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authorKees Cook <keescook@chromium.org>2017-02-13 11:25:26 -0800
committerKees Cook <keescook@chromium.org>2017-02-16 16:34:59 -0800
commitf5f893c57e37ca730808cb2eee3820abd05e7507 (patch)
tree64e6e91e1728dc333ea1a267c31f8076d95bb0ef
parent4fbfeb8bd684d564bddeff1e3723d3d9f99aa5de (diff)
usercopy: Adjust tests to deal with SMAP/PAN
Under SMAP/PAN/etc, we cannot write directly to userspace memory, so this rearranges the test bytes to get written through copy_to_user(). Additionally drops the bad copy_from_user() test that would trigger a memcpy() against userspace on failure. Signed-off-by: Kees Cook <keescook@chromium.org>
-rw-r--r--lib/test_user_copy.c32
1 files changed, 24 insertions, 8 deletions
diff --git a/lib/test_user_copy.c b/lib/test_user_copy.c
index 0f86c67d87db..73ff7a628e3a 100644
--- a/lib/test_user_copy.c
+++ b/lib/test_user_copy.c
@@ -58,7 +58,9 @@ 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. */
+ /*
+ * Legitimate usage: none of these copies should fail.
+ */
ret |= test(copy_from_user(kmem, usermem, PAGE_SIZE),
"legitimate copy_from_user failed");
ret |= test(copy_to_user(usermem, kmem, PAGE_SIZE),
@@ -68,31 +70,45 @@ static int __init test_user_copy_init(void)
ret |= test(put_user(value, (unsigned long __user *)usermem),
"legitimate put_user failed");
- /* Invalid usage: none of these should succeed. */
+ /*
+ * 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");
- memset(bad_usermem, 0x5A, PAGE_SIZE);
+
+#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");
- ret |= test(memcmp(kmem + PAGE_SIZE, bad_usermem, PAGE_SIZE),
- "zeroing failure for illegal reversed copy_from_user");
+#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");
- memset(kmem, 0x5a, PAGE_SIZE);
+
+ value = 0x5a;
ret |= test(!get_user(value, (unsigned long __user *)kmem),
"illegal get_user passed");
- ret |= test(memcmp(kmem + PAGE_SIZE, kmem, sizeof(value)),
- "zeroing failure for illegal get_user");
+ ret |= test(value != 0, "zeroing failure for illegal get_user");
ret |= test(!put_user(value, (unsigned long __user *)kmem),
"illegal put_user passed");