Date: Mon, 15 Jan 2018 07:52:31 -0500 From: Steven Rostedt <rostedt@...dmis.org> To: Dan Aloni <dan@...nelim.com> Cc: Sergey Senozhatsky <sergey.senozhatsky@...il.com>, linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com, Petr Mladek <pmladek@...e.com>, Linus Torvalds <torvalds@...ux-foundation.org>, Peter Zijlstra <peterz@...radead.org>, Andrew Morton <akpm@...ux-foundation.org>, Kees Cook <keescook@...omium.org> Subject: Re: [PATCHv2 5/7] printk: allow kmsg to be encrypted using public key encryption On Sun, 14 Jan 2018 10:01:08 +0200 Dan Aloni <dan@...nelim.com> wrote: > On Sun, Jan 14, 2018 at 10:48:01AM +0900, Sergey Senozhatsky wrote: > > Ccing Kees, Peter, Andrew, Steven > > > > On (01/13/18 23:34), Dan Aloni wrote: > > > This commit enables the kernel to encrypt the free-form text that > > > is generated by printk() before it is brought up to `dmesg` in > > > userspace. > > > > > > The encryption is made using one of the trusted public keys which > > > are kept built-in inside the kernel. These keys are presently > > > also used for verifying kernel modules and userspace-supplied > > > firmwares. > > > > OK, this is the first time I'm receiving it, yet it's v2 already. > > I'm Cc-ed on only this particular patch, not the entire patch set; > > so it's hard to tell what else is being touched and why, so I'm > > going to start with the basic questions. > > Sorry, here the link to cover letter: > > https://firstname.lastname@example.org/msg1585442.html > > I guess --cc-cover && --to-cover should be default. > > > are you fixing the real problem? that's because you see unhashed > > kernel pointers in dmesg or is there anything else? > > In brief, the problem is that any information leak has the potential > to make exploitation easier. The changes include documentation for > the feature, where more details are provided. > I'm very skeptical that such an approach has much benefit. From the email referenced above: > I am not sure that desktop and power users would like to have their > kernel message encrypted, but there are scenarios such as in mobile > devices, where only the developers, makers of devices, may actually > benefit from access to kernel prints messages, and the users may be > more protected from exploits. Do you have any backing from makers of such devices? I'd like to hear from Google's Android team or whoever that would turn this feature on. I would be hard pressed to add such a feature if it's never used. -- Steve
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