usercopy: Add tests for all get_user() sizes

The existing test was only exercising native unsigned long size
get_user(). For completeness, we should check all sizes. But we
must skip some 32-bit architectures that don't implement a 64-bit
get_user().

These new tests actually uncovered a bug in ARM's 64-bit get_user()
zeroing.

Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/lib/test_user_copy.c b/lib/test_user_copy.c
index 73ff7a628e3a14c88c4b861e78225891d45cd571..6f335a3d4ae2e192e2afe98111762a45ce995959 100644 (file)
--- a/lib/test_user_copy.c
+++ b/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)
@@ -61,14 +83,39 @@ static int __init test_user_copy_init(void)
        /*
         * Legitimate usage: none of these copies should fail.
         */
-       ret |= test(copy_from_user(kmem, usermem, PAGE_SIZE),
-                   "legitimate copy_from_user failed");
+       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");
+       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.
@@ -105,12 +152,28 @@ static int __init test_user_copy_init(void)
                                  PAGE_SIZE),
                    "illegal reversed copy_to_user passed");
 
-       value = 0x5a;
-       ret |= test(!get_user(value, (unsigned long __user *)kmem),
-                   "illegal get_user passed");
-       ret |= test(value != 0, "zeroing failure for illegal get_user");
-       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);