On 12/11/2018 09:20, Christoph Hellwig wrote: > On Sun, Nov 11, 2018 at 08:42:42AM -0500, Theodore Y. Ts'o wrote: >> It really depends on the security model being used on a particular >> system. I can easily imagine scenarios where userspace is allowed >> full access to the device with respect to read/write/open, but the >> security model doesn't want to allow access to various SCSI commands >> such as firmware upload commands, TCG commads, the >> soon-to-be-standardized Zone Activation Commands (which allow dynamic >> conversion of HDD recording modes between CMR and SMR), etc. > > Well, that's what we have the security_file_ioctl() LSM hook for so that > your security model can arbitrate access to ioctls. Doesn't that have TOC-TOU races by design? Also, what about SG_IO giving write access to files that are only opened read-only (and only have read permissions)? Paolo
