From: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
To: Yinghai Lu <yinghai-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Matt Fleming
<matt.fleming-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
"H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>,
Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Borislav Petkov <bp-l3A5Bk7waGM@public.gmane.org>,
Baoquan He <bhe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>,
Jiri Kosina <jkosina-AlSwsSmVLrQ@public.gmane.org>,
LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH v3 2/7] x86, boot: Move ZO to end of buffer
Date: Mon, 9 Mar 2015 17:54:01 -0700 [thread overview]
Message-ID: <CAGXu5jJFms+vYOtEpVAQ6iZXM45uYF70a=vgyb72T0uRkf8c0g@mail.gmail.com> (raw)
In-Reply-To: <1425766041-6551-3-git-send-email-yinghai-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
On Sat, Mar 7, 2015 at 2:07 PM, Yinghai Lu <yinghai-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
> Boris found data from boot stage can not be used kernel stage.
"... be used during kernel stage."
Also, can you give a specific example of this problem? (Which data, used how?)
> Bootloader allocate buffer according to init_size in hdr, and load the
> ZO (arch/x86/boot/compressed/vmlinux) from start of that buffer.
> During running of ZO, ZO move itself to the middle of buffer at
> z_extract_offset to make sure that decompressor would not have output
> overwrite input data before input data get consumed.
> After decompressor is called, VO (vmlinux) use whole buffer from start,
> and ZO code and data section is overlapped with VO bss section.
> And later VO/clear_bss() clear them before code in arch/x86/kernel/setup.c
> access them.
>
> To make the data survive that later, we should avoid the overlapping.
> At first move ZO close the end of buffer instead of middle of the buffer,
> that will move out ZO data out of VO bss area.
>
> Also after that we can find out where is data section of copied ZO
> instead of guessing. That will aslr mem_avoid array filling for
"That will make aslr mem_avoid array ..."
> new buffer seaching much simple.
>
> And rename z_extract_offset to z_min_extract_offset, as it is
> actually the minimum offset for extracting now.
>
> To keep the final real extract_offset to be page aligned like
> min_extract_offset, we need make VO _end and ZO _end both
> page aligned to make sure init_size always page aligned.
>
> Next patch will add ZO data size to init_size, so it will make sure
> ZO data is even out of VO brk area.
This seems like a reasonable idea, but I think the changes should be
noted/updated in misc.c since a lot of effort was made to make the
in-memory foot print as small as possible. These changes do expand the
size of the loaded kernel, IIUC. If not in this patch, maybe in 5/7?
-Kees
>
> Fixes: f47233c2d34f ("x86/mm/ASLR: Propagate base load address calculation")
> Cc: "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
> Cc: Matt Fleming <matt.fleming-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> Cc: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> Signed-off-by: Yinghai Lu <yinghai-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.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 cbed140..a9b56f1 100644
> --- a/arch/x86/boot/compressed/head_32.S
> +++ b/arch/x86/boot/compressed/head_32.S
> @@ -147,7 +147,9 @@ 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
> @@ -208,8 +210,13 @@ relocated:
> */
> /* push arguments for decompress_kernel: */
> pushl $z_output_len /* decompressed length */
> - 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 2884e0c..69015b5 100644
> --- a/arch/x86/boot/compressed/head_64.S
> +++ b/arch/x86/boot/compressed/head_64.S
> @@ -101,7 +101,9 @@ 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
> @@ -329,7 +331,9 @@ 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 b669ab6..c03b009 100644
> --- a/arch/x86/boot/compressed/mkpiggy.c
> +++ b/arch/x86/boot/compressed/mkpiggy.c
> @@ -80,11 +80,8 @@ 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 input_data, input_data_end\n");
> printf("input_data:\n");
> 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 9f6b934..0e8e4f7 100644
> --- a/arch/x86/kernel/asm-offsets.c
> +++ b/arch/x86/kernel/asm-offsets.c
> @@ -66,6 +66,7 @@ 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..ac25c7f 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:[~2015-03-10 0:54 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-07 22:07 [PATCH v3 0/7] x86, boot: clean up kasl Yinghai Lu
2015-03-07 22:07 ` [PATCH v3 1/7] x86, kaslr: Use init_size instead of run_size Yinghai Lu
[not found] ` <1425766041-6551-2-git-send-email-yinghai-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2015-03-09 12:49 ` Borislav Petkov
2015-03-09 15:58 ` Ingo Molnar
[not found] ` <20150309155813.GA21755-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-03-09 15:58 ` Borislav Petkov
2015-03-09 19:35 ` Yinghai Lu
2015-03-09 20:00 ` Borislav Petkov
[not found] ` <20150309200035.GK12732-fF5Pk5pvG8Y@public.gmane.org>
2015-03-09 20:06 ` Yinghai Lu
[not found] ` <CAE9FiQVEaeWZ2oggks8_jbS+dObZJLq7aEo9cFEqJNtOhWTNRw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-03-09 20:18 ` Borislav Petkov
[not found] ` <20150309201846.GM12732-fF5Pk5pvG8Y@public.gmane.org>
2015-03-09 21:28 ` Yinghai Lu
2015-03-10 0:42 ` Kees Cook
2015-03-13 12:27 ` Ingo Molnar
[not found] ` <20150313122756.GA28855-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-03-14 2:47 ` Yinghai Lu
[not found] ` <CAE9FiQXaRmJFdEUhyn2q0v=9ymdbqZWEo1pzo6iyaNupWEp5Xg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-03-14 7:53 ` Ingo Molnar
[not found] ` <20150314075357.GA8319-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-03-14 9:59 ` Borislav Petkov
[not found] ` <20150314095923.GA3114-fF5Pk5pvG8Y@public.gmane.org>
2015-03-16 10:06 ` [PATCH] Revert "x86/mm/ASLR: Propagate base load address calculation" Borislav Petkov
[not found] ` <20150316100628.GD22995-fF5Pk5pvG8Y@public.gmane.org>
2015-03-16 13:56 ` Jiri Kosina
2015-03-16 19:15 ` Yinghai Lu
2015-03-17 8:14 ` Ingo Molnar
2015-03-07 22:07 ` [PATCH v3 2/7] x86, boot: Move ZO to end of buffer Yinghai Lu
[not found] ` <1425766041-6551-3-git-send-email-yinghai-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2015-03-10 0:54 ` Kees Cook [this message]
2015-03-10 1:04 ` Yinghai Lu
[not found] ` <CAGXu5jJFms+vYOtEpVAQ6iZXM45uYF70a=vgyb72T0uRkf8c0g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-03-10 5:59 ` Borislav Petkov
2015-03-10 8:00 ` Borislav Petkov
[not found] ` <20150310080024.GB3535-fF5Pk5pvG8Y@public.gmane.org>
2015-03-10 9:34 ` Jiri Kosina
[not found] ` <alpine.LNX.2.00.1503101032560.26925-ztGlSCb7Y1iN3ZZ/Hiejyg@public.gmane.org>
2015-03-10 9:35 ` Borislav Petkov
2015-03-10 15:11 ` Yinghai Lu
[not found] ` <CAE9FiQVPLUPWPhZ4yROTECVKeLTNUMXOURoYx0sG_SGPfCNGQw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-03-10 15:13 ` Borislav Petkov
2015-03-10 16:59 ` Kees Cook
2015-03-07 22:07 ` [PATCH v3 3/7] x86, boot: Don't overlap VO with ZO data Yinghai Lu
2015-03-10 9:34 ` Borislav Petkov
[not found] ` <20150310093430.GC3535-fF5Pk5pvG8Y@public.gmane.org>
2015-03-10 15:05 ` Yinghai Lu
[not found] ` <CAE9FiQWauOdsZ=CBcVHfqTik1ePvW51uH7yy29MSvafOABTWZA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-03-10 15:10 ` Borislav Petkov
[not found] ` <20150310151035.GG3535-fF5Pk5pvG8Y@public.gmane.org>
2015-03-10 15:17 ` Yinghai Lu
2015-03-10 15:21 ` Borislav Petkov
[not found] ` <20150310152137.GI3535-fF5Pk5pvG8Y@public.gmane.org>
2015-03-10 15:42 ` Yinghai Lu
[not found] ` <CAE9FiQUQn0vdU_MNf79=oE=DSkUG4U54-taVfgPro1JqUA7BTQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-03-10 15:48 ` Borislav Petkov
[not found] ` <20150310154828.GJ3535-fF5Pk5pvG8Y@public.gmane.org>
2015-03-10 19:29 ` Yinghai Lu
2015-03-07 22:07 ` [PATCH v3 4/7] x86, kaslr: Access the correct kaslr_enabled variable Yinghai Lu
[not found] ` <1425766041-6551-5-git-send-email-yinghai-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2015-03-10 0:55 ` Kees Cook
2015-03-07 22:07 ` [PATCH v3 6/7] x86, boot: Split kernel_ident_mapping_init to another file Yinghai Lu
[not found] ` <1425766041-6551-7-git-send-email-yinghai-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2015-03-10 1:03 ` Kees Cook
2015-03-07 22:07 ` [PATCH v3 7/7] x86, kaslr, 64bit: Set new or extra ident_mapping Yinghai Lu
[not found] ` <1425766041-6551-8-git-send-email-yinghai-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2015-03-10 1:09 ` Kees Cook
[not found] ` <CAGXu5j+REYpi=hnf3s+F1Dd9nkXkvQ5w7wO_j_emmAM226VrGw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-03-10 1:14 ` Yinghai Lu
[not found] ` <CAE9FiQX=b38-mseWWeGg=eTFfbe1sH61PvXJYJYrsAF6Uxn8ow-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-03-10 6:54 ` Yinghai Lu
[not found] ` <1425766041-6551-1-git-send-email-yinghai-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2015-03-07 22:07 ` [PATCH v3 5/7] x86, kaslr: Consolidate mem_avoid array filling Yinghai Lu
[not found] ` <1425766041-6551-6-git-send-email-yinghai-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2015-03-10 1:00 ` Kees Cook
[not found] ` <CAGXu5j+exWabf=LdpkBtipcRYDVW=sH4LZf01P3RoSaKK7iYYA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-03-10 1:10 ` Yinghai Lu
[not found] ` <CAE9FiQX2Ee0gWhtDrQxi=NfwC3Vu9ZS_YLPC9qvR92htZfBcJg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-03-10 1:26 ` Kees Cook
2015-03-10 0:39 ` [PATCH v3 0/7] x86, boot: clean up kasl Kees Cook
[not found] ` <CAGXu5jJ-KVZTgd-bGdZvUwq0P2tfqo5S3L8S0JbWv0-aw3+Byw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-03-10 0:54 ` Yinghai Lu
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