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The NXP Cryptographic Acceleration and Assurance Module (CAAM)
can be used to protect user-defined data across system reboot:
- When the system is fused and boots into secure state, the master
key is a unique never-disclosed device-specific key
- random key is encrypted by key derived from master key
- data is encrypted using the random key
- encrypted data and its encrypted random key are stored alongside
- This blob can now be safely stored in non-volatile memory
On next power-on:
- blob is loaded into CAAM
- CAAM writes decrypted data either into memory or key register
Add functions to realize encrypting and decrypting into memory alongside
the CAAM driver.
They will be used in a later commit as a source for the trusted key
seal/unseal mechanism.
Reviewed-by: David Gstir <david@sigma-star.at>
Reviewed-by: Pankaj Gupta <pankaj.gupta@nxp.com>
Tested-by: Tim Harvey <tharvey@gateworks.com>
Tested-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Tested-by: Pankaj Gupta <pankaj.gupta@nxp.com>
Tested-by: Michael Walle <michael@walle.cc> # on ls1028a (non-E and E)
Tested-by: John Ernberg <john.ernberg@actia.se> # iMX8QXP
Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
104 lines
2.9 KiB
C
104 lines
2.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2020 Pengutronix, Ahmad Fatoum <kernel@pengutronix.de>
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*/
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#ifndef __CAAM_BLOB_GEN
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#define __CAAM_BLOB_GEN
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#include <linux/types.h>
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#include <linux/errno.h>
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#define CAAM_BLOB_KEYMOD_LENGTH 16
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#define CAAM_BLOB_OVERHEAD (32 + 16)
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#define CAAM_BLOB_MAX_LEN 4096
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struct caam_blob_priv;
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/**
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* struct caam_blob_info - information for CAAM blobbing
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* @input: pointer to input buffer (must be DMAable)
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* @input_len: length of @input buffer in bytes.
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* @output: pointer to output buffer (must be DMAable)
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* @output_len: length of @output buffer in bytes.
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* @key_mod: key modifier
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* @key_mod_len: length of @key_mod in bytes.
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* May not exceed %CAAM_BLOB_KEYMOD_LENGTH
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*/
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struct caam_blob_info {
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void *input;
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size_t input_len;
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void *output;
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size_t output_len;
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const void *key_mod;
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size_t key_mod_len;
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};
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/**
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* caam_blob_gen_init - initialize blob generation
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* Return: pointer to new &struct caam_blob_priv instance on success
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* and ``ERR_PTR(-ENODEV)`` if CAAM has no hardware blobbing support
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* or no job ring could be allocated.
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*/
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struct caam_blob_priv *caam_blob_gen_init(void);
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/**
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* caam_blob_gen_exit - free blob generation resources
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* @priv: instance returned by caam_blob_gen_init()
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*/
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void caam_blob_gen_exit(struct caam_blob_priv *priv);
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/**
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* caam_process_blob - encapsulate or decapsulate blob
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* @priv: instance returned by caam_blob_gen_init()
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* @info: pointer to blobbing info describing key, blob and
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* key modifier buffers.
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* @encap: true for encapsulation, false for decapsulation
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*
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* Return: %0 and sets ``info->output_len`` on success and a negative
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* error code otherwise.
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*/
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int caam_process_blob(struct caam_blob_priv *priv,
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struct caam_blob_info *info, bool encap);
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/**
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* caam_encap_blob - encapsulate blob
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* @priv: instance returned by caam_blob_gen_init()
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* @info: pointer to blobbing info describing input key,
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* output blob and key modifier buffers.
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*
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* Return: %0 and sets ``info->output_len`` on success and
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* a negative error code otherwise.
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*/
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static inline int caam_encap_blob(struct caam_blob_priv *priv,
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struct caam_blob_info *info)
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{
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if (info->output_len < info->input_len + CAAM_BLOB_OVERHEAD)
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return -EINVAL;
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return caam_process_blob(priv, info, true);
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}
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/**
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* caam_decap_blob - decapsulate blob
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* @priv: instance returned by caam_blob_gen_init()
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* @info: pointer to blobbing info describing output key,
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* input blob and key modifier buffers.
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*
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* Return: %0 and sets ``info->output_len`` on success and
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* a negative error code otherwise.
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*/
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static inline int caam_decap_blob(struct caam_blob_priv *priv,
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struct caam_blob_info *info)
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{
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if (info->input_len < CAAM_BLOB_OVERHEAD ||
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info->output_len < info->input_len - CAAM_BLOB_OVERHEAD)
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return -EINVAL;
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return caam_process_blob(priv, info, false);
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}
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#endif
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