On Wed, 26 Sep 2018 11:33:29 +1000 Dave Chinner <david@xxxxxxxxxxxxx> wrote: > On Tue, Sep 25, 2018 at 08:51:50PM -0400, TongZhang wrote: > > Hi, > > > > I'm bringing up this issue again to let of LSM developers know the situation, and would like to know your thoughts. > > Several weeks ago I sent an email to the security list to discuss the issue where > > XFS's ioctl interface can do things like vfs_readlink without asking LSM's > > permission, which we think is kind of weird and this kind of operation should be > > audited by LSM. > > These aren't user interfaces. They are filesystem maintenance and > extension interfaces. They are intended for low level filesystem > utilities that require complete, unrestricted access to the > underlying filesystem via holding CAP_SYSADMIN in the initns. CAP_SYS_ADMIN is meaningless in an environment using a strong LSM set up. So what if I have CAP_SYS_ADMIN ? In a secure environment low level complete unrestricted access to the file system is most definitely something that should be mediated. CAP_SYS_ADMIN is also a bit weird because low level access usually implies you can bypass access controls so you should also check CAP_SYS_DAC ? Alan
