From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: "Tobin C. Harding" <me@tobin.cc>
Cc: kernel-hardening@lists.openwall.com,
"Jason A. Donenfeld" <Jason@zx2c4.com>,
"Theodore Ts'o" <tytso@mit.edu>,
Linus Torvalds <torvalds@linux-foundation.org>,
Kees Cook <keescook@chromium.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Tycho Andersen <tycho@docker.com>,
"Roberts, William C" <william.c.roberts@intel.com>,
Tejun Heo <tj@kernel.org>,
Jordan Glover <Golden_Miller83@protonmail.ch>,
Greg KH <gregkh@linuxfoundation.org>,
Petr Mladek <pmladek@suse.com>, Joe Perches <joe@perches.com>,
Ian Campbell <ijc@hellion.org.uk>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <wilal.deacon@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Chris Fries <cfries@google.com>,
Dave Weinstein <olorin@google.com>,
Daniel Micay <danielmicay@gmail.com>,
Djalal Harouni <tixxdz@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH V8 0/2] printk: hash addresses printed with %p
Date: Fri, 27 Oct 2017 22:33:01 +0900 [thread overview]
Message-ID: <20171027133301.GA612@tigerII.localdomain> (raw)
In-Reply-To: <1508986436-31966-1-git-send-email-me@tobin.cc>
On (10/26/17 13:53), Tobin C. Harding wrote:
> Currently there are many places in the kernel where addresses are being
> printed using an unadorned %p. Kernel pointers should be printed using
> %pK allowing some control via the kptr_restrict sysctl. Exposing
> addresses gives attackers sensitive information about the kernel layout
> in memory.
>
> We can reduce the attack surface by hashing all addresses printed with
> %p. This will of course break some users, forcing code printing needed
> addresses to be updated.
>
> With this version we include hashing of malformed specifiers also.
> Malformed specifiers include incomplete (e.g %pi) and also non-existent
> specifiers. checkpatch should warn for non-existent specifiers but
> AFAICT won't warn for incomplete specifiers.
>
> Here is the behaviour that this set implements.
>
> For kpt_restrict==0
>
> Randomness not ready:
> printed with %p: (pointer) # NOTE: with padding
> Valid pointer:
> printed with %pK: deadbeefdeadbeef
> printed with %p: 0xdeadbeef
> malformed specifier (eg %i): 0xdeadbeef
> NULL pointer:
> printed with %pK: 0000000000000000
> printed with %p: (null) # NOTE: no padding
> malformed specifier (eg %i): (null)
a quick question:
do we care about cases when kernel pointers are printed with %x/%X and
not with %p?
-ss
next prev parent reply other threads:[~2017-10-27 13:33 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-26 2:53 [PATCH V8 0/2] printk: hash addresses printed with %p Tobin C. Harding
2017-10-26 2:53 ` [PATCH V8 1/2] printk: remove tabular output for NULL pointer Tobin C. Harding
2017-10-26 4:57 ` Joe Perches
2017-10-26 6:27 ` Tobin C. Harding
2017-10-26 8:05 ` Joe Perches
2017-10-26 9:37 ` Tobin C. Harding
2017-10-26 14:47 ` Joe Perches
2017-10-26 23:57 ` Tobin C. Harding
2017-10-27 0:11 ` Joe Perches
2017-10-26 2:53 ` [PATCH V8 2/2] printk: hash addresses printed with %p Tobin C. Harding
2017-10-26 2:58 ` Tobin C. Harding
2017-10-30 21:33 ` Steven Rostedt
2017-10-30 22:41 ` Tobin C. Harding
2017-10-31 0:00 ` Steven Rostedt
2017-10-31 2:00 ` Tobin C. Harding
2017-10-26 3:11 ` Jason A. Donenfeld
2017-10-27 13:33 ` Sergey Senozhatsky [this message]
2017-10-31 23:35 ` [PATCH V8 0/2] " Tobin C. Harding
2017-11-02 8:23 ` Sergey Senozhatsky
2017-11-02 10:14 ` Tobin C. Harding
2017-11-02 13:43 ` Roberts, William C
2017-11-02 16:04 ` Sergey Senozhatsky
2017-10-30 22:03 ` Kees Cook
2017-10-30 22:33 ` Tobin C. Harding
2017-10-31 2:08 ` Joe Perches
2017-10-31 23:16 ` Tobin C. Harding
2017-10-31 23:33 ` Joe Perches
2017-11-03 5:13 ` Vinod Koul
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