02 Nov, 2017
1 commit
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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
Reviewed-by: Philippe Ombredanne
Reviewed-by: Thomas Gleixner
Signed-off-by: Greg Kroah-Hartman
23 Jun, 2017
1 commit
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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 4.7Earlier versions of this patch series were ported by Michael Leibowitz.
Signed-off-by: Kees Cook
09 Aug, 2016
2 commits
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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
Signed-off-by: Emese Revfy
[kees: clarified commit message]
Signed-off-by: Kees Cook -
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
Signed-off-by: Emese Revfy
[kees: clarified commit message]
Signed-off-by: Kees Cook
08 Jun, 2016
3 commits
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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
Acked-by: Kees Cook
Signed-off-by: Michal Marek -
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
Acked-by: Kees Cook
Signed-off-by: Michal Marek -
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
Acked-by: Kees Cook
Signed-off-by: Michal Marek