[RFC,v2,00/20] lib: Rust implementation of SPDM

Message

Alistair Francis Feb. 27, 2025, 3:09 a.m. UTC

Security Protocols and Data Models (SPDM) [1] is used for authentication,
attestation and key exchange. SPDM is generally used over a range of
transports, such as PCIe, MCTP/SMBus/I3C, ATA, SCSI, NVMe or TCP.

From the kernels perspective SPDM is used to authenticate and attest devices.
In this threat model a device is considered untrusted until it can be verified
by the kernel and userspace using SPDM. As such SPDM data is untrusted data
that can be mallicious.

The SPDM specification is also complex, with the 1.2.1 spec being almost 200
pages and the 1.3.0 spec being almost 250 pages long.

As such we have the kernel parsing untrusted responses from a complex
specification, which sounds like a possible exploit vector. This is the type
of place where Rust excels!

This series implements a SPDM requester in Rust.

This is very similar to Lukas' implementation [2]. This series includes patches
and files from Lukas' C SPDM implementation, which isn't in mainline.

This is a standalone series and doesn't depend on Lukas' implementation, although
we do still rely on Lukas' crypto preperation patches, not all of which are
upstream yet.

To help with maintaining compatibility it's designed in a way to match Lukas'
design and the state struct stores the same information, although in a Rust
struct instead of the original C one.

This series doesn't expose the data to userspace (except for a single sysfs
bool) to avoid the debate about how to do that. I'm planning to do that in
the future though.

This series is based on the latest rust-next tree.

This seris depends on the Untrusted abstraction work [4].

This seris also depends on the recent bindgen support for static inlines  [5].

The entire tree can be seen here: https://github.com/alistair23/linux/tree/alistair/spdm-rust

based-on: https://lore.kernel.org/rust-for-linux/[e-mail]/
based-on: https://lore.kernel.org/rust-for-linux/[e-mail]/

1: https://www.dmtf.org/standards/spdm
2: https://lore.kernel.org/all/[e-mail]/
3: https://github.com/l1k/linux/commits/spdm-future/
4: https://lore.kernel.org/rust-for-linux/[e-mail]/
5: https://lore.kernel.org/rust-for-linux/[e-mail]/

v2:
 - Drop support for Rust and C implementations
 - Include patches from Lukas to reduce series deps
 - Large code cleanups based on more testing
 - Support support for authentication

Alistair Francis (12):
  lib: rspdm: Initial commit of Rust SPDM
  lib: rspdm: Support SPDM get_version
  lib: rspdm: Support SPDM get_capabilities
  lib: rspdm: Support SPDM negotiate_algorithms
  lib: rspdm: Support SPDM get_digests
  lib: rspdm: Support SPDM get_certificate
  crypto: asymmetric_keys - Load certificate parsing early in boot
  KEYS: Load keyring and certificates early in boot
  PCI/CMA: Support built in X.509 certificates
  lib: rspdm: Support SPDM certificate validation
  rust: allow extracting the buffer from a CString
  lib: rspdm: Support SPDM challenge

Jonathan Cameron (1):
  PCI/CMA: Authenticate devices on enumeration

Lukas Wunner (7):
  X.509: Make certificate parser public
  X.509: Parse Subject Alternative Name in certificates
  X.509: Move certificate length retrieval into new helper
  certs: Create blacklist keyring earlier
  PCI/CMA: Validate Subject Alternative Name in certificates
  PCI/CMA: Reauthenticate devices on reset and resume
  PCI/CMA: Expose in sysfs whether devices are authenticated

 Documentation/ABI/testing/sysfs-devices-spdm |   31 +
 MAINTAINERS                                  |   14 +
 certs/blacklist.c                            |    4 +-
 certs/system_keyring.c                       |    4 +-
 crypto/asymmetric_keys/asymmetric_type.c     |    2 +-
 crypto/asymmetric_keys/x509_cert_parser.c    |    9 +
 crypto/asymmetric_keys/x509_loader.c         |   38 +-
 crypto/asymmetric_keys/x509_parser.h         |   40 +-
 crypto/asymmetric_keys/x509_public_key.c     |    2 +-
 drivers/pci/Kconfig                          |   13 +
 drivers/pci/Makefile                         |    4 +
 drivers/pci/cma.asn1                         |   41 +
 drivers/pci/cma.c                            |  272 +++++
 drivers/pci/doe.c                            |    5 +-
 drivers/pci/pci-driver.c                     |    1 +
 drivers/pci/pci-sysfs.c                      |    3 +
 drivers/pci/pci.c                            |   12 +-
 drivers/pci/pci.h                            |   15 +
 drivers/pci/pcie/err.c                       |    3 +
 drivers/pci/probe.c                          |    1 +
 drivers/pci/remove.c                         |    1 +
 include/keys/asymmetric-type.h               |    2 +
 include/keys/x509-parser.h                   |   55 +
 include/linux/oid_registry.h                 |    3 +
 include/linux/pci-doe.h                      |    4 +
 include/linux/pci.h                          |   16 +
 include/linux/spdm.h                         |   39 +
 lib/Kconfig                                  |   16 +
 lib/Makefile                                 |    2 +
 lib/rspdm/Makefile                           |   11 +
 lib/rspdm/consts.rs                          |  135 +++
 lib/rspdm/lib.rs                             |  180 +++
 lib/rspdm/req-sysfs.c                        |   97 ++
 lib/rspdm/state.rs                           | 1037 ++++++++++++++++++
 lib/rspdm/sysfs.rs                           |   28 +
 lib/rspdm/validator.rs                       |  489 +++++++++
 rust/bindgen_static_functions                |    5 +
 rust/bindings/bindings_helper.h              |    7 +
 rust/kernel/error.rs                         |    3 +
 rust/kernel/str.rs                           |    5 +
 40 files changed, 2587 insertions(+), 62 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-devices-spdm
 create mode 100644 drivers/pci/cma.asn1
 create mode 100644 drivers/pci/cma.c
 create mode 100644 include/keys/x509-parser.h
 create mode 100644 include/linux/spdm.h
 create mode 100644 lib/rspdm/Makefile
 create mode 100644 lib/rspdm/consts.rs
 create mode 100644 lib/rspdm/lib.rs
 create mode 100644 lib/rspdm/req-sysfs.c
 create mode 100644 lib/rspdm/state.rs
 create mode 100644 lib/rspdm/sysfs.rs
 create mode 100644 lib/rspdm/validator.rs