Revert "[PATCH] uml: export symbols added by GCC hardened"

This reverts commit cead61a6717a9873426b08d73a34a325e3546f5d.

It exported __stack_smash_handler and __guard, while they may not be
defined by anyone.

The code *declares* __stack_smash_handler and __guard. It does not
create weak symbols. If no external library is linked, they are left
undefined, but yet exported.

If a loadable module tries to access non-existing symbols, bad things
(a page fault, NULL pointer dereference, etc.) will happen. So, the
current code is wrong and dangerous.

If the code were written as follows, it would *define* them as weak
symbols so modules would be able to get access to them.

void (*__stack_smash_handler)(void *) __attribute__((weak));
EXPORT_SYMBOL(__stack_smash_handler);

long __guard __attribute__((weak));
EXPORT_SYMBOL(__guard);

In fact, modpost forbids exporting undefined symbols. It shows an error
message if it detects such a mistake.

ERROR: modpost: "..." [...] was exported without definition

Unfortunately, it is checked only when the code is built as modular.
The problem described above has been unnoticed for a long time because
arch/um/os-Linux/user_syms.c is always built-in.

With a planned change in Kbuild, exporting undefined symbols will always
result in a build error instead of a run-time error. It is a good thing,
but we need to fix the breakage in advance.

One fix is to define weak symbols as shown above. An alternative is to
export them conditionally as follows:

#ifdef CONFIG_STACKPROTECTOR
extern void __stack_smash_handler(void *);
EXPORT_SYMBOL(__stack_smash_handler);

external long __guard;
EXPORT_SYMBOL(__guard);
#endif

This is what other architectures do; EXPORT_SYMBOL(__stack_chk_guard)
is guarded by #ifdef CONFIG_STACKPROTECTOR.

However, adding the #ifdef guard is not sensible because UML cannot
enable the stack-protector in the first place! (Please note UML does
not select HAVE_STACKPROTECTOR in Kconfig.)

So, the code is already broken (and unused) in multiple ways.

Just remove.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

um: further clean up user_syms

Make some cleanups, add and fix some comments and document
here that we shouldn't export (libc) symbols for "_user.c"
code, rather such should work like hostfs does now.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

um: don't export printf()

Since printf() cannot be used in kernel threads (it
uses too much stack space) don't export it for modules
either.

This should leave us exporting only things that are
absolutely critical (such as memset and friends) and
things that are injected by the compiler (stack guard
and similar.)

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

um: hostfs: define our own API boundary

Instead of exporting the set of functions provided by
glibc that are needed for hostfs_user.c, just build that
into the kernel image whenever hostfs is built, and then
export _those_ functions cleanly, to be independent of
the libc implementation.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

um: add __weak for exported functions

If the exported glibc functions don't exist, we get link
failures. Avoid that by adding __weak so they're allowed
to not exist.

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Richard Weinberger <richard@nod.at>

um: Enable FORTIFY_SOURCE

Enable FORTIFY_SOURCE so running Kunit tests can test fortified
functions.

Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: David Gow <davidgow@google.com>
Link: https://lore.kernel.org/r/20220210003224.773957-1-keescook@chromium.org

UML: add support for KASAN under x86_64

Make KASAN run on User Mode Linux on x86_64.

The UML-specific KASAN initializer uses mmap to map the ~16TB of shadow
memory to the location defined by KASAN_SHADOW_OFFSET. kasan_init()
utilizes constructors to initialize KASAN before main().

The location of the KASAN shadow memory, starting at
KASAN_SHADOW_OFFSET, can be configured using the KASAN_SHADOW_OFFSET
option. The default location of this offset is 0x100000000000, which
keeps it out-of-the-way even on UML setups with more "physical" memory.

For low-memory setups, 0x7fff8000 can be used instead, which fits in an
immediate and is therefore faster, as suggested by Dmitry Vyukov. There
is usually enough free space at this location; however, it is a config
option so that it can be easily changed if needed.

Note that, unlike KASAN on other architectures, vmalloc allocations
still use the shadow memory allocated upfront, rather than allocating
and free-ing it per-vmalloc allocation.

If another architecture chooses to go down the same path, we should
replace the checks for CONFIG_UML with something more generic, such
as:
- A CONFIG_KASAN_NO_SHADOW_ALLOC option, which architectures could set
- or, a way of having architecture-specific versions of these vmalloc
and module shadow memory allocation options.

Also note that, while UML supports both KASAN in inline mode
(CONFIG_KASAN_INLINE) and static linking (CONFIG_STATIC_LINK), it does
not support both at the same time.

Signed-off-by: Patricia Alfonso <trishalfonso@google.com>
Co-developed-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

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>

um: get rid of pointless include "..." where include <...> will do

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>

um: use the right ifdef around exports in user_syms.c

... the same one that controls whether elf_aux.o is included into the
build, bringing the vsyscall_e... into it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>

um: fix _FORTIFY_SOURCE=2 support for kernel modules

When UML is compiled with _FORTIFY_SOURCE we have to export all _chk()
functions which are used in modules. For now it's only the case for
__sprintf_chk().

Tested-by: Florian Fainelli <florian@openwrt.org>
Reported-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Richard Weinberger <richard@nod.at>
Acked-by: Vitaliy Ivanov <vitalivanov@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Deal with missing exports for hostfs

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

uml: fix WARNING: vmlinux: 'memcpy' exported twice

Fix the following warning on x86_64:

LD vmlinux.o
MODPOST vmlinux.o
WARNING: vmlinux: 'memcpy' exported twice. Previous export was in vmlinux

For x86_64, this symbol is already exported from arch/um/sys-x86_64/ksyms.c.

Reported-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
Tested-by: Boaz Harrosh <bharrosh@panasas.com>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

uml: style fixes in arch/um/os-Linux

Style changes under arch/um/os-Linux:
include trimming
CodingStyle fixes
some printks needed severity indicators

make_tempfile turns out not to be used outside of mem.c, so it is now static.
Its declaration in tempfile.h is no longer needed, and tempfile.h itself is no
longer needed.

create_tmp_file was also made static.

checkpatch moans about an EXPORT_SYMBOL in user_syms.c which is part of a
macro definition - this is copying a bit of kernel infrastructure into the
libc side of UML because the kernel headers can't be included there.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

uml: fix string exporting on UML/i386

In 2.6.23-rc1, i386 fiddled its string support such that UML started getting
undefined references from modules. The UML asm/string.h was including the
i386 string.h, which defined __HAVE_ARCH_STR*, but the corresponding
implementations weren't being pulled in.

This is fixed by adding arch/i386/lib/string.h to the list of host
architecture files to be pulled in to UML.

A complication is that the libc exports file assumed that the generic strlen
and strstr weren't in use (i.e. __HAVE_ARCH_STR is defined), then they aren't
exported. This is untrue for strlen, which is exported in either case, so
this logic is not needed.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

uml: export hostfs symbols

Add some exports for hostfs that are required after Alberto Bertogli's fixes
for accessing unlinked host files.

Also did some style cleanups while I was here.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] uml: export symbols added by GCC hardened

GCC hardened introduces additional symbol refererences (for the canary and
friends), also in modules - add weak export_symbols for them. We already
tested that the weak declaration creates no problem on both GCC's providing
the function definition and on GCC's which don't provide it.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Acked-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] uml: fix some double export warnings

Some functions are exported twice in current code - remove the excess export.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] Hostfs: update for new glibc - add missing symbol exports

Today, when compiling UML, I got warnings for two used unexported symbols:
readdir64 and truncate64. Indeed, my glibc headers are aliasing readdir to
readdir64 and truncate to truncate64 (and so on).

I'm then adding additional exports. Since I've no idea if the symbols where
always provided in the supported glibc's, I've added weak definitions too.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] uml: implement hostfs syncing

Actually implement the hostfs "sync" method.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!