user namespace: usb: make usb urbs user namespace aware (v2)

Add to the dev_state and alloc_async structures the user namespace
corresponding to the uid and euid.  Pass these to kill_pid_info_as_uid(),
which can then implement a proper, user-namespace-aware uid check.

Changelog:
Sep 20: Per Oleg's suggestion: Instead of caching and passing user namespace,
	uid, and euid each separately, pass a struct cred.
Sep 26: Address Alan Stern's comments: don't define a struct cred at
	usbdev_open(), and take and put a cred at async_completed() to
	ensure it lasts for the duration of kill_pid_info_as_cred().

Signed-off-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 13 insertions, 17 deletions

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 0ca54e22d319..e3beaf229ee3 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -46,6 +46,7 @@
 #include <linux/cdev.h>
 #include <linux/notifier.h>
 #include <linux/security.h>
+#include <linux/user_namespace.h>
 #include <asm/uaccess.h>
 #include <asm/byteorder.h>
 #include <linux/moduleparam.h>
@@ -68,7 +69,7 @@ struct dev_state {
 	wait_queue_head_t wait;     /* wake up if a request completed */
 	unsigned int discsignr;
 	struct pid *disc_pid;
-	uid_t disc_uid, disc_euid;
+	const struct cred *cred;
 	void __user *disccontext;
 	unsigned long ifclaimed;
 	u32 secid;
@@ -79,7 +80,7 @@ struct async {
 	struct list_head asynclist;
 	struct dev_state *ps;
 	struct pid *pid;
-	uid_t uid, euid;
+	const struct cred *cred;
 	unsigned int signr;
 	unsigned int ifnum;
 	void __user *userbuffer;
@@ -248,6 +249,7 @@ static struct async *alloc_async(unsigned int numisoframes)
 static void free_async(struct async *as)
 {
 	put_pid(as->pid);
+	put_cred(as->cred);
 	kfree(as->urb->transfer_buffer);
 	kfree(as->urb->setup_packet);
 	usb_free_urb(as->urb);
@@ -393,9 +395,8 @@ static void async_completed(struct urb *urb)
 	struct dev_state *ps = as->ps;
 	struct siginfo sinfo;
 	struct pid *pid = NULL;
-	uid_t uid = 0;
-	uid_t euid = 0;
 	u32 secid = 0;
+	const struct cred *cred = NULL;
 	int signr;
 
 	spin_lock(&ps->lock);
@@ -408,8 +409,7 @@ static void async_completed(struct urb *urb)
 		sinfo.si_code = SI_ASYNCIO;
 		sinfo.si_addr = as->userurb;
 		pid = get_pid(as->pid);
-		uid = as->uid;
-		euid = as->euid;
+		cred = get_cred(as->cred);
 		secid = as->secid;
 	}
 	snoop(&urb->dev->dev, "urb complete\n");
@@ -423,9 +423,9 @@ static void async_completed(struct urb *urb)
 	spin_unlock(&ps->lock);
 
 	if (signr) {
-		kill_pid_info_as_uid(sinfo.si_signo, &sinfo, pid, uid,
-				      euid, secid);
+		kill_pid_info_as_cred(sinfo.si_signo, &sinfo, pid, cred, secid);
 		put_pid(pid);
+		put_cred(cred);
 	}
 
 	wake_up(&ps->wait);
@@ -672,7 +672,6 @@ static int usbdev_open(struct inode *inode, struct file *file)
 {
 	struct usb_device *dev = NULL;
 	struct dev_state *ps;
-	const struct cred *cred = current_cred();
 	int ret;
 
 	ret = -ENOMEM;
@@ -722,8 +721,7 @@ 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 = cred->uid;
-	ps->disc_euid = cred->euid;
+	ps->cred = get_current_cred();
 	ps->disccontext = NULL;
 	ps->ifclaimed = 0;
 	security_task_getsecid(current, &ps->secid);
@@ -765,6 +763,7 @@ static int usbdev_release(struct inode *inode, struct file *file)
 	usb_unlock_device(dev);
 	usb_put_dev(dev);
 	put_pid(ps->disc_pid);
+	put_cred(ps->cred);
 
 	as = async_getcompleted(ps);
 	while (as) {
@@ -1065,7 +1064,6 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
 	struct usb_host_endpoint *ep;
 	struct async *as;
 	struct usb_ctrlrequest *dr = NULL;
-	const struct cred *cred = current_cred();
 	unsigned int u, totlen, isofrmlen;
 	int ret, ifnum = -1;
 	int is_in;
@@ -1279,8 +1277,7 @@ 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 = cred->uid;
-	as->euid = cred->euid;
+	as->cred = get_current_cred();
 	security_task_getsecid(current, &as->secid);
 	if (!is_in && uurb->buffer_length > 0) {
 		if (copy_from_user(as->urb->transfer_buffer, uurb->buffer,
@@ -1998,9 +1995,8 @@ static void usbdev_remove(struct usb_device *udev)
 			sinfo.si_errno = EPIPE;
 			sinfo.si_code = SI_ASYNCIO;
 			sinfo.si_addr = ps->disccontext;
-			kill_pid_info_as_uid(ps->discsignr, &sinfo,
-					ps->disc_pid, ps->disc_uid,
-					ps->disc_euid, ps->secid);
+			kill_pid_info_as_cred(ps->discsignr, &sinfo,
+					ps->disc_pid, ps->cred, ps->secid);
 		}
 	}
 }