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From: Niklas Cassel <Niklas.Cassel@wdc.com>
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" <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: [PATCH v3 2/2] blk-zoned: allow BLKREPORTZONE without CAP_SYS_ADMIN
Date: Mon, 14 Jun 2021 12:23:21 +0000	[thread overview]
Message-ID: <20210614122303.154378-3-Niklas.Cassel@wdc.com> (raw)
In-Reply-To: <20210614122303.154378-1-Niklas.Cassel@wdc.com>

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

  parent reply	other threads:[~2021-06-14 12:23 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-14 12:23 [PATCH v3 0/2] allow blk-zoned ioctls " Niklas Cassel
2021-06-14 12:23 ` [PATCH v3 1/2] blk-zoned: allow zone management send operations " Niklas Cassel
2021-06-16 13:42   ` Aravind Ramesh
2021-06-18 14:48   ` Adam Manzanares
2021-06-18 17:56   ` Himanshu Madhani
2021-06-14 12:23 ` Niklas Cassel [this message]
2021-06-16  2:29   ` [PATCH v3 2/2] blk-zoned: allow BLKREPORTZONE " Damien Le Moal
2021-06-16 13:43   ` Aravind Ramesh
2021-06-18 14:49   ` Adam Manzanares
2021-06-18 17:57   ` Himanshu Madhani
2021-06-28  7:20 ` [PATCH v3 0/2] allow blk-zoned ioctls " Niklas Cassel
2021-07-05 11:26   ` Niklas Cassel
2021-07-21  5:04     ` Aravind Ramesh

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