cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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common.c (4478B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Copyright (C) 2005, 2012 IBM Corporation
      4 *
      5 * Authors:
      6 *	Kent Yoder <key@linux.vnet.ibm.com>
      7 *	Seiji Munetoh <munetoh@jp.ibm.com>
      8 *	Stefan Berger <stefanb@us.ibm.com>
      9 *	Reiner Sailer <sailer@watson.ibm.com>
     10 *	Kylene Hall <kjhall@us.ibm.com>
     11 *	Nayna Jain <nayna@linux.vnet.ibm.com>
     12 *
     13 * Access to the event log created by a system's firmware / BIOS
     14 */
     15
     16#include <linux/seq_file.h>
     17#include <linux/fs.h>
     18#include <linux/security.h>
     19#include <linux/module.h>
     20#include <linux/tpm_eventlog.h>
     21
     22#include "../tpm.h"
     23#include "common.h"
     24
     25static int tpm_bios_measurements_open(struct inode *inode,
     26					    struct file *file)
     27{
     28	int err;
     29	struct seq_file *seq;
     30	struct tpm_chip_seqops *chip_seqops;
     31	const struct seq_operations *seqops;
     32	struct tpm_chip *chip;
     33
     34	inode_lock(inode);
     35	if (!inode->i_private) {
     36		inode_unlock(inode);
     37		return -ENODEV;
     38	}
     39	chip_seqops = (struct tpm_chip_seqops *)inode->i_private;
     40	seqops = chip_seqops->seqops;
     41	chip = chip_seqops->chip;
     42	get_device(&chip->dev);
     43	inode_unlock(inode);
     44
     45	/* now register seq file */
     46	err = seq_open(file, seqops);
     47	if (!err) {
     48		seq = file->private_data;
     49		seq->private = chip;
     50	}
     51
     52	return err;
     53}
     54
     55static int tpm_bios_measurements_release(struct inode *inode,
     56					 struct file *file)
     57{
     58	struct seq_file *seq = (struct seq_file *)file->private_data;
     59	struct tpm_chip *chip = (struct tpm_chip *)seq->private;
     60
     61	put_device(&chip->dev);
     62
     63	return seq_release(inode, file);
     64}
     65
     66static const struct file_operations tpm_bios_measurements_ops = {
     67	.owner = THIS_MODULE,
     68	.open = tpm_bios_measurements_open,
     69	.read = seq_read,
     70	.llseek = seq_lseek,
     71	.release = tpm_bios_measurements_release,
     72};
     73
     74static int tpm_read_log(struct tpm_chip *chip)
     75{
     76	int rc;
     77
     78	if (chip->log.bios_event_log != NULL) {
     79		dev_dbg(&chip->dev,
     80			"%s: ERROR - event log already initialized\n",
     81			__func__);
     82		return -EFAULT;
     83	}
     84
     85	rc = tpm_read_log_acpi(chip);
     86	if (rc != -ENODEV)
     87		return rc;
     88
     89	rc = tpm_read_log_efi(chip);
     90	if (rc != -ENODEV)
     91		return rc;
     92
     93	return tpm_read_log_of(chip);
     94}
     95
     96/*
     97 * tpm_bios_log_setup() - Read the event log from the firmware
     98 * @chip: TPM chip to use.
     99 *
    100 * If an event log is found then the securityfs files are setup to
    101 * export it to userspace, otherwise nothing is done.
    102 */
    103void tpm_bios_log_setup(struct tpm_chip *chip)
    104{
    105	const char *name = dev_name(&chip->dev);
    106	unsigned int cnt;
    107	int log_version;
    108	int rc = 0;
    109
    110	if (chip->flags & TPM_CHIP_FLAG_VIRTUAL)
    111		return;
    112
    113	rc = tpm_read_log(chip);
    114	if (rc < 0)
    115		return;
    116	log_version = rc;
    117
    118	cnt = 0;
    119	chip->bios_dir[cnt] = securityfs_create_dir(name, NULL);
    120	/* NOTE: securityfs_create_dir can return ENODEV if securityfs is
    121	 * compiled out. The caller should ignore the ENODEV return code.
    122	 */
    123	if (IS_ERR(chip->bios_dir[cnt]))
    124		goto err;
    125	cnt++;
    126
    127	chip->bin_log_seqops.chip = chip;
    128	if (log_version == EFI_TCG2_EVENT_LOG_FORMAT_TCG_2)
    129		chip->bin_log_seqops.seqops =
    130			&tpm2_binary_b_measurements_seqops;
    131	else
    132		chip->bin_log_seqops.seqops =
    133			&tpm1_binary_b_measurements_seqops;
    134
    135
    136	chip->bios_dir[cnt] =
    137	    securityfs_create_file("binary_bios_measurements",
    138				   0440, chip->bios_dir[0],
    139				   (void *)&chip->bin_log_seqops,
    140				   &tpm_bios_measurements_ops);
    141	if (IS_ERR(chip->bios_dir[cnt]))
    142		goto err;
    143	cnt++;
    144
    145	if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
    146
    147		chip->ascii_log_seqops.chip = chip;
    148		chip->ascii_log_seqops.seqops =
    149			&tpm1_ascii_b_measurements_seqops;
    150
    151		chip->bios_dir[cnt] =
    152			securityfs_create_file("ascii_bios_measurements",
    153					       0440, chip->bios_dir[0],
    154					       (void *)&chip->ascii_log_seqops,
    155					       &tpm_bios_measurements_ops);
    156		if (IS_ERR(chip->bios_dir[cnt]))
    157			goto err;
    158		cnt++;
    159	}
    160
    161	return;
    162
    163err:
    164	chip->bios_dir[cnt] = NULL;
    165	tpm_bios_log_teardown(chip);
    166	return;
    167}
    168
    169void tpm_bios_log_teardown(struct tpm_chip *chip)
    170{
    171	int i;
    172	struct inode *inode;
    173
    174	/* securityfs_remove currently doesn't take care of handling sync
    175	 * between removal and opening of pseudo files. To handle this, a
    176	 * workaround is added by making i_private = NULL here during removal
    177	 * and to check it during open(), both within inode_lock()/unlock().
    178	 * This design ensures that open() either safely gets kref or fails.
    179	 */
    180	for (i = (TPM_NUM_EVENT_LOG_FILES - 1); i >= 0; i--) {
    181		if (chip->bios_dir[i]) {
    182			inode = d_inode(chip->bios_dir[i]);
    183			inode_lock(inode);
    184			inode->i_private = NULL;
    185			inode_unlock(inode);
    186			securityfs_remove(chip->bios_dir[i]);
    187		}
    188	}
    189}