[PATCH V4 2/6] ublk_drv: don't probe partitions if the ubq daemon isn't trusted

[Ming Lei <ming.lei@redhat.com>]

If any ubq daemon is unprivileged, the ublk char device is allowed
for unprivileged user actually, and we can't trust the current user,
so not probe partitions.

Fixes: 71f28f3136af ("ublk_drv: add io_uring based userspace block driver")
Reviewed-by: ZiyangZhang <ZiyangZhang@linux.alibaba.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/block/ublk_drv.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index f1cad20442df..44c5c1392d40 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -159,6 +159,7 @@ struct ublk_device {
 
 	struct completion	completion;
 	unsigned int		nr_queues_ready;
+	unsigned int		nr_privileged_daemon;
 
 	/*
 	 * Our ubq->daemon may be killed without any notification, so
@@ -1178,6 +1179,9 @@ static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq)
 		ubq->ubq_daemon = current;
 		get_task_struct(ubq->ubq_daemon);
 		ub->nr_queues_ready++;
+
+		if (capable(CAP_SYS_ADMIN))
+			ub->nr_privileged_daemon++;
 	}
 	if (ub->nr_queues_ready == ub->dev_info.nr_hw_queues)
 		complete_all(&ub->completion);
@@ -1534,6 +1538,10 @@ static int ublk_ctrl_start_dev(struct io_uring_cmd *cmd)
 	if (ret)
 		goto out_put_disk;
 
+	/* don't probe partitions if any one ubq daemon is un-trusted */
+	if (ub->nr_privileged_daemon != ub->nr_queues_ready)
+		set_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
+
 	get_device(&ub->cdev_dev);
 	ret = add_disk(disk);
 	if (ret) {
@@ -1935,6 +1943,7 @@ static int ublk_ctrl_start_recovery(struct io_uring_cmd *cmd)
 	/* set to NULL, otherwise new ubq_daemon cannot mmap the io_cmd_buf */
 	ub->mm = NULL;
 	ub->nr_queues_ready = 0;
+	ub->nr_privileged_daemon = 0;
 	init_completion(&ub->completion);
 	ret = 0;
  out_unlock:
-- 
2.31.1