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afaef01c00
kernel_optimize_test/scripts/gcc-plugins
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Alexander Popov afaef01c00 x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls 
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>
2018-09-04 10:35:47 -07:00
..
.gitignore gcc-plugins: Add the randstruct plugin 2017-06-22 16:15:45 -07:00
cyc_complexity_plugin.c gcc-plugins: consolidate on PASS_INFO macro 2017-01-13 14:20:03 -08:00
gcc-common.h gcc-plugins: Clean up the cgraph_create_edge* macros 2018-07-24 16:14:06 -07:00
gcc-generate-gimple-pass.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
gcc-generate-ipa-pass.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
gcc-generate-rtl-pass.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
gcc-generate-simple_ipa-pass.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
gen-random-seed.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls 2018-09-04 10:35:47 -07:00
latent_entropy_plugin.c gcc-plugins: Use dynamic initializers 2018-02-05 17:27:46 -08:00
Makefile gcc-plugins: remove unused GCC_PLUGIN_SUBDIR 2018-07-02 19:27:00 -07:00
randomize_layout_plugin.c security: convert security hooks to use hlist 2018-03-31 13:18:27 +11:00
sancov_plugin.c gcc-plugins: fix sancov_plugin for gcc-5 2017-02-27 14:10:10 -08:00
structleak_plugin.c gcc-plugins: Use dynamic initializers 2018-02-05 17:27:46 -08:00