On Mon, Nov 13, 2017 at 11:16:28AM +0530, kaiwan.billimo...@gmail.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.billimo...@gmail.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 <m...@tobin.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.
