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 } 51 52 return err; 53 } 54 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 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 */ 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 } 168 169 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