drivers/char/tpm/eventlog/common.c

   1 /*
   2  * Copyright (C) 2005, 2012 IBM Corporation
   3  *
   4  * Authors:
   5  *      Kent Yoder <key@linux.vnet.ibm.com>
   6  *      Seiji Munetoh <munetoh@jp.ibm.com>
   7  *      Stefan Berger <stefanb@us.ibm.com>
   8  *      Reiner Sailer <sailer@watson.ibm.com>
   9  *      Kylene Hall <kjhall@us.ibm.com>
  10  *      Nayna Jain <nayna@linux.vnet.ibm.com>
  11  *
  12  * Access to the event log created by a system's firmware / BIOS
  13  *
  14  * This program is free software; you can redistribute it and/or
  15  * modify it under the terms of the GNU General Public License
  16  * as published by the Free Software Foundation; either version
  17  * 2 of the License, or (at your option) any later version.
  18  *
  19  */
  20
  21 #include <linux/seq_file.h>
  22 #include <linux/fs.h>
  23 #include <linux/security.h>
  24 #include <linux/module.h>
  25 #include <linux/tpm_eventlog.h>
  26
  27 #include "../tpm.h"
  28 #include "common.h"
  29
  30 static int tpm_bios_measurements_open(struct inode *inode,
  31                                             struct file *file)
  32 {
  33         int err;
  34         struct seq_file *seq;
  35         struct tpm_chip_seqops *chip_seqops;
  36         const struct seq_operations *seqops;
  37         struct tpm_chip *chip;
  38
  39         inode_lock(inode);
  40         if (!inode->i_private) {
  41                 inode_unlock(inode);
  42                 return -ENODEV;
  43         }
  44         chip_seqops = (struct tpm_chip_seqops *)inode->i_private;
  45         seqops = chip_seqops->seqops;
  46         chip = chip_seqops->chip;
  47         get_device(&chip->dev);
  48         inode_unlock(inode);
  49
  50         /* now register seq file */
  51         err = seq_open(file, seqops);
  52         if (!err) {
  53                 seq = file->private_data;
  54                 seq->private = chip;
  55         }
  56
  57         return err;
  58 }
  59
  60 static int tpm_bios_measurements_release(struct inode *inode,
  61                                          struct file *file)
  62 {
  63         struct seq_file *seq = (struct seq_file *)file->private_data;
  64         struct tpm_chip *chip = (struct tpm_chip *)seq->private;
  65
  66         put_device(&chip->dev);
  67
  68         return seq_release(inode, file);
  69 }
  70
  71 static const struct file_operations tpm_bios_measurements_ops = {
  72         .owner = THIS_MODULE,
  73         .open = tpm_bios_measurements_open,
  74         .read = seq_read,
  75         .llseek = seq_lseek,
  76         .release = tpm_bios_measurements_release,
  77 };
  78
  79 static int tpm_read_log(struct tpm_chip *chip)
  80 {
  81         int rc;
  82
  83         if (chip->log.bios_event_log != NULL) {
  84                 dev_dbg(&chip->dev,
  85                         "%s: ERROR - event log already initialized\n",
  86                         __func__);
  87                 return -EFAULT;
  88         }
  89
  90         rc = tpm_read_log_acpi(chip);
  91         if (rc != -ENODEV)
  92                 return rc;
  93
  94         rc = tpm_read_log_efi(chip);
  95         if (rc != -ENODEV)
  96                 return rc;
  97
  98         return tpm_read_log_of(chip);
  99 }
 100
 101 /*
 102  * tpm_bios_log_setup() - Read the event log from the firmware
 103  * @chip: TPM chip to use.
 104  *
 105  * If an event log is found then the securityfs files are setup to
 106  * export it to userspace, otherwise nothing is done.
 107  *
 108  * Returns -ENODEV if the firmware has no event log or securityfs is not
 109  * supported.
 110  */
 111 int tpm_bios_log_setup(struct tpm_chip *chip)
 112 {
 113         const char *name = dev_name(&chip->dev);
 114         unsigned int cnt;
 115         int log_version;
 116         int rc = 0;
 117
 118         rc = tpm_read_log(chip);
 119         if (rc < 0)
 120                 return rc;
 121         log_version = rc;
 122
 123         cnt = 0;
 124         chip->bios_dir[cnt] = securityfs_create_dir(name, NULL);
 125         /* NOTE: securityfs_create_dir can return ENODEV if securityfs is
 126          * compiled out. The caller should ignore the ENODEV return code.
 127          */
 128         if (IS_ERR(chip->bios_dir[cnt]))
 129                 goto err;
 130         cnt++;
 131
 132         chip->bin_log_seqops.chip = chip;
 133         if (log_version == EFI_TCG2_EVENT_LOG_FORMAT_TCG_2)
 134                 chip->bin_log_seqops.seqops =
 135                         &tpm2_binary_b_measurements_seqops;
 136         else
 137                 chip->bin_log_seqops.seqops =
 138                         &tpm1_binary_b_measurements_seqops;
 139
 140
 141         chip->bios_dir[cnt] =
 142             securityfs_create_file("binary_bios_measurements",
 143                                    0440, chip->bios_dir[0],
 144                                    (void *)&chip->bin_log_seqops,
 145                                    &tpm_bios_measurements_ops);
 146         if (IS_ERR(chip->bios_dir[cnt]))
 147                 goto err;
 148         cnt++;
 149
 150         if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
 151
 152                 chip->ascii_log_seqops.chip = chip;
 153                 chip->ascii_log_seqops.seqops =
 154                         &tpm1_ascii_b_measurements_seqops;
 155
 156                 chip->bios_dir[cnt] =
 157                         securityfs_create_file("ascii_bios_measurements",
 158                                                0440, chip->bios_dir[0],
 159                                                (void *)&chip->ascii_log_seqops,
 160                                                &tpm_bios_measurements_ops);
 161                 if (IS_ERR(chip->bios_dir[cnt]))
 162                         goto err;
 163                 cnt++;
 164         }
 165
 166         return 0;
 167
 168 err:
 169         rc = PTR_ERR(chip->bios_dir[cnt]);
 170         chip->bios_dir[cnt] = NULL;
 171         tpm_bios_log_teardown(chip);
 172         return rc;
 173 }
 174
 175 void tpm_bios_log_teardown(struct tpm_chip *chip)
 176 {
 177         int i;
 178         struct inode *inode;
 179
 180         /* securityfs_remove currently doesn't take care of handling sync
 181          * between removal and opening of pseudo files. To handle this, a
 182          * workaround is added by making i_private = NULL here during removal
 183          * and to check it during open(), both within inode_lock()/unlock().
 184          * This design ensures that open() either safely gets kref or fails.
 185          */
 186         for (i = (TPM_NUM_EVENT_LOG_FILES - 1); i >= 0; i--) {
 187                 if (chip->bios_dir[i]) {
 188                         inode = d_inode(chip->bios_dir[i]);
 189                         inode_lock(inode);
 190                         inode->i_private = NULL;
 191                         inode_unlock(inode);
 192                         securityfs_remove(chip->bios_dir[i]);
 193                 }
 194         }
 195 }