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 }
51
52 return err;
53 }
54
tpm_bios_measurements_release(struct inode * inode,struct file * file)55 static 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
66 static 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
tpm_read_log(struct tpm_chip * chip)74 static 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 */
tpm_bios_log_setup(struct tpm_chip * chip)103 void 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
163 err:
164 chip->bios_dir[cnt] = NULL;
165 tpm_bios_log_teardown(chip);
166 return;
167 }
168
tpm_bios_log_teardown(struct tpm_chip * chip)169 void 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