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>
2017-11-01 14:07:57 +00:00
|
|
|
/* SPDX-License-Identifier: GPL-2.0 */
|
2005-04-16 22:20:36 +00:00
|
|
|
#ifndef _LINUX_MMAN_H
|
|
|
|
|
#define _LINUX_MMAN_H
|
|
|
|
|
|
2006-04-25 13:18:07 +00:00
|
|
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#include <linux/mm.h>
|
2009-04-30 22:08:51 +00:00
|
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|
#include <linux/percpu_counter.h>
|
2006-04-25 13:18:07 +00:00
|
|
|
|
2011-07-26 23:09:06 +00:00
|
|
|
#include <linux/atomic.h>
|
2012-10-13 09:46:48 +00:00
|
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|
#include <uapi/linux/mman.h>
|
2006-04-25 13:18:07 +00:00
|
|
|
|
mm: introduce MAP_SHARED_VALIDATE, a mechanism to safely define new mmap flags
The mmap(2) syscall suffers from the ABI anti-pattern of not validating
unknown flags. However, proposals like MAP_SYNC need a mechanism to
define new behavior that is known to fail on older kernels without the
support. Define a new MAP_SHARED_VALIDATE flag pattern that is
guaranteed to fail on all legacy mmap implementations.
It is worth noting that the original proposal was for a standalone
MAP_VALIDATE flag. However, when that could not be supported by all
archs Linus observed:
I see why you *think* you want a bitmap. You think you want
a bitmap because you want to make MAP_VALIDATE be part of MAP_SYNC
etc, so that people can do
ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED
| MAP_SYNC, fd, 0);
and "know" that MAP_SYNC actually takes.
And I'm saying that whole wish is bogus. You're fundamentally
depending on special semantics, just make it explicit. It's already
not portable, so don't try to make it so.
Rename that MAP_VALIDATE as MAP_SHARED_VALIDATE, make it have a value
of 0x3, and make people do
ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED_VALIDATE
| MAP_SYNC, fd, 0);
and then the kernel side is easier too (none of that random garbage
playing games with looking at the "MAP_VALIDATE bit", but just another
case statement in that map type thing.
Boom. Done.
Similar to ->fallocate() we also want the ability to validate the
support for new flags on a per ->mmap() 'struct file_operations'
instance basis. Towards that end arrange for flags to be generically
validated against a mmap_supported_flags exported by 'struct
file_operations'. By default all existing flags are implicitly
supported, but new flags require MAP_SHARED_VALIDATE and
per-instance-opt-in.
Cc: Jan Kara <jack@suse.cz>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-11-01 15:36:30 +00:00
|
|
|
/*
|
|
|
|
|
* Arrange for legacy / undefined architecture specific flags to be
|
2017-11-01 15:36:41 +00:00
|
|
|
* ignored by mmap handling code.
|
mm: introduce MAP_SHARED_VALIDATE, a mechanism to safely define new mmap flags
The mmap(2) syscall suffers from the ABI anti-pattern of not validating
unknown flags. However, proposals like MAP_SYNC need a mechanism to
define new behavior that is known to fail on older kernels without the
support. Define a new MAP_SHARED_VALIDATE flag pattern that is
guaranteed to fail on all legacy mmap implementations.
It is worth noting that the original proposal was for a standalone
MAP_VALIDATE flag. However, when that could not be supported by all
archs Linus observed:
I see why you *think* you want a bitmap. You think you want
a bitmap because you want to make MAP_VALIDATE be part of MAP_SYNC
etc, so that people can do
ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED
| MAP_SYNC, fd, 0);
and "know" that MAP_SYNC actually takes.
And I'm saying that whole wish is bogus. You're fundamentally
depending on special semantics, just make it explicit. It's already
not portable, so don't try to make it so.
Rename that MAP_VALIDATE as MAP_SHARED_VALIDATE, make it have a value
of 0x3, and make people do
ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED_VALIDATE
| MAP_SYNC, fd, 0);
and then the kernel side is easier too (none of that random garbage
playing games with looking at the "MAP_VALIDATE bit", but just another
case statement in that map type thing.
Boom. Done.
Similar to ->fallocate() we also want the ability to validate the
support for new flags on a per ->mmap() 'struct file_operations'
instance basis. Towards that end arrange for flags to be generically
validated against a mmap_supported_flags exported by 'struct
file_operations'. By default all existing flags are implicitly
supported, but new flags require MAP_SHARED_VALIDATE and
per-instance-opt-in.
Cc: Jan Kara <jack@suse.cz>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-11-01 15:36:30 +00:00
|
|
|
*/
|
|
|
|
|
#ifndef MAP_32BIT
|
|
|
|
|
#define MAP_32BIT 0
|
|
|
|
|
#endif
|
x86/mm: Introduce MAP_ABOVE4G
The x86 Control-flow Enforcement Technology (CET) feature includes a new
type of memory called shadow stack. This shadow stack memory has some
unusual properties, which require some core mm changes to function
properly.
One of the properties is that the shadow stack pointer (SSP), which is a
CPU register that points to the shadow stack like the stack pointer points
to the stack, can't be pointing outside of the 32 bit address space when
the CPU is executing in 32 bit mode. It is desirable to prevent executing
in 32 bit mode when shadow stack is enabled because the kernel can't easily
support 32 bit signals.
On x86 it is possible to transition to 32 bit mode without any special
interaction with the kernel, by doing a "far call" to a 32 bit segment.
So the shadow stack implementation can use this address space behavior
as a feature, by enforcing that shadow stack memory is always mapped
outside of the 32 bit address space. This way userspace will trigger a
general protection fault which will in turn trigger a segfault if it
tries to transition to 32 bit mode with shadow stack enabled.
This provides a clean error generating border for the user if they try
attempt to do 32 bit mode shadow stack, rather than leave the kernel in a
half working state for userspace to be surprised by.
So to allow future shadow stack enabling patches to map shadow stacks
out of the 32 bit address space, introduce MAP_ABOVE4G. The behavior
is pretty much like MAP_32BIT, except that it has the opposite address
range. The are a few differences though.
If both MAP_32BIT and MAP_ABOVE4G are provided, the kernel will use the
MAP_ABOVE4G behavior. Like MAP_32BIT, MAP_ABOVE4G is ignored in a 32 bit
syscall.
Since the default search behavior is top down, the normal kaslr base can
be used for MAP_ABOVE4G. This is unlike MAP_32BIT which has to add its
own randomization in the bottom up case.
For MAP_32BIT, only the bottom up search path is used. For MAP_ABOVE4G
both are potentially valid, so both are used. In the bottomup search
path, the default behavior is already consistent with MAP_ABOVE4G since
mmap base should be above 4GB.
Without MAP_ABOVE4G, the shadow stack will already normally be above 4GB.
So without introducing MAP_ABOVE4G, trying to transition to 32 bit mode
with shadow stack enabled would usually segfault anyway. This is already
pretty decent guard rails. But the addition of MAP_ABOVE4G is some small
complexity spent to make it make it more complete.
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Tested-by: Pengfei Xu <pengfei.xu@intel.com>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/all/20230613001108.3040476-21-rick.p.edgecombe%40intel.com
2023-06-13 00:10:46 +00:00
|
|
|
#ifndef MAP_ABOVE4G
|
|
|
|
|
#define MAP_ABOVE4G 0
|
|
|
|
|
#endif
|
mm: introduce MAP_SHARED_VALIDATE, a mechanism to safely define new mmap flags
The mmap(2) syscall suffers from the ABI anti-pattern of not validating
unknown flags. However, proposals like MAP_SYNC need a mechanism to
define new behavior that is known to fail on older kernels without the
support. Define a new MAP_SHARED_VALIDATE flag pattern that is
guaranteed to fail on all legacy mmap implementations.
It is worth noting that the original proposal was for a standalone
MAP_VALIDATE flag. However, when that could not be supported by all
archs Linus observed:
I see why you *think* you want a bitmap. You think you want
a bitmap because you want to make MAP_VALIDATE be part of MAP_SYNC
etc, so that people can do
ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED
| MAP_SYNC, fd, 0);
and "know" that MAP_SYNC actually takes.
And I'm saying that whole wish is bogus. You're fundamentally
depending on special semantics, just make it explicit. It's already
not portable, so don't try to make it so.
Rename that MAP_VALIDATE as MAP_SHARED_VALIDATE, make it have a value
of 0x3, and make people do
ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED_VALIDATE
| MAP_SYNC, fd, 0);
and then the kernel side is easier too (none of that random garbage
playing games with looking at the "MAP_VALIDATE bit", but just another
case statement in that map type thing.
Boom. Done.
Similar to ->fallocate() we also want the ability to validate the
support for new flags on a per ->mmap() 'struct file_operations'
instance basis. Towards that end arrange for flags to be generically
validated against a mmap_supported_flags exported by 'struct
file_operations'. By default all existing flags are implicitly
supported, but new flags require MAP_SHARED_VALIDATE and
per-instance-opt-in.
Cc: Jan Kara <jack@suse.cz>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-11-01 15:36:30 +00:00
|
|
|
#ifndef MAP_HUGE_2MB
|
|
|
|
|
#define MAP_HUGE_2MB 0
|
|
|
|
|
#endif
|
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|
#ifndef MAP_HUGE_1GB
|
|
|
|
|
#define MAP_HUGE_1GB 0
|
|
|
|
|
#endif
|
|
|
|
|
#ifndef MAP_UNINITIALIZED
|
|
|
|
|
#define MAP_UNINITIALIZED 0
|
|
|
|
|
#endif
|
2017-11-01 15:36:41 +00:00
|
|
|
#ifndef MAP_SYNC
|
|
|
|
|
#define MAP_SYNC 0
|
|
|
|
|
#endif
|
mm: introduce MAP_SHARED_VALIDATE, a mechanism to safely define new mmap flags
The mmap(2) syscall suffers from the ABI anti-pattern of not validating
unknown flags. However, proposals like MAP_SYNC need a mechanism to
define new behavior that is known to fail on older kernels without the
support. Define a new MAP_SHARED_VALIDATE flag pattern that is
guaranteed to fail on all legacy mmap implementations.
It is worth noting that the original proposal was for a standalone
MAP_VALIDATE flag. However, when that could not be supported by all
archs Linus observed:
I see why you *think* you want a bitmap. You think you want
a bitmap because you want to make MAP_VALIDATE be part of MAP_SYNC
etc, so that people can do
ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED
| MAP_SYNC, fd, 0);
and "know" that MAP_SYNC actually takes.
And I'm saying that whole wish is bogus. You're fundamentally
depending on special semantics, just make it explicit. It's already
not portable, so don't try to make it so.
Rename that MAP_VALIDATE as MAP_SHARED_VALIDATE, make it have a value
of 0x3, and make people do
ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED_VALIDATE
| MAP_SYNC, fd, 0);
and then the kernel side is easier too (none of that random garbage
playing games with looking at the "MAP_VALIDATE bit", but just another
case statement in that map type thing.
Boom. Done.
Similar to ->fallocate() we also want the ability to validate the
support for new flags on a per ->mmap() 'struct file_operations'
instance basis. Towards that end arrange for flags to be generically
validated against a mmap_supported_flags exported by 'struct
file_operations'. By default all existing flags are implicitly
supported, but new flags require MAP_SHARED_VALIDATE and
per-instance-opt-in.
Cc: Jan Kara <jack@suse.cz>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-11-01 15:36:30 +00:00
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* The historical set of flags that all mmap implementations implicitly
|
|
|
|
|
* support when a ->mmap_validate() op is not provided in file_operations.
|
2021-06-29 02:38:35 +00:00
|
|
|
*
|
2021-04-23 07:38:14 +00:00
|
|
|
* MAP_EXECUTABLE and MAP_DENYWRITE are completely ignored throughout the
|
|
|
|
|
* kernel.
|
mm: introduce MAP_SHARED_VALIDATE, a mechanism to safely define new mmap flags
The mmap(2) syscall suffers from the ABI anti-pattern of not validating
unknown flags. However, proposals like MAP_SYNC need a mechanism to
define new behavior that is known to fail on older kernels without the
support. Define a new MAP_SHARED_VALIDATE flag pattern that is
guaranteed to fail on all legacy mmap implementations.
It is worth noting that the original proposal was for a standalone
MAP_VALIDATE flag. However, when that could not be supported by all
archs Linus observed:
I see why you *think* you want a bitmap. You think you want
a bitmap because you want to make MAP_VALIDATE be part of MAP_SYNC
etc, so that people can do
ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED
| MAP_SYNC, fd, 0);
and "know" that MAP_SYNC actually takes.
And I'm saying that whole wish is bogus. You're fundamentally
depending on special semantics, just make it explicit. It's already
not portable, so don't try to make it so.
Rename that MAP_VALIDATE as MAP_SHARED_VALIDATE, make it have a value
of 0x3, and make people do
ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED_VALIDATE
| MAP_SYNC, fd, 0);
and then the kernel side is easier too (none of that random garbage
playing games with looking at the "MAP_VALIDATE bit", but just another
case statement in that map type thing.
Boom. Done.
Similar to ->fallocate() we also want the ability to validate the
support for new flags on a per ->mmap() 'struct file_operations'
instance basis. Towards that end arrange for flags to be generically
validated against a mmap_supported_flags exported by 'struct
file_operations'. By default all existing flags are implicitly
supported, but new flags require MAP_SHARED_VALIDATE and
per-instance-opt-in.
Cc: Jan Kara <jack@suse.cz>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-11-01 15:36:30 +00:00
|
|
|
*/
|
|
|
|
|
#define LEGACY_MAP_MASK (MAP_SHARED \
|
|
|
|
|
| MAP_PRIVATE \
|
|
|
|
|
| MAP_FIXED \
|
|
|
|
|
| MAP_ANONYMOUS \
|
|
|
|
|
| MAP_DENYWRITE \
|
|
|
|
|
| MAP_EXECUTABLE \
|
|
|
|
|
| MAP_UNINITIALIZED \
|
|
|
|
|
| MAP_GROWSDOWN \
|
|
|
|
|
| MAP_LOCKED \
|
|
|
|
|
| MAP_NORESERVE \
|
|
|
|
|
| MAP_POPULATE \
|
|
|
|
|
| MAP_NONBLOCK \
|
|
|
|
|
| MAP_STACK \
|
|
|
|
|
| MAP_HUGETLB \
|
|
|
|
|
| MAP_32BIT \
|
x86/mm: Introduce MAP_ABOVE4G
The x86 Control-flow Enforcement Technology (CET) feature includes a new
type of memory called shadow stack. This shadow stack memory has some
unusual properties, which require some core mm changes to function
properly.
One of the properties is that the shadow stack pointer (SSP), which is a
CPU register that points to the shadow stack like the stack pointer points
to the stack, can't be pointing outside of the 32 bit address space when
the CPU is executing in 32 bit mode. It is desirable to prevent executing
in 32 bit mode when shadow stack is enabled because the kernel can't easily
support 32 bit signals.
On x86 it is possible to transition to 32 bit mode without any special
interaction with the kernel, by doing a "far call" to a 32 bit segment.
So the shadow stack implementation can use this address space behavior
as a feature, by enforcing that shadow stack memory is always mapped
outside of the 32 bit address space. This way userspace will trigger a
general protection fault which will in turn trigger a segfault if it
tries to transition to 32 bit mode with shadow stack enabled.
This provides a clean error generating border for the user if they try
attempt to do 32 bit mode shadow stack, rather than leave the kernel in a
half working state for userspace to be surprised by.
So to allow future shadow stack enabling patches to map shadow stacks
out of the 32 bit address space, introduce MAP_ABOVE4G. The behavior
is pretty much like MAP_32BIT, except that it has the opposite address
range. The are a few differences though.
If both MAP_32BIT and MAP_ABOVE4G are provided, the kernel will use the
MAP_ABOVE4G behavior. Like MAP_32BIT, MAP_ABOVE4G is ignored in a 32 bit
syscall.
Since the default search behavior is top down, the normal kaslr base can
be used for MAP_ABOVE4G. This is unlike MAP_32BIT which has to add its
own randomization in the bottom up case.
For MAP_32BIT, only the bottom up search path is used. For MAP_ABOVE4G
both are potentially valid, so both are used. In the bottomup search
path, the default behavior is already consistent with MAP_ABOVE4G since
mmap base should be above 4GB.
Without MAP_ABOVE4G, the shadow stack will already normally be above 4GB.
So without introducing MAP_ABOVE4G, trying to transition to 32 bit mode
with shadow stack enabled would usually segfault anyway. This is already
pretty decent guard rails. But the addition of MAP_ABOVE4G is some small
complexity spent to make it make it more complete.
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Tested-by: Pengfei Xu <pengfei.xu@intel.com>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/all/20230613001108.3040476-21-rick.p.edgecombe%40intel.com
2023-06-13 00:10:46 +00:00
|
|
|
| MAP_ABOVE4G \
|
mm: introduce MAP_SHARED_VALIDATE, a mechanism to safely define new mmap flags
The mmap(2) syscall suffers from the ABI anti-pattern of not validating
unknown flags. However, proposals like MAP_SYNC need a mechanism to
define new behavior that is known to fail on older kernels without the
support. Define a new MAP_SHARED_VALIDATE flag pattern that is
guaranteed to fail on all legacy mmap implementations.
It is worth noting that the original proposal was for a standalone
MAP_VALIDATE flag. However, when that could not be supported by all
archs Linus observed:
I see why you *think* you want a bitmap. You think you want
a bitmap because you want to make MAP_VALIDATE be part of MAP_SYNC
etc, so that people can do
ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED
| MAP_SYNC, fd, 0);
and "know" that MAP_SYNC actually takes.
And I'm saying that whole wish is bogus. You're fundamentally
depending on special semantics, just make it explicit. It's already
not portable, so don't try to make it so.
Rename that MAP_VALIDATE as MAP_SHARED_VALIDATE, make it have a value
of 0x3, and make people do
ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED_VALIDATE
| MAP_SYNC, fd, 0);
and then the kernel side is easier too (none of that random garbage
playing games with looking at the "MAP_VALIDATE bit", but just another
case statement in that map type thing.
Boom. Done.
Similar to ->fallocate() we also want the ability to validate the
support for new flags on a per ->mmap() 'struct file_operations'
instance basis. Towards that end arrange for flags to be generically
validated against a mmap_supported_flags exported by 'struct
file_operations'. By default all existing flags are implicitly
supported, but new flags require MAP_SHARED_VALIDATE and
per-instance-opt-in.
Cc: Jan Kara <jack@suse.cz>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-11-01 15:36:30 +00:00
|
|
|
| MAP_HUGE_2MB \
|
|
|
|
|
| MAP_HUGE_1GB)
|
|
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
extern int sysctl_overcommit_memory;
|
|
|
|
|
extern int sysctl_overcommit_ratio;
|
2014-01-21 23:49:14 +00:00
|
|
|
extern unsigned long sysctl_overcommit_kbytes;
|
2009-04-30 22:08:51 +00:00
|
|
|
extern struct percpu_counter vm_committed_as;
|
2005-04-16 22:20:36 +00:00
|
|
|
|
2013-07-03 22:02:44 +00:00
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
|
extern s32 vm_committed_as_batch;
|
2020-08-07 06:23:15 +00:00
|
|
|
extern void mm_compute_batch(int overcommit_policy);
|
2013-07-03 22:02:44 +00:00
|
|
|
#else
|
|
|
|
|
#define vm_committed_as_batch 0
|
2020-08-07 06:23:15 +00:00
|
|
|
static inline void mm_compute_batch(int overcommit_policy)
|
|
|
|
|
{
|
|
|
|
|
}
|
2013-07-03 22:02:44 +00:00
|
|
|
#endif
|
|
|
|
|
|
2012-11-15 22:34:42 +00:00
|
|
|
unsigned long vm_memory_committed(void);
|
|
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
static inline void vm_acct_memory(long pages)
|
|
|
|
|
{
|
2017-06-20 18:01:20 +00:00
|
|
|
percpu_counter_add_batch(&vm_committed_as, pages, vm_committed_as_batch);
|
2005-04-16 22:20:36 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static inline void vm_unacct_memory(long pages)
|
|
|
|
|
{
|
|
|
|
|
vm_acct_memory(-pages);
|
|
|
|
|
}
|
|
|
|
|
|
2008-07-07 14:28:51 +00:00
|
|
|
/*
|
2019-11-25 17:27:06 +00:00
|
|
|
* Allow architectures to handle additional protection and flag bits. The
|
|
|
|
|
* overriding macros must be defined in the arch-specific asm/mman.h file.
|
2008-07-07 14:28:51 +00:00
|
|
|
*/
|
|
|
|
|
|
|
|
|
|
#ifndef arch_calc_vm_prot_bits
|
2016-02-12 21:02:31 +00:00
|
|
|
#define arch_calc_vm_prot_bits(prot, pkey) 0
|
2008-07-07 14:28:51 +00:00
|
|
|
#endif
|
|
|
|
|
|
2019-11-25 17:27:06 +00:00
|
|
|
#ifndef arch_calc_vm_flag_bits
|
|
|
|
|
#define arch_calc_vm_flag_bits(flags) 0
|
|
|
|
|
#endif
|
|
|
|
|
|
2008-07-07 14:28:51 +00:00
|
|
|
#ifndef arch_validate_prot
|
|
|
|
|
/*
|
|
|
|
|
* This is called from mprotect(). PROT_GROWSDOWN and PROT_GROWSUP have
|
|
|
|
|
* already been masked out.
|
|
|
|
|
*
|
|
|
|
|
* Returns true if the prot flags are valid
|
|
|
|
|
*/
|
2018-02-21 17:15:49 +00:00
|
|
|
static inline bool arch_validate_prot(unsigned long prot, unsigned long addr)
|
2008-07-07 14:28:51 +00:00
|
|
|
{
|
|
|
|
|
return (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM)) == 0;
|
|
|
|
|
}
|
|
|
|
|
#define arch_validate_prot arch_validate_prot
|
|
|
|
|
#endif
|
|
|
|
|
|
2019-11-25 17:27:06 +00:00
|
|
|
#ifndef arch_validate_flags
|
|
|
|
|
/*
|
|
|
|
|
* This is called from mmap() and mprotect() with the updated vma->vm_flags.
|
|
|
|
|
*
|
|
|
|
|
* Returns true if the VM_* flags are valid.
|
|
|
|
|
*/
|
|
|
|
|
static inline bool arch_validate_flags(unsigned long flags)
|
|
|
|
|
{
|
|
|
|
|
return true;
|
|
|
|
|
}
|
|
|
|
|
#define arch_validate_flags arch_validate_flags
|
|
|
|
|
#endif
|
|
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
/*
|
|
|
|
|
* Optimisation macro. It is equivalent to:
|
|
|
|
|
* (x & bit1) ? bit2 : 0
|
|
|
|
|
* but this version is faster.
|
|
|
|
|
* ("bit1" and "bit2" must be single bits)
|
|
|
|
|
*/
|
|
|
|
|
#define _calc_vm_trans(x, bit1, bit2) \
|
2017-11-03 11:21:21 +00:00
|
|
|
((!(bit1) || !(bit2)) ? 0 : \
|
2005-04-16 22:20:36 +00:00
|
|
|
((bit1) <= (bit2) ? ((x) & (bit1)) * ((bit2) / (bit1)) \
|
2017-11-03 11:21:21 +00:00
|
|
|
: ((x) & (bit1)) / ((bit1) / (bit2))))
|
2005-04-16 22:20:36 +00:00
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Combine the mmap "prot" argument into "vm_flags" used internally.
|
|
|
|
|
*/
|
|
|
|
|
static inline unsigned long
|
2016-02-12 21:02:31 +00:00
|
|
|
calc_vm_prot_bits(unsigned long prot, unsigned long pkey)
|
2005-04-16 22:20:36 +00:00
|
|
|
{
|
|
|
|
|
return _calc_vm_trans(prot, PROT_READ, VM_READ ) |
|
|
|
|
|
_calc_vm_trans(prot, PROT_WRITE, VM_WRITE) |
|
2008-07-07 14:28:51 +00:00
|
|
|
_calc_vm_trans(prot, PROT_EXEC, VM_EXEC) |
|
2016-02-12 21:02:31 +00:00
|
|
|
arch_calc_vm_prot_bits(prot, pkey);
|
2005-04-16 22:20:36 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Combine the mmap "flags" argument into "vm_flags" used internally.
|
|
|
|
|
*/
|
|
|
|
|
static inline unsigned long
|
|
|
|
|
calc_vm_flag_bits(unsigned long flags)
|
|
|
|
|
{
|
|
|
|
|
return _calc_vm_trans(flags, MAP_GROWSDOWN, VM_GROWSDOWN ) |
|
2017-11-01 15:36:41 +00:00
|
|
|
_calc_vm_trans(flags, MAP_LOCKED, VM_LOCKED ) |
|
2019-11-25 17:27:06 +00:00
|
|
|
_calc_vm_trans(flags, MAP_SYNC, VM_SYNC ) |
|
|
|
|
|
arch_calc_vm_flag_bits(flags);
|
2005-04-16 22:20:36 +00:00
|
|
|
}
|
2013-11-12 23:08:31 +00:00
|
|
|
|
|
|
|
|
unsigned long vm_commit_limit(void);
|
mm: implement memory-deny-write-execute as a prctl
Patch series "mm: In-kernel support for memory-deny-write-execute (MDWE)",
v2.
The background to this is that systemd has a configuration option called
MemoryDenyWriteExecute [2], implemented as a SECCOMP BPF filter. Its aim
is to prevent a user task from inadvertently creating an executable
mapping that is (or was) writeable. Since such BPF filter is stateless,
it cannot detect mappings that were previously writeable but subsequently
changed to read-only. Therefore the filter simply rejects any
mprotect(PROT_EXEC). The side-effect is that on arm64 with BTI support
(Branch Target Identification), the dynamic loader cannot change an ELF
section from PROT_EXEC to PROT_EXEC|PROT_BTI using mprotect(). For
libraries, it can resort to unmapping and re-mapping but for the main
executable it does not have a file descriptor. The original bug report in
the Red Hat bugzilla - [3] - and subsequent glibc workaround for libraries
- [4].
This series adds in-kernel support for this feature as a prctl
PR_SET_MDWE, that is inherited on fork(). The prctl denies PROT_WRITE |
PROT_EXEC mappings. Like the systemd BPF filter it also denies adding
PROT_EXEC to mappings. However unlike the BPF filter it only denies it if
the mapping didn't previous have PROT_EXEC. This allows to PROT_EXEC ->
PROT_EXEC | PROT_BTI with mprotect(), which is a problem with the BPF
filter.
This patch (of 2):
The aim of such policy is to prevent a user task from creating an
executable mapping that is also writeable.
An example of mmap() returning -EACCESS if the policy is enabled:
mmap(0, size, PROT_READ | PROT_WRITE | PROT_EXEC, flags, 0, 0);
Similarly, mprotect() would return -EACCESS below:
addr = mmap(0, size, PROT_READ | PROT_EXEC, flags, 0, 0);
mprotect(addr, size, PROT_READ | PROT_WRITE | PROT_EXEC);
The BPF filter that systemd MDWE uses is stateless, and disallows
mprotect() with PROT_EXEC completely. This new prctl allows PROT_EXEC to
be enabled if it was already PROT_EXEC, which allows the following case:
addr = mmap(0, size, PROT_READ | PROT_EXEC, flags, 0, 0);
mprotect(addr, size, PROT_READ | PROT_EXEC | PROT_BTI);
where PROT_BTI enables branch tracking identification on arm64.
Link: https://lkml.kernel.org/r/20230119160344.54358-1-joey.gouly@arm.com
Link: https://lkml.kernel.org/r/20230119160344.54358-2-joey.gouly@arm.com
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Co-developed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jeremy Linton <jeremy.linton@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Mark Brown <broonie@kernel.org>
Cc: nd <nd@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Szabolcs Nagy <szabolcs.nagy@arm.com>
Cc: Topi Miettinen <toiwoton@gmail.com>
Cc: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-19 16:03:43 +00:00
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Denies creating a writable executable mapping or gaining executable permissions.
|
|
|
|
|
*
|
|
|
|
|
* This denies the following:
|
|
|
|
|
*
|
|
|
|
|
* a) mmap(PROT_WRITE | PROT_EXEC)
|
|
|
|
|
*
|
|
|
|
|
* b) mmap(PROT_WRITE)
|
|
|
|
|
* mprotect(PROT_EXEC)
|
|
|
|
|
*
|
|
|
|
|
* c) mmap(PROT_WRITE)
|
|
|
|
|
* mprotect(PROT_READ)
|
|
|
|
|
* mprotect(PROT_EXEC)
|
|
|
|
|
*
|
|
|
|
|
* But allows the following:
|
|
|
|
|
*
|
|
|
|
|
* d) mmap(PROT_READ | PROT_EXEC)
|
|
|
|
|
* mmap(PROT_READ | PROT_EXEC | PROT_BTI)
|
|
|
|
|
*/
|
|
|
|
|
static inline bool map_deny_write_exec(struct vm_area_struct *vma, unsigned long vm_flags)
|
|
|
|
|
{
|
|
|
|
|
if (!test_bit(MMF_HAS_MDWE, ¤t->mm->flags))
|
|
|
|
|
return false;
|
|
|
|
|
|
|
|
|
|
if ((vm_flags & VM_EXEC) && (vm_flags & VM_WRITE))
|
|
|
|
|
return true;
|
|
|
|
|
|
|
|
|
|
if (!(vma->vm_flags & VM_EXEC) && (vm_flags & VM_EXEC))
|
|
|
|
|
return true;
|
|
|
|
|
|
|
|
|
|
return false;
|
|
|
|
|
}
|
|
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
#endif /* _LINUX_MMAN_H */
|