[PATCH 09/32] kmsan: Introduce kmsan_memmove_metadata()

Ilya Leoshkevich
2023-11-15T20:35:18Z

It is useful to manually copy metadata in order to describe the effects
of memmove()-like logic in uninstrumented code or inline asm. Introduce
kmsan_memmove_metadata() for this purpose.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
include/linux/kmsan-checks.h | 14 ++++++++++++++
mm/kmsan/hooks.c | 11 +++++++++++
2 files changed, 25 insertions(+)

diff --git a/include/linux/kmsan-checks.h b/include/linux/kmsan-checks.h
index c4cae333deec..5218973f0ad0 100644
--- a/include/linux/kmsan-checks.h
+++ b/include/linux/kmsan-checks.h
@@ -61,6 +61,17 @@ void kmsan_check_memory(const void *address, size_t size);
void kmsan_copy_to_user(void __user *to, const void *from, size_t to_copy,
size_t left);

+/**
+ * kmsan_memmove_metadata() - Copy kernel memory range metadata.
+ * @dst: start of the destination kernel memory range.
+ * @src: start of the source kernel memory range.
+ * @n: size of the memory ranges.
+ *
+ * KMSAN will treat the destination range as if its contents were memmove()d
+ * from the source range.
+ */
+void kmsan_memmove_metadata(void *dst, const void *src, size_t n);
+
#else

static inline void kmsan_poison_memory(const void *address, size_t size,
@@ -77,6 +88,9 @@ static inline void kmsan_copy_to_user(void __user *to, const void *from,
size_t to_copy, size_t left)
{
}
+static inline void kmsan_memmove_metadata(void *dst, const void *src, size_t n)
+{
+}

#endif

diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c
index eafc45f937eb..4d477a0a356c 100644
--- a/mm/kmsan/hooks.c
+++ b/mm/kmsan/hooks.c
@@ -286,6 +286,17 @@ void kmsan_copy_to_user(void __user *to, const void *from, size_t to_copy,
}
EXPORT_SYMBOL(kmsan_copy_to_user);

+void kmsan_memmove_metadata(void *dst, const void *src, size_t n)
+{
+ if (!kmsan_enabled || kmsan_in_runtime())
+ return;
+
+ kmsan_enter_runtime();
+ kmsan_internal_memmove_metadata(dst, (void *)src, n);
+ kmsan_leave_runtime();
+}
+EXPORT_SYMBOL(kmsan_memmove_metadata);
+
/* Helper function to check an URB. */
void kmsan_handle_urb(const struct urb *urb, bool is_out)
{
--
2.41.0