Re: [PATCH v3 08/13] vdpa: add return value to get_config/set_config callbacks

[Michael S. Tsirkin]

On Fri, Feb 05, 2021 at 09:48:47AM +0100, Stefano Garzarella wrote:
> Adding Eli in the loop.
> 
> On Fri, Feb 05, 2021 at 11:20:11AM +0800, Jason Wang wrote:
> > 
> > On 2021/2/5 上午1:22, Stefano Garzarella wrote:
> > > All implementations of these callbacks already validate inputs.
> > > 
> > > Let's return an error from these callbacks, so the caller doesn't
> > > need to validate the input anymore.
> > > 
> > > We update all implementations to return -EINVAL in case of invalid
> > > input.
> > > 
> > > Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
> > > ---
> > >  include/linux/vdpa.h              | 18 ++++++++++--------
> > >  drivers/vdpa/ifcvf/ifcvf_main.c   | 24 ++++++++++++++++--------
> > >  drivers/vdpa/mlx5/net/mlx5_vnet.c | 17 +++++++++++------
> > >  drivers/vdpa/vdpa_sim/vdpa_sim.c  | 16 ++++++++++------
> > >  4 files changed, 47 insertions(+), 28 deletions(-)
> > > 
> > > diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> > > index 4ab5494503a8..0e0cbd5fb41b 100644
> > > --- a/include/linux/vdpa.h
> > > +++ b/include/linux/vdpa.h
> > > @@ -157,6 +157,7 @@ struct vdpa_iova_range {
> > >   *				@buf: buffer used to read to
> > >   *				@len: the length to read from
> > >   *				configuration space
> > > + *				Returns integer: success (0) or error (< 0)
> > >   * @set_config:			Write to device specific configuration space
> > >   *				@vdev: vdpa device
> > >   *				@offset: offset from the beginning of
> > > @@ -164,6 +165,7 @@ struct vdpa_iova_range {
> > >   *				@buf: buffer used to write from
> > >   *				@len: the length to write to
> > >   *				configuration space
> > > + *				Returns integer: success (0) or error (< 0)
> > >   * @get_generation:		Get device config generation (optional)
> > >   *				@vdev: vdpa device
> > >   *				Returns u32: device generation
> > > @@ -231,10 +233,10 @@ struct vdpa_config_ops {
> > >  	u32 (*get_vendor_id)(struct vdpa_device *vdev);
> > >  	u8 (*get_status)(struct vdpa_device *vdev);
> > >  	void (*set_status)(struct vdpa_device *vdev, u8 status);
> > > -	void (*get_config)(struct vdpa_device *vdev, unsigned int offset,
> > > -			   void *buf, unsigned int len);
> > > -	void (*set_config)(struct vdpa_device *vdev, unsigned int offset,
> > > -			   const void *buf, unsigned int len);
> > > +	int (*get_config)(struct vdpa_device *vdev, unsigned int offset,
> > > +			  void *buf, unsigned int len);
> > > +	int (*set_config)(struct vdpa_device *vdev, unsigned int offset,
> > > +			  const void *buf, unsigned int len);
> > >  	u32 (*get_generation)(struct vdpa_device *vdev);
> > >  	struct vdpa_iova_range (*get_iova_range)(struct vdpa_device *vdev);
> > > @@ -329,8 +331,8 @@ static inline int vdpa_set_features(struct vdpa_device *vdev, u64 features)
> > >  }
> > > -static inline void vdpa_get_config(struct vdpa_device *vdev, unsigned offset,
> > > -				   void *buf, unsigned int len)
> > > +static inline int vdpa_get_config(struct vdpa_device *vdev, unsigned offset,
> > > +				  void *buf, unsigned int len)
> > >  {
> > >          const struct vdpa_config_ops *ops = vdev->config;
> > > @@ -339,8 +341,8 @@ static inline void vdpa_get_config(struct vdpa_device *vdev, unsigned offset,
> > >  	 * If it does happen we assume a legacy guest.
> > >  	 */
> > >  	if (!vdev->features_valid)
> > > -		vdpa_set_features(vdev, 0);
> > > -	ops->get_config(vdev, offset, buf, len);
> > > +		return vdpa_set_features(vdev, 0);
> > > +	return ops->get_config(vdev, offset, buf, len);
> > >  }
> > >  /**
> > > diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
> > > index 7c8bbfcf6c3e..f5e6a90d8114 100644
> > > --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> > > +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> > > @@ -332,24 +332,32 @@ static u32 ifcvf_vdpa_get_vq_align(struct vdpa_device *vdpa_dev)
> > >  	return IFCVF_QUEUE_ALIGNMENT;
> > >  }
> > > -static void ifcvf_vdpa_get_config(struct vdpa_device *vdpa_dev,
> > > -				  unsigned int offset,
> > > -				  void *buf, unsigned int len)
> > > +static int ifcvf_vdpa_get_config(struct vdpa_device *vdpa_dev,
> > > +				 unsigned int offset,
> > > +				 void *buf, unsigned int len)
> > >  {
> > >  	struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
> > > -	WARN_ON(offset + len > sizeof(struct virtio_net_config));
> > > +	if (offset + len > sizeof(struct virtio_net_config))
> > > +		return -EINVAL;
> > > +
> > >  	ifcvf_read_net_config(vf, offset, buf, len);
> > > +
> > > +	return 0;
> > >  }
> > > -static void ifcvf_vdpa_set_config(struct vdpa_device *vdpa_dev,
> > > -				  unsigned int offset, const void *buf,
> > > -				  unsigned int len)
> > > +static int ifcvf_vdpa_set_config(struct vdpa_device *vdpa_dev,
> > > +				 unsigned int offset, const void *buf,
> > > +				 unsigned int len)
> > >  {
> > >  	struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
> > > -	WARN_ON(offset + len > sizeof(struct virtio_net_config));
> > > +	if (offset + len > sizeof(struct virtio_net_config))
> > > +		return -EINVAL;
> > > +
> > >  	ifcvf_write_net_config(vf, offset, buf, len);
> > > +
> > > +	return 0;
> > >  }
> > >  static void ifcvf_vdpa_set_config_cb(struct vdpa_device *vdpa_dev,
> > > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > > index 029822060017..9323b5ff7988 100644
> > > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > > @@ -1796,20 +1796,25 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
> > >  	ndev->mvdev.status |= VIRTIO_CONFIG_S_FAILED;
> > >  }
> > > -static void mlx5_vdpa_get_config(struct vdpa_device *vdev, unsigned int offset, void *buf,
> > > -				 unsigned int len)
> > > +static int mlx5_vdpa_get_config(struct vdpa_device *vdev, unsigned int offset, void *buf,
> > > +				unsigned int len)
> > >  {
> > >  	struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev);
> > >  	struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
> > > -	if (offset + len < sizeof(struct virtio_net_config))
> > > -		memcpy(buf, (u8 *)&ndev->config + offset, len);
> > > +	if (offset + len > sizeof(struct virtio_net_config))
> > > +		return -EINVAL;
> > 
> > 
> > It looks to me we should use ">=" here?
> 
> 
> Ehmm, I think it was wrong before this patch. If 'offset + len' is equal to
> 'sizeof(struct virtio_net_config)', should be okay to copy, no?
> 
> I think it's one of the rare cases where the copy and paste went well :-)
> 
> Should I fix this in a separate patch?
> 
> Thanks,
> Stefano

Sure.