v4.19.13 snapshot.
diff --git a/drivers/misc/lkdtm/usercopy.c b/drivers/misc/lkdtm/usercopy.c
new file mode 100644
index 0000000..9725aed
--- /dev/null
+++ b/drivers/misc/lkdtm/usercopy.c
@@ -0,0 +1,339 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This is for all the tests related to copy_to_user() and copy_from_user()
+ * hardening.
+ */
+#include "lkdtm.h"
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/sched/task_stack.h>
+#include <linux/mman.h>
+#include <linux/uaccess.h>
+#include <asm/cacheflush.h>
+
+/*
+ * Many of the tests here end up using const sizes, but those would
+ * normally be ignored by hardened usercopy, so force the compiler
+ * into choosing the non-const path to make sure we trigger the
+ * hardened usercopy checks by added "unconst" to all the const copies,
+ * and making sure "cache_size" isn't optimized into a const.
+ */
+static volatile size_t unconst = 0;
+static volatile size_t cache_size = 1024;
+static struct kmem_cache *whitelist_cache;
+
+static const unsigned char test_text[] = "This is a test.\n";
+
+/*
+ * 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,
+ unconst + 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,
+ unconst + 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,
+ unconst + 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,
+ unconst + sizeof(good_stack))) {
+ pr_warn("copy_from_user failed, but lacked Oops\n");
+ goto free_user;
+ }
+ }
+
+free_user:
+ vm_munmap(user_addr, PAGE_SIZE);
+}
+
+/*
+ * This checks for whole-object size validation with hardened usercopy,
+ * with or without usercopy whitelisting.
+ */
+static void do_usercopy_heap_size(bool to_user)
+{
+ unsigned long user_addr;
+ unsigned char *one, *two;
+ void __user *test_user_addr;
+ void *test_kern_addr;
+ size_t size = unconst + 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);
+
+ test_user_addr = (void __user *)(user_addr + 16);
+ test_kern_addr = one + 16;
+
+ if (to_user) {
+ pr_info("attempting good copy_to_user of correct size\n");
+ if (copy_to_user(test_user_addr, test_kern_addr, size / 2)) {
+ 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(test_user_addr, test_kern_addr, 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(test_kern_addr, test_user_addr, size / 2)) {
+ 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(test_kern_addr, test_user_addr, 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);
+}
+
+/*
+ * This checks for the specific whitelist window within an object. If this
+ * test passes, then do_usercopy_heap_size() tests will pass too.
+ */
+static void do_usercopy_heap_whitelist(bool to_user)
+{
+ unsigned long user_alloc;
+ unsigned char *buf = NULL;
+ unsigned char __user *user_addr;
+ size_t offset, size;
+
+ /* Make sure cache was prepared. */
+ if (!whitelist_cache) {
+ pr_warn("Failed to allocate kernel cache\n");
+ return;
+ }
+
+ /*
+ * Allocate a buffer with a whitelisted window in the buffer.
+ */
+ buf = kmem_cache_alloc(whitelist_cache, GFP_KERNEL);
+ if (!buf) {
+ pr_warn("Failed to allocate buffer from whitelist cache\n");
+ goto free_alloc;
+ }
+
+ /* Allocate user memory we'll poke at. */
+ user_alloc = vm_mmap(NULL, 0, PAGE_SIZE,
+ PROT_READ | PROT_WRITE | PROT_EXEC,
+ MAP_ANONYMOUS | MAP_PRIVATE, 0);
+ if (user_alloc >= TASK_SIZE) {
+ pr_warn("Failed to allocate user memory\n");
+ goto free_alloc;
+ }
+ user_addr = (void __user *)user_alloc;
+
+ memset(buf, 'B', cache_size);
+
+ /* Whitelisted window in buffer, from kmem_cache_create_usercopy. */
+ offset = (cache_size / 4) + unconst;
+ size = (cache_size / 16) + unconst;
+
+ if (to_user) {
+ pr_info("attempting good copy_to_user inside whitelist\n");
+ if (copy_to_user(user_addr, buf + offset, size)) {
+ pr_warn("copy_to_user failed unexpectedly?!\n");
+ goto free_user;
+ }
+
+ pr_info("attempting bad copy_to_user outside whitelist\n");
+ if (copy_to_user(user_addr, buf + offset - 1, size)) {
+ pr_warn("copy_to_user failed, but lacked Oops\n");
+ goto free_user;
+ }
+ } else {
+ pr_info("attempting good copy_from_user inside whitelist\n");
+ if (copy_from_user(buf + offset, user_addr, size)) {
+ pr_warn("copy_from_user failed unexpectedly?!\n");
+ goto free_user;
+ }
+
+ pr_info("attempting bad copy_from_user outside whitelist\n");
+ if (copy_from_user(buf + offset - 1, user_addr, size)) {
+ pr_warn("copy_from_user failed, but lacked Oops\n");
+ goto free_user;
+ }
+ }
+
+free_user:
+ vm_munmap(user_alloc, PAGE_SIZE);
+free_alloc:
+ if (buf)
+ kmem_cache_free(whitelist_cache, buf);
+}
+
+/* Callable tests. */
+void lkdtm_USERCOPY_HEAP_SIZE_TO(void)
+{
+ do_usercopy_heap_size(true);
+}
+
+void lkdtm_USERCOPY_HEAP_SIZE_FROM(void)
+{
+ do_usercopy_heap_size(false);
+}
+
+void lkdtm_USERCOPY_HEAP_WHITELIST_TO(void)
+{
+ do_usercopy_heap_whitelist(true);
+}
+
+void lkdtm_USERCOPY_HEAP_WHITELIST_FROM(void)
+{
+ do_usercopy_heap_whitelist(false);
+}
+
+void lkdtm_USERCOPY_STACK_FRAME_TO(void)
+{
+ do_usercopy_stack(true, true);
+}
+
+void lkdtm_USERCOPY_STACK_FRAME_FROM(void)
+{
+ do_usercopy_stack(false, true);
+}
+
+void lkdtm_USERCOPY_STACK_BEYOND(void)
+{
+ do_usercopy_stack(true, false);
+}
+
+void lkdtm_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,
+ unconst + 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,
+ unconst + PAGE_SIZE)) {
+ pr_warn("copy_to_user failed, but lacked Oops\n");
+ goto free_user;
+ }
+
+free_user:
+ vm_munmap(user_addr, PAGE_SIZE);
+}
+
+void __init lkdtm_usercopy_init(void)
+{
+ /* Prepare cache that lacks SLAB_USERCOPY flag. */
+ whitelist_cache =
+ kmem_cache_create_usercopy("lkdtm-usercopy", cache_size,
+ 0, 0,
+ cache_size / 4,
+ cache_size / 16,
+ NULL);
+}
+
+void __exit lkdtm_usercopy_exit(void)
+{
+ kmem_cache_destroy(whitelist_cache);
+}