drivers/char/tpm/tpm_eventlog_efi.c

   1 /*
   2  * Copyright (C) 2017 Google
   3  *
   4  * Authors:
   5  *      Thiebaud Weksteen <tweek@google.com>
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version
  10  * 2 of the License, or (at your option) any later version.
  11  *
  12  */
  13
  14 #include <linux/efi.h>
  15 #include <linux/tpm_eventlog.h>
  16
  17 #include "tpm.h"
  18
  19 /* read binary bios log from EFI configuration table */
  20 int tpm_read_log_efi(struct tpm_chip *chip)
  21 {
  22
  23         struct linux_efi_tpm_eventlog *log_tbl;
  24         struct tpm_bios_log *log;
  25         u32 log_size;
  26         u8 tpm_log_version;
  27
  28         if (!(chip->flags & TPM_CHIP_FLAG_TPM2))
  29                 return -ENODEV;
  30
  31         if (efi.tpm_log == EFI_INVALID_TABLE_ADDR)
  32                 return -ENODEV;
  33
  34         log = &chip->log;
  35
  36         log_tbl = memremap(efi.tpm_log, sizeof(*log_tbl), MEMREMAP_WB);
  37         if (!log_tbl) {
  38                 pr_err("Could not map UEFI TPM log table !\n");
  39                 return -ENOMEM;
  40         }
  41
  42         log_size = log_tbl->size;
  43         memunmap(log_tbl);
  44
  45         log_tbl = memremap(efi.tpm_log, sizeof(*log_tbl) + log_size,
  46                            MEMREMAP_WB);
  47         if (!log_tbl) {
  48                 pr_err("Could not map UEFI TPM log table payload!\n");
  49                 return -ENOMEM;
  50         }
  51
  52         /* malloc EventLog space */
  53         log->bios_event_log = kmalloc(log_size, GFP_KERNEL);
  54         if (!log->bios_event_log)
  55                 goto err_memunmap;
  56         memcpy(log->bios_event_log, log_tbl->log, log_size);
  57         log->bios_event_log_end = log->bios_event_log + log_size;
  58
  59         tpm_log_version = log_tbl->version;
  60         memunmap(log_tbl);
  61         return tpm_log_version;
  62
  63 err_memunmap:
  64         memunmap(log_tbl);
  65         return -ENOMEM;
  66 }