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 mnt_idmap invalid_mnt_idmap; 13 extern struct user_namespace init_user_ns; 14 15 typedef struct { 16 uid_t val; 17 } vfsuid_t; 18 19 typedef struct { 20 gid_t val; 21 } vfsgid_t; 22 23 static_assert(sizeof(vfsuid_t) == sizeof(kuid_t)); 24 static_assert(sizeof(vfsgid_t) == sizeof(kgid_t)); 25 static_assert(offsetof(vfsuid_t, val) == offsetof(kuid_t, val)); 26 static_assert(offsetof(vfsgid_t, val) == offsetof(kgid_t, val)); 27 28 #ifdef CONFIG_MULTIUSER 29 static inline uid_t __vfsuid_val(vfsuid_t uid) 30 { 31 return uid.val; 32 } 33 34 static inline gid_t __vfsgid_val(vfsgid_t gid) 35 { 36 return gid.val; 37 } 38 #else 39 static inline uid_t __vfsuid_val(vfsuid_t uid) 40 { 41 return 0; 42 } 43 44 static inline gid_t __vfsgid_val(vfsgid_t gid) 45 { 46 return 0; 47 } 48 #endif 49 50 static inline bool vfsuid_valid(vfsuid_t uid) 51 { 52 return __vfsuid_val(uid) != (uid_t)-1; 53 } 54 55 static inline bool vfsgid_valid(vfsgid_t gid) 56 { 57 return __vfsgid_val(gid) != (gid_t)-1; 58 } 59 60 static inline bool vfsuid_eq(vfsuid_t left, vfsuid_t right) 61 { 62 return vfsuid_valid(left) && __vfsuid_val(left) == __vfsuid_val(right); 63 } 64 65 static 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 value 72 * @vfsuid: the vfsuid to compare 73 * @kuid: the kuid to compare 74 * 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 */ 80 static 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 value 87 * @vfsgid: the vfsgid to compare 88 * @kgid: the kgid to compare 89 * 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 */ 95 static 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 compare 112 * 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) } 116 117 int vfsgid_in_group_p(vfsgid_t vfsgid); 118 119 struct mnt_idmap *mnt_idmap_get(struct mnt_idmap *idmap); 120 void mnt_idmap_put(struct mnt_idmap *idmap); 121 122 vfsuid_t make_vfsuid(struct mnt_idmap *idmap, 123 struct user_namespace *fs_userns, kuid_t kuid); 124 125 vfsgid_t make_vfsgid(struct mnt_idmap *idmap, 126 struct user_namespace *fs_userns, kgid_t kgid); 127 128 kuid_t from_vfsuid(struct mnt_idmap *idmap, 129 struct user_namespace *fs_userns, vfsuid_t vfsuid); 130 131 kgid_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 filesystem 136 * @idmap: the mount's idmapping 137 * @fs_userns: the filesystem's idmapping 138 * @vfsuid: vfsuid to be mapped 139 * 140 * Check whether @vfsuid has a mapping in the filesystem idmapping. Use this 141 * function to check whether the filesystem idmapping has a mapping for 142 * @vfsuid. 143 * 144 * Return: true if @vfsuid has a mapping in the filesystem, false if not. 145 */ 146 static 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 } 152 153 static 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 kuid 161 * @vfsuid: the vfsuid to convert 162 * 163 * This can be used when a vfsuid is committed as a kuid. 164 * 165 * Return: a kuid with the value of @vfsuid 166 */ 167 static 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 filesystem 174 * @idmap: the mount's idmapping 175 * @fs_userns: the filesystem's idmapping 176 * @vfsgid: vfsgid to be mapped 177 * 178 * Check whether @vfsgid has a mapping in the filesystem idmapping. Use this 179 * function to check whether the filesystem idmapping has a mapping for 180 * @vfsgid. 181 * 182 * Return: true if @vfsgid has a mapping in the filesystem, false if not. 183 */ 184 static 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 } 190 191 static 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 kgid 199 * @vfsgid: the vfsgid to convert 200 * 201 * This can be used when a vfsgid is committed as a kgid. 202 * 203 * Return: a kgid with the value of @vfsgid 204 */ 205 static 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 idmapping 212 * @idmap: the mount's idmapping 213 * @fs_userns: the filesystem's idmapping 214 * 215 * Use this helper to initialize a new vfs or filesystem object based on 216 * the caller's fsuid. A common example is initializing the i_uid field of 217 * a newly allocated inode triggered by a creation event such as mkdir or 218 * O_CREAT. Other examples include the allocation of quotas for a specific 219 * user. 220 * 221 * Return: the caller's current fsuid mapped up according to @idmap. 222 */ 223 static 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 idmapping 231 * @idmap: the mount's idmapping 232 * @fs_userns: the filesystem's idmapping 233 * 234 * Use this helper to initialize a new vfs or filesystem object based on 235 * the caller's fsgid. A common example is initializing the i_gid field of 236 * a newly allocated inode triggered by a creation event such as mkdir or 237 * O_CREAT. Other examples include the allocation of quotas for a specific 238 * user. 239 * 240 * Return: the caller's current fsgid mapped up according to @idmap. 241 */ 242 static 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