1 /*
2 * Copyright (C) 2005, 2012 IBM Corporation
3 *
4 * Authors:
5 * Kent Yoder <key@linux.vnet.ibm.com>
6 * Seiji Munetoh <munetoh@jp.ibm.com>
7 * Stefan Berger <stefanb@us.ibm.com>
8 * Reiner Sailer <sailer@watson.ibm.com>
9 * Kylene Hall <kjhall@us.ibm.com>
10 * Nayna Jain <nayna@linux.vnet.ibm.com>
11 *
12 * Access to the event log created by a system's firmware / BIOS
13 *
14 * This program is free software; you can redistribute it and/or
15 * modify it under the terms of the GNU General Public License
16 * as published by the Free Software Foundation; either version
17 * 2 of the License, or (at your option) any later version.
18 *
19 */
20
21 #include <linux/seq_file.h>
22 #include <linux/fs.h>
23 #include <linux/security.h>
24 #include <linux/module.h>
25 #include <linux/tpm_eventlog.h>
26
27 #include "../tpm.h"
28 #include "common.h"
29
tpm_bios_measurements_open(struct inode * inode,struct file * file)30 static int tpm_bios_measurements_open(struct inode *inode,
31 struct file *file)
32 {
33 int err;
34 struct seq_file *seq;
35 struct tpm_chip_seqops *chip_seqops;
36 const struct seq_operations *seqops;
37 struct tpm_chip *chip;
38
39 inode_lock(inode);
40 if (!inode->i_private) {
41 inode_unlock(inode);
42 return -ENODEV;
43 }
44 chip_seqops = (struct tpm_chip_seqops *)inode->i_private;
45 seqops = chip_seqops->seqops;
46 chip = chip_seqops->chip;
47 get_device(&chip->dev);
48 inode_unlock(inode);
49
50 /* now register seq file */
51 err = seq_open(file, seqops);
52 if (!err) {
53 seq = file->private_data;
54 seq->private = chip;
55 }
56
57 return err;
58 }
59
tpm_bios_measurements_release(struct inode * inode,struct file * file)60 static int tpm_bios_measurements_release(struct inode *inode,
61 struct file *file)
62 {
63 struct seq_file *seq = (struct seq_file *)file->private_data;
64 struct tpm_chip *chip = (struct tpm_chip *)seq->private;
65
66 put_device(&chip->dev);
67
68 return seq_release(inode, file);
69 }
70
71 static const struct file_operations tpm_bios_measurements_ops = {
72 .owner = THIS_MODULE,
73 .open = tpm_bios_measurements_open,
74 .read = seq_read,
75 .llseek = seq_lseek,
76 .release = tpm_bios_measurements_release,
77 };
78
tpm_read_log(struct tpm_chip * chip)79 static int tpm_read_log(struct tpm_chip *chip)
80 {
81 int rc;
82
83 if (chip->log.bios_event_log != NULL) {
84 dev_dbg(&chip->dev,
85 "%s: ERROR - event log already initialized\n",
86 __func__);
87 return -EFAULT;
88 }
89
90 rc = tpm_read_log_acpi(chip);
91 if (rc != -ENODEV)
92 return rc;
93
94 rc = tpm_read_log_efi(chip);
95 if (rc != -ENODEV)
96 return rc;
97
98 return tpm_read_log_of(chip);
99 }
100
101 /*
102 * tpm_bios_log_setup() - Read the event log from the firmware
103 * @chip: TPM chip to use.
104 *
105 * If an event log is found then the securityfs files are setup to
106 * export it to userspace, otherwise nothing is done.
107 */
tpm_bios_log_setup(struct tpm_chip * chip)108 void tpm_bios_log_setup(struct tpm_chip *chip)
109 {
110 const char *name = dev_name(&chip->dev);
111 unsigned int cnt;
112 int log_version;
113 int rc = 0;
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