linux-kernel - RE: [PATCH v3 1/2] blk-zoned: allow zone management send operations without CAP_SYS

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Date:   Wed, 16 Jun 2021 13:42:47 +0000
From:   Aravind Ramesh <Aravind.Ramesh@....com>
To:     Niklas Cassel <Niklas.Cassel@....com>,
        Jens Axboe <axboe@...nel.dk>,
        Damien Le Moal <Damien.LeMoal@....com>,
        Shaun Tancheff <shaun@...cheff.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Hannes Reinecke <hare@...e.com>
CC:     Damien Le Moal <Damien.LeMoal@....com>,
        Niklas Cassel <Niklas.Cassel@....com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Jens Axboe <axboe@...com>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v3 1/2] blk-zoned: allow zone management send operations
 without CAP_SYS_ADMIN



> -----Original Message-----
> From: Niklas Cassel <Niklas.Cassel@....com>
> Sent: Monday, June 14, 2021 5:53 PM
> To: Jens Axboe <axboe@...nel.dk>; Damien Le Moal <Damien.LeMoal@....com>;
> Shaun Tancheff <shaun@...cheff.com>; Martin K. Petersen
> <martin.petersen@...cle.com>; Hannes Reinecke <hare@...e.com>
> Cc: Damien Le Moal <Damien.LeMoal@....com>; Niklas Cassel
> <Niklas.Cassel@....com>; stable@...r.kernel.org; Jens Axboe <axboe@...com>;
> linux-block@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: [PATCH v3 1/2] blk-zoned: allow zone management send operations
> without CAP_SYS_ADMIN
> 
> From: Niklas Cassel <niklas.cassel@....com>
> 
> Zone management send operations (BLKRESETZONE, BLKOPENZONE,
> BLKCLOSEZONE and BLKFINISHZONE) should be allowed under the same permissions
> as write().
> (write() does not require CAP_SYS_ADMIN).
> 
> Additionally, other ioctls like BLKSECDISCARD and BLKZEROOUT only check if the fd
> was successfully opened with FMODE_WRITE.
> (They do not require CAP_SYS_ADMIN).
> 
> Currently, zone management send operations require both CAP_SYS_ADMIN and
> that the fd was successfully opened with FMODE_WRITE.
> 
> Remove the CAP_SYS_ADMIN requirement, so that zone management send
> operations match the access control requirement of write(), BLKSECDISCARD and
> BLKZEROOUT.
> 
> Fixes: 3ed05a987e0f ("blk-zoned: implement ioctls")
> Signed-off-by: Niklas Cassel <niklas.cassel@....com>
> Reviewed-by: Damien Le Moal <damien.lemoal@....com>
> Cc: stable@...r.kernel.org # v4.10+
> ---
> Changes since v2:
> -None
> 
> Note to backporter:
> Function was added as blkdev_reset_zones_ioctl() in v4.10.
> Function was renamed to blkdev_zone_mgmt_ioctl() in v5.5.
> The patch is valid both before and after the function rename.
> 
>  block/blk-zoned.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/block/blk-zoned.c b/block/blk-zoned.c index
> 250cb76ee615..0789e6e9f7db 100644
> --- a/block/blk-zoned.c
> +++ b/block/blk-zoned.c
> @@ -349,9 +349,6 @@ int blkdev_zone_mgmt_ioctl(struct block_device *bdev,
> fmode_t mode,
>  	if (!blk_queue_is_zoned(q))
>  		return -ENOTTY;
> 
> -	if (!capable(CAP_SYS_ADMIN))
> -		return -EACCES;
> -
>  	if (!(mode & FMODE_WRITE))
>  		return -EBADF;
> 
> --
> 2.31.1

Looks good,

Reviewed-by: Aravind Ramesh <aravind.ramesh@....com>