* [PATCH 1/3] x86/KASLR: Update document about KERNEL_IMAGE_SIZE
2018-09-21 2:05 [PATCH 0/3] x86/mm/doc: Clean up mm.txt Baoquan He
@ 2018-09-21 2:05 ` Baoquan He
2018-09-21 2:05 ` [PATCH 2/3] x86/mm/doc: Clean up the memory region layout descriptions Baoquan He
` (2 subsequent siblings)
3 siblings, 0 replies; 12+ messages in thread
From: Baoquan He @ 2018-09-21 2:05 UTC (permalink / raw)
To: mingo, tglx, hpa
Cc: linux-kernel, kirill.shutemov, x86, thgarnie, corbet, linux-doc,
peterz, Baoquan He
Currently CONFIG_RANDOMIZE_BASE=y is default set, update the relevant
document about KERNEL_IMAGE_SIZE.
Signed-off-by: Baoquan He <bhe@redhat.com>
---
arch/x86/include/asm/page_64_types.h | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index 6afac386a434..2288ceabdb9c 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -61,9 +61,10 @@
/*
* Kernel image size is limited to 1GiB due to the fixmap living in the
* next 1GiB (see level2_kernel_pgt in arch/x86/kernel/head_64.S). Use
- * 512MiB by default, leaving 1.5GiB for modules once the page tables
- * are fully set up. If kernel ASLR is configured, it can extend the
- * kernel page table mapping, reducing the size of the modules area.
+ * 1 GiB by default, leaving 1 GiB for modules once the page tables are
+ * fully set up. If kernel ASLR is not configured, it can shrink the
+ * kernel page table mapping to decrease the size of kernel area to 512
+ * MiB, increase the size of the modules area to 1.5 GiB.
*/
#if defined(CONFIG_RANDOMIZE_BASE)
#define KERNEL_IMAGE_SIZE (1024 * 1024 * 1024)
--
2.13.6
^ permalink raw reply related [flat|nested] 12+ messages in thread* [PATCH 2/3] x86/mm/doc: Clean up the memory region layout descriptions
2018-09-21 2:05 [PATCH 0/3] x86/mm/doc: Clean up mm.txt Baoquan He
2018-09-21 2:05 ` [PATCH 1/3] x86/KASLR: Update document about KERNEL_IMAGE_SIZE Baoquan He
@ 2018-09-21 2:05 ` Baoquan He
2018-09-21 2:05 ` [PATCH 3/3] x86/doc/kaslr.txt: Create a separate part of document abourt KASLR at the end of file Baoquan He
2018-09-27 0:02 ` [PATCH 0/3] x86/mm/doc: Clean up mm.txt Baoquan He
3 siblings, 0 replies; 12+ messages in thread
From: Baoquan He @ 2018-09-21 2:05 UTC (permalink / raw)
To: mingo, tglx, hpa
Cc: linux-kernel, kirill.shutemov, x86, thgarnie, corbet, linux-doc,
peterz, Baoquan He
In Documentation/x86/x86_64/mm.txt, the style of descritions about
memory region layout is a little confusing:
- mix size in TB with 'bits'
- sometimes mention a size in the description and sometimes not
- sometimes list holes by address, sometimes only as an 'unused hole' line
So fix them to make them in consistent style.
Signed-off-by: Baoquan He <bhe@redhat.com>
---
Documentation/x86/x86_64/mm.txt | 76 ++++++++++++++++++++---------------------
1 file changed, 38 insertions(+), 38 deletions(-)
diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt
index 5432a96d31ff..fc1da95e629d 100644
--- a/Documentation/x86/x86_64/mm.txt
+++ b/Documentation/x86/x86_64/mm.txt
@@ -1,52 +1,52 @@
Virtual memory map with 4 level page tables:
-0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm
-hole caused by [47:63] sign extension
-ffff800000000000 - ffff87ffffffffff (=43 bits) guard hole, reserved for hypervisor
-ffff880000000000 - ffffc7ffffffffff (=64 TB) direct mapping of all phys. memory
-ffffc80000000000 - ffffc8ffffffffff (=40 bits) hole
-ffffc90000000000 - ffffe8ffffffffff (=45 bits) vmalloc/ioremap space
-ffffe90000000000 - ffffe9ffffffffff (=40 bits) hole
-ffffea0000000000 - ffffeaffffffffff (=40 bits) virtual memory map (1TB)
-... unused hole ...
-ffffec0000000000 - fffffbffffffffff (=44 bits) kasan shadow memory (16TB)
-... unused hole ...
+0000000000000000 - 00007fffffffffff (=47 bits, 128 TB) user space, different per mm
+ hole caused by [47:63] sign extension
+ffff800000000000 - ffff87ffffffffff (=43 bits, 8 TB) guard hole, reserved for hypervisor
+ffff880000000000 - ffffc7ffffffffff (=46 bits, 64 TB) direct mapping of all phys. memory (page_offset_base)
+ffffc80000000000 - ffffc8ffffffffff (=40 bits, 1 TB) unused hole
+ffffc90000000000 - ffffe8ffffffffff (=45 bits, 32 TB) vmalloc/ioremap space (vmalloc_base)
+ffffe90000000000 - ffffe9ffffffffff (=40 bits, 1 TB) unused hole
+ffffea0000000000 - ffffeaffffffffff (=40 bits, 1 TB) virtual memory map (vmemmap_base)
+ffffeb0000000000 - ffffebffffffffff (=40 bits, 1 TB) unused hole
+ffffec0000000000 - fffffbffffffffff (=44 bits, 16 TB) kasan shadow memory
+fffffc0000000000 - fffffdffffffffff (=41 bits, 2 TB) unused hole
vaddr_end for KASLR
-fffffe0000000000 - fffffe7fffffffff (=39 bits) cpu_entry_area mapping
-fffffe8000000000 - fffffeffffffffff (=39 bits) LDT remap for PTI
-ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks
-... unused hole ...
-ffffffef00000000 - fffffffeffffffff (=64 GB) EFI region mapping space
-... unused hole ...
-ffffffff80000000 - ffffffff9fffffff (=512 MB) kernel text mapping, from phys 0
-ffffffffa0000000 - fffffffffeffffff (1520 MB) module mapping space
+fffffe0000000000 - fffffe7fffffffff (=39 bits, 512 GB) cpu_entry_area mapping
+fffffe8000000000 - fffffeffffffffff (=39 bits, 512 GB) LDT remap for PTI
+ffffff0000000000 - ffffff7fffffffff (=39 bits, 512 GB) %esp fixup stacks
+ffffff8000000000 - fffffffeefffffff (~39 bits, ~507 GB) unused hole
+ffffffef00000000 - fffffffeffffffff (=36 bits, 64 GB) EFI region mapping space
+ffffffff00000000 - ffffffff7fffffff (=31 bits, 2 GB) unused hole
+ffffffff80000000 - ffffffff9fffffff (=29 bits, 512 MB) kernel text mapping, from phys 0
+ffffffffa0000000 - fffffffffeffffff (~31 bits, 1520 MB) module mapping space
[fixmap start] - ffffffffff5fffff kernel-internal fixmap range
ffffffffff600000 - ffffffffff600fff (=4 kB) legacy vsyscall ABI
ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
Virtual memory map with 5 level page tables:
-0000000000000000 - 00ffffffffffffff (=56 bits) user space, different per mm
-hole caused by [56:63] sign extension
-ff00000000000000 - ff0fffffffffffff (=52 bits) guard hole, reserved for hypervisor
-ff10000000000000 - ff8fffffffffffff (=55 bits) direct mapping of all phys. memory
-ff90000000000000 - ff9fffffffffffff (=52 bits) LDT remap for PTI
-ffa0000000000000 - ffd1ffffffffffff (=54 bits) vmalloc/ioremap space (12800 TB)
-ffd2000000000000 - ffd3ffffffffffff (=49 bits) hole
-ffd4000000000000 - ffd5ffffffffffff (=49 bits) virtual memory map (512TB)
-... unused hole ...
-ffdf000000000000 - fffffc0000000000 (=53 bits) kasan shadow memory (8PB)
-... unused hole ...
+0000000000000000 - 00ffffffffffffff (=56 bits, 64 PB) user space, different per mm
+ hole caused by [56:63] sign extension
+ff00000000000000 - ff0fffffffffffff (=52 bits, 4 PB) guard hole, reserved for hypervisor
+ff10000000000000 - ff8fffffffffffff (=55 bits, 32 PB) direct mapping of all phys. memory (page_offset_base)
+ff90000000000000 - ff9fffffffffffff (=52 bits, 4 PB) LDT remap for PTI
+ffa0000000000000 - ffd1ffffffffffff (=53 bits, 12800 TB) vmalloc/ioremap space (vmalloc_base)
+ffd2000000000000 - ffd3ffffffffffff (=49 bits, 512 TB) unused hole
+ffd4000000000000 - ffd5ffffffffffff (=49 bits, 512 TB) virtual memory map (vmemmap_base)
+ffd6000000000000 - ffdeffffffffffff (~51 bits, 2304 TB) unused hole
+ffdf000000000000 - fffffdffffffffff (~53 bits, ~8 PB) kasan shadow memory
+fffffc0000000000 - fffffdffffffffff (=41 bits, 2 TB) unused hole
vaddr_end for KASLR
-fffffe0000000000 - fffffe7fffffffff (=39 bits) cpu_entry_area mapping
-... unused hole ...
-ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks
-... unused hole ...
-ffffffef00000000 - fffffffeffffffff (=64 GB) EFI region mapping space
-... unused hole ...
-ffffffff80000000 - ffffffff9fffffff (=512 MB) kernel text mapping, from phys 0
-ffffffffa0000000 - fffffffffeffffff (1520 MB) module mapping space
+fffffe0000000000 - fffffe7fffffffff (=39 bits, 512 GB) cpu_entry_area mapping
+fffffe8000000000 - fffffeffffffffff (=39 bits, 512 GB) unused hole
+ffffff0000000000 - ffffff7fffffffff (=39 bits, 512 GB) %esp fixup stacks
+ffffff8000000000 - ffffffeeffffffff (~39 bits, 444 GB) unused hole
+ffffffef00000000 - fffffffeffffffff (=36 bits, 64 GB) EFI region mapping space
+ffffffff00000000 - ffffffff7fffffff (31 bits, 2 GB) unused hole
+ffffffff80000000 - ffffffff9fffffff (=29 bits, 512 MB) kernel text mapping, from phys 0
+ffffffffa0000000 - fffffffffeffffff (~31 bits, 1520 MB) module mapping space
[fixmap start] - ffffffffff5fffff kernel-internal fixmap range
ffffffffff600000 - ffffffffff600fff (=4 kB) legacy vsyscall ABI
ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
--
2.13.6
^ permalink raw reply related [flat|nested] 12+ messages in thread
* [PATCH 3/3] x86/doc/kaslr.txt: Create a separate part of document abourt KASLR at the end of file
2018-09-21 2:05 [PATCH 0/3] x86/mm/doc: Clean up mm.txt Baoquan He
2018-09-21 2:05 ` [PATCH 1/3] x86/KASLR: Update document about KERNEL_IMAGE_SIZE Baoquan He
2018-09-21 2:05 ` [PATCH 2/3] x86/mm/doc: Clean up the memory region layout descriptions Baoquan He
@ 2018-09-21 2:05 ` Baoquan He
2018-09-21 3:19 ` Baoquan He
2018-09-21 3:21 ` [PATCH v2 " Baoquan He
2018-09-27 0:02 ` [PATCH 0/3] x86/mm/doc: Clean up mm.txt Baoquan He
3 siblings, 2 replies; 12+ messages in thread
From: Baoquan He @ 2018-09-21 2:05 UTC (permalink / raw)
To: mingo, tglx, hpa
Cc: linux-kernel, kirill.shutemov, x86, thgarnie, corbet, linux-doc,
peterz, Baoquan He
Take the original content as the first part to only list static mm layout
tables in non-KASLR case. Then add KASLR document at the end.
Signed-off-by: Baoquan He <bhe@redhat.com>
---
Documentation/x86/x86_64/mm.txt | 62 +++++++++++++++++++++++++++++++++++------
1 file changed, 54 insertions(+), 8 deletions(-)
diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt
index fc1da95e629d..04b058e20dbf 100644
--- a/Documentation/x86/x86_64/mm.txt
+++ b/Documentation/x86/x86_64/mm.txt
@@ -1,4 +1,6 @@
+MM layout in non-KASLR case:
+
Virtual memory map with 4 level page tables:
0000000000000000 - 00007fffffffffff (=47 bits, 128 TB) user space, different per mm
@@ -12,7 +14,6 @@ ffffea0000000000 - ffffeaffffffffff (=40 bits, 1 TB) virtual memory map (vmemmap
ffffeb0000000000 - ffffebffffffffff (=40 bits, 1 TB) unused hole
ffffec0000000000 - fffffbffffffffff (=44 bits, 16 TB) kasan shadow memory
fffffc0000000000 - fffffdffffffffff (=41 bits, 2 TB) unused hole
- vaddr_end for KASLR
fffffe0000000000 - fffffe7fffffffff (=39 bits, 512 GB) cpu_entry_area mapping
fffffe8000000000 - fffffeffffffffff (=39 bits, 512 GB) LDT remap for PTI
ffffff0000000000 - ffffff7fffffffff (=39 bits, 512 GB) %esp fixup stacks
@@ -38,7 +39,6 @@ ffd4000000000000 - ffd5ffffffffffff (=49 bits, 512 TB) virtual memory map (vmemm
ffd6000000000000 - ffdeffffffffffff (~51 bits, 2304 TB) unused hole
ffdf000000000000 - fffffdffffffffff (~53 bits, ~8 PB) kasan shadow memory
fffffc0000000000 - fffffdffffffffff (=41 bits, 2 TB) unused hole
- vaddr_end for KASLR
fffffe0000000000 - fffffe7fffffffff (=39 bits, 512 GB) cpu_entry_area mapping
fffffe8000000000 - fffffeffffffffff (=39 bits, 512 GB) unused hole
ffffff0000000000 - ffffff7fffffffff (=39 bits, 512 GB) %esp fixup stacks
@@ -70,10 +70,56 @@ memory window (this size is arbitrary, it can be raised later if needed).
The mappings are not part of any other kernel PGD and are only available
during EFI runtime calls.
-Note that if CONFIG_RANDOMIZE_MEMORY is enabled, the direct mapping of all
-physical memory, vmalloc/ioremap space and virtual memory map are randomized.
-Their order is preserved but their base will be offset early at boot time.
+KASLR
+=========================================================================
+
+Kernel Address Space Layout Randomization (KASLR) consists of two parts
+which work together to enhance the security of the Linux kernel:
+
+ - Kernel text KASLR
+ - Memory region KASLR
+
+Kernel text KASLR
+-----------------
+The physical address and virtual address of kernel text itself are
+randomized to a different position separately. The physical address of
+the kernel can be anywhere under 64TB, while the virtual address of the
+kernel is restricted between [0xffffffff80000000, ffffffffbfffffff],
+the 1GB space.
+
+ffffffff80000000 - ffffffffbfffffff (1 GB) kernel text mapping, from phys 0
+ffffffffc0000000 - fffffffffeffffff (1520 MB) module mapping space
+
+Note: The kernel text KASLR uses 1 GB space to randomize the position of
+kernel image, and it's defalutly enabled. If KASLR config option
+CONFIG_RANDOMIZE_BASE is not enabled, the space for kernel image will be
+shrink to 512 MB, increase the size of modules area to 1.5 GB.
+
+Memory region KASLR
+-------------------
+If CONFIG_RANDOMIZE_MEMORY is enabled, the below three memory regions
+are randomized. Their order is preserved but their base will be offset
+early at boot time.
+
+ - direct mapping region
+ - vmalloc region
+ - vmemmap region
+
+The KASLR address range must not overlap with anything except the KASAN
+shadow area, which is correct as KASAN disables KASLR.
+
+So from the original starting address of the direct mapping region for physical
+RAM to the starting address of the cpu_entry_area mapping region, namely
+[0xffff880000000000 - 0xfffffdffffffffff], the scope of 118 TB in all is
+the virtual address space where memory region KASLR can be allowed to move
+those memory regions around. After KASLR manipulation is done, their layout
+looks like:
-Be very careful vs. KASLR when changing anything here. The KASLR address
-range must not overlap with anything except the KASAN shadow area, which is
-correct as KASAN disables KASLR.
+Name Starting address Size Aligned
+-----------------------------------------------------------------------------------------------
+direct mapping page_offset_base [actual size of system RAM + 10 TB padding] 1 GB
+*guard hole random random 1 GB
+vmalloc vmalloc_base 32 TB 1 GB
+*guard hole random random 1 GB
+vmemmap vmemmap_base 1 TB 1 GB
+*guard hole random random 1 GB
--
2.13.6
^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH 3/3] x86/doc/kaslr.txt: Create a separate part of document abourt KASLR at the end of file
2018-09-21 2:05 ` [PATCH 3/3] x86/doc/kaslr.txt: Create a separate part of document abourt KASLR at the end of file Baoquan He
@ 2018-09-21 3:19 ` Baoquan He
2018-09-21 3:21 ` [PATCH v2 " Baoquan He
1 sibling, 0 replies; 12+ messages in thread
From: Baoquan He @ 2018-09-21 3:19 UTC (permalink / raw)
To: mingo, tglx, hpa
Cc: linux-kernel, kirill.shutemov, x86, thgarnie, corbet, linux-doc, peterz
On 09/21/18 at 10:05am, Baoquan He wrote:
> +Name Starting address Size Aligned
> +-----------------------------------------------------------------------------------------------
> +direct mapping page_offset_base [actual size of system RAM + 10 TB padding] 1 GB
> +*guard hole random random 1 GB
> +vmalloc vmalloc_base 32 TB 1 GB
> +*guard hole random random 1 GB
> +vmemmap vmemmap_base 1 TB 1 GB
> +*guard hole random random 1 GB
OK, seems tab is uncontrollable, I will use space instead.
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH v2 3/3] x86/doc/kaslr.txt: Create a separate part of document abourt KASLR at the end of file
2018-09-21 2:05 ` [PATCH 3/3] x86/doc/kaslr.txt: Create a separate part of document abourt KASLR at the end of file Baoquan He
2018-09-21 3:19 ` Baoquan He
@ 2018-09-21 3:21 ` Baoquan He
2018-09-21 5:23 ` Baoquan He
2018-09-21 5:29 ` [PATCH v3 " Baoquan He
1 sibling, 2 replies; 12+ messages in thread
From: Baoquan He @ 2018-09-21 3:21 UTC (permalink / raw)
To: mingo, tglx, hpa
Cc: linux-kernel, kirill.shutemov, x86, thgarnie, corbet, linux-doc, peterz
Take the original content as the first part to only list static mm layout
tables in non-KASLR case. Then add KASLR document at the end.
Signed-off-by: Baoquan He <bhe@redhat.com>
---
Documentation/x86/x86_64/mm.txt | 62 +++++++++++++++++++++++++++++++++++------
1 file changed, 54 insertions(+), 8 deletions(-)
diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt
index fc1da95e629d..58187614c7ca 100644
--- a/Documentation/x86/x86_64/mm.txt
+++ b/Documentation/x86/x86_64/mm.txt
@@ -1,4 +1,6 @@
+MM layout in non-KASLR case:
+
Virtual memory map with 4 level page tables:
0000000000000000 - 00007fffffffffff (=47 bits, 128 TB) user space, different per mm
@@ -12,7 +14,6 @@ ffffea0000000000 - ffffeaffffffffff (=40 bits, 1 TB) virtual memory map (vmemmap
ffffeb0000000000 - ffffebffffffffff (=40 bits, 1 TB) unused hole
ffffec0000000000 - fffffbffffffffff (=44 bits, 16 TB) kasan shadow memory
fffffc0000000000 - fffffdffffffffff (=41 bits, 2 TB) unused hole
- vaddr_end for KASLR
fffffe0000000000 - fffffe7fffffffff (=39 bits, 512 GB) cpu_entry_area mapping
fffffe8000000000 - fffffeffffffffff (=39 bits, 512 GB) LDT remap for PTI
ffffff0000000000 - ffffff7fffffffff (=39 bits, 512 GB) %esp fixup stacks
@@ -38,7 +39,6 @@ ffd4000000000000 - ffd5ffffffffffff (=49 bits, 512 TB) virtual memory map (vmemm
ffd6000000000000 - ffdeffffffffffff (~51 bits, 2304 TB) unused hole
ffdf000000000000 - fffffdffffffffff (~53 bits, ~8 PB) kasan shadow memory
fffffc0000000000 - fffffdffffffffff (=41 bits, 2 TB) unused hole
- vaddr_end for KASLR
fffffe0000000000 - fffffe7fffffffff (=39 bits, 512 GB) cpu_entry_area mapping
fffffe8000000000 - fffffeffffffffff (=39 bits, 512 GB) unused hole
ffffff0000000000 - ffffff7fffffffff (=39 bits, 512 GB) %esp fixup stacks
@@ -70,10 +70,56 @@ memory window (this size is arbitrary, it can be raised later if needed).
The mappings are not part of any other kernel PGD and are only available
during EFI runtime calls.
-Note that if CONFIG_RANDOMIZE_MEMORY is enabled, the direct mapping of all
-physical memory, vmalloc/ioremap space and virtual memory map are randomized.
-Their order is preserved but their base will be offset early at boot time.
+KASLR
+=========================================================================
+
+Kernel Adress Space Layout Randomization (KASLR) consists of two parts
+which work together to enhance the security of the Linux kernel:
+
+ - Kernel text KASLR
+ - Memory region KASLR
+
+Kernel text KASLR
+-----------------
+The physical address and virtual address of kernel text itself are
+randomized to a different position separately. The physical address of
+the kernel can be anywhere under 64TB, while the virtual address of the
+kernel is restricted between [0xffffffff80000000, ffffffffbfffffff],
+the 1GB space.
+
+ffffffff80000000 - ffffffffbfffffff (1 GB) kernel text mapping, from phys 0
+ffffffffc0000000 - fffffffffeffffff (1520 MB) module mapping space
+
+Note: The kernel text KASLR uses 1 GB space to randomize the position of
+kernel image, and it's defalutly enabled. If KASLR config option
+CONFIG_RANDOMIZE_BASE is not enabled, the space for kernel image will be
+shrink to 512 MB, increase the size of modules area to 1.5 GB.
+
+Memory region KASLR
+-------------------
+If CONFIG_RANDOMIZE_MEMORY is enabled, the below three memory regions
+are randomized. Their order is preserved but their base will be offset
+early at boot time.
+
+ - direct mapping region
+ - vmalloc region
+ - vmemmap region
+
+The KASLR address range must not overlap with anything except the KASAN
+shadow area, which is correct as KASAN disables KASLR.
+
+So from the original starting address of the direct mapping region for physical
+RAM to the starting address of the cpu_entry_area mapping region, namely
+[0xffff880000000000 - 0xfffffdffffffffff], the scope of 118 TB in all is
+the virtual address space where memory region KASLR can be allowed to move
+those memory regions around. After KASLR manipulation is done, their layout
+looks like:
-Be very careful vs. KASLR when changing anything here. The KASLR address
-range must not overlap with anything except the KASAN shadow area, which is
-correct as KASAN disables KASLR.
+Name Starting address Size Aligned
+-----------------------------------------------------------------------------------------------
+direct mapping page_offset_base [actual size of system RAM + 10 TB padding] 1 GB
+*guard hole random random 1 GB
+vmalloc vmalloc_base 32 TB 1 GB
+*guard hole random random 1 GB
+vmemmap vmemmap_base 1 TB 1 GB
+*guard hole random random 1 GB
--
2.13.6
^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH v2 3/3] x86/doc/kaslr.txt: Create a separate part of document abourt KASLR at the end of file
2018-09-21 3:21 ` [PATCH v2 " Baoquan He
@ 2018-09-21 5:23 ` Baoquan He
2018-09-21 5:29 ` [PATCH v3 " Baoquan He
1 sibling, 0 replies; 12+ messages in thread
From: Baoquan He @ 2018-09-21 5:23 UTC (permalink / raw)
To: mingo, tglx, hpa
Cc: linux-kernel, kirill.shutemov, x86, thgarnie, corbet, linux-doc, peterz
On 09/21/18 at 11:21am, Baoquan He wrote:
> Take the original content as the first part to only list static mm layout
> tables in non-KASLR case. Then add KASLR document at the end.
>
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
> Documentation/x86/x86_64/mm.txt | 62 +++++++++++++++++++++++++++++++++++------
> 1 file changed, 54 insertions(+), 8 deletions(-)
>
> diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt
> index fc1da95e629d..58187614c7ca 100644
> --- a/Documentation/x86/x86_64/mm.txt
> +++ b/Documentation/x86/x86_64/mm.txt
> @@ -1,4 +1,6 @@
>
> +MM layout in non-KASLR case:
> +
> Virtual memory map with 4 level page tables:
>
> 0000000000000000 - 00007fffffffffff (=47 bits, 128 TB) user space, different per mm
> @@ -12,7 +14,6 @@ ffffea0000000000 - ffffeaffffffffff (=40 bits, 1 TB) virtual memory map (vmemmap
> ffffeb0000000000 - ffffebffffffffff (=40 bits, 1 TB) unused hole
> ffffec0000000000 - fffffbffffffffff (=44 bits, 16 TB) kasan shadow memory
> fffffc0000000000 - fffffdffffffffff (=41 bits, 2 TB) unused hole
> - vaddr_end for KASLR
> fffffe0000000000 - fffffe7fffffffff (=39 bits, 512 GB) cpu_entry_area mapping
> fffffe8000000000 - fffffeffffffffff (=39 bits, 512 GB) LDT remap for PTI
> ffffff0000000000 - ffffff7fffffffff (=39 bits, 512 GB) %esp fixup stacks
> @@ -38,7 +39,6 @@ ffd4000000000000 - ffd5ffffffffffff (=49 bits, 512 TB) virtual memory map (vmemm
> ffd6000000000000 - ffdeffffffffffff (~51 bits, 2304 TB) unused hole
> ffdf000000000000 - fffffdffffffffff (~53 bits, ~8 PB) kasan shadow memory
> fffffc0000000000 - fffffdffffffffff (=41 bits, 2 TB) unused hole
> - vaddr_end for KASLR
> fffffe0000000000 - fffffe7fffffffff (=39 bits, 512 GB) cpu_entry_area mapping
> fffffe8000000000 - fffffeffffffffff (=39 bits, 512 GB) unused hole
> ffffff0000000000 - ffffff7fffffffff (=39 bits, 512 GB) %esp fixup stacks
> @@ -70,10 +70,56 @@ memory window (this size is arbitrary, it can be raised later if needed).
> The mappings are not part of any other kernel PGD and are only available
> during EFI runtime calls.
>
> -Note that if CONFIG_RANDOMIZE_MEMORY is enabled, the direct mapping of all
> -physical memory, vmalloc/ioremap space and virtual memory map are randomized.
> -Their order is preserved but their base will be offset early at boot time.
> +KASLR
> +=========================================================================
> +
> +Kernel Adress Space Layout Randomization (KASLR) consists of two parts
> +which work together to enhance the security of the Linux kernel:
> +
> + - Kernel text KASLR
> + - Memory region KASLR
> +
> +Kernel text KASLR
> +-----------------
> +The physical address and virtual address of kernel text itself are
> +randomized to a different position separately. The physical address of
> +the kernel can be anywhere under 64TB, while the virtual address of the
~~~ in 4-level paging mode
> +kernel is restricted between [0xffffffff80000000, ffffffffbfffffff],
> +the 1GB space.
> +
> +ffffffff80000000 - ffffffffbfffffff (1 GB) kernel text mapping, from phys 0
> +ffffffffc0000000 - fffffffffeffffff (1520 MB) module mapping space
1 GB too, will repost.
> +
> +Note: The kernel text KASLR uses 1 GB space to randomize the position of
> +kernel image, and it's defalutly enabled. If KASLR config option
> +CONFIG_RANDOMIZE_BASE is not enabled, the space for kernel image will be
> +shrink to 512 MB, increase the size of modules area to 1.5 GB.
> +
> +Memory region KASLR
> +-------------------
> +If CONFIG_RANDOMIZE_MEMORY is enabled, the below three memory regions
> +are randomized. Their order is preserved but their base will be offset
> +early at boot time.
> +
> + - direct mapping region
> + - vmalloc region
> + - vmemmap region
> +
> +The KASLR address range must not overlap with anything except the KASAN
> +shadow area, which is correct as KASAN disables KASLR.
> +
> +So from the original starting address of the direct mapping region for physical
> +RAM to the starting address of the cpu_entry_area mapping region, namely
> +[0xffff880000000000 - 0xfffffdffffffffff], the scope of 118 TB in all is
> +the virtual address space where memory region KASLR can be allowed to move
> +those memory regions around. After KASLR manipulation is done, their layout
> +looks like:
>
> -Be very careful vs. KASLR when changing anything here. The KASLR address
> -range must not overlap with anything except the KASAN shadow area, which is
> -correct as KASAN disables KASLR.
> +Name Starting address Size Aligned
> +-----------------------------------------------------------------------------------------------
> +direct mapping page_offset_base [actual size of system RAM + 10 TB padding] 1 GB
> +*guard hole random random 1 GB
> +vmalloc vmalloc_base 32 TB 1 GB
> +*guard hole random random 1 GB
> +vmemmap vmemmap_base 1 TB 1 GB
> +*guard hole random random 1 GB
> --
> 2.13.6
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH v3 3/3] x86/doc/kaslr.txt: Create a separate part of document abourt KASLR at the end of file
2018-09-21 3:21 ` [PATCH v2 " Baoquan He
2018-09-21 5:23 ` Baoquan He
@ 2018-09-21 5:29 ` Baoquan He
1 sibling, 0 replies; 12+ messages in thread
From: Baoquan He @ 2018-09-21 5:29 UTC (permalink / raw)
To: mingo, tglx, hpa
Cc: linux-kernel, kirill.shutemov, x86, thgarnie, corbet, linux-doc, peterz
Take the original content as the first part to only list static mm layout
tables in non-KASLR case. Then add KASLR document at the end.
Signed-off-by: Baoquan He <bhe@redhat.com>
---
Documentation/x86/x86_64/mm.txt | 64 +++++++++++++++++++++++++++++++++++------
1 file changed, 56 insertions(+), 8 deletions(-)
diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt
index fc1da95e629d..8c03d6ad3623 100644
--- a/Documentation/x86/x86_64/mm.txt
+++ b/Documentation/x86/x86_64/mm.txt
@@ -1,4 +1,7 @@
+MM layout in non-KASLR case:
+=================================
+
Virtual memory map with 4 level page tables:
0000000000000000 - 00007fffffffffff (=47 bits, 128 TB) user space, different per mm
@@ -12,7 +15,6 @@ ffffea0000000000 - ffffeaffffffffff (=40 bits, 1 TB) virtual memory map (vmemmap
ffffeb0000000000 - ffffebffffffffff (=40 bits, 1 TB) unused hole
ffffec0000000000 - fffffbffffffffff (=44 bits, 16 TB) kasan shadow memory
fffffc0000000000 - fffffdffffffffff (=41 bits, 2 TB) unused hole
- vaddr_end for KASLR
fffffe0000000000 - fffffe7fffffffff (=39 bits, 512 GB) cpu_entry_area mapping
fffffe8000000000 - fffffeffffffffff (=39 bits, 512 GB) LDT remap for PTI
ffffff0000000000 - ffffff7fffffffff (=39 bits, 512 GB) %esp fixup stacks
@@ -38,7 +40,6 @@ ffd4000000000000 - ffd5ffffffffffff (=49 bits, 512 TB) virtual memory map (vmemm
ffd6000000000000 - ffdeffffffffffff (~51 bits, 2304 TB) unused hole
ffdf000000000000 - fffffdffffffffff (~53 bits, ~8 PB) kasan shadow memory
fffffc0000000000 - fffffdffffffffff (=41 bits, 2 TB) unused hole
- vaddr_end for KASLR
fffffe0000000000 - fffffe7fffffffff (=39 bits, 512 GB) cpu_entry_area mapping
fffffe8000000000 - fffffeffffffffff (=39 bits, 512 GB) unused hole
ffffff0000000000 - ffffff7fffffffff (=39 bits, 512 GB) %esp fixup stacks
@@ -70,10 +71,57 @@ memory window (this size is arbitrary, it can be raised later if needed).
The mappings are not part of any other kernel PGD and are only available
during EFI runtime calls.
-Note that if CONFIG_RANDOMIZE_MEMORY is enabled, the direct mapping of all
-physical memory, vmalloc/ioremap space and virtual memory map are randomized.
-Their order is preserved but their base will be offset early at boot time.
+KASLR
+=========================================================================
+
+Kernel Adress Space Layout Randomization (KASLR) consists of two parts
+which work together to enhance the security of the Linux kernel:
+
+ - Kernel text KASLR
+ - Memory region KASLR
+
+Kernel text KASLR
+-----------------
+The physical address and virtual address of kernel text itself are
+randomized to a different position separately. The physical address of
+the kernel can be anywhere, under 64TB at most in 4-level paging mode,
+and under 4 PB in 5-level paging mode, while the virtual address of the
+kernel is restricted between [0xffffffff80000000, ffffffffbfffffff],
+the 1GB space.
+
+ffffffff80000000 - ffffffffbfffffff (1 GB) kernel text mapping, from phys 0
+ffffffffc0000000 - fffffffffeffffff (1 GB) module mapping space
+
+Note: The kernel text KASLR uses 1 GB space to randomize the position of
+kernel image, and it's defalutly enabled. If KASLR config option
+CONFIG_RANDOMIZE_BASE is not enabled, the space for kernel image will be
+shrink to 512 MB, increase the size of modules area to 1.5 GB.
+
+Memory region KASLR
+-------------------
+If CONFIG_RANDOMIZE_MEMORY is enabled, the below three memory regions
+are randomized. Their order is preserved but their base will be offset
+early at boot time.
+
+ - direct mapping region
+ - vmalloc region
+ - vmemmap region
+
+The KASLR address range must not overlap with anything except the KASAN
+shadow area, which is correct as KASAN disables KASLR.
+
+So from the original starting address of the direct mapping region for physical
+RAM to the starting address of the cpu_entry_area mapping region, namely
+[0xffff880000000000 - 0xfffffdffffffffff], the scope of 118 TB in all is
+the virtual address space where memory region KASLR can be allowed to move
+those memory regions around. After KASLR manipulation is done, their layout
+looks like:
-Be very careful vs. KASLR when changing anything here. The KASLR address
-range must not overlap with anything except the KASAN shadow area, which is
-correct as KASAN disables KASLR.
+Name Starting address Size Aligned
+-----------------------------------------------------------------------------------------------
+direct mapping page_offset_base [actual size of system RAM + 10 TB padding] 1 GB
+*guard hole random random 1 GB
+vmalloc vmalloc_base 32 TB 1 GB
+*guard hole random random 1 GB
+vmemmap vmemmap_base 1 TB 1 GB
+*guard hole random random 1 GB
--
2.13.6
^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH 0/3] x86/mm/doc: Clean up mm.txt
2018-09-21 2:05 [PATCH 0/3] x86/mm/doc: Clean up mm.txt Baoquan He
` (2 preceding siblings ...)
2018-09-21 2:05 ` [PATCH 3/3] x86/doc/kaslr.txt: Create a separate part of document abourt KASLR at the end of file Baoquan He
@ 2018-09-27 0:02 ` Baoquan He
3 siblings, 0 replies; 12+ messages in thread
From: Baoquan He @ 2018-09-27 0:02 UTC (permalink / raw)
To: mingo, tglx, hpa
Cc: linux-kernel, kirill.shutemov, x86, thgarnie, corbet, linux-doc, peterz
On 09/21/18 at 10:05am, Baoquan He wrote:
> This clean up is suggested by Ingo.
This series is messy, have sent v2. So NACK this v1 series.
>
> It firstly fix the confusions in mm layout tables by unifying
> each memory region description in the consistent style.
>
> Secondly take the KASLR words out of the mm layout tables to make
> it as a separate section to only list mm layout in non-KASLR case.
> Then add KASLR document at the end of mm.txt.
>
> Meanwhile update document about KERNEL_IMAGE_SIZE in
> arch/x86/include/asm/page_64_types.h .
>
> Baoquan He (3):
> x86/KASLR: Update document about KERNEL_IMAGE_SIZE
> x86/mm/doc: Clean up the memory region layout descriptions
> x86/doc/kaslr.txt: Create a separate part of document abourt KASLR at
> the end of file
>
> Documentation/x86/x86_64/mm.txt | 138 +++++++++++++++++++++++------------
> arch/x86/include/asm/page_64_types.h | 7 +-
> 2 files changed, 96 insertions(+), 49 deletions(-)
>
> --
> 2.13.6
>
^ permalink raw reply [flat|nested] 12+ messages in thread