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fs: introduce two inode i_{u,g}id initialization helpers

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Give filesystem two little helpers that do the right thing when
initializing the i_uid and i_gid fields on idmapped and non-idmapped
mounts. Filesystems shouldn't have to be concerned with too many
details.

Link: https://lore.kernel.org/r/20210320122623.599086-5-christian.brauner@ubuntu.com
Inspired-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
This commit is contained in:
Christian Brauner 2021-03-20 13:26:24 +01:00
parent 8e5389132a
commit db998553cf
No known key found for this signature in database
GPG key ID: 91C61BC06578DCA2
4 changed files with 32 additions and 4 deletions
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2
fs/ext4/ialloc.c
View file

@ -970,7 +970,7 @@ struct inode *__ext4_new_inode(struct user_namespace *mnt_userns,
i_gid_write(inode, owner[1]);
} else if (test_opt(sb, GRPID)) {
inode->i_mode = mode;
inode->i_uid = mapped_fsuid(mnt_userns);
inode_fsuid_set(inode, mnt_userns);
inode->i_gid = dir->i_gid;
} else
inode_init_owner(mnt_userns, inode, dir, mode);

4
fs/inode.c
View file

@ -2148,7 +2148,7 @@ EXPORT_SYMBOL(init_special_inode);
void inode_init_owner(struct user_namespace *mnt_userns, struct inode *inode,
const struct inode *dir, umode_t mode)
{
inode->i_uid = mapped_fsuid(mnt_userns);
inode_fsuid_set(inode, mnt_userns);
if (dir && dir->i_mode & S_ISGID) {
inode->i_gid = dir->i_gid;
@ -2160,7 +2160,7 @@ void inode_init_owner(struct user_namespace *mnt_userns, struct inode *inode,
!capable_wrt_inode_uidgid(mnt_userns, dir, CAP_FSETID))
mode &= ~S_ISGID;
} else
inode->i_gid = mapped_fsgid(mnt_userns);
inode_fsgid_set(inode, mnt_userns);
inode->i_mode = mode;
}
EXPORT_SYMBOL(inode_init_owner);

2
fs/xfs/xfs_inode.c
View file

@ -812,7 +812,7 @@ xfs_init_new_inode(
if (dir && !(dir->i_mode & S_ISGID) &&
(mp->m_flags & XFS_MOUNT_GRPID)) {
inode->i_uid = mapped_fsuid(mnt_userns);
inode_fsuid_set(inode, mnt_userns);
inode->i_gid = dir->i_gid;
inode->i_mode = mode;
} else {

28
include/linux/fs.h
View file

@ -1692,6 +1692,34 @@ static inline kgid_t mapped_fsgid(struct user_namespace *mnt_userns)
return kgid_from_mnt(mnt_userns, current_fsgid());
}
/**
* inode_fsuid_set - initialize inode's i_uid field with callers fsuid
* @inode: inode to initialize
* @mnt_userns: user namespace of the mount the inode was found from
*
* Initialize the i_uid field of @inode. If the inode was found/created via
* an idmapped mount map the caller's fsuid according to @mnt_users.
*/
static inline void inode_fsuid_set(struct inode *inode,
struct user_namespace *mnt_userns)
{
inode->i_uid = mapped_fsuid(mnt_userns);
}
/**
* inode_fsgid_set - initialize inode's i_gid field with callers fsgid
* @inode: inode to initialize
* @mnt_userns: user namespace of the mount the inode was found from
*
* Initialize the i_gid field of @inode. If the inode was found/created via
* an idmapped mount map the caller's fsgid according to @mnt_users.
*/
static inline void inode_fsgid_set(struct inode *inode,
struct user_namespace *mnt_userns)
{
inode->i_gid = mapped_fsgid(mnt_userns);
}
/**
* fsuidgid_has_mapping() - check whether caller's fsuid/fsgid is mapped
* @sb: the superblock we want a mapping in