4 ms·

Every kernel (not named seL4) has vulnerabilities. The question is not whether OpenBSD would have been vulnerable to this specific issue, but whether Xen gener

by comex 12y ago

Every kernel (not named seL4) has vulnerabilities. The question is not whether OpenBSD would have been vulnerable to this specific issue, but whether Xen generally has fewer bugs than the OpenBSD kernel - or, for that matter, the Linux kernel, since the grandparent mentioned a bunch of Linux sandboxing technologies. edit: To be absolutely clear, per the grandparent, I'm assuming an environment where unrelated people are running software on the same hardware, either using their own kernel under Xen or user processes under jails.

amluto 12y ago
And if any thinks that the awesome perfection of OpenBSD's authors outweighs the vastly smaller attack surface of something like Xen, I think that they're deluding themselves.
- ris 12y ago
  "the vastly smaller attack surface of something like Xen" Um, citation needed. The exact behaviour of the entire x86 supervisor mode instruction set is not remotely a "small attack surface".
  - amluto 12y ago
    The attack surface of incorrect use of the admittedly complicated x86 privilege transition and protection mechanisms is shared in its entirety by all x86 operating systems (except, to a limited extent, by those that turn off some of these mechanisms, which AFAIK none do).
  - comex 12y ago
    Flipside is that with hardware virtualization, a lot of that behavior is protected in hardware which, for whatever reason, seems to be extremely secure in practice. You don't see a lot of erratum-based exploits... the recent SYSRET bug was severe but only counts somewhat ("instruction does something different than what it does on another vendor's processors, and is technically documented to do so" is bad, but it's not like there was some sequence of instructions that would just get you arbitrary memory access without interacting with the hypervisor).

4 ms·

Every kernel (not named seL4) has vulnerabilities. The question is not whether OpenBSD would have been vulnerable to this specific issue, but whether Xen gener

by comex 12y ago

amluto 12y ago
And if any thinks that the awesome perfection of OpenBSD's authors outweighs the vastly smaller attack surface of something like Xen, I think that they're deluding themselves.
- ris 12y ago
  "the vastly smaller attack surface of something like Xen" Um, citation needed. The exact behaviour of the entire x86 supervisor mode instruction set is not remotely a "small attack surface".
  - amluto 12y ago
    The attack surface of incorrect use of the admittedly complicated x86 privilege transition and protection mechanisms is shared in its entirety by all x86 operating systems (except, to a limited extent, by those that turn off some of these mechanisms, which AFAIK none do).
  - comex 12y ago
    Flipside is that with hardware virtualization, a lot of that behavior is protected in hardware which, for whatever reason, seems to be extremely secure in practice. You don't see a lot of erratum-based exploits... the recent SYSRET bug was severe but only counts somewhat ("instruction does something different than what it does on another vendor's processors, and is technically documented to do so" is bad, but it's not like there was some sequence of instructions that would just get you arbitrary memory access without interacting with the hypervisor).