linux-kernel - [PATCH v5 1/2] blk-zoned: allow zone management send operations without CAP_SYS

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Date:   Wed, 11 Aug 2021 11:05:18 +0000
From:   Niklas Cassel <Niklas.Cassel@....com>
To:     Jens Axboe <axboe@...nel.dk>, Hannes Reinecke <hare@...e.com>,
        Damien Le Moal <Damien.LeMoal@....com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Shaun Tancheff <shaun@...cheff.com>
CC:     Damien Le Moal <Damien.LeMoal@....com>,
        Niklas Cassel <Niklas.Cassel@....com>,
        Aravind Ramesh <Aravind.Ramesh@....com>,
        Adam Manzanares <a.manzanares@...sung.com>,
        Himanshu Madhani <himanshu.madhani@...cle.com>,
        Johannes Thumshirn <Johannes.Thumshirn@....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: [PATCH v5 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>
Reviewed-by: Aravind Ramesh <aravind.ramesh@....com>
Reviewed-by: Adam Manzanares <a.manzanares@...sung.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@...cle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@....com>
Cc: stable@...r.kernel.org # v4.10+
---
Changes since v4:
-Picked up additional Reviewed-by tag.

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 86fce751bb17..8a60dbeb44be 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -421,9 +421,6 @@ 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