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

1 files changed, 103 insertions, 14 deletions

diff --git a/lib/test_user_copy.c b/lib/test_user_copy.c
index 0ecef3e4690e..6f335a3d4ae2 100644
--- 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)
@@ -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);