Messages in this thread | | | Date | Tue, 31 Mar 2009 09:37:17 -0500 | From | Anthony Liguori <> | Subject | Re: [PATCH 4/4] add ksm kernel shared memory driver. |
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Andrea Arcangeli wrote:
>> the ability to disable KSM. That seems like a security concern to me since >> registering a memory region ought to be an unprivileged action whereas >> enabling/disabling KSM ought to be a privileged action. >> > > sysfs files would then only be writeable by admin, so if we want to > allow only admin to start/stop/tune ksm it'd be enough to plug an > admin capability check in the ioctl to provide equivalent permissions. >
Caps are not very granular unless you introduce a new capability. Furthermore, it's a bit more difficult to associate a capability with a user/group.
With sysfs, you use file based permissions to control the API. It also fits into things like selinux a lot better.
In the very least, if you insist on not using sysfs, you should have a separate character device that's used for control (like /dev/ksmctl).
Regards,
Anthony Liguori
> I could imagine converting the enable/pages_to_scan/sleep_time to > module params and tweaking them through /sys/module/ksm/parameters, > but for "enable" to work that way, we'd need to intercept the write so > we can at least weakup the kksmd daemon, which doesn't seem possible > with /sys/module/ksm/parameters, so in the end if we stick to the > ioctl for registering regions, it seems simpler to use it for > start/stop/tune too. >
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