From: Ilya Dryomov <idryomov@gmail.com>
Date: Wed, 18 Oct 2017 12:38:38 +0000 (+0200)
Subject: block: move CAP_SYS_ADMIN check in blkdev_roset()
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=bb749b31c25e9b11f8f974baac8d507298ffbb70;p=openwrt%2Fstaging%2Fblogic.git

block: move CAP_SYS_ADMIN check in blkdev_roset()

Check for CAP_SYS_ADMIN before calling into the driver, similar to
blkdev_flushbuf().  This is safer and can spare a check in the driver.

(Currently BLKROSET is overridden by md and rbd, rbd is missing the
check.  md has the check, but it covers a lot more than BLKROSET.)

Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/block/ioctl.c b/block/ioctl.c
index c0fc32bd8ed1..1668506d8ed8 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -443,11 +443,12 @@ static int blkdev_roset(struct block_device *bdev, fmode_t mode,
 {
 	int ret, n;
 
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
 	ret = __blkdev_driver_ioctl(bdev, mode, cmd, arg);
 	if (!is_unrecognized_ioctl(ret))
 		return ret;
-	if (!capable(CAP_SYS_ADMIN))
-		return -EACCES;
 	if (get_user(n, (int __user *)arg))
 		return -EFAULT;
 	set_device_ro(bdev, n);