diff options
author | Kees Cook <keescook@chromium.org> | 2017-02-13 11:25:26 -0800 |
---|---|---|
committer | Kees Cook <keescook@chromium.org> | 2017-02-16 16:34:59 -0800 |
commit | f5f893c57e37ca730808cb2eee3820abd05e7507 (patch) | |
tree | 64e6e91e1728dc333ea1a267c31f8076d95bb0ef | |
parent | 4fbfeb8bd684d564bddeff1e3723d3d9f99aa5de (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.c | 32 |
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"); |