[PATCH V2 2/6] ublk_drv: don't probe partitions if the ubq daemon isn't trusted

Ming Lei
2022-11-24T03:06:17Z

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")
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 30db5e5edac4..a3d776a1c2f5 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