From c1b6205730ef009868fbb68cf4755b20055fcc6c Mon Sep 17 00:00:00 2001 From: Ilya Dryomov Date: Tue, 12 Nov 2019 19:50:55 +0100 Subject: [PATCH] rbd: disallow read-write partitions on images mapped read-only If an image is mapped read-only, don't allow setting its partition(s) to read-write via BLKROSET: with the previous patch all writes to such images are failed anyway. If an image is mapped read-write, its partition(s) can be set to read-only (and back to read-write) as before. Note that at the rbd level the image will remain writeable: anything sent down by the block layer will be executed, including any write from internal kernel users. Signed-off-by: Ilya Dryomov Reviewed-by: Jason Dillaman Reviewed-by: Dongsheng Yang --- drivers/block/rbd.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 02cd2a7df6dd..978e4d846f64 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -706,9 +706,16 @@ static int rbd_ioctl_set_ro(struct rbd_device *rbd_dev, unsigned long arg) if (get_user(ro, (int __user *)arg)) return -EFAULT; - /* Snapshots can't be marked read-write */ - if (rbd_is_snap(rbd_dev) && !ro) - return -EROFS; + /* + * Both images mapped read-only and snapshots can't be marked + * read-write. + */ + if (!ro) { + if (rbd_is_ro(rbd_dev)) + return -EROFS; + + rbd_assert(!rbd_is_snap(rbd_dev)); + } /* Let blkdev_roset() handle it */ return -ENOTTY;