c46f340569
UEFI systems provide a boot services protocol for obtaining the TPM event log, but this is unusable after ExitBootServices() is called. Unfortunately ExitBootServices() itself triggers additional TPM events that then can't be obtained using this protocol. The platform provides a mechanism for the OS to obtain these events by recording them to a separate UEFI configuration table which the OS can then map. Unfortunately this table isn't self describing in terms of providing its length, so we need to parse the events inside it to figure out how long it is. Since the table isn't mapped at this point, we need to extend the length calculation function to be able to map the event as it goes along. (Fixes by Bartosz Szczepanek <bsz@semihalf.com>) Signed-off-by: Matthew Garrett <mjg59@google.com> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Bartosz Szczepanek <bsz@semihalf.com> Tested-by: Bartosz Szczepanek <bsz@semihalf.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
93 lines
2.2 KiB
C
93 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2017 Google, Inc.
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* Thiebaud Weksteen <tweek@google.com>
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*/
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#define TPM_MEMREMAP(start, size) early_memremap(start, size)
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#define TPM_MEMUNMAP(start, size) early_memunmap(start, size)
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#include <asm/early_ioremap.h>
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#include <linux/efi.h>
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#include <linux/init.h>
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#include <linux/memblock.h>
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#include <linux/tpm_eventlog.h>
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int efi_tpm_final_log_size;
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EXPORT_SYMBOL(efi_tpm_final_log_size);
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static int tpm2_calc_event_log_size(void *data, int count, void *size_info)
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{
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struct tcg_pcr_event2_head *header;
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int event_size, size = 0;
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while (count > 0) {
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header = data + size;
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event_size = __calc_tpm2_event_size(header, size_info, true);
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if (event_size == 0)
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return -1;
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size += event_size;
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count--;
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}
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return size;
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}
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/*
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* Reserve the memory associated with the TPM Event Log configuration table.
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*/
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int __init efi_tpm_eventlog_init(void)
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{
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struct linux_efi_tpm_eventlog *log_tbl;
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struct efi_tcg2_final_events_table *final_tbl;
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unsigned int tbl_size;
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int ret = 0;
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if (efi.tpm_log == EFI_INVALID_TABLE_ADDR) {
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/*
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* We can't calculate the size of the final events without the
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* first entry in the TPM log, so bail here.
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*/
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return 0;
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}
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log_tbl = early_memremap(efi.tpm_log, sizeof(*log_tbl));
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if (!log_tbl) {
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pr_err("Failed to map TPM Event Log table @ 0x%lx\n",
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efi.tpm_log);
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efi.tpm_log = EFI_INVALID_TABLE_ADDR;
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return -ENOMEM;
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}
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tbl_size = sizeof(*log_tbl) + log_tbl->size;
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memblock_reserve(efi.tpm_log, tbl_size);
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if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR)
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goto out;
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final_tbl = early_memremap(efi.tpm_final_log, sizeof(*final_tbl));
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if (!final_tbl) {
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pr_err("Failed to map TPM Final Event Log table @ 0x%lx\n",
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efi.tpm_final_log);
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efi.tpm_final_log = EFI_INVALID_TABLE_ADDR;
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ret = -ENOMEM;
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goto out;
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}
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tbl_size = tpm2_calc_event_log_size((void *)efi.tpm_final_log
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+ sizeof(final_tbl->version)
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+ sizeof(final_tbl->nr_events),
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final_tbl->nr_events,
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log_tbl->log);
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memblock_reserve((unsigned long)final_tbl,
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tbl_size + sizeof(*final_tbl));
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early_memunmap(final_tbl, sizeof(*final_tbl));
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efi_tpm_final_log_size = tbl_size;
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out:
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early_memunmap(log_tbl, sizeof(*log_tbl));
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return ret;
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}
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