On Wed, Nov 18, 2015 at 02:10:45PM -0500, Theodore Ts'o wrote: > On Tue, Nov 17, 2015 at 12:34:44PM -0600, Seth Forshee wrote: > > On Tue, Nov 17, 2015 at 05:55:06PM +0000, Al Viro wrote: > > > On Tue, Nov 17, 2015 at 11:25:51AM -0600, Seth Forshee wrote: > > > > > > > Shortly after that I plan to follow with support for ext4. I've been > > > > fuzzing ext4 for a while now and it has held up well, and I'm currently > > > > working on hand-crafted attacks. Ted has commented privately (to others, > > > > not to me personally) that he will fix bugs for such attacks, though I > > > > haven't seen any public comments to that effect. > > > > > > _Static_ attacks, or change-image-under-mounted-fs attacks? > > > > Right now only static attacks, change-image-under-mounted-fs attacks > > will be next. > > I will fix bugs about static attacks. That is, it's interesting to me > that a buggy file system (no matter how it is created), not cause the > kernel to crash --- and privilege escalation attacks tend to be > strongly related to those bugs where we're not doing strong enough > checking. > > Protecting against a malicious user which changes the image under the > file system is a whole other kettle of fish. I am not at all user you > can do this without completely sacrificing performance or making the > code impossible to maintain. So my comments do *not* extend to > protecting against a malicious user who is changing the block device > underneath the kernel. > > If you want to submit patches to make the kernel more robust against > these attacks, I'm certainly willing to look at the patches. But I'm > certainly not guaranteeing that they will go in, and I'm certainly not > promising to fix all vulnerabilities that you might find that are > caused by a malicious block device. Sorry, that's too much buying a > pig in a poke.... Thanks Ted. My plan right now is to explore the possibility of blocking writes to the backing store from userspace while it's mounted. -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
