From: Kees Cook <keescook@chromium.org>
To: Yinghai Lu <yinghai@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Baoquan He <bhe@redhat.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 02/42] x86, boot: Move compressed kernel to end of buffer before decompressing
Date: Tue, 7 Jul 2015 14:22:26 -0700 [thread overview]
Message-ID: <CAGXu5jL6gWML6AWGBGpA1GVMa9xBBeCHud5ciEoFYpbqGQzbrA@mail.gmail.com> (raw)
In-Reply-To: <1436300428-21163-3-git-send-email-yinghai@kernel.org>
On Tue, Jul 7, 2015 at 1:19 PM, Yinghai Lu <yinghai@kernel.org> wrote:
> So we can find out ZO position easily during run-time for kasl buffer
> searching.
Can you define VO and ZO for this changelog? I understand "VO" to mean
"uncompressed kernel", and "ZO" to mean "compressed kernel", is that
accurate? Maybe "ZO" should be "compressed kernel blob with
decompression code"? I'm not clear on the elements you're talking
about here.
> Current code is using extract_offset to control copied kernel position, it
> will put the copied kernel in the middle of buffer when kernel run size is
> bigger than decompressed needed buffer size.
Doesn't it unconditionally put the compressed kernel at extract_offset?
> Current layout:
> when init_size is the same as kernel run_size:
> run_size
> 0 extract_offset init_size
> |------------------|------------------------|
> VO text/data VO bss/brk
> input ZO text ZO data
I don't understand this picture. The locations of "VO bss/brk" and
"input ZO text ZO data" don't make sense to me. Are you trying to show
that they are aligned with extract_offset and init_size?
>
> This patch try to:
> move ZO to the end of buffer instead of middle of the buffer.
> When init_size is bigger than kernel run size, will have
>
> 0 run_size init_size
> |--------------------------------|----------|
> VO text/data VO bss/brk
> input ZO text ZO data
Won't run_size always be larger than init_size?
> We already have init_size the buffer size, we can find the end easily
> when copying ZO before decompressing.
Which buffer do you mean?
Another thing I'd like to understand is what problem does this patch
solve? I see that it rearranges things, but why is this useful?
Thanks for working on these!
-Kees
>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> ---
> arch/x86/boot/compressed/head_32.S | 11 +++++++++--
> arch/x86/boot/compressed/head_64.S | 8 ++++++--
> arch/x86/boot/compressed/mkpiggy.c | 7 ++-----
> arch/x86/boot/compressed/vmlinux.lds.S | 1 +
> arch/x86/boot/header.S | 2 +-
> arch/x86/kernel/asm-offsets.c | 1 +
> arch/x86/kernel/vmlinux.lds.S | 1 +
> 7 files changed, 21 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
> index 8ef964d..0c140f9 100644
> --- a/arch/x86/boot/compressed/head_32.S
> +++ b/arch/x86/boot/compressed/head_32.S
> @@ -148,7 +148,9 @@ preferred_addr:
> 1:
>
> /* Target address to relocate to for decompression */
> - addl $z_extract_offset, %ebx
> + movl BP_init_size(%esi), %eax
> + subl $_end, %eax
> + addl %eax, %ebx
>
> /* Set up the stack */
> leal boot_stack_end(%ebx), %esp
> @@ -210,8 +212,13 @@ relocated:
> /* push arguments for decompress_kernel: */
> pushl $z_run_size /* size of kernel with .bss and .brk */
> pushl $z_output_len /* decompressed length, end of relocs */
> - leal z_extract_offset_negative(%ebx), %ebp
> +
> + movl BP_init_size(%esi), %eax
> + subl $_end, %eax
> + movl %ebx, %ebp
> + subl %eax, %ebp
> pushl %ebp /* output address */
> +
> pushl $z_input_len /* input_len */
> leal input_data(%ebx), %eax
> pushl %eax /* input_data */
> diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
> index b0c0d16..67dd8d3 100644
> --- a/arch/x86/boot/compressed/head_64.S
> +++ b/arch/x86/boot/compressed/head_64.S
> @@ -102,7 +102,9 @@ ENTRY(startup_32)
> 1:
>
> /* Target address to relocate to for decompression */
> - addl $z_extract_offset, %ebx
> + movl BP_init_size(%esi), %eax
> + subl $_end, %eax
> + addl %eax, %ebx
>
> /*
> * Prepare for entering 64 bit mode
> @@ -330,7 +332,9 @@ preferred_addr:
> 1:
>
> /* Target address to relocate to for decompression */
> - leaq z_extract_offset(%rbp), %rbx
> + movl BP_init_size(%rsi), %ebx
> + subl $_end, %ebx
> + addq %rbp, %rbx
>
> /* Set up the stack */
> leaq boot_stack_end(%rbx), %rsp
> diff --git a/arch/x86/boot/compressed/mkpiggy.c b/arch/x86/boot/compressed/mkpiggy.c
> index d8222f2..5faad09 100644
> --- a/arch/x86/boot/compressed/mkpiggy.c
> +++ b/arch/x86/boot/compressed/mkpiggy.c
> @@ -83,11 +83,8 @@ int main(int argc, char *argv[])
> printf("z_input_len = %lu\n", ilen);
> printf(".globl z_output_len\n");
> printf("z_output_len = %lu\n", (unsigned long)olen);
> - printf(".globl z_extract_offset\n");
> - printf("z_extract_offset = 0x%lx\n", offs);
> - /* z_extract_offset_negative allows simplification of head_32.S */
> - printf(".globl z_extract_offset_negative\n");
> - printf("z_extract_offset_negative = -0x%lx\n", offs);
> + printf(".globl z_min_extract_offset\n");
> + printf("z_min_extract_offset = 0x%lx\n", offs);
> printf(".globl z_run_size\n");
> printf("z_run_size = %lu\n", run_size);
>
> diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S
> index 34d047c..e24e0a0 100644
> --- a/arch/x86/boot/compressed/vmlinux.lds.S
> +++ b/arch/x86/boot/compressed/vmlinux.lds.S
> @@ -70,5 +70,6 @@ SECTIONS
> _epgtable = . ;
> }
> #endif
> + . = ALIGN(PAGE_SIZE); /* keep ZO size page aligned */
> _end = .;
> }
> diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
> index 16ef025..9bfab22 100644
> --- a/arch/x86/boot/header.S
> +++ b/arch/x86/boot/header.S
> @@ -440,7 +440,7 @@ setup_data: .quad 0 # 64-bit physical pointer to
>
> pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr
>
> -#define ZO_INIT_SIZE (ZO__end - ZO_startup_32 + ZO_z_extract_offset)
> +#define ZO_INIT_SIZE (ZO__end - ZO_startup_32 + ZO_z_min_extract_offset)
> #define VO_INIT_SIZE (VO__end - VO__text)
> #if ZO_INIT_SIZE > VO_INIT_SIZE
> #define INIT_SIZE ZO_INIT_SIZE
> diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
> index 8e3d22a1..d2e00bc 100644
> --- a/arch/x86/kernel/asm-offsets.c
> +++ b/arch/x86/kernel/asm-offsets.c
> @@ -87,6 +87,7 @@ void common(void) {
> OFFSET(BP_hardware_subarch, boot_params, hdr.hardware_subarch);
> OFFSET(BP_version, boot_params, hdr.version);
> OFFSET(BP_kernel_alignment, boot_params, hdr.kernel_alignment);
> + OFFSET(BP_init_size, boot_params, hdr.init_size);
> OFFSET(BP_pref_address, boot_params, hdr.pref_address);
> OFFSET(BP_code32_start, boot_params, hdr.code32_start);
>
> diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
> index 00bf300..5816920 100644
> --- a/arch/x86/kernel/vmlinux.lds.S
> +++ b/arch/x86/kernel/vmlinux.lds.S
> @@ -325,6 +325,7 @@ SECTIONS
> __brk_limit = .;
> }
>
> + . = ALIGN(PAGE_SIZE); /* keep VO_INIT_SIZE page aligned */
> _end = .;
>
> STABS_DEBUG
> --
> 1.8.4.5
>
--
Kees Cook
Chrome OS Security
next prev parent reply other threads:[~2015-07-07 21:22 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-07 20:19 [PATCH 00/42] x86: updated patches for kaslr and setup_data etc for v4.3 Yinghai Lu
2015-07-07 20:19 ` [PATCH 01/42] x86, kasl: Remove not needed parameter for choose_kernel_location Yinghai Lu
2015-07-07 20:57 ` Kees Cook
2015-07-07 20:19 ` [PATCH 02/42] x86, boot: Move compressed kernel to end of buffer before decompressing Yinghai Lu
2015-07-07 21:22 ` Kees Cook [this message]
2015-07-07 20:19 ` [PATCH 03/42] x86, boot: Fix run_size calculation Yinghai Lu
2015-07-07 22:15 ` Kees Cook
2015-07-07 20:19 ` [PATCH 04/42] x86, kaslr: Kill not needed and wrong run_size calculation code Yinghai Lu
2015-07-07 22:18 ` Kees Cook
2015-07-07 20:19 ` [PATCH 05/42] x86, kaslr: rename output_size to output_run_size Yinghai Lu
2015-07-07 20:19 ` [PATCH 06/42] x86, kaslr: Consolidate mem_avoid array filling Yinghai Lu
2015-07-07 22:36 ` Kees Cook
2015-07-07 20:19 ` [PATCH 07/42] x86, boot: Move z_extract_offset calculation to header.S Yinghai Lu
2015-07-07 20:19 ` [PATCH 08/42] x86, kaslr: Get correct max_addr for relocs pointer Yinghai Lu
2015-07-07 22:40 ` Kees Cook
2015-07-07 20:19 ` [PATCH 09/42] x86, boot: Split kernel_ident_mapping_init to another file Yinghai Lu
2015-07-07 20:19 ` [PATCH 10/42] x86, 64bit: Set ident_mapping for kaslr Yinghai Lu
2015-07-07 20:19 ` [PATCH 11/42] x86, boot: Add checking for memcpy Yinghai Lu
2015-07-07 20:19 ` [PATCH 12/42] x86, kaslr: Fix a bug that relocation can not be handled when kernel is loaded above 2G Yinghai Lu
2015-07-07 22:42 ` Kees Cook
2015-07-07 20:19 ` [PATCH 13/42] x86, kaslr: Introduce struct slot_area to manage randomization slot info Yinghai Lu
2015-07-07 20:20 ` [PATCH 14/42] x86, kaslr: Add two functions which will be used later Yinghai Lu
2015-07-07 20:20 ` [PATCH 15/42] x86, kaslr: Introduce fetch_random_virt_offset to randomize the kernel text mapping address Yinghai Lu
2015-07-07 20:20 ` [PATCH 16/42] x86, kaslr: Randomize physical and virtual address of kernel separately Yinghai Lu
2015-07-07 20:20 ` [PATCH 17/42] x86, kaslr: Add support of kernel physical address randomization above 4G Yinghai Lu
2015-07-07 20:20 ` [PATCH 18/42] x86, kaslr: Remove useless codes Yinghai Lu
2015-07-07 20:20 ` [PATCH 19/42] x86, kaslr: Allow random address could be below loaded address Yinghai Lu
2015-07-07 20:20 ` [PATCH 20/42] x86, boot: Add printf support for early console in compressed/misc.c Yinghai Lu
2015-07-07 20:20 ` [PATCH 21/42] x86, boot: Add more debug printout " Yinghai Lu
2015-07-07 20:20 ` [PATCH 22/42] x86, setup: Check early serial console per string instead of one char Yinghai Lu
2015-07-07 22:59 ` Kees Cook
2015-07-07 20:20 ` [PATCH 23/42] x86, setup: Use puts() instead of printf() in edd code Yinghai Lu
2015-07-07 20:20 ` [PATCH 24/42] x86: Setup early console as early as possible in x86_start_kernel() Yinghai Lu
2015-07-07 20:20 ` [PATCH 25/42] x86, boot: print compression suffix in decompress stage Yinghai Lu
2015-07-07 23:13 ` Kees Cook
2015-07-07 20:20 ` [PATCH 26/42] x86: remove not needed clear_page calling Yinghai Lu
2015-07-07 23:14 ` Kees Cook
2015-07-07 20:20 ` [PATCH 27/42] x86: restore end_of_ram to E820_RAM Yinghai Lu
2015-07-08 17:44 ` Matt Fleming
2015-07-09 1:41 ` Dan Williams
2015-07-09 7:45 ` Christoph Hellwig
2015-07-09 11:17 ` Matt Fleming
2015-07-07 20:20 ` [PATCH 28/42] x86, boot: Allow 64bit EFI kernel to be loaded above 4G Yinghai Lu
2015-07-07 23:12 ` Kees Cook
2015-07-08 18:00 ` Matt Fleming
2015-07-07 20:20 ` [PATCH 29/42] x86: Find correct 64 bit ramdisk address for microcode early update Yinghai Lu
2015-07-07 23:08 ` Kees Cook
2015-07-07 20:20 ` [PATCH 30/42] x86: Kill E820_RESERVED_KERN Yinghai Lu
2015-07-07 20:20 ` [PATCH 31/42] x86, efi: Copy SETUP_EFI data and access directly Yinghai Lu
2015-07-22 10:58 ` Matt Fleming
2015-07-22 10:58 ` Matt Fleming
2015-07-24 2:07 ` Dave Young
2015-07-24 2:07 ` Dave Young
2015-07-07 20:20 ` [PATCH 32/42] x86, of: Let add_dtb reserve setup_data locally Yinghai Lu
2015-07-07 20:20 ` [PATCH 33/42] x86, boot: Add add_pci handler for SETUP_PCI Yinghai Lu
2015-07-14 22:30 ` Bjorn Helgaas
2015-07-07 20:20 ` [PATCH 34/42] x86: Kill not used setup_data handling code Yinghai Lu
2015-07-07 20:20 ` [PATCH 35/42] x86, boot, PCI: Convert SETUP_PCI data to list Yinghai Lu
2015-07-14 22:35 ` Bjorn Helgaas
2015-07-15 1:57 ` Yinghai Lu
2015-07-07 20:20 ` [PATCH 36/42] x86, boot, PCI: Copy SETUP_PCI rom to kernel space Yinghai Lu
2015-07-07 20:20 ` [PATCH 37/42] x86, boot, PCI: Export SETUP_PCI data via sysfs Yinghai Lu
2015-07-07 20:20 ` [PATCH 38/42] x86: Fix typo in mark_rodata_ro Yinghai Lu
2015-07-07 23:05 ` Kees Cook
2015-07-07 20:20 ` [PATCH 39/42] x86, 64bit: add pfn_range_is_highmapped() Yinghai Lu
2015-07-07 20:20 ` [PATCH 40/42] x86, 64bit: remove highmap for not needed ranges Yinghai Lu
2015-07-07 23:17 ` Kees Cook
2015-07-07 20:20 ` [PATCH 41/42] x86, 64bit: Add __pa_high/__va_high Yinghai Lu
2015-07-07 20:20 ` [PATCH 42/42] x86: fix msr print again Yinghai Lu
2015-07-07 23:21 ` [PATCH 00/42] x86: updated patches for kaslr and setup_data etc for v4.3 Kees Cook
2015-10-02 20:16 ` Kees Cook
2016-02-06 11:50 ` Baoquan He
2016-02-09 4:31 ` Kees Cook
2016-02-09 4:31 ` [kernel-hardening] " Kees Cook
2016-02-15 7:29 ` Baoquan He
2016-02-15 7:29 ` [kernel-hardening] " Baoquan He
2016-02-16 23:50 ` Kees Cook
2016-02-16 23:50 ` [kernel-hardening] " Kees Cook
2015-07-08 10:51 ` Ingo Molnar
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=CAGXu5jL6gWML6AWGBGpA1GVMa9xBBeCHud5ciEoFYpbqGQzbrA@mail.gmail.com \
--to=keescook@chromium.org \
--cc=bhe@redhat.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=yinghai@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.