Add basic success/failure checking of the user string functions which copy or find the length of userland strings. The following cases are checked: - strncpy_from_user() with legitimate user to kernel addresses, illegal all-kernel and reversed addresses, and legitimate all-kernel addresses. - strnlen_user()/strlen_user() with a legitimate user address, an illegal kernel address, and a legitimate kernel address. This caught a bug in the MIPS Enhanced Virtual Memory (EVA) implementation: test_user_copy: illegal strlen_user passed Due to strlen_user() accidentally always using normal kernel loads, and the EVA user/kernel address ranges overlapping. New tests: - legitimate strncpy_from_user - legitimate strnlen_user - legitimate strlen_user - illegal all-kernel strncpy_from_user - illegal reversed strncpy_from_user - illegal strnlen_user - illegal strlen_user - legitimate all-kernel strncpy_from_user - legitimate kernel strnlen_user - legitimate kernel strlen_user Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/test_user_copy.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/lib/test_user_copy.c b/lib/test_user_copy.c index 6cbdb0a15ca2..6d05ec5f6cfa 100644 --- a/lib/test_user_copy.c +++ b/lib/test_user_copy.c @@ -72,6 +72,12 @@ static int __init test_user_copy_init(void) "legitimate put_user failed"); ret |= test(clear_user(usermem, PAGE_SIZE) != 0, "legitimate clear_user passed"); + ret |= test(strncpy_from_user(kmem, usermem, PAGE_SIZE) < 0, + "legitimate strncpy_from_user failed"); + ret |= test(strnlen_user(usermem, PAGE_SIZE) == 0, + "legitimate strnlen_user failed"); + ret |= test(strlen_user(usermem) == 0, + "legitimate strlen_user failed"); ret |= test(!access_ok(VERIFY_READ, usermem, PAGE_SIZE * 2), "legitimate access_ok VERIFY_READ failed"); @@ -122,6 +128,16 @@ static int __init test_user_copy_init(void) "illegal put_user passed"); ret |= test(clear_user((char __user *)kmem, PAGE_SIZE) != PAGE_SIZE, "illegal kernel clear_user passed"); + ret |= test(strncpy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE), + PAGE_SIZE) >= 0, + "illegal all-kernel strncpy_from_user passed"); + ret |= test(strncpy_from_user(bad_usermem, (char __user *)kmem, + PAGE_SIZE) >= 0, + "illegal reversed strncpy_from_user passed"); + ret |= test(strnlen_user((char __user *)kmem, PAGE_SIZE) != 0, + "illegal strnlen_user passed"); + ret |= test(strlen_user((char __user *)kmem) != 0, + "illegal strlen_user passed"); /* * If unchecked user accesses (__*) on this architecture cannot access @@ -201,6 +217,13 @@ static int __init test_user_copy_init(void) "legitimate kernel put_user failed"); ret |= test(clear_user((char __user *)kmem, PAGE_SIZE) != 0, "legitimate kernel clear_user failed"); + ret |= test(strncpy_from_user(kmem, (char __user *)(kmem + PAGE_SIZE), + PAGE_SIZE) < 0, + "legitimate all-kernel strncpy_from_user failed"); + ret |= test(strnlen_user((char __user *)kmem, PAGE_SIZE) == 0, + "legitimate kernel strnlen_user failed"); + ret |= test(strlen_user((char __user *)kmem) == 0, + "legitimate kernel strlen_user failed"); ret |= test(!access_ok(VERIFY_READ, (char __user *)kmem, PAGE_SIZE * 2), "legitimate kernel access_ok VERIFY_READ failed"); -- 2.3.6
