On Tue, Oct 18, 2016 at 08:49:42PM -0400, Nayna Jain wrote:
> 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 <[email protected]>
> Signed-off-by: Nayna Jain <[email protected]>
I cannot promise yet that I have time to properly review this before
LPC but I'll try to find time to test this and apply to the eventlog
branch.
/Jarkko
> ---
> 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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