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Commit f5f893c5 authored by Kees Cook's avatar Kees Cook
Browse files

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: default avatarKees Cook <keescook@chromium.org>
parent 4fbfeb8b

lib/test_user_copy.c

+24 −8
Original line number Diff line number Diff line
@@ -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");