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-rw-r--r--lib/test_user_copy.c331
1 files changed, 331 insertions, 0 deletions
diff --git a/lib/test_user_copy.c b/lib/test_user_copy.c
new file mode 100644
index 000000000..5ff04d8fe
--- /dev/null
+++ b/lib/test_user_copy.c
@@ -0,0 +1,331 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Kernel module for testing copy_to/from_user infrastructure.
+ *
+ * Copyright 2013 Google Inc. All Rights Reserved
+ *
+ * Authors:
+ * Kees Cook <keescook@chromium.org>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/mman.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/vmalloc.h>
+
+/*
+ * Several 32-bit architectures support 64-bit {get,put}_user() calls.
+ * As there doesn't appear to be anything that can safely determine
+ * their capability at compile-time, we just have to opt-out certain archs.
+ */
+#if BITS_PER_LONG == 64 || (!(defined(CONFIG_ARM) && !defined(MMU)) && \
+ !defined(CONFIG_M68K) && \
+ !defined(CONFIG_MICROBLAZE) && \
+ !defined(CONFIG_NIOS2) && \
+ !defined(CONFIG_PPC32) && \
+ !defined(CONFIG_SUPERH))
+# define TEST_U64
+#endif
+
+#define test(condition, msg, ...) \
+({ \
+ int cond = (condition); \
+ if (cond) \
+ pr_warn("[%d] " msg "\n", __LINE__, ##__VA_ARGS__); \
+ cond; \
+})
+
+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)
+{
+ int ret = 0;
+ size_t start, end, i, zero_start, zero_end;
+
+ if (test(size < 2 * PAGE_SIZE, "buffer too small"))
+ return -EINVAL;
+
+ /*
+ * We want to cross a page boundary to exercise the code more
+ * effectively. We also don't want to make the size we scan too large,
+ * otherwise the test can take a long time and cause soft lockups. So
+ * scan a 1024 byte region across the page boundary.
+ */
+ size = 1024;
+ start = PAGE_SIZE - (size / 2);
+
+ kmem += start;
+ umem += start;
+
+ zero_start = size / 4;
+ zero_end = size - zero_start;
+
+ /*
+ * We conduct a series of check_nonzero_user() tests on a block of
+ * memory with the following byte-pattern (trying every possible
+ * [start,end] pair):
+ *
+ * [ 00 ff 00 ff ... 00 00 00 00 ... ff 00 ff 00 ]
+ *
+ * And we verify that check_nonzero_user() acts identically to
+ * memchr_inv().
+ */
+
+ memset(kmem, 0x0, size);
+ for (i = 1; i < zero_start; i += 2)
+ kmem[i] = 0xff;
+ for (i = zero_end; i < size; i += 2)
+ kmem[i] = 0xff;
+
+ ret |= test(copy_to_user(umem, kmem, size),
+ "legitimate copy_to_user failed");
+
+ for (start = 0; start <= size; start++) {
+ for (end = start; end <= size; end++) {
+ size_t len = end - start;
+ 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);
+ }
+ }
+
+ return ret;
+}
+
+static int test_copy_struct_from_user(char *kmem, char __user *umem,
+ size_t size)
+{
+ int ret = 0;
+ char *umem_src = NULL, *expected = NULL;
+ size_t ksize, usize;
+
+ umem_src = kmalloc(size, GFP_KERNEL);
+ ret = test(umem_src == NULL, "kmalloc failed");
+ if (ret)
+ goto out_free;
+
+ expected = kmalloc(size, GFP_KERNEL);
+ ret = test(expected == NULL, "kmalloc failed");
+ if (ret)
+ goto out_free;
+
+ /* Fill umem with a fixed byte pattern. */
+ memset(umem_src, 0x3e, size);
+ ret |= test(copy_to_user(umem, umem_src, size),
+ "legitimate copy_to_user failed");
+
+ /* Check basic case -- (usize == ksize). */
+ ksize = size;
+ usize = size;
+
+ memcpy(expected, umem_src, ksize);
+
+ memset(kmem, 0x0, size);
+ ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
+ "copy_struct_from_user(usize == ksize) failed");
+ ret |= test(memcmp(kmem, expected, ksize),
+ "copy_struct_from_user(usize == ksize) gives unexpected copy");
+
+ /* Old userspace case -- (usize < ksize). */
+ ksize = size;
+ usize = size / 2;
+
+ memcpy(expected, umem_src, usize);
+ memset(expected + usize, 0x0, ksize - usize);
+
+ memset(kmem, 0x0, size);
+ ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
+ "copy_struct_from_user(usize < ksize) failed");
+ ret |= test(memcmp(kmem, expected, ksize),
+ "copy_struct_from_user(usize < ksize) gives unexpected copy");
+
+ /* New userspace (-E2BIG) case -- (usize > ksize). */
+ ksize = size / 2;
+ usize = size;
+
+ memset(kmem, 0x0, size);
+ ret |= 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). */
+ ksize = size / 2;
+ usize = size;
+
+ memcpy(expected, umem_src, ksize);
+ ret |= test(clear_user(umem + ksize, usize - ksize),
+ "legitimate clear_user failed");
+
+ memset(kmem, 0x0, size);
+ ret |= test(copy_struct_from_user(kmem, ksize, umem, usize),
+ "copy_struct_from_user(usize > ksize) failed");
+ ret |= test(memcmp(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)
+{
+ 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
+
+ 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");
+ 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); \
+ } \
+ } while (0)
+
+ test_legit(u8, 0x5a);
+ test_legit(u16, 0x5a5b);
+ test_legit(u32, 0x5a5b5c5d);
+#ifdef TEST_U64
+ 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.
+ */
+
+ /* 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),
+ "illegal all-kernel copy_from_user passed");
+
+ /* Destination half of buffer should have been zeroed. */
+ ret |= test(memcmp(kmem + PAGE_SIZE, kmem, PAGE_SIZE),
+ "zeroing failure for illegal all-kernel copy_from_user");
+
+#if 0
+ /*
+ * When running with SMAP/PAN/etc, this will Oops the kernel
+ * due to the zeroing of userspace memory on failure. This needs
+ * 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),
+ "illegal reversed copy_from_user passed");
+#endif
+ ret |= test(!copy_to_user((char __user *)kmem, kmem + PAGE_SIZE,
+ PAGE_SIZE),
+ "illegal all-kernel copy_to_user passed");
+ ret |= test(!copy_to_user((char __user *)kmem, bad_usermem,
+ PAGE_SIZE),
+ "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"); \
+ } while (0)
+
+ test_illegal(u8, 0x5a);
+ test_illegal(u16, 0x5a5b);
+ test_illegal(u32, 0x5a5b5c5d);
+#ifdef TEST_U64
+ test_illegal(u64, 0x5a5b5c5d6a6b6c6d);
+#endif
+#undef test_illegal
+
+ vm_munmap(user_addr, PAGE_SIZE * 2);
+ kfree(kmem);
+
+ if (ret == 0) {
+ pr_info("tests passed.\n");
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
+module_init(test_user_copy_init);
+
+static void __exit test_user_copy_exit(void)
+{
+ pr_info("unloaded.\n");
+}
+
+module_exit(test_user_copy_exit);
+
+MODULE_AUTHOR("Kees Cook <keescook@chromium.org>");
+MODULE_LICENSE("GPL");
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-01 01:02:00 +0000