Date: Tue, 17 Oct 2017 09:31:19 -0400 From: Steven Rostedt <rostedt@...dmis.org> To: "Tobin C. Harding" <me@...in.cc> Cc: kernel-hardening@...ts.openwall.com, Linus Torvalds <torvalds@...ux-foundation.org>, Kees Cook <keescook@...omium.org>, Paolo Bonzini <pbonzini@...hat.com>, Tycho Andersen <tycho@...ker.com>, "Roberts, William C" <william.c.roberts@...el.com>, Tejun Heo <tj@...nel.org>, Jordan Glover <Golden_Miller83@...tonmail.ch>, Greg KH <gregkh@...uxfoundation.org>, Petr Mladek <pmladek@...e.com>, Joe Perches <joe@...ches.com>, Ian Campbell <ijc@...lion.org.uk>, Sergey Senozhatsky <sergey.senozhatsky@...il.com>, Catalin Marinas <catalin.marinas@....com>, Will Deacon <will.deacon@....com>, Chris Fries <cfries@...gle.com>, Dave Weinstein <olorin@...gle.com>, Daniel Micay <danielmicay@...il.com>, Djalal Harouni <tixxdz@...il.com>, linux-kernel@...r.kernel.org Subject: Re: [PATCH v2] printk: hash addresses printed with %p On Tue, 17 Oct 2017 15:52:51 +1100 "Tobin C. Harding" <me@...in.cc> 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. > > For what it's worth, usage of unadorned %p can be broken down as follows > > git grep '%p[^KFfSsBRrbMmIiEUVKNhdDgCGO]' | wc -l Does %p[FfSs] leak addresses? Well, I guess it does if they are not found in kallsyms, but otherwise you have: function+0x<offset> -- Steve > > arch: 2512 > block: 20 > crypto: 12 > fs: 1221 > include: 147 > kernel: 109 > lib: 77 > mm: 120 > net: 1516 > security: 11 > sound: 168 > virt: 2 > drivers: 8420 > > Add helper function siphash_1ulong(). Add function ptr_to_id() to map an > address to a 32 bit unique identifier. > > Signed-off-by: Tobin C. Harding <me@...in.cc> > --- >
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.