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    SubjectRe: [PATCH 2/3] block: fail SCSI passthrough ioctls on partition devices
    On Thu, Dec 22, 2011 at 10:02 AM, Paolo Bonzini <pbonzini@redhat.com> wrote:
    > Linux allows executing the SG_IO ioctl on a partition or even on an
    > LVM volume, and will pass the command to the underlying block device.
    > This is well-known, but it is also a large security problem when (via
    > Unix permissions, ACLs, SELinux or a combination thereof) a program or
    > user needs to be granted access to a particular partition or logical
    > volume but not to the full device.

    So who actually *does* this in practice?

    > +       /* In particular, rule out all resets and host-specific ioctls.  */
    > +       return -ENOTTY;

    This kind of crazy needs to go away.

    If it's a permission problem, state that. Don't turn it into ENOTTY that then:

    > +               return ret == -ENOTTY ? -ENOIOCTLCMD : ret;

    gets turned into another random error number.

    That's just crazy. No way am I ever applying patches *this* confused
    without some serious explanation. And quite frankly, probably not even
    then.

    If it's a permission issue, return EPERM. Nothing else.

    If returning EPERM causes problems for eject or other user tools,
    explain it. And then just say "ok, we allow eject on a partition, and
    it ejects the disk".

    Linus
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