lkml.org 
[lkml]   [2019]   [May]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH, RFC 57/62] x86/mktme: Overview of Multi-Key Total Memory Encryption
    Date
    From: Alison Schofield <alison.schofield@intel.com>

    Provide an overview of MKTME on Intel Platforms.

    Signed-off-by: Alison Schofield <alison.schofield@intel.com>
    Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
    ---
    Documentation/x86/mktme/index.rst | 8 +++
    Documentation/x86/mktme/mktme_overview.rst | 57 ++++++++++++++++++++++
    2 files changed, 65 insertions(+)
    create mode 100644 Documentation/x86/mktme/index.rst
    create mode 100644 Documentation/x86/mktme/mktme_overview.rst

    diff --git a/Documentation/x86/mktme/index.rst b/Documentation/x86/mktme/index.rst
    new file mode 100644
    index 000000000000..1614b52dd3e9
    --- /dev/null
    +++ b/Documentation/x86/mktme/index.rst
    @@ -0,0 +1,8 @@
    +
    +=========================================
    +Multi-Key Total Memory Encryption (MKTME)
    +=========================================
    +
    +.. toctree::
    +
    + mktme_overview
    diff --git a/Documentation/x86/mktme/mktme_overview.rst b/Documentation/x86/mktme/mktme_overview.rst
    new file mode 100644
    index 000000000000..59c023965554
    --- /dev/null
    +++ b/Documentation/x86/mktme/mktme_overview.rst
    @@ -0,0 +1,57 @@
    +Overview
    +=========
    +Multi-Key Total Memory Encryption (MKTME)[1] is a technology that
    +allows transparent memory encryption in upcoming Intel platforms.
    +It uses a new instruction (PCONFIG) for key setup and selects a
    +key for individual pages by repurposing physical address bits in
    +the page tables.
    +
    +Support for MKTME is added to the existing kernel keyring subsystem
    +and via a new mprotect_encrypt() system call that can be used by
    +applications to encrypt anonymous memory with keys obtained from
    +the keyring.
    +
    +This architecture supports encrypting both normal, volatile DRAM
    +and persistent memory. However, persistent memory support is
    +not included in the Linux kernel implementation at this time.
    +(We anticipate adding that support next.)
    +
    +Hardware Background
    +===================
    +
    +MKTME is built on top of an existing single-key technology called
    +TME. TME encrypts all system memory using a single key generated
    +by the CPU on every boot of the system. TME provides mitigation
    +against physical attacks, such as physically removing a DIMM or
    +watching memory bus traffic.
    +
    +MKTME enables the use of multiple encryption keys[2], allowing
    +selection of the encryption key per-page using the page tables.
    +Encryption keys are programmed into each memory controller and
    +the same set of keys is available to all entities on the system
    +with access to that memory (all cores, DMA engines, etc...).
    +
    +MKTME inherits many of the mitigations against hardware attacks
    +from TME. Like TME, MKTME does not mitigate vulnerable or
    +malicious operating systems or virtual machine managers. MKTME
    +offers additional mitigations when compared to TME.
    +
    +TME and MKTME use the AES encryption algorithm in the AES-XTS
    +mode. This mode, typically used for block-based storage devices,
    +takes the physical address of the data into account when
    +encrypting each block. This ensures that the effective key is
    +different for each block of memory. Moving encrypted content
    +across physical address results in garbage on read, mitigating
    +block-relocation attacks. This property is the reason many of
    +the discussed attacks require control of a shared physical page
    +to be handed from the victim to the attacker.
    +
    +--
    +1. https://software.intel.com/sites/default/files/managed/a5/16/Multi-Key-Total-Memory-Encryption-Spec.pdf
    +2. The MKTME architecture supports up to 16 bits of KeyIDs, so a
    + maximum of 65535 keys on top of the “TME key” at KeyID-0. The
    + first implementation is expected to support 5 bits, making 63
    + keys available to applications. However, this is not guaranteed.
    + The number of available keys could be reduced if, for instance,
    + additional physical address space is desired over additional
    + KeyIDs.
    --
    2.20.1
    \
     
     \ /
      Last update: 2019-05-08 16:46    [W:3.913 / U:0.020 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site