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_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 } 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 unsigned int cnt;
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 cnt = 0;
121 chip->bios_dir[cnt] = securityfs_create_dir(name, NULL);
122 /* NOTE: securityfs_create_dir can return ENODEV if securityfs is
123 * compiled out. The caller should ignore the ENODEV return code.
124 */
125 if (IS_ERR(chip->bios_dir[cnt]))
126 goto err;
127 cnt++;
128
129 chip->bin_log_seqops.chip = chip;
130 if (log_version == EFI_TCG2_EVENT_LOG_FORMAT_TCG_2)
131 chip->bin_log_seqops.seqops =
132 &tpm2_binary_b_measurements_seqops;
133 else
134 chip->bin_log_seqops.seqops =
135 &tpm1_binary_b_measurements_seqops;
136
137
138 chip->bios_dir[cnt] =
139 securityfs_create_file("binary_bios_measurements",
140 0440, chip->bios_dir[0],
141 (void *)&chip->bin_log_seqops,
142 &tpm_bios_measurements_ops);
143 if (IS_ERR(chip->bios_dir[cnt]))
144 goto err;
145 cnt++;
146
147 if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
148
149 chip->ascii_log_seqops.chip = chip;
150 chip->ascii_log_seqops.seqops =
151 &tpm1_ascii_b_measurements_seqops;
152
153 chip->bios_dir[cnt] =
154 securityfs_create_file("ascii_bios_measurements",
155 0440, chip->bios_dir[0],
156 (void *)&chip->ascii_log_seqops,
157 &tpm_bios_measurements_ops);
158 if (IS_ERR(chip->bios_dir[cnt]))
159 goto err;
160 cnt++;
161 }
162
163 return;
164
165 err:
166 chip->bios_dir[cnt] = NULL;
167 tpm_bios_log_teardown(chip);
168 return;
169 }
170
tpm_bios_log_teardown(struct tpm_chip * chip)171 void tpm_bios_log_teardown(struct tpm_chip *chip)
172 {
173 int i;
174 struct inode *inode;
175
176 /* securityfs_remove currently doesn't take care of handling sync
177 * between removal and opening of pseudo files. To handle this, a
178 * workaround is added by making i_private = NULL here during removal
179 * and to check it during open(), both within inode_lock()/unlock().
180 * This design ensures that open() either safely gets kref or fails.
181 */
182 for (i = (TPM_NUM_EVENT_LOG_FILES - 1); i >= 0; i--) {
183 if (chip->bios_dir[i]) {
184 inode = d_inode(chip->bios_dir[i]);
185 inode_lock(inode);
186 inode->i_private = NULL;
187 inode_unlock(inode);
188 securityfs_remove(chip->bios_dir[i]);
189 }
190 }
191 }
192