From: Kees Cook <keescook@chromium.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org,
linux-s390@vger.kernel.org, linux-c6x-dev@linux-c6x.org,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Michal Simek <monstr@monstr.eu>,
linux-parisc@vger.kernel.org, linux-xtensa@linux-xtensa.org,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 07/29] x86: Restore "text" Program Header with dummy section
Date: Thu, 10 Oct 2019 09:46:36 -0700 [thread overview]
Message-ID: <201910100944.92CFB97157@keescook> (raw)
In-Reply-To: <20191010103305.GD7658@zn.tnic>
On Thu, Oct 10, 2019 at 12:33:05PM +0200, Borislav Petkov wrote:
> On Thu, Sep 26, 2019 at 10:55:40AM -0700, Kees Cook wrote:
> > Instead of depending on markings in the section following NOTES to
> > restore the associated Program Header, use a dummy section, as done
> > in other architectures.
>
> This is very laconic and after some staring at ld.info, I think you mean
> this:
>
> " If you place a section in one or more segments using ':PHDR', then
> the linker will place all subsequent allocatable sections which do not
> specify ':PHDR' in the same segments."
>
> but I could be way off. Yes, no?
>
> IOW, please write in the commit messages first what the problem is
> you're addressing.
Yeah, that's much improved. I really struggled to describe this, given
how weird the linker script logic is here.
> > --- a/arch/x86/kernel/vmlinux.lds.S
> > +++ b/arch/x86/kernel/vmlinux.lds.S
> > @@ -147,8 +147,9 @@ SECTIONS
> > } :text = 0x9090
> >
> > NOTES :text :note
> > + .dummy : { *(.dummy) } :text
> >
> > - EXCEPTION_TABLE(16) :text = 0x9090
> > + EXCEPTION_TABLE(16)
>
> This is killing the filler byte but I have a suspicion that'll change
> eventually to INT3... :)
Yes, though since the exception table isn't executable, filling with
0x90 has no meaning, and I think when I looked at the alignment there
were actually no fill bytes from here on. But it doesn't matter; it all
goes away in the end.
--
Kees Cook
WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org,
linux-s390@vger.kernel.org, linux-c6x-dev@linux-c6x.org,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Michal Simek <monstr@monstr.eu>,
linux-parisc@vger.kernel.org, linux-xtensa@linux-xtensa.org,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 07/29] x86: Restore "text" Program Header with dummy section
Date: Thu, 10 Oct 2019 16:46:36 +0000 [thread overview]
Message-ID: <201910100944.92CFB97157@keescook> (raw)
In-Reply-To: <20191010103305.GD7658@zn.tnic>
On Thu, Oct 10, 2019 at 12:33:05PM +0200, Borislav Petkov wrote:
> On Thu, Sep 26, 2019 at 10:55:40AM -0700, Kees Cook wrote:
> > Instead of depending on markings in the section following NOTES to
> > restore the associated Program Header, use a dummy section, as done
> > in other architectures.
>
> This is very laconic and after some staring at ld.info, I think you mean
> this:
>
> " If you place a section in one or more segments using ':PHDR', then
> the linker will place all subsequent allocatable sections which do not
> specify ':PHDR' in the same segments."
>
> but I could be way off. Yes, no?
>
> IOW, please write in the commit messages first what the problem is
> you're addressing.
Yeah, that's much improved. I really struggled to describe this, given
how weird the linker script logic is here.
> > --- a/arch/x86/kernel/vmlinux.lds.S
> > +++ b/arch/x86/kernel/vmlinux.lds.S
> > @@ -147,8 +147,9 @@ SECTIONS
> > } :text = 0x9090
> >
> > NOTES :text :note
> > + .dummy : { *(.dummy) } :text
> >
> > - EXCEPTION_TABLE(16) :text = 0x9090
> > + EXCEPTION_TABLE(16)
>
> This is killing the filler byte but I have a suspicion that'll change
> eventually to INT3... :)
Yes, though since the exception table isn't executable, filling with
0x90 has no meaning, and I think when I looked at the alignment there
were actually no fill bytes from here on. But it doesn't matter; it all
goes away in the end.
--
Kees Cook
WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org>
To: Borislav Petkov <bp@alien8.de>
Cc: linux-arch@vger.kernel.org, linux-s390@vger.kernel.org,
Michal Simek <monstr@monstr.eu>,
linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org,
linux-c6x-dev@linux-c6x.org, Arnd Bergmann <arnd@arndb.de>,
linux-xtensa@linux-xtensa.org, linux-kernel@vger.kernel.org,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, Yoshinori Sato <ysato@users.sourceforge.jp>,
Ingo Molnar <mingo@redhat.com>,
linux-parisc@vger.kernel.org, Andy Lutomirski <luto@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 07/29] x86: Restore "text" Program Header with dummy section
Date: Thu, 10 Oct 2019 09:46:36 -0700 [thread overview]
Message-ID: <201910100944.92CFB97157@keescook> (raw)
In-Reply-To: <20191010103305.GD7658@zn.tnic>
On Thu, Oct 10, 2019 at 12:33:05PM +0200, Borislav Petkov wrote:
> On Thu, Sep 26, 2019 at 10:55:40AM -0700, Kees Cook wrote:
> > Instead of depending on markings in the section following NOTES to
> > restore the associated Program Header, use a dummy section, as done
> > in other architectures.
>
> This is very laconic and after some staring at ld.info, I think you mean
> this:
>
> " If you place a section in one or more segments using ':PHDR', then
> the linker will place all subsequent allocatable sections which do not
> specify ':PHDR' in the same segments."
>
> but I could be way off. Yes, no?
>
> IOW, please write in the commit messages first what the problem is
> you're addressing.
Yeah, that's much improved. I really struggled to describe this, given
how weird the linker script logic is here.
> > --- a/arch/x86/kernel/vmlinux.lds.S
> > +++ b/arch/x86/kernel/vmlinux.lds.S
> > @@ -147,8 +147,9 @@ SECTIONS
> > } :text = 0x9090
> >
> > NOTES :text :note
> > + .dummy : { *(.dummy) } :text
> >
> > - EXCEPTION_TABLE(16) :text = 0x9090
> > + EXCEPTION_TABLE(16)
>
> This is killing the filler byte but I have a suspicion that'll change
> eventually to INT3... :)
Yes, though since the exception table isn't executable, filling with
0x90 has no meaning, and I think when I looked at the alignment there
were actually no fill bytes from here on. But it doesn't matter; it all
goes away in the end.
--
Kees Cook
next prev parent reply other threads:[~2019-10-10 16:46 UTC|newest]
Thread overview: 126+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-26 17:55 [PATCH 00/29] vmlinux.lds.h: Refactor EXCEPTION_TABLE and NOTES Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 01/29] powerpc: Rename "notes" PT_NOTE to "note" Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 02/29] powerpc: Remove PT_NOTE workaround Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 03/29] powerpc: Rename PT_LOAD identifier "kernel" to "text" Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 04/29] alpha: " Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 05/29] ia64: Rename PT_LOAD identifier "code" " Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 06/29] s390: Move RO_DATA into "text" PT_LOAD Program Header Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 07/29] x86: Restore "text" Program Header with dummy section Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-10-10 10:33 ` Borislav Petkov
2019-10-10 10:33 ` Borislav Petkov
2019-10-10 10:33 ` Borislav Petkov
2019-10-10 16:46 ` Kees Cook [this message]
2019-10-10 16:46 ` Kees Cook
2019-10-10 16:46 ` Kees Cook
2019-09-26 17:55 ` [PATCH 08/29] vmlinux.lds.h: Provide EMIT_PT_NOTE to indicate export of .notes Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-10-10 10:40 ` Borislav Petkov
2019-10-10 10:40 ` Borislav Petkov
2019-10-10 10:40 ` Borislav Petkov
2019-09-26 17:55 ` [PATCH 09/29] vmlinux.lds.h: Move Program Header restoration into NOTES macro Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 10/29] vmlinux.lds.h: Move NOTES into RO_DATA Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 11/29] vmlinux.lds.h: Replace RODATA with RO_DATA Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 12/29] vmlinux.lds.h: Replace RO_DATA_SECTION " Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 13/29] vmlinux.lds.h: Replace RW_DATA_SECTION with RW_DATA Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 14/29] vmlinux.lds.h: Allow EXCEPTION_TABLE to live in RO_DATA Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-10-01 9:05 ` Will Deacon
2019-10-01 9:05 ` Will Deacon
2019-10-01 9:05 ` Will Deacon
2019-10-10 15:25 ` Borislav Petkov
2019-10-10 15:25 ` Borislav Petkov
2019-10-10 15:25 ` Borislav Petkov
2019-10-10 16:47 ` Kees Cook
2019-10-10 16:47 ` Kees Cook
2019-10-10 16:47 ` Kees Cook
2019-09-26 17:55 ` [PATCH 15/29] x86: Actually use _etext for end of text segment Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 16/29] x86: Move EXCEPTION_TABLE to RO_DATA segment Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 17/29] alpha: " Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 18/29] arm64: " Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-10-01 9:03 ` Will Deacon
2019-10-01 9:03 ` Will Deacon
2019-10-01 9:03 ` Will Deacon
2019-10-01 15:48 ` Kees Cook
2019-10-01 15:48 ` Kees Cook
2019-10-01 15:48 ` Kees Cook
2019-09-26 17:55 ` [PATCH 19/29] c6x: " Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 20/29] h8300: " Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 21/29] ia64: " Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 22/29] microblaze: " Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 23/29] parisc: " Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 24/29] powerpc: " Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 25/29] xtensa: " Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` [PATCH 26/29] x86/mm: Remove redundant &s on addresses Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:55 ` Kees Cook
2019-09-26 17:56 ` [PATCH 27/29] x86/mm: Report which part of kernel image is freed Kees Cook
2019-09-26 17:56 ` Kees Cook
2019-09-26 17:56 ` Kees Cook
2019-09-26 17:56 ` [PATCH 28/29] x86/mm: Report actual image regions in /proc/iomem Kees Cook
2019-09-26 17:56 ` Kees Cook
2019-09-26 17:56 ` Kees Cook
2019-10-10 18:00 ` Borislav Petkov
2019-10-10 18:00 ` Borislav Petkov
2019-10-10 18:00 ` Borislav Petkov
2019-09-26 17:56 ` [PATCH 29/29] x86: Use INT3 instead of NOP for linker fill bytes Kees Cook
2019-09-26 17:56 ` Kees Cook
2019-09-26 17:56 ` Kees Cook
2019-10-10 18:03 ` [PATCH 00/29] vmlinux.lds.h: Refactor EXCEPTION_TABLE and NOTES Borislav Petkov
2019-10-10 18:03 ` Borislav Petkov
2019-10-10 18:03 ` Borislav Petkov
2019-10-10 23:57 ` Kees Cook
2019-10-10 23:57 ` Kees Cook
2019-10-10 23:57 ` Kees Cook
2019-10-11 1:38 ` hpa
2019-10-11 1:38 ` hpa
2019-10-11 1:38 ` hpa
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