mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 01:10:04 +00:00
![Jason Gunthorpe](/assets/img/avatar_default.png)
For a long time the cdev read/write interface had this strange idea that userspace had to read the result within 60 seconds otherwise it is discarded. Perhaps this made sense under some older locking regime, but in the modern kernel it is not required and is just dangerous. Since something may be relying on this, double the timeout and print a warning. We can remove the code in a few years, but this should be enough to prevent new users. Suggested-by: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
193 lines
4.7 KiB
C
193 lines
4.7 KiB
C
/*
|
|
* Copyright (C) 2004 IBM Corporation
|
|
* Authors:
|
|
* Leendert van Doorn <leendert@watson.ibm.com>
|
|
* Dave Safford <safford@watson.ibm.com>
|
|
* Reiner Sailer <sailer@watson.ibm.com>
|
|
* Kylene Hall <kjhall@us.ibm.com>
|
|
*
|
|
* Copyright (C) 2013 Obsidian Research Corp
|
|
* Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
|
|
*
|
|
* Device file system interface to the TPM
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License as
|
|
* published by the Free Software Foundation, version 2 of the
|
|
* License.
|
|
*
|
|
*/
|
|
#include <linux/slab.h>
|
|
#include <linux/uaccess.h>
|
|
#include "tpm.h"
|
|
|
|
struct file_priv {
|
|
struct tpm_chip *chip;
|
|
|
|
/* Data passed to and from the tpm via the read/write calls */
|
|
atomic_t data_pending;
|
|
struct mutex buffer_mutex;
|
|
|
|
struct timer_list user_read_timer; /* user needs to claim result */
|
|
struct work_struct work;
|
|
|
|
u8 data_buffer[TPM_BUFSIZE];
|
|
};
|
|
|
|
static void user_reader_timeout(unsigned long ptr)
|
|
{
|
|
struct file_priv *priv = (struct file_priv *)ptr;
|
|
|
|
pr_warn("TPM user space timeout is deprecated (pid=%d)\n",
|
|
task_tgid_nr(current));
|
|
|
|
schedule_work(&priv->work);
|
|
}
|
|
|
|
static void timeout_work(struct work_struct *work)
|
|
{
|
|
struct file_priv *priv = container_of(work, struct file_priv, work);
|
|
|
|
mutex_lock(&priv->buffer_mutex);
|
|
atomic_set(&priv->data_pending, 0);
|
|
memset(priv->data_buffer, 0, sizeof(priv->data_buffer));
|
|
mutex_unlock(&priv->buffer_mutex);
|
|
}
|
|
|
|
static int tpm_open(struct inode *inode, struct file *file)
|
|
{
|
|
struct tpm_chip *chip =
|
|
container_of(inode->i_cdev, struct tpm_chip, cdev);
|
|
struct file_priv *priv;
|
|
|
|
/* It's assured that the chip will be opened just once,
|
|
* by the check of is_open variable, which is protected
|
|
* by driver_lock. */
|
|
if (test_and_set_bit(0, &chip->is_open)) {
|
|
dev_dbg(&chip->dev, "Another process owns this TPM\n");
|
|
return -EBUSY;
|
|
}
|
|
|
|
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
|
|
if (priv == NULL) {
|
|
clear_bit(0, &chip->is_open);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
priv->chip = chip;
|
|
atomic_set(&priv->data_pending, 0);
|
|
mutex_init(&priv->buffer_mutex);
|
|
setup_timer(&priv->user_read_timer, user_reader_timeout,
|
|
(unsigned long)priv);
|
|
INIT_WORK(&priv->work, timeout_work);
|
|
|
|
file->private_data = priv;
|
|
return 0;
|
|
}
|
|
|
|
static ssize_t tpm_read(struct file *file, char __user *buf,
|
|
size_t size, loff_t *off)
|
|
{
|
|
struct file_priv *priv = file->private_data;
|
|
ssize_t ret_size;
|
|
int rc;
|
|
|
|
del_singleshot_timer_sync(&priv->user_read_timer);
|
|
flush_work(&priv->work);
|
|
ret_size = atomic_read(&priv->data_pending);
|
|
if (ret_size > 0) { /* relay data */
|
|
ssize_t orig_ret_size = ret_size;
|
|
if (size < ret_size)
|
|
ret_size = size;
|
|
|
|
mutex_lock(&priv->buffer_mutex);
|
|
rc = copy_to_user(buf, priv->data_buffer, ret_size);
|
|
memset(priv->data_buffer, 0, orig_ret_size);
|
|
if (rc)
|
|
ret_size = -EFAULT;
|
|
|
|
mutex_unlock(&priv->buffer_mutex);
|
|
}
|
|
|
|
atomic_set(&priv->data_pending, 0);
|
|
|
|
return ret_size;
|
|
}
|
|
|
|
static ssize_t tpm_write(struct file *file, const char __user *buf,
|
|
size_t size, loff_t *off)
|
|
{
|
|
struct file_priv *priv = file->private_data;
|
|
size_t in_size = size;
|
|
ssize_t out_size;
|
|
|
|
/* cannot perform a write until the read has cleared
|
|
either via tpm_read or a user_read_timer timeout.
|
|
This also prevents splitted buffered writes from blocking here.
|
|
*/
|
|
if (atomic_read(&priv->data_pending) != 0)
|
|
return -EBUSY;
|
|
|
|
if (in_size > TPM_BUFSIZE)
|
|
return -E2BIG;
|
|
|
|
mutex_lock(&priv->buffer_mutex);
|
|
|
|
if (copy_from_user
|
|
(priv->data_buffer, (void __user *) buf, in_size)) {
|
|
mutex_unlock(&priv->buffer_mutex);
|
|
return -EFAULT;
|
|
}
|
|
|
|
/* atomic tpm command send and result receive. We only hold the ops
|
|
* lock during this period so that the tpm can be unregistered even if
|
|
* the char dev is held open.
|
|
*/
|
|
if (tpm_try_get_ops(priv->chip)) {
|
|
mutex_unlock(&priv->buffer_mutex);
|
|
return -EPIPE;
|
|
}
|
|
out_size = tpm_transmit(priv->chip, priv->data_buffer,
|
|
sizeof(priv->data_buffer), 0);
|
|
|
|
tpm_put_ops(priv->chip);
|
|
if (out_size < 0) {
|
|
mutex_unlock(&priv->buffer_mutex);
|
|
return out_size;
|
|
}
|
|
|
|
atomic_set(&priv->data_pending, out_size);
|
|
mutex_unlock(&priv->buffer_mutex);
|
|
|
|
/* Set a timeout by which the reader must come claim the result */
|
|
mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
|
|
|
|
return in_size;
|
|
}
|
|
|
|
/*
|
|
* Called on file close
|
|
*/
|
|
static int tpm_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct file_priv *priv = file->private_data;
|
|
|
|
del_singleshot_timer_sync(&priv->user_read_timer);
|
|
flush_work(&priv->work);
|
|
file->private_data = NULL;
|
|
atomic_set(&priv->data_pending, 0);
|
|
clear_bit(0, &priv->chip->is_open);
|
|
kfree(priv);
|
|
return 0;
|
|
}
|
|
|
|
const struct file_operations tpm_fops = {
|
|
.owner = THIS_MODULE,
|
|
.llseek = no_llseek,
|
|
.open = tpm_open,
|
|
.read = tpm_read,
|
|
.write = tpm_write,
|
|
.release = tpm_release,
|
|
};
|
|
|
|
|