drivers/char/tpm/eventlog/efi.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2017 Google
   4  *
   5  * Authors:
   6  *      Thiebaud Weksteen <tweek@google.com>
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/efi.h>
  11 #include <linux/tpm_eventlog.h>
  12
  13 #include "../tpm.h"
  14 #include "common.h"
  15
  16 /* read binary bios log from EFI configuration table */
  17 int tpm_read_log_efi(struct tpm_chip *chip)
  18 {
  19
  20         struct efi_tcg2_final_events_table *final_tbl = NULL;
  21         int final_events_log_size = efi_tpm_final_log_size;
  22         struct linux_efi_tpm_eventlog *log_tbl;
  23         struct tpm_bios_log *log;
  24         u32 log_size;
  25         u8 tpm_log_version;
  26         void *tmp;
  27         int ret;
  28
  29         if (!(chip->flags & TPM_CHIP_FLAG_TPM2))
  30                 return -ENODEV;
  31
  32         if (efi.tpm_log == EFI_INVALID_TABLE_ADDR)
  33                 return -ENODEV;
  34
  35         log = &chip->log;
  36
  37         log_tbl = memremap(efi.tpm_log, sizeof(*log_tbl), MEMREMAP_WB);
  38         if (!log_tbl) {
  39                 pr_err("Could not map UEFI TPM log table !\n");
  40                 return -ENOMEM;
  41         }
  42
  43         log_size = log_tbl->size;
  44         memunmap(log_tbl);
  45
  46         if (!log_size) {
  47                 pr_warn("UEFI TPM log area empty\n");
  48                 return -EIO;
  49         }
  50
  51         log_tbl = memremap(efi.tpm_log, sizeof(*log_tbl) + log_size,
  52                            MEMREMAP_WB);
  53         if (!log_tbl) {
  54                 pr_err("Could not map UEFI TPM log table payload!\n");
  55                 return -ENOMEM;
  56         }
  57
  58         /* malloc EventLog space */
  59         log->bios_event_log = devm_kmemdup(&chip->dev, log_tbl->log, log_size, GFP_KERNEL);
  60         if (!log->bios_event_log) {
  61                 ret = -ENOMEM;
  62                 goto out;
  63         }
  64
  65         log->bios_event_log_end = log->bios_event_log + log_size;
  66         tpm_log_version = log_tbl->version;
  67
  68         ret = tpm_log_version;
  69
  70         if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR ||
  71             final_events_log_size == 0 ||
  72             tpm_log_version != EFI_TCG2_EVENT_LOG_FORMAT_TCG_2)
  73                 goto out;
  74
  75         final_tbl = memremap(efi.tpm_final_log,
  76                              sizeof(*final_tbl) + final_events_log_size,
  77                              MEMREMAP_WB);
  78         if (!final_tbl) {
  79                 pr_err("Could not map UEFI TPM final log\n");
  80                 devm_kfree(&chip->dev, log->bios_event_log);
  81                 ret = -ENOMEM;
  82                 goto out;
  83         }
  84
  85         /*
  86          * The 'final events log' size excludes the 'final events preboot log'
  87          * at its beginning.
  88          */
  89         final_events_log_size -= log_tbl->final_events_preboot_size;
  90
  91         /*
  92          * Allocate memory for the 'combined log' where we will append the
  93          * 'final events log' to.
  94          */
  95         tmp = devm_krealloc(&chip->dev, log->bios_event_log,
  96                             log_size + final_events_log_size,
  97                             GFP_KERNEL);
  98         if (!tmp) {
  99                 devm_kfree(&chip->dev, log->bios_event_log);
 100                 ret = -ENOMEM;
 101                 goto out;
 102         }
 103
 104         log->bios_event_log = tmp;
 105
 106         /*
 107          * Append any of the 'final events log' that didn't also end up in the
 108          * 'main log'. Events can be logged in both if events are generated
 109          * between GetEventLog() and ExitBootServices().
 110          */
 111         memcpy((void *)log->bios_event_log + log_size,
 112                final_tbl->events + log_tbl->final_events_preboot_size,
 113                final_events_log_size);
 114         /*
 115          * The size of the 'combined log' is the size of the 'main log' plus
 116          * the size of the 'final events log'.
 117          */
 118         log->bios_event_log_end = log->bios_event_log +
 119                 log_size + final_events_log_size;
 120
 121 out:
 122         memunmap(final_tbl);
 123         memunmap(log_tbl);
 124         return ret;
 125 }