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From:   Damien Le Moal <Damien.LeMoal@wdc.com>
To:     Niklas Cassel <Niklas.Cassel@wdc.com>,
        Jens Axboe <axboe@kernel.dk>, Hannes Reinecke <hare@suse.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Shaun Tancheff <shaun@tancheff.com>
CC:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        Jens Axboe <axboe@fb.com>,
        "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 2/2] blk-zoned: allow BLKREPORTZONE without
 CAP_SYS_ADMIN
Thread-Topic: [PATCH v3 2/2] blk-zoned: allow BLKREPORTZONE without
 CAP_SYS_ADMIN
Thread-Index: AQHXYRgSjUhXBDQMDEqRjMXRF8VrOQ==
Date:   Wed, 16 Jun 2021 02:29:07 +0000
Message-ID: <DM6PR04MB7081B123680E5D318688FF26E70F9@DM6PR04MB7081.namprd04.prod.outlook.com>
References: <20210614122303.154378-1-Niklas.Cassel@wdc.com>
 <20210614122303.154378-3-Niklas.Cassel@wdc.com>
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On 2021/06/14 21:23, Niklas Cassel wrote:=0A=
> From: Niklas Cassel <niklas.cassel@wdc.com>=0A=
> =0A=
> A user space process should not need the CAP_SYS_ADMIN capability set=0A=
> in order to perform a BLKREPORTZONE ioctl.=0A=
> =0A=
> Getting the zone report is required in order to get the write pointer.=0A=
> Neither read() nor write() requires CAP_SYS_ADMIN, so it is reasonable=0A=
> that a user space process that can read/write from/to the device, also=0A=
> can get the write pointer. (Since e.g. writes have to be at the write=0A=
> pointer.)=0A=
> =0A=
> Fixes: 3ed05a987e0f ("blk-zoned: implement ioctls")=0A=
> Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>=0A=
> Cc: stable@vger.kernel.org # v4.10+=0A=
> ---=0A=
> Changes since v2:=0A=
> -Drop the FMODE_READ check. Right now it is possible to open() the device=
 with=0A=
> O_WRONLY and get the zone report from that fd. Therefore adding a FMODE_R=
EAD=0A=
> check on BLKREPORTZONE would break existing applications. Instead, just r=
emove=0A=
> the existing CAP_SYS_ADMIN check.=0A=
> =0A=
>  block/blk-zoned.c | 3 ---=0A=
>  1 file changed, 3 deletions(-)=0A=
> =0A=
> diff --git a/block/blk-zoned.c b/block/blk-zoned.c=0A=
> index 0789e6e9f7db..457eceabed2e 100644=0A=
> --- a/block/blk-zoned.c=0A=
> +++ b/block/blk-zoned.c=0A=
> @@ -288,9 +288,6 @@ int blkdev_report_zones_ioctl(struct block_device *bd=
ev, fmode_t mode,=0A=
>  	if (!blk_queue_is_zoned(q))=0A=
>  		return -ENOTTY;=0A=
>  =0A=
> -	if (!capable(CAP_SYS_ADMIN))=0A=
> -		return -EACCES;=0A=
> -=0A=
>  	if (copy_from_user(&rep, argp, sizeof(struct blk_zone_report)))=0A=
>  		return -EFAULT;=0A=
>  =0A=
> =0A=
=0A=
Looks good.=0A=
=0A=
Reviewed-by: Damien Le Moal <damien.lemoal@dc.com>=0A=
=0A=
-- =0A=
Damien Le Moal=0A=
Western Digital Research=0A=