[PATCH] uacce: use filep->f_mapping to replace inode->i_mapping

[PATCH] uacce: use filep->f_mapping to replace inode->i_mapping

[Zhangfei Gao]

The inode can be different in a container, for example, a docker and host
both open the same uacce parent device, which uses the same uacce struct
but different inode, so uacce->inode is not enough.

What's worse, when docker stops, the inode will be destroyed as well,
causing use-after-free in uacce_remove.

So use q->filep->f_mapping to replace uacce->inode->i_mapping.

Signed-off-by: Weili Qian <qianweili@huawei.com>
Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
---
 drivers/misc/uacce/uacce.c | 16 +++++++++-------
 include/linux/uacce.h      |  4 ++--
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
index 346bd7cf2e94..740ace422baa 100644
--- a/drivers/misc/uacce/uacce.c
+++ b/drivers/misc/uacce/uacce.c
@@ -166,8 +166,8 @@ static int uacce_fops_open(struct inode *inode, struct file *filep)
 
 	init_waitqueue_head(&q->wait);
 	filep->private_data = q;
-	uacce->inode = inode;
 	q->state = UACCE_Q_INIT;
+	q->private_data = filep;
 	mutex_init(&q->mutex);
 	list_add(&q->list, &uacce->queues);
 	mutex_unlock(&uacce->mutex);
@@ -574,12 +574,6 @@ void uacce_remove(struct uacce_device *uacce)
 
 	if (!uacce)
 		return;
-	/*
-	 * unmap remaining mapping from user space, preventing user still
-	 * access the mmaped area while parent device is already removed
-	 */
-	if (uacce->inode)
-		unmap_mapping_range(uacce->inode->i_mapping, 0, 0, 1);
 
 	/*
 	 * uacce_fops_open() may be running concurrently, even after we remove
@@ -589,6 +583,8 @@ void uacce_remove(struct uacce_device *uacce)
 	mutex_lock(&uacce->mutex);
 	/* ensure no open queue remains */
 	list_for_each_entry_safe(q, next_q, &uacce->queues, list) {
+		struct file *filep = q->private_data;
+
 		/*
 		 * Taking q->mutex ensures that fops do not use the defunct
 		 * uacce->ops after the queue is disabled.
@@ -597,6 +593,12 @@ void uacce_remove(struct uacce_device *uacce)
 		uacce_put_queue(q);
 		mutex_unlock(&q->mutex);
 		uacce_unbind_queue(q);
+
+		/*
+		 * unmap remaining mapping from user space, preventing user still
+		 * access the mmaped area while parent device is already removed
+		 */
+		unmap_mapping_range(filep->f_mapping, 0, 0, 1);
 	}
 
 	/* disable sva now since no opened queues */
diff --git a/include/linux/uacce.h b/include/linux/uacce.h
index 0a81c3dfd26c..64b800b74436 100644
--- a/include/linux/uacce.h
+++ b/include/linux/uacce.h
@@ -86,6 +86,7 @@ enum uacce_q_state {
  * @state: queue state machine
  * @pasid: pasid associated to the mm
  * @handle: iommu_sva handle returned by iommu_sva_bind_device()
+ * @private_data: private data for saving filep
  */
 struct uacce_queue {
 	struct uacce_device *uacce;
@@ -97,6 +98,7 @@ struct uacce_queue {
 	enum uacce_q_state state;
 	u32 pasid;
 	struct iommu_sva *handle;
+	void *private_data;
 };
 
 /**
@@ -114,7 +116,6 @@ struct uacce_queue {
  * @mutex: protects uacce operation
  * @priv: private pointer of the uacce
  * @queues: list of queues
- * @inode: core vfs
  */
 struct uacce_device {
 	const char *algs;
@@ -130,7 +131,6 @@ struct uacce_device {
 	struct mutex mutex;
 	void *priv;
 	struct list_head queues;
-	struct inode *inode;
 };
 
 #if IS_ENABLED(CONFIG_UACCE)
-- 
2.39.2 (Apple Git-143)

Re: [PATCH] uacce: use filep->f_mapping to replace inode->i_mapping

[Greg Kroah-Hartman]

On Thu, May 11, 2023 at 10:15:53AM +0800, Zhangfei Gao wrote:
> The inode can be different in a container, for example, a docker and host
> both open the same uacce parent device, which uses the same uacce struct
> but different inode, so uacce->inode is not enough.
> 
> What's worse, when docker stops, the inode will be destroyed as well,
> causing use-after-free in uacce_remove.
> 
> So use q->filep->f_mapping to replace uacce->inode->i_mapping.
> 
> Signed-off-by: Weili Qian <qianweili@huawei.com>
> Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
> ---
>  drivers/misc/uacce/uacce.c | 16 +++++++++-------
>  include/linux/uacce.h      |  4 ++--
>  2 files changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
> index 346bd7cf2e94..740ace422baa 100644
> --- a/drivers/misc/uacce/uacce.c
> +++ b/drivers/misc/uacce/uacce.c
> @@ -166,8 +166,8 @@ static int uacce_fops_open(struct inode *inode, struct file *filep)
>  
>  	init_waitqueue_head(&q->wait);
>  	filep->private_data = q;
> -	uacce->inode = inode;
>  	q->state = UACCE_Q_INIT;
> +	q->private_data = filep;
>  	mutex_init(&q->mutex);
>  	list_add(&q->list, &uacce->queues);
>  	mutex_unlock(&uacce->mutex);
> @@ -574,12 +574,6 @@ void uacce_remove(struct uacce_device *uacce)
>  
>  	if (!uacce)
>  		return;
> -	/*
> -	 * unmap remaining mapping from user space, preventing user still
> -	 * access the mmaped area while parent device is already removed
> -	 */
> -	if (uacce->inode)
> -		unmap_mapping_range(uacce->inode->i_mapping, 0, 0, 1);
>  
>  	/*
>  	 * uacce_fops_open() may be running concurrently, even after we remove
> @@ -589,6 +583,8 @@ void uacce_remove(struct uacce_device *uacce)
>  	mutex_lock(&uacce->mutex);
>  	/* ensure no open queue remains */
>  	list_for_each_entry_safe(q, next_q, &uacce->queues, list) {
> +		struct file *filep = q->private_data;
> +
>  		/*
>  		 * Taking q->mutex ensures that fops do not use the defunct
>  		 * uacce->ops after the queue is disabled.
> @@ -597,6 +593,12 @@ void uacce_remove(struct uacce_device *uacce)
>  		uacce_put_queue(q);
>  		mutex_unlock(&q->mutex);
>  		uacce_unbind_queue(q);
> +
> +		/*
> +		 * unmap remaining mapping from user space, preventing user still
> +		 * access the mmaped area while parent device is already removed
> +		 */
> +		unmap_mapping_range(filep->f_mapping, 0, 0, 1);
>  	}
>  
>  	/* disable sva now since no opened queues */
> diff --git a/include/linux/uacce.h b/include/linux/uacce.h
> index 0a81c3dfd26c..64b800b74436 100644
> --- a/include/linux/uacce.h
> +++ b/include/linux/uacce.h
> @@ -86,6 +86,7 @@ enum uacce_q_state {
>   * @state: queue state machine
>   * @pasid: pasid associated to the mm
>   * @handle: iommu_sva handle returned by iommu_sva_bind_device()
> + * @private_data: private data for saving filep
>   */
>  struct uacce_queue {
>  	struct uacce_device *uacce;
> @@ -97,6 +98,7 @@ struct uacce_queue {
>  	enum uacce_q_state state;
>  	u32 pasid;
>  	struct iommu_sva *handle;
> +	void *private_data;

Make this a real pointer to the inode, no need to make this "void *",
right?

thanks,

greg k-h

Re: [PATCH] uacce: use filep->f_mapping to replace inode->i_mapping

[Al Viro]

On Thu, May 11, 2023 at 10:15:53AM +0800, Zhangfei Gao wrote:
> The inode can be different in a container, for example, a docker and host
> both open the same uacce parent device, which uses the same uacce struct
> but different inode, so uacce->inode is not enough.
> 
> What's worse, when docker stops, the inode will be destroyed as well,
> causing use-after-free in uacce_remove.
> 
> So use q->filep->f_mapping to replace uacce->inode->i_mapping.

> @@ -574,12 +574,6 @@ void uacce_remove(struct uacce_device *uacce)
>  
>  	if (!uacce)
>  		return;
> -	/*
> -	 * unmap remaining mapping from user space, preventing user still
> -	 * access the mmaped area while parent device is already removed
> -	 */
> -	if (uacce->inode)
> -		unmap_mapping_range(uacce->inode->i_mapping, 0, 0, 1);
>  
>  	/*
>  	 * uacce_fops_open() may be running concurrently, even after we remove
> @@ -589,6 +583,8 @@ void uacce_remove(struct uacce_device *uacce)
>  	mutex_lock(&uacce->mutex);
>  	/* ensure no open queue remains */
>  	list_for_each_entry_safe(q, next_q, &uacce->queues, list) {
> +		struct file *filep = q->private_data;
> +
>  		/*
>  		 * Taking q->mutex ensures that fops do not use the defunct
>  		 * uacce->ops after the queue is disabled.
> @@ -597,6 +593,12 @@ void uacce_remove(struct uacce_device *uacce)
>  		uacce_put_queue(q);
>  		mutex_unlock(&q->mutex);
>  		uacce_unbind_queue(q);
> +
> +		/*
> +		 * unmap remaining mapping from user space, preventing user still
> +		 * access the mmaped area while parent device is already removed
> +		 */
> +		unmap_mapping_range(filep->f_mapping, 0, 0, 1);

IDGI.  Going through uacce_queue instead of uacce_device is fine, but why
bother with file *or* inode?  Just store a reference to struct address_space in
your uacce_queue and be done with that...

Another problem in that driver is uacce_vma_close(); this
        if (vma->vm_pgoff < UACCE_MAX_REGION)
                qfr = q->qfrs[vma->vm_pgoff];

        kfree(qfr);
can't be right - you have q->qfrs left pointing to freed object.  If nothing
else, subsequent mmap() will fail with -EEXIST, won't it?

Re: [PATCH] uacce: use filep->f_mapping to replace inode->i_mapping

[Zhangfei Gao]

On Thu, 11 May 2023 at 12:05, Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> On Thu, May 11, 2023 at 10:15:53AM +0800, Zhangfei Gao wrote:
> > The inode can be different in a container, for example, a docker and host
> > both open the same uacce parent device, which uses the same uacce struct
> > but different inode, so uacce->inode is not enough.
> >
> > What's worse, when docker stops, the inode will be destroyed as well,
> > causing use-after-free in uacce_remove.
> >
> > So use q->filep->f_mapping to replace uacce->inode->i_mapping.
>
> > @@ -574,12 +574,6 @@ void uacce_remove(struct uacce_device *uacce)
> >
> >       if (!uacce)
> >               return;
> > -     /*
> > -      * unmap remaining mapping from user space, preventing user still
> > -      * access the mmaped area while parent device is already removed
> > -      */
> > -     if (uacce->inode)
> > -             unmap_mapping_range(uacce->inode->i_mapping, 0, 0, 1);
> >
> >       /*
> >        * uacce_fops_open() may be running concurrently, even after we remove
> > @@ -589,6 +583,8 @@ void uacce_remove(struct uacce_device *uacce)
> >       mutex_lock(&uacce->mutex);
> >       /* ensure no open queue remains */
> >       list_for_each_entry_safe(q, next_q, &uacce->queues, list) {
> > +             struct file *filep = q->private_data;
> > +
> >               /*
> >                * Taking q->mutex ensures that fops do not use the defunct
> >                * uacce->ops after the queue is disabled.
> > @@ -597,6 +593,12 @@ void uacce_remove(struct uacce_device *uacce)
> >               uacce_put_queue(q);
> >               mutex_unlock(&q->mutex);
> >               uacce_unbind_queue(q);
> > +
> > +             /*
> > +              * unmap remaining mapping from user space, preventing user still
> > +              * access the mmaped area while parent device is already removed
> > +              */
> > +             unmap_mapping_range(filep->f_mapping, 0, 0, 1);
>
> IDGI.  Going through uacce_queue instead of uacce_device is fine, but why
> bother with file *or* inode?  Just store a reference to struct address_space in
> your uacce_queue and be done with that...

Yes, a struct address_space is enough.

>
> Another problem in that driver is uacce_vma_close(); this
>         if (vma->vm_pgoff < UACCE_MAX_REGION)
>                 qfr = q->qfrs[vma->vm_pgoff];
>
>         kfree(qfr);
> can't be right - you have q->qfrs left pointing to freed object.  If nothing
> else, subsequent mmap() will fail with -EEXIST, won't it?

Good catch, will fix it.

Thanks

[PATCH v2 0/2] uacce misc fix

[Zhangfei Gao]

v2:
using q->mapping instead of inode or file
vma_close clears q->qfrs as well

Zhangfei Gao (2):
  uacce: use q->mapping to replace inode->i_mapping
  uacce: vma_close clears q->qfrs when freeing qfrs

 drivers/misc/uacce/uacce.c | 25 ++++++++++++++-----------
 include/linux/uacce.h      |  4 ++--
 2 files changed, 16 insertions(+), 13 deletions(-)

-- 
2.39.2 (Apple Git-143)

[PATCH v2 1/2] uacce: use q->mapping to replace inode->i_mapping

[Zhangfei Gao]

The inode can be different in a container, for example, a docker and host
both open the same uacce parent device, which uses the same uacce struct
but different inode, so uacce->inode is not enough.

What's worse, when docker stops, the inode will be destroyed as well,
causing use-after-free in uacce_remove.

So use q->mapping to replace uacce->inode->i_mapping.

Signed-off-by: Weili Qian <qianweili@huawei.com>
Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
---
 drivers/misc/uacce/uacce.c | 14 +++++++-------
 include/linux/uacce.h      |  4 ++--
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
index 346bd7cf2e94..338b59ef5493 100644
--- a/drivers/misc/uacce/uacce.c
+++ b/drivers/misc/uacce/uacce.c
@@ -166,8 +166,8 @@ static int uacce_fops_open(struct inode *inode, struct file *filep)
 
 	init_waitqueue_head(&q->wait);
 	filep->private_data = q;
-	uacce->inode = inode;
 	q->state = UACCE_Q_INIT;
+	q->mapping = filep->f_mapping;
 	mutex_init(&q->mutex);
 	list_add(&q->list, &uacce->queues);
 	mutex_unlock(&uacce->mutex);
@@ -574,12 +574,6 @@ void uacce_remove(struct uacce_device *uacce)
 
 	if (!uacce)
 		return;
-	/*
-	 * unmap remaining mapping from user space, preventing user still
-	 * access the mmaped area while parent device is already removed
-	 */
-	if (uacce->inode)
-		unmap_mapping_range(uacce->inode->i_mapping, 0, 0, 1);
 
 	/*
 	 * uacce_fops_open() may be running concurrently, even after we remove
@@ -597,6 +591,12 @@ void uacce_remove(struct uacce_device *uacce)
 		uacce_put_queue(q);
 		mutex_unlock(&q->mutex);
 		uacce_unbind_queue(q);
+
+		/*
+		 * unmap remaining mapping from user space, preventing user still
+		 * access the mmaped area while parent device is already removed
+		 */
+		unmap_mapping_range(q->mapping, 0, 0, 1);
 	}
 
 	/* disable sva now since no opened queues */
diff --git a/include/linux/uacce.h b/include/linux/uacce.h
index 0a81c3dfd26c..e290c0269944 100644
--- a/include/linux/uacce.h
+++ b/include/linux/uacce.h
@@ -86,6 +86,7 @@ enum uacce_q_state {
  * @state: queue state machine
  * @pasid: pasid associated to the mm
  * @handle: iommu_sva handle returned by iommu_sva_bind_device()
+ * @mapping: user space mapping of the queue
  */
 struct uacce_queue {
 	struct uacce_device *uacce;
@@ -97,6 +98,7 @@ struct uacce_queue {
 	enum uacce_q_state state;
 	u32 pasid;
 	struct iommu_sva *handle;
+	struct address_space *mapping;
 };
 
 /**
@@ -114,7 +116,6 @@ struct uacce_queue {
  * @mutex: protects uacce operation
  * @priv: private pointer of the uacce
  * @queues: list of queues
- * @inode: core vfs
  */
 struct uacce_device {
 	const char *algs;
@@ -130,7 +131,6 @@ struct uacce_device {
 	struct mutex mutex;
 	void *priv;
 	struct list_head queues;
-	struct inode *inode;
 };
 
 #if IS_ENABLED(CONFIG_UACCE)
-- 
2.39.2 (Apple Git-143)

[PATCH v2 2/2] uacce: vma_close clears q->qfrs when freeing qfrs

[Zhangfei Gao]

vma_close frees qfrs but not clears q->qfrs, which still points
to the freed object, leading to subsequent mmap fail.
So vma_close clears q->qfrs as well.

Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
---
 drivers/misc/uacce/uacce.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
index 338b59ef5493..930c252753a0 100644
--- a/drivers/misc/uacce/uacce.c
+++ b/drivers/misc/uacce/uacce.c
@@ -200,12 +200,15 @@ static int uacce_fops_release(struct inode *inode, struct file *filep)
 static void uacce_vma_close(struct vm_area_struct *vma)
 {
 	struct uacce_queue *q = vma->vm_private_data;
-	struct uacce_qfile_region *qfr = NULL;
 
-	if (vma->vm_pgoff < UACCE_MAX_REGION)
-		qfr = q->qfrs[vma->vm_pgoff];
+	if (vma->vm_pgoff < UACCE_MAX_REGION) {
+		struct uacce_qfile_region *qfr = q->qfrs[vma->vm_pgoff];
 
-	kfree(qfr);
+		mutex_lock(&q->mutex);
+		q->qfrs[vma->vm_pgoff] = NULL;
+		mutex_unlock(&q->mutex);
+		kfree(qfr);
+	}
 }
 
 static const struct vm_operations_struct uacce_vm_ops = {
-- 
2.39.2 (Apple Git-143)