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Message-ID: <20171108211608.GC27823@eros> Date: Thu, 9 Nov 2017 08:16:08 +1100 From: "Tobin C. Harding" <me@...in.cc> To: Michael Ellerman <mpe@...erman.id.au> Cc: kernel-hardening@...ts.openwall.com, "Jason A. Donenfeld" <Jason@...c4.com>, Theodore Ts'o <tytso@....edu>, 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 <wilal.deacon@....com>, Steven Rostedt <rostedt@...dmis.org>, 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, Network Development <netdev@...r.kernel.org>, David Miller <davem@...emloft.net> Subject: Re: [PATCH v4] scripts: add leaking_addresses.pl On Wed, Nov 08, 2017 at 11:10:56PM +1100, Michael Ellerman wrote: > "Tobin C. Harding" <me@...in.cc> writes: > > Currently we are leaking addresses from the kernel to user space. This > > script is an attempt to find some of those leakages. Script parses > > `dmesg` output and /proc and /sys files for hex strings that look like > > kernel addresses. > > > > Only works for 64 bit kernels, the reason being that kernel addresses > > on 64 bit kernels have 'ffff' as the leading bit pattern making greping > > possible. > > That doesn't work super well on other architectures :D > > I don't speak perl but presumably you can check the arch somehow and > customise the regex? I'm on it. > ... > > +# Return _all_ non false positive addresses from $line. > > +sub extract_addresses > > +{ > > + my ($line) = @_; > > + my $address = '\b(0x)?ffff[[:xdigit:]]{12}\b'; > > On 64-bit powerpc (ppc64/ppc64le) we'd want: > > + my $address = '\b(0x)?[89abcdef]00[[:xdigit:]]{13}\b'; This is great! Thanks a million. This gives me the idea of getting in contact with people who have access to other [64 bit] architectures and getting the address format. I guess a dump of kallsyms from each architecture would do the job nicely. > > +# Do not parse these files (absolute path). > > +my @skip_parse_files_abs = ('/proc/kmsg', > > + '/proc/kcore', > > + '/proc/fs/ext4/sdb1/mb_groups', > > + '/proc/1/fd/3', > > + '/sys/kernel/debug/tracing/trace_pipe', > > + '/sys/kernel/security/apparmor/revision'); > > Can you add: > > /sys/firmware/devicetree > > and/or /proc/device-tree (which is a symlink to the above). Can do, thanks. > We should also start restricting access to that because it may have > potentially interesting physical addresses in it, but that will break > existing tools, so it will need to be opt-in and done over time. Seems like this is going to be a recurring theme if we try to stop leaks using file permissions. I'm interested in how we would do this, assuming it has to be a case by case fix but done many times. thanks, Tobin.
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