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
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.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