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;