Commit 7ade4f10 authored by Alexander Potapenko's avatar Alexander Potapenko Committed by Andrew Morton
Browse files

dma: kmsan: unpoison DMA mappings 

KMSAN doesn't know about DMA memory writes performed by devices.  We
unpoison such memory when it's mapped to avoid false positive reports.

Link: https://lkml.kernel.org/r/20220915150417.722975-22-glider@google.com


Signed-off-by: default avatarAlexander Potapenko <glider@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Marco Elver <elver@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 38317724

include/linux/kmsan.h

+41 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
#ifndef _LINUX_KMSAN_H

#define _LINUX_KMSAN_H



#include <linux/dma-direction.h>

#include <linux/gfp.h>

#include <linux/kmsan-checks.h>

#include <linux/types.h>
@@ -16,6 +17,7 @@ 
struct page;

struct kmem_cache;

struct task_struct;

struct scatterlist;



#ifdef CONFIG_KMSAN
@@ -172,6 +174,35 @@ void kmsan_ioremap_page_range(unsigned long addr, unsigned long end, 
 */

void kmsan_iounmap_page_range(unsigned long start, unsigned long end);



/**

 * kmsan_handle_dma() - Handle a DMA data transfer.

 * @page:   first page of the buffer.

 * @offset: offset of the buffer within the first page.

 * @size:   buffer size.

 * @dir:    one of possible dma_data_direction values.

 *

 * Depending on @direction, KMSAN:

 * * checks the buffer, if it is copied to device;

 * * initializes the buffer, if it is copied from device;

 * * does both, if this is a DMA_BIDIRECTIONAL transfer.

 */

void kmsan_handle_dma(struct page *page, size_t offset, size_t size,

		      enum dma_data_direction dir);



/**

 * kmsan_handle_dma_sg() - Handle a DMA transfer using scatterlist.

 * @sg:    scatterlist holding DMA buffers.

 * @nents: number of scatterlist entries.

 * @dir:   one of possible dma_data_direction values.

 *

 * Depending on @direction, KMSAN:

 * * checks the buffers in the scatterlist, if they are copied to device;

 * * initializes the buffers, if they are copied from device;

 * * does both, if this is a DMA_BIDIRECTIONAL transfer.

 */

void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,

			 enum dma_data_direction dir);



#else



static inline void kmsan_init_shadow(void)
@@ -254,6 +285,16 @@ static inline void kmsan_iounmap_page_range(unsigned long start, 
{

}



static inline void kmsan_handle_dma(struct page *page, size_t offset,

				    size_t size, enum dma_data_direction dir)

{

}



static inline void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,

				       enum dma_data_direction dir)

{

}



#endif



#endif /* _LINUX_KMSAN_H */

kernel/dma/mapping.c

+7 −3
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <linux/dma-map-ops.h>

#include <linux/export.h>

#include <linux/gfp.h>

#include <linux/kmsan.h>

#include <linux/of_device.h>

#include <linux/slab.h>

#include <linux/vmalloc.h>
@@ -156,6 +157,7 @@ dma_addr_t dma_map_page_attrs(struct device *dev, struct page *page, 
		addr = dma_direct_map_page(dev, page, offset, size, dir, attrs);

	else

		addr = ops->map_page(dev, page, offset, size, dir, attrs);

	kmsan_handle_dma(page, offset, size, dir);

	debug_dma_map_page(dev, page, offset, size, dir, addr, attrs);



	return addr;
@@ -194,11 +196,13 @@ static int __dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, 
	else

		ents = ops->map_sg(dev, sg, nents, dir, attrs);



	if (ents > 0)

	if (ents > 0) {

		kmsan_handle_dma_sg(sg, nents, dir);

		debug_dma_map_sg(dev, sg, nents, ents, dir, attrs);

	else if (WARN_ON_ONCE(ents != -EINVAL && ents != -ENOMEM &&

			      ents != -EIO && ents != -EREMOTEIO))

	} else if (WARN_ON_ONCE(ents != -EINVAL && ents != -ENOMEM &&

				ents != -EIO && ents != -EREMOTEIO)) {

		return -EIO;

	}



	return ents;

}

mm/kmsan/hooks.c

+59 −0
Original line number Diff line number Diff line
@@ -10,10 +10,12 @@ 
 */



#include <linux/cacheflush.h>

#include <linux/dma-direction.h>

#include <linux/gfp.h>

#include <linux/kmsan.h>

#include <linux/mm.h>

#include <linux/mm_types.h>

#include <linux/scatterlist.h>

#include <linux/slab.h>

#include <linux/uaccess.h>
@@ -243,6 +245,63 @@ void kmsan_copy_to_user(void __user *to, const void *from, size_t to_copy, 
}

EXPORT_SYMBOL(kmsan_copy_to_user);



static void kmsan_handle_dma_page(const void *addr, size_t size,

				  enum dma_data_direction dir)

{

	switch (dir) {

	case DMA_BIDIRECTIONAL:

		kmsan_internal_check_memory((void *)addr, size, /*user_addr*/ 0,

					    REASON_ANY);

		kmsan_internal_unpoison_memory((void *)addr, size,

					       /*checked*/ false);

		break;

	case DMA_TO_DEVICE:

		kmsan_internal_check_memory((void *)addr, size, /*user_addr*/ 0,

					    REASON_ANY);

		break;

	case DMA_FROM_DEVICE:

		kmsan_internal_unpoison_memory((void *)addr, size,

					       /*checked*/ false);

		break;

	case DMA_NONE:

		break;

	}

}



/* Helper function to handle DMA data transfers. */

void kmsan_handle_dma(struct page *page, size_t offset, size_t size,

		      enum dma_data_direction dir)

{

	u64 page_offset, to_go, addr;



	if (PageHighMem(page))

		return;

	addr = (u64)page_address(page) + offset;

	/*

	 * The kernel may occasionally give us adjacent DMA pages not belonging

	 * to the same allocation. Process them separately to avoid triggering

	 * internal KMSAN checks.

	 */

	while (size > 0) {

		page_offset = addr % PAGE_SIZE;

		to_go = min(PAGE_SIZE - page_offset, (u64)size);

		kmsan_handle_dma_page((void *)addr, to_go, dir);

		addr += to_go;

		size -= to_go;

	}

}



void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,

			 enum dma_data_direction dir)

{

	struct scatterlist *item;

	int i;



	for_each_sg(sg, item, nents, i)

		kmsan_handle_dma(sg_page(item), item->offset, item->length,

				 dir);

}



/* Functions from kmsan-checks.h follow. */

void kmsan_poison_memory(const void *address, size_t size, gfp_t flags)

{