This is a revival of the previous patch set submitted by Richard Weinberger: https://lore.kernel.org/linux-integrity/20210614201620.30451-1-richard@xxxxxx/ v3 is here: https://lore.kernel.org/keyrings/20230918141826.8139-1-david@xxxxxxxxxxxxx/ v3 -> v4: - Split changes on MAINTAINERS and documentation into dedicated patches - Use more concise wording in commit messages as suggested by Jarkko Sakkinen v2 -> v3: - Addressed review comments from Jarkko Sakkinen v1 -> v2: - Revive and rebase to latest version - Include review comments from Ahmad Fatoum The Data CoProcessor (DCP) is an IP core built into many NXP SoCs such as i.mx6ull. Similar to the CAAM engine used in more powerful SoCs, DCP can AES- encrypt/decrypt user data using a unique, never-disclosed, device-specific key. Unlike CAAM though, it cannot directly wrap and unwrap blobs in hardware. As DCP offers only the bare minimum feature set and a blob mechanism needs aid from software. A blob in this case is a piece of sensitive data (e.g. a key) that is encrypted and authenticated using the device-specific key so that unwrapping can only be done on the hardware where the blob was wrapped. This patch series adds a DCP based, trusted-key backend and is similar in spirit to the one by Ahmad Fatoum [0] that does the same for CAAM. It is of interest for similar use cases as the CAAM patch set, but for lower end devices, where CAAM is not available. Because constructing and parsing the blob has to happen in software, we needed to decide on a blob format and chose the following: struct dcp_blob_fmt { __u8 fmt_version; __u8 blob_key[AES_KEYSIZE_128]; __u8 nonce[AES_KEYSIZE_128]; __le32 payload_len; __u8 payload[]; } __packed; The `fmt_version` is currently 1. The encrypted key is stored in the payload area. It is AES-128-GCM encrypted using `blob_key` and `nonce`, GCM auth tag is attached at the end of the payload (`payload_len` does not include the size of the auth tag). The `blob_key` itself is encrypted in AES-128-ECB mode by DCP using the OTP or UNIQUE device key. A new `blob_key` and `nonce` are generated randomly, when sealing/exporting the DCP blob. This patchset was tested with dm-crypt on an i.MX6ULL board. [0] https://lore.kernel.org/keyrings/20220513145705.2080323-1-a.fatoum@xxxxxxxxxxxxxx/ David Gstir (5): crypto: mxs-dcp: Add support for hardware-bound keys KEYS: trusted: Introduce NXP DCP-backed trusted keys MAINTAINERS: add entry for DCP-based trusted keys docs: document DCP-backed trusted keys kernel params docs: trusted-encrypted: add DCP as new trust source .../admin-guide/kernel-parameters.txt | 13 + .../security/keys/trusted-encrypted.rst | 85 +++++ MAINTAINERS | 9 + drivers/crypto/mxs-dcp.c | 104 +++++- include/keys/trusted_dcp.h | 11 + include/soc/fsl/dcp.h | 17 + security/keys/trusted-keys/Kconfig | 9 +- security/keys/trusted-keys/Makefile | 2 + security/keys/trusted-keys/trusted_core.c | 6 +- security/keys/trusted-keys/trusted_dcp.c | 311 ++++++++++++++++++ 10 files changed, 554 insertions(+), 13 deletions(-) create mode 100644 include/keys/trusted_dcp.h create mode 100644 include/soc/fsl/dcp.h create mode 100644 security/keys/trusted-keys/trusted_dcp.c -- 2.35.3
