980bde5834
During boot we only want to measure things which *must* be verified - this should provide more deterministic ordering. Reviewed by: stevek MFC after: 1 week Sponsored by: Juniper Networks Differential Revision: https://reviews.freebsd.org/D20297
105 lines
2.8 KiB
C
105 lines
2.8 KiB
C
/*-
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* Copyright (c) 2018, Juniper Networks, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "libsecureboot-priv.h"
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/*
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* To support measured boot without putting a ton
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* of extra code in the loader, we just maintain
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* a hash of all the hashes we (attempt to) verify.
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* The loader can export this for kernel or rc script
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* to feed to a TPM pcr register - hence the name ve_pcr.
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*
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* NOTE: in the current standard the TPM pcr register size is for SHA1,
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* the fact that we provide a SHA256 hash should not matter
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* as long as we are consistent - it can be truncated or hashed
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* before feeding to TPM.
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*/
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static const br_hash_class *pcr_md = NULL;
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static br_hash_compat_context pcr_ctx;
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static size_t pcr_hlen = 0;
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static int pcr_updating;
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/**
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* @brief initialize pcr context
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*
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* Real TPM registers only hold a SHA1 hash
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* but we use SHA256
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*/
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void
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ve_pcr_init(void)
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{
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pcr_updating = 0;
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pcr_hlen = br_sha256_SIZE;
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pcr_md = &br_sha256_vtable;
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pcr_md->init(&pcr_ctx.vtable);
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}
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/**
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* @brief get pcr_updating state
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*/
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int
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ve_pcr_updating_get(void)
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{
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return (pcr_updating);
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}
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/**
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* @brief set pcr_updating state
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*/
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void
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ve_pcr_updating_set(int updating)
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{
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pcr_updating = updating;
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}
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/**
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* @brief update pcr context
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*/
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void
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ve_pcr_update(unsigned char *data, size_t dlen)
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{
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if (pcr_updating != 0 && pcr_md != NULL)
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pcr_md->update(&pcr_ctx.vtable, data, dlen);
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}
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/**
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* @brief get pcr result
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*/
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ssize_t
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ve_pcr_get(unsigned char *buf, size_t sz)
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{
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if (!pcr_md)
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return (-1);
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if (sz < pcr_hlen)
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return (-1);
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pcr_md->out(&pcr_ctx.vtable, buf);
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return (pcr_hlen);
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}
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