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
tpm_bios_measurements_open(struct inode * inode,struct file * file)25 static 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_nlink) {
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 } else {
51 put_device(&chip->dev);
52 }
53
54 return err;
55 }
56
tpm_bios_measurements_release(struct inode * inode,struct file * file)57 static int tpm_bios_measurements_release(struct inode *inode,
58 struct file *file)
59 {
60 struct seq_file *seq = file->private_data;
61 struct tpm_chip *chip = seq->private;
62
63 put_device(&chip->dev);
64
65 return seq_release(inode, file);
66 }
67
68 static const struct file_operations tpm_bios_measurements_ops = {
69 .owner = THIS_MODULE,
70 .open = tpm_bios_measurements_open,
71 .read = seq_read,
72 .llseek = seq_lseek,
73 .release = tpm_bios_measurements_release,
74 };
75
tpm_read_log(struct tpm_chip * chip)76 static int tpm_read_log(struct tpm_chip *chip)
77 {
78 int rc;
79
80 if (chip->log.bios_event_log != NULL) {
81 dev_dbg(&chip->dev,
82 "%s: ERROR - event log already initialized\n",
83 __func__);
84 return -EFAULT;
85 }
86
87 rc = tpm_read_log_acpi(chip);
88 if (rc != -ENODEV)
89 return rc;
90
91 rc = tpm_read_log_efi(chip);
92 if (rc != -ENODEV)
93 return rc;
94
95 return tpm_read_log_of(chip);
96 }
97
98 /*
99 * tpm_bios_log_setup() - Read the event log from the firmware
100 * @chip: TPM chip to use.
101 *
102 * If an event log is found then the securityfs files are setup to
103 * export it to userspace, otherwise nothing is done.
104 */
tpm_bios_log_setup(struct tpm_chip * chip)105 void tpm_bios_log_setup(struct tpm_chip *chip)
106 {
107 const char *name = dev_name(&chip->dev);
108 struct dentry *dentry;
109 int log_version;
110 int rc = 0;
111
112 if (chip->flags & TPM_CHIP_FLAG_VIRTUAL)
113 return;
114
115 rc = tpm_read_log(chip);
116 if (rc < 0)
117 return;
118 log_version = rc;
119
120 chip->bios_dir = securityfs_create_dir(name, NULL);
121 /* NOTE: securityfs_create_dir can return ENODEV if securityfs is
122 * compiled out. The caller should ignore the ENODEV return code.
123 */
124 if (IS_ERR(chip->bios_dir))
125 return;
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 dentry =
137 securityfs_create_file("binary_bios_measurements",
138 0440, chip->bios_dir,
139 (void *)&chip->bin_log_seqops,
140 &tpm_bios_measurements_ops);
141 if (IS_ERR(dentry))
142 goto err;
143
144 if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
145
146 chip->ascii_log_seqops.chip = chip;
147 chip->ascii_log_seqops.seqops =
148 &tpm1_ascii_b_measurements_seqops;
149
150 dentry =
151 securityfs_create_file("ascii_bios_measurements",
152 0440, chip->bios_dir,
153 (void *)&chip->ascii_log_seqops,
154 &tpm_bios_measurements_ops);
155 if (IS_ERR(dentry))
156 goto err;
157 }
158
159 return;
160
161 err:
162 tpm_bios_log_teardown(chip);
163 return;
164 }
165
tpm_bios_log_teardown(struct tpm_chip * chip)166 void tpm_bios_log_teardown(struct tpm_chip *chip)
167 {
168 securityfs_remove(chip->bios_dir);
169 }
170