linuxdebug/include/linux/mnt_idmapping.h

476 lines
14 KiB
C

/* 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 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 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));
#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) }
#ifdef CONFIG_MULTIUSER
/**
* vfsgid_in_group_p() - check whether a vfsuid matches the caller's groups
* @vfsgid: the mnt gid to match
*
* This function can be used to determine whether @vfsuid matches any of the
* caller's groups.
*
* Return: 1 if vfsuid matches caller's groups, 0 if not.
*/
static inline int vfsgid_in_group_p(vfsgid_t vfsgid)
{
return in_group_p(AS_KGIDT(vfsgid));
}
#else
static inline int vfsgid_in_group_p(vfsgid_t vfsgid)
{
return 1;
}
#endif
/**
* initial_idmapping - check whether this is the initial mapping
* @ns: idmapping to check
*
* Check whether this is the initial mapping, mapping 0 to 0, 1 to 1,
* [...], 1000 to 1000 [...].
*
* Return: true if this is the initial mapping, false if not.
*/
static inline bool initial_idmapping(const struct user_namespace *ns)
{
return ns == &init_user_ns;
}
/**
* no_idmapping - check whether we can skip remapping a kuid/gid
* @mnt_userns: the mount's idmapping
* @fs_userns: the filesystem's idmapping
*
* 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.
*
* Return: true if remapping can be skipped, false if not.
*/
static inline bool no_idmapping(const struct user_namespace *mnt_userns,
const struct user_namespace *fs_userns)
{
return initial_idmapping(mnt_userns) || mnt_userns == fs_userns;
}
/**
* make_vfsuid - map a filesystem kuid into a mnt_userns
* @mnt_userns: the mount's idmapping
* @fs_userns: the filesystem's idmapping
* @kuid : kuid 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.
*
* 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.
*/
static inline vfsuid_t make_vfsuid(struct user_namespace *mnt_userns,
struct user_namespace *fs_userns,
kuid_t kuid)
{
uid_t uid;
if (no_idmapping(mnt_userns, fs_userns))
return VFSUIDT_INIT(kuid);
if (initial_idmapping(fs_userns))
uid = __kuid_val(kuid);
else
uid = from_kuid(fs_userns, kuid);
if (uid == (uid_t)-1)
return INVALID_VFSUID;
return VFSUIDT_INIT(make_kuid(mnt_userns, uid));
}
static inline kuid_t mapped_kuid_fs(struct user_namespace *mnt_userns,
struct user_namespace *fs_userns,
kuid_t kuid)
{
return AS_KUIDT(make_vfsuid(mnt_userns, fs_userns, kuid));
}
/**
* make_vfsgid - 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.
*
* 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.
*
* Return: @kgid mapped according to @mnt_userns.
* If @kgid has no mapping in either @mnt_userns or @fs_userns INVALID_GID is
* returned.
*/
static inline vfsgid_t make_vfsgid(struct user_namespace *mnt_userns,
struct user_namespace *fs_userns,
kgid_t kgid)
{
gid_t gid;
if (no_idmapping(mnt_userns, fs_userns))
return VFSGIDT_INIT(kgid);
if (initial_idmapping(fs_userns))
gid = __kgid_val(kgid);
else
gid = from_kgid(fs_userns, kgid);
if (gid == (gid_t)-1)
return INVALID_VFSGID;
return VFSGIDT_INIT(make_kgid(mnt_userns, gid));
}
static inline kgid_t mapped_kgid_fs(struct user_namespace *mnt_userns,
struct user_namespace *fs_userns,
kgid_t kgid)
{
return AS_KGIDT(make_vfsgid(mnt_userns, fs_userns, kgid));
}
/**
* from_vfsuid - map a vfsuid into the filesystem idmapping
* @mnt_userns: the mount's idmapping
* @fs_userns: the filesystem's idmapping
* @vfsuid : vfsuid to be mapped
*
* Map @vfsuid into the filesystem idmapping. This function has to be used in
* order to e.g. write @vfsuid to inode->i_uid.
*
* Return: @vfsuid mapped into the filesystem idmapping
*/
static inline kuid_t from_vfsuid(struct user_namespace *mnt_userns,
struct user_namespace *fs_userns,
vfsuid_t vfsuid)
{
uid_t uid;
if (no_idmapping(mnt_userns, fs_userns))
return AS_KUIDT(vfsuid);
uid = from_kuid(mnt_userns, AS_KUIDT(vfsuid));
if (uid == (uid_t)-1)
return INVALID_UID;
if (initial_idmapping(fs_userns))
return KUIDT_INIT(uid);
return make_kuid(fs_userns, uid);
}
/**
* mapped_kuid_user - map a user kuid into a mnt_userns
* @mnt_userns: 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.
*
* 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.
*
* Return: @kuid mapped according to @mnt_userns.
* If @kuid has no mapping in either @mnt_userns or @fs_userns INVALID_UID is
* returned.
*/
static inline kuid_t mapped_kuid_user(struct user_namespace *mnt_userns,
struct user_namespace *fs_userns,
kuid_t kuid)
{
return from_vfsuid(mnt_userns, fs_userns, VFSUIDT_INIT(kuid));
}
/**
* vfsuid_has_fsmapping - check whether a vfsuid maps into the filesystem
* @mnt_userns: 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 user_namespace *mnt_userns,
struct user_namespace *fs_userns,
vfsuid_t vfsuid)
{
return uid_valid(from_vfsuid(mnt_userns, fs_userns, vfsuid));
}
/**
* 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);
}
/**
* from_vfsgid - map a vfsgid into the filesystem idmapping
* @mnt_userns: the mount's idmapping
* @fs_userns: the filesystem's idmapping
* @vfsgid : vfsgid to be mapped
*
* Map @vfsgid into the filesystem idmapping. This function has to be used in
* order to e.g. write @vfsgid to inode->i_gid.
*
* Return: @vfsgid mapped into the filesystem idmapping
*/
static inline kgid_t from_vfsgid(struct user_namespace *mnt_userns,
struct user_namespace *fs_userns,
vfsgid_t vfsgid)
{
gid_t gid;
if (no_idmapping(mnt_userns, fs_userns))
return AS_KGIDT(vfsgid);
gid = from_kgid(mnt_userns, AS_KGIDT(vfsgid));
if (gid == (gid_t)-1)
return INVALID_GID;
if (initial_idmapping(fs_userns))
return KGIDT_INIT(gid);
return make_kgid(fs_userns, gid);
}
/**
* 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.
*
* 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.
*
* Return: @kgid mapped according to @mnt_userns.
* If @kgid has no mapping in either @mnt_userns or @fs_userns INVALID_GID is
* returned.
*/
static inline kgid_t mapped_kgid_user(struct user_namespace *mnt_userns,
struct user_namespace *fs_userns,
kgid_t kgid)
{
return from_vfsgid(mnt_userns, fs_userns, VFSGIDT_INIT(kgid));
}
/**
* vfsgid_has_fsmapping - check whether a vfsgid maps into the filesystem
* @mnt_userns: 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 user_namespace *mnt_userns,
struct user_namespace *fs_userns,
vfsgid_t vfsgid)
{
return gid_valid(from_vfsgid(mnt_userns, fs_userns, vfsgid));
}
/**
* 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 up into a mnt_userns
* @mnt_userns: 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 @mnt_userns.
*/
static inline kuid_t mapped_fsuid(struct user_namespace *mnt_userns,
struct user_namespace *fs_userns)
{
return from_vfsuid(mnt_userns, fs_userns,
VFSUIDT_INIT(current_fsuid()));
}
/**
* mapped_fsgid - return caller's fsgid mapped up into a mnt_userns
* @mnt_userns: 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 @mnt_userns.
*/
static inline kgid_t mapped_fsgid(struct user_namespace *mnt_userns,
struct user_namespace *fs_userns)
{
return from_vfsgid(mnt_userns, fs_userns,
VFSGIDT_INIT(current_fsgid()));
}
#endif /* _LINUX_MNT_IDMAPPING_H */