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dma: kmsan: unpoison DMA mappings

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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: Alexander 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: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Alexander Potapenko 2022-09-15 17:03:55 +02:00 committed by Andrew Morton
parent 38317724f6
commit 7ade4f1077
3 changed files with 107 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
include/linux/kmsan.h
View File

@ -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 */

10
kernel/dma/mapping.c
View File

@ -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;
}

59
mm/kmsan/hooks.c
View File

@ -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)
{