2021-08-09 11:54:43

by Niklas Cassel

[permalink] [raw]
Subject: [PATCH v4 2/2] blk-zoned: allow BLKREPORTZONE without CAP_SYS_ADMIN

From: Niklas Cassel <[email protected]>

A user space process should not need the CAP_SYS_ADMIN capability set
in order to perform a BLKREPORTZONE ioctl.

Getting the zone report is required in order to get the write pointer.
Neither read() nor write() requires CAP_SYS_ADMIN, so it is reasonable
that a user space process that can read/write from/to the device, also
can get the write pointer. (Since e.g. writes have to be at the write
pointer.)

Fixes: 3ed05a987e0f ("blk-zoned: implement ioctls")
Signed-off-by: Niklas Cassel <[email protected]>
Reviewed-by: Damien Le Moal <[email protected]>
Reviewed-by: Aravind Ramesh <[email protected]>
Reviewed-by: Adam Manzanares <[email protected]>
Reviewed-by: Himanshu Madhani <[email protected]>
Cc: [email protected] # v4.10+
---
Changes since v3:
-Picked up additional Reviewed-by tags.

block/blk-zoned.c | 3 ---
1 file changed, 3 deletions(-)

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index 8a60dbeb44be..1d0c76c18fc5 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -360,9 +360,6 @@ int blkdev_report_zones_ioctl(struct block_device *bdev, fmode_t mode,
if (!blk_queue_is_zoned(q))
return -ENOTTY;

- if (!capable(CAP_SYS_ADMIN))
- return -EACCES;
-
if (copy_from_user(&rep, argp, sizeof(struct blk_zone_report)))
return -EFAULT;

--
2.31.1


2021-08-09 11:57:40

by Niklas Cassel

[permalink] [raw]
Subject: Re: [PATCH v4 2/2] blk-zoned: allow BLKREPORTZONE without CAP_SYS_ADMIN

On Mon, Aug 09, 2021 at 09:58:17AM +0000, Johannes Thumshirn wrote:
> On 09/08/2021 11:50, Niklas Cassel wrote:
> > From: Niklas Cassel <[email protected]>
> >
> > A user space process should not need the CAP_SYS_ADMIN capability set
> > in order to perform a BLKREPORTZONE ioctl.
> >
> > Getting the zone report is required in order to get the write pointer.
> > Neither read() nor write() requires CAP_SYS_ADMIN, so it is reasonable
> > that a user space process that can read/write from/to the device, also
> > can get the write pointer. (Since e.g. writes have to be at the write
> > pointer.)
> >
> > Fixes: 3ed05a987e0f ("blk-zoned: implement ioctls")
> > Signed-off-by: Niklas Cassel <[email protected]>
> > Reviewed-by: Damien Le Moal <[email protected]>
> Nit: Missing 'w'

Seems like Damien's email had a typo in his original reply:

https://patchwork.kernel.org/project/linux-block/patch/[email protected]/#24252237

Surprised that he doesn't have a shortcut to paste his Reviewed-by tag,
considering the amount of patches that he reviews :)

> > Reviewed-by: Aravind Ramesh <[email protected]>
> > Reviewed-by: Adam Manzanares <[email protected]>
> > Reviewed-by: Himanshu Madhani <[email protected]>
> > Cc: [email protected] # v4.10+
> > ---
> Looks good,
> Reviewed-by: Johannes Thumshirn <[email protected]>
>
>

2021-08-09 14:00:42

by Johannes Thumshirn

[permalink] [raw]
Subject: Re: [PATCH v4 2/2] blk-zoned: allow BLKREPORTZONE without CAP_SYS_ADMIN

On 09/08/2021 11:50, Niklas Cassel wrote:
> From: Niklas Cassel <[email protected]>
>
> A user space process should not need the CAP_SYS_ADMIN capability set
> in order to perform a BLKREPORTZONE ioctl.
>
> Getting the zone report is required in order to get the write pointer.
> Neither read() nor write() requires CAP_SYS_ADMIN, so it is reasonable
> that a user space process that can read/write from/to the device, also
> can get the write pointer. (Since e.g. writes have to be at the write
> pointer.)
>
> Fixes: 3ed05a987e0f ("blk-zoned: implement ioctls")
> Signed-off-by: Niklas Cassel <[email protected]>
> Reviewed-by: Damien Le Moal <[email protected]>
Nit: Missing 'w'
> Reviewed-by: Aravind Ramesh <[email protected]>
> Reviewed-by: Adam Manzanares <[email protected]>
> Reviewed-by: Himanshu Madhani <[email protected]>
> Cc: [email protected] # v4.10+
> ---
Looks good,
Reviewed-by: Johannes Thumshirn <[email protected]>