmapping(struct mnt_idmap *idmap, 184 struct user_namespace *fs_userns, 185 vfsgid_t vfsgid) 186{ 187 return gid_valid(from_vfsgid(idmap, fs_userns, vfsgid)); 188} 189 190static inline bool vfsgid_has_mapping(struct user_namespace *userns, 191 vfsgid_t vfsgid) 192{ 193 return from_kgid(userns, AS_KGIDT(vfsgid)) != (gid_t)-1; 194} 195 196/** 197 * vfsgid_into_kgid - convert vfsgid into kgid 198 * @vfsgid: the vfsgid to convert 199 * 200 * This can be used when a vfsgid is committed as a kgid. 201 * 202 * Return: a kgid with the value of @vfsgid 203 */ 204static inline kgid_t vfsgid_into_kgid(vfsgid_t vfsgid) 205{ 206 return AS_KGIDT(vfsgid); 207} 208 209/** 210 * mapped_fsuid - return caller's fsuid mapped according to an idmapping 211 * @idmap: the mount's idmapping 212 * @fs_userns: the filesystem's idmapping 213 * 214 * Use this helper to initialize a new vfs or filesystem object based on 215 * the caller's fsuid. A common example is initializing the i_uid field of 216 * a newly allocated inode triggered by a creation event such as mkdir or 217 * O_CREAT. Other examples include the allocation of quotas for a specific 218 * user. 219 * 220 * Return: the caller's current fsuid mapped up according to @idmap. 221 */ 222static inline kuid_t mapped_fsuid(struct mnt_idmap *idmap, 223 struct user_namespace *fs_userns) 224{ 225 return from_vfsuid(idmap, fs_userns, VFSUIDT_INIT(current_fsuid())); 226} 227 228/** 229 * mapped_fsgid - return caller's fsgid mapped according to an idmapping 230 * @idmap: the mount's idmapping 231 * @fs_userns: the filesystem's idmapping 232 * 233 * Use this helper to initialize a new vfs or filesystem object based on 234 * the caller's fsgid. A common example is initializing the i_gid field of 235 * a newly allocated inode triggered by a creation event such as mkdir or 236 * O_CREAT. Other examples include the allocation of quotas for a specific 237 * user. 238 * 239 * Return: the caller's current fsgid mapped up according to @idmap. 240 */ 241static inline kgid_t mapped_fsgid(struct mnt_idmap *idmap, 242 struct user_namespace *fs_userns) 243{ 244 return from_vfsgid(idmap, fs_userns, VFSGIDT_INIT(current_fsgid())); 245} 246 247#endif /* _LINUX_MNT_IDMAPPING_H */ 248