diff options
| author | Ming Lei <ming.lei@redhat.com> | 2023-01-06 07:17:10 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2023-01-30 01:18:34 +0300 |
| commit | 403ebc877832752da9fc851284fa00ceca7b2fae (patch) | |
| tree | 43b0d642c59f1b0f695d027812c181fe3b26109e /drivers/block | |
| parent | abb864d380854b5427b6b070beb2ebc291ce4d1e (diff) | |
| download | linux-403ebc877832752da9fc851284fa00ceca7b2fae.tar.xz | |
ublk_drv: add module parameter of ublks_max for limiting max allowed ublk dev
Prepare for supporting unprivileged ublk device by limiting max number
ublk devices added. Otherwise too many ublk devices could be added by
un-trusted user, which can be thought as one DoS.
Reviewed-by: ZiyangZhang <ZiyangZhang@linux.alibaba.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230106041711.914434-6-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/block')
| -rw-r--r-- | drivers/block/ublk_drv.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 75033304b900..883f7974d105 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -186,6 +186,15 @@ static wait_queue_head_t ublk_idr_wq; /* wait until one idr is freed */ static DEFINE_MUTEX(ublk_ctl_mutex); +/* + * Max ublk devices allowed to add + * + * It can be extended to one per-user limit in future or even controlled + * by cgroup. + */ +static unsigned int ublks_max = 64; +static unsigned int ublks_added; /* protected by ublk_ctl_mutex */ + static struct miscdevice ublk_misc; static void ublk_dev_param_basic_apply(struct ublk_device *ub) @@ -1441,6 +1450,8 @@ static int ublk_add_chdev(struct ublk_device *ub) ret = cdev_device_add(&ub->cdev, dev); if (ret) goto fail; + + ublks_added++; return 0; fail: put_device(dev); @@ -1483,6 +1494,7 @@ static void ublk_remove(struct ublk_device *ub) cancel_work_sync(&ub->quiesce_work); cdev_device_del(&ub->cdev, &ub->cdev_dev); put_device(&ub->cdev_dev); + ublks_added--; } static struct ublk_device *ublk_get_device_from_id(int idx) @@ -1642,6 +1654,10 @@ static int ublk_ctrl_add_dev(struct io_uring_cmd *cmd) if (ret) return ret; + ret = -EACCES; + if (ublks_added >= ublks_max) + goto out_unlock; + ret = -ENOMEM; ub = kzalloc(sizeof(*ub), GFP_KERNEL); if (!ub) @@ -2095,5 +2111,8 @@ static void __exit ublk_exit(void) module_init(ublk_init); module_exit(ublk_exit); +module_param(ublks_max, int, 0444); +MODULE_PARM_DESC(ublks_max, "max number of ublk devices allowed to add(default: 64)"); + MODULE_AUTHOR("Ming Lei <ming.lei@redhat.com>"); MODULE_LICENSE("GPL"); |