namei: make permission helpers idmapped mount aware

The two helpers inode_permission() and generic_permission() are used by
the vfs to perform basic permission checking by verifying that the
caller is privileged over an inode. In order to handle idmapped mounts
we extend the two helpers with an additional user namespace argument.
On idmapped mounts the two helpers will make sure to map the inode
according to the mount's user namespace and then peform identical
permission checks to inode_permission() and generic_permission(). 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/20210121131959.646623-6-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>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
This commit is contained in:
Christian Brauner
2021-01-21 14:19:24 +01:00
parent 0558c1bf5a
commit 47291baa8d
36 changed files with 164 additions and 88 deletions

View File

@@ -873,7 +873,7 @@ static int prepare_open(struct dentry *dentry, int oflag, int ro,
if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
return -EINVAL;
acc = oflag2acc[oflag & O_ACCMODE];
return inode_permission(d_inode(dentry), acc);
return inode_permission(&init_user_ns, d_inode(dentry), acc);
}
static int do_mq_open(const char __user *u_name, int oflag, umode_t mode,