REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1194
Speculative execution is used by processor to avoid having to wait for
data to arrive from memory, or for previous operations to finish, the
processor may speculate as to what will be executed.
If the speculation is incorrect, the speculatively executed instructions
might leave hints such as which memory locations have been brought into
cache. Malicious actors can use the bounds check bypass method (code
gadgets with controlled external inputs) to infer data values that have
been used in speculative operations to reveal secrets which should not
otherwise be accessed.
This commit will focus on the SMI handler(s) registered within the
OpalPasswordSupportLib and insert AsmLfence API to mitigate the bounds
check bypass issue.
For SMI handler SmmOpalPasswordHandler():
Under "case SMM_FUNCTION_SET_OPAL_PASSWORD:",
'&DeviceBuffer->OpalDevicePath' can points to a potential cross boundary
access of the 'CommBuffer' (controlled external inputs) during speculative
execution. This cross boundary access pointer is later passed as parameter
'DevicePath' into function OpalSavePasswordToSmm().
Within function OpalSavePasswordToSmm(), 'DevicePathLen' is an access to
the content in 'DevicePath' and can be inferred by code:
"CompareMem (&List->OpalDevicePath, DevicePath, DevicePathLen)". One can
observe which part of the content within either '&List->OpalDevicePath' or
'DevicePath' was brought into cache to possibly reveal the value of
'DevicePathLen'.
Hence, this commit adds a AsmLfence() after the boundary/range checks of
'CommBuffer' to prevent the speculative execution.
A more detailed explanation of the purpose of commit is under the
'Bounds check bypass mitigation' section of the below link:
https://software.intel.com/security-software-guidance/insights/host-firmware-speculative-execution-side-channel-mitigation
And the document at:
https://software.intel.com/security-software-guidance/api-app/sites/default/files/337879-analyzing-potential-bounds-Check-bypass-vulnerabilities.pdf
Cc: Star Zeng <star.zeng@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Current code not check the CommunicationBuffer size before use it. Attacker can
read beyond the end of the (untrusted) commbuffer into controlled memory. Attacker
can get access outside of valid SMM memory regions. This patch add check before
use it.
bugz: https://bugzilla.tianocore.org/show_bug.cgi?id=198
Cc: Yao Jiewen <jiewen.yao@intel.com>
Cc: Wu Hao <hao.a.wu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Yao Jiewen <jiewen.yao@intel.com>
This patch enhance OPAL password lib SMM communication by using fixed
SMM communication buffer.
Update OPAL password lib to consume EDKII_PI_SMM_COMMUNICATION_REGION_TABLE
as fixed communication buffer for SMM communication.
This is designed to meet Microsoft WSMT table definition on FIXED_COMM_BUFFERS
requirement.
Cc: Eric Dong <eric.dong@intel.com>
Cc: Feng Tian <feng.tian@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>
APIs used to support opal password solution to trig opal command.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>
