usb, signal, security: only pass the cred, not the secid, to kill_pid_info_as_cred and security_task_kill

commit d178bc3a708f39cbfefc3fab37032d3f2511b4ec ("user namespace: usb:
 make usb urbs user namespace aware (v2)") changed kill_pid_info_as_uid
to kill_pid_info_as_cred, saving and passing a cred structure instead of
uids.  Since the secid can be obtained from the cred, drop the secid fields
from the usb_dev_state and async structures, and drop the secid argument to
kill_pid_info_as_cred.  Replace the secid argument to security_task_kill
with the cred.  Update SELinux, Smack, and AppArmor to use the cred, which
avoids the need for Smack and AppArmor to use a secid at all in this hook.
Further changes to Smack might still be required to take full advantage of
this change, since it should now be possible to perform capability
checking based on the supplied cred.  The changes to Smack and AppArmor
have only been compile-tested.

Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <james.morris@microsoft.com>

1 files changed, 2 insertions, 8 deletions

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index d526595bc959..76e16c5251b9 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -65,7 +65,6 @@ struct usb_dev_state {
 	const struct cred *cred;
 	void __user *disccontext;
 	unsigned long ifclaimed;
-	u32 secid;
 	u32 disabled_bulk_eps;
 	bool privileges_dropped;
 	unsigned long interface_allowed_mask;
@@ -95,7 +94,6 @@ struct async {
 	struct usb_memory *usbm;
 	unsigned int mem_usage;
 	int status;
-	u32 secid;
 	u8 bulk_addr;
 	u8 bulk_status;
 };
@@ -586,7 +584,6 @@ static void async_completed(struct urb *urb)
 	struct usb_dev_state *ps = as->ps;
 	struct siginfo sinfo;
 	struct pid *pid = NULL;
-	u32 secid = 0;
 	const struct cred *cred = NULL;
 	int signr;
 
@@ -602,7 +599,6 @@ static void async_completed(struct urb *urb)
 		sinfo.si_addr = as->userurb;
 		pid = get_pid(as->pid);
 		cred = get_cred(as->cred);
-		secid = as->secid;
 	}
 	snoop(&urb->dev->dev, "urb complete\n");
 	snoop_urb(urb->dev, as->userurb, urb->pipe, urb->actual_length,
@@ -618,7 +614,7 @@ static void async_completed(struct urb *urb)
 	spin_unlock(&ps->lock);
 
 	if (signr) {
-		kill_pid_info_as_cred(sinfo.si_signo, &sinfo, pid, cred, secid);
+		kill_pid_info_as_cred(sinfo.si_signo, &sinfo, pid, cred);
 		put_pid(pid);
 		put_cred(cred);
 	}
@@ -1013,7 +1009,6 @@ static int usbdev_open(struct inode *inode, struct file *file)
 	init_waitqueue_head(&ps->wait);
 	ps->disc_pid = get_pid(task_pid(current));
 	ps->cred = get_current_cred();
-	security_task_getsecid(current, &ps->secid);
 	smp_wmb();
 	list_add_tail(&ps->list, &dev->filelist);
 	file->private_data = ps;
@@ -1727,7 +1722,6 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
 	as->ifnum = ifnum;
 	as->pid = get_pid(task_pid(current));
 	as->cred = get_current_cred();
-	security_task_getsecid(current, &as->secid);
 	snoop_urb(ps->dev, as->userurb, as->urb->pipe,
 			as->urb->transfer_buffer_length, 0, SUBMIT,
 			NULL, 0);
@@ -2617,7 +2611,7 @@ static void usbdev_remove(struct usb_device *udev)
 			sinfo.si_code = SI_ASYNCIO;
 			sinfo.si_addr = ps->disccontext;
 			kill_pid_info_as_cred(ps->discsignr, &sinfo,
-					ps->disc_pid, ps->cred, ps->secid);
+					ps->disc_pid, ps->cred);
 		}
 	}
 }