drivers/char/tpm/eventlog/tpm2.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2016 IBM Corporation
   4  *
   5  * Authors:
   6  *      Nayna Jain <nayna@linux.vnet.ibm.com>
   7  *
   8  * Access to TPM 2.0 event log as written by Firmware.
   9  * It assumes that writer of event log has followed TCG Specification
  10  * for Family "2.0" and written the event data in little endian.
  11  * With that, it doesn't need any endian conversion for structure
  12  * content.
  13  */
  14
  15 #include <linux/seq_file.h>
  16 #include <linux/fs.h>
  17 #include <linux/security.h>
  18 #include <linux/module.h>
  19 #include <linux/slab.h>
  20 #include <linux/tpm_eventlog.h>
  21
  22 #include "../tpm.h"
  23 #include "common.h"
  24
  25 /*
  26  * calc_tpm2_event_size() - calculate the event size, where event
  27  * is an entry in the TPM 2.0 event log. The event is of type Crypto
  28  * Agile Log Entry Format as defined in TCG EFI Protocol Specification
  29  * Family "2.0".
  30
  31  * @event: event whose size is to be calculated.
  32  * @event_header: the first event in the event log.
  33  *
  34  * Returns size of the event. If it is an invalid event, returns 0.
  35  */
  36 static size_t calc_tpm2_event_size(struct tcg_pcr_event2_head *event,
  37                                    struct tcg_pcr_event *event_header)
  38 {
  39         return __calc_tpm2_event_size(event, event_header, false);
  40 }
  41
  42 static void *tpm2_bios_measurements_start(struct seq_file *m, loff_t *pos)
  43 {
  44         struct tpm_chip *chip = m->private;
  45         struct tpm_bios_log *log = &chip->log;
  46         void *addr = log->bios_event_log;
  47         void *limit = log->bios_event_log_end;
  48         struct tcg_pcr_event *event_header;
  49         struct tcg_pcr_event2_head *event;
  50         size_t size;
  51         int i;
  52
  53         event_header = addr;
  54         size = struct_size(event_header, event, event_header->event_size);
  55
  56         if (*pos == 0) {
  57                 if (addr + size < limit) {
  58                         if ((event_header->event_type == 0) &&
  59                             (event_header->event_size == 0))
  60                                 return NULL;
  61                         return SEQ_START_TOKEN;
  62                 }
  63         }
  64
  65         if (*pos > 0) {
  66                 addr += size;
  67                 event = addr;
  68                 size = calc_tpm2_event_size(event, event_header);
  69                 if ((addr + size >=  limit) || (size == 0))
  70                         return NULL;
  71         }
  72
  73         for (i = 0; i < (*pos - 1); i++) {
  74                 event = addr;
  75                 size = calc_tpm2_event_size(event, event_header);
  76
  77                 if ((addr + size >= limit) || (size == 0))
  78                         return NULL;
  79                 addr += size;
  80         }
  81
  82         return addr;
  83 }
  84
  85 static void *tpm2_bios_measurements_next(struct seq_file *m, void *v,
  86                                          loff_t *pos)
  87 {
  88         struct tcg_pcr_event *event_header;
  89         struct tcg_pcr_event2_head *event;
  90         struct tpm_chip *chip = m->private;
  91         struct tpm_bios_log *log = &chip->log;
  92         void *limit = log->bios_event_log_end;
  93         size_t event_size;
  94         void *marker;
  95
  96         (*pos)++;
  97         event_header = log->bios_event_log;
  98
  99         if (v == SEQ_START_TOKEN) {
 100                 event_size = struct_size(event_header, event,
 101                                          event_header->event_size);
 102                 marker = event_header;
 103         } else {
 104                 event = v;
 105                 event_size = calc_tpm2_event_size(event, event_header);
 106                 if (event_size == 0)
 107                         return NULL;
 108                 marker = event;
 109         }
 110
 111         marker = marker + event_size;
 112         if (marker >= limit)
 113                 return NULL;
 114         v = marker;
 115         event = v;
 116
 117         event_size = calc_tpm2_event_size(event, event_header);
 118         if (((v + event_size) >= limit) || (event_size == 0))
 119                 return NULL;
 120
 121         return v;
 122 }
 123
 124 static void tpm2_bios_measurements_stop(struct seq_file *m, void *v)
 125 {
 126 }
 127
 128 static int tpm2_binary_bios_measurements_show(struct seq_file *m, void *v)
 129 {
 130         struct tpm_chip *chip = m->private;
 131         struct tpm_bios_log *log = &chip->log;
 132         struct tcg_pcr_event *event_header = log->bios_event_log;
 133         struct tcg_pcr_event2_head *event = v;
 134         void *temp_ptr;
 135         size_t size;
 136
 137         if (v == SEQ_START_TOKEN) {
 138                 size = struct_size(event_header, event,
 139                                    event_header->event_size);
 140                 temp_ptr = event_header;
 141
 142                 if (size > 0)
 143                         seq_write(m, temp_ptr, size);
 144         } else {
 145                 size = calc_tpm2_event_size(event, event_header);
 146                 temp_ptr = event;
 147                 if (size > 0)
 148                         seq_write(m, temp_ptr, size);
 149         }
 150
 151         return 0;
 152 }
 153
 154 const struct seq_operations tpm2_binary_b_measurements_seqops = {
 155         .start = tpm2_bios_measurements_start,
 156         .next = tpm2_bios_measurements_next,
 157         .stop = tpm2_bios_measurements_stop,
 158         .show = tpm2_binary_bios_measurements_show,
 159 };