diff options
Diffstat (limited to 'include/linux/mnt_idmapping.h')
| -rw-r--r-- | include/linux/mnt_idmapping.h | 317 |
1 files changed, 168 insertions, 149 deletions
diff --git a/include/linux/mnt_idmapping.h b/include/linux/mnt_idmapping.h index ee5a217de2a8..e71a6070a8f8 100644 --- a/include/linux/mnt_idmapping.h +++ b/include/linux/mnt_idmapping.h @@ -5,197 +5,216 @@ #include <linux/types.h> #include <linux/uidgid.h> +struct mnt_idmap; struct user_namespace; -/* - * Carries the initial idmapping of 0:0:4294967295 which is an identity - * mapping. This means that {g,u}id 0 is mapped to {g,u}id 0, {g,u}id 1 is - * mapped to {g,u}id 1, [...], {g,u}id 1000 to {g,u}id 1000, [...]. - */ + +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); +} + /** - * initial_idmapping - check whether this is the initial mapping - * @ns: idmapping to check + * vfsuid_eq_kuid - check whether kuid and vfsuid have the same value + * @vfsuid: the vfsuid to compare + * @kuid: the kuid to compare * - * Check whether this is the initial mapping, mapping 0 to 0, 1 to 1, - * [...], 1000 to 1000 [...]. + * Check whether @vfsuid and @kuid have the same values. * - * Return: true if this is the initial mapping, false if not. + * Return: true if @vfsuid and @kuid have the same value, false if not. + * Comparison between two invalid uids returns false. */ -static inline bool initial_idmapping(const struct user_namespace *ns) +static inline bool vfsuid_eq_kuid(vfsuid_t vfsuid, kuid_t kuid) { - return ns == &init_user_ns; + return vfsuid_valid(vfsuid) && __vfsuid_val(vfsuid) == __kuid_val(kuid); } /** - * no_idmapping - check whether we can skip remapping a kuid/gid - * @mnt_userns: the mount's idmapping - * @fs_userns: the filesystem's idmapping + * vfsgid_eq_kgid - check whether kgid and vfsgid have the same value + * @vfsgid: the vfsgid to compare + * @kgid: the kgid to compare * - * This function can be used to check whether a remapping between two - * idmappings is required. - * An idmapped mount is a mount that has an idmapping attached to it that - * is different from the filsystem's idmapping and the initial idmapping. - * If the initial mapping is used or the idmapping of the mount and the - * filesystem are identical no remapping is required. + * Check whether @vfsgid and @kgid have the same values. * - * Return: true if remapping can be skipped, false if not. + * Return: true if @vfsgid and @kgid have the same value, false if not. + * Comparison between two invalid gids returns false. */ -static inline bool no_idmapping(const struct user_namespace *mnt_userns, - const struct user_namespace *fs_userns) +static inline bool vfsgid_eq_kgid(vfsgid_t vfsgid, kgid_t kgid) { - return initial_idmapping(mnt_userns) || mnt_userns == fs_userns; + 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); + /** - * mapped_kuid_fs - map a filesystem kuid into a mnt_userns - * @mnt_userns: the mount's idmapping + * vfsuid_has_fsmapping - check whether a vfsuid maps into the filesystem + * @idmap: the mount's idmapping * @fs_userns: the filesystem's idmapping - * @kuid : kuid to be mapped + * @vfsuid: vfsuid to be mapped * - * Take a @kuid and remap it from @fs_userns into @mnt_userns. Use this - * function when preparing a @kuid to be reported to userspace. + * Check whether @vfsuid has a mapping in the filesystem idmapping. Use this + * function to check whether the filesystem idmapping has a mapping for + * @vfsuid. * - * If no_idmapping() determines that this is not an idmapped mount we can - * simply return @kuid unchanged. - * If initial_idmapping() tells us that the filesystem is not mounted with an - * idmapping we know the value of @kuid won't change when calling - * from_kuid() so we can simply retrieve the value via __kuid_val() - * directly. - * - * Return: @kuid mapped according to @mnt_userns. - * If @kuid has no mapping in either @mnt_userns or @fs_userns INVALID_UID is - * returned. + * Return: true if @vfsuid has a mapping in the filesystem, false if not. */ -static inline kuid_t mapped_kuid_fs(struct user_namespace *mnt_userns, - struct user_namespace *fs_userns, - kuid_t kuid) +static inline bool vfsuid_has_fsmapping(struct mnt_idmap *idmap, + struct user_namespace *fs_userns, + vfsuid_t vfsuid) { - uid_t uid; + return uid_valid(from_vfsuid(idmap, fs_userns, vfsuid)); +} - if (no_idmapping(mnt_userns, fs_userns)) - return kuid; - if (initial_idmapping(fs_userns)) - uid = __kuid_val(kuid); - else - uid = from_kuid(fs_userns, kuid); - if (uid == (uid_t)-1) - return INVALID_UID; - return make_kuid(mnt_userns, uid); +static inline bool vfsuid_has_mapping(struct user_namespace *userns, + vfsuid_t vfsuid) +{ + return from_kuid(userns, AS_KUIDT(vfsuid)) != (uid_t)-1; } /** - * mapped_kgid_fs - map a filesystem kgid into a mnt_userns - * @mnt_userns: the mount's idmapping - * @fs_userns: the filesystem's idmapping - * @kgid : kgid to be mapped - * - * Take a @kgid and remap it from @fs_userns into @mnt_userns. Use this - * function when preparing a @kgid to be reported to userspace. + * vfsuid_into_kuid - convert vfsuid into kuid + * @vfsuid: the vfsuid to convert * - * If no_idmapping() determines that this is not an idmapped mount we can - * simply return @kgid unchanged. - * If initial_idmapping() tells us that the filesystem is not mounted with an - * idmapping we know the value of @kgid won't change when calling - * from_kgid() so we can simply retrieve the value via __kgid_val() - * directly. + * This can be used when a vfsuid is committed as a kuid. * - * Return: @kgid mapped according to @mnt_userns. - * If @kgid has no mapping in either @mnt_userns or @fs_userns INVALID_GID is - * returned. + * Return: a kuid with the value of @vfsuid */ -static inline kgid_t mapped_kgid_fs(struct user_namespace *mnt_userns, - struct user_namespace *fs_userns, - kgid_t kgid) +static inline kuid_t vfsuid_into_kuid(vfsuid_t vfsuid) { - gid_t gid; - - if (no_idmapping(mnt_userns, fs_userns)) - return kgid; - if (initial_idmapping(fs_userns)) - gid = __kgid_val(kgid); - else - gid = from_kgid(fs_userns, kgid); - if (gid == (gid_t)-1) - return INVALID_GID; - return make_kgid(mnt_userns, gid); + return AS_KUIDT(vfsuid); } /** - * mapped_kuid_user - map a user kuid into a mnt_userns - * @mnt_userns: the mount's idmapping + * vfsgid_has_fsmapping - check whether a vfsgid maps into the filesystem + * @idmap: the mount's idmapping * @fs_userns: the filesystem's idmapping - * @kuid : kuid to be mapped - * - * Use the idmapping of @mnt_userns to remap a @kuid into @fs_userns. Use this - * function when preparing a @kuid to be written to disk or inode. + * @vfsgid: vfsgid to be mapped * - * If no_idmapping() determines that this is not an idmapped mount we can - * simply return @kuid unchanged. - * If initial_idmapping() tells us that the filesystem is not mounted with an - * idmapping we know the value of @kuid won't change when calling - * make_kuid() so we can simply retrieve the value via KUIDT_INIT() - * directly. + * 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: @kuid mapped according to @mnt_userns. - * If @kuid has no mapping in either @mnt_userns or @fs_userns INVALID_UID is - * returned. + * Return: true if @vfsgid has a mapping in the filesystem, false if not. */ -static inline kuid_t mapped_kuid_user(struct user_namespace *mnt_userns, - struct user_namespace *fs_userns, - kuid_t kuid) +static inline bool vfsgid_has_fsmapping(struct mnt_idmap *idmap, + struct user_namespace *fs_userns, + vfsgid_t vfsgid) { - uid_t uid; + return gid_valid(from_vfsgid(idmap, fs_userns, vfsgid)); +} - if (no_idmapping(mnt_userns, fs_userns)) - return kuid; - uid = from_kuid(mnt_userns, kuid); - if (uid == (uid_t)-1) - return INVALID_UID; - if (initial_idmapping(fs_userns)) - return KUIDT_INIT(uid); - return make_kuid(fs_userns, uid); +static inline bool vfsgid_has_mapping(struct user_namespace *userns, + vfsgid_t vfsgid) +{ + return from_kgid(userns, AS_KGIDT(vfsgid)) != (gid_t)-1; } /** - * mapped_kgid_user - map a user kgid into a mnt_userns - * @mnt_userns: the mount's idmapping - * @fs_userns: the filesystem's idmapping - * @kgid : kgid to be mapped - * - * Use the idmapping of @mnt_userns to remap a @kgid into @fs_userns. Use this - * function when preparing a @kgid to be written to disk or inode. + * vfsgid_into_kgid - convert vfsgid into kgid + * @vfsgid: the vfsgid to convert * - * If no_idmapping() determines that this is not an idmapped mount we can - * simply return @kgid unchanged. - * If initial_idmapping() tells us that the filesystem is not mounted with an - * idmapping we know the value of @kgid won't change when calling - * make_kgid() so we can simply retrieve the value via KGIDT_INIT() - * directly. + * This can be used when a vfsgid is committed as a kgid. * - * Return: @kgid mapped according to @mnt_userns. - * If @kgid has no mapping in either @mnt_userns or @fs_userns INVALID_GID is - * returned. + * Return: a kgid with the value of @vfsgid */ -static inline kgid_t mapped_kgid_user(struct user_namespace *mnt_userns, - struct user_namespace *fs_userns, - kgid_t kgid) +static inline kgid_t vfsgid_into_kgid(vfsgid_t vfsgid) { - gid_t gid; - - if (no_idmapping(mnt_userns, fs_userns)) - return kgid; - gid = from_kgid(mnt_userns, kgid); - if (gid == (gid_t)-1) - return INVALID_GID; - if (initial_idmapping(fs_userns)) - return KGIDT_INIT(gid); - return make_kgid(fs_userns, gid); + return AS_KGIDT(vfsgid); } /** - * mapped_fsuid - return caller's fsuid mapped up into a mnt_userns - * @mnt_userns: the mount's idmapping + * 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 @@ -204,17 +223,17 @@ static inline kgid_t mapped_kgid_user(struct user_namespace *mnt_userns, * O_CREAT. Other examples include the allocation of quotas for a specific * user. * - * Return: the caller's current fsuid mapped up according to @mnt_userns. + * Return: the caller's current fsuid mapped up according to @idmap. */ -static inline kuid_t mapped_fsuid(struct user_namespace *mnt_userns, +static inline kuid_t mapped_fsuid(struct mnt_idmap *idmap, struct user_namespace *fs_userns) { - return mapped_kuid_user(mnt_userns, fs_userns, current_fsuid()); + return from_vfsuid(idmap, fs_userns, VFSUIDT_INIT(current_fsuid())); } /** - * mapped_fsgid - return caller's fsgid mapped up into a mnt_userns - * @mnt_userns: the mount's idmapping + * 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 @@ -223,12 +242,12 @@ static inline kuid_t mapped_fsuid(struct user_namespace *mnt_userns, * O_CREAT. Other examples include the allocation of quotas for a specific * user. * - * Return: the caller's current fsgid mapped up according to @mnt_userns. + * Return: the caller's current fsgid mapped up according to @idmap. */ -static inline kgid_t mapped_fsgid(struct user_namespace *mnt_userns, +static inline kgid_t mapped_fsgid(struct mnt_idmap *idmap, struct user_namespace *fs_userns) { - return mapped_kgid_user(mnt_userns, fs_userns, current_fsgid()); + return from_vfsgid(idmap, fs_userns, VFSGIDT_INIT(current_fsgid())); } #endif /* _LINUX_MNT_IDMAPPING_H */ |