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Diffstat (limited to 'include/linux/mnt_idmapping.h')
| -rw-r--r-- | include/linux/mnt_idmapping.h | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/include/linux/mnt_idmapping.h b/include/linux/mnt_idmapping.h new file mode 100644 index 000000000000..e71a6070a8f8 --- /dev/null +++ b/include/linux/mnt_idmapping.h @@ -0,0 +1,253 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_MNT_IDMAPPING_H +#define _LINUX_MNT_IDMAPPING_H + +#include <linux/types.h> +#include <linux/uidgid.h> + +struct mnt_idmap; +struct user_namespace; + +extern struct mnt_idmap nop_mnt_idmap; +extern struct mnt_idmap invalid_mnt_idmap; +extern struct user_namespace init_user_ns; + +typedef struct { + uid_t val; +} vfsuid_t; + +typedef struct { + gid_t val; +} vfsgid_t; + +static_assert(sizeof(vfsuid_t) == sizeof(kuid_t)); +static_assert(sizeof(vfsgid_t) == sizeof(kgid_t)); +static_assert(offsetof(vfsuid_t, val) == offsetof(kuid_t, val)); +static_assert(offsetof(vfsgid_t, val) == offsetof(kgid_t, val)); + +static inline bool is_valid_mnt_idmap(const struct mnt_idmap *idmap) +{ + return idmap != &nop_mnt_idmap && idmap != &invalid_mnt_idmap; +} + +#ifdef CONFIG_MULTIUSER +static inline uid_t __vfsuid_val(vfsuid_t uid) +{ + return uid.val; +} + +static inline gid_t __vfsgid_val(vfsgid_t gid) +{ + return gid.val; +} +#else +static inline uid_t __vfsuid_val(vfsuid_t uid) +{ + return 0; +} + +static inline gid_t __vfsgid_val(vfsgid_t gid) +{ + return 0; +} +#endif + +static inline bool vfsuid_valid(vfsuid_t uid) +{ + return __vfsuid_val(uid) != (uid_t)-1; +} + +static inline bool vfsgid_valid(vfsgid_t gid) +{ + return __vfsgid_val(gid) != (gid_t)-1; +} + +static inline bool vfsuid_eq(vfsuid_t left, vfsuid_t right) +{ + return vfsuid_valid(left) && __vfsuid_val(left) == __vfsuid_val(right); +} + +static inline bool vfsgid_eq(vfsgid_t left, vfsgid_t right) +{ + return vfsgid_valid(left) && __vfsgid_val(left) == __vfsgid_val(right); +} + +/** + * vfsuid_eq_kuid - check whether kuid and vfsuid have the same value + * @vfsuid: the vfsuid to compare + * @kuid: the kuid to compare + * + * Check whether @vfsuid and @kuid have the same values. + * + * Return: true if @vfsuid and @kuid have the same value, false if not. + * Comparison between two invalid uids returns false. + */ +static inline bool vfsuid_eq_kuid(vfsuid_t vfsuid, kuid_t kuid) +{ + return vfsuid_valid(vfsuid) && __vfsuid_val(vfsuid) == __kuid_val(kuid); +} + +/** + * vfsgid_eq_kgid - check whether kgid and vfsgid have the same value + * @vfsgid: the vfsgid to compare + * @kgid: the kgid to compare + * + * Check whether @vfsgid and @kgid have the same values. + * + * Return: true if @vfsgid and @kgid have the same value, false if not. + * Comparison between two invalid gids returns false. + */ +static inline bool vfsgid_eq_kgid(vfsgid_t vfsgid, kgid_t kgid) +{ + return vfsgid_valid(vfsgid) && __vfsgid_val(vfsgid) == __kgid_val(kgid); +} + +/* + * vfs{g,u}ids are created from k{g,u}ids. + * We don't allow them to be created from regular {u,g}id. + */ +#define VFSUIDT_INIT(val) (vfsuid_t){ __kuid_val(val) } +#define VFSGIDT_INIT(val) (vfsgid_t){ __kgid_val(val) } + +#define INVALID_VFSUID VFSUIDT_INIT(INVALID_UID) +#define INVALID_VFSGID VFSGIDT_INIT(INVALID_GID) + +/* + * Allow a vfs{g,u}id to be used as a k{g,u}id where we want to compare + * whether the mapped value is identical to value of a k{g,u}id. + */ +#define AS_KUIDT(val) (kuid_t){ __vfsuid_val(val) } +#define AS_KGIDT(val) (kgid_t){ __vfsgid_val(val) } + +int vfsgid_in_group_p(vfsgid_t vfsgid); + +struct mnt_idmap *mnt_idmap_get(struct mnt_idmap *idmap); +void mnt_idmap_put(struct mnt_idmap *idmap); + +vfsuid_t make_vfsuid(struct mnt_idmap *idmap, + struct user_namespace *fs_userns, kuid_t kuid); + +vfsgid_t make_vfsgid(struct mnt_idmap *idmap, + struct user_namespace *fs_userns, kgid_t kgid); + +kuid_t from_vfsuid(struct mnt_idmap *idmap, + struct user_namespace *fs_userns, vfsuid_t vfsuid); + +kgid_t from_vfsgid(struct mnt_idmap *idmap, + struct user_namespace *fs_userns, vfsgid_t vfsgid); + +/** + * vfsuid_has_fsmapping - check whether a vfsuid maps into the filesystem + * @idmap: the mount's idmapping + * @fs_userns: the filesystem's idmapping + * @vfsuid: vfsuid to be mapped + * + * Check whether @vfsuid has a mapping in the filesystem idmapping. Use this + * function to check whether the filesystem idmapping has a mapping for + * @vfsuid. + * + * Return: true if @vfsuid has a mapping in the filesystem, false if not. + */ +static inline bool vfsuid_has_fsmapping(struct mnt_idmap *idmap, + struct user_namespace *fs_userns, + vfsuid_t vfsuid) +{ + return uid_valid(from_vfsuid(idmap, fs_userns, vfsuid)); +} + +static inline bool vfsuid_has_mapping(struct user_namespace *userns, + vfsuid_t vfsuid) +{ + return from_kuid(userns, AS_KUIDT(vfsuid)) != (uid_t)-1; +} + +/** + * vfsuid_into_kuid - convert vfsuid into kuid + * @vfsuid: the vfsuid to convert + * + * This can be used when a vfsuid is committed as a kuid. + * + * Return: a kuid with the value of @vfsuid + */ +static inline kuid_t vfsuid_into_kuid(vfsuid_t vfsuid) +{ + return AS_KUIDT(vfsuid); +} + +/** + * vfsgid_has_fsmapping - check whether a vfsgid maps into the filesystem + * @idmap: the mount's idmapping + * @fs_userns: the filesystem's idmapping + * @vfsgid: vfsgid to be mapped + * + * Check whether @vfsgid has a mapping in the filesystem idmapping. Use this + * function to check whether the filesystem idmapping has a mapping for + * @vfsgid. + * + * Return: true if @vfsgid has a mapping in the filesystem, false if not. + */ +static inline bool vfsgid_has_fsmapping(struct mnt_idmap *idmap, + struct user_namespace *fs_userns, + vfsgid_t vfsgid) +{ + return gid_valid(from_vfsgid(idmap, fs_userns, vfsgid)); +} + +static inline bool vfsgid_has_mapping(struct user_namespace *userns, + vfsgid_t vfsgid) +{ + return from_kgid(userns, AS_KGIDT(vfsgid)) != (gid_t)-1; +} + +/** + * vfsgid_into_kgid - convert vfsgid into kgid + * @vfsgid: the vfsgid to convert + * + * This can be used when a vfsgid is committed as a kgid. + * + * Return: a kgid with the value of @vfsgid + */ +static inline kgid_t vfsgid_into_kgid(vfsgid_t vfsgid) +{ + return AS_KGIDT(vfsgid); +} + +/** + * mapped_fsuid - return caller's fsuid mapped according to an idmapping + * @idmap: the mount's idmapping + * @fs_userns: the filesystem's idmapping + * + * Use this helper to initialize a new vfs or filesystem object based on + * the caller's fsuid. A common example is initializing the i_uid field of + * a newly allocated inode triggered by a creation event such as mkdir or + * O_CREAT. Other examples include the allocation of quotas for a specific + * user. + * + * Return: the caller's current fsuid mapped up according to @idmap. + */ +static inline kuid_t mapped_fsuid(struct mnt_idmap *idmap, + struct user_namespace *fs_userns) +{ + return from_vfsuid(idmap, fs_userns, VFSUIDT_INIT(current_fsuid())); +} + +/** + * mapped_fsgid - return caller's fsgid mapped according to an idmapping + * @idmap: the mount's idmapping + * @fs_userns: the filesystem's idmapping + * + * Use this helper to initialize a new vfs or filesystem object based on + * the caller's fsgid. A common example is initializing the i_gid field of + * a newly allocated inode triggered by a creation event such as mkdir or + * O_CREAT. Other examples include the allocation of quotas for a specific + * user. + * + * Return: the caller's current fsgid mapped up according to @idmap. + */ +static inline kgid_t mapped_fsgid(struct mnt_idmap *idmap, + struct user_namespace *fs_userns) +{ + return from_vfsgid(idmap, fs_userns, VFSGIDT_INIT(current_fsgid())); +} + +#endif /* _LINUX_MNT_IDMAPPING_H */ |