[PATCH v4 0/2] dma-mapping: Add vmap checks to dma_map_single()

[PATCH v4 0/2] dma-mapping: Add vmap checks to dma_map_single()

[Kees Cook]

v4: use dev_WARN_ONCE() and improve report string (gregkh, robin)
v3: https://lore.kernel.org/lkml/20191010222829.21940-1-keescook@chromium.org
v2: https://lore.kernel.org/lkml/201910041420.F6E55D29A@keescook
v1: https://lore.kernel.org/lkml/201910021341.7819A660@keescook

Duplicating patch 1 commit log:

As we've seen from USB and other areas[1], we need to always do runtime
checks for DMA operating on memory regions that might be remapped. This
adds vmap checks (similar to those already in USB but missing in other
places) into dma_map_single() so all callers benefit from the checking.

[1] https://git.kernel.org/linus/3840c5b78803b2b6cc1ff820100a74a092c40cbb

-Kees

Kees Cook (2):
  dma-mapping: Add vmap checks to dma_map_single()
  usb: core: Remove redundant vmap checks

 drivers/usb/core/hcd.c      | 8 +-------
 include/linux/dma-mapping.h | 6 ++++++
 2 files changed, 7 insertions(+), 7 deletions(-)

-- 
2.17.1

[PATCH v4 1/2] dma-mapping: Add vmap checks to dma_map_single()

[Kees Cook]

As we've seen from USB and other areas[1], we need to always do runtime
checks for DMA operating on memory regions that might be remapped. This
adds vmap checks (similar to those already in USB but missing in other
places) into dma_map_single() so all callers benefit from the checking.

[1] https://git.kernel.org/linus/3840c5b78803b2b6cc1ff820100a74a092c40cbb

Suggested-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 include/linux/dma-mapping.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 4a1c4fca475a..54de3c496407 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -583,6 +583,12 @@ static inline unsigned long dma_get_merge_boundary(struct device *dev)
 static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr,
 		size_t size, enum dma_data_direction dir, unsigned long attrs)
 {
+	/* DMA must never operate on areas that might be remapped. */
+	if (dev_WARN_ONCE(dev, is_vmalloc_addr(ptr),
+			  "wanted %zu bytes mapped in vmalloc\n", size)) {
+		return DMA_MAPPING_ERROR;
+	}
+
 	debug_dma_map_single(dev, ptr, size);
 	return dma_map_page_attrs(dev, virt_to_page(ptr), offset_in_page(ptr),
 			size, dir, attrs);
-- 
2.17.1

[PATCH v4 2/2] usb: core: Remove redundant vmap checks

[Kees Cook]

Now that the vmap area checks are being performed in the DMA
infrastructure directly, there is no need to repeat them in USB.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/usb/core/hcd.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index f225eaa98ff8..281568d464f9 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1410,10 +1410,7 @@ int usb_hcd_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
 		if (hcd->self.uses_pio_for_control)
 			return ret;
 		if (hcd_uses_dma(hcd)) {
-			if (is_vmalloc_addr(urb->setup_packet)) {
-				WARN_ONCE(1, "setup packet is not dma capable\n");
-				return -EAGAIN;
-			} else if (object_is_on_stack(urb->setup_packet)) {
+			if (object_is_on_stack(urb->setup_packet)) {
 				WARN_ONCE(1, "setup packet is on stack\n");
 				return -EAGAIN;
 			}
@@ -1479,9 +1476,6 @@ int usb_hcd_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
 					ret = -EAGAIN;
 				else
 					urb->transfer_flags |= URB_DMA_MAP_PAGE;
-			} else if (is_vmalloc_addr(urb->transfer_buffer)) {
-				WARN_ONCE(1, "transfer buffer not dma capable\n");
-				ret = -EAGAIN;
 			} else if (object_is_on_stack(urb->transfer_buffer)) {
 				WARN_ONCE(1, "transfer buffer is on stack\n");
 				ret = -EAGAIN;
-- 
2.17.1

Re: [PATCH v4 1/2] dma-mapping: Add vmap checks to dma_map_single()

[Greg Kroah-Hartman]

On Tue, Oct 29, 2019 at 02:34:22PM -0700, Kees Cook wrote:
> As we've seen from USB and other areas[1], we need to always do runtime
> checks for DMA operating on memory regions that might be remapped. This
> adds vmap checks (similar to those already in USB but missing in other
> places) into dma_map_single() so all callers benefit from the checking.
> 
> [1] https://git.kernel.org/linus/3840c5b78803b2b6cc1ff820100a74a092c40cbb
> 
> Suggested-by: Laura Abbott <labbott@redhat.com>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  include/linux/dma-mapping.h | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index 4a1c4fca475a..54de3c496407 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -583,6 +583,12 @@ static inline unsigned long dma_get_merge_boundary(struct device *dev)
>  static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr,
>  		size_t size, enum dma_data_direction dir, unsigned long attrs)
>  {
> +	/* DMA must never operate on areas that might be remapped. */
> +	if (dev_WARN_ONCE(dev, is_vmalloc_addr(ptr),
> +			  "wanted %zu bytes mapped in vmalloc\n", size)) {
> +		return DMA_MAPPING_ERROR;
> +	}

That's a very odd error string, I know if I saw it for the first time, I
would have no idea what it meant.  The USB message at least gives you a
bit more context as to what went wrong and how to fix it.

How about something like "Memory is not DMA capabable, please fix the
allocation of it to be correct", or "non-dma-able memory was attempted
to be mapped, but this is impossible to to" or something else.

thanks,

greg k-h

Re: [PATCH v4 1/2] dma-mapping: Add vmap checks to dma_map_single()

[Christoph Hellwig]

On Wed, Oct 30, 2019 at 10:18:49AM +0100, Greg Kroah-Hartman wrote:
> On Tue, Oct 29, 2019 at 02:34:22PM -0700, Kees Cook wrote:
> > As we've seen from USB and other areas[1], we need to always do runtime
> > checks for DMA operating on memory regions that might be remapped. This
> > adds vmap checks (similar to those already in USB but missing in other
> > places) into dma_map_single() so all callers benefit from the checking.
> > 
> > [1] https://git.kernel.org/linus/3840c5b78803b2b6cc1ff820100a74a092c40cbb
> > 
> > Suggested-by: Laura Abbott <labbott@redhat.com>
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> > ---
> >  include/linux/dma-mapping.h | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> > index 4a1c4fca475a..54de3c496407 100644
> > --- a/include/linux/dma-mapping.h
> > +++ b/include/linux/dma-mapping.h
> > @@ -583,6 +583,12 @@ static inline unsigned long dma_get_merge_boundary(struct device *dev)
> >  static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr,
> >  		size_t size, enum dma_data_direction dir, unsigned long attrs)
> >  {
> > +	/* DMA must never operate on areas that might be remapped. */
> > +	if (dev_WARN_ONCE(dev, is_vmalloc_addr(ptr),
> > +			  "wanted %zu bytes mapped in vmalloc\n", size)) {
> > +		return DMA_MAPPING_ERROR;
> > +	}
> 
> That's a very odd error string, I know if I saw it for the first time, I
> would have no idea what it meant.  The USB message at least gives you a
> bit more context as to what went wrong and how to fix it.
> 
> How about something like "Memory is not DMA capabable, please fix the
> allocation of it to be correct", or "non-dma-able memory was attempted
> to be mapped, but this is impossible to to" or something else.

I've fixed the message to "rejecting DMA map of vmalloc memory" and
applied the patch.

Re: [PATCH v4 1/2] dma-mapping: Add vmap checks to dma_map_single()

[Kees Cook]

On Wed, Oct 30, 2019 at 07:09:21PM +0100, Christoph Hellwig wrote:
> On Wed, Oct 30, 2019 at 10:18:49AM +0100, Greg Kroah-Hartman wrote:
> > On Tue, Oct 29, 2019 at 02:34:22PM -0700, Kees Cook wrote:
> > > As we've seen from USB and other areas[1], we need to always do runtime
> > > checks for DMA operating on memory regions that might be remapped. This
> > > adds vmap checks (similar to those already in USB but missing in other
> > > places) into dma_map_single() so all callers benefit from the checking.
> > > 
> > > [1] https://git.kernel.org/linus/3840c5b78803b2b6cc1ff820100a74a092c40cbb
> > > 
> > > Suggested-by: Laura Abbott <labbott@redhat.com>
> > > Signed-off-by: Kees Cook <keescook@chromium.org>
> > > ---
> > >  include/linux/dma-mapping.h | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > > 
> > > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> > > index 4a1c4fca475a..54de3c496407 100644
> > > --- a/include/linux/dma-mapping.h
> > > +++ b/include/linux/dma-mapping.h
> > > @@ -583,6 +583,12 @@ static inline unsigned long dma_get_merge_boundary(struct device *dev)
> > >  static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr,
> > >  		size_t size, enum dma_data_direction dir, unsigned long attrs)
> > >  {
> > > +	/* DMA must never operate on areas that might be remapped. */
> > > +	if (dev_WARN_ONCE(dev, is_vmalloc_addr(ptr),
> > > +			  "wanted %zu bytes mapped in vmalloc\n", size)) {
> > > +		return DMA_MAPPING_ERROR;
> > > +	}
> > 
> > That's a very odd error string, I know if I saw it for the first time, I
> > would have no idea what it meant.  The USB message at least gives you a
> > bit more context as to what went wrong and how to fix it.
> > 
> > How about something like "Memory is not DMA capabable, please fix the
> > allocation of it to be correct", or "non-dma-able memory was attempted
> > to be mapped, but this is impossible to to" or something else.
> 
> I've fixed the message to "rejecting DMA map of vmalloc memory" and
> applied the patch.

Great; thank you!

-- 
Kees Cook

Re: [PATCH v4 1/2] dma-mapping: Add vmap checks to dma_map_single()

[Greg Kroah-Hartman]

On Wed, Oct 30, 2019 at 07:09:21PM +0100, Christoph Hellwig wrote:
> On Wed, Oct 30, 2019 at 10:18:49AM +0100, Greg Kroah-Hartman wrote:
> > On Tue, Oct 29, 2019 at 02:34:22PM -0700, Kees Cook wrote:
> > > As we've seen from USB and other areas[1], we need to always do runtime
> > > checks for DMA operating on memory regions that might be remapped. This
> > > adds vmap checks (similar to those already in USB but missing in other
> > > places) into dma_map_single() so all callers benefit from the checking.
> > > 
> > > [1] https://git.kernel.org/linus/3840c5b78803b2b6cc1ff820100a74a092c40cbb
> > > 
> > > Suggested-by: Laura Abbott <labbott@redhat.com>
> > > Signed-off-by: Kees Cook <keescook@chromium.org>
> > > ---
> > >  include/linux/dma-mapping.h | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > > 
> > > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> > > index 4a1c4fca475a..54de3c496407 100644
> > > --- a/include/linux/dma-mapping.h
> > > +++ b/include/linux/dma-mapping.h
> > > @@ -583,6 +583,12 @@ static inline unsigned long dma_get_merge_boundary(struct device *dev)
> > >  static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr,
> > >  		size_t size, enum dma_data_direction dir, unsigned long attrs)
> > >  {
> > > +	/* DMA must never operate on areas that might be remapped. */
> > > +	if (dev_WARN_ONCE(dev, is_vmalloc_addr(ptr),
> > > +			  "wanted %zu bytes mapped in vmalloc\n", size)) {
> > > +		return DMA_MAPPING_ERROR;
> > > +	}
> > 
> > That's a very odd error string, I know if I saw it for the first time, I
> > would have no idea what it meant.  The USB message at least gives you a
> > bit more context as to what went wrong and how to fix it.
> > 
> > How about something like "Memory is not DMA capabable, please fix the
> > allocation of it to be correct", or "non-dma-able memory was attempted
> > to be mapped, but this is impossible to to" or something else.
> 
> I've fixed the message to "rejecting DMA map of vmalloc memory" and
> applied the patch.

Looks good!  You can apply patch 2/2 as well if you want to take that
through your tree too.

thanks,

greg k-h

Re: [PATCH v4 1/2] dma-mapping: Add vmap checks to dma_map_single()

[Christoph Hellwig]

On Wed, Oct 30, 2019 at 08:26:40PM +0100, Greg Kroah-Hartman wrote:
> Looks good!  You can apply patch 2/2 as well if you want to take that
> through your tree too.

I can do that, I'll just need a formal ACK from you.

Re: [PATCH v4 2/2] usb: core: Remove redundant vmap checks

[Greg Kroah-Hartman]

On Tue, Oct 29, 2019 at 02:34:23PM -0700, Kees Cook wrote:
> Now that the vmap area checks are being performed in the DMA
> infrastructure directly, there is no need to repeat them in USB.
> 
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  drivers/usb/core/hcd.c | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Re: [PATCH v4 1/2] dma-mapping: Add vmap checks to dma_map_single()

[Greg Kroah-Hartman]

On Wed, Oct 30, 2019 at 08:45:32PM +0100, Christoph Hellwig wrote:
> On Wed, Oct 30, 2019 at 08:26:40PM +0100, Greg Kroah-Hartman wrote:
> > Looks good!  You can apply patch 2/2 as well if you want to take that
> > through your tree too.
> 
> I can do that, I'll just need a formal ACK from you.

Now sent, thanks.

Re: [PATCH v4 2/2] usb: core: Remove redundant vmap checks

[Christoph Hellwig]

Thanks,

applied to the dma-mapping for-next tree.