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    Subject[33/67] blkdev: cgroup whitelist permission fix
    2.6.35-stable review patch.  If anyone has any objections, please let us know.

    ------------------

    From: Chris Wright <chrisw@sous-sol.org>

    commit b7300b78d1a87625975a799a109a2f98d77757c8 upstream.

    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.

    Basically, the only ways to reliably allow a cgroup access to a partition
    on a block device when using the whitelist are to 1) also give it access
    to the whole block device or 2) make sure the partition is already open in
    a different context.

    The patch avoids the cgroup check for the whole disk case when opening a
    partition.

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

    Signed-off-by: Chris Wright <chrisw@sous-sol.org>
    Acked-by: Serge E. Hallyn <serue@us.ibm.com>
    Tested-by: Serge E. Hallyn <serue@us.ibm.com>
    Reported-by: Vivek Goyal <vgoyal@redhat.com>
    Cc: Al Viro <viro@ZenIV.linux.org.uk>
    Cc: Christoph Hellwig <hch@infradead.org>
    Cc: "Daniel P. Berrange" <berrange@redhat.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    fs/block_dev.c | 10 ++++++----
    1 file changed, 6 insertions(+), 4 deletions(-)

    --- a/fs/block_dev.c
    +++ b/fs/block_dev.c
    @@ -1339,10 +1339,12 @@ static int __blkdev_get(struct block_dev
    /*
    * 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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