Date: Mon, 13 Nov 2017 17:08:07 +1100 From: "Tobin C. Harding" <me@...in.cc> To: kaiwan.billimoria@...il.com 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 Mon, Nov 13, 2017 at 11:16:28AM +0530, kaiwan.billimoria@...il.com wrote: > On Mon, 2017-11-13 at 09:21 +1100, Tobin C. Harding wrote: > > On Fri, Nov 10, 2017 at 07:26:34PM +0530, kaiwan.billimoria@...il.com > > wrote: > > > On Tue, 2017-11-07 at 21:32 +1100, Tobin C. Harding wrote: > > > > 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. On 32 kernels we don't have this luxury. > > > > > > Tobin C. Harding <me@...in.cc> wrote: > > > > 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. On 32 kernels we don't have this luxury. > > > > > > [RFC] leaking_addresses.pl - enhance it to work for 32-bit kernels > > > as well > > > > > > (Firstly, apologies if I've got the protocol horribly wrong- should > > > this > > > be a new thread altogether?) > > > > I think this patch will need to wait until the patch set that is > > currently in flight is either merged or dropped. > > > Thanks for looking at it! > Okay; blocking on merge || drop... :-) So, Linus has requested that I set up a tree for the development of this. I have to work out the details of how to do that and then I'll email you so you can get the pull the current version. I can then take your patch via LKML as per usual. > > We can work this out pragmatically, Perl can give us an architecture > > string then a few regexs can ascertain which architecture we are > > running > > on. This is in the inflight patch set. > > > > > The patch below does Not take into account (yet) stuff like: > > > - exactly which files & dirs should be skipped on 32-bit (will it > > > be > > > identical to 64-bit?; unsure..) > > > > As per discussion later in this thread we may need to consider > > architecture specific lists for files/directories to skip. > Right > > > > > - it currently hard-codes a global 'PAGE_OFFSET_32BIT=0xc0000000' > > > , just > > > so I can test quickly; must figure whether to query it or pass it; > > > Suggestions? > > > > Perhaps we should have a command line option for this. > > > > --kernel-base-address > > Why not just detect it programatically? We could devise a series of > fallbacks; something like: > - if .config exists in the kernel source tree root, grep it for > PAGE_OFFSET > - if not, grep the arch-specific (arch/<arch>/configs/<config-file>) > for the same > - if for some reason we don't have enough info regarding specific > platform and thus the defconfig filename (could happen for ARM, PPC?), > we then fail and request the user to pass it as a parameter. > > > > - the 'false positives'; again, what differs for 32-bit? Sounds good to me. thanks, Tobin.
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