On Fri, 2 Nov 2012 13:21:31 -0700 Tejun Heo <t...@kernel.org> wrote: > Hey, > > On Fri, Nov 02, 2012 at 08:18:24PM +0000, Alan Cox wrote: > > a - there are lots of cases you want to allow only a subset of commands. > > Care to spell them out. At least the cases Paolo listed should be > served by what's described. > > > b - if you are using a BPF filter which is the obvious way to do it then > > the flexibility comes for free without any extra complexity as the kernel > > provides a generic implementation, and even a JIT for complex cases. > > Yeah, sure, but it's all about what tool to use where and maybe it's > my ignorance about the problem space but it's difficult for me to > believe that we need full-blown BPF filter here when this is the only > activity we've got in a decade.
If you look back through the archive you'll find people have been spending a good decade bitching about the lack of filter configurability and trying to get someone else to fix it. The BPF filter is simpler than just about any other implementation because the tools exist and are used for lots of other things and it has an API that is precisely defined as well as kernel calls to run the filter. Some reasons for it - giving people access to parts of disks - allowing access to specific vendor specific commands on certain non-standard CD and DVD drives so they can be used for burning but you can't trash them - giving end users minimal access to things like SMART but only on drives where it is safe - giving a user a SCSI disk or partition to play with but preventing them issuing weird ass commands that can disrupt other devices in the fabric (like drive to drive transfers, some kinds of resets, management commands) - minimising the ability of a VM to do damage if compromised while maximising its raw access to a device Alan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
