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 = 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 = file->private_data;
59	struct tpm_chip *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}
190