2008-06-05 08:43:17

by Pavel Emelyanov

Subject: [PATCH 1/2] devscgroup: check for device permissions at mount time

Currently even if a task sits in an all-denied cgroup it can still
mount any block device in any mode it wants.

Put a proper check in do_open for block device to prevent this.

Signed-off-by: Pavel Emelyanov <[email protected]>

---
fs/block_dev.c | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index a0e9596..7e1c7a3 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -24,6 +24,7 @@
#include <linux/namei.h>
#include <linux/log2.h>
#include <linux/hardirq.h>
+#include <linux/device_cgroup.h>

#include <asm/uaccess.h>
#include "internal.h"
@@ -933,9 +934,14 @@ static int do_open(struct block_device *bdev, struct file *file, int for_part)
{
struct module *owner = NULL;
struct gendisk *disk;
- int ret = -ENXIO;
+ int ret;
int part;

+ ret = devcgroup_inode_permission(bdev->bd_inode, file->f_mode);
+ if (ret != 0)
+ return ret;
+
+ ret = -ENXIO;
file->f_mapping = bdev->bd_inode->i_mapping;
lock_kernel();
disk = get_gendisk(bdev->bd_dev, &part);
--
1.5.3.4

2008-06-05 17:19:32

by Serge E. Hallyn

Subject: Re: [PATCH 1/2] devscgroup: check for device permissions at mount time

Quoting Pavel Emelyanov ([email protected]):
> Currently even if a task sits in an all-denied cgroup it can still
> mount any block device in any mode it wants.
>
> Put a proper check in do_open for block device to prevent this.
>
> Signed-off-by: Pavel Emelyanov <[email protected]>

Crud. Tested and confirmed, and this patches fixes it.

Acked-by: Serge Hallyn <[email protected]>
Tested-by: Serge Hallyn <[email protected]>

thanks,
-serge

> ---
> fs/block_dev.c | 8 +++++++-
> 1 files changed, 7 insertions(+), 1 deletions(-)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index a0e9596..7e1c7a3 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -24,6 +24,7 @@
> #include <linux/namei.h>
> #include <linux/log2.h>
> #include <linux/hardirq.h>
> +#include <linux/device_cgroup.h>
>
> #include <asm/uaccess.h>
> #include "internal.h"
> @@ -933,9 +934,14 @@ static int do_open(struct block_device *bdev, struct file *file, int for_part)
> {
> struct module *owner = NULL;
> struct gendisk *disk;
> - int ret = -ENXIO;
> + int ret;
> int part;
>
> + ret = devcgroup_inode_permission(bdev->bd_inode, file->f_mode);
> + if (ret != 0)
> + return ret;
> +
> + ret = -ENXIO;
> file->f_mapping = bdev->bd_inode->i_mapping;
> lock_kernel();
> disk = get_gendisk(bdev->bd_dev, &part);
> --
> 1.5.3.4