tpm: add support for nonblocking operation

Message ID	152780934926.32219.7291994735609525171.stgit@tstruk-mobl1.jf.intel.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-integrity-owner@kernel.org> Subject: [PATCH] tpm: add support for nonblocking operation From: Tadeusz Struk <tadeusz.struk@intel.com> To: jarkko.sakkinen@linux.intel.com Cc: jgg@ziepe.ca, linux-integrity@vger.kernel.org, tadeusz.struk@intel.com Date: Thu, 31 May 2018 16:29:09 -0700 Message-ID: <152780934926.32219.7291994735609525171.stgit@tstruk-mobl1.jf.intel.com> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk

diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c index e4a04b2d3c32..0f3378b5198a 100644 --- a/drivers/char/tpm/tpm-dev-common.c +++ b/drivers/char/tpm/tpm-dev-common.c @@ -17,11 +17,46 @@ * License. * */ +#include <linux/poll.h> +#include <linux/sched/signal.h> #include <linux/slab.h> #include <linux/uaccess.h> +#include <linux/workqueue.h> #include "tpm.h" #include "tpm-dev.h" +static DECLARE_WAIT_QUEUE_HEAD(tpm_dev_wait); +static struct workqueue_struct *tpm_dev_wq; + +struct tpm_dev_work { + struct work_struct work; + struct file_priv *priv; + struct tpm_space *space; + ssize_t resp_size; + bool nonblocking; +}; + +static void tpm_async_work(struct work_struct *work) +{ + struct tpm_dev_work *tpm_work = + container_of(work, struct tpm_dev_work, work); + struct file_priv *priv = tpm_work->priv; + + tpm_work->resp_size = tpm_transmit(priv->chip, tpm_work->space, + priv->data_buffer, + sizeof(priv->data_buffer), 0); + if (!tpm_work->nonblocking) { + wake_up_interruptible(&tpm_dev_wait); + return; + } + + tpm_put_ops(priv->chip); + priv->data_pending = tpm_work->resp_size; + mutex_unlock(&priv->buffer_mutex); + mod_timer(&priv->user_read_timer, jiffies + (120 * HZ)); + kfree(tpm_work); +} + static void user_reader_timeout(struct timer_list *t) { struct file_priv *priv = from_timer(priv, t, user_read_timer); @@ -40,6 +75,7 @@ static void timeout_work(struct work_struct *work) priv->data_pending = 0; memset(priv->data_buffer, 0, sizeof(priv->data_buffer)); mutex_unlock(&priv->buffer_mutex); + wake_up_interruptible(&tpm_dev_wait); } void tpm_common_open(struct file *file, struct tpm_chip *chip, @@ -66,10 +102,12 @@ ssize_t tpm_common_read(struct file *file, char __user *buf, if (priv->data_pending) { ret_size = min_t(ssize_t, size, priv->data_pending); - rc = copy_to_user(buf, priv->data_buffer, ret_size); - memset(priv->data_buffer, 0, priv->data_pending); - if (rc) - ret_size = -EFAULT; + if (ret_size > 0) { + rc = copy_to_user(buf, priv->data_buffer, ret_size); + memset(priv->data_buffer, 0, priv->data_pending); + if (rc) + ret_size = -EFAULT; + } priv->data_pending = 0; } @@ -82,10 +120,11 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf, size_t size, loff_t *off, struct tpm_space *space) { struct file_priv *priv = file->private_data; - size_t in_size = size; - ssize_t out_size; + struct tpm_dev_work *work; + DECLARE_WAITQUEUE(wait, current); + int ret = 0; - if (in_size > TPM_BUFSIZE) + if (size > TPM_BUFSIZE) return -E2BIG; mutex_lock(&priv->buffer_mutex); @@ -95,20 +134,19 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf, * buffered writes from blocking here. */ if (priv->data_pending != 0) { - mutex_unlock(&priv->buffer_mutex); - return -EBUSY; + ret = -EBUSY; + goto out; } - if (copy_from_user - (priv->data_buffer, (void __user *) buf, in_size)) { - mutex_unlock(&priv->buffer_mutex); - return -EFAULT; + if (copy_from_user(priv->data_buffer, buf, size)) { + ret = -EFAULT; + goto out; } - if (in_size < 6 || - in_size < be32_to_cpu(*((__be32 *) (priv->data_buffer + 2)))) { - mutex_unlock(&priv->buffer_mutex); - return -EINVAL; + if (size < 6 || + size < be32_to_cpu(*((__be32 *)(priv->data_buffer + 2)))) { + ret = -EINVAL; + goto out; } /* atomic tpm command send and result receive. We only hold the ops @@ -116,25 +154,85 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf, * the char dev is held open. */ if (tpm_try_get_ops(priv->chip)) { - mutex_unlock(&priv->buffer_mutex); - return -EPIPE; + ret = -EPIPE; + goto out; } - out_size = tpm_transmit(priv->chip, space, priv->data_buffer, - sizeof(priv->data_buffer), 0); + /* + * Schedule an async job to send the command + */ + work = kzalloc(sizeof(*work), GFP_KERNEL); + if (!work) { + tpm_put_ops(priv->chip); + ret = -ENOMEM; + goto out; + } + + work->priv = priv; + work->space = space; + work->nonblocking = file->f_flags & O_NONBLOCK; + INIT_WORK(&work->work, tpm_async_work); + queue_work(tpm_dev_wq, &work->work); + + /* + * If in nonblocking mode, return the size. + * In case of an error the error code will be + * returned in the subsequent read call. + */ + if (work->nonblocking) + return size; + + add_wait_queue(&tpm_dev_wait, &wait); + current->state = TASK_INTERRUPTIBLE; + for (;;) { + if (work->resp_size) + break; + + if (signal_pending(current)) { + ret = -ERESTARTSYS; + break; + } + schedule(); + } + current->state = TASK_RUNNING; + remove_wait_queue(&tpm_dev_wait, &wait); tpm_put_ops(priv->chip); - if (out_size < 0) { - mutex_unlock(&priv->buffer_mutex); - return out_size; + + if (ret) + goto out_free; + + if (work->resp_size < 0) { + ret = work->resp_size; + goto out_free; } - priv->data_pending = out_size; + priv->data_pending = work->resp_size; + kfree(work); mutex_unlock(&priv->buffer_mutex); - - /* Set a timeout by which the reader must come claim the result */ + wake_up_interruptible(&tpm_dev_wait); mod_timer(&priv->user_read_timer, jiffies + (120 * HZ)); + return size; + +out_free: + kfree(work); +out: + mutex_unlock(&priv->buffer_mutex); + return ret; +} + +__poll_t tpm_common_poll(struct file *file, poll_table *wait) +{ + struct file_priv *priv = file->private_data; + __poll_t mask = 0; + + poll_wait(file, &tpm_dev_wait, wait); + + if (priv->data_pending) + mask = EPOLLIN | EPOLLRDNORM; + else + mask = EPOLLOUT | EPOLLWRNORM; - return in_size; + return mask; } /* @@ -147,3 +245,19 @@ void tpm_common_release(struct file *file, struct file_priv *priv) file->private_data = NULL; priv->data_pending = 0; } + +static int __init tpm_dev_common_init(void) +{ + tpm_dev_wq = alloc_workqueue("tpm_dev_wq", WQ_MEM_RECLAIM, 0); + + return !tpm_dev_wq ? -ENOMEM : 0; +} + +late_initcall(tpm_dev_common_init); + +static void __exit tpm_dev_common_exit(void) +{ + destroy_workqueue(tpm_dev_wq); +} + +__exitcall(tpm_dev_common_exit); diff --git a/drivers/char/tpm/tpm-dev.c b/drivers/char/tpm/tpm-dev.c index ebd74ab5abef..dc0fdfdf24c4 100644 --- a/drivers/char/tpm/tpm-dev.c +++ b/drivers/char/tpm/tpm-dev.c @@ -74,5 +74,6 @@ const struct file_operations tpm_fops = { .open = tpm_open, .read = tpm_common_read, .write = tpm_write, + .poll = tpm_common_poll, .release = tpm_release, }; diff --git a/drivers/char/tpm/tpm-dev.h b/drivers/char/tpm/tpm-dev.h index b24cfb4d3ee1..61a3ee0024e4 100644 --- a/drivers/char/tpm/tpm-dev.h +++ b/drivers/char/tpm/tpm-dev.h @@ -2,13 +2,13 @@ #ifndef _TPM_DEV_H #define _TPM_DEV_H +#include <linux/poll.h> #include "tpm.h" struct file_priv { struct tpm_chip *chip; - - /* Data passed to and from the tpm via the read/write calls */ - size_t data_pending; + /* Holds the amount of data passed or an error code from async op */ + ssize_t data_pending; struct mutex buffer_mutex; struct timer_list user_read_timer; /* user needs to claim result */ @@ -23,6 +23,7 @@ ssize_t tpm_common_read(struct file *file, char __user *buf, size_t size, loff_t *off); ssize_t tpm_common_write(struct file *file, const char __user *buf, size_t size, loff_t *off, struct tpm_space *space); -void tpm_common_release(struct file *file, struct file_priv *priv); +__poll_t tpm_common_poll(struct file *file, poll_table *wait); +void tpm_common_release(struct file *file, struct file_priv *priv); #endif diff --git a/drivers/char/tpm/tpmrm-dev.c b/drivers/char/tpm/tpmrm-dev.c index 1a0e97a5da5a..bbfd384b67b2 100644 --- a/drivers/char/tpm/tpmrm-dev.c +++ b/drivers/char/tpm/tpmrm-dev.c @@ -60,6 +60,7 @@ const struct file_operations tpmrm_fops = { .open = tpmrm_open, .read = tpm_common_read, .write = tpmrm_write, + .poll = tpm_common_poll, .release = tpmrm_release, };

tpm: add support for nonblocking operation

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