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 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 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 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 */ 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 } 170 171 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