From: Daniel Axtens <dja@axtens.net>
To: linuxppc-dev@lists.ozlabs.org
Cc: dja@axtens.net, cmr@informatik.wtf, spoorts2@in.ibm.com,
npiggin@gmail.com
Subject: [PATCH 0/7] CVE-2020-4788: Speculation on incompletely validated data on IBM Power9
Date: Fri, 20 Nov 2020 10:13:26 +1100 [thread overview]
Message-ID: <20201119231333.361771-1-dja@axtens.net> (raw)
IBM Power9 processors can speculatively operate on data in the L1
cache before it has been completely validated, via a way-prediction
mechanism. It is not possible for an attacker to determine the
contents of impermissible memory using this method, since these
systems implement a combination of hardware and software security
measures to prevent scenarios where protected data could be leaked.
However these measures don't address the scenario where an attacker
induces the operating system to speculatively execute instructions
using data that the attacker controls. This can be used for example to
speculatively bypass "kernel user access prevention" techniques, as
discovered by Anthony Steinhauser of Google's Safeside Project. This
is not an attack by itself, but there is a possibility it could be
used in conjunction with side-channels or other weaknesses in the
privileged code to construct an attack.
This issue can be mitigated by flushing the L1 cache between privilege
boundaries of concern. This series flushes the cache on kernel entry and
after kernel user accesses.
Thanks to Nick Piggin, Russell Currey, Christopher M. Riedl, Michael
Ellerman and Spoorthy S for their work in developing, optimising,
testing and backporting these fixes, and to the many others who helped
behind the scenes.
Daniel Axtens (3):
selftests/powerpc: entry flush test
selftests/powerpc: refactor entry and rfi_flush tests
powerpc/64s: rename pnv|pseries_setup_rfi_flush to
_setup_security_mitigations
Michael Ellerman (1):
powerpc: Only include kup-radix.h for 64-bit Book3S
Nicholas Piggin (2):
powerpc/64s: flush L1D on kernel entry
powerpc/64s: flush L1D after user accesses
Russell Currey (1):
selftests/powerpc: rfi_flush: disable entry flush if present
.../admin-guide/kernel-parameters.txt | 7 +
.../powerpc/include/asm/book3s/64/kup-radix.h | 66 ++++++---
arch/powerpc/include/asm/exception-64s.h | 12 +-
arch/powerpc/include/asm/feature-fixups.h | 19 +++
arch/powerpc/include/asm/kup.h | 26 +++-
arch/powerpc/include/asm/security_features.h | 7 +
arch/powerpc/include/asm/setup.h | 4 +
arch/powerpc/kernel/exceptions-64s.S | 80 +++++-----
arch/powerpc/kernel/setup_64.c | 122 ++++++++++++++-
arch/powerpc/kernel/syscall_64.c | 2 +-
arch/powerpc/kernel/vmlinux.lds.S | 14 ++
arch/powerpc/lib/feature-fixups.c | 104 +++++++++++++
arch/powerpc/platforms/powernv/setup.c | 24 ++-
arch/powerpc/platforms/pseries/mobility.c | 4 +-
arch/powerpc/platforms/pseries/pseries.h | 2 +-
arch/powerpc/platforms/pseries/setup.c | 15 +-
.../testing/selftests/powerpc/include/utils.h | 5 +
.../selftests/powerpc/security/.gitignore | 1 +
.../selftests/powerpc/security/Makefile | 4 +-
.../selftests/powerpc/security/entry_flush.c | 139 ++++++++++++++++++
.../selftests/powerpc/security/flush_utils.c | 70 +++++++++
.../selftests/powerpc/security/flush_utils.h | 17 +++
.../selftests/powerpc/security/rfi_flush.c | 96 ++++--------
23 files changed, 693 insertions(+), 147 deletions(-)
create mode 100644 tools/testing/selftests/powerpc/security/entry_flush.c
create mode 100644 tools/testing/selftests/powerpc/security/flush_utils.c
create mode 100644 tools/testing/selftests/powerpc/security/flush_utils.h
--
2.25.1
next reply other threads:[~2020-11-19 23:15 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-19 23:13 Daniel Axtens [this message]
2020-11-19 23:13 ` [PATCH 1/7] selftests/powerpc: rfi_flush: disable entry flush if present Daniel Axtens
2020-11-19 23:13 ` [PATCH 2/7] powerpc/64s: flush L1D on kernel entry Daniel Axtens
2020-11-19 23:13 ` [PATCH 3/7] powerpc/64s: flush L1D after user accesses Daniel Axtens
2020-12-03 17:17 ` Qian Cai
2020-12-03 17:31 ` Qian Cai
2020-12-03 18:50 ` Qian Cai
2020-12-04 6:21 ` Christophe Leroy
2020-11-19 23:13 ` [PATCH 4/7] powerpc: Only include kup-radix.h for 64-bit Book3S Daniel Axtens
2020-11-19 23:13 ` [PATCH 5/7] selftests/powerpc: entry flush test Daniel Axtens
2020-11-19 23:13 ` [PATCH 6/7] selftests/powerpc: refactor entry and rfi_flush tests Daniel Axtens
2020-11-19 23:13 ` [PATCH 7/7] powerpc/64s: rename pnv|pseries_setup_rfi_flush to _setup_security_mitigations Daniel Axtens
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