Merge tag 'usercopy-v4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull usercopy test updates from Kees Cook:
 "This improves the usercopy tests:

   - check zeroing on failed copy_from_user()/get_user() (caught bug on
     ARM)

   - adjust tests for SMAP/PAN (can't zero userspace memory on failure)"

* tag 'usercopy-v4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  usercopy: Add tests for all get_user() sizes
  usercopy: Adjust tests to deal with SMAP/PAN
  usercopy: add testcases to check zeroing on failure

lib/test_user_copy.c

@@ -25,6 +25,23 @@
 #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_AVR32)  &&		\
+			    !defined(CONFIG_BLACKFIN) &&	\
+			    !defined(CONFIG_M32R) &&		\
+			    !defined(CONFIG_M68K) &&		\
+			    !defined(CONFIG_MICROBLAZE) &&	\
+			    !defined(CONFIG_MN10300) &&		\
+			    !defined(CONFIG_NIOS2) &&		\
+			    !defined(CONFIG_PPC32) &&		\
+			    !defined(CONFIG_SUPERH))
+# define TEST_U64
+#endif
+
 #define test(condition, msg)		\
 ({					\
 	int cond = (condition);		\
@@ -40,7 +57,12 @@ static int __init test_user_copy_init(void)
 	char __user *usermem;
 	char *bad_usermem;
 	unsigned long user_addr;
-	unsigned long value = 0x5A;
+	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)
@@ -58,33 +80,100 @@ static int __init test_user_copy_init(void)
 	usermem = (char __user *)user_addr;
 	bad_usermem = (char *)user_addr;
 
-	/* Legitimate usage: none of these should fail. */
-	ret |= test(copy_from_user(kmem, usermem, PAGE_SIZE),
-		    "legitimate copy_from_user failed");
+	/*
+	 * 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");
-	ret |= test(get_user(value, (unsigned long __user *)usermem),
-		    "legitimate get_user failed");
-	ret |= test(put_user(value, (unsigned long __user *)usermem),
-		    "legitimate put_user failed");
-
-	/* Invalid usage: none of these should succeed. */
+	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
+
+	/*
+	 * 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");
-	ret |= test(!get_user(value, (unsigned long __user *)kmem),
-		    "illegal get_user passed");
-	ret |= test(!put_user(value, (unsigned long __user *)kmem),
-		    "illegal put_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);