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ioctl: handle idmapped mounts

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Enable generic ioctls to handle idmapped mounts by passing down the
mount's user namespace. If the initial user namespace is passed nothing
changes so non-idmapped mounts will see identical behavior as before.

Link: https://lore.kernel.org/r/20210121131959.646623-22-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
This commit is contained in:
Christian Brauner 2021-01-21 14:19:40 +01:00
parent b816dd5dde
commit 0f5d220b42
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GPG key ID: 91C61BC06578DCA2
1 changed files with 5 additions and 2 deletions
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7
fs/remap_range.c
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@ -432,13 +432,16 @@ EXPORT_SYMBOL(vfs_clone_file_range);
/* Check whether we are allowed to dedupe the destination file */
static bool allow_file_dedupe(struct file *file)
{
struct user_namespace *mnt_userns = file_mnt_user_ns(file);
struct inode *inode = file_inode(file);
if (capable(CAP_SYS_ADMIN))
return true;
if (file->f_mode & FMODE_WRITE)
return true;
if (uid_eq(current_fsuid(), file_inode(file)->i_uid))
if (uid_eq(current_fsuid(), i_uid_into_mnt(mnt_userns, inode)))
return true;
if (!inode_permission(&init_user_ns, file_inode(file), MAY_WRITE))
if (!inode_permission(mnt_userns, inode, MAY_WRITE))
return true;
return false;
}