diff mbox series

[v3,2/2] blk-zoned: allow BLKREPORTZONE without CAP_SYS_ADMIN

Message ID 20210614122303.154378-3-Niklas.Cassel@wdc.com (mailing list archive)
State New, archived
Headers show
Series allow blk-zoned ioctls without CAP_SYS_ADMIN | expand

Commit Message

Niklas Cassel June 14, 2021, 12:23 p.m. UTC 
From: Niklas Cassel <niklas.cassel@wdc.com>

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 <niklas.cassel@wdc.com>
Cc: stable@vger.kernel.org # v4.10+
---
Changes since v2:
-Drop the FMODE_READ check. Right now it is possible to open() the device with
O_WRONLY and get the zone report from that fd. Therefore adding a FMODE_READ
check on BLKREPORTZONE would break existing applications. Instead, just remove
the existing CAP_SYS_ADMIN check.

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

Comments

Damien Le Moal June 16, 2021, 2:29 a.m. UTC | #1 
On 2021/06/14 21:23, Niklas Cassel wrote:
> From: Niklas Cassel <niklas.cassel@wdc.com>
> 
> 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 <niklas.cassel@wdc.com>
> Cc: stable@vger.kernel.org # v4.10+
> ---
> Changes since v2:
> -Drop the FMODE_READ check. Right now it is possible to open() the device with
> O_WRONLY and get the zone report from that fd. Therefore adding a FMODE_READ
> check on BLKREPORTZONE would break existing applications. Instead, just remove
> the existing CAP_SYS_ADMIN check.
> 
>  block/blk-zoned.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/block/blk-zoned.c b/block/blk-zoned.c
> index 0789e6e9f7db..457eceabed2e 100644
> --- a/block/blk-zoned.c
> +++ b/block/blk-zoned.c
> @@ -288,9 +288,6 @@ 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;
>  
> 

Looks good.

Reviewed-by: Damien Le Moal <damien.lemoal@dc.com>
Aravind Ramesh June 16, 2021, 1:43 p.m. UTC | #2 
> -----Original Message-----
> From: Niklas Cassel <Niklas.Cassel@wdc.com>
> Sent: Monday, June 14, 2021 5:53 PM
> To: Jens Axboe <axboe@kernel.dk>; Hannes Reinecke <hare@suse.com>; Martin K.
> Petersen <martin.petersen@oracle.com>; Damien Le Moal
> <Damien.LeMoal@wdc.com>; Shaun Tancheff <shaun@tancheff.com>
> Cc: Damien Le Moal <Damien.LeMoal@wdc.com>; Niklas Cassel
> <Niklas.Cassel@wdc.com>; stable@vger.kernel.org; Jens Axboe <axboe@fb.com>;
> linux-block@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: [PATCH v3 2/2] blk-zoned: allow BLKREPORTZONE without
> CAP_SYS_ADMIN
> 
> From: Niklas Cassel <niklas.cassel@wdc.com>
> 
> 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 <niklas.cassel@wdc.com>
> Cc: stable@vger.kernel.org # v4.10+
> ---
> Changes since v2:
> -Drop the FMODE_READ check. Right now it is possible to open() the device with
> O_WRONLY and get the zone report from that fd. Therefore adding a FMODE_READ
> check on BLKREPORTZONE would break existing applications. Instead, just remove
> the existing CAP_SYS_ADMIN check.
> 
>  block/blk-zoned.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/block/blk-zoned.c b/block/blk-zoned.c index
> 0789e6e9f7db..457eceabed2e 100644
> --- a/block/blk-zoned.c
> +++ b/block/blk-zoned.c
> @@ -288,9 +288,6 @@ 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

Looks good,

Reviewed-by: Aravind Ramesh <aravind.ramesh@wdc.com>
Adam Manzanares June 18, 2021, 2:49 p.m. UTC | #3 
On Mon, Jun 14, 2021 at 12:23:21PM +0000, Niklas Cassel wrote:
> From: Niklas Cassel <niklas.cassel@wdc.com>
> 
> 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 <niklas.cassel@wdc.com>
> Cc: stable@vger.kernel.org # v4.10+
> ---
> Changes since v2:
> -Drop the FMODE_READ check. Right now it is possible to open() the device with
> O_WRONLY and get the zone report from that fd. Therefore adding a FMODE_READ
> check on BLKREPORTZONE would break existing applications. Instead, just remove
> the existing CAP_SYS_ADMIN check.
> 
>  block/blk-zoned.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/block/blk-zoned.c b/block/blk-zoned.c
> index 0789e6e9f7db..457eceabed2e 100644
> --- a/block/blk-zoned.c
> +++ b/block/blk-zoned.c
> @@ -288,9 +288,6 @@ 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

LGTM

Reviewed-by: Adam Manzanares <a.manzanares@samsung.com>
Himanshu Madhani June 18, 2021, 5:57 p.m. UTC | #4 
On 6/14/21 7:23 AM, Niklas Cassel wrote:
> From: Niklas Cassel <niklas.cassel@wdc.com>
> 
> 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 <niklas.cassel@wdc.com>
> Cc: stable@vger.kernel.org # v4.10+
> ---
> Changes since v2:
> -Drop the FMODE_READ check. Right now it is possible to open() the device with
> O_WRONLY and get the zone report from that fd. Therefore adding a FMODE_READ
> check on BLKREPORTZONE would break existing applications. Instead, just remove
> the existing CAP_SYS_ADMIN check.
> 
>   block/blk-zoned.c | 3 ---
>   1 file changed, 3 deletions(-)
> 
> diff --git a/block/blk-zoned.c b/block/blk-zoned.c
> index 0789e6e9f7db..457eceabed2e 100644
> --- a/block/blk-zoned.c
> +++ b/block/blk-zoned.c
> @@ -288,9 +288,6 @@ 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;
>   
> 

Looks Good.

Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
diff mbox series

Patch

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index 0789e6e9f7db..457eceabed2e 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -288,9 +288,6 @@  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;