diff options
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 9 | ||||
| -rw-r--r-- | drivers/iommu/Kconfig | 19 | ||||
| -rw-r--r-- | drivers/iommu/Makefile | 1 | ||||
| -rw-r--r-- | drivers/iommu/iommu-debug-pagealloc.c | 32 | ||||
| -rw-r--r-- | include/linux/iommu-debug-pagealloc.h | 17 | ||||
| -rw-r--r-- | mm/page_ext.c | 4 |
6 files changed, 82 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index a8d0afde7f85..d484d9d8d0a4 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2675,6 +2675,15 @@ Kernel parameters 1 - Bypass the IOMMU for DMA. unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH. + iommu.debug_pagealloc= + [KNL,EARLY] When CONFIG_IOMMU_DEBUG_PAGEALLOC is set, this + parameter enables the feature at boot time. By default, it + is disabled and the system behaves the same way as a kernel + built without CONFIG_IOMMU_DEBUG_PAGEALLOC. + Format: { "0" | "1" } + 0 - Sanitizer disabled. + 1 - Sanitizer enabled, expect runtime overhead. + io7= [HW] IO7 for Marvel-based Alpha systems See comment before marvel_specify_io7 in arch/alpha/kernel/core_marvel.c. diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig index 99095645134f..f86262b11416 100644 --- a/drivers/iommu/Kconfig +++ b/drivers/iommu/Kconfig @@ -384,6 +384,25 @@ config SPRD_IOMMU Say Y here if you want to use the multimedia devices listed above. +config IOMMU_DEBUG_PAGEALLOC + bool "Debug IOMMU mappings against page allocations" + depends on DEBUG_PAGEALLOC && IOMMU_API && PAGE_EXTENSION + help + This enables a consistency check between the kernel page allocator and + the IOMMU subsystem. It verifies that pages being allocated or freed + are not currently mapped in any IOMMU domain. + + This helps detect DMA use-after-free bugs where a driver frees a page + but forgets to unmap it from the IOMMU, potentially allowing a device + to overwrite memory that the kernel has repurposed. + + These checks are best-effort and may not detect all problems. + + Due to performance overhead, this feature is disabled by default. + You must enable "iommu.debug_pagealloc" from the kernel command + line to activate the runtime checks. + + If unsure, say N. endif # IOMMU_SUPPORT source "drivers/iommu/generic_pt/Kconfig" diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile index 8e8843316c4b..0275821f4ef9 100644 --- a/drivers/iommu/Makefile +++ b/drivers/iommu/Makefile @@ -36,3 +36,4 @@ obj-$(CONFIG_IOMMU_SVA) += iommu-sva.o obj-$(CONFIG_IOMMU_IOPF) += io-pgfault.o obj-$(CONFIG_SPRD_IOMMU) += sprd-iommu.o obj-$(CONFIG_APPLE_DART) += apple-dart.o +obj-$(CONFIG_IOMMU_DEBUG_PAGEALLOC) += iommu-debug-pagealloc.o diff --git a/drivers/iommu/iommu-debug-pagealloc.c b/drivers/iommu/iommu-debug-pagealloc.c new file mode 100644 index 000000000000..4022e9af7f27 --- /dev/null +++ b/drivers/iommu/iommu-debug-pagealloc.c @@ -0,0 +1,32 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2025 - Google Inc + * Author: Mostafa Saleh <smostafa@google.com> + * IOMMU API debug page alloc sanitizer + */ +#include <linux/atomic.h> +#include <linux/iommu-debug-pagealloc.h> +#include <linux/kernel.h> +#include <linux/page_ext.h> + +static bool needed; + +struct iommu_debug_metadata { + atomic_t ref; +}; + +static __init bool need_iommu_debug(void) +{ + return needed; +} + +struct page_ext_operations page_iommu_debug_ops = { + .size = sizeof(struct iommu_debug_metadata), + .need = need_iommu_debug, +}; + +static int __init iommu_debug_pagealloc(char *str) +{ + return kstrtobool(str, &needed); +} +early_param("iommu.debug_pagealloc", iommu_debug_pagealloc); diff --git a/include/linux/iommu-debug-pagealloc.h b/include/linux/iommu-debug-pagealloc.h new file mode 100644 index 000000000000..83e64d70bf6c --- /dev/null +++ b/include/linux/iommu-debug-pagealloc.h @@ -0,0 +1,17 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2025 - Google Inc + * Author: Mostafa Saleh <smostafa@google.com> + * IOMMU API debug page alloc sanitizer + */ + +#ifndef __LINUX_IOMMU_DEBUG_PAGEALLOC_H +#define __LINUX_IOMMU_DEBUG_PAGEALLOC_H + +#ifdef CONFIG_IOMMU_DEBUG_PAGEALLOC + +extern struct page_ext_operations page_iommu_debug_ops; + +#endif /* CONFIG_IOMMU_DEBUG_PAGEALLOC */ + +#endif /* __LINUX_IOMMU_DEBUG_PAGEALLOC_H */ diff --git a/mm/page_ext.c b/mm/page_ext.c index d7396a8970e5..297e4cd8ce90 100644 --- a/mm/page_ext.c +++ b/mm/page_ext.c @@ -11,6 +11,7 @@ #include <linux/page_table_check.h> #include <linux/rcupdate.h> #include <linux/pgalloc_tag.h> +#include <linux/iommu-debug-pagealloc.h> /* * struct page extension @@ -89,6 +90,9 @@ static struct page_ext_operations *page_ext_ops[] __initdata = { #ifdef CONFIG_PAGE_TABLE_CHECK &page_table_check_ops, #endif +#ifdef CONFIG_IOMMU_DEBUG_PAGEALLOC + &page_iommu_debug_ops, +#endif }; unsigned long page_ext_size; |