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Date: Tue, 29 May 2018 12:37:28 +0800
From: YaoJun <yaojun8558363@...il.com>
To: kernel-hardening@...ts.openwall.com
Cc: linux-kernel@...r.kernel.org,
linux-security-module@...r.kernel.org,
jmorris@...ei.org
Subject: [PATCH 0/4] migrate swapper_pg_dir
Because the offset between swapper_pg_dir and _text is fixed, when
attackers break KASLR, they can calculate the address of swapper_pg_dir,
and then they can apply KSMA(Kernel Space Mirror Attack). The principle
of KSMA is to insert an entry to PGD, and this entry has type of block
with AP = 01, so attackers can read/write kernel memory directly. Details
can reference:
https://www.blackhat.com/docs/asia-18/asia-18-WANG-KSMA-Breaking-Android-kernel-isolation-and-Rooting-with-ARM-MMU-features.pdf
These patches migrate swapper_pg_dir to new place, and there is no
relationship between swapper_pg_dir and _text. Because this is done
during kernel booting, the physical address of new swapper_pg_dir may
be fixed. Do we need to further randomize it?
YaoJun (4):
Introduce a variable to record physical address of swapper_pg_dir.
Introduce a variable to record new virtual address of swapper_pg_dir.
Make tramp_pg_dir and swapper_pg_dir adjacent
Migrate swapper_pg_dir and tramp_pg_dir.
arch/arm64/include/asm/mmu_context.h | 6 +--
arch/arm64/include/asm/pgtable.h | 2 +
arch/arm64/kernel/cpufeature.c | 2 +-
arch/arm64/kernel/entry.S | 4 +-
arch/arm64/kernel/head.S | 10 ++--
arch/arm64/kernel/hibernate.c | 2 +-
arch/arm64/kernel/sleep.S | 2 +
arch/arm64/kernel/vmlinux.lds.S | 10 ++--
arch/arm64/mm/kasan_init.c | 6 +--
arch/arm64/mm/mmu.c | 72 +++++++++++++++++++---------
10 files changed, 74 insertions(+), 42 deletions(-)
--
2.17.0
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