Adds a smoke test to ensure that KASAN in Rust is actually detecting a
Rust-native UAF. There is significant room to expand this test suite,
but this will at least ensure that flags are having the intended effect.
The rename from kasan_test.c to kasan_test_c.c is in order to allow the
single kasan_test.ko test suite to contain both a .o file produced
by the C compiler and one produced by rustc.
Signed-off-by: Matthew Maurer <mmaurer@xxxxxxxxxx>
---
mm/kasan/Makefile | 7 ++++++-
mm/kasan/kasan.h | 6 ++++++
mm/kasan/{kasan_test.c => kasan_test_c.c} | 12 ++++++++++++
mm/kasan/kasan_test_rust.rs | 19 +++++++++++++++++++
4 files changed, 43 insertions(+), 1 deletion(-)
rename mm/kasan/{kasan_test.c => kasan_test_c.c} (99%)
create mode 100644 mm/kasan/kasan_test_rust.rs
diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
index 7634dd2a6128..13059d9ee13c 100644
--- a/mm/kasan/Makefile
+++ b/mm/kasan/Makefile
@@ -44,13 +44,18 @@ ifndef CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX
CFLAGS_KASAN_TEST += -fno-builtin
endif
-CFLAGS_kasan_test.o := $(CFLAGS_KASAN_TEST)
+CFLAGS_kasan_test_c.o := $(CFLAGS_KASAN_TEST)
+RUSTFLAGS_kasan_test_rust.o := $(RUSTFLAGS_KASAN)
CFLAGS_kasan_test_module.o := $(CFLAGS_KASAN_TEST)
obj-y := common.o report.o
obj-$(CONFIG_KASAN_GENERIC) += init.o generic.o report_generic.o shadow.o quarantine.o
obj-$(CONFIG_KASAN_HW_TAGS) += hw_tags.o report_hw_tags.o tags.o report_tags.o
obj-$(CONFIG_KASAN_SW_TAGS) += init.o report_sw_tags.o shadow.o sw_tags.o tags.o report_tags.o
+kasan_test-objs := kasan_test_c.o
+ifdef CONFIG_RUST
+ kasan_test-objs += kasan_test_rust.o
+endif
obj-$(CONFIG_KASAN_KUNIT_TEST) += kasan_test.o
obj-$(CONFIG_KASAN_MODULE_TEST) += kasan_test_module.o
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index fb2b9ac0659a..f438a6cdc964 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -555,6 +555,12 @@ static inline bool kasan_arch_is_ready(void) { return true; }
void kasan_kunit_test_suite_start(void);
void kasan_kunit_test_suite_end(void);
+#ifdef CONFIG_RUST
+char kasan_test_rust_uaf(void);
+#else
+static inline char kasan_test_rust_uaf(void) { return '\0'; }
+#endif
+
#else /* CONFIG_KASAN_KUNIT_TEST */
static inline void kasan_kunit_test_suite_start(void) { }
diff --git a/mm/kasan/kasan_test.c b/mm/kasan/kasan_test_c.c
similarity index 99%
rename from mm/kasan/kasan_test.c
rename to mm/kasan/kasan_test_c.c
index 7b32be2a3cf0..dd3d2a1e3145 100644
--- a/mm/kasan/kasan_test.c
+++ b/mm/kasan/kasan_test_c.c
@@ -1899,6 +1899,17 @@ static void match_all_mem_tag(struct kunit *test)
kfree(ptr);
}
+/*
+ * Check that Rust performing a use-after-free using `unsafe` is detected.
+ * This is a smoke test to make sure that Rust is being sanitized properly.
+ */
+static void rust_uaf(struct kunit *test)
+{
+ KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_RUST);
+ KUNIT_EXPECT_KASAN_FAIL(test, kasan_test_rust_uaf());
+}
+
+
static struct kunit_case kasan_kunit_test_cases[] = {
KUNIT_CASE(kmalloc_oob_right),
KUNIT_CASE(kmalloc_oob_left),
@@ -1971,6 +1982,7 @@ static struct kunit_case kasan_kunit_test_cases[] = {
KUNIT_CASE(match_all_not_assigned),
KUNIT_CASE(match_all_ptr_tag),
KUNIT_CASE(match_all_mem_tag),
+ KUNIT_CASE(rust_uaf),
{}
};
diff --git a/mm/kasan/kasan_test_rust.rs b/mm/kasan/kasan_test_rust.rs
new file mode 100644
index 000000000000..7239303b232c
--- /dev/null
+++ b/mm/kasan/kasan_test_rust.rs
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Helper crate for KASAN testing
+//! Provides behavior to check the sanitization of Rust code.
+use kernel::prelude::*;
+use core::ptr::addr_of_mut;
+
+/// Trivial UAF - allocate a big vector, grab a pointer partway through,
+/// drop the vector, and touch it.
+#[no_mangle]
+pub extern "C" fn kasan_test_rust_uaf() -> u8 {
+ let mut v: Vec<u8> = Vec::new();
+ for _ in 0..4096 {
+ v.push(0x42, GFP_KERNEL).unwrap();
+ }
+ let ptr: *mut u8 = addr_of_mut!(v[2048]);
+ drop(v);
+ unsafe { *ptr }
+}
--
2.46.0.184.g6999bdac58-goog
