lkdtm: split usercopy tests to separate file
This splits the USERCOPY_* tests into the new lkdtm_usercopy.c file to
help separate things better for readability.
Signed-off-by: Kees Cook <keescook@chromium.org>
diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
index 1454d58..7437692 100644
--- a/drivers/misc/lkdtm_core.c
+++ b/drivers/misc/lkdtm_core.c
@@ -193,10 +193,6 @@
static u8 data_area[EXEC_SIZE];
-static size_t cache_size = 1024;
-static struct kmem_cache *bad_cache;
-
-static const unsigned char test_text[] = "This is a test.\n";
static const unsigned long rodata = 0xAA55AA55;
static unsigned long ro_after_init __ro_after_init = 0x55AA5500;
@@ -403,255 +399,6 @@
func();
}
-/*
- * Instead of adding -Wno-return-local-addr, just pass the stack address
- * through a function to obfuscate it from the compiler.
- */
-static noinline unsigned char *trick_compiler(unsigned char *stack)
-{
- return stack + 0;
-}
-
-static noinline unsigned char *do_usercopy_stack_callee(int value)
-{
- unsigned char buf[32];
- int i;
-
- /* Exercise stack to avoid everything living in registers. */
- for (i = 0; i < sizeof(buf); i++) {
- buf[i] = value & 0xff;
- }
-
- return trick_compiler(buf);
-}
-
-static noinline void do_usercopy_stack(bool to_user, bool bad_frame)
-{
- unsigned long user_addr;
- unsigned char good_stack[32];
- unsigned char *bad_stack;
- int i;
-
- /* Exercise stack to avoid everything living in registers. */
- for (i = 0; i < sizeof(good_stack); i++)
- good_stack[i] = test_text[i % sizeof(test_text)];
-
- /* This is a pointer to outside our current stack frame. */
- if (bad_frame) {
- bad_stack = do_usercopy_stack_callee((uintptr_t)bad_stack);
- } else {
- /* Put start address just inside stack. */
- bad_stack = task_stack_page(current) + THREAD_SIZE;
- bad_stack -= sizeof(unsigned long);
- }
-
- user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
- PROT_READ | PROT_WRITE | PROT_EXEC,
- MAP_ANONYMOUS | MAP_PRIVATE, 0);
- if (user_addr >= TASK_SIZE) {
- pr_warn("Failed to allocate user memory\n");
- return;
- }
-
- if (to_user) {
- pr_info("attempting good copy_to_user of local stack\n");
- if (copy_to_user((void __user *)user_addr, good_stack,
- sizeof(good_stack))) {
- pr_warn("copy_to_user failed unexpectedly?!\n");
- goto free_user;
- }
-
- pr_info("attempting bad copy_to_user of distant stack\n");
- if (copy_to_user((void __user *)user_addr, bad_stack,
- sizeof(good_stack))) {
- pr_warn("copy_to_user failed, but lacked Oops\n");
- goto free_user;
- }
- } else {
- /*
- * There isn't a safe way to not be protected by usercopy
- * if we're going to write to another thread's stack.
- */
- if (!bad_frame)
- goto free_user;
-
- pr_info("attempting good copy_from_user of local stack\n");
- if (copy_from_user(good_stack, (void __user *)user_addr,
- sizeof(good_stack))) {
- pr_warn("copy_from_user failed unexpectedly?!\n");
- goto free_user;
- }
-
- pr_info("attempting bad copy_from_user of distant stack\n");
- if (copy_from_user(bad_stack, (void __user *)user_addr,
- sizeof(good_stack))) {
- pr_warn("copy_from_user failed, but lacked Oops\n");
- goto free_user;
- }
- }
-
-free_user:
- vm_munmap(user_addr, PAGE_SIZE);
-}
-
-static void do_usercopy_kernel(void)
-{
- unsigned long user_addr;
-
- user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
- PROT_READ | PROT_WRITE | PROT_EXEC,
- MAP_ANONYMOUS | MAP_PRIVATE, 0);
- if (user_addr >= TASK_SIZE) {
- pr_warn("Failed to allocate user memory\n");
- return;
- }
-
- pr_info("attempting good copy_to_user from kernel rodata\n");
- if (copy_to_user((void __user *)user_addr, test_text,
- sizeof(test_text))) {
- pr_warn("copy_to_user failed unexpectedly?!\n");
- goto free_user;
- }
-
- pr_info("attempting bad copy_to_user from kernel text\n");
- if (copy_to_user((void __user *)user_addr, vm_mmap, PAGE_SIZE)) {
- pr_warn("copy_to_user failed, but lacked Oops\n");
- goto free_user;
- }
-
-free_user:
- vm_munmap(user_addr, PAGE_SIZE);
-}
-
-static void do_usercopy_heap_size(bool to_user)
-{
- unsigned long user_addr;
- unsigned char *one, *two;
- size_t size = 1024;
-
- one = kmalloc(size, GFP_KERNEL);
- two = kmalloc(size, GFP_KERNEL);
- if (!one || !two) {
- pr_warn("Failed to allocate kernel memory\n");
- goto free_kernel;
- }
-
- user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
- PROT_READ | PROT_WRITE | PROT_EXEC,
- MAP_ANONYMOUS | MAP_PRIVATE, 0);
- if (user_addr >= TASK_SIZE) {
- pr_warn("Failed to allocate user memory\n");
- goto free_kernel;
- }
-
- memset(one, 'A', size);
- memset(two, 'B', size);
-
- if (to_user) {
- pr_info("attempting good copy_to_user of correct size\n");
- if (copy_to_user((void __user *)user_addr, one, size)) {
- pr_warn("copy_to_user failed unexpectedly?!\n");
- goto free_user;
- }
-
- pr_info("attempting bad copy_to_user of too large size\n");
- if (copy_to_user((void __user *)user_addr, one, 2 * size)) {
- pr_warn("copy_to_user failed, but lacked Oops\n");
- goto free_user;
- }
- } else {
- pr_info("attempting good copy_from_user of correct size\n");
- if (copy_from_user(one, (void __user *)user_addr, size)) {
- pr_warn("copy_from_user failed unexpectedly?!\n");
- goto free_user;
- }
-
- pr_info("attempting bad copy_from_user of too large size\n");
- if (copy_from_user(one, (void __user *)user_addr, 2 * size)) {
- pr_warn("copy_from_user failed, but lacked Oops\n");
- goto free_user;
- }
- }
-
-free_user:
- vm_munmap(user_addr, PAGE_SIZE);
-free_kernel:
- kfree(one);
- kfree(two);
-}
-
-static void do_usercopy_heap_flag(bool to_user)
-{
- unsigned long user_addr;
- unsigned char *good_buf = NULL;
- unsigned char *bad_buf = NULL;
-
- /* Make sure cache was prepared. */
- if (!bad_cache) {
- pr_warn("Failed to allocate kernel cache\n");
- return;
- }
-
- /*
- * Allocate one buffer from each cache (kmalloc will have the
- * SLAB_USERCOPY flag already, but "bad_cache" won't).
- */
- good_buf = kmalloc(cache_size, GFP_KERNEL);
- bad_buf = kmem_cache_alloc(bad_cache, GFP_KERNEL);
- if (!good_buf || !bad_buf) {
- pr_warn("Failed to allocate buffers from caches\n");
- goto free_alloc;
- }
-
- /* Allocate user memory we'll poke at. */
- user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
- PROT_READ | PROT_WRITE | PROT_EXEC,
- MAP_ANONYMOUS | MAP_PRIVATE, 0);
- if (user_addr >= TASK_SIZE) {
- pr_warn("Failed to allocate user memory\n");
- goto free_alloc;
- }
-
- memset(good_buf, 'A', cache_size);
- memset(bad_buf, 'B', cache_size);
-
- if (to_user) {
- pr_info("attempting good copy_to_user with SLAB_USERCOPY\n");
- if (copy_to_user((void __user *)user_addr, good_buf,
- cache_size)) {
- pr_warn("copy_to_user failed unexpectedly?!\n");
- goto free_user;
- }
-
- pr_info("attempting bad copy_to_user w/o SLAB_USERCOPY\n");
- if (copy_to_user((void __user *)user_addr, bad_buf,
- cache_size)) {
- pr_warn("copy_to_user failed, but lacked Oops\n");
- goto free_user;
- }
- } else {
- pr_info("attempting good copy_from_user with SLAB_USERCOPY\n");
- if (copy_from_user(good_buf, (void __user *)user_addr,
- cache_size)) {
- pr_warn("copy_from_user failed unexpectedly?!\n");
- goto free_user;
- }
-
- pr_info("attempting bad copy_from_user w/o SLAB_USERCOPY\n");
- if (copy_from_user(bad_buf, (void __user *)user_addr,
- cache_size)) {
- pr_warn("copy_from_user failed, but lacked Oops\n");
- goto free_user;
- }
- }
-
-free_user:
- vm_munmap(user_addr, PAGE_SIZE);
-free_alloc:
- if (bad_buf)
- kmem_cache_free(bad_cache, bad_buf);
- kfree(good_buf);
-}
static void lkdtm_do_action(enum ctype which)
{
@@ -964,28 +711,28 @@
return;
}
case CT_USERCOPY_HEAP_SIZE_TO:
- do_usercopy_heap_size(true);
+ lkdtm_USERCOPY_HEAP_SIZE_TO();
break;
case CT_USERCOPY_HEAP_SIZE_FROM:
- do_usercopy_heap_size(false);
+ lkdtm_USERCOPY_HEAP_SIZE_FROM();
break;
case CT_USERCOPY_HEAP_FLAG_TO:
- do_usercopy_heap_flag(true);
+ lkdtm_USERCOPY_HEAP_FLAG_TO();
break;
case CT_USERCOPY_HEAP_FLAG_FROM:
- do_usercopy_heap_flag(false);
+ lkdtm_USERCOPY_HEAP_FLAG_FROM();
break;
case CT_USERCOPY_STACK_FRAME_TO:
- do_usercopy_stack(true, true);
+ lkdtm_USERCOPY_STACK_FRAME_TO();
break;
case CT_USERCOPY_STACK_FRAME_FROM:
- do_usercopy_stack(false, true);
+ lkdtm_USERCOPY_STACK_FRAME_FROM();
break;
case CT_USERCOPY_STACK_BEYOND:
- do_usercopy_stack(true, false);
+ lkdtm_USERCOPY_STACK_BEYOND();
break;
case CT_USERCOPY_KERNEL:
- do_usercopy_kernel();
+ lkdtm_USERCOPY_KERNEL();
break;
case CT_NONE:
default:
@@ -1276,13 +1023,12 @@
int n_debugfs_entries = 1; /* Assume only the direct entry */
int i;
+ /* Handle test-specific initialization. */
+ lkdtm_usercopy_init();
+
/* Make sure we can write to __ro_after_init values during __init */
ro_after_init |= 0xAA;
- /* Prepare cache that lacks SLAB_USERCOPY flag. */
- bad_cache = kmem_cache_create("lkdtm-no-usercopy", cache_size, 0,
- 0, NULL);
-
/* Register debugfs interface */
lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
if (!lkdtm_debugfs_root) {
@@ -1334,7 +1080,8 @@
{
debugfs_remove_recursive(lkdtm_debugfs_root);
- kmem_cache_destroy(bad_cache);
+ /* Handle test-specific clean-up. */
+ lkdtm_usercopy_exit();
unregister_jprobe(&lkdtm);
pr_info("Crash point unregistered\n");