[PATCH v5 2/2] blk-zoned: allow BLKREPORTZONE without CAP_SYS_ADMIN

From: Niklas Cassel
Date: Wed Aug 11 2021 - 07:05:37 EST

From: Niklas Cassel <niklas.cassel@xxxxxxx>

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

Fixes: 3ed05a987e0f ("blk-zoned: implement ioctls")
Signed-off-by: Niklas Cassel <niklas.cassel@xxxxxxx>
Reviewed-by: Damien Le Moal <damien.lemoal@xxxxxxx>
Reviewed-by: Aravind Ramesh <aravind.ramesh@xxxxxxx>
Reviewed-by: Adam Manzanares <a.manzanares@xxxxxxxxxxx>
Reviewed-by: Himanshu Madhani <himanshu.madhani@xxxxxxxxxx>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v4.10+
Changes since v4:
-Picked up additional Reviewed-by tag.
-Corrected Damien's email.

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

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index 8a60dbeb44be..1d0c76c18fc5 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -360,9 +360,6 @@ 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;