All of lore.kernel.org
 help / color / mirror / Atom feed
From: Arvind Sankar <nivedita@alum.mit.edu>
To: Kees Cook <keescook@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Peter Collingbourne <pcc@google.com>,
	James Morse <james.morse@arm.com>, Borislav Petkov <bp@suse.de>,
	Ingo Molnar <mingo@redhat.com>,
	Russell King <linux@armlinux.org.uk>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Arvind Sankar <nivedita@alum.mit.edu>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Nathan Chancellor <natechancellor@gmail.com>,
	Arnd Bergmann <arnd@arndb.de>,
	x86@kernel.org, clang-built-linux@googlegroups.com,
	linux-arch@vger.kernel.org, linux-efi@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 29/36] x86/build: Enforce an empty .got.plt section
Date: Fri, 31 Jul 2020 22:12:48 -0400	[thread overview]
Message-ID: <20200801021248.GB2700342@rani.riverdale.lan> (raw)
In-Reply-To: <20200731230820.1742553-30-keescook@chromium.org>

On Fri, Jul 31, 2020 at 04:08:13PM -0700, Kees Cook wrote:
> The .got.plt section should always be zero (or filled only with the
> linker-generated lazy dispatch entry). Enforce this with an assert and
> mark the section as NOLOAD. This is more sensitive than just blindly
> discarding the section.
> 
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  arch/x86/kernel/vmlinux.lds.S | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
> index 0cc035cb15f1..7faffe7414d6 100644
> --- a/arch/x86/kernel/vmlinux.lds.S
> +++ b/arch/x86/kernel/vmlinux.lds.S
> @@ -414,8 +414,20 @@ SECTIONS
>  	ELF_DETAILS
>  
>  	DISCARDS
> -}
>  
> +	/*
> +	 * Make sure that the .got.plt is either completely empty or it
> +	 * contains only the lazy dispatch entries.
> +	 */
> +	.got.plt (NOLOAD) : { *(.got.plt) }
> +	ASSERT(SIZEOF(.got.plt) == 0 ||
> +#ifdef CONFIG_X86_64
> +	       SIZEOF(.got.plt) == 0x18,
> +#else
> +	       SIZEOF(.got.plt) == 0xc,
> +#endif
> +	       "Unexpected GOT/PLT entries detected!")
> +}
>  
>  #ifdef CONFIG_X86_32
>  /*
> -- 
> 2.25.1
> 

Is this actually needed? vmlinux is a position-dependent executable, and
it doesn't get linked with any shared libraries, so it should never have
a .got or .got.plt at all I think? Does it show up as an orphan without
this?

WARNING: multiple messages have this Message-ID (diff)
From: Arvind Sankar <nivedita@alum.mit.edu>
To: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	linux-arch@vger.kernel.org, linux-efi@vger.kernel.org,
	Arnd Bergmann <arnd@arndb.de>,
	Peter Collingbourne <pcc@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	x86@kernel.org, Nick Desaulniers <ndesaulniers@google.com>,
	Russell King <linux@armlinux.org.uk>,
	linux-kernel@vger.kernel.org,
	Nathan Chancellor <natechancellor@gmail.com>,
	clang-built-linux@googlegroups.com,
	Arvind Sankar <nivedita@alum.mit.edu>,
	Ingo Molnar <mingo@redhat.com>, James Morse <james.morse@arm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@suse.de>, Will Deacon <will@kernel.org>,
	Ard Biesheuvel <ardb@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v5 29/36] x86/build: Enforce an empty .got.plt section
Date: Fri, 31 Jul 2020 22:12:48 -0400	[thread overview]
Message-ID: <20200801021248.GB2700342@rani.riverdale.lan> (raw)
In-Reply-To: <20200731230820.1742553-30-keescook@chromium.org>

On Fri, Jul 31, 2020 at 04:08:13PM -0700, Kees Cook wrote:
> The .got.plt section should always be zero (or filled only with the
> linker-generated lazy dispatch entry). Enforce this with an assert and
> mark the section as NOLOAD. This is more sensitive than just blindly
> discarding the section.
> 
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  arch/x86/kernel/vmlinux.lds.S | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
> index 0cc035cb15f1..7faffe7414d6 100644
> --- a/arch/x86/kernel/vmlinux.lds.S
> +++ b/arch/x86/kernel/vmlinux.lds.S
> @@ -414,8 +414,20 @@ SECTIONS
>  	ELF_DETAILS
>  
>  	DISCARDS
> -}
>  
> +	/*
> +	 * Make sure that the .got.plt is either completely empty or it
> +	 * contains only the lazy dispatch entries.
> +	 */
> +	.got.plt (NOLOAD) : { *(.got.plt) }
> +	ASSERT(SIZEOF(.got.plt) == 0 ||
> +#ifdef CONFIG_X86_64
> +	       SIZEOF(.got.plt) == 0x18,
> +#else
> +	       SIZEOF(.got.plt) == 0xc,
> +#endif
> +	       "Unexpected GOT/PLT entries detected!")
> +}
>  
>  #ifdef CONFIG_X86_32
>  /*
> -- 
> 2.25.1
> 

Is this actually needed? vmlinux is a position-dependent executable, and
it doesn't get linked with any shared libraries, so it should never have
a .got or .got.plt at all I think? Does it show up as an orphan without
this?

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2020-08-01  2:12 UTC|newest]

Thread overview: 152+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-31 23:07 [PATCH v5 00/36] Warn on orphan section placement Kees Cook
2020-07-31 23:07 ` Kees Cook
2020-07-31 23:07 ` [PATCH v5 01/36] x86/boot/compressed: Move .got.plt entries out of the .got section Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-08-14 15:23   ` [tip: x86/boot] " tip-bot2 for Ard Biesheuvel
2020-07-31 23:07 ` [PATCH v5 02/36] x86/boot/compressed: Force hidden visibility for all symbol references Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-08-14 15:23   ` [tip: x86/boot] " tip-bot2 for Ard Biesheuvel
2020-07-31 23:07 ` [PATCH v5 03/36] x86/boot/compressed: Get rid of GOT fixup code Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-08-14 15:23   ` [tip: x86/boot] " tip-bot2 for Ard Biesheuvel
2020-07-31 23:07 ` [PATCH v5 04/36] x86/boot: Add .text.* to setup.ld Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-08-14 15:23   ` [tip: x86/boot] " tip-bot2 for Arvind Sankar
2020-07-31 23:07 ` [PATCH v5 05/36] x86/boot: Remove run-time relocations from .head.text code Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-07-31 23:42   ` Nick Desaulniers
2020-07-31 23:42     ` Nick Desaulniers
2020-07-31 23:42     ` Nick Desaulniers
2020-08-14 15:23   ` [tip: x86/boot] " tip-bot2 for Arvind Sankar
2020-07-31 23:07 ` [PATCH v5 06/36] x86/boot: Remove run-time relocations from head_{32,64}.S Kees Cook
2020-07-31 23:07   ` [PATCH v5 06/36] x86/boot: Remove run-time relocations from head_{32, 64}.S Kees Cook
2020-07-31 23:07   ` [PATCH v5 06/36] x86/boot: Remove run-time relocations from head_{32,64}.S Kees Cook
2020-08-07 18:12   ` Nick Desaulniers
2020-08-07 18:12     ` [PATCH v5 06/36] x86/boot: Remove run-time relocations from head_{32, 64}.S Nick Desaulniers
2020-08-07 20:20     ` [PATCH v5 06/36] x86/boot: Remove run-time relocations from head_{32,64}.S Arvind Sankar
2020-08-07 20:20       ` Arvind Sankar
2020-08-14 15:23   ` [tip: x86/boot] " tip-bot2 for Arvind Sankar
2020-07-31 23:07 ` [PATCH v5 07/36] x86/boot: Check that there are no run-time relocations Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-08-14 15:23   ` [tip: x86/boot] " tip-bot2 for Arvind Sankar
2020-07-31 23:07 ` [PATCH v5 08/36] vmlinux.lds.h: Create COMMON_DISCARDS Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-07-31 23:07 ` [PATCH v5 09/36] vmlinux.lds.h: Add .gnu.version* to COMMON_DISCARDS Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-07-31 23:07 ` [PATCH v5 10/36] vmlinux.lds.h: Avoid KASAN and KCSAN's unwanted sections Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-07-31 23:07 ` [PATCH v5 11/36] vmlinux.lds.h: Split ELF_DETAILS from STABS_DEBUG Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-07-31 23:07 ` [PATCH v5 12/36] vmlinux.lds.h: Add .symtab, .strtab, and .shstrtab to ELF_DETAILS Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-07-31 23:07 ` [PATCH v5 13/36] vmlinux.lds.h: add PGO and AutoFDO input sections Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-08-01  3:51   ` Arvind Sankar
2020-08-01  3:51     ` Arvind Sankar
2020-08-01  3:51     ` Arvind Sankar
2020-08-01  6:18     ` Kees Cook
2020-08-01  6:18       ` Kees Cook
2020-08-01  6:18       ` Kees Cook
2020-08-01 17:27       ` Arvind Sankar
2020-08-01 17:27         ` Arvind Sankar
2020-08-01 17:27         ` Arvind Sankar
2020-08-03 19:05     ` Andi Kleen
2020-08-03 19:05       ` Andi Kleen
2020-08-03 19:05       ` Andi Kleen
2020-08-03 20:15       ` Arvind Sankar
2020-08-03 20:15         ` Arvind Sankar
2020-08-03 20:15         ` Arvind Sankar
2020-08-04  1:19         ` Fāng-ruì Sòng
2020-08-04  1:19           ` Fāng-ruì Sòng
2020-08-04  1:19           ` Fāng-ruì Sòng
2020-08-04  4:45         ` Andi Kleen
2020-08-04  4:45           ` Andi Kleen
2020-08-04  4:45           ` Andi Kleen
2020-08-04  5:32           ` Fāng-ruì Sòng
2020-08-04  5:32             ` Fāng-ruì Sòng
2020-08-04  5:32             ` Fāng-ruì Sòng
2020-08-04 16:06           ` Arvind Sankar
2020-08-04 16:06             ` Arvind Sankar
2020-08-04 16:06             ` Arvind Sankar
2020-08-21 19:18             ` Kees Cook
2020-08-21 19:18               ` Kees Cook
2020-08-06  1:24   ` Sasha Levin
2020-08-06  1:28     ` Nick Desaulniers
2020-08-19 23:56   ` Sasha Levin
2020-07-31 23:07 ` [PATCH v5 14/36] efi/libstub: Disable -mbranch-protection Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-07-31 23:07 ` [PATCH v5 15/36] arm64/mm: Remove needless section quotes Kees Cook
2020-07-31 23:07   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 16/36] arm64/kernel: Remove needless Call Frame Information annotations Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 17/36] arm64/build: Remove .eh_frame* sections due to unwind tables Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 18/36] arm64/build: Use common DISCARDS in linker script Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 19/36] arm64/build: Add missing DWARF sections Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 20/36] arm64/build: Assert for unwanted sections Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 21/36] arm64/build: Warn on orphan section placement Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 22/36] arm/build: Refactor linker script headers Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 23/36] arm/build: Explicitly keep .ARM.attributes sections Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-08-03 19:02   ` Nick Desaulniers
2020-08-03 19:02     ` Nick Desaulniers
2020-08-03 19:02     ` Nick Desaulniers
2020-08-17 22:06     ` Fangrui Song
2020-08-17 22:06       ` Fangrui Song
2020-07-31 23:08 ` [PATCH v5 24/36] arm/build: Add missing sections Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 25/36] arm/build: Warn on orphan section placement Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 26/36] arm/boot: Handle all sections explicitly Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 27/36] arm/boot: Warn on orphan section placement Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 28/36] x86/asm: Avoid generating unused kprobe sections Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 29/36] x86/build: Enforce an empty .got.plt section Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-08-01  2:12   ` Arvind Sankar [this message]
2020-08-01  2:12     ` Arvind Sankar
2020-08-01  5:32     ` Kees Cook
2020-08-01  5:32       ` Kees Cook
2020-08-21 17:49     ` Kees Cook
2020-08-21 17:49       ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 30/36] x86/build: Assert for unwanted sections Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 31/36] x86/build: Warn on orphan section placement Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 32/36] x86/boot/compressed: Reorganize zero-size section asserts Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-08-01  1:47   ` Arvind Sankar
2020-08-01  1:47     ` Arvind Sankar
2020-08-01  2:53     ` Arvind Sankar
2020-08-01  2:53       ` Arvind Sankar
2020-08-01  5:36       ` Kees Cook
2020-08-01  5:36         ` Kees Cook
2020-08-01 17:12         ` Arvind Sankar
2020-08-01 17:12           ` Arvind Sankar
2020-08-21 18:24           ` Kees Cook
2020-08-21 18:24             ` Kees Cook
2020-08-01  5:35     ` Kees Cook
2020-08-01  5:35       ` Kees Cook
2020-08-01 17:00       ` Arvind Sankar
2020-08-01 17:00         ` Arvind Sankar
2020-08-21 18:19     ` Kees Cook
2020-08-21 18:19       ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 33/36] x86/boot/compressed: Remove, discard, or assert for unwanted sections Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 34/36] x86/boot/compressed: Add missing debugging sections to output Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 35/36] x86/boot/compressed: Warn on orphan section placement Kees Cook
2020-07-31 23:08   ` Kees Cook
2020-07-31 23:08 ` [PATCH v5 36/36] arm/build: Assert for unwanted sections Kees Cook
2020-07-31 23:08   ` Kees Cook

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200801021248.GB2700342@rani.riverdale.lan \
    --to=nivedita@alum.mit.edu \
    --cc=ardb@kernel.org \
    --cc=arnd@arndb.de \
    --cc=bp@suse.de \
    --cc=catalin.marinas@arm.com \
    --cc=clang-built-linux@googlegroups.com \
    --cc=james.morse@arm.com \
    --cc=keescook@chromium.org \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-efi@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@armlinux.org.uk \
    --cc=mark.rutland@arm.com \
    --cc=masahiroy@kernel.org \
    --cc=mingo@redhat.com \
    --cc=natechancellor@gmail.com \
    --cc=ndesaulniers@google.com \
    --cc=pcc@google.com \
    --cc=tglx@linutronix.de \
    --cc=will@kernel.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.