From b8e147973eca7e07fa0845350d77c9970263fcd7 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 9 Apr 2025 09:04:10 -0700 Subject: gcc-plugins: Remove ARM_SSP_PER_TASK plugin As part of trying to remove GCC plugins from Linux, drop the ARM_SSP_PER_TASK plugin. The feature is available upstream since GCC 12, so anyone needing newer kernels with per-task ssp can update their compiler[1]. Suggested-by: Arnd Bergmann Link: https://lore.kernel.org/all/08393aa3-05a3-4e3f-8004-f374a3ec4b7e@app.fastmail.com/ [1] Acked-by: Arnd Bergmann Acked-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20250409160409.work.168-kees@kernel.org Signed-off-by: Kees Cook --- scripts/Makefile.gcc-plugins | 6 -- scripts/gcc-plugins/Kconfig | 4 - scripts/gcc-plugins/arm_ssp_per_task_plugin.c | 107 -------------------------- 3 files changed, 117 deletions(-) delete mode 100644 scripts/gcc-plugins/arm_ssp_per_task_plugin.c (limited to 'scripts') diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins index e4deaf5fa571..5b8a8378ca8a 100644 --- a/scripts/Makefile.gcc-plugins +++ b/scripts/Makefile.gcc-plugins @@ -36,12 +36,6 @@ ifdef CONFIG_GCC_PLUGIN_STACKLEAK endif export DISABLE_STACKLEAK_PLUGIN -gcc-plugin-$(CONFIG_GCC_PLUGIN_ARM_SSP_PER_TASK) += arm_ssp_per_task_plugin.so -ifdef CONFIG_GCC_PLUGIN_ARM_SSP_PER_TASK - DISABLE_ARM_SSP_PER_TASK_PLUGIN += -fplugin-arg-arm_ssp_per_task_plugin-disable -endif -export DISABLE_ARM_SSP_PER_TASK_PLUGIN - # All the plugin CFLAGS are collected here in case a build target needs to # filter them out of the KBUILD_CFLAGS. GCC_PLUGINS_CFLAGS := $(strip $(addprefix -fplugin=$(objtree)/scripts/gcc-plugins/, $(gcc-plugin-y)) $(gcc-plugin-cflags-y)) diff --git a/scripts/gcc-plugins/Kconfig b/scripts/gcc-plugins/Kconfig index e383cda05367..231f4a20d617 100644 --- a/scripts/gcc-plugins/Kconfig +++ b/scripts/gcc-plugins/Kconfig @@ -46,8 +46,4 @@ config GCC_PLUGIN_LATENT_ENTROPY * https://grsecurity.net/ * https://pax.grsecurity.net/ -config GCC_PLUGIN_ARM_SSP_PER_TASK - bool - depends on GCC_PLUGINS && ARM - endif diff --git a/scripts/gcc-plugins/arm_ssp_per_task_plugin.c b/scripts/gcc-plugins/arm_ssp_per_task_plugin.c deleted file mode 100644 index 7328d037f975..000000000000 --- a/scripts/gcc-plugins/arm_ssp_per_task_plugin.c +++ /dev/null @@ -1,107 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 - -#include "gcc-common.h" - -__visible int plugin_is_GPL_compatible; - -static unsigned int canary_offset; - -static unsigned int arm_pertask_ssp_rtl_execute(void) -{ - rtx_insn *insn; - - for (insn = get_insns(); insn; insn = NEXT_INSN(insn)) { - const char *sym; - rtx body; - rtx current; - - /* - * Find a SET insn involving a SYMBOL_REF to __stack_chk_guard - */ - if (!INSN_P(insn)) - continue; - body = PATTERN(insn); - if (GET_CODE(body) != SET || - GET_CODE(SET_SRC(body)) != SYMBOL_REF) - continue; - sym = XSTR(SET_SRC(body), 0); - if (strcmp(sym, "__stack_chk_guard")) - continue; - - /* - * Replace the source of the SET insn with an expression that - * produces the address of the current task's stack canary value - */ - current = gen_reg_rtx(Pmode); - - emit_insn_before(gen_load_tp_hard(current), insn); - - SET_SRC(body) = gen_rtx_PLUS(Pmode, current, - GEN_INT(canary_offset)); - } - return 0; -} - -#define PASS_NAME arm_pertask_ssp_rtl - -#define NO_GATE -#include "gcc-generate-rtl-pass.h" - -#if BUILDING_GCC_VERSION >= 9000 -static bool no(void) -{ - return false; -} - -static void arm_pertask_ssp_start_unit(void *gcc_data, void *user_data) -{ - targetm.have_stack_protect_combined_set = no; - targetm.have_stack_protect_combined_test = no; -} -#endif - -__visible int plugin_init(struct plugin_name_args *plugin_info, - struct plugin_gcc_version *version) -{ - const char * const plugin_name = plugin_info->base_name; - const int argc = plugin_info->argc; - const struct plugin_argument *argv = plugin_info->argv; - int i; - - if (!plugin_default_version_check(version, &gcc_version)) { - error(G_("incompatible gcc/plugin versions")); - return 1; - } - - for (i = 0; i < argc; ++i) { - if (!strcmp(argv[i].key, "disable")) - return 0; - - /* all remaining options require a value */ - if (!argv[i].value) { - error(G_("no value supplied for option '-fplugin-arg-%s-%s'"), - plugin_name, argv[i].key); - return 1; - } - - if (!strcmp(argv[i].key, "offset")) { - canary_offset = atoi(argv[i].value); - continue; - } - error(G_("unknown option '-fplugin-arg-%s-%s'"), - plugin_name, argv[i].key); - return 1; - } - - PASS_INFO(arm_pertask_ssp_rtl, "expand", 1, PASS_POS_INSERT_AFTER); - - register_callback(plugin_info->base_name, PLUGIN_PASS_MANAGER_SETUP, - NULL, &arm_pertask_ssp_rtl_pass_info); - -#if BUILDING_GCC_VERSION >= 9000 - register_callback(plugin_info->base_name, PLUGIN_START_UNIT, - arm_pertask_ssp_start_unit, NULL); -#endif - - return 0; -} -- cgit v1.2.3 From 5e88c48cb4bcbd0ea683373a106268933bb4edd2 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 18 Apr 2025 14:32:39 -0700 Subject: kbuild: Switch from -Wvla to -Wvla-larger-than=1 Variable Length Arrays (VLAs) on the stack must not be used in the kernel. Function parameter VLAs[1] should be usable, but -Wvla will warn for those. For example, this will produce a warning but it is not using a stack VLA: int something(size_t n, int array[n]) { ... Clang has no way yet to distinguish between the VLA types[2], so depend on GCC for now to keep stack VLAs out of the tree by using GCC's -Wvla-larger-than=N option (though GCC may split -Wvla similarly[3] to how Clang is planning to). While GCC 8+ supports -Wvla-larger-than, only 9+ supports ...=0[4], so use -Wvla-larger-than=1. Adjust mm/kasan/Makefile to remove it from CFLAGS (GCC <9 appears unable to disable the warning correctly[5]). The VLA usage in lib/test_ubsan.c was removed in commit 9d7ca61b1366 ("lib/test_ubsan.c: VLA no longer used in kernel") so the lib/Makefile disabling of VLA checking can be entirely removed. Link: https://en.cppreference.com/w/c/language/array [1] Link: https://github.com/llvm/llvm-project/issues/57098 [2] Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98217 [3] Link: https://lore.kernel.org/lkml/7780883c-0ac8-4aaa-b850-469e33b50672@linux.ibm.com/ [4] Link: https://lore.kernel.org/r/202505071331.4iOzqmuE-lkp@intel.com/ [5] Reviewed-by: Nathan Chancellor Reviewed-by: Christoph Hellwig Tested-by: Venkat Rao Bagalkote Link: https://lore.kernel.org/r/20250418213235.work.532-kees@kernel.org Signed-off-by: Kees Cook --- lib/Makefile | 1 - mm/kasan/Makefile | 3 ++- scripts/Makefile.extrawarn | 9 +++++++-- 3 files changed, 9 insertions(+), 4 deletions(-) (limited to 'scripts') diff --git a/lib/Makefile b/lib/Makefile index f07b24ce1b3f..c38582f187dd 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -71,7 +71,6 @@ CFLAGS_test_bitops.o += -Werror obj-$(CONFIG_TEST_SYSCTL) += test_sysctl.o obj-$(CONFIG_TEST_IDA) += test_ida.o obj-$(CONFIG_TEST_UBSAN) += test_ubsan.o -CFLAGS_test_ubsan.o += $(call cc-disable-warning, vla) CFLAGS_test_ubsan.o += $(call cc-disable-warning, unused-but-set-variable) UBSAN_SANITIZE_test_ubsan.o := y obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile index 1a958e7c8a46..dd93ae8a6beb 100644 --- a/mm/kasan/Makefile +++ b/mm/kasan/Makefile @@ -35,7 +35,7 @@ CFLAGS_shadow.o := $(CC_FLAGS_KASAN_RUNTIME) CFLAGS_hw_tags.o := $(CC_FLAGS_KASAN_RUNTIME) CFLAGS_sw_tags.o := $(CC_FLAGS_KASAN_RUNTIME) -CFLAGS_KASAN_TEST := $(CFLAGS_KASAN) $(call cc-disable-warning, vla) +CFLAGS_KASAN_TEST := $(CFLAGS_KASAN) ifndef CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX # If compiler instruments memintrinsics by prefixing them with __asan/__hwasan, # we need to treat them normally (as builtins), otherwise the compiler won't @@ -44,6 +44,7 @@ ifndef CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX CFLAGS_KASAN_TEST += -fno-builtin endif +CFLAGS_REMOVE_kasan_test_c.o += $(call cc-option, -Wvla-larger-than=1) CFLAGS_kasan_test_c.o := $(CFLAGS_KASAN_TEST) RUSTFLAGS_kasan_test_rust.o := $(RUSTFLAGS_KASAN) diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn index 2d6e59561c9d..59d3d196fe4f 100644 --- a/scripts/Makefile.extrawarn +++ b/scripts/Makefile.extrawarn @@ -45,8 +45,13 @@ endif # These result in bogus false positives KBUILD_CFLAGS += $(call cc-disable-warning, dangling-pointer) -# Variable Length Arrays (VLAs) should not be used anywhere in the kernel -KBUILD_CFLAGS += -Wvla +# Stack Variable Length Arrays (VLAs) must not be used in the kernel. +# Function array parameters should, however, be usable, but -Wvla will +# warn for those. Clang has no way yet to distinguish between the VLA +# types, so depend on GCC for now to keep stack VLAs out of the tree. +# https://github.com/llvm/llvm-project/issues/57098 +# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98217 +KBUILD_CFLAGS += $(call cc-option,-Wvla-larger-than=1) # disable pointer signed / unsigned warnings in gcc 4.0 KBUILD_CFLAGS += -Wno-pointer-sign -- cgit v1.2.3 From 0cecd37daef3d57e6656c0023978d5ec2d7409c1 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Sat, 3 May 2025 11:46:18 -0700 Subject: gcc-plugins: Force full rebuild when plugins change There was no dependency between the plugins changing and the rest of the kernel being built. This could cause strange behaviors as instrumentation could vary between targets depending on when they were built. Generate a new header file, gcc-plugins.h, any time the GCC plugins change. Include the header file in compiler-version.h when its associated feature name, GCC_PLUGINS, is defined. This will be picked up by fixdep and force rebuilds where needed. Add a generic "touch" kbuild command, which will be used again in a following patch. Add a "normalize_path" string helper to make the "TOUCH" output less ugly. Link: https://lore.kernel.org/r/20250503184623.2572355-1-kees@kernel.org Tested-by: Nicolas Schier Reviewed-by: Nicolas Schier Signed-off-by: Kees Cook --- include/linux/compiler-version.h | 11 +++++++++++ scripts/Makefile.gcc-plugins | 2 +- scripts/Makefile.lib | 18 ++++++++++++++++++ scripts/gcc-plugins/Makefile | 4 ++++ 4 files changed, 34 insertions(+), 1 deletion(-) (limited to 'scripts') diff --git a/include/linux/compiler-version.h b/include/linux/compiler-version.h index 573fa85b6c0c..5dba398a9412 100644 --- a/include/linux/compiler-version.h +++ b/include/linux/compiler-version.h @@ -12,3 +12,14 @@ * and add dependency on include/config/CC_VERSION_TEXT, which is touched * by Kconfig when the version string from the compiler changes. */ + +/* Additional tree-wide dependencies start here. */ + +/* + * If any of the GCC plugins change, we need to rebuild everything that + * was built with them, as they may have changed their behavior and those + * behaviors may need to be synchronized across all translation units. + */ +#ifdef GCC_PLUGINS +#include +#endif diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins index 5b8a8378ca8a..e50dc931be49 100644 --- a/scripts/Makefile.gcc-plugins +++ b/scripts/Makefile.gcc-plugins @@ -38,7 +38,7 @@ export DISABLE_STACKLEAK_PLUGIN # All the plugin CFLAGS are collected here in case a build target needs to # filter them out of the KBUILD_CFLAGS. -GCC_PLUGINS_CFLAGS := $(strip $(addprefix -fplugin=$(objtree)/scripts/gcc-plugins/, $(gcc-plugin-y)) $(gcc-plugin-cflags-y)) +GCC_PLUGINS_CFLAGS := $(strip $(addprefix -fplugin=$(objtree)/scripts/gcc-plugins/, $(gcc-plugin-y)) $(gcc-plugin-cflags-y)) -DGCC_PLUGINS export GCC_PLUGINS_CFLAGS # Add the flags to the build! diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 2fe73cda0bdd..6fc2a82ee3bb 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -296,6 +296,19 @@ $(foreach m, $1, \ $(addprefix $(obj)/, $(call suffix-search, $(patsubst $(obj)/%,%,$m), $2, $3)))) endef +# Remove ".." and "." from a path, without using "realpath" +# Usage: +# $(call normalize_path,path/to/../file) +define normalize_path +$(strip $(eval elements :=) \ +$(foreach elem,$(subst /, ,$1), \ + $(if $(filter-out .,$(elem)), \ + $(if $(filter ..,$(elem)), \ + $(eval elements := $(wordlist 2,$(words $(elements)),x $(elements))), \ + $(eval elements := $(elements) $(elem))))) \ +$(subst $(space),/,$(elements))) +endef + # Build commands # =========================================================================== # These are shared by some Makefile.* files. @@ -343,6 +356,11 @@ quiet_cmd_copy = COPY $@ $(obj)/%: $(src)/%_shipped $(call cmd,copy) +# Touch a file +# =========================================================================== +quiet_cmd_touch = TOUCH $(call normalize_path,$@) + cmd_touch = touch $@ + # Commands useful for building a boot image # =========================================================================== # diff --git a/scripts/gcc-plugins/Makefile b/scripts/gcc-plugins/Makefile index 320afd3cf8e8..05b14aba41ef 100644 --- a/scripts/gcc-plugins/Makefile +++ b/scripts/gcc-plugins/Makefile @@ -66,3 +66,7 @@ quiet_cmd_plugin_cxx_o_c = HOSTCXX $@ $(plugin-objs): $(obj)/%.o: $(src)/%.c FORCE $(call if_changed_dep,plugin_cxx_o_c) + +$(obj)/../../include/generated/gcc-plugins.h: $(plugin-single) $(plugin-multi) FORCE + $(call if_changed,touch) +always-y += ../../include/generated/gcc-plugins.h -- cgit v1.2.3 From 11bb1678e249e51cd748e8f91e5241b3ce71da3a Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Sat, 3 May 2025 11:46:20 -0700 Subject: integer-wrap: Force full rebuild when .scl file changes Since the integer wrapping sanitizer's behavior depends on its associated .scl file, we must force a full rebuild if the file changes. If not, instrumentation may differ between targets based on when they were built. Generate a new header file, integer-wrap.h, any time the Clang .scl file changes. Include the header file in compiler-version.h when its associated feature name, INTEGER_WRAP, is defined. This will be picked up by fixdep and force rebuilds where needed. Acked-by: Justin Stitt Link: https://lore.kernel.org/r/20250503184623.2572355-3-kees@kernel.org Reviewed-by: Nicolas Schier Signed-off-by: Kees Cook --- include/linux/compiler-version.h | 10 ++++++++++ scripts/Makefile.ubsan | 1 + scripts/basic/Makefile | 5 +++++ 3 files changed, 16 insertions(+) (limited to 'scripts') diff --git a/include/linux/compiler-version.h b/include/linux/compiler-version.h index 4b9d39b37650..ac1665a98a15 100644 --- a/include/linux/compiler-version.h +++ b/include/linux/compiler-version.h @@ -32,3 +32,13 @@ #ifdef RANDSTRUCT #include #endif + +/* + * If any external changes affect Clang's integer wrapping sanitizer + * behavior, a full rebuild is needed as the coverage for wrapping types + * may have changed, which may impact the expected behaviors that should + * not differ between compilation units. + */ +#ifdef INTEGER_WRAP +#include +#endif diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan index 9e35198edbf0..653f7117819c 100644 --- a/scripts/Makefile.ubsan +++ b/scripts/Makefile.ubsan @@ -15,6 +15,7 @@ ubsan-cflags-$(CONFIG_UBSAN_TRAP) += $(call cc-option,-fsanitize-trap=undefined export CFLAGS_UBSAN := $(ubsan-cflags-y) ubsan-integer-wrap-cflags-$(CONFIG_UBSAN_INTEGER_WRAP) += \ + -DINTEGER_WRAP \ -fsanitize-undefined-ignore-overflow-pattern=all \ -fsanitize=signed-integer-overflow \ -fsanitize=unsigned-integer-overflow \ diff --git a/scripts/basic/Makefile b/scripts/basic/Makefile index dd289a6725ac..fb8e2c38fbc7 100644 --- a/scripts/basic/Makefile +++ b/scripts/basic/Makefile @@ -14,3 +14,8 @@ cmd_create_randstruct_seed = \ $(obj)/randstruct.seed: $(gen-randstruct-seed) FORCE $(call if_changed,create_randstruct_seed) always-$(CONFIG_RANDSTRUCT) += randstruct.seed + +# integer-wrap: if the .scl file changes, we need to do a full rebuild. +$(obj)/../../include/generated/integer-wrap.h: $(srctree)/scripts/integer-wrap-ignore.scl FORCE + $(call if_changed,touch) +always-$(CONFIG_UBSAN_INTEGER_WRAP) += ../../include/generated/integer-wrap.h -- cgit v1.2.3 From e136a4062174a9a8d1c1447ca040ea81accfa6a8 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Sat, 26 Apr 2025 00:37:52 -0700 Subject: randstruct: gcc-plugin: Remove bogus void member MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When building the randomized replacement tree of struct members, the randstruct GCC plugin would insert, as the first member, a 0-sized void member. This appears as though it was done to catch non-designated ("unnamed") static initializers, which wouldn't be stable since they depend on the original struct layout order. This was accomplished by having the side-effect of the "void member" tripping an assert in GCC internals (count_type_elements) if the member list ever needed to be counted (e.g. for figuring out the order of members during a non-designated initialization), which would catch impossible type (void) in the struct: security/landlock/fs.c: In function ‘hook_file_ioctl_common’: security/landlock/fs.c:1745:61: internal compiler error: in count_type_elements, at expr.cc:7075 1745 | .u.op = &(struct lsm_ioctlop_audit) { | ^ static HOST_WIDE_INT count_type_elements (const_tree type, bool for_ctor_p) { switch (TREE_CODE (type)) ... case VOID_TYPE: default: gcc_unreachable (); } } However this is a redundant safety measure since randstruct uses the __designated_initializer attribute both internally and within the __randomized_layout attribute macro so that this would be enforced by the compiler directly even when randstruct was not enabled (via -Wdesignated-init). A recent change in Landlock ended up tripping the same member counting routine when using a full-struct copy initializer as part of an anonymous initializer. This, however, is a false positive as the initializer is copying between identical structs (and hence identical layouts). The "path" member is "struct path", a randomized struct, and is being copied to from another "struct path", the "f_path" member: landlock_log_denial(landlock_cred(file->f_cred), &(struct landlock_request) { .type = LANDLOCK_REQUEST_FS_ACCESS, .audit = { .type = LSM_AUDIT_DATA_IOCTL_OP, .u.op = &(struct lsm_ioctlop_audit) { .path = file->f_path, .cmd = cmd, }, }, ... As can be seen with the coming randstruct KUnit test, there appears to be no behavioral problems with this kind of initialization when the void member is removed from the randstruct GCC plugin, so remove it. Reported-by: "Dr. David Alan Gilbert" Closes: https://lore.kernel.org/lkml/Z_PRaKx7q70MKgCA@gallifrey/ Reported-by: Mark Brown Closes: https://lore.kernel.org/lkml/20250407-kbuild-disable-gcc-plugins-v1-1-5d46ae583f5e@kernel.org/ Reported-by: WangYuli Closes: https://lore.kernel.org/lkml/337D5D4887277B27+3c677db3-a8b9-47f0-93a4-7809355f1381@uniontech.com/ Fixes: 313dd1b62921 ("gcc-plugins: Add the randstruct plugin") Signed-off-by: Kees Cook --- scripts/gcc-plugins/randomize_layout_plugin.c | 18 +----------------- 1 file changed, 1 insertion(+), 17 deletions(-) (limited to 'scripts') diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c index 5694df3da2e9..971a1908a8cc 100644 --- a/scripts/gcc-plugins/randomize_layout_plugin.c +++ b/scripts/gcc-plugins/randomize_layout_plugin.c @@ -344,29 +344,13 @@ static int relayout_struct(tree type) shuffle(type, (tree *)newtree, shuffle_length); - /* - * set up a bogus anonymous struct field designed to error out on unnamed struct initializers - * as gcc provides no other way to detect such code - */ - list = make_node(FIELD_DECL); - TREE_CHAIN(list) = newtree[0]; - TREE_TYPE(list) = void_type_node; - DECL_SIZE(list) = bitsize_zero_node; - DECL_NONADDRESSABLE_P(list) = 1; - DECL_FIELD_BIT_OFFSET(list) = bitsize_zero_node; - DECL_SIZE_UNIT(list) = size_zero_node; - DECL_FIELD_OFFSET(list) = size_zero_node; - DECL_CONTEXT(list) = type; - // to satisfy the constify plugin - TREE_READONLY(list) = 1; - for (i = 0; i < num_fields - 1; i++) TREE_CHAIN(newtree[i]) = newtree[i+1]; TREE_CHAIN(newtree[num_fields - 1]) = NULL_TREE; main_variant = TYPE_MAIN_VARIANT(type); for (variant = main_variant; variant; variant = TYPE_NEXT_VARIANT(variant)) { - TYPE_FIELDS(variant) = list; + TYPE_FIELDS(variant) = newtree[0]; TYPE_ATTRIBUTES(variant) = copy_list(TYPE_ATTRIBUTES(variant)); TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("randomize_performed"), NULL_TREE, TYPE_ATTRIBUTES(variant)); TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("designated_init"), NULL_TREE, TYPE_ATTRIBUTES(variant)); -- cgit v1.2.3