Currently, the event log file operations are not serialized with
tpm_chip_unregister(), which can possibly cause a race condition.
This patch fixes the race condition by:
- moving read_log() from fops to chip register.
- disallowing event log file operations when chip unregister is in
progress.
- guarding event log memory using chip krefs.
Suggested-by: Jason Gunthorpe <jguntho...@obsidianresearch.com>
Signed-off-by: Nayna Jain <na...@linux.vnet.ibm.com>
---
drivers/char/tpm/tpm-chip.c | 1 +
drivers/char/tpm/tpm.h | 11 ++++++
drivers/char/tpm/tpm_acpi.c | 12 +++++--
drivers/char/tpm/tpm_eventlog.c | 80 ++++++++++++++++++++++++++---------------
drivers/char/tpm/tpm_eventlog.h | 2 +-
drivers/char/tpm/tpm_of.c | 4 ++-
6 files changed, 76 insertions(+), 34 deletions(-)
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index eac1f10..813e0d7 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -127,6 +127,7 @@ static void tpm_dev_release(struct device *dev)
idr_remove(&dev_nums_idr, chip->dev_num);
mutex_unlock(&idr_lock);
+ kfree(chip->log.bios_event_log);
kfree(chip);
}
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 4c118a4..bfe93e6 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -35,6 +35,8 @@
#include <linux/cdev.h>
#include <linux/highmem.h>
+#include "tpm_eventlog.h"
+
enum tpm_const {
TPM_MINOR = 224, /* officially assigned */
TPM_BUFSIZE = 4096,
@@ -146,6 +148,11 @@ enum tpm_chip_flags {
TPM_CHIP_FLAG_VIRTUAL = BIT(3),
};
+struct tpm_chip_seqops {
+ struct tpm_chip *chip;
+ const struct seq_operations *seqops;
+};
+
struct tpm_chip {
struct device dev;
struct cdev cdev;
@@ -157,6 +164,10 @@ struct tpm_chip {
struct rw_semaphore ops_sem;
const struct tpm_class_ops *ops;
+ struct tpm_bios_log log;
+ struct tpm_chip_seqops bin_log_seqops;
+ struct tpm_chip_seqops ascii_log_seqops;
+
unsigned int flags;
int dev_num; /* /dev/tpm# */
diff --git a/drivers/char/tpm/tpm_acpi.c b/drivers/char/tpm/tpm_acpi.c
index 565a947..4d6c2d7 100644
--- a/drivers/char/tpm/tpm_acpi.c
+++ b/drivers/char/tpm/tpm_acpi.c
@@ -45,13 +45,15 @@ struct acpi_tcpa {
};
/* read binary bios log */
-int read_log(struct tpm_bios_log *log)
+int read_log(struct tpm_chip *chip)
{
struct acpi_tcpa *buff;
acpi_status status;
void __iomem *virt;
u64 len, start;
+ struct tpm_bios_log *log;
+ log = &chip->log;
if (log->bios_event_log != NULL) {
printk(KERN_ERR
"%s: ERROR - Eventlog already initialized\n",
@@ -97,13 +99,17 @@ int read_log(struct tpm_bios_log *log)
virt = acpi_os_map_iomem(start, len);
if (!virt) {
- kfree(log->bios_event_log);
printk("%s: ERROR - Unable to map memory\n", __func__);
- return -EIO;
+ goto err;
}
memcpy_fromio(log->bios_event_log, virt, len);
acpi_os_unmap_iomem(virt, len);
return 0;
+
+err:
+ kfree(log->bios_event_log);
+ return -EIO;
+
}
diff --git a/drivers/char/tpm/tpm_eventlog.c b/drivers/char/tpm/tpm_eventlog.c
index 753e92d..bb142f2 100644
--- a/drivers/char/tpm/tpm_eventlog.c
+++ b/drivers/char/tpm/tpm_eventlog.c
@@ -73,7 +73,8 @@ static const char* tcpa_pc_event_id_strings[] = {
static void *tpm_bios_measurements_start(struct seq_file *m, loff_t *pos)
{
loff_t i;
- struct tpm_bios_log *log = m->private;
+ struct tpm_chip *chip = m->private;
+ struct tpm_bios_log *log = &chip->log;
void *addr = log->bios_event_log;
void *limit = log->bios_event_log_end;
struct tcpa_event *event;
@@ -120,7 +121,8 @@ static void *tpm_bios_measurements_next(struct seq_file *m,
void *v,
loff_t *pos)
{
struct tcpa_event *event = v;
- struct tpm_bios_log *log = m->private;
+ struct tpm_chip *chip = m->private;
+ struct tpm_bios_log *log = &chip->log;
void *limit = log->bios_event_log_end;
u32 converted_event_size;
u32 converted_event_type;
@@ -261,13 +263,10 @@ static int tpm_binary_bios_measurements_show(struct
seq_file *m, void *v)
static int tpm_bios_measurements_release(struct inode *inode,
struct file *file)
{
- struct seq_file *seq = file->private_data;
- struct tpm_bios_log *log = seq->private;
+ struct seq_file *seq = (struct seq_file *)file->private_data;
+ struct tpm_chip *chip = (struct tpm_chip *)seq->private;
- if (log) {
- kfree(log->bios_event_log);
- kfree(log);
- }
+ put_device(&chip->dev);
return seq_release(inode, file);
}
@@ -323,36 +322,34 @@ static int tpm_bios_measurements_open(struct inode *inode,
struct file *file)
{
int err;
- struct tpm_bios_log *log;
struct seq_file *seq;
- const struct seq_operations *seqops =
- (const struct seq_operations *)inode->i_private;
-
- log = kzalloc(sizeof(struct tpm_bios_log), GFP_KERNEL);
- if (!log)
- return -ENOMEM;
-
- if ((err = read_log(log)))
- goto out_free;
+ struct tpm_chip_seqops *chip_seqops;
+ const struct seq_operations *seqops;
+ struct tpm_chip *chip;
+
+ inode_lock(inode);
+ if (!inode->i_private) {
+ inode_unlock(inode);
+ return -ENODEV;
+ }
+ chip_seqops = (struct tpm_chip_seqops *)inode->i_private;
+ seqops = chip_seqops->seqops;
+ chip = chip_seqops->chip;
+ get_device(&chip->dev);
/* now register seq file */
err = seq_open(file, seqops);
if (!err) {
seq = file->private_data;
- seq->private = log;
- } else {
- goto out_free;
+ seq->private = chip;
}
-out:
+ inode_unlock(inode);
return err;
-out_free:
- kfree(log->bios_event_log);
- kfree(log);
- goto out;
}
static const struct file_operations tpm_bios_measurements_ops = {
+ .owner = THIS_MODULE,
.open = tpm_bios_measurements_open,
.read = seq_read,
.llseek = seq_lseek,
@@ -372,10 +369,22 @@ int tpm_bios_log_setup(struct tpm_chip *chip)
{
const char *name = dev_name(&chip->dev);
unsigned int cnt;
+ int rc = 0;
if (chip->flags & TPM_CHIP_FLAG_TPM2)
return 0;
+ rc = read_log(chip);
+ /*
+ * read_log failure means event log is not supported except for ENOMEM
+ */
+ if (rc < 0) {
+ if (rc == -ENOMEM)
+ return rc;
+ else
+ return 0;
+ }
+
cnt = 0;
chip->bios_dir[cnt] =
securityfs_create_dir(name, NULL);
@@ -383,19 +392,25 @@ int tpm_bios_log_setup(struct tpm_chip *chip)
goto err;
cnt++;
+ chip->bin_log_seqops.chip = chip;
+ chip->bin_log_seqops.seqops = &tpm_binary_b_measurments_seqops;
+
chip->bios_dir[cnt] =
securityfs_create_file("binary_bios_measurements",
S_IRUSR | S_IRGRP, chip->bios_dir[0],
- (void *)&tpm_binary_b_measurments_seqops,
+ (void *)&chip->bin_log_seqops,
&tpm_bios_measurements_ops);
if (is_bad(chip->bios_dir[cnt]))
goto err;
cnt++;
+ chip->ascii_log_seqops.chip = chip;
+ chip->ascii_log_seqops.seqops = &tpm_ascii_b_measurments_seqops;
+
chip->bios_dir[cnt] =
securityfs_create_file("ascii_bios_measurements",
S_IRUSR | S_IRGRP, chip->bios_dir[0],
- (void *)&tpm_ascii_b_measurments_seqops,
+ (void *)&chip->ascii_log_seqops,
&tpm_bios_measurements_ops);
if (is_bad(chip->bios_dir[cnt]))
goto err;
@@ -412,7 +427,14 @@ err:
void tpm_bios_log_teardown(struct tpm_chip *chip)
{
int i;
+ struct inode *inode;
- for (i = (TPM_NUM_EVENT_LOG_FILES - 1); i >= 0; i--)
+ for (i = (TPM_NUM_EVENT_LOG_FILES - 1); i >= 0; i--) {
+ inode = d_inode(chip->bios_dir[i]);
+ inode_lock(inode);
+ inode->i_private = NULL;
+ inode_unlock(inode);
securityfs_remove(chip->bios_dir[i]);
+ }
+
}
diff --git a/drivers/char/tpm/tpm_eventlog.h b/drivers/char/tpm/tpm_eventlog.h
index fd3357e..6df2f8e 100644
--- a/drivers/char/tpm/tpm_eventlog.h
+++ b/drivers/char/tpm/tpm_eventlog.h
@@ -73,7 +73,7 @@ enum tcpa_pc_event_ids {
HOST_TABLE_OF_DEVICES,
};
-int read_log(struct tpm_bios_log *log);
+int read_log(struct tpm_chip *chip);
#if defined(CONFIG_TCG_IBMVTPM) || defined(CONFIG_TCG_IBMVTPM_MODULE) || \
defined(CONFIG_ACPI)
diff --git a/drivers/char/tpm/tpm_of.c b/drivers/char/tpm/tpm_of.c
index 570f30c..68d891a 100644
--- a/drivers/char/tpm/tpm_of.c
+++ b/drivers/char/tpm/tpm_of.c
@@ -20,12 +20,14 @@
#include "tpm.h"
#include "tpm_eventlog.h"
-int read_log(struct tpm_bios_log *log)
+int read_log(struct tpm_chip *chip)
{
struct device_node *np;
const u32 *sizep;
const u64 *basep;
+ struct tpm_bios_log *log;
+ log = &chip->log;
if (log->bios_event_log != NULL) {
pr_err("%s: ERROR - Eventlog already initialized\n", __func__);
return -EFAULT;
--
2.5.0
------------------------------------------------------------------------------
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