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
pointer.)
Fixes: 3ed05a987e0f ("blk-zoned: implement ioctls")
Signed-off-by: Niklas Cassel <niklas.cassel@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # 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
