From: Maria Matejka Date: Thu, 14 Apr 2022 14:51:18 +0000 (+0200) Subject: Enforcing certain data structure explicit paddings. X-Git-Tag: v3.0-alpha1~171^2~59^2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1d309c4ce6e95b68c64a8f007f6dd2f1830a5707;p=thirdparty%2Fbird.git Enforcing certain data structure explicit paddings. Implicit paddings have undefined values in C. We want the eattr blocks to be comparable by memcmp and eattrs settable directly by structrure literals. This check ensures that all paddings in eattr and bval are explicit and therefore zeroed in all literals. --- diff --git a/aclocal.m4 b/aclocal.m4 index 1613d6803..58c487917 100644 --- a/aclocal.m4 +++ b/aclocal.m4 @@ -1,6 +1,32 @@ dnl ** Additional Autoconf tests for BIRD configure script dnl ** (c) 1999 Martin Mares +AC_DEFUN([BIRD_CHECK_POINTER_ALIGNMENT], +[ + AC_CACHE_CHECK( + [how pointers are aligned], + [bird_cv_pointer_alignment], + AC_COMPILE_IFELSE([ + AC_LANG_PROGRAM( + [ + _Static_assert(_Alignof(void *) == 8, "bad"); + ], [] + ) + ], + [bird_cv_pointer_alignment=8], + AC_COMPILE_IFELSE([ + AC_LANG_PROGRAM( + [ + _Static_assert(_Alignof(void *) == 4, "bad"); + ], [] + ) + ], + [bird_cv_pointer_alignment=4], + [bird_cv_pointer_alignment=unknown] + )) + ) +]) + AC_DEFUN([BIRD_CHECK_THREAD_LOCAL], [ AC_CACHE_CHECK( diff --git a/configure.ac b/configure.ac index 64181d297..321bed95a 100644 --- a/configure.ac +++ b/configure.ac @@ -360,6 +360,13 @@ AC_C_BIGENDIAN( [AC_MSG_ERROR([Cannot determine CPU endianity.])] ) +BIRD_CHECK_POINTER_ALIGNMENT +if test "$bird_cv_pointer_alignment" = "unknown" ; then + AC_MSG_ERROR([Couldn't determine pointer alignment]) +else + AC_DEFINE_UNQUOTED([CPU_POINTER_ALIGNMENT], [$bird_cv_pointer_alignment], [Pointer alignment for macro usage]) +fi + BIRD_CHECK_ANDROID_GLOB if test "$bird_cv_lib_glob" = no ; then AC_MSG_ERROR([glob.h not found.]) diff --git a/lib/Makefile b/lib/Makefile index 853e0a22d..15f757d9d 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -2,6 +2,6 @@ src := a-path.c a-set.c bitmap.c bitops.c blake2s.c blake2b.c checksum.c event.c obj := $(src-o-files) $(all-daemon) -tests_src := a-set_test.c a-path_test.c bitmap_test.c heap_test.c buffer_test.c event_test.c flowspec_test.c bitops_test.c patmatch_test.c fletcher16_test.c slist_test.c checksum_test.c lists_test.c mac_test.c ip_test.c hash_test.c printf_test.c slab_test.c +tests_src := a-set_test.c a-path_test.c bitmap_test.c heap_test.c buffer_test.c event_test.c flowspec_test.c bitops_test.c patmatch_test.c fletcher16_test.c slist_test.c checksum_test.c lists_test.c mac_test.c ip_test.c hash_test.c printf_test.c slab_test.c type_test.c tests_targets := $(tests_targets) $(tests-target-files) tests_objs := $(tests_objs) $(src-o-files) diff --git a/lib/birdlib.h b/lib/birdlib.h index 6f0bab963..9b6e4a169 100644 --- a/lib/birdlib.h +++ b/lib/birdlib.h @@ -9,18 +9,30 @@ #ifndef _BIRD_BIRDLIB_H_ #define _BIRD_BIRDLIB_H_ +#include "sysdep/config.h" #include "lib/alloca.h" /* Ugly structure offset handling macros */ -struct align_probe { char x; long int y; }; - #define OFFSETOF(s, i) ((size_t) &((s *)0)->i) #define SKIP_BACK(s, i, p) ((s *)((char *)p - OFFSETOF(s, i))) #define BIRD_ALIGN(s, a) (((s)+a-1)&~(a-1)) -#define CPU_STRUCT_ALIGN (sizeof(struct align_probe)) +#define CPU_STRUCT_ALIGN (MAX_(_Alignof(void*), _Alignof(u64))) #define BIRD_CPU_ALIGN(s) BIRD_ALIGN((s), CPU_STRUCT_ALIGN) +/* Structure item alignment macros */ + +#define PADDING_NAME(id) _padding_##id +#define PADDING_(id, sz) u8 PADDING_NAME(id)[sz] + +#if CPU_POINTER_ALIGNMENT == 4 +#define PADDING(id, n32, n64) PADDING_(id, n32) +#elif CPU_POINTER_ALIGNMENT == 8 +#define PADDING(id, n32, n64) PADDING_(id, n64) +#else +#error "Strange CPU pointer alignment: " CPU_POINTER_ALIGNMENT +#endif + /* Utility macros */ #define MIN_(a,b) (((a)<(b))?(a):(b)) diff --git a/lib/route.h b/lib/route.h index 431da4d80..ba7bab61e 100644 --- a/lib/route.h +++ b/lib/route.h @@ -144,6 +144,8 @@ typedef struct eattr { byte fresh:1; /* An uncached attribute (e.g. modified in export filter) */ byte undef:1; /* Explicitly undefined */ + PADDING(unused, 0, 4); + union bval u; } eattr; diff --git a/lib/type.h b/lib/type.h index 6d19a2501..e43389f38 100644 --- a/lib/type.h +++ b/lib/type.h @@ -13,9 +13,15 @@ #include "lib/attrs.h" union bval { -#define BVAL_ITEMS \ - u32 data; /* Integer type inherited from eattrs */ \ - u32 i; /* Integer type inherited from filters */ \ +#define BVAL_ITEMS \ + struct { \ + u32 data; /* Integer type inherited from eattrs */ \ + PADDING(data, 0, 4); /* Must be padded on 64-bits */ \ + }; \ + struct { \ + u32 i; /* Integer type inherited from filters */ \ + PADDING(i, 0, 4); /* Must be padded on 64-bits */ \ + }; \ const struct adata *ptr; /* Generic attribute data inherited from eattrs */ \ const struct adata *ad; /* Generic attribute data inherited from filters */ \ diff --git a/lib/type_test.c b/lib/type_test.c new file mode 100644 index 000000000..20e7630b9 --- /dev/null +++ b/lib/type_test.c @@ -0,0 +1,78 @@ +/* + * BIRD Library -- Data Type Alignment Tests + * + * (c) 2022 Maria Matejka + * + * Can be freely distributed and used under the terms of the GNU GPL. + */ + +#include "test/birdtest.h" +#include "lib/type.h" +#include "lib/route.h" + +#define CHECK_ONE(val) \ + for (uint i=0; i $@ + $(Q)echo "#include \"lib/birdlib.h\"\n$(patsubst %,void %(void);\n,$(PROTO_BUILD)) void protos_build_gen(void) { $(patsubst %, %();\n,$(PROTO_BUILD))}" > $@ tests_src := tests_targets := $(tests_targets) $(tests-target-files) diff --git a/nest/bird.h b/nest/bird.h index 55712abe8..931974a0e 100644 --- a/nest/bird.h +++ b/nest/bird.h @@ -9,7 +9,6 @@ #ifndef _BIRD_BIRD_H_ #define _BIRD_BIRD_H_ -#include "sysdep/config.h" #include "lib/birdlib.h" #include "lib/ip.h" #include "lib/net.h"