Hi,
This builds on the proposal[1] from Mark and lets me convert the
existing usercopy selftest to KUnit. Besides adding this basic test to
the KUnit collection, it also opens the door for execve testing (which
depends on having a functional current->mm), and should provide the
basic infrastructure for adding Mark's much more complete usercopy tests.
v3:
- use MEMEQ KUnit helper (David)
- exclude pathological address confusion test for systems with separate
address spaces, noticed by David
- add KUnit-conditional exports for alloc_mm() and arch_pick_mmap_layout()
noticed by 0day
v2: https://lore.kernel.org/lkml/[email protected]/
v1: https://lore.kernel.org/lkml/[email protected]/
-Kees
[1] https://lore.kernel.org/lkml/[email protected]/
Kees Cook (2):
kunit: test: Add vm_mmap() allocation resource manager
usercopy: Convert test_user_copy to KUnit test
MAINTAINERS | 1 +
include/kunit/test.h | 17 ++
kernel/fork.c | 3 +
lib/Kconfig.debug | 21 +-
lib/Makefile | 2 +-
lib/kunit/Makefile | 1 +
lib/kunit/user_alloc.c | 113 +++++++++
lib/{test_user_copy.c => usercopy_kunit.c} | 282 ++++++++++-----------
mm/util.c | 3 +
9 files changed, 288 insertions(+), 155 deletions(-)
create mode 100644 lib/kunit/user_alloc.c
rename lib/{test_user_copy.c => usercopy_kunit.c} (46%)
--
2.34.1
For tests that need to allocate using vm_mmap() (e.g. usercopy and
execve), provide the interface to have the allocation tracked by KUnit
itself. This requires bringing up a placeholder userspace mm.
This combines my earlier attempt at this with Mark Rutland's version[1].
Normally alloc_mm() and arch_pick_mmap_layout() aren't exported for
modules, so export these only for KUnit testing.
Link: https://lore.kernel.org/lkml/[email protected]/ [1]
Co-developed-by: Mark Rutland <[email protected]>
Signed-off-by: Mark Rutland <[email protected]>
Reviewed-by: David Gow <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
---
include/kunit/test.h | 17 +++++++
kernel/fork.c | 3 ++
lib/kunit/Makefile | 1 +
lib/kunit/user_alloc.c | 113 +++++++++++++++++++++++++++++++++++++++++
mm/util.c | 3 ++
5 files changed, 137 insertions(+)
create mode 100644 lib/kunit/user_alloc.c
diff --git a/include/kunit/test.h b/include/kunit/test.h
index e32b4cb7afa2..ec61cad6b71d 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -480,6 +480,23 @@ static inline void *kunit_kcalloc(struct kunit *test, size_t n, size_t size, gfp
return kunit_kmalloc_array(test, n, size, gfp | __GFP_ZERO);
}
+/**
+ * kunit_vm_mmap() - Allocate KUnit-tracked vm_mmap() area
+ * @test: The test context object.
+ * @file: struct file pointer to map from, if any
+ * @addr: desired address, if any
+ * @len: how many bytes to allocate
+ * @prot: mmap PROT_* bits
+ * @flag: mmap flags
+ * @offset: offset into @file to start mapping from.
+ *
+ * See vm_mmap() for more information.
+ */
+unsigned long kunit_vm_mmap(struct kunit *test, struct file *file,
+ unsigned long addr, unsigned long len,
+ unsigned long prot, unsigned long flag,
+ unsigned long offset);
+
void kunit_cleanup(struct kunit *test);
void __printf(2, 3) kunit_log_append(struct string_stream *log, const char *fmt, ...);
diff --git a/kernel/fork.c b/kernel/fork.c
index 99076dbe27d8..cea203197136 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -115,6 +115,8 @@
#define CREATE_TRACE_POINTS
#include <trace/events/task.h>
+#include <kunit/visibility.h>
+
/*
* Minimum number of threads to boot the kernel
*/
@@ -1334,6 +1336,7 @@ struct mm_struct *mm_alloc(void)
memset(mm, 0, sizeof(*mm));
return mm_init(mm, current, current_user_ns());
}
+EXPORT_SYMBOL_IF_KUNIT(mm_alloc);
static inline void __mmput(struct mm_struct *mm)
{
diff --git a/lib/kunit/Makefile b/lib/kunit/Makefile
index 309659a32a78..56dd67dc6e57 100644
--- a/lib/kunit/Makefile
+++ b/lib/kunit/Makefile
@@ -2,6 +2,7 @@ obj-$(CONFIG_KUNIT) += kunit.o
kunit-objs += test.o \
resource.o \
+ user_alloc.o \
static_stub.o \
string-stream.o \
assert.o \
diff --git a/lib/kunit/user_alloc.c b/lib/kunit/user_alloc.c
new file mode 100644
index 000000000000..76d3d1345ed7
--- /dev/null
+++ b/lib/kunit/user_alloc.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit userspace memory allocation resource management.
+ */
+#include <kunit/resource.h>
+#include <kunit/test.h>
+#include <linux/kthread.h>
+#include <linux/mm.h>
+
+struct kunit_vm_mmap_resource {
+ unsigned long addr;
+ size_t size;
+};
+
+/* vm_mmap() arguments */
+struct kunit_vm_mmap_params {
+ struct file *file;
+ unsigned long addr;
+ unsigned long len;
+ unsigned long prot;
+ unsigned long flag;
+ unsigned long offset;
+};
+
+/* Create and attach a new mm if it doesn't already exist. */
+static int kunit_attach_mm(void)
+{
+ struct mm_struct *mm;
+
+ if (current->mm)
+ return 0;
+
+ mm = mm_alloc();
+ if (!mm)
+ return -ENOMEM;
+
+ /* Define the task size. */
+ mm->task_size = TASK_SIZE;
+
+ /* Make sure we can allocate new VMAs. */
+ arch_pick_mmap_layout(mm, ¤t->signal->rlim[RLIMIT_STACK]);
+
+ /* Attach the mm. It will be cleaned up when the process dies. */
+ kthread_use_mm(mm);
+
+ return 0;
+}
+
+static int kunit_vm_mmap_init(struct kunit_resource *res, void *context)
+{
+ struct kunit_vm_mmap_params *p = context;
+ struct kunit_vm_mmap_resource vres;
+ int ret;
+
+ ret = kunit_attach_mm();
+ if (ret)
+ return ret;
+
+ vres.size = p->len;
+ vres.addr = vm_mmap(p->file, p->addr, p->len, p->prot, p->flag, p->offset);
+ if (!vres.addr)
+ return -ENOMEM;
+ res->data = kmemdup(&vres, sizeof(vres), GFP_KERNEL);
+ if (!res->data) {
+ vm_munmap(vres.addr, vres.size);
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static void kunit_vm_mmap_free(struct kunit_resource *res)
+{
+ struct kunit_vm_mmap_resource *vres = res->data;
+
+ /*
+ * Since this is executed from the test monitoring process,
+ * the test's mm has already been torn down. We don't need
+ * to run vm_munmap(vres->addr, vres->size), only clean up
+ * the vres.
+ */
+
+ kfree(vres);
+ res->data = NULL;
+}
+
+unsigned long kunit_vm_mmap(struct kunit *test, struct file *file,
+ unsigned long addr, unsigned long len,
+ unsigned long prot, unsigned long flag,
+ unsigned long offset)
+{
+ struct kunit_vm_mmap_params params = {
+ .file = file,
+ .addr = addr,
+ .len = len,
+ .prot = prot,
+ .flag = flag,
+ .offset = offset,
+ };
+ struct kunit_vm_mmap_resource *vres;
+
+ vres = kunit_alloc_resource(test,
+ kunit_vm_mmap_init,
+ kunit_vm_mmap_free,
+ GFP_KERNEL,
+ ¶ms);
+ if (vres)
+ return vres->addr;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(kunit_vm_mmap);
+
+MODULE_IMPORT_NS(EXPORTED_FOR_KUNIT_TESTING);
diff --git a/mm/util.c b/mm/util.c
index c9e519e6811f..df37c47d9374 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -26,6 +26,8 @@
#include <linux/uaccess.h>
+#include <kunit/visibility.h>
+
#include "internal.h"
#include "swap.h"
@@ -482,6 +484,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
clear_bit(MMF_TOPDOWN, &mm->flags);
}
#endif
+EXPORT_SYMBOL_IF_KUNIT(arch_pick_mmap_layout);
/**
* __account_locked_vm - account locked pages to an mm's locked_vm
--
2.34.1
Convert the runtime tests of hardened usercopy to standard KUnit tests.
Additionally disable usercopy_test_invalid() for systems with separate
address spaces (or no MMU) since it's not sensible to test for address
confusion there (e.g. m68k).
Co-developed-by: Vitor Massaru Iha <[email protected]>
Signed-off-by: Vitor Massaru Iha <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Tested-by: Ivan Orlov <[email protected]>
Reviewed-by: David Gow <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
---
MAINTAINERS | 1 +
lib/Kconfig.debug | 21 +-
lib/Makefile | 2 +-
lib/{test_user_copy.c => usercopy_kunit.c} | 282 ++++++++++-----------
4 files changed, 151 insertions(+), 155 deletions(-)
rename lib/{test_user_copy.c => usercopy_kunit.c} (46%)
diff --git a/MAINTAINERS b/MAINTAINERS
index 8754ac2c259d..0cd171ec6010 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11962,6 +11962,7 @@ F: arch/*/configs/hardening.config
F: include/linux/overflow.h
F: include/linux/randomize_kstack.h
F: kernel/configs/hardening.config
+F: lib/usercopy_kunit.c
F: mm/usercopy.c
K: \b(add|choose)_random_kstack_offset\b
K: \b__check_(object_size|heap_object)\b
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 59b6765d86b8..561e346f5cb0 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2505,18 +2505,6 @@ config TEST_VMALLOC
If unsure, say N.
-config TEST_USER_COPY
- tristate "Test user/kernel boundary protections"
- depends on m
- help
- This builds the "test_user_copy" module that runs sanity checks
- on the copy_to/from_user infrastructure, making sure basic
- user/kernel boundary testing is working. If it fails to load,
- a regression has been detected in the user/kernel memory boundary
- protections.
-
- If unsure, say N.
-
config TEST_BPF
tristate "Test BPF filter functionality"
depends on m && NET
@@ -2814,6 +2802,15 @@ config SIPHASH_KUNIT_TEST
This is intended to help people writing architecture-specific
optimized versions. If unsure, say N.
+config USERCOPY_KUNIT_TEST
+ tristate "KUnit Test for user/kernel boundary protections"
+ depends on KUNIT
+ default KUNIT_ALL_TESTS
+ help
+ This builds the "usercopy_kunit" module that runs sanity checks
+ on the copy_to/from_user infrastructure, making sure basic
+ user/kernel boundary testing is working.
+
config TEST_UDELAY
tristate "udelay test driver"
help
diff --git a/lib/Makefile b/lib/Makefile
index 3b1769045651..fae5cc67b95a 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -78,7 +78,6 @@ obj-$(CONFIG_TEST_LKM) += test_module.o
obj-$(CONFIG_TEST_VMALLOC) += test_vmalloc.o
obj-$(CONFIG_TEST_RHASHTABLE) += test_rhashtable.o
obj-$(CONFIG_TEST_SORT) += test_sort.o
-obj-$(CONFIG_TEST_USER_COPY) += test_user_copy.o
obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_keys.o
obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_key_base.o
obj-$(CONFIG_TEST_DYNAMIC_DEBUG) += test_dynamic_debug.o
@@ -388,6 +387,7 @@ CFLAGS_fortify_kunit.o += $(call cc-disable-warning, stringop-truncation)
CFLAGS_fortify_kunit.o += $(DISABLE_STRUCTLEAK_PLUGIN)
obj-$(CONFIG_FORTIFY_KUNIT_TEST) += fortify_kunit.o
obj-$(CONFIG_SIPHASH_KUNIT_TEST) += siphash_kunit.o
+obj-$(CONFIG_USERCOPY_KUNIT_TEST) += usercopy_kunit.o
obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o
diff --git a/lib/test_user_copy.c b/lib/usercopy_kunit.c
similarity index 46%
rename from lib/test_user_copy.c
rename to lib/usercopy_kunit.c
index 5ff04d8fe971..45f1e558c464 100644
--- a/lib/test_user_copy.c
+++ b/lib/usercopy_kunit.c
@@ -15,7 +15,7 @@
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
-#include <linux/vmalloc.h>
+#include <kunit/test.h>
/*
* Several 32-bit architectures support 64-bit {get,put}_user() calls.
@@ -31,26 +31,27 @@
# define TEST_U64
#endif
-#define test(condition, msg, ...) \
-({ \
- int cond = (condition); \
- if (cond) \
- pr_warn("[%d] " msg "\n", __LINE__, ##__VA_ARGS__); \
- cond; \
-})
+struct usercopy_test_priv {
+ char *kmem;
+ char __user *umem;
+ size_t size;
+};
static bool is_zeroed(void *from, size_t size)
{
return memchr_inv(from, 0x0, size) == NULL;
}
-static int test_check_nonzero_user(char *kmem, char __user *umem, size_t size)
+/* Test usage of check_nonzero_user(). */
+static void usercopy_test_check_nonzero_user(struct kunit *test)
{
- int ret = 0;
size_t start, end, i, zero_start, zero_end;
+ struct usercopy_test_priv *priv = test->priv;
+ char __user *umem = priv->umem;
+ char *kmem = priv->kmem;
+ size_t size = priv->size;
- if (test(size < 2 * PAGE_SIZE, "buffer too small"))
- return -EINVAL;
+ KUNIT_ASSERT_GE_MSG(test, size, 2 * PAGE_SIZE, "buffer too small");
/*
* We want to cross a page boundary to exercise the code more
@@ -84,8 +85,8 @@ static int test_check_nonzero_user(char *kmem, char __user *umem, size_t size)
for (i = zero_end; i < size; i += 2)
kmem[i] = 0xff;
- ret |= test(copy_to_user(umem, kmem, size),
- "legitimate copy_to_user failed");
+ KUNIT_EXPECT_EQ_MSG(test, copy_to_user(umem, kmem, size), 0,
+ "legitimate copy_to_user failed");
for (start = 0; start <= size; start++) {
for (end = start; end <= size; end++) {
@@ -93,35 +94,32 @@ static int test_check_nonzero_user(char *kmem, char __user *umem, size_t size)
int retval = check_zeroed_user(umem + start, len);
int expected = is_zeroed(kmem + start, len);
- ret |= test(retval != expected,
- "check_nonzero_user(=%d) != memchr_inv(=%d) mismatch (start=%zu, end=%zu)",
- retval, expected, start, end);
+ KUNIT_ASSERT_EQ_MSG(test, retval, expected,
+ "check_nonzero_user(=%d) != memchr_inv(=%d) mismatch (start=%zu, end=%zu)",
+ retval, expected, start, end);
}
}
-
- return ret;
}
-static int test_copy_struct_from_user(char *kmem, char __user *umem,
- size_t size)
+/* Test usage of copy_struct_from_user(). */
+static void usercopy_test_copy_struct_from_user(struct kunit *test)
{
- int ret = 0;
char *umem_src = NULL, *expected = NULL;
+ struct usercopy_test_priv *priv = test->priv;
+ char __user *umem = priv->umem;
+ char *kmem = priv->kmem;
+ size_t size = priv->size;
size_t ksize, usize;
- umem_src = kmalloc(size, GFP_KERNEL);
- ret = test(umem_src == NULL, "kmalloc failed");
- if (ret)
- goto out_free;
+ umem_src = kunit_kmalloc(test, size, GFP_KERNEL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, umem_src);
- expected = kmalloc(size, GFP_KERNEL);
- ret = test(expected == NULL, "kmalloc failed");
- if (ret)
- goto out_free;
+ expected = kunit_kmalloc(test, size, GFP_KERNEL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, expected);
/* Fill umem with a fixed byte pattern. */
memset(umem_src, 0x3e, size);
- ret |= test(copy_to_user(umem, umem_src, size),
+ KUNIT_ASSERT_EQ_MSG(test, copy_to_user(umem, umem_src, size), 0,
"legitimate copy_to_user failed");
/* Check basic case -- (usize == ksize). */
@@ -131,9 +129,9 @@ static int test_copy_struct_from_user(char *kmem, char __user *umem,
memcpy(expected, umem_src, ksize);
memset(kmem, 0x0, size);
- ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
+ KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0,
"copy_struct_from_user(usize == ksize) failed");
- ret |= test(memcmp(kmem, expected, ksize),
+ KUNIT_EXPECT_MEMEQ_MSG(test, kmem, expected, ksize,
"copy_struct_from_user(usize == ksize) gives unexpected copy");
/* Old userspace case -- (usize < ksize). */
@@ -144,9 +142,9 @@ static int test_copy_struct_from_user(char *kmem, char __user *umem,
memset(expected + usize, 0x0, ksize - usize);
memset(kmem, 0x0, size);
- ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
+ KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0,
"copy_struct_from_user(usize < ksize) failed");
- ret |= test(memcmp(kmem, expected, ksize),
+ KUNIT_EXPECT_MEMEQ_MSG(test, kmem, expected, ksize,
"copy_struct_from_user(usize < ksize) gives unexpected copy");
/* New userspace (-E2BIG) case -- (usize > ksize). */
@@ -154,7 +152,7 @@ static int test_copy_struct_from_user(char *kmem, char __user *umem,
usize = size;
memset(kmem, 0x0, size);
- ret |= test(copy_struct_from_user(kmem, ksize, umem, usize) != -E2BIG,
+ KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), -E2BIG,
"copy_struct_from_user(usize > ksize) didn't give E2BIG");
/* New userspace (success) case -- (usize > ksize). */
@@ -162,78 +160,46 @@ static int test_copy_struct_from_user(char *kmem, char __user *umem,
usize = size;
memcpy(expected, umem_src, ksize);
- ret |= test(clear_user(umem + ksize, usize - ksize),
+ KUNIT_EXPECT_EQ_MSG(test, clear_user(umem + ksize, usize - ksize), 0,
"legitimate clear_user failed");
memset(kmem, 0x0, size);
- ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
+ KUNIT_EXPECT_EQ_MSG(test, copy_struct_from_user(kmem, ksize, umem, usize), 0,
"copy_struct_from_user(usize > ksize) failed");
- ret |= test(memcmp(kmem, expected, ksize),
+ KUNIT_EXPECT_MEMEQ_MSG(test, kmem, expected, ksize,
"copy_struct_from_user(usize > ksize) gives unexpected copy");
-
-out_free:
- kfree(expected);
- kfree(umem_src);
- return ret;
}
-static int __init test_user_copy_init(void)
+/*
+ * Legitimate usage: none of these copies should fail.
+ */
+static void usercopy_test_valid(struct kunit *test)
{
- int ret = 0;
- char *kmem;
- char __user *usermem;
- char *bad_usermem;
- unsigned long user_addr;
- u8 val_u8;
- u16 val_u16;
- u32 val_u32;
-#ifdef TEST_U64
- u64 val_u64;
-#endif
+ struct usercopy_test_priv *priv = test->priv;
+ char __user *usermem = priv->umem;
+ char *kmem = priv->kmem;
- kmem = kmalloc(PAGE_SIZE * 2, GFP_KERNEL);
- if (!kmem)
- return -ENOMEM;
-
- user_addr = vm_mmap(NULL, 0, PAGE_SIZE * 2,
- PROT_READ | PROT_WRITE | PROT_EXEC,
- MAP_ANONYMOUS | MAP_PRIVATE, 0);
- if (user_addr >= (unsigned long)(TASK_SIZE)) {
- pr_warn("Failed to allocate user memory\n");
- kfree(kmem);
- return -ENOMEM;
- }
-
- usermem = (char __user *)user_addr;
- bad_usermem = (char *)user_addr;
-
- /*
- * Legitimate usage: none of these copies should fail.
- */
memset(kmem, 0x3a, PAGE_SIZE * 2);
- ret |= test(copy_to_user(usermem, kmem, PAGE_SIZE),
- "legitimate copy_to_user failed");
+ KUNIT_EXPECT_EQ_MSG(test, 0, copy_to_user(usermem, kmem, PAGE_SIZE),
+ "legitimate copy_to_user failed");
memset(kmem, 0x0, PAGE_SIZE);
- ret |= test(copy_from_user(kmem, usermem, PAGE_SIZE),
- "legitimate copy_from_user failed");
- ret |= test(memcmp(kmem, kmem + PAGE_SIZE, PAGE_SIZE),
- "legitimate usercopy failed to copy data");
-
-#define test_legit(size, check) \
- do { \
- val_##size = check; \
- ret |= test(put_user(val_##size, (size __user *)usermem), \
- "legitimate put_user (" #size ") failed"); \
- val_##size = 0; \
- ret |= test(get_user(val_##size, (size __user *)usermem), \
- "legitimate get_user (" #size ") failed"); \
- ret |= test(val_##size != check, \
- "legitimate get_user (" #size ") failed to do copy"); \
- if (val_##size != check) { \
- pr_info("0x%llx != 0x%llx\n", \
- (unsigned long long)val_##size, \
- (unsigned long long)check); \
- } \
+ KUNIT_EXPECT_EQ_MSG(test, 0, copy_from_user(kmem, usermem, PAGE_SIZE),
+ "legitimate copy_from_user failed");
+ KUNIT_EXPECT_MEMEQ_MSG(test, kmem, kmem + PAGE_SIZE, PAGE_SIZE,
+ "legitimate usercopy failed to copy data");
+
+#define test_legit(size, check) \
+ do { \
+ size val_##size = (check); \
+ KUNIT_EXPECT_EQ_MSG(test, 0, \
+ put_user(val_##size, (size __user *)usermem), \
+ "legitimate put_user (" #size ") failed"); \
+ val_##size = 0; \
+ KUNIT_EXPECT_EQ_MSG(test, 0, \
+ get_user(val_##size, (size __user *)usermem), \
+ "legitimate get_user (" #size ") failed"); \
+ KUNIT_EXPECT_EQ_MSG(test, val_##size, check, \
+ "legitimate get_user (" #size ") failed to do copy"); \
} while (0)
test_legit(u8, 0x5a);
@@ -243,27 +209,36 @@ static int __init test_user_copy_init(void)
test_legit(u64, 0x5a5b5c5d6a6b6c6d);
#endif
#undef test_legit
+}
- /* Test usage of check_nonzero_user(). */
- ret |= test_check_nonzero_user(kmem, usermem, 2 * PAGE_SIZE);
- /* Test usage of copy_struct_from_user(). */
- ret |= test_copy_struct_from_user(kmem, usermem, 2 * PAGE_SIZE);
-
- /*
- * Invalid usage: none of these copies should succeed.
- */
+/*
+ * Invalid usage: none of these copies should succeed.
+ */
+static void usercopy_test_invalid(struct kunit *test)
+{
+ struct usercopy_test_priv *priv = test->priv;
+ char __user *usermem = priv->umem;
+ char *bad_usermem = (char *)usermem;
+ char *kmem = priv->kmem;
+ u64 *kmem_u64 = (u64 *)kmem;
+
+ if (IS_ENABLED(CONFIG_ALTERNATE_USER_ADDRESS_SPACE) ||
+ !IS_ENABLED(CONFIG_MMU)) {
+ kunit_skip(test, "Testing for kernel/userspace address confusion is only sensible on architectures with a shared address space");
+ return;
+ }
/* Prepare kernel memory with check values. */
memset(kmem, 0x5a, PAGE_SIZE);
memset(kmem + PAGE_SIZE, 0, PAGE_SIZE);
/* Reject kernel-to-kernel copies through copy_from_user(). */
- ret |= test(!copy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE),
- PAGE_SIZE),
+ KUNIT_EXPECT_NE_MSG(test, copy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE),
+ PAGE_SIZE), 0,
"illegal all-kernel copy_from_user passed");
/* Destination half of buffer should have been zeroed. */
- ret |= test(memcmp(kmem + PAGE_SIZE, kmem, PAGE_SIZE),
+ KUNIT_EXPECT_MEMEQ_MSG(test, kmem + PAGE_SIZE, kmem, PAGE_SIZE,
"zeroing failure for illegal all-kernel copy_from_user");
#if 0
@@ -273,30 +248,32 @@ static int __init test_user_copy_init(void)
* to be tested in LKDTM instead, since this test module does not
* expect to explode.
*/
- ret |= test(!copy_from_user(bad_usermem, (char __user *)kmem,
- PAGE_SIZE),
+ KUNIT_EXPECT_NE_MSG(test, copy_from_user(bad_usermem, (char __user *)kmem,
+ PAGE_SIZE), 0,
"illegal reversed copy_from_user passed");
#endif
- ret |= test(!copy_to_user((char __user *)kmem, kmem + PAGE_SIZE,
- PAGE_SIZE),
+ KUNIT_EXPECT_NE_MSG(test, copy_to_user((char __user *)kmem, kmem + PAGE_SIZE,
+ PAGE_SIZE), 0,
"illegal all-kernel copy_to_user passed");
- ret |= test(!copy_to_user((char __user *)kmem, bad_usermem,
- PAGE_SIZE),
+
+ KUNIT_EXPECT_NE_MSG(test, copy_to_user((char __user *)kmem, bad_usermem,
+ PAGE_SIZE), 0,
"illegal reversed copy_to_user passed");
-#define test_illegal(size, check) \
- do { \
- val_##size = (check); \
- ret |= test(!get_user(val_##size, (size __user *)kmem), \
- "illegal get_user (" #size ") passed"); \
- ret |= test(val_##size != (size)0, \
- "zeroing failure for illegal get_user (" #size ")"); \
- if (val_##size != (size)0) { \
- pr_info("0x%llx != 0\n", \
- (unsigned long long)val_##size); \
- } \
- ret |= test(!put_user(val_##size, (size __user *)kmem), \
- "illegal put_user (" #size ") passed"); \
+#define test_illegal(size, check) \
+ do { \
+ size val_##size = (check); \
+ /* get_user() */ \
+ KUNIT_EXPECT_NE_MSG(test, get_user(val_##size, (size __user *)kmem), 0, \
+ "illegal get_user (" #size ") passed"); \
+ KUNIT_EXPECT_EQ_MSG(test, val_##size, 0, \
+ "zeroing failure for illegal get_user (" #size ")"); \
+ /* put_user() */ \
+ *kmem_u64 = 0xF09FA4AFF09FA4AF; \
+ KUNIT_EXPECT_NE_MSG(test, put_user(val_##size, (size __user *)kmem), 0, \
+ "illegal put_user (" #size ") passed"); \
+ KUNIT_EXPECT_EQ_MSG(test, *kmem_u64, 0xF09FA4AFF09FA4AF, \
+ "illegal put_user (" #size ") wrote to kernel memory!"); \
} while (0)
test_illegal(u8, 0x5a);
@@ -306,26 +283,47 @@ static int __init test_user_copy_init(void)
test_illegal(u64, 0x5a5b5c5d6a6b6c6d);
#endif
#undef test_illegal
+}
- vm_munmap(user_addr, PAGE_SIZE * 2);
- kfree(kmem);
+static int usercopy_test_init(struct kunit *test)
+{
+ struct usercopy_test_priv *priv;
+ unsigned long user_addr;
- if (ret == 0) {
- pr_info("tests passed.\n");
- return 0;
- }
+ priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);
+ test->priv = priv;
+ priv->size = PAGE_SIZE * 2;
- return -EINVAL;
-}
+ priv->kmem = kunit_kmalloc(test, priv->size, GFP_KERNEL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv->kmem);
-module_init(test_user_copy_init);
+ user_addr = kunit_vm_mmap(test, NULL, 0, priv->size,
+ PROT_READ | PROT_WRITE | PROT_EXEC,
+ MAP_ANONYMOUS | MAP_PRIVATE, 0);
+ KUNIT_ASSERT_NE_MSG(test, user_addr, 0,
+ "Could not create userspace mm");
+ KUNIT_ASSERT_LT_MSG(test, user_addr, (unsigned long)TASK_SIZE,
+ "Failed to allocate user memory");
+ priv->umem = (char __user *)user_addr;
-static void __exit test_user_copy_exit(void)
-{
- pr_info("unloaded.\n");
+ return 0;
}
-module_exit(test_user_copy_exit);
-
-MODULE_AUTHOR("Kees Cook <[email protected]>");
+static struct kunit_case usercopy_test_cases[] = {
+ KUNIT_CASE(usercopy_test_valid),
+ KUNIT_CASE(usercopy_test_invalid),
+ KUNIT_CASE(usercopy_test_check_nonzero_user),
+ KUNIT_CASE(usercopy_test_copy_struct_from_user),
+ {}
+};
+
+static struct kunit_suite usercopy_test_suite = {
+ .name = "usercopy",
+ .init = usercopy_test_init,
+ .test_cases = usercopy_test_cases,
+};
+
+kunit_test_suites(&usercopy_test_suite);
+MODULE_AUTHOR("Kees Cook <[email protected]>");
MODULE_LICENSE("GPL");
--
2.34.1
On Thu, 13 Jun 2024 at 03:59, Kees Cook <[email protected]> wrote:
>
> Hi,
>
> This builds on the proposal[1] from Mark and lets me convert the
> existing usercopy selftest to KUnit. Besides adding this basic test to
> the KUnit collection, it also opens the door for execve testing (which
> depends on having a functional current->mm), and should provide the
> basic infrastructure for adding Mark's much more complete usercopy tests.
>
> v3:
> - use MEMEQ KUnit helper (David)
> - exclude pathological address confusion test for systems with separate
> address spaces, noticed by David
> - add KUnit-conditional exports for alloc_mm() and arch_pick_mmap_layout()
> noticed by 0day
> v2: https://lore.kernel.org/lkml/[email protected]/
> v1: https://lore.kernel.org/lkml/[email protected]/
>
> -Kees
>
> [1] https://lore.kernel.org/lkml/[email protected]/
Thanks! This looks good to me (and passes everything here). Unless
there's a compelling reason not to, I think we can take this via the
KUnit tree.
Cheers,
-- David
On Thu, Jun 13, 2024 at 12:41:43PM +0800, David Gow wrote:
> On Thu, 13 Jun 2024 at 03:59, Kees Cook <[email protected]> wrote:
> >
> > Hi,
> >
> > This builds on the proposal[1] from Mark and lets me convert the
> > existing usercopy selftest to KUnit. Besides adding this basic test to
> > the KUnit collection, it also opens the door for execve testing (which
> > depends on having a functional current->mm), and should provide the
> > basic infrastructure for adding Mark's much more complete usercopy tests.
> >
> > v3:
> > - use MEMEQ KUnit helper (David)
> > - exclude pathological address confusion test for systems with separate
> > address spaces, noticed by David
> > - add KUnit-conditional exports for alloc_mm() and arch_pick_mmap_layout()
> > noticed by 0day
> > v2: https://lore.kernel.org/lkml/[email protected]/
> > v1: https://lore.kernel.org/lkml/[email protected]/
> >
> > -Kees
> >
> > [1] https://lore.kernel.org/lkml/[email protected]/
>
> Thanks! This looks good to me (and passes everything here). Unless
> there's a compelling reason not to, I think we can take this via the
> KUnit tree.
That would be lovely, thank you! :)
--
Kees Cook
On 6/12/24 13:59, Kees Cook wrote:
> Convert the runtime tests of hardened usercopy to standard KUnit tests.
>
> Additionally disable usercopy_test_invalid() for systems with separate
> address spaces (or no MMU) since it's not sensible to test for address
> confusion there (e.g. m68k).
>
> Co-developed-by: Vitor Massaru Iha <[email protected]>
> Signed-off-by: Vitor Massaru Iha <[email protected]>
> Link: https://lore.kernel.org/r/[email protected]
> Tested-by: Ivan Orlov <[email protected]>
> Reviewed-by: David Gow <[email protected]>
> Signed-off-by: Kees Cook <[email protected]>
> ---
> MAINTAINERS | 1 +
> lib/Kconfig.debug | 21 +-
> lib/Makefile | 2 +-
> lib/{test_user_copy.c => usercopy_kunit.c} | 282 ++++++++++-----------
> 4 files changed, 151 insertions(+), 155 deletions(-)
> rename lib/{test_user_copy.c => usercopy_kunit.c} (46%)
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 8754ac2c259d..0cd171ec6010 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -11962,6 +11962,7 @@ F: arch/*/configs/hardening.config
> F: include/linux/overflow.h
> F: include/linux/randomize_kstack.h
> F: kernel/configs/hardening.config
> +F: lib/usercopy_kunit.c
> F: mm/usercopy.c
> K: \b(add|choose)_random_kstack_offset\b
> K: \b__check_(object_size|heap_object)\b
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 59b6765d86b8..561e346f5cb0 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -2505,18 +2505,6 @@ config TEST_VMALLOC
>
> If unsure, say N.
>
> -config TEST_USER_COPY
> - tristate "Test user/kernel boundary protections"
> - depends on m
> - help
> - This builds the "test_user_copy" module that runs sanity checks
> - on the copy_to/from_user infrastructure, making sure basic
> - user/kernel boundary testing is working. If it fails to load,
> - a regression has been detected in the user/kernel memory boundary
> - protections.
> -
> - If unsure, say N.
> -
> config TEST_BPF
> tristate "Test BPF filter functionality"
> depends on m && NET
> @@ -2814,6 +2802,15 @@ config SIPHASH_KUNIT_TEST
> This is intended to help people writing architecture-specific
> optimized versions. If unsure, say N.
>
> +config USERCOPY_KUNIT_TEST
> + tristate "KUnit Test for user/kernel boundary protections"
> + depends on KUNIT
> + default KUNIT_ALL_TESTS
> + help
> + This builds the "usercopy_kunit" module that runs sanity checks
> + on the copy_to/from_user infrastructure, making sure basic
> + user/kernel boundary testing is working.
> +
Please carry the following line forward as well to be complete assuming
it is relevant.
If unsure, say N.
thanks,
-- Shuah