x86/efistub: Remap kernel text read-only before dropping NX attribute

Currently, the EFI stub invokes the EFI memory attributes protocol to
strip any NX restrictions from the entire loaded kernel, resulting in
all code and data being mapped read-write-execute.

The point of the EFI memory attributes protocol is to remove the need
for all memory allocations to be mapped with both write and execute
permissions by default, and make it the OS loader's responsibility to
transition data mappings to code mappings where appropriate.

Even though the UEFI specification does not appear to leave room for
denying memory attribute changes based on security policy, let's be
cautious and avoid relying on the ability to create read-write-execute
mappings. This is trivially achievable, given that the amount of kernel
code executing via the firmware's 1:1 mapping is rather small and
limited to the .head.text region. So let's drop the NX restrictions only
on that subregion, but not before remapping it as read-only first.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

x86/boot: Rename conflicting 'boot_params' pointer to 'boot_params_ptr'

The x86 decompressor is built and linked as a separate executable, but
it shares components with the kernel proper, which are either #include'd
as C files, or linked into the decompresor as a static library (e.g, the
EFI stub)

Both the kernel itself and the decompressor define a global symbol
'boot_params' to refer to the boot_params struct, but in the former
case, it refers to the struct directly, whereas in the decompressor, it
refers to a global pointer variable referring to the struct boot_params
passed by the bootloader or constructed from scratch.

This ambiguity is unfortunate, and makes it impossible to assign this
decompressor variable from the x86 EFI stub, given that declaring it as
extern results in a clash. So rename the decompressor version (whose
scope is limited) to boot_params_ptr.

[ mingo: Renamed 'boot_params_p' to 'boot_params_ptr' for clarity ]

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org

x86/boot/compressed: Reserve more memory for page tables

The decompressor has a hard limit on the number of page tables it can
allocate. This limit is defined at compile-time and will cause boot
failure if it is reached.

The kernel is very strict and calculates the limit precisely for the
worst-case scenario based on the current configuration. However, it is
easy to forget to adjust the limit when a new use-case arises. The
worst-case scenario is rarely encountered during sanity checks.

In the case of enabling 5-level paging, a use-case was overlooked. The
limit needs to be increased by one to accommodate the additional level.
This oversight went unnoticed until Aaron attempted to run the kernel
via kexec with 5-level paging and unaccepted memory enabled.

Update wost-case calculations to include 5-level paging.

To address this issue, let's allocate some extra space for page tables.
128K should be sufficient for any use-case. The logic can be simplified
by using a single value for all kernel configurations.

[ Also add a warning, should this memory run low - by Dave Hansen. ]

Fixes: 34bbb0009f3b ("x86/boot/compressed: Enable 5-level paging during decompression stage")
Reported-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230915070221.10266-1-kirill.shutemov@linux.intel.com

x86/decompressor: Factor out kernel decompression and relocation

Factor out the decompressor sequence that invokes the decompressor,
parses the ELF and applies the relocations so that it can be called
directly from the EFI stub.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230807162720.545787-21-ardb@kernel.org

x86: Add support for ZSTD compressed kernel

- Add support for zstd compressed kernel

- Define __DISABLE_EXPORTS in Makefile

- Remove __DISABLE_EXPORTS definition from kaslr.c

- Bump the heap size for zstd.

- Update the documentation.

Integrates the ZSTD decompression code to the x86 pre-boot code.

Zstandard requires slightly more memory during the kernel decompression
on x86 (192 KB vs 64 KB), and the memory usage is independent of the
window size.

__DISABLE_EXPORTS is now defined in the Makefile, which covers both
the existing use in kaslr.c, and the use needed by the zstd decompressor
in misc.c.

This patch has been boot tested with both a zstd and gzip compressed
kernel on i386 and x86_64 using buildroot and QEMU.

Additionally, this has been tested in production on x86_64 devices.
We saw a 2 second boot time reduction by switching kernel compression
from xz to zstd.

Signed-off-by: Nick Terrell <terrelln@fb.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20200730190841.2071656-7-nickrterrell@gmail.com

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

x86/KASLR: Build identity mappings on demand

Currently KASLR only supports relocation in a small physical range (from
16M to 1G), due to using the initial kernel page table identity mapping.
To support ranges above this, we need to have an identity mapping for the
desired memory range before we can decompress (and later run) the kernel.

32-bit kernels already have the needed identity mapping. This patch adds
identity mappings for the needed memory ranges on 64-bit kernels. This
happens in two possible boot paths:

If loaded via startup_32(), we need to set up the needed identity map.

If loaded from a 64-bit bootloader, the bootloader will have already
set up an identity mapping, and we'll start via the compressed kernel's
startup_64(). In this case, the bootloader's page tables need to be
avoided while selecting the new uncompressed kernel location. If not,
the decompressor could overwrite them during decompression.

To accomplish this, we could walk the pagetable and find every page
that is used, and add them to mem_avoid, but this needs extra code and
will require increasing the size of the mem_avoid array.

Instead, we can create a new set of page tables for our own identity
mapping instead. The pages for the new page table will come from the
_pagetable section of the compressed kernel, which means they are
already contained by in mem_avoid array. To do this, we reuse the code
from the uncompressed kernel's identity mapping routines.

The _pgtable will be shared by both the 32-bit and 64-bit paths to reduce
init_size, as now the compressed kernel's _rodata to _end will contribute
to init_size.

To handle the possible mappings, we need to increase the existing page
table buffer size:

When booting via startup_64(), we need to cover the old VO, params,
cmdline and uncompressed kernel. In an extreme case we could have them
all beyond the 512G boundary, which needs (2+2)*4 pages with 2M mappings.
And we'll need 2 for first 2M for VGA RAM. One more is needed for level4.
This gets us to 19 pages total.

When booting via startup_32(), KASLR could move the uncompressed kernel
above 4G, so we need to create extra identity mappings, which should only
need (2+2) pages at most when it is beyond the 512G boundary. So 19
pages is sufficient for this case as well.

The resulting BOOT_*PGT_SIZE defines use the "_SIZE" suffix on their
names to maintain logical consistency with the existing BOOT_HEAP_SIZE
and BOOT_STACK_SIZE defines.

This patch is based on earlier patches from Yinghai Lu and Baoquan He.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: kernel-hardening@lists.openwall.com
Cc: lasse.collin@tukaani.org
Link: http://lkml.kernel.org/r/1462572095-11754-4-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

x86/boot: Clean up indenting for asm/boot.h

Before adding more defines to asm/boot.h, this cleans up the existing
indenting for readability.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: kernel-hardening@lists.openwall.com
Cc: lasse.collin@tukaani.org
Link: http://lkml.kernel.org/r/1462572095-11754-2-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

x86/boot: Double BOOT_HEAP_SIZE to 64KB

When decompressing kernel image during x86 bootup, malloc memory
for ELF program headers may run out of heap space, which leads
to system halt. This patch doubles BOOT_HEAP_SIZE to 64KB.

Tested with 32-bit kernel which failed to boot without this patch.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: <stable@vger.kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

UAPI: (Scripted) Disintegrate arch/x86/include/asm

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>

x86: Use common threadinfo allocator

The only difference is the free_thread_info function, which frees
xstate.

Use the new arch_release_task_struct() function instead and switch
over to the core allocator.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20120505150141.559556763@linutronix.de
Cc: x86@kernel.org

x86: support XZ-compressed kernel

This integrates the XZ decompression code to the x86 pre-boot code.

mkpiggy.c is updated to reserve about 32 KiB more buffer safety margin for
kernel decompression. It is done unconditionally for all decompressors to
keep the code simpler.

The XZ decompressor needs around 30 KiB of heap, so the heap size is
increased to 32 KiB on both x86-32 and x86-64.

Documentation/x86/boot.txt is updated to list the XZ magic number.

With the x86 BCJ filter in XZ, XZ-compressed x86 kernel tends to be a few
percent smaller than the equivalent LZMA-compressed kernel.

Signed-off-by: Lasse Collin <lasse.collin@tukaani.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alain Knaff <alain@knaff.lu>
Cc: Albin Tonnerre <albin.tonnerre@free-electrons.com>
Cc: Phillip Lougher <phillip@lougher.demon.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

x86: Clean up arch/x86/Kconfig*

No functional change intended.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <4BCF2690020000780003B340@vpn.id2.novell.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

x86, setup: correct include file in <asm/boot.h>

<asm/boot.h> needs <asm/pgtable_types.h>, not <asm/page_types.h> in
order to resolve PMD_SHIFT. Also, correct a +1 which really should be
+ THREAD_ORDER.

This is a build error which was masked by a typoed #ifdef.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

x86, setup: Fix typo "CONFIG_x86_64" in <asm/boot.h>

CONFIG_X86_64 was misspelled (wrong case), which caused the x86-64
kernel to advertise itself as more relocatable than it really is.
This could in theory cause boot failures once bootloaders start
support the new relocation fields.

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

x86, boot: make kernel_alignment adjustable; new bzImage fields

Make the kernel_alignment field adjustable; this allows us to set it
to a large value (intended to be 16 MB to avoid ZONE_DMA contention,
memory holes and other weirdness) while a smart bootloader can still
force a loading at a lesser alignment if absolutely necessary.

Also export pref_address (preferred loading address, corresponding to
the link-time address) and init_size, the total amount of linear
memory the kernel will require during initialization.

[ Impact: allows better kernel placement, gives bootloader more info ]

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

x86: remove zImage support

Impact: obsolete feature removal

The zImage kernel format has been functionally unused for a very long
time. It is just barely possible to build a modern kernel that still
fits within the zImage size limit, but it is highly unlikely that
anyone ever uses it. Furthermore, although it is still supported by
most bootloaders, it has been at best poorly tested (or not tested at
all); some bootloaders are even known to not support zImage at all and
not having even noticed.

Also remove some really obsolete constants that no longer have any
meaning.

LKML-Reference: <49B703D4.1000008@zytor.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

x86: headers cleanup - boot.h

Impact: cleanup

'make headers_check' warn us about leaking of kernel private
(mostly compile time vars) data to userspace in headers. Fix it.

Neither BOOT_HEAP_SIZE, BOOT_STACK_SIZE refs
was found by searching thru net (ie in user-space area)
so fence this all by __KERNEL__ guard.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

bzip2/lzma: x86 kernel compression support

Impact: Replaces x86 kernel decompressor with new code

This is the third part of the bzip2/lzma patch

The bzip patch is based on an idea by Christian Ludwig, includes support for
compressing the kernel with bzip2 or lzma rather than gzip. Both
compressors give smaller sizes than gzip. Lzma's decompresses faster
than bzip2.

It also supports ramdisks and initramfs' compressed using these two
compressors.

The functionality has been successfully used for a couple of years by
the udpcast project

This version applies to "tip" kernel 2.6.28

This part contains:
- support for new bzip2 and lzma kernel compression for x86

Signed-off-by: Alain Knaff <alain@knaff.lu>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

x86: Fix ASM_X86__ header guards

Change header guards named "ASM_X86__*" to "_ASM_X86_*" since:

a. the double underscore is ugly and pointless.
b. no leading underscore violates namespace constraints.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

x86, um: ... and asm-x86 move

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>