Merge tag 'kernel-hardening-v5.19-rc1' of git://git.kernel.org/pub/sc…

…m/linux/kernel/git/kees/linux

Pull kernel hardening updates from Kees Cook:

 - usercopy hardening expanded to check other allocation types (Matthew
   Wilcox, Yuanzheng Song)

 - arm64 stackleak behavioral improvements (Mark Rutland)

 - arm64 CFI code gen improvement (Sami Tolvanen)

 - LoadPin LSM block dev API adjustment (Christoph Hellwig)

 - Clang randstruct support (Bill Wendling, Kees Cook)

* tag 'kernel-hardening-v5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (34 commits)
  loadpin: stop using bdevname
  mm: usercopy: move the virt_addr_valid() below the is_vmalloc_addr()
  gcc-plugins: randstruct: Remove cast exception handling
  af_unix: Silence randstruct GCC plugin warning
  niu: Silence randstruct warnings
  big_keys: Use struct for internal payload
  gcc-plugins: Change all version strings match kernel
  randomize_kstack: Improve docs on requirements/rationale
  lkdtm/stackleak: fix CONFIG_GCC_PLUGIN_STACKLEAK=n
  arm64: entry: use stackleak_erase_on_task_stack()
  stackleak: add on/off stack variants
  lkdtm/stackleak: check stack boundaries
  lkdtm/stackleak: prevent unexpected stack usage
  lkdtm/stackleak: rework boundary management
  lkdtm/stackleak: avoid spurious failure
  stackleak: rework poison scanning
  stackleak: rework stack high bound handling
  stackleak: clarify variable names
  stackleak: rework stack low bound handling
  stackleak: remove redundant check
  ...

Documentation/dontdiff

@@ -211,6 +211,7 @@ r200_reg_safe.h
 r300_reg_safe.h
 r420_reg_safe.h
 r600_reg_safe.h
+randstruct.seed
 randomize_layout_hash.h
 randomize_layout_seed.h
 recordmcount

Documentation/kbuild/reproducible-builds.rst

@@ -99,10 +99,10 @@ unreproducible parts can be treated as sources:
 Structure randomisation
 -----------------------
 
-If you enable ``CONFIG_GCC_PLUGIN_RANDSTRUCT``, you will need to
-pre-generate the random seed in
-``scripts/gcc-plugins/randomize_layout_seed.h`` so the same value
-is used in rebuilds.
+If you enable ``CONFIG_RANDSTRUCT``, you will need to pre-generate
+the random seed in ``scripts/basic/randstruct.seed`` so the same
+value is used by each build. See ``scripts/gen-randstruct-seed.sh``
+for details.
 
 Debug info conflicts
 --------------------

Makefile

@@ -1011,6 +1011,7 @@ include-$(CONFIG_KASAN)		+= scripts/Makefile.kasan
 include-$(CONFIG_KCSAN)		+= scripts/Makefile.kcsan
 include-$(CONFIG_UBSAN)		+= scripts/Makefile.ubsan
 include-$(CONFIG_KCOV)		+= scripts/Makefile.kcov
+include-$(CONFIG_RANDSTRUCT)	+= scripts/Makefile.randstruct
 include-$(CONFIG_GCC_PLUGINS)	+= scripts/Makefile.gcc-plugins
 
 include $(addprefix $(srctree)/, $(include-y))

arch/Kconfig

@@ -732,10 +732,7 @@ config ARCH_SUPPORTS_CFI_CLANG
 config CFI_CLANG
 	bool "Use Clang's Control Flow Integrity (CFI)"
 	depends on LTO_CLANG && ARCH_SUPPORTS_CFI_CLANG
-	# Clang >= 12:
-	# - https://bugs.llvm.org/show_bug.cgi?id=46258
-	# - https://bugs.llvm.org/show_bug.cgi?id=47479
-	depends on CLANG_VERSION >= 120000
+	depends on CLANG_VERSION >= 140000
 	select KALLSYMS
 	help
 	  This option enables Clang’s forward-edge Control Flow Integrity

arch/arm/vdso/Makefile

@@ -28,7 +28,7 @@ CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
 CFLAGS_REMOVE_vdso.o = -pg
 
 # Force -O2 to avoid libgcc dependencies
-CFLAGS_REMOVE_vgettimeofday.o = -pg -Os $(GCC_PLUGINS_CFLAGS)
+CFLAGS_REMOVE_vgettimeofday.o = -pg -Os $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS)
 ifeq ($(c-gettimeofday-y),)
 CFLAGS_vgettimeofday.o = -O2
 else

arch/arm64/include/asm/compiler.h

@@ -23,20 +23,4 @@
 #define __builtin_return_address(val)					\
 	(void *)(ptrauth_clear_pac((unsigned long)__builtin_return_address(val)))
 
-#ifdef CONFIG_CFI_CLANG
-/*
- * With CONFIG_CFI_CLANG, the compiler replaces function address
- * references with the address of the function's CFI jump table
- * entry. The function_nocfi macro always returns the address of the
- * actual function instead.
- */
-#define function_nocfi(x) ({						\
-	void *addr;							\
-	asm("adrp %0, " __stringify(x) "\n\t"				\
-	    "add  %0, %0, :lo12:" __stringify(x)			\
-	    : "=r" (addr));						\
-	addr;								\
-})
-#endif
-
 #endif /* __ASM_COMPILER_H */

arch/arm64/include/asm/processor.h

@@ -405,12 +405,10 @@ long get_tagged_addr_ctrl(struct task_struct *task);
  * of header definitions for the use of task_stack_page.
  */
 
-#define current_top_of_stack()								\
-({											\
-	struct stack_info _info;							\
-	BUG_ON(!on_accessible_stack(current, current_stack_pointer, 1, &_info));	\
-	_info.high;									\
-})
+/*
+ * The top of the current task's task stack
+ */
+#define current_top_of_stack()	((unsigned long)current->stack + THREAD_SIZE)
 #define on_thread_stack()	(on_task_stack(current, current_stack_pointer, 1, NULL))
 
 #endif /* __ASSEMBLY__ */

arch/arm64/kernel/entry.S

@@ -596,7 +596,7 @@ SYM_CODE_START_LOCAL(ret_to_user)
 	ldr	x19, [tsk, #TSK_TI_FLAGS]	// re-check for single-step
 	enable_step_tsk x19, x2
 #ifdef CONFIG_GCC_PLUGIN_STACKLEAK
-	bl	stackleak_erase
+	bl	stackleak_erase_on_task_stack
 #endif
 	kernel_exit 0
 SYM_CODE_END(ret_to_user)

arch/arm64/kernel/vdso/Makefile

@@ -32,7 +32,8 @@ ccflags-y += -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO
 # -Wmissing-prototypes and -Wmissing-declarations are removed from
 # the CFLAGS of vgettimeofday.c to make possible to build the
 # kernel with CONFIG_WERROR enabled.
-CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) $(GCC_PLUGINS_CFLAGS) \
+CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) \
+				$(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) \
 				$(CC_FLAGS_LTO) -Wmissing-prototypes -Wmissing-declarations
 KASAN_SANITIZE			:= n
 KCSAN_SANITIZE			:= n

arch/riscv/Kconfig

@@ -468,7 +468,7 @@ config CC_HAVE_STACKPROTECTOR_TLS
 
 config STACKPROTECTOR_PER_TASK
 	def_bool y
-	depends on !GCC_PLUGIN_RANDSTRUCT
+	depends on !RANDSTRUCT
 	depends on STACKPROTECTOR && CC_HAVE_STACKPROTECTOR_TLS
 
 config PHYS_RAM_BASE_FIXED

arch/sparc/vdso/Makefile

@@ -58,7 +58,7 @@ CFL := $(PROFILING) -mcmodel=medlow -fPIC -O2 -fasynchronous-unwind-tables -m64
 
 SPARC_REG_CFLAGS = -ffixed-g4 -ffixed-g5 -fcall-used-g5 -fcall-used-g7
 
-$(vobjs): KBUILD_CFLAGS := $(filter-out $(GCC_PLUGINS_CFLAGS) $(SPARC_REG_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)
+$(vobjs): KBUILD_CFLAGS := $(filter-out $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(SPARC_REG_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)
 
 #
 # vDSO code runs in userspace and -pg doesn't help with profiling anyway.
@@ -88,6 +88,7 @@ $(obj)/vdso32.so.dbg: asflags-$(CONFIG_SPARC64) += -m32
 KBUILD_CFLAGS_32 := $(filter-out -m64,$(KBUILD_CFLAGS))
 KBUILD_CFLAGS_32 := $(filter-out -mcmodel=medlow,$(KBUILD_CFLAGS_32))
 KBUILD_CFLAGS_32 := $(filter-out -fno-pic,$(KBUILD_CFLAGS_32))
+KBUILD_CFLAGS_32 := $(filter-out $(RANDSTRUCT_CFLAGS),$(KBUILD_CFLAGS_32))
 KBUILD_CFLAGS_32 := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS_32))
 KBUILD_CFLAGS_32 := $(filter-out $(SPARC_REG_CFLAGS),$(KBUILD_CFLAGS_32))
 KBUILD_CFLAGS_32 += -m32 -msoft-float -fpic

arch/x86/entry/vdso/Makefile

@@ -91,7 +91,7 @@ ifneq ($(RETPOLINE_VDSO_CFLAGS),)
 endif
 endif
 
-$(vobjs): KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO) $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)
+$(vobjs): KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO) $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)
 
 #
 # vDSO code runs in userspace and -pg doesn't help with profiling anyway.
@@ -148,6 +148,7 @@ KBUILD_CFLAGS_32 := $(filter-out -m64,$(KBUILD_CFLAGS))
 KBUILD_CFLAGS_32 := $(filter-out -mcmodel=kernel,$(KBUILD_CFLAGS_32))
 KBUILD_CFLAGS_32 := $(filter-out -fno-pic,$(KBUILD_CFLAGS_32))
 KBUILD_CFLAGS_32 := $(filter-out -mfentry,$(KBUILD_CFLAGS_32))
+KBUILD_CFLAGS_32 := $(filter-out $(RANDSTRUCT_CFLAGS),$(KBUILD_CFLAGS_32))
 KBUILD_CFLAGS_32 := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS_32))
 KBUILD_CFLAGS_32 := $(filter-out $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS_32))
 KBUILD_CFLAGS_32 := $(filter-out $(CC_FLAGS_LTO),$(KBUILD_CFLAGS_32))

arch/x86/include/asm/highmem.h

@@ -26,6 +26,7 @@
 #include <asm/tlbflush.h>
 #include <asm/paravirt.h>
 #include <asm/fixmap.h>
+#include <asm/pgtable_areas.h>
 
 /* declarations for highmem.c */
 extern unsigned long highstart_pfn, highend_pfn;

arch/x86/mm/pti.c

@@ -540,7 +540,7 @@ static inline bool pti_kernel_image_global_ok(void)
 	 * cases where RANDSTRUCT is in use to help keep the layout a
 	 * secret.
 	 */
-	if (IS_ENABLED(CONFIG_GCC_PLUGIN_RANDSTRUCT))
+	if (IS_ENABLED(CONFIG_RANDSTRUCT))
 		return false;
 
 	return true;

drivers/misc/lkdtm/stackleak.c

@@ -11,72 +11,125 @@
 #include "lkdtm.h"
 #include <linux/stackleak.h>
 
-void lkdtm_STACKLEAK_ERASING(void)
+#if defined(CONFIG_GCC_PLUGIN_STACKLEAK)
+/*
+ * Check that stackleak tracks the lowest stack pointer and erases the stack
+ * below this as expected.
+ *
+ * To prevent the lowest stack pointer changing during the test, IRQs are
+ * masked and instrumentation of this function is disabled. We assume that the
+ * compiler will create a fixed-size stack frame for this function.
+ *
+ * Any non-inlined function may make further use of the stack, altering the
+ * lowest stack pointer and/or clobbering poison values. To avoid spurious
+ * failures we must avoid printing until the end of the test or have already
+ * encountered a failure condition.
+ */
+static void noinstr check_stackleak_irqoff(void)
 {
-	unsigned long *sp, left, found, i;
-	const unsigned long check_depth =
-			STACKLEAK_SEARCH_DEPTH / sizeof(unsigned long);
+	const unsigned long task_stack_base = (unsigned long)task_stack_page(current);
+	const unsigned long task_stack_low = stackleak_task_low_bound(current);
+	const unsigned long task_stack_high = stackleak_task_high_bound(current);
+	const unsigned long current_sp = current_stack_pointer;
+	const unsigned long lowest_sp = current->lowest_stack;
+	unsigned long untracked_high;
+	unsigned long poison_high, poison_low;
 	bool test_failed = false;
 
 	/*
-	 * For the details about the alignment of the poison values, see
-	 * the comment in stackleak_track_stack().
+	 * Check that the current and lowest recorded stack pointer values fall
+	 * within the expected task stack boundaries. These tests should never
+	 * fail unless the boundaries are incorrect or we're clobbering the
+	 * STACK_END_MAGIC, and in either casee something is seriously wrong.
 	 */
-	sp = PTR_ALIGN(&i, sizeof(unsigned long));
-
-	left = ((unsigned long)sp & (THREAD_SIZE - 1)) / sizeof(unsigned long);
-	sp--;
+	if (current_sp < task_stack_low || current_sp >= task_stack_high) {
+		pr_err("FAIL: current_stack_pointer (0x%lx) outside of task stack bounds [0x%lx..0x%lx]\n",
+		       current_sp, task_stack_low, task_stack_high - 1);
+		test_failed = true;
+		goto out;
+	}
+	if (lowest_sp < task_stack_low || lowest_sp >= task_stack_high) {
+		pr_err("FAIL: current->lowest_stack (0x%lx) outside of task stack bounds [0x%lx..0x%lx]\n",
+		       lowest_sp, task_stack_low, task_stack_high - 1);
+		test_failed = true;
+		goto out;
+	}
 
 	/*
-	 * One 'long int' at the bottom of the thread stack is reserved
-	 * and not poisoned.
+	 * Depending on what has run prior to this test, the lowest recorded
+	 * stack pointer could be above or below the current stack pointer.
+	 * Start from the lowest of the two.
+	 *
+	 * Poison values are naturally-aligned unsigned longs. As the current
+	 * stack pointer might not be sufficiently aligned, we must align
+	 * downwards to find the lowest known stack pointer value. This is the
+	 * high boundary for a portion of the stack which may have been used
+	 * without being tracked, and has to be scanned for poison.
 	 */
-	if (left > 1) {
-		left--;
-	} else {
-		pr_err("FAIL: not enough stack space for the test\n");
-		test_failed = true;
-		goto end;
-	}
+	untracked_high = min(current_sp, lowest_sp);
+	untracked_high = ALIGN_DOWN(untracked_high, sizeof(unsigned long));
 
-	pr_info("checking unused part of the thread stack (%lu bytes)...\n",
-					left * sizeof(unsigned long));
+	/*
+	 * Find the top of the poison in the same way as the erasing code.
+	 */
+	poison_high = stackleak_find_top_of_poison(task_stack_low, untracked_high);
 
 	/*
-	 * Search for 'check_depth' poison values in a row (just like
-	 * stackleak_erase() does).
+	 * Check whether the poisoned portion of the stack (if any) consists
+	 * entirely of poison. This verifies the entries that
+	 * stackleak_find_top_of_poison() should have checked.
 	 */
-	for (i = 0, found = 0; i < left && found <= check_depth; i++) {
-		if (*(sp - i) == STACKLEAK_POISON)
-			found++;
-		else
-			found = 0;
-	}
+	poison_low = poison_high;
+	while (poison_low > task_stack_low) {
+		poison_low -= sizeof(unsigned long);
+
+		if (*(unsigned long *)poison_low == STACKLEAK_POISON)
+			continue;
 
-	if (found <= check_depth) {
-		pr_err("FAIL: the erased part is not found (checked %lu bytes)\n",
-						i * sizeof(unsigned long));
+		pr_err("FAIL: non-poison value %lu bytes below poison boundary: 0x%lx\n",
+		       poison_high - poison_low, *(unsigned long *)poison_low);
 		test_failed = true;
-		goto end;
 	}
 
-	pr_info("the erased part begins after %lu not poisoned bytes\n",
-				(i - found) * sizeof(unsigned long));
-
-	/* The rest of thread stack should be erased */
-	for (; i < left; i++) {
-		if (*(sp - i) != STACKLEAK_POISON) {
-			pr_err("FAIL: bad value number %lu in the erased part: 0x%lx\n",
-								i, *(sp - i));
-			test_failed = true;
-		}
-	}
+	pr_info("stackleak stack usage:\n"
+		"  high offset: %lu bytes\n"
+		"  current:     %lu bytes\n"
+		"  lowest:      %lu bytes\n"
+		"  tracked:     %lu bytes\n"
+		"  untracked:   %lu bytes\n"
+		"  poisoned:    %lu bytes\n"
+		"  low offset:  %lu bytes\n",
+		task_stack_base + THREAD_SIZE - task_stack_high,
+		task_stack_high - current_sp,
+		task_stack_high - lowest_sp,
+		task_stack_high - untracked_high,
+		untracked_high - poison_high,
+		poison_high - task_stack_low,
+		task_stack_low - task_stack_base);
 
-end:
+out:
 	if (test_failed) {
 		pr_err("FAIL: the thread stack is NOT properly erased!\n");
-		pr_expected_config(CONFIG_GCC_PLUGIN_STACKLEAK);
 	} else {
 		pr_info("OK: the rest of the thread stack is properly erased\n");
 	}
 }
+
+void lkdtm_STACKLEAK_ERASING(void)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	check_stackleak_irqoff();
+	local_irq_restore(flags);
+}
+#else /* defined(CONFIG_GCC_PLUGIN_STACKLEAK) */
+void lkdtm_STACKLEAK_ERASING(void)
+{
+	if (IS_ENABLED(CONFIG_HAVE_ARCH_STACKLEAK)) {
+		pr_err("XFAIL: stackleak is not enabled (CONFIG_GCC_PLUGIN_STACKLEAK=n)\n");
+	} else {
+		pr_err("XFAIL: stackleak is not supported on this arch (HAVE_ARCH_STACKLEAK=n)\n");
+	}
+}
+#endif /* defined(CONFIG_GCC_PLUGIN_STACKLEAK) */