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fs: move mapping helpers

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The low-level mapping helpers were so far crammed into fs.h. They are
out of place there. The fs.h header should just contain the higher-level
mapping helpers that interact directly with vfs objects such as struct
super_block or struct inode and not the bare mapping helpers. Similarly,
only vfs and specific fs code shall interact with low-level mapping
helpers. And so they won't be made accessible automatically through
regular {g,u}id helpers.

Link: https://lore.kernel.org/r/20211123114227.3124056-3-brauner@kernel.org (v1)
Link: https://lore.kernel.org/r/20211130121032.3753852-3-brauner@kernel.org (v2)
Link: https://lore.kernel.org/r/20211203111707.3901969-3-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
This commit is contained in:
Christian Brauner
2021-12-03 12:16:59 +01:00
parent bb49e9e730
commit a793d79ea3
8 changed files with 108 additions and 90 deletions
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101
include/linux/mnt_idmapping.h Normal file
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@@ -0,0 +1,101 @@
/* 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;
extern struct user_namespace init_user_ns;
/**
* kuid_into_mnt - map a kuid down into a mnt_userns
* @mnt_userns: user namespace of the relevant mount
* @kuid: kuid to be mapped
*
* Return: @kuid mapped according to @mnt_userns.
* If @kuid has no mapping INVALID_UID is returned.
*/
static inline kuid_t kuid_into_mnt(struct user_namespace *mnt_userns,
kuid_t kuid)
{
return make_kuid(mnt_userns, __kuid_val(kuid));
}
/**
* kgid_into_mnt - map a kgid down into a mnt_userns
* @mnt_userns: user namespace of the relevant mount
* @kgid: kgid to be mapped
*
* Return: @kgid mapped according to @mnt_userns.
* If @kgid has no mapping INVALID_GID is returned.
*/
static inline kgid_t kgid_into_mnt(struct user_namespace *mnt_userns,
kgid_t kgid)
{
return make_kgid(mnt_userns, __kgid_val(kgid));
}
/**
* kuid_from_mnt - map a kuid up into a mnt_userns
* @mnt_userns: user namespace of the relevant mount
* @kuid: kuid to be mapped
*
* Return: @kuid mapped up according to @mnt_userns.
* If @kuid has no mapping INVALID_UID is returned.
*/
static inline kuid_t kuid_from_mnt(struct user_namespace *mnt_userns,
kuid_t kuid)
{
return KUIDT_INIT(from_kuid(mnt_userns, kuid));
}
/**
* kgid_from_mnt - map a kgid up into a mnt_userns
* @mnt_userns: user namespace of the relevant mount
* @kgid: kgid to be mapped
*
* Return: @kgid mapped up according to @mnt_userns.
* If @kgid has no mapping INVALID_GID is returned.
*/
static inline kgid_t kgid_from_mnt(struct user_namespace *mnt_userns,
kgid_t kgid)
{
return KGIDT_INIT(from_kgid(mnt_userns, kgid));
}
/**
* mapped_fsuid - return caller's fsuid mapped up into a mnt_userns
* @mnt_userns: user namespace of the relevant mount
*
* 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)
{
return kuid_from_mnt(mnt_userns, current_fsuid());
}
/**
* mapped_fsgid - return caller's fsgid mapped up into a mnt_userns
* @mnt_userns: user namespace of the relevant mount
*
* 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)
{
return kgid_from_mnt(mnt_userns, current_fsgid());
}
#endif /* _LINUX_MNT_IDMAPPING_H */