CRED: Wrap task credential accesses in the USB driver

Wrap access to task credentials so that they can be separated more easily from
the task_struct during the introduction of COW creds.

Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id().

Change some task->e?[ug]id to task_e?[ug]id().  In some places it makes more
sense to use RCU directly rather than a convenient wrapper; these will be
addressed by later patches.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: linux-usb@vger.kernel.org
Signed-off-by: James Morris <jmorris@namei.org>

drivers/usb/core/devio.c

@@ -617,8 +617,8 @@ static int usbdev_open(struct inode *inode, struct file *file)
 	init_waitqueue_head(&ps->wait);
 	ps->discsignr = 0;
 	ps->disc_pid = get_pid(task_pid(current));
-	ps->disc_uid = current->uid;
-	ps->disc_euid = current->euid;
+	ps->disc_uid = current_uid();
+	ps->disc_euid = current_euid();
 	ps->disccontext = NULL;
 	ps->ifclaimed = 0;
 	security_task_getsecid(current, &ps->secid);
@@ -1174,8 +1174,8 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
 	as->signr = uurb->signr;
 	as->ifnum = ifnum;
 	as->pid = get_pid(task_pid(current));
-	as->uid = current->uid;
-	as->euid = current->euid;
+	as->uid = current_uid();
+	as->euid = current_euid();
 	security_task_getsecid(current, &as->secid);
 	if (!is_in) {
 		if (copy_from_user(as->urb->transfer_buffer, uurb->buffer,

drivers/usb/core/inode.c

@@ -277,8 +277,8 @@ static struct inode *usbfs_get_inode (struct super_block *sb, int mode, dev_t de
 
 	if (inode) {
 		inode->i_mode = mode;
-		inode->i_uid = current->fsuid;
-		inode->i_gid = current->fsgid;
+		inode->i_uid = current_fsuid();
+		inode->i_gid = current_fsgid();
 		inode->i_blocks = 0;
 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 		switch (mode & S_IFMT) {