Messages in this thread | | | Date | Wed, 10 Sep 2014 14:10:35 +0800 | From | Baoquan He <> | Subject | Re: [PATCH 1/4] kaslr: check user's config too when handle relocations |
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On 09/09/14 at 08:53am, Kees Cook wrote: > > > Hi Kees, > > > > Checking handle_relocations() again, I just didn't notice it's mandatory > > to do the relocations handling in i386. So in this function delta is > > checked to see if it's a kaslr relocation handling. This might be a > > little confusing. But I am fine with it. > > > > Per your comment, you prefer to compare the output before and after > > choose_kernel_location(). That's also good, Lu Yinghai posted a draft > > patch in this way before, however the checking and the delta calculation > > are not correct. I changed that and test all cases, it works well. So > > do you like this it? If yes I will repost it. > > > > From 13471bd838c52a0e143c2aee81e3863cfff585bd Mon Sep 17 00:00:00 2001 > > From: Baoquan He <bhe@redhat.com> > > Date: Mon, 25 Aug 2014 14:57:43 +0800 > > Subject: [PATCH] kaslr: check if kernel location is changed > > > > Signed-off-by: Baoquan He <bhe@redhat.com> > > --- > > arch/x86/boot/compressed/misc.c | 15 +++++++++++---- > > 1 file changed, 11 insertions(+), 4 deletions(-) > > > > diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c > > index 57ab74d..887f404 100644 > > --- a/arch/x86/boot/compressed/misc.c > > +++ b/arch/x86/boot/compressed/misc.c > > @@ -230,8 +230,9 @@ static void error(char *x) > > asm("hlt"); > > } > > > > -#if CONFIG_X86_NEED_RELOCS > > -static void handle_relocations(void *output, unsigned long output_len) > > +#ifdef CONFIG_X86_NEED_RELOCS > > +static void handle_relocations(void *output_orig, void *output, > > + unsigned long output_len) > > { > > int *reloc; > > unsigned long delta, map, ptr; > > @@ -242,6 +243,9 @@ static void handle_relocations(void *output, unsigned long output_len) > > * Calculate the delta between where vmlinux was linked to load > > * and where it was actually loaded. > > */ > > + if (output_orig == output) > > + return; > > + > > I still think this needs a test for the 32-bit case, since IUIC, it > requires relocations unconditionally.
Oops, just understood that 32 bit kernel alwasy need relocations, but only focus on x86_64 and kaslr again when I was doing it. You are right, this is not correct for 32 bit kernel.
I am thinking if I can add a compiling condition check like below. This only works only when x86_64 or when kaslr is compiled in. Otherwise it wokrs as before.
#if CONFIG_X86_64 if (output_orig == output) return; #endif
or #if CONFIG_RANDOMIZE_BASE if (output_orig == output) return; #endif
> > -Kees >
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