[PATCH] blkdev: cgroup whitelist permission fix

From: Chris Wright
Date: Fri May 14 2010 - 03:40:40 EST


The cgroup device whitelist code gets confused when trying to grant
permission to a disk partition that is not currently open. Part of
blkdev_open() includes __blkdev_get() on the whole disk. This simply
avoids the cgroup check for the whole disk case when opening a
partition.

https://bugzilla.redhat.com/show_bug.cgi?id=589662

Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
---
fs/block_dev.c | 10 ++++++----
1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 6dcee88..d4d19ac 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1192,10 +1192,12 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
/*
* hooks: /n/, see "layering violations".
*/
- ret = devcgroup_inode_permission(bdev->bd_inode, perm);
- if (ret != 0) {
- bdput(bdev);
- return ret;
+ if (!for_part) {
+ ret = devcgroup_inode_permission(bdev->bd_inode, perm);
+ if (ret != 0) {
+ bdput(bdev);
+ return ret;
+ }
}

lock_kernel();
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