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. i.e. they are used to perform filesystem maintenance and extension operations that need to be completely invisible to users from userspace. e.g. online file defragmentation (xfs_fsr), data migration (e.g. HSM products), efficient backup of data (xfsdump), metadata and data scrubbing, online repair, etc. IOWs, I really don't think these interfaces are something the LSMs should be trying to intercept or audit, because they are essentially internal filesystem interfaces used by trusted code and not general user application facing APIs. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
