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git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull hardening fixes from Kees Cook:
- randstruct: gcc-plugin: Fix attribute addition with GCC 15
- ubsan: integer-overflow: depend on BROKEN to keep this out of CI
- overflow: Introduce __DEFINE_FLEX for having no initializer
- wifi: iwlwifi: mld: Work around Clang loop unrolling bug
[ Take two after a jump scare due to some repo rewriting by 'b4' - Linus ]
* tag 'hardening-v6.16-rc1-fix1-take2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
randstruct: gcc-plugin: Fix attribute addition
overflow: Introduce __DEFINE_FLEX for having no initializer
ubsan: integer-overflow: depend on BROKEN to keep this out of CI
wifi: iwlwifi: mld: Work around Clang loop unrolling bug
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Based on changes in the 2021 public version of the randstruct
out-of-tree GCC plugin[1], more carefully update the attributes on
resulting decls, to avoid tripping checks in GCC 15's
comptypes_check_enum_int() when it has been configured with
"--enable-checking=misc":
arch/arm64/kernel/kexec_image.c:132:14: internal compiler error: in comptypes_check_enum_int, at c/c-typeck.cc:1519
132 | const struct kexec_file_ops kexec_image_ops = {
| ^~~~~~~~~~~~~~
internal_error(char const*, ...), at gcc/gcc/diagnostic-global-context.cc:517
fancy_abort(char const*, int, char const*), at gcc/gcc/diagnostic.cc:1803
comptypes_check_enum_int(tree_node*, tree_node*, bool*), at gcc/gcc/c/c-typeck.cc:1519
...
Link: https://archive.org/download/grsecurity/grsecurity-3.1-5.10.41-202105280954.patch.gz [1]
Reported-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Closes: https://github.com/KSPP/linux/issues/367
Closes: https://lore.kernel.org/lkml/20250530000646.104457-1-thiago.bauermann@linaro.org/
Reported-by: Ingo Saitz <ingo@hannover.ccc.de>
Closes: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1104745
Fixes: 313dd1b62921 ("gcc-plugins: Add the randstruct plugin")
Tested-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Link: https://lore.kernel.org/r/20250530221824.work.623-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic
Pull compiler version requirement update from Arnd Bergmann:
"Require gcc-8 and binutils-2.30
x86 already uses gcc-8 as the minimum version, this changes all other
architectures to the same version. gcc-8 is used is Debian 10 and Red
Hat Enterprise Linux 8, both of which are still supported, and
binutils 2.30 is the oldest corresponding version on those.
Ubuntu Pro 18.04 and SUSE Linux Enterprise Server 15 both use gcc-7 as
the system compiler but additionally include toolchains that remain
supported.
With the new minimum toolchain versions, a number of workarounds for
older versions can be dropped, in particular on x86_64 and arm64.
Importantly, the updated compiler version allows removing two of the
five remaining gcc plugins, as support for sancov and structeak
features is already included in modern compiler versions.
I tried collecting the known changes that are possible based on the
new toolchain version, but expect that more cleanups will be possible.
Since this touches multiple architectures, I merged the patches
through the asm-generic tree."
* tag 'gcc-minimum-version-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
Makefile.kcov: apply needed compiler option unconditionally in CFLAGS_KCOV
Documentation: update binutils-2.30 version reference
gcc-plugins: remove SANCOV gcc plugin
Kbuild: remove structleak gcc plugin
arm64: drop binutils version checks
raid6: skip avx512 checks
kbuild: require gcc-8 and binutils-2.30
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When building the randomized replacement tree of struct members, the
randstruct GCC plugin would insert, as the first member, a 0-sized void
member. This appears as though it was done to catch non-designated
("unnamed") static initializers, which wouldn't be stable since they
depend on the original struct layout order.
This was accomplished by having the side-effect of the "void member"
tripping an assert in GCC internals (count_type_elements) if the member
list ever needed to be counted (e.g. for figuring out the order of members
during a non-designated initialization), which would catch impossible type
(void) in the struct:
security/landlock/fs.c: In function ‘hook_file_ioctl_common’:
security/landlock/fs.c:1745:61: internal compiler error: in count_type_elements, at expr.cc:7075
1745 | .u.op = &(struct lsm_ioctlop_audit) {
| ^
static HOST_WIDE_INT
count_type_elements (const_tree type, bool for_ctor_p)
{
switch (TREE_CODE (type))
...
case VOID_TYPE:
default:
gcc_unreachable ();
}
}
However this is a redundant safety measure since randstruct uses the
__designated_initializer attribute both internally and within the
__randomized_layout attribute macro so that this would be enforced
by the compiler directly even when randstruct was not enabled (via
-Wdesignated-init).
A recent change in Landlock ended up tripping the same member counting
routine when using a full-struct copy initializer as part of an anonymous
initializer. This, however, is a false positive as the initializer is
copying between identical structs (and hence identical layouts). The
"path" member is "struct path", a randomized struct, and is being copied
to from another "struct path", the "f_path" member:
landlock_log_denial(landlock_cred(file->f_cred), &(struct landlock_request) {
.type = LANDLOCK_REQUEST_FS_ACCESS,
.audit = {
.type = LSM_AUDIT_DATA_IOCTL_OP,
.u.op = &(struct lsm_ioctlop_audit) {
.path = file->f_path,
.cmd = cmd,
},
},
...
As can be seen with the coming randstruct KUnit test, there appears to
be no behavioral problems with this kind of initialization when the void
member is removed from the randstruct GCC plugin, so remove it.
Reported-by: "Dr. David Alan Gilbert" <linux@treblig.org>
Closes: https://lore.kernel.org/lkml/Z_PRaKx7q70MKgCA@gallifrey/
Reported-by: Mark Brown <broonie@kernel.org>
Closes: https://lore.kernel.org/lkml/20250407-kbuild-disable-gcc-plugins-v1-1-5d46ae583f5e@kernel.org/
Reported-by: WangYuli <wangyuli@uniontech.com>
Closes: https://lore.kernel.org/lkml/337D5D4887277B27+3c677db3-a8b9-47f0-93a4-7809355f1381@uniontech.com/
Fixes: 313dd1b62921 ("gcc-plugins: Add the randstruct plugin")
Signed-off-by: Kees Cook <kees@kernel.org>
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There was no dependency between the plugins changing and the rest of the
kernel being built. This could cause strange behaviors as instrumentation
could vary between targets depending on when they were built.
Generate a new header file, gcc-plugins.h, any time the GCC plugins
change. Include the header file in compiler-version.h when its associated
feature name, GCC_PLUGINS, is defined. This will be picked up by fixdep
and force rebuilds where needed.
Add a generic "touch" kbuild command, which will be used again in
a following patch. Add a "normalize_path" string helper to make the
"TOUCH" output less ugly.
Link: https://lore.kernel.org/r/20250503184623.2572355-1-kees@kernel.org
Tested-by: Nicolas Schier <n.schier@avm.de>
Reviewed-by: Nicolas Schier <n.schier@avm.de>
Signed-off-by: Kees Cook <kees@kernel.org>
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With the minimum gcc version raised to 8.1, all supported compilers
now understand the -fsanitize-coverage=trace-pc option, and there
is no longer a need for the separate compiler plugin.
Since only gcc-5 was able to use the plugin for several year now,
it was already likely unused.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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gcc-12 and higher support the -ftrivial-auto-var-init= flag, after
gcc-8 is the minimum version, this is half of the supported ones, and
the vast majority of the versions that users are actually likely to
have, so it seems like a good time to stop having the fallback
plugin implementation
Older toolchains are still able to build kernels normally without
this plugin, but won't be able to use variable initialization..
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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Commit a3e8fe814ad1 ("x86/build: Raise the minimum GCC version to 8.1")
raised the minimum compiler version as enforced by Kbuild to gcc-8.1
and clang-15 for x86.
This is actually the same gcc version that has been discussed as the
minimum for all architectures several times in the past, with little
objection. A previous concern was the kernel for SLE15-SP7 needing to
be built with gcc-7. As this ended up still using linux-6.4 and there
is no plan for an SP8, this is no longer a problem.
Change it for all architectures and adjust the documentation accordingly.
A few version checks can be removed in the process. The binutils
version 2.30 is the lowest version used in combination with gcc-8 on
common distros, so use that as the corresponding minimum.
Link: https://lore.kernel.org/lkml/20240925150059.3955569-32-ardb+git@google.com/
Link: https://lore.kernel.org/lkml/871q7yxrgv.wl-tiwai@suse.de/
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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As part of trying to remove GCC plugins from Linux, drop the
ARM_SSP_PER_TASK plugin. The feature is available upstream since GCC
12, so anyone needing newer kernels with per-task ssp can update their
compiler[1].
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/all/08393aa3-05a3-4e3f-8004-f374a3ec4b7e@app.fastmail.com/ [1]
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250409160409.work.168-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
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Since the kernel currently requires GCC 5.1 as a minimum, remove the
unnecessary GCC version >= 4.7 check.
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Link: https://lore.kernel.org/r/20240723165332.1947-1-thorsten.blum@toblux.com
Signed-off-by: Kees Cook <kees@kernel.org>
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The header file stringpool.h is included for GCC version >= 8 and then
again for all versions.
Since the header file stringpool.h was added in GCC 4.9 and the kernel
currently requires GCC 5.1 as a minimum, remove the conditional include.
Including the header file only once removes the following warning
reported by make includecheck:
stringpool.h is included more than once
However, it's important to include stringpool.h before attribs.h
because attribs.h uses some of its functions.
Compile-tested with GCC 14.
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Link: https://lore.kernel.org/r/20240629233608.278028-2-thorsten.blum@toblux.com
Signed-off-by: Kees Cook <kees@kernel.org>
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The .head.text section carries the startup code that runs with the MMU
off or with a translation of memory that deviates from the ordinary one.
So avoid instrumentation with the stackleak plugin, which already avoids
.init.text and .noinstr.text entirely.
Fixes: 48204aba801f1b51 ("x86/sme: Move early SME kernel encryption handling into .head.text")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202403221630.2692c998-oliver.sang@intel.com
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240328064256.2358634-2-ardb+git@google.com
Signed-off-by: Kees Cook <keescook@chromium.org>
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Update code comment to clarify that the only element whose layout is
not randomized is a proper C99 flexible-array member. This update is
complementary to commit 1ee60356c2dc ("gcc-plugins: randstruct: Only
warn about true flexible arrays")
Signed-off-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/ZWJr2MWDjXLHE8ap@work
Fixes: 1ee60356c2dc ("gcc-plugins: randstruct: Only warn about true flexible arrays")
Signed-off-by: Kees Cook <keescook@chromium.org>
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Fix the typo in the plugin description comment. Clearly, "argc" should
be used.
Signed-off-by: Konstantin Runov <runebone1@gmail.com>
Link: https://lore.kernel.org/r/20231030094508.245432-1-runebone1@gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
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The randstruct GCC plugin tried to discover "fake" flexible arrays
to issue warnings about them in randomized structs. In the future
LSM overhead reduction series, it would be legal to have a randomized
struct with a 1-element array, and this should _not_ be treated as a
flexible array, especially since commit df8fc4e934c1 ("kbuild: Enable
-fstrict-flex-arrays=3"). Disable the 0-sized and 1-element array
discovery logic in the plugin, but keep the "true" flexible array check.
Cc: KP Singh <kpsingh@kernel.org>
Cc: linux-hardening@vger.kernel.org
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311021532.iBwuZUZ0-lkp@intel.com/
Fixes: df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3")
Reviewed-by: Bill Wendling <morbo@google.com>
Acked-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20231104204334.work.160-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
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The performance mode of the gcc-plugin randstruct was shuffling struct
members outside of the cache-line groups. Limit the range to the
specified group indexes.
Cc: linux-hardening@vger.kernel.org
Cc: stable@vger.kernel.org
Reported-by: Lukas Loidolt <e1634039@student.tuwien.ac.at>
Closes: https://lore.kernel.org/all/f3ca77f0-e414-4065-83a5-ae4c4d25545d@student.tuwien.ac.at
Fixes: 313dd1b62921 ("gcc-plugins: Add the randstruct plugin")
Signed-off-by: Kees Cook <keescook@chromium.org>
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In GCC 14, last_stmt() was renamed to last_nondebug_stmt(). Add a helper
macro to handle the renaming.
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
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The latest GCC 13 snapshot (13.0.1 20230129) gives the following:
```
cc1: error: cannot load plugin ./scripts/gcc-plugins/randomize_layout_plugin.so
:./scripts/gcc-plugins/randomize_layout_plugin.so: undefined symbol: tree_code_type
```
This ends up being because of https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=b0241ce6e37031
upstream in GCC which changes the visibility of some types used by the kernel's
plugin infrastructure like tree_code_type.
After discussion with the GCC folks, we found that the kernel needs to be building
plugins with the same flags used to build GCC - and GCC defaults to gnu++17
right now. The minimum GCC version needed to build the kernel is GCC 5.1
and GCC 5.1 already defaults to gnu++14 anyway, so just drop the flag, as
all GCCs that could be used to build GCC already default to an acceptable
version which was >= the version we forced via flags until now.
Bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108634
Signed-off-by: Sam James <sam@gentoo.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230201230009.2252783-1-sam@gentoo.org
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The gimple-iterator.h header must be included before gimple-fold.h
starting with GCC 13. Reorganize gimple headers to work for all GCC
versions.
Reported-by: Palmer Dabbelt <palmer@rivosinc.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Link: https://lore.kernel.org/all/20230113173033.4380-1-palmer@rivosinc.com/
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
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Based on the normalized pattern:
licensed under the gpl v2
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference.
Reviewed-by: Allison Randal <allison@lohutok.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Commit 61f60bac8c05 ("gcc-plugins: Change all version strings match
kernel") broke parallel builds.
Instead of adding the dependency between GCC plugins and utsrelease.h,
let's use KERNELVERSION, which does not require any build artifact.
Another reason why I want to avoid utsrelease.h is because it depends
on CONFIG_LOCALVERSION(_AUTO) and localversion* files.
(include/generated/utsrelease.h depends on include/config/kernel.release,
which is generated by scripts/setlocalversion)
I want to keep host tools independent of the kernel configuration.
There is no good reason to rebuild GCC plugins just because of
CONFIG_LOCALVERSION being changed.
We just want to associate the plugin versions with the kernel source
version. KERNELVERSION should be enough for our purpose.
Fixes: 61f60bac8c05 ("gcc-plugins: Change all version strings match kernel")
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/linux-mm/202205230239.EZxeZ3Fv-lkp@intel.com
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220524135541.1453693-1-masahiroy@kernel.org
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With all randstruct exceptions removed, remove all the exception
handling code. Any future warnings are likely to be shared between
this plugin and Clang randstruct, and will need to be addressed in a
more wholistic fashion.
Cc: Christoph Hellwig <hch@infradead.org>
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
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While preparing for Clang randstruct support (which duplicated many of
the warnings the randstruct GCC plugin warned about), one strange one
remained only for the randstruct GCC plugin. Eliminating this rids
the plugin of the last exception.
It seems the plugin is happy to dereference individual members of
a cross-struct cast, but it is upset about casting to a whole object
pointer. This only manifests in one place in the kernel, so just replace
the variable with individual member accesses. There is no change in
executable instruction output.
Drop the last exception from the randstruct GCC plugin.
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Cong Wang <cong.wang@bytedance.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: netdev@vger.kernel.org
Cc: linux-hardening@vger.kernel.org
Acked-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Link: https://lore.kernel.org/lkml/20220511022217.58586-1-kuniyu@amazon.co.jp
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/lkml/20220511151542.4cb3ff17@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
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Clang randstruct gets upset when it sees struct addresspace (which is
randomized) being assigned to a struct page (which is not randomized):
drivers/net/ethernet/sun/niu.c:3385:12: error: casting from randomized structure pointer type 'struct address_space *' to 'struct page *'
*link = (struct page *) page->mapping;
^
It looks like niu.c is looking for an in-line place to chain its allocated
pages together and is overloading the "mapping" member, as it is unused.
This is very non-standard, and is expected to be cleaned up in the
future[1], but there is no "correct" way to handle it today.
No meaningful machine code changes result after this change, and source
readability is improved.
Drop the randstruct exception now that there is no "confusing" cross-type
assignment.
[1] https://lore.kernel.org/lkml/YnqgjVoMDu5v9PNG@casper.infradead.org/
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Du Cheng <ducheng2@gmail.com>
Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: netdev@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-hardening@vger.kernel.org
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/lkml/20220511151647.7290adbe@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
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The randstruct GCC plugin gets upset when it sees struct path (which is
randomized) being assigned from a "void *" (which it cannot type-check).
There's no need for these casts, as the entire internal payload use is
following a normal struct layout. Convert the enum-based void * offset
dereferencing to the new big_key_payload struct. No meaningful machine
code changes result after this change, and source readability is improved.
Drop the randstruct exception now that there is no "confusing" cross-type
assignment.
Cc: David Howells <dhowells@redhat.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: linux-hardening@vger.kernel.org
Cc: keyrings@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
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It's not meaningful for the GCC plugins to track their versions separately
from the rest of the kernel. Switch all versions to the kernel version.
Fix mismatched indenting while we're at it.
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
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To enable Clang randstruct support, move the structure layout
randomization seed generation out of scripts/gcc-plugins/ into
scripts/basic/ so it happens early enough that it can be used by either
compiler implementation. The gcc-plugin still builds its own header file,
but now does so from the common "randstruct.seed" file.
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220503205503.3054173-6-keescook@chromium.org
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In preparation for Clang supporting randstruct, reorganize the Kconfigs,
move the attribute macros, and generalize the feature to be named
CONFIG_RANDSTRUCT for on/off, CONFIG_RANDSTRUCT_FULL for the full
randomization mode, and CONFIG_RANDSTRUCT_PERFORMANCE for the cache-line
sized mode.
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220503205503.3054173-4-keescook@chromium.org
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The initialization of "security_hook_heads" is done by casting it to
another structure pointer type, and treating it as an array of "struct
hlist_head" objects. This requires an exception be made in "randstruct",
because otherwise it will emit an error, reducing the effectiveness of
the hardening technique.
Instead of using a cast, initialize the individual struct hlist_head
elements in security_hook_heads explicitly. This removes the need for
the cast and randstruct exception.
Signed-off-by: Bill Wendling <morbo@google.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220407175930.471870-1-morbo@google.com
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While the latent entropy plugin mostly doesn't derive entropy from
get_random_const() for measuring the call graph, when __latent_entropy is
applied to a constant, then it's initialized statically to output from
get_random_const(). In that case, this data is derived from a 64-bit
seed, which means a buffer of 512 bits doesn't really have that amount
of compile-time entropy.
This patch fixes that shortcoming by just buffering chunks of
/dev/urandom output and doling it out as requested.
At the same time, it's important that we don't break the use of
-frandom-seed, for people who want the runtime benefits of the latent
entropy plugin, while still having compile-time determinism. In that
case, we detect whether gcc's set_random_seed() has been called by
making a call to get_random_seed(noinit=true) in the plugin init
function, which is called after set_random_seed() is called but before
anything that calls get_random_seed(noinit=false), and seeing if it's
zero or not. If it's not zero, we're in deterministic mode, and so we
just generate numbers with a basic xorshift prng.
Note that we don't detect if -frandom-seed is being used using the
documented local_tick variable, because it's assigned via:
local_tick = (unsigned) tv.tv_sec * 1000 + tv.tv_usec / 1000;
which may well overflow and become -1 on its own, and so isn't
reliable: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105171
[kees: The 256 byte rnd_buf size was chosen based on average (250),
median (64), and std deviation (575) bytes of used entropy for a
defconfig x86_64 build]
Fixes: 38addce8b600 ("gcc-plugins: Add latent_entropy plugin")
Cc: stable@vger.kernel.org
Cc: PaX Team <pageexec@freemail.hu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220405222815.21155-1-Jason@zx2c4.com
|
|
The .noinstr.text section functions may not have "current()" sanely
available. Similarly true for .entry.text, though such a check is
currently redundant. Add a check for both. In an x86_64 defconfig build,
the following functions no longer receive stackleak instrumentation:
__do_fast_syscall_32()
do_int80_syscall_32()
do_machine_check()
do_syscall_64()
exc_general_protection()
fixup_bad_iret()
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Cc: Alexander Popov <alex.popov@linux.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
Since STRING_CST may not be NUL terminated, strncmp() was used for check
for equality. However, this may lead to mismatches for longer section
names where the start matches the tested-for string. Test for exact
equality by checking for the presences of NUL termination.
Cc: Alexander Popov <alex.popov@linux.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
Pull ARM updates from Russell King:
- Rejig task/thread info to place thread info in task struct
- Amba bus cleanups (removing unused functions)
- Handle Amba device probe without IRQ domains
- Parse linux,usable-memory-range in decompressor
- Mark OCRAM as read-only after initialisation
- Refactor page fault handling
- Fix PXN handling with LPAE kernels
- Warning and build fixes from Arnd
* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: (32 commits)
ARM: 9151/1: Thumb2: avoid __builtin_thread_pointer() on Clang
ARM: 9150/1: Fix PID_IN_CONTEXTIDR regression when THREAD_INFO_IN_TASK=y
ARM: 9147/1: add printf format attribute to early_print()
ARM: 9146/1: RiscPC needs older gcc version
ARM: 9145/1: patch: fix BE32 compilation
ARM: 9144/1: forbid ftrace with clang and thumb2_kernel
ARM: 9143/1: add CONFIG_PHYS_OFFSET default values
ARM: 9142/1: kasan: work around LPAE build warning
ARM: 9140/1: allow compile-testing without machine record
ARM: 9137/1: disallow CONFIG_THUMB with ARMv4
ARM: 9136/1: ARMv7-M uses BE-8, not BE-32
ARM: 9135/1: kprobes: address gcc -Wempty-body warning
ARM: 9101/1: sa1100/assabet: convert LEDs to gpiod APIs
ARM: 9131/1: mm: Fix PXN process with LPAE feature
ARM: 9130/1: mm: Provide die_kernel_fault() helper
ARM: 9126/1: mm: Kill page table base print in show_pte()
ARM: 9127/1: mm: Cleanup access_error()
ARM: 9129/1: mm: Kill task_struct argument for __do_page_fault()
ARM: 9128/1: mm: Refactor the __do_page_fault()
ARM: imx6: mark OCRAM mapping read-only
...
|
|
'tree-ssa-operands.h' included in 'gcc-common.h' is duplicated.
it's also included at line 56.
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Ye Guojin <ye.guojin@zte.com.cn>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20211019082910.998257-1-ye.guojin@zte.com.cn
|
|
This plugin has no impact on the resulting binary, is disabled
under COMPILE_TEST, and is not enabled on any builds I'm aware of.
Additionally, given the clarified purpose of GCC plugins in the kernel,
remove cyc_complexity.
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-hardening@vger.kernel.org
Cc: linux-kbuild@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20211020173554.38122-3-keescook@chromium.org
|
|
GCC plugins should only exist when some compiler feature needs to be
proven but does not exist in either GCC nor Clang. For example, if a
desired feature is already in Clang, it should be added to GCC upstream.
Document this explicitly.
Additionally, mark the plugins with matching upstream GCC features as
removable past their respective GCC versions.
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: linux-hardening@vger.kernel.org
Cc: linux-kbuild@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: llvm@lists.linux.dev
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20211020173554.38122-2-keescook@chromium.org
|
|
The minimum GCC version has been bumped to 5.1, so we can get rid of all
the compatibility code for anything older than that.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210922182632.633394-1-ardb@kernel.org
|
|
We will be enabling THREAD_INFO_IN_TASK support for ARM, which means
that we can no longer load the stack canary value by masking the stack
pointer and taking the copy that lives in thread_info. Instead, we will
be able to load it from the task_struct directly, by using the TPIDRURO
register which will hold the current task pointer when
THREAD_INFO_IN_TASK is in effect. This is much more straight-forward,
and allows us to declutter this code a bit while at it.
Note that this means that ARMv6 (non-v6K) SMP systems can no longer use
this feature, but those are quite rare to begin with, so this is a
reasonable trade off.
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
|
|
Set the x bit to some scripts to make them directly executable.
Especially, scripts/checkdeclares.pl is not hooked by anyone.
It should be executable since it is tedious to type
'perl scripts/checkdeclares.pl'.
The original patch [1] set the x bit properly, but it was lost when
it was merged as commit 21917bded72c ("scripts: a new script for
checking duplicate struct declaration").
[1] https://lore.kernel.org/lkml/20210401110943.1010796-1-wanjiabing@vivo.com/
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
|
The pattern prefixed with '/' matches files in the same directory,
but not ones in sub-directories.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Andra Paraschiv <andraprs@amazon.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Gabriel Krisman Bertazi <krisman@collabora.com>
|
|
Linus reported a build error due to the GCC plugin incompatibility
when the compiler is upgraded. [1]
GCC plugins are tied to a particular GCC version. So, they must be
rebuilt when the compiler is upgraded.
This seems to be a long-standing flaw since the initial support of
GCC plugins.
Extend commit 8b59cd81dc5e ("kbuild: ensure full rebuild when the
compiler is updated"), so that GCC plugins are covered by the
compiler upgrade detection.
[1]: https://lore.kernel.org/lkml/CAHk-=wieoN5ttOy7SnsGwZv+Fni3R6m-Ut=oxih6bbZ28G+4dw@mail.gmail.com/
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
|
|
Fix the following coccicheck warning:
scripts/gcc-plugins/latent_entropy_plugin.c:539:2-3: Unneeded semicolon
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20200418070521.10931-1-yanaijie@huawei.com
|
|
Fix the following coccicheck warning:
scripts/gcc-plugins/structleak_plugin.c:177:14-17: Unneeded variable:
"ret". Return "0" on line 207
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20200418070505.10715-1-yanaijie@huawei.com
|
|
Fedora Rawhide has started including gcc 11,and the g++ compiler
throws a wobbly when it hits scripts/gcc-plugins:
HOSTCXX scripts/gcc-plugins/latent_entropy_plugin.so
In file included from /usr/include/c++/11/type_traits:35,
from /usr/lib/gcc/x86_64-redhat-linux/11/plugin/include/system.h:244,
from /usr/lib/gcc/x86_64-redhat-linux/11/plugin/include/gcc-plugin.h:28,
from scripts/gcc-plugins/gcc-common.h:7,
from scripts/gcc-plugins/latent_entropy_plugin.c:78:
/usr/include/c++/11/bits/c++0x_warning.h:32:2: error: #error This file requires compiler and library support for the ISO
C++ 2011 standard. This support must be enabled with the -std=c++11 or -std=gnu++11 compiler options.
32 | #error This file requires compiler and library support \
In fact, it works just fine with c++11, which has been in gcc since 4.8,
and we now require 4.9 as a minimum.
Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/82487.1609006918@turing-police
|
|
Linus pointed out a third of the time in the Kconfig parse stage comes
from the single invocation of cc1plus in scripts/gcc-plugin.sh [1],
and directly testing plugin-version.h for existence cuts down the
overhead a lot. [2]
This commit takes one step further to kill the build test entirely.
The small piece of code was probably intended to test the C++ designated
initializer, which was not supported until C++20.
In fact, with -pedantic option given, both GCC and Clang emit a warning.
$ echo 'class test { public: int test; } test = { .test = 1 };' | g++ -x c++ -pedantic - -fsyntax-only
<stdin>:1:43: warning: C++ designated initializers only available with '-std=c++2a' or '-std=gnu++2a' [-Wpedantic]
$ echo 'class test { public: int test; } test = { .test = 1 };' | clang++ -x c++ -pedantic - -fsyntax-only
<stdin>:1:43: warning: designated initializers are a C++20 extension [-Wc++20-designator]
class test { public: int test; } test = { .test = 1 };
^
1 warning generated.
Otherwise, modern C++ compilers should be able to build the code, and
hopefully skipping this test should not make any practical problem.
Checking the existence of plugin-version.h is still needed to ensure
the plugin-dev package is installed. The test code is now small enough
to be embedded in scripts/gcc-plugins/Kconfig.
[1] https://lore.kernel.org/lkml/CAHk-=wjU4DCuwQ4pXshRbwDCUQB31ScaeuDo1tjoZ0_PjhLHzQ@mail.gmail.com/
[2] https://lore.kernel.org/lkml/CAHk-=whK0aQxs6Q5ijJmYF1n2ch8cVFSUzU5yUM_HOjig=+vnw@mail.gmail.com/
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201203125700.161354-1-masahiroy@kernel.org
|
|
Documentation/process/changes.rst says the minimal GCC version is 4.9.
Hence, BUILDING_GCC_VERSION is greater than or equal to 4009.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201202134929.99883-1-masahiroy@kernel.org
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- run the checker (e.g. sparse) after the compiler
- remove unneeded cc-option tests for old compiler flags
- fix tar-pkg to install dtbs
- introduce ccflags-remove-y and asflags-remove-y syntax
- allow to trace functions in sub-directories of lib/
- introduce hostprogs-always-y and userprogs-always-y syntax
- various Makefile cleanups
* tag 'kbuild-v5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kbuild: stop filtering out $(GCC_PLUGINS_CFLAGS) from cc-option base
kbuild: include scripts/Makefile.* only when relevant CONFIG is enabled
kbuild: introduce hostprogs-always-y and userprogs-always-y
kbuild: sort hostprogs before passing it to ifneq
kbuild: move host .so build rules to scripts/gcc-plugins/Makefile
kbuild: Replace HTTP links with HTTPS ones
kbuild: trace functions in subdirectories of lib/
kbuild: introduce ccflags-remove-y and asflags-remove-y
kbuild: do not export LDFLAGS_vmlinux
kbuild: always create directories of targets
powerpc/boot: add DTB to 'targets'
kbuild: buildtar: add dtbs support
kbuild: remove cc-option test of -ffreestanding
kbuild: remove cc-option test of -fno-stack-protector
Revert "kbuild: Create directory for target DTB"
kbuild: run the checker after the compiler
|
|
The host shared library rules are currently implemented in
scripts/Makefile.host, but actually GCC-plugin is the only user of
them. (The VDSO .so files are built for the target by different
build rules) Hence, they do not need to be treewide available.
Move all the relevant build rules to scripts/gcc-plugins/Makefile.
I also optimized the build steps so *.so is directly built from .c
because every upstream plugin is compiled from a single source file.
I am still keeping the multi-file plugin support, which Kees Cook
mentioned might be needed by out-of-tree plugins.
(https://lkml.org/lkml/2019/1/11/1107)
If the plugin, foo.so, is compiled from two files foo.c and foo2.c,
then you can do like follows:
foo-objs := foo.o foo2.o
Single-file plugins do not need the *-objs notation.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull gcc plugin updates from Kees Cook:
"Primarily improvements to STACKLEAK from Alexander Popov, along with
some additional cleanups.
- Update URLs for HTTPS scheme where available (Alexander A. Klimov)
- Improve STACKLEAK code generation on x86 (Alexander Popov)"
* tag 'gcc-plugins-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
gcc-plugins: Replace HTTP links with HTTPS ones
gcc-plugins/stackleak: Add 'verbose' plugin parameter
gcc-plugins/stackleak: Use asm instrumentation to avoid useless register saving
ARM: vdso: Don't use gcc plugins for building vgettimeofday.c
gcc-plugins/stackleak: Don't instrument itself
|
|
Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.
Deterministic algorithm:
For each file:
If not .svg:
For each line:
If doesn't contain `\bxmlns\b`:
For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`:
If both the HTTP and HTTPS versions
return 200 OK and serve the same content:
Replace HTTP with HTTPS.
Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
Link: https://lore.kernel.org/r/20200713135018.34708-1-grandmaster@al2klimov.de
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
Fix typos "plgins" -> "plugins".
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
|
|
Add 'verbose' plugin parameter for stackleak gcc plugin.
It can be used for printing additional info about the kernel code
instrumentation.
For using it add the following to scripts/Makefile.gcc-plugins:
gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \
+= -fplugin-arg-stackleak_plugin-verbose
Signed-off-by: Alexander Popov <alex.popov@linux.com>
Link: https://lore.kernel.org/r/20200624123330.83226-6-alex.popov@linux.com
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
The kernel code instrumentation in stackleak gcc plugin works in two stages.
At first, stack tracking is added to GIMPLE representation of every function
(except some special cases). And later, when stack frame size info is
available, stack tracking is removed from the RTL representation of the
functions with small stack frame. There is an unwanted side-effect for these
functions: some of them do useless work with caller-saved registers.
As an example of such case, proc_sys_write without() instrumentation:
55 push %rbp
41 b8 01 00 00 00 mov $0x1,%r8d
48 89 e5 mov %rsp,%rbp
e8 11 ff ff ff callq ffffffff81284610 <proc_sys_call_handler>
5d pop %rbp
c3 retq
0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1)
00 00 00
proc_sys_write() with instrumentation:
55 push %rbp
48 89 e5 mov %rsp,%rbp
41 56 push %r14
41 55 push %r13
41 54 push %r12
53 push %rbx
49 89 f4 mov %rsi,%r12
48 89 fb mov %rdi,%rbx
49 89 d5 mov %rdx,%r13
49 89 ce mov %rcx,%r14
4c 89 f1 mov %r14,%rcx
4c 89 ea mov %r13,%rdx
4c 89 e6 mov %r12,%rsi
48 89 df mov %rbx,%rdi
41 b8 01 00 00 00 mov $0x1,%r8d
e8 f2 fe ff ff callq ffffffff81298e80 <proc_sys_call_handler>
5b pop %rbx
41 5c pop %r12
41 5d pop %r13
41 5e pop %r14
5d pop %rbp
c3 retq
66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1)
00 00
Let's improve the instrumentation to avoid this:
1. Make stackleak_track_stack() save all register that it works with.
Use no_caller_saved_registers attribute for that function. This attribute
is available for x86_64 and i386 starting from gcc-7.
2. Insert calling stackleak_track_stack() in asm:
asm volatile("call stackleak_track_stack" :: "r" (current_stack_pointer))
Here we use ASM_CALL_CONSTRAINT trick from arch/x86/include/asm/asm.h.
The input constraint is taken into account during gcc shrink-wrapping
optimization. It is needed to be sure that stackleak_track_stack() call is
inserted after the prologue of the containing function, when the stack
frame is prepared.
This work is a deep reengineering of the idea described on grsecurity blog
https://grsecurity.net/resolving_an_unfortunate_stackleak_interaction
Signed-off-by: Alexander Popov <alex.popov@linux.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Link: https://lore.kernel.org/r/20200624123330.83226-5-alex.popov@linux.com
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/will/linux
Pull READ/WRITE_ONCE rework from Will Deacon:
"This the READ_ONCE rework I've been working on for a while, which
bumps the minimum GCC version and improves code-gen on arm64 when
stack protector is enabled"
[ Side note: I'm _really_ tempted to raise the minimum gcc version to
4.9, so that we can just say that we require _Generic() support.
That would allow us to more cleanly handle a lot of the cases where we
depend on very complex macros with 'sizeof' or __builtin_choose_expr()
with __builtin_types_compatible_p() etc.
This branch has a workaround for sparse not handling _Generic(),
either, but that was already fixed in the sparse development branch,
so it's really just gcc-4.9 that we'd require. - Linus ]
* 'rwonce/rework' of git://git.kernel.org/pub/scm/linux/kernel/git/will/linux:
compiler_types.h: Use unoptimized __unqual_scalar_typeof for sparse
compiler_types.h: Optimize __unqual_scalar_typeof compilation time
compiler.h: Enforce that READ_ONCE_NOCHECK() access size is sizeof(long)
compiler-types.h: Include naked type in __pick_integer_type() match
READ_ONCE: Fix comment describing 2x32-bit atomicity
gcov: Remove old GCC 3.4 support
arm64: barrier: Use '__unqual_scalar_typeof' for acquire/release macros
locking/barriers: Use '__unqual_scalar_typeof' for load-acquire macros
READ_ONCE: Drop pointer qualifiers when reading from scalar types
READ_ONCE: Enforce atomicity for {READ,WRITE}_ONCE() memory accesses
READ_ONCE: Simplify implementations of {READ,WRITE}_ONCE()
arm64: csum: Disable KASAN for do_csum()
fault_inject: Don't rely on "return value" from WRITE_ONCE()
net: tls: Avoid assigning 'const' pointer to non-const pointer
netfilter: Avoid assigning 'const' pointer to non-const pointer
compiler/gcc: Raise minimum GCC version for kernel builds to 4.8
|
|
This is the remnant of commit c17d6179ad5a ("gcc-plugins: remove unused
GCC_PLUGIN_SUBDIR").
The conditional $(if $(findstring /,$(p)),...) is always false because
none of plugins contains '/' in the file name.
Clean up the code.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
|
|
It is very rare to see versions of GCC prior to 4.8 being used to build
the mainline kernel. These old compilers are also know to have codegen
issues which can lead to silent miscompilation:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145
Raise the minimum GCC version for kernel build to 4.8 and remove some
tautological Kconfig dependencies as a consequence.
Cc: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
|
|
Remove "params.h" include, which has been dropped in GCC 10.
Remove is_a_helper() macro, which is now defined in gimple.h, as seen
when running './scripts/gcc-plugin.sh g++ g++ gcc':
In file included from <stdin>:1:
./gcc-plugins/gcc-common.h:852:13: error: redefinition of ‘static bool is_a_helper<T>::test(U*) [with U = const gimple; T = const ggoto*]’
852 | inline bool is_a_helper<const ggoto *>::test(const_gimple gs)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ./gcc-plugins/gcc-common.h:125,
from <stdin>:1:
/usr/lib/gcc/x86_64-redhat-linux/10/plugin/include/gimple.h:1037:1: note: ‘static bool is_a_helper<T>::test(U*) [with U = const gimple; T = const ggoto*]’ previously declared here
1037 | is_a_helper <const ggoto *>::test (const gimple *gs)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
Add -Wno-format-diag to scripts/gcc-plugins/Makefile to avoid
meaningless warnings from error() formats used by plugins:
scripts/gcc-plugins/structleak_plugin.c: In function ‘int plugin_init(plugin_name_args*, plugin_gcc_version*)’:
scripts/gcc-plugins/structleak_plugin.c:253:12: warning: unquoted sequence of 2 consecutive punctuation characters ‘'-’ in format [-Wformat-diag]
253 | error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Signed-off-by: Frédéric Pierret (fepitre) <frederic.pierret@qubes-os.org>
Link: https://lore.kernel.org/r/20200407113259.270172-1-frederic.pierret@qubes-os.org
[kees: include -Wno-format-diag for plugin builds]
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
With GCC version >= 8, the cgraph_create_edge() macro argument using
"frequency" goes unused. Instead of assigning a temporary variable for
the argument, pass the compute_call_stmt_bb_frequency() call directly
as the macro argument so that it will just not be called when it is
not wanted by the macros.
Silences the warning:
scripts/gcc-plugins/stackleak_plugin.c:54:6: warning: variable ‘frequency’ set but not used [-Wunused-but-set-variable]
Now builds cleanly with gcc-7 and gcc-9. Both boot and pass
STACKLEAK_ERASING LKDTM test.
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
Nobody was opposed to raising minimum GCC version to 4.8 [1]
So, we will drop GCC <= 4.7 support sooner or later.
We always use C++ compiler for building plugins for GCC >= 4.8.
This commit drops the plugin support for GCC <= 4.7 a bit earlier,
which allows us to dump lots of code.
[1] https://lkml.org/lkml/2020/1/23/545
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx
Pull SPDX updates from Greg KH:
"Here are three SPDX patches for 5.7-rc1.
One fixes up the SPDX tag for a single driver, while the other two go
through the tree and add SPDX tags for all of the .gitignore files as
needed.
Nothing too complex, but you will get a merge conflict with your
current tree, that should be trivial to handle (one file modified by
two things, one file deleted.)
All three of these have been in linux-next for a while, with no
reported issues other than the merge conflict"
* tag 'spdx-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx:
ASoC: MT6660: make spdxcheck.py happy
.gitignore: add SPDX License Identifier
.gitignore: remove too obvious comments
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
"Build system:
- add CONFIG_UNUSED_KSYMS_WHITELIST, which will be useful to define a
fixed set of export symbols for Generic Kernel Image (GKI)
- allow to run 'make dt_binding_check' without .config
- use full schema for checking DT examples in *.yaml files
- make modpost fail for missing MODULE_IMPORT_NS(), which makes more
sense because we know the produced modules are never loadable
- Remove unused 'AS' variable
Kconfig:
- sanitize DEFCONFIG_LIST, and remove ARCH_DEFCONFIG from Kconfig
files
- relax the 'imply' behavior so that symbols implied by 'y' can
become 'm'
- make 'imply' obey 'depends on' in order to make 'imply' really weak
Misc:
- add documentation on building the kernel with Clang/LLVM
- revive __HAVE_ARCH_STRLEN for 32bit sparc to use optimized strlen()
- fix warning from deb-pkg builds when CONFIG_DEBUG_INFO=n
- various script and Makefile cleanups"
* tag 'kbuild-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (34 commits)
Makefile: Update kselftest help information
kbuild: deb-pkg: fix warning when CONFIG_DEBUG_INFO is unset
kbuild: add outputmakefile to no-dot-config-targets
kbuild: remove AS variable
net: wan: wanxl: refactor the firmware rebuild rule
net: wan: wanxl: use $(M68KCC) instead of $(M68KAS) for rebuilding firmware
net: wan: wanxl: use allow to pass CROSS_COMPILE_M68k for rebuilding firmware
kbuild: add comment about grouped target
kbuild: add -Wall to KBUILD_HOSTCXXFLAGS
kconfig: remove unused variable in qconf.cc
sparc: revive __HAVE_ARCH_STRLEN for 32bit sparc
kbuild: refactor Makefile.dtbinst more
kbuild: compute the dtbs_install destination more simply
Makefile: disallow data races on gcc-10 as well
kconfig: make 'imply' obey the direct dependency
kconfig: allow symbols implied by y to become m
net: drop_monitor: use IS_REACHABLE() to guard net_dm_hw_report()
modpost: return error if module is missing ns imports and MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n
modpost: rework and consolidate logging interface
kbuild: allow to run dt_binding_check without kernel configuration
...
|
|
Add -Wall to catch more warnings for C++ host programs.
When I submitted the previous version, the 0-day bot reported
-Wc++11-compat warnings for old GCC:
HOSTCXX -fPIC scripts/gcc-plugins/latent_entropy_plugin.o
In file included from /usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/tm.h:28:0,
from scripts/gcc-plugins/gcc-common.h:15,
from scripts/gcc-plugins/latent_entropy_plugin.c:78:
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/elfos.h:102:21: warning: C++11 requires a space between string literal and macro [-Wc++11-compat]
fprintf ((FILE), "%s"HOST_WIDE_INT_PRINT_UNSIGNED"\n",\
^
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/elfos.h:170:24: warning: C++11 requires a space between string literal and macro [-Wc++11-compat]
fprintf ((FILE), ","HOST_WIDE_INT_PRINT_UNSIGNED",%u\n", \
^
In file included from /usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/tm.h:42:0,
from scripts/gcc-plugins/gcc-common.h:15,
from scripts/gcc-plugins/latent_entropy_plugin.c:78:
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/defaults.h:126:24: warning: C++11 requires a space between string literal and macro [-Wc++11-compat]
fprintf ((FILE), ","HOST_WIDE_INT_PRINT_UNSIGNED",%u\n", \
^
The source of the warnings is in the plugin headers, so we have no
control of it. I just suppressed them by adding -Wno-c++11-compat to
scripts/gcc-plugins/Makefile.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
|
|
Add SPDX License Identifier to all .gitignore files.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Information about GCC plugins is relevant to kernel building, so move this
document to the kbuild manual.
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
|
|
In old days, the "host-progs" syntax was used for specifying host
programs. It was renamed to the current "hostprogs-y" in 2004.
It is typically useful in scripts/Makefile because it allows Kbuild to
selectively compile host programs based on the kernel configuration.
This commit renames like follows:
always -> always-y
hostprogs-y -> hostprogs
So, scripts/Makefile will look like this:
always-$(CONFIG_BUILD_BIN2C) += ...
always-$(CONFIG_KALLSYMS) += ...
...
hostprogs := $(always-y) $(always-m)
I think this makes more sense because a host program is always a host
program, irrespective of the kernel configuration. We want to specify
which ones to compile by CONFIG options, so always-y will be handier.
The "always", "hostprogs-y", "hostprogs-m" will be kept for backward
compatibility for a while.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
|
I noticed that randconfig builds with gcc no longer produce a lot of
ccache hits, unlike with clang, and traced this back to plugins
now being enabled unconditionally if they are supported.
I am now working around this by adding
export CCACHE_COMPILERCHECK=/usr/bin/size -A %compiler%
to my top-level Makefile. This changes the heuristic that ccache uses
to determine whether the plugins are the same after a 'make clean'.
However, it also seems that being able to just turn off the plugins is
generally useful, at least for build testing it adds noticeable overhead
but does not find a lot of bugs additional bugs, and may be easier for
ccache users than my workaround.
Fixes: 9f671e58159a ("security: Create "kernel hardening" config area")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20191211133951.401933-1-arnd@arndb.de
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
While no uses in the kernel triggered this case, it was possible to have
a false negative where a struct contains other structs which contain only
function pointers because of unreachable code in is_pure_ops_struct().
Signed-off-by: Joonwon Kang <kjw1627@gmail.com>
Link: https://lore.kernel.org/r/20190727155841.GA13586@host
Fixes: 313dd1b62921 ("gcc-plugins: Add the randstruct plugin")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
The gcc_plugins.txt file is already a ReST file. Move it
to the core-api book while renaming it.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull gcc-plugins fix from Kees Cook:
"Handle unusual header environment, fixing a redefined macro error
under a Darwin build host"
* tag 'gcc-plugins-v5.2-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
gcc-plugins: Fix build failures under Darwin host
|
|
Add SPDX license identifiers to all Make/Kconfig files which:
- Have no license information of any form
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
The gcc-common.h file did not take into account certain macros that
might have already been defined in the build environment. This updates
the header to avoid redefining the macros, as seen on a Darwin host
using gcc 4.9.2:
HOSTCXX -fPIC scripts/gcc-plugins/arm_ssp_per_task_plugin.o - due to: scripts/gcc-plugins/gcc-common.h
In file included from scripts/gcc-plugins/arm_ssp_per_task_plugin.c:3:0:
scripts/gcc-plugins/gcc-common.h:153:0: warning: "__unused" redefined
^
In file included from /usr/include/stdio.h:64:0,
from /Users/hns/Documents/Projects/QuantumSTEP/System/Library/Frameworks/System.framework/Versions-jessie/x86_64-apple-darwin15.0.0/gcc/arm-linux-gnueabi/bin/../lib/gcc/arm-linux-gnueabi/4.9.2/plugin/include/system.h:40,
from /Users/hns/Documents/Projects/QuantumSTEP/System/Library/Frameworks/System.framework/Versions-jessie/x86_64-apple-darwin15.0.0/gcc/arm-linux-gnueabi/bin/../lib/gcc/arm-linux-gnueabi/4.9.2/plugin/include/gcc-plugin.h:28,
from /Users/hns/Documents/Projects/QuantumSTEP/System/Library/Frameworks/System.framework/Versions-jessie/x86_64-apple-darwin15.0.0/gcc/arm-linux-gnueabi/bin/../lib/gcc/arm-linux-gnueabi/4.9.2/plugin/include/plugin.h:23,
from scripts/gcc-plugins/gcc-common.h:9,
from scripts/gcc-plugins/arm_ssp_per_task_plugin.c:3:
/usr/include/sys/cdefs.h:161:0: note: this is the location of the previous definition
^
Reported-and-tested-by: "H. Nikolaus Schaller" <hns@goldelico.com>
Fixes: 189af4657186 ("ARM: smp: add support for per-task stack canaries")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull gcc plugin fix from Kees Cook:
"Fix ARM stack-protector-per-task plugin build for older GCC < 6 (Chris
Packham)"
* tag 'gcc-plugins-v5.2-rc1' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/kees/linux:
gcc-plugins: arm_ssp_per_task_plugin: Fix for older GCC < 6
|
|
Use gen_rtx_set instead of gen_rtx_SET. The former is a wrapper macro
that handles the difference between GCC versions implementing
the latter.
This fixes the following error on my system with g++ 5.4.0 as the host
compiler
HOSTCXX -fPIC scripts/gcc-plugins/arm_ssp_per_task_plugin.o
scripts/gcc-plugins/arm_ssp_per_task_plugin.c:42:14: error: macro "gen_rtx_SET" requires 3 arguments, but only 2 given
mask)),
^
scripts/gcc-plugins/arm_ssp_per_task_plugin.c: In function ‘unsigned int arm_pertask_ssp_rtl_execute()’:
scripts/gcc-plugins/arm_ssp_per_task_plugin.c:39:20: error: ‘gen_rtx_SET’ was not declared in this scope
emit_insn_before(gen_rtx_SET
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Fixes: 189af4657186 ("ARM: smp: add support for per-task stack canaries")
Cc: stable@vger.kernel.org
Tested-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
This moves the stackleak plugin options to Kconfig.hardening's memory
initialization menu.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Alexander Popov <alex.popov@linux.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
|
|
Right now kernel hardening options are scattered around various Kconfig
files. This can be a central place to collect these kinds of options
going forward. This is initially populated with the memory initialization
options from the gcc-plugins.
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull gcc-plugins updates from Kees Cook:
"This adds additional type coverage to the existing structleak plugin
and adds a large set of selftests to help evaluate stack variable
zero-initialization coverage.
That can be used to test whatever instrumentation might be performing
zero-initialization: either with the structleak plugin or with Clang's
coming "-ftrivial-auto-var-init=zero" option.
Summary:
- Add scalar and array initialization coverage
- Refactor Kconfig to make options more clear
- Add self-test module for testing automatic initialization"
* tag 'gcc-plugins-v5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
lib: Introduce test_stackinit module
gcc-plugins: structleak: Generalize to all variable types
|
|
Use after scope bugs detector seems to be almost entirely useless for
the linux kernel. It exists over two years, but I've seen only one
valid bug so far [1]. And the bug was fixed before it has been
reported. There were some other use-after-scope reports, but they were
false-positives due to different reasons like incompatibility with
structleak plugin.
This feature significantly increases stack usage, especially with GCC <
9 version, and causes a 32K stack overflow. It probably adds
performance penalty too.
Given all that, let's remove use-after-scope detector entirely.
While preparing this patch I've noticed that we mistakenly enable
use-after-scope detection for clang compiler regardless of
CONFIG_KASAN_EXTRA setting. This is also fixed now.
[1] http://lkml.kernel.org/r/<20171129052106.rhgbjhhis53hkgfn@wfg-t540p.sh.intel.com>
Link: http://lkml.kernel.org/r/20190111185842.13978-1-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Will Deacon <will.deacon@arm.com> [arm64]
Cc: Qian Cai <cai@lca.pw>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
This adjusts structleak to also work with non-struct types when they
are passed by reference, since those variables may leak just like
anything else. This is exposed via an improved set of Kconfig options.
(This does mean structleak is slightly misnamed now.)
Building with CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL should give the
kernel complete initialization coverage of all stack variables passed
by reference, including padding (see lib/test_stackinit.c).
Using CONFIG_GCC_PLUGIN_STRUCTLEAK_VERBOSE to count added initializations
under defconfig:
..._BYREF: 5945 added initializations
..._BYREF_ALL: 16606 added initializations
There is virtually no change to text+data size (both have less than 0.05%
growth):
text data bss dec hex filename
19502103 5051456 1917000 26470559 193e89f vmlinux.stock
19513412 5051456 1908808 26473676 193f4cc vmlinux.byref
19516974 5047360 1900616 26464950 193d2b6 vmlinux.byref_all
The measured performance difference is in the noise for hackbench and
kernel build benchmarks:
Stock:
5x hackbench -g 20 -l 1000
Mean: 10.649s
Std Dev: 0.339
5x kernel build (4-way parallel)
Mean: 261.98s
Std Dev: 1.53
CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF:
5x hackbench -g 20 -l 1000
Mean: 10.540s
Std Dev: 0.233
5x kernel build (4-way parallel)
Mean: 260.52s
Std Dev: 1.31
CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL:
5x hackbench -g 20 -l 1000
Mean: 10.320
Std Dev: 0.413
5x kernel build (4-way parallel)
Mean: 260.10
Std Dev: 0.86
This does not yet solve missing padding initialization for structures
on the stack that are never passed by reference (which should be a tiny
minority). Hopefully this will be more easily addressed by upstream
compiler fixes after clarifying the C11 padding initialization
specification.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
|
|
GCC 9 reworks the way the references to the stack canary are
emitted, to prevent the value from being spilled to the stack
before the final comparison in the epilogue, defeating the
purpose, given that the spill slot is under control of the
attacker that we are protecting ourselves from.
Since our canary value address is obtained without accessing
memory (as opposed to pre-v7 code that will obtain it from a
literal pool), it is unlikely (although not guaranteed) that
the compiler will spill the canary value in the same way, so
let's just disable this improvement when building with GCC9+.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
The ARM per-task stack protector GCC plugin hits an assert in
the compiler in some case, due to the fact the the SP mask
expression is not sign-extended as it should be. So fix that.
Suggested-by: Kugan Vivekanandarajah <kugan.vivekanandarajah@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull gcc-plugins update from Kees Cook:
"Both arm and arm64 are gaining per-task stack canaries (to match x86),
but arm is being done with a gcc plugin, hence it going through the
gcc-plugins tree.
New gcc-plugin:
- Enable per-task stack protector for ARM (Ard Biesheuvel)"
* tag 'gcc-plugins-v4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
ARM: smp: add support for per-task stack canaries
|
|
On ARM, we currently only change the value of the stack canary when
switching tasks if the kernel was built for UP. On SMP kernels, this
is impossible since the stack canary value is obtained via a global
symbol reference, which means
a) all running tasks on all CPUs must use the same value
b) we can only modify the value when no kernel stack frames are live
on any CPU, which is effectively never.
So instead, use a GCC plugin to add a RTL pass that replaces each
reference to the address of the __stack_chk_guard symbol with an
expression that produces the address of the 'stack_canary' field
that is added to struct thread_info. This way, each task will use
its own randomized value.
Cc: Russell King <linux@armlinux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Emese Revfy <re.emese@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Laura Abbott <labbott@redhat.com>
Cc: kernel-hardening@lists.openwall.com
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
Currently the 'stackleak_cleanup' pass deleting a CALL insn is executed
after the 'reload' pass. That allows gcc to do some weird optimization in
function prologues and epilogues, which are generated later [1].
Let's avoid that by registering the 'stackleak_cleanup' pass before
the '*free_cfg' pass. It's the moment when the stack frame size is
already final, function prologues and epilogues are generated, and the
machine-dependent code transformations are not done.
[1] https://www.openwall.com/lists/kernel-hardening/2018/11/23/2
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Alexander Popov <alex.popov@linux.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
Introduce CONFIG_STACKLEAK_RUNTIME_DISABLE option, which provides
'stack_erasing' sysctl. It can be used in runtime to control kernel
stack erasing for kernels built with CONFIG_GCC_PLUGIN_STACKLEAK.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Alexander Popov <alex.popov@linux.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
Introduce CONFIG_STACKLEAK_METRICS providing STACKLEAK information about
tasks via the /proc file system. In particular, /proc/<pid>/stack_depth
shows the maximum kernel stack consumption for the current and previous
syscalls. Although this information is not precise, it can be useful for
estimating the STACKLEAK performance impact for your workloads.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Alexander Popov <alex.popov@linux.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
The STACKLEAK feature erases the kernel stack before returning from
syscalls. That reduces the information which kernel stack leak bugs can
reveal and blocks some uninitialized stack variable attacks.
This commit introduces the STACKLEAK gcc plugin. It is needed for
tracking the lowest border of the kernel stack, which is important
for the code erasing the used part of the kernel stack at the end
of syscalls (comes in a separate commit).
The STACKLEAK feature is ported from grsecurity/PaX. More information at:
https://grsecurity.net/
https://pax.grsecurity.net/
This code is modified from Brad Spengler/PaX Team's code in the last
public patch of grsecurity/PaX based on our understanding of the code.
Changes or omissions from the original code are ours and don't reflect
the original grsecurity/PaX code.
Signed-off-by: Alexander Popov <alex.popov@linux.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
|
|
The STACKLEAK feature (initially developed by PaX Team) has the following
benefits:
1. Reduces the information that can be revealed through kernel stack leak
bugs. The idea of erasing the thread stack at the end of syscalls is
similar to CONFIG_PAGE_POISONING and memzero_explicit() in kernel
crypto, which all comply with FDP_RIP.2 (Full Residual Information
Protection) of the Common Criteria standard.
2. Blocks some uninitialized stack variable attacks (e.g. CVE-2017-17712,
CVE-2010-2963). That kind of bugs should be killed by improving C
compilers in future, which might take a long time.
This commit introduces the code filling the used part of the kernel
stack with a poison value before returning to userspace. Full
STACKLEAK feature also contains the gcc plugin which comes in a
separate commit.
The STACKLEAK feature is ported from grsecurity/PaX. More information at:
https://grsecurity.net/
https://pax.grsecurity.net/
This code is modified from Brad Spengler/PaX Team's code in the last
public patch of grsecurity/PaX based on our understanding of the code.
Changes or omissions from the original code are ours and don't reflect
the original grsecurity/PaX code.
Performance impact:
Hardware: Intel Core i7-4770, 16 GB RAM
Test #1: building the Linux kernel on a single core
0.91% slowdown
Test #2: hackbench -s 4096 -l 2000 -g 15 -f 25 -P
4.2% slowdown
So the STACKLEAK description in Kconfig includes: "The tradeoff is the
performance impact: on a single CPU system kernel compilation sees a 1%
slowdown, other systems and workloads may vary and you are advised to
test this feature on your expected workload before deploying it".
Signed-off-by: Alexander Popov <alex.popov@linux.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull gcc plugin fix from Kees Cook:
"Lift gcc test into Kconfig. This is for better behavior when the
kernel is built with Clang, reported by Stefan Agner"
* tag 'gcc-plugins-v4.19-rc1-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
gcc-plugins: Disable when building under Clang
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Prior to doing compiler feature detection in Kconfig, attempts to build
GCC plugins with Clang would fail the build, much in the same way missing
GCC plugin headers would fail the build. However, now that this logic
has been lifted into Kconfig, add an explicit test for GCC (instead of
duplicating it in the feature-test script).
Reported-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Drop useless redefinitions of cgraph_create_edge* macros. Drop the unused
nest argument. Also support gcc-8, which doesn't have freq argument.
Signed-off-by: Alexander Popov <alex.popov@linux.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
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Collect relevant code into the scripts/gcc-plugins directory.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
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GCC_PLUGIN_SUBDIR has never been used. If you really need this in
the future, please re-add it then.
For now, the code is unused. Remove.
'export HOSTLIBS' is not necessary either.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
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Run scripts/gcc-plugin.sh from Kconfig so that users can enable
GCC_PLUGINS only when the compiler supports building plugins.
Kconfig defines a new symbol, PLUGIN_HOSTCC. This will contain
the compiler (g++ or gcc) used for building plugins, or empty
if the plugin can not be supported at all.
This allows us to remove all ugly testing in Makefile.gcc-plugins.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Kees Cook <keescook@chromium.org>
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As Documentation/kbuild/kconfig-language.txt notes, 'select' should be
be used with care - it forces a lower limit of another symbol, ignoring
the dependency. Currently, KCOV can select GCC_PLUGINS even if arch
does not select HAVE_GCC_PLUGINS. This could cause the unmet direct
dependency.
Now that Kconfig can test compiler capability, let's handle this in a
more sophisticated way.
There are two ways to enable KCOV; use the compiler that natively
supports -fsanitize-coverage=trace-pc, or build the SANCOV plugin if
the compiler has ability to build GCC plugins. Hence, the correct
dependency for KCOV is:
depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
You do not need to build the SANCOV plugin if the compiler already
supports -fsanitize-coverage=trace-pc. Hence, the select should be:
select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
With this, GCC_PLUGIN_SANCOV is selected only when necessary, so
scripts/Makefile.gcc-plugins can be cleaner.
I also cleaned up Kconfig and scripts/Makefile.kcov as well.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
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This changes security_hook_heads to use hlist_heads instead of
the circular doubly-linked list heads. This should cut down
the size of the struct by about half.
In addition, it allows mutation of the hooks at the tail of the
callback list without having to modify the head. The longer-term
purpose of this is to enable making the heads read only.
Signed-off-by: Sargun Dhillon <sargun@sargun.me>
Reviewed-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: James Morris <james.morris@microsoft.com>
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GCC 8 changed the order of some fields and is very picky about ordering
in static initializers, so instead just move to dynamic initializers,
and drop the redundant already-zero field assignments.
Suggested-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Kees Cook <keescook@chromium.org>
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GCC requires another #include to get the gcc-plugins to build cleanly.
Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Kees Cook <keescook@chromium.org>
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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>
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In the Linux kernel, struct type variables are rarely passed by-value,
and so functions that initialize such variables typically take an input
reference to the variable rather than returning a value that can
subsequently be used in an assignment.
If the initalization function is not part of the same compilation unit,
the lack of an assignment operation defeats any analysis the compiler
can perform as to whether the variable may be used before having been
initialized. This means we may end up passing on such variables
uninitialized, resulting in potential information leaks.
So extend the existing structleak GCC plugin so it will [optionally]
apply to all struct type variables that have their address taken at any
point, rather than only to variables of struct types that have a __user
annotation.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
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This enables the automatic structure selection logic in the randstruct
GCC plugin. The selection logic randomizes all structures that contain
only function pointers, unless marked with __no_randomize_layout.
Signed-off-by: Kees Cook <keescook@chromium.org>
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The NIU ethernet driver intentionally stores a page struct pointer on
top of the "mapping" field. Whitelist this case:
drivers/net/ethernet/sun/niu.c: In function ‘niu_rx_pkt_ignore’:
drivers/net/ethernet/sun/niu.c:3402:10: note: found mismatched ssa struct pointer types: ‘struct page’ and ‘struct address_space’
*link = (struct page *) page->mapping;
~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Kees Cook <keescook@chromium.org>
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The big_key payload structure intentionally stores a struct path in
two void pointers to avoid header soup. Whitelist this case:
security/keys/big_key.c: In function ‘big_key_read’:
security/keys/big_key.c:293:16: note: found mismatched rhs struct pointer types: ‘struct path’ and ‘void *’
struct path *path = (struct path *)&key->payload.data[big_key_path];
^~~~
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
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This is another false positive in bad cast detection:
net/unix/af_unix.c: In function ‘unix_skb_scm_eq’:
net/unix/af_unix.c:1621:31: note: found mismatched rhs struct pointer types: ‘struct unix_skb_parms’ and ‘char’
const struct unix_skb_parms *u = &UNIXCB(skb);
^
UNIXCB is:
#define UNIXCB(skb) (*(struct unix_skb_parms *)&((skb)->cb))
And ->cb is:
char cb[48] __aligned(8);
This is a rather crazy cast, but appears to be safe in the face of
randomization, so whitelist it in the plugin.
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Kees Cook <keescook@chromium.org>
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The LSM initialization routines walk security_hook_heads as an array
of struct list_head instead of via names to avoid a ton of needless
source. Whitelist this to avoid the false positive warning from the
plugin:
security/security.c: In function ‘security_init’:
security/security.c:59:20: note: found mismatched op0 struct pointer types: ‘struct list_head’ and ‘struct security_hook_heads’
struct list_head *list = (struct list_head *) &security_hook_heads;
^
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: James Morris <james.l.morris@oracle.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
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This randstruct plugin is modified from Brad Spengler/PaX Team's code
in the last public patch of grsecurity/PaX based on my understanding
of the code. Changes or omissions from the original code are mine and
don't reflect the original grsecurity/PaX code.
The randstruct GCC plugin randomizes the layout of selected structures
at compile time, as a probabilistic defense against attacks that need to
know the layout of structures within the kernel. This is most useful for
"in-house" kernel builds where neither the randomization seed nor other
build artifacts are made available to an attacker. While less useful for
distribution kernels (where the randomization seed must be exposed for
third party kernel module builds), it still has some value there since now
all kernel builds would need to be tracked by an attacker.
In more performance sensitive scenarios, GCC_PLUGIN_RANDSTRUCT_PERFORMANCE
can be selected to make a best effort to restrict randomization to
cacheline-sized groups of elements, and will not randomize bitfields. This
comes at the cost of reduced randomization.
Two annotations are defined,__randomize_layout and __no_randomize_layout,
which respectively tell the plugin to either randomize or not to
randomize instances of the struct in question. Follow-on patches enable
the auto-detection logic for selecting structures for randomization
that contain only function pointers. It is disabled here to assist with
bisection.
Since any randomized structs must be initialized using designated
initializers, __randomize_layout includes the __designated_init annotation
even when the plugin is disabled so that all builds will require
the needed initialization. (With the plugin enabled, annotations for
automatically chosen structures are marked as well.)
The main differences between this implemenation and grsecurity are:
- disable automatic struct selection (to be enabled in follow-up patch)
- add designated_init attribute at runtime and for manual marking
- clarify debugging output to differentiate bad cast warnings
- add whitelisting infrastructure
- support gcc 7's DECL_ALIGN and DECL_MODE changes (Laura Abbott)
- raise minimum required GCC version to 4.7
Earlier versions of this patch series were ported by Michael Leibowitz.
Signed-off-by: Kees Cook <keescook@chromium.org>
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The c-common.h file moved in stock gcc 4.7, not gcc 4.6. However, most
people building plugins with gcc 4.6 are using the Debian or Ubuntu
version, which includes a patch to move the headers to the 4.7 location.
In case anyone trips over this with a stock gcc 4.6, add a pointer to the
patch used by Debian/Ubuntu.
Signed-off-by: Kees Cook <keescook@chromium.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull gcc-plugins fix from Kees Cook:
"Fixes a typo in sancov plugin, exposed in earlier compiler versions"
* tag 'gcc-plugins-v4.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
gcc-plugins: fix sancov_plugin for gcc-5
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The name of the local variable was inadvertantly changed from
sancov_plugin_pass_info to sancov_pass_info:
scripts/gcc-plugins/sancov_plugin.c: In function ‘int plugin_init(plugin_name_args*, plugin_gcc_version*)’:
scripts/gcc-plugins/sancov_plugin.c:136:67: error: ‘sancov_plugin_pass_info’ was not declared in this scope
This changes the conditional reference to this variable as well.
Fixes: 5a45a4c5c3f5 ("gcc-plugins: consolidate on PASS_INFO macro")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
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This plugin detects any structures that contain __user attributes and
makes sure it is being fully initialized so that a specific class of
information exposure is eliminated. (This plugin was originally designed
to block the exposure of siginfo in CVE-2013-2141.)
Ported from grsecurity/PaX. This version adds a verbose option to the
plugin and the Kconfig.
Signed-off-by: Kees Cook <keescook@chromium.org>
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Now that PASS_INFO() exists, use it in the other existing gcc plugins,
instead of always open coding the same thing.
Based on updates to the grsecurity/PaX gcc plugins.
Signed-off-by: Kees Cook <keescook@chromium.org>
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This updates the GCC plugins gcc-common.h from PaX Team to include
more helpers and header files, specifically adds the PASS_INFO()
macro to make plugin declarations nicer and a helper for proper
const string building.
Signed-off-by: Kees Cook <keescook@chromium.org>
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This updates gcc-common.h from Emese Revfy for gcc 7. This fixes issues seen
by Kugan and Arnd. Build tested with gcc 5.4 and 7 snapshot.
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
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This fixes build errors seen on gcc-4.9.3 or gcc-5.3.1 for an ARM:
arm-soc/init/initramfs.c: In function 'error':
arm-soc/init/initramfs.c:50:1: error: unrecognizable insn:
}
^
(insn 26 25 27 5 (set (reg:SI 111 [ local_entropy.243 ])
(rotatert:SI (reg:SI 116 [ local_entropy.243 ])
(const_int -30 [0xffffffffffffffe2]))) -1
(nil))
Patch from PaX Team <pageexec@freemail.hu>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Brad Spengler <spender@grsecurity.net>
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
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This patch fix spelling typos in printk and kconfig.
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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The stack frame size could grow too large when the plugin used long long
on 32-bit architectures when the given function had too many basic blocks.
The gcc warning was:
drivers/pci/hotplug/ibmphp_ebda.c: In function 'ibmphp_access_ebda':
drivers/pci/hotplug/ibmphp_ebda.c:409:1: warning: the frame size of 1108 bytes is larger than 1024 bytes [-Wframe-larger-than=]
This switches latent_entropy from u64 to unsigned long.
Thanks to PaX Team and Emese Revfy for the patch.
Signed-off-by: Kees Cook <keescook@chromium.org>
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This explicitly exports symbols that gcc expects from plugins.
Based on code from Emese Revfy.
Signed-off-by: Kees Cook <keescook@chromium.org>
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This adds a new gcc plugin named "latent_entropy". It is designed to
extract as much possible uncertainty from a running system at boot time as
possible, hoping to capitalize on any possible variation in CPU operation
(due to runtime data differences, hardware differences, SMP ordering,
thermal timing variation, cache behavior, etc).
At the very least, this plugin is a much more comprehensive example for
how to manipulate kernel code using the gcc plugin internals.
The need for very-early boot entropy tends to be very architecture or
system design specific, so this plugin is more suited for those sorts
of special cases. The existing kernel RNG already attempts to extract
entropy from reliable runtime variation, but this plugin takes the idea to
a logical extreme by permuting a global variable based on any variation
in code execution (e.g. a different value (and permutation function)
is used to permute the global based on loop count, case statement,
if/then/else branching, etc).
To do this, the plugin starts by inserting a local variable in every
marked function. The plugin then adds logic so that the value of this
variable is modified by randomly chosen operations (add, xor and rol) and
random values (gcc generates separate static values for each location at
compile time and also injects the stack pointer at runtime). The resulting
value depends on the control flow path (e.g., loops and branches taken).
Before the function returns, the plugin mixes this local variable into
the latent_entropy global variable. The value of this global variable
is added to the kernel entropy pool in do_one_initcall() and _do_fork(),
though it does not credit any bytes of entropy to the pool; the contents
of the global are just used to mix the pool.
Additionally, the plugin can pre-initialize arrays with build-time
random contents, so that two different kernel builds running on identical
hardware will not have the same starting values.
Signed-off-by: Emese Revfy <re.emese@gmail.com>
[kees: expanded commit message and code comments]
Signed-off-by: Kees Cook <keescook@chromium.org>
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This adds support for building more complex gcc plugins that live in a
subdirectory instead of just in a single source file.
Reported-by: PaX Team <pageexec@freemail.hu>
Signed-off-by: Emese Revfy <re.emese@gmail.com>
[kees: clarified commit message]
Signed-off-by: Kees Cook <keescook@chromium.org>
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There's no reason to repeat the same names in the Makefile when the .so
files have already been listed. The .o list can be generated from them.
Reported-by: PaX Team <pageexec@freemail.hu>
Signed-off-by: Emese Revfy <re.emese@gmail.com>
[kees: clarified commit message]
Signed-off-by: Kees Cook <keescook@chromium.org>
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The sancov gcc plugin inserts a __sanitizer_cov_trace_pc() call
at the start of basic blocks.
This plugin is a helper plugin for the kcov feature. It supports
all gcc versions with plugin support (from gcc-4.5 on).
It is based on the gcc commit "Add fuzzing coverage support" by Dmitry Vyukov
(https://gcc.gnu.org/viewcvs/gcc?limit_changes=0&view=revision&revision=231296).
Signed-off-by: Emese Revfy <re.emese@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Michal Marek <mmarek@suse.com>
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Add a very simple plugin to demonstrate the GCC plugin infrastructure. This GCC
plugin computes the cyclomatic complexity of each function.
The complexity M of a function's control flow graph is defined as:
M = E - N + 2P
where
E = the number of edges
N = the number of nodes
P = the number of connected components (exit nodes).
Signed-off-by: Emese Revfy <re.emese@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Michal Marek <mmarek@suse.com>
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This patch allows to build the whole kernel with GCC plugins. It was ported from
grsecurity/PaX. The infrastructure supports building out-of-tree modules and
building in a separate directory. Cross-compilation is supported too.
Currently the x86, arm, arm64 and uml architectures enable plugins.
The directory of the gcc plugins is scripts/gcc-plugins. You can use a file or a directory
there. The plugins compile with these options:
* -fno-rtti: gcc is compiled with this option so the plugins must use it too
* -fno-exceptions: this is inherited from gcc too
* -fasynchronous-unwind-tables: this is inherited from gcc too
* -ggdb: it is useful for debugging a plugin (better backtrace on internal
errors)
* -Wno-narrowing: to suppress warnings from gcc headers (ipa-utils.h)
* -Wno-unused-variable: to suppress warnings from gcc headers (gcc_version
variable, plugin-version.h)
The infrastructure introduces a new Makefile target called gcc-plugins. It
supports all gcc versions from 4.5 to 6.0. The scripts/gcc-plugin.sh script
chooses the proper host compiler (gcc-4.7 can be built by either gcc or g++).
This script also checks the availability of the included headers in
scripts/gcc-plugins/gcc-common.h.
The gcc-common.h header contains frequently included headers for GCC plugins
and it has a compatibility layer for the supported gcc versions.
The gcc-generate-*-pass.h headers automatically generate the registration
structures for GIMPLE, SIMPLE_IPA, IPA and RTL passes.
Note that 'make clean' keeps the *.so files (only the distclean or mrproper
targets clean all) because they are needed for out-of-tree modules.
Based on work created by the PaX Team.
Signed-off-by: Emese Revfy <re.emese@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Michal Marek <mmarek@suse.com>
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