On Thu, Jul 25, 2019 at 12:37:11PM -0700, Sagi Grimberg wrote: > > > > > > > > Why do you have a "string" within the kernel and are not using the > > > > > > > normal open() call from userspace on the character device node on the > > > > > > > filesystem in your namespace/mount/whatever? > > > > > > > > > > > > NVMe-OF is configured using configfs. The target is specified by the > > > > > > user writing a path to a configfs attribute. This is the way it works > > > > > > today but with blkdev_get_by_path()[1]. For the passthru code, we need > > > > > > to get a nvme_ctrl instead of a block_device, but the principal is the same. > > > > > > > > > > Why isn't a fd being passed in there instead of a random string? > > > > > > > > I wouldn't know the answer to this but I assume because once we decided > > > > to use configfs, there was no way for the user to pass the kernel an fd. > > > > > > That's definitely not changing. But this is not different than how we > > > use the block device or file configuration, this just happen to need the > > > nvme controller chardev now to issue I/O. > > > > So, as was kind of alluded to in another part of the thread, what are > > you doing about permissions? It seems that any user/group permissions > > are out the window when you have the kernel itself do the opening of the > > char device, right? Why is that ok? You can pass it _any_ character > > device node and away it goes? What if you give it a "wrong" one? Char > > devices are very different from block devices this way. > > We could condition any configfs operation on capable(CAP_NET_ADMIN) to > close that hole for now.. Why that specific permission? And what about the "pass any random char device name" issue? What happens if you pass /dev/random/ as the string? thanks, greg k-h
