Merge tag 'gcc-plugins-v4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull GCC plugin updates from Kees Cook:
 "The big part is the randstruct plugin infrastructure.

  This is the first of two expected pull requests for randstruct since
  there are dependencies in other trees that would be easier to merge
  once those have landed. Notably, the IPC allocation refactoring in
  -mm, and many trivial merge conflicts across several trees when
  applying the __randomize_layout annotation.

  As a result, it seemed like I should send this now since it is
  relatively self-contained, and once the rest of the trees have landed,
  send the annotation patches. I'm expecting the final phase of
  randstruct (automatic struct selection) will land for v4.14, but if
  its other tree dependencies actually make it for v4.13, I can send
  that merge request too.

  Summary:

  - typo fix in Kconfig (Jean Delvare)

  - randstruct infrastructure"

* tag 'gcc-plugins-v4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  ARM: Prepare for randomized task_struct
  randstruct: Whitelist NIU struct page overloading
  randstruct: Whitelist big_key path struct overloading
  randstruct: Whitelist UNIXCB cast
  randstruct: Whitelist struct security_hook_heads cast
  gcc-plugins: Add the randstruct plugin
  Fix English in description of GCC_PLUGIN_STRUCTLEAK
  compiler: Add __designated_init annotation
  gcc-plugins: Detail c-common.h location for GCC 4.6

6 files changed, 1061 insertions, 0 deletions

diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins
index 8233553..2e0e2ea 100644
--- a/scripts/Makefile.gcc-plugins
+++ b/scripts/Makefile.gcc-plugins
@@ -29,6 +29,10 @@ ifdef CONFIG_GCC_PLUGINS
   gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK_VERBOSE)	+= -fplugin-arg-structleak_plugin-verbose
   gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK)	+= -DSTRUCTLEAK_PLUGIN
 
+  gcc-plugin-$(CONFIG_GCC_PLUGIN_RANDSTRUCT)	+= randomize_layout_plugin.so
+  gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_RANDSTRUCT)	+= -DRANDSTRUCT_PLUGIN
+  gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_RANDSTRUCT_PERFORMANCE)	+= -fplugin-arg-randomize_layout_plugin-performance-mode
+
   GCC_PLUGINS_CFLAGS := $(strip $(addprefix -fplugin=$(objtree)/scripts/gcc-plugins/, $(gcc-plugin-y)) $(gcc-plugin-cflags-y))
 
   export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGIN GCC_PLUGIN_SUBDIR
diff --git a/scripts/gcc-plugins/.gitignore b/scripts/gcc-plugins/.gitignore
new file mode 100644
index 0000000..de92ed9
--- /dev/null
+++ b/scripts/gcc-plugins/.gitignore
@@ -0,0 +1 @@
+randomize_layout_seed.h
diff --git a/scripts/gcc-plugins/Makefile b/scripts/gcc-plugins/Makefile
index 8b29dc1..214eb23 100644
--- a/scripts/gcc-plugins/Makefile
+++ b/scripts/gcc-plugins/Makefile
@@ -18,6 +18,14 @@ endif
 
 export HOSTLIBS
 
+$(obj)/randomize_layout_plugin.o: $(objtree)/$(obj)/randomize_layout_seed.h
+quiet_cmd_create_randomize_layout_seed = GENSEED $@
+cmd_create_randomize_layout_seed = \
+  $(CONFIG_SHELL) $(srctree)/$(src)/gen-random-seed.sh $@ $(objtree)/include/generated/randomize_layout_hash.h
+$(objtree)/$(obj)/randomize_layout_seed.h: FORCE
+	$(call if_changed,create_randomize_layout_seed)
+targets = randomize_layout_seed.h randomize_layout_hash.h
+
 $(HOSTLIBS)-y := $(foreach p,$(GCC_PLUGIN),$(if $(findstring /,$(p)),,$(p)))
 always := $($(HOSTLIBS)-y)
 
diff --git a/scripts/gcc-plugins/gcc-common.h b/scripts/gcc-plugins/gcc-common.h
index b232ab1..6948898 100644
--- a/scripts/gcc-plugins/gcc-common.h
+++ b/scripts/gcc-plugins/gcc-common.h
@@ -63,6 +63,13 @@
 #endif
 
 #if BUILDING_GCC_VERSION >= 4006
+/*
+ * The c-family headers were moved into a subdirectory in GCC version
+ * 4.7, but most plugin-building users of GCC 4.6 are using the Debian
+ * or Ubuntu package, which has an out-of-tree patch to move this to the
+ * same location as found in 4.7 and later:
+ * https://sources.debian.net/src/gcc-4.6/4.6.3-14/debian/patches/pr45078.diff/
+ */
 #include "c-family/c-common.h"
 #else
 #include "c-common.h"
@@ -946,4 +953,9 @@ static inline void debug_gimple_stmt(const_gimple s)
 	get_inner_reference(exp, pbitsize, pbitpos, poffset, pmode, punsignedp, preversep, pvolatilep)
 #endif
 
+#if BUILDING_GCC_VERSION < 7000
+#define SET_DECL_ALIGN(decl, align)	DECL_ALIGN(decl) = (align)
+#define SET_DECL_MODE(decl, mode)	DECL_MODE(decl) = (mode)
+#endif
+
 #endif
diff --git a/scripts/gcc-plugins/gen-random-seed.sh b/scripts/gcc-plugins/gen-random-seed.sh
new file mode 100644
index 0000000..7514850
--- /dev/null
+++ b/scripts/gcc-plugins/gen-random-seed.sh
@@ -0,0 +1,8 @@
+#!/bin/sh
+
+if [ ! -f "$1" ]; then
+	SEED=`od -A n -t x8 -N 32 /dev/urandom | tr -d ' \n'`
+	echo "const char *randstruct_seed = \"$SEED\";" > "$1"
+	HASH=`echo -n "$SEED" | sha256sum | cut -d" " -f1 | tr -d ' \n'`
+	echo "#define RANDSTRUCT_HASHED_SEED \"$HASH\"" > "$2"
+fi
diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c
new file mode 100644
index 0000000..cdaac8c
--- /dev/null
+++ b/scripts/gcc-plugins/randomize_layout_plugin.c
@@ -0,0 +1,1028 @@
+/*
+ * Copyright 2014-2016 by Open Source Security, Inc., Brad Spengler <spender@grsecurity.net>
+ *                   and PaX Team <pageexec@freemail.hu>
+ * Licensed under the GPL v2
+ *
+ * Note: the choice of the license means that the compilation process is
+ *       NOT 'eligible' as defined by gcc's library exception to the GPL v3,
+ *       but for the kernel it doesn't matter since it doesn't link against
+ *       any of the gcc libraries
+ *
+ * Usage:
+ * $ # for 4.5/4.6/C based 4.7
+ * $ gcc -I`gcc -print-file-name=plugin`/include -I`gcc -print-file-name=plugin`/include/c-family -fPIC -shared -O2 -o randomize_layout_plugin.so randomize_layout_plugin.c
+ * $ # for C++ based 4.7/4.8+
+ * $ g++ -I`g++ -print-file-name=plugin`/include -I`g++ -print-file-name=plugin`/include/c-family -fPIC -shared -O2 -o randomize_layout_plugin.so randomize_layout_plugin.c
+ * $ gcc -fplugin=./randomize_layout_plugin.so test.c -O2
+ */
+
+#include "gcc-common.h"
+#include "randomize_layout_seed.h"
+
+#if BUILDING_GCC_MAJOR < 4 || (BUILDING_GCC_MAJOR == 4 && BUILDING_GCC_MINOR < 7)
+#error "The RANDSTRUCT plugin requires GCC 4.7 or newer."
+#endif
+
+#define ORIG_TYPE_NAME(node) \
+	(TYPE_NAME(TYPE_MAIN_VARIANT(node)) != NULL_TREE ? ((const unsigned char *)IDENTIFIER_POINTER(TYPE_NAME(TYPE_MAIN_VARIANT(node)))) : (const unsigned char *)"anonymous")
+
+#define INFORM(loc, msg, ...)	inform(loc, "randstruct: " msg, ##__VA_ARGS__)
+#define MISMATCH(loc, how, ...)	INFORM(loc, "casting between randomized structure pointer types (" how "): %qT and %qT\n", __VA_ARGS__)
+
+__visible int plugin_is_GPL_compatible;
+
+static int performance_mode;
+
+static struct plugin_info randomize_layout_plugin_info = {
+	.version	= "201402201816vanilla",
+	.help		= "disable\t\t\tdo not activate plugin\n"
+			  "performance-mode\tenable cacheline-aware layout randomization\n"
+};
+
+struct whitelist_entry {
+	const char *pathname;
+	const char *lhs;
+	const char *rhs;
+};
+
+static const struct whitelist_entry whitelist[] = {
+	/* NIU overloads mapping with page struct */
+	{ "drivers/net/ethernet/sun/niu.c", "page", "address_space" },
+	/* unix_skb_parms via UNIXCB() buffer */
+	{ "net/unix/af_unix.c", "unix_skb_parms", "char" },
+	/* big_key payload.data struct splashing */
+	{ "security/keys/big_key.c", "path", "void *" },
+	/* walk struct security_hook_heads as an array of struct list_head */
+	{ "security/security.c", "list_head", "security_hook_heads" },
+	{ }
+};
+
+/* from old Linux dcache.h */
+static inline unsigned long
+partial_name_hash(unsigned long c, unsigned long prevhash)
+{
+	return (prevhash + (c << 4) + (c >> 4)) * 11;
+}
+static inline unsigned int
+name_hash(const unsigned char *name)
+{
+	unsigned long hash = 0;
+	unsigned int len = strlen((const char *)name);
+	while (len--)
+		hash = partial_name_hash(*name++, hash);
+	return (unsigned int)hash;
+}
+
+static tree handle_randomize_layout_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs)
+{
+	tree type;
+
+	*no_add_attrs = true;
+	if (TREE_CODE(*node) == FUNCTION_DECL) {
+		error("%qE attribute does not apply to functions (%qF)", name, *node);
+		return NULL_TREE;
+	}
+
+	if (TREE_CODE(*node) == PARM_DECL) {
+		error("%qE attribute does not apply to function parameters (%qD)", name, *node);
+		return NULL_TREE;
+	}
+
+	if (TREE_CODE(*node) == VAR_DECL) {
+		error("%qE attribute does not apply to variables (%qD)", name, *node);
+		return NULL_TREE;
+	}
+
+	if (TYPE_P(*node)) {
+		type = *node;
+	} else {
+		gcc_assert(TREE_CODE(*node) == TYPE_DECL);
+		type = TREE_TYPE(*node);
+	}
+
+	if (TREE_CODE(type) != RECORD_TYPE) {
+		error("%qE attribute used on %qT applies to struct types only", name, type);
+		return NULL_TREE;
+	}
+
+	if (lookup_attribute(IDENTIFIER_POINTER(name), TYPE_ATTRIBUTES(type))) {
+		error("%qE attribute is already applied to the type %qT", name, type);
+		return NULL_TREE;
+	}
+
+	*no_add_attrs = false;
+
+	return NULL_TREE;
+}
+
+/* set on complete types that we don't need to inspect further at all */
+static tree handle_randomize_considered_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs)
+{
+	*no_add_attrs = false;
+	return NULL_TREE;
+}
+
+/*
+ * set on types that we've performed a shuffle on, to prevent re-shuffling
+ * this does not preclude us from inspecting its fields for potential shuffles
+ */
+static tree handle_randomize_performed_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs)
+{
+	*no_add_attrs = false;
+	return NULL_TREE;
+}
+
+/*
+ * 64bit variant of Bob Jenkins' public domain PRNG
+ * 256 bits of internal state
+ */
+
+typedef unsigned long long u64;
+
+typedef struct ranctx { u64 a; u64 b; u64 c; u64 d; } ranctx;
+
+#define rot(x,k) (((x)<<(k))|((x)>>(64-(k))))
+static u64 ranval(ranctx *x) {
+	u64 e = x->a - rot(x->b, 7);
+	x->a = x->b ^ rot(x->c, 13);
+	x->b = x->c + rot(x->d, 37);
+	x->c = x->d + e;
+	x->d = e + x->a;
+	return x->d;
+}
+
+static void raninit(ranctx *x, u64 *seed) {
+	int i;
+
+	x->a = seed[0];
+	x->b = seed[1];
+	x->c = seed[2];
+	x->d = seed[3];
+
+	for (i=0; i < 30; ++i)
+		(void)ranval(x);
+}
+
+static u64 shuffle_seed[4];
+
+struct partition_group {
+	tree tree_start;
+	unsigned long start;
+	unsigned long length;
+};
+
+static void partition_struct(tree *fields, unsigned long length, struct partition_group *size_groups, unsigned long *num_groups)
+{
+	unsigned long i;
+	unsigned long accum_size = 0;
+	unsigned long accum_length = 0;
+	unsigned long group_idx = 0;
+
+	gcc_assert(length < INT_MAX);
+
+	memset(size_groups, 0, sizeof(struct partition_group) * length);
+
+	for (i = 0; i < length; i++) {
+		if (size_groups[group_idx].tree_start == NULL_TREE) {
+			size_groups[group_idx].tree_start = fields[i];
+			size_groups[group_idx].start = i;
+			accum_length = 0;
+			accum_size = 0;
+		}
+		accum_size += (unsigned long)int_size_in_bytes(TREE_TYPE(fields[i]));
+		accum_length++;
+		if (accum_size >= 64) {
+			size_groups[group_idx].length = accum_length;
+			accum_length = 0;
+			group_idx++;
+		}
+	}
+
+	if (size_groups[group_idx].tree_start != NULL_TREE &&
+	    !size_groups[group_idx].length) {
+		size_groups[group_idx].length = accum_length;
+		group_idx++;
+	}
+
+	*num_groups = group_idx;
+}
+
+static void performance_shuffle(tree *newtree, unsigned long length, ranctx *prng_state)
+{
+	unsigned long i, x;
+	struct partition_group size_group[length];
+	unsigned long num_groups = 0;
+	unsigned long randnum;
+
+	partition_struct(newtree, length, (struct partition_group *)&size_group, &num_groups);
+	for (i = num_groups - 1; i > 0; i--) {
+		struct partition_group tmp;
+		randnum = ranval(prng_state) % (i + 1);
+		tmp = size_group[i];
+		size_group[i] = size_group[randnum];
+		size_group[randnum] = tmp;
+	}
+
+	for (x = 0; x < num_groups; x++) {
+		for (i = size_group[x].start + size_group[x].length - 1; i > size_group[x].start; i--) {
+			tree tmp;
+			if (DECL_BIT_FIELD_TYPE(newtree[i]))
+				continue;
+			randnum = ranval(prng_state) % (i + 1);
+			// we could handle this case differently if desired
+			if (DECL_BIT_FIELD_TYPE(newtree[randnum]))
+				continue;
+			tmp = newtree[i];
+			newtree[i] = newtree[randnum];
+			newtree[randnum] = tmp;
+		}
+	}
+}
+
+static void full_shuffle(tree *newtree, unsigned long length, ranctx *prng_state)
+{
+	unsigned long i, randnum;
+
+	for (i = length - 1; i > 0; i--) {
+		tree tmp;
+		randnum = ranval(prng_state) % (i + 1);
+		tmp = newtree[i];
+		newtree[i] = newtree[randnum];
+		newtree[randnum] = tmp;
+	}
+}
+
+/* modern in-place Fisher-Yates shuffle */
+static void shuffle(const_tree type, tree *newtree, unsigned long length)
+{
+	unsigned long i;
+	u64 seed[4];
+	ranctx prng_state;
+	const unsigned char *structname;
+
+	if (length == 0)
+		return;
+
+	gcc_assert(TREE_CODE(type) == RECORD_TYPE);
+
+	structname = ORIG_TYPE_NAME(type);
+
+#ifdef __DEBUG_PLUGIN
+	fprintf(stderr, "Shuffling struct %s %p\n", (const char *)structname, type);
+#ifdef __DEBUG_VERBOSE
+	debug_tree((tree)type);
+#endif
+#endif
+
+	for (i = 0; i < 4; i++) {
+		seed[i] = shuffle_seed[i];
+		seed[i] ^= name_hash(structname);
+	}
+
+	raninit(&prng_state, (u64 *)&seed);
+
+	if (performance_mode)
+		performance_shuffle(newtree, length, &prng_state);
+	else
+		full_shuffle(newtree, length, &prng_state);
+}
+
+static bool is_flexible_array(const_tree field)
+{
+	const_tree fieldtype;
+	const_tree typesize;
+	const_tree elemtype;
+	const_tree elemsize;
+
+	fieldtype = TREE_TYPE(field);
+	typesize = TYPE_SIZE(fieldtype);
+
+	if (TREE_CODE(fieldtype) != ARRAY_TYPE)
+		return false;
+
+	elemtype = TREE_TYPE(fieldtype);
+	elemsize = TYPE_SIZE(elemtype);
+
+	/* size of type is represented in bits */
+
+	if (typesize == NULL_TREE && TYPE_DOMAIN(fieldtype) != NULL_TREE &&
+	    TYPE_MAX_VALUE(TYPE_DOMAIN(fieldtype)) == NULL_TREE)
+		return true;
+
+	if (typesize != NULL_TREE &&
+	    (TREE_CONSTANT(typesize) && (!tree_to_uhwi(typesize) ||
+	     tree_to_uhwi(typesize) == tree_to_uhwi(elemsize))))
+		return true;
+
+	return false;
+}
+
+static int relayout_struct(tree type)
+{
+	unsigned long num_fields = (unsigned long)list_length(TYPE_FIELDS(type));
+	unsigned long shuffle_length = num_fields;
+	tree field;
+	tree newtree[num_fields];
+	unsigned long i;
+	tree list;
+	tree variant;
+	tree main_variant;
+	expanded_location xloc;
+	bool has_flexarray = false;
+
+	if (TYPE_FIELDS(type) == NULL_TREE)
+		return 0;
+
+	if (num_fields < 2)
+		return 0;
+
+	gcc_assert(TREE_CODE(type) == RECORD_TYPE);
+
+	gcc_assert(num_fields < INT_MAX);
+
+	if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)) ||
+	    lookup_attribute("no_randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))))
+		return 0;
+
+	/* Workaround for 3rd-party VirtualBox source that we can't modify ourselves */
+	if (!strcmp((const char *)ORIG_TYPE_NAME(type), "INTNETTRUNKFACTORY") ||
+	    !strcmp((const char *)ORIG_TYPE_NAME(type), "RAWPCIFACTORY"))
+		return 0;
+
+	/* throw out any structs in uapi */
+	xloc = expand_location(DECL_SOURCE_LOCATION(TYPE_FIELDS(type)));
+
+	if (strstr(xloc.file, "/uapi/"))
+		error(G_("attempted to randomize userland API struct %s"), ORIG_TYPE_NAME(type));
+
+	for (field = TYPE_FIELDS(type), i = 0; field; field = TREE_CHAIN(field), i++) {
+		gcc_assert(TREE_CODE(field) == FIELD_DECL);
+		newtree[i] = field;
+	}
+
+	/*
+	 * enforce that we don't randomize the layout of the last
+	 * element of a struct if it's a 0 or 1-length array
+	 * or a proper flexible array
+	 */
+	if (is_flexible_array(newtree[num_fields - 1])) {
+		has_flexarray = true;
+		shuffle_length--;
+	}
+
+	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_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));
+		if (has_flexarray)
+			TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("has_flexarray"), NULL_TREE, TYPE_ATTRIBUTES(type));
+	}
+
+	/*
+	 * force a re-layout of the main variant
+	 * the TYPE_SIZE for all variants will be recomputed
+	 * by finalize_type_size()
+	 */
+	TYPE_SIZE(main_variant) = NULL_TREE;
+	layout_type(main_variant);
+	gcc_assert(TYPE_SIZE(main_variant) != NULL_TREE);
+
+	return 1;
+}
+
+/* from constify plugin */
+static const_tree get_field_type(const_tree field)
+{
+	return strip_array_types(TREE_TYPE(field));
+}
+
+/* from constify plugin */
+static bool is_fptr(const_tree fieldtype)
+{
+	if (TREE_CODE(fieldtype) != POINTER_TYPE)
+		return false;
+
+	return TREE_CODE(TREE_TYPE(fieldtype)) == FUNCTION_TYPE;
+}
+
+/* derived from constify plugin */
+static int is_pure_ops_struct(const_tree node)
+{
+	const_tree field;
+
+	gcc_assert(TREE_CODE(node) == RECORD_TYPE || TREE_CODE(node) == UNION_TYPE);
+
+	/* XXX: Do not apply randomization to all-ftpr structs yet. */
+	return 0;
+
+	for (field = TYPE_FIELDS(node); field; field = TREE_CHAIN(field)) {
+		const_tree fieldtype = get_field_type(field);
+		enum tree_code code = TREE_CODE(fieldtype);
+
+		if (node == fieldtype)
+			continue;
+
+		if (!is_fptr(fieldtype))
+			return 0;
+
+		if (code != RECORD_TYPE && code != UNION_TYPE)
+			continue;
+
+		if (!is_pure_ops_struct(fieldtype))
+			return 0;
+	}
+
+	return 1;
+}
+
+static void randomize_type(tree type)
+{
+	tree variant;
+
+	gcc_assert(TREE_CODE(type) == RECORD_TYPE);
+
+	if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type)))
+		return;
+
+	if (lookup_attribute("randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))) || is_pure_ops_struct(type))
+		relayout_struct(type);
+
+	for (variant = TYPE_MAIN_VARIANT(type); variant; variant = TYPE_NEXT_VARIANT(variant)) {
+		TYPE_ATTRIBUTES(type) = copy_list(TYPE_ATTRIBUTES(type));
+		TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("randomize_considered"), NULL_TREE, TYPE_ATTRIBUTES(type));
+	}
+#ifdef __DEBUG_PLUGIN
+	fprintf(stderr, "Marking randomize_considered on struct %s\n", ORIG_TYPE_NAME(type));
+#ifdef __DEBUG_VERBOSE
+	debug_tree(type);
+#endif
+#endif
+}
+
+static void update_decl_size(tree decl)
+{
+	tree lastval, lastidx, field, init, type, flexsize;
+	unsigned HOST_WIDE_INT len;
+
+	type = TREE_TYPE(decl);
+
+	if (!lookup_attribute("has_flexarray", TYPE_ATTRIBUTES(type)))
+		return;
+
+	init = DECL_INITIAL(decl);
+	if (init == NULL_TREE || init == error_mark_node)
+		return;
+
+	if (TREE_CODE(init) != CONSTRUCTOR)
+		return;
+
+	len = CONSTRUCTOR_NELTS(init);
+        if (!len)
+		return;
+
+	lastval = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->value;
+	lastidx = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->index;
+
+	for (field = TYPE_FIELDS(TREE_TYPE(decl)); TREE_CHAIN(field); field = TREE_CHAIN(field))
+		;
+
+	if (lastidx != field)
+		return;
+
+	if (TREE_CODE(lastval) != STRING_CST) {
+		error("Only string constants are supported as initializers "
+		      "for randomized structures with flexible arrays");
+		return;
+	}
+
+	flexsize = bitsize_int(TREE_STRING_LENGTH(lastval) *
+		tree_to_uhwi(TYPE_SIZE(TREE_TYPE(TREE_TYPE(lastval)))));
+
+	DECL_SIZE(decl) = size_binop(PLUS_EXPR, TYPE_SIZE(type), flexsize);
+
+	return;
+}
+
+
+static void randomize_layout_finish_decl(void *event_data, void *data)
+{
+	tree decl = (tree)event_data;
+	tree type;
+
+	if (decl == NULL_TREE || decl == error_mark_node)
+		return;
+
+	type = TREE_TYPE(decl);
+
+	if (TREE_CODE(decl) != VAR_DECL)
+		return;
+
+	if (TREE_CODE(type) != RECORD_TYPE && TREE_CODE(type) != UNION_TYPE)
+		return;
+
+	if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)))
+		return;
+
+	DECL_SIZE(decl) = 0;
+	DECL_SIZE_UNIT(decl) = 0;
+	SET_DECL_ALIGN(decl, 0);
+	SET_DECL_MODE (decl, VOIDmode);
+	SET_DECL_RTL(decl, 0);
+	update_decl_size(decl);
+	layout_decl(decl, 0);
+}
+
+static void finish_type(void *event_data, void *data)
+{
+	tree type = (tree)event_data;
+
+	if (type == NULL_TREE || type == error_mark_node)
+		return;
+
+	if (TREE_CODE(type) != RECORD_TYPE)
+		return;
+
+	if (TYPE_FIELDS(type) == NULL_TREE)
+		return;
+
+	if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type)))
+		return;
+
+#ifdef __DEBUG_PLUGIN
+	fprintf(stderr, "Calling randomize_type on %s\n", ORIG_TYPE_NAME(type));
+#endif
+#ifdef __DEBUG_VERBOSE
+	debug_tree(type);
+#endif
+	randomize_type(type);
+
+	return;
+}
+
+static struct attribute_spec randomize_layout_attr = {
+	.name		= "randomize_layout",
+	// related to args
+	.min_length	= 0,
+	.max_length	= 0,
+	.decl_required	= false,
+	// need type declaration
+	.type_required	= true,
+	.function_type_required = false,
+	.handler		= handle_randomize_layout_attr,
+#if BUILDING_GCC_VERSION >= 4007
+	.affects_type_identity  = true
+#endif
+};
+
+static struct attribute_spec no_randomize_layout_attr = {
+	.name		= "no_randomize_layout",
+	// related to args
+	.min_length	= 0,
+	.max_length	= 0,
+	.decl_required	= false,
+	// need type declaration
+	.type_required	= true,
+	.function_type_required = false,
+	.handler		= handle_randomize_layout_attr,
+#if BUILDING_GCC_VERSION >= 4007
+	.affects_type_identity  = true
+#endif
+};
+
+static struct attribute_spec randomize_considered_attr = {
+	.name		= "randomize_considered",
+	// related to args
+	.min_length	= 0,
+	.max_length	= 0,
+	.decl_required	= false,
+	// need type declaration
+	.type_required	= true,
+	.function_type_required = false,
+	.handler		= handle_randomize_considered_attr,
+#if BUILDING_GCC_VERSION >= 4007
+	.affects_type_identity  = false
+#endif
+};
+
+static struct attribute_spec randomize_performed_attr = {
+	.name		= "randomize_performed",
+	// related to args
+	.min_length	= 0,
+	.max_length	= 0,
+	.decl_required	= false,
+	// need type declaration
+	.type_required	= true,
+	.function_type_required = false,
+	.handler		= handle_randomize_performed_attr,
+#if BUILDING_GCC_VERSION >= 4007
+	.affects_type_identity  = false
+#endif
+};
+
+static void register_attributes(void *event_data, void *data)
+{
+	register_attribute(&randomize_layout_attr);
+	register_attribute(&no_randomize_layout_attr);
+	register_attribute(&randomize_considered_attr);
+	register_attribute(&randomize_performed_attr);
+}
+
+static void check_bad_casts_in_constructor(tree var, tree init)
+{
+	unsigned HOST_WIDE_INT idx;
+	tree field, val;
+	tree field_type, val_type;
+
+	FOR_EACH_CONSTRUCTOR_ELT(CONSTRUCTOR_ELTS(init), idx, field, val) {
+		if (TREE_CODE(val) == CONSTRUCTOR) {
+			check_bad_casts_in_constructor(var, val);
+			continue;
+		}
+
+		/* pipacs' plugin creates franken-arrays that differ from those produced by
+		   normal code which all have valid 'field' trees. work around this */
+		if (field == NULL_TREE)
+			continue;
+		field_type = TREE_TYPE(field);
+		val_type = TREE_TYPE(val);
+
+		if (TREE_CODE(field_type) != POINTER_TYPE || TREE_CODE(val_type) != POINTER_TYPE)
+			continue;
+
+		if (field_type == val_type)
+			continue;
+
+		field_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(field_type))));
+		val_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(val_type))));
+
+		if (field_type == void_type_node)
+			continue;
+		if (field_type == val_type)
+			continue;
+		if (TREE_CODE(val_type) != RECORD_TYPE)
+			continue;
+
+		if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(val_type)))
+			continue;
+		MISMATCH(DECL_SOURCE_LOCATION(var), "constructor\n", TYPE_MAIN_VARIANT(field_type), TYPE_MAIN_VARIANT(val_type));
+	}
+}
+
+/* derived from the constify plugin */
+static void check_global_variables(void *event_data, void *data)
+{
+	struct varpool_node *node;
+	tree init;
+
+	FOR_EACH_VARIABLE(node) {
+		tree var = NODE_DECL(node);
+		init = DECL_INITIAL(var);
+		if (init == NULL_TREE)
+			continue;
+
+		if (TREE_CODE(init) != CONSTRUCTOR)
+			continue;
+
+		check_bad_casts_in_constructor(var, init);
+	}
+}
+
+static bool dominated_by_is_err(const_tree rhs, basic_block bb)
+{
+	basic_block dom;
+	gimple dom_stmt;
+	gimple call_stmt;
+	const_tree dom_lhs;
+	const_tree poss_is_err_cond;
+	const_tree poss_is_err_func;
+	const_tree is_err_arg;
+
+	dom = get_immediate_dominator(CDI_DOMINATORS, bb);
+	if (!dom)
+		return false;
+
+	dom_stmt = last_stmt(dom);
+	if (!dom_stmt)
+		return false;
+
+	if (gimple_code(dom_stmt) != GIMPLE_COND)
+		return false;
+
+	if (gimple_cond_code(dom_stmt) != NE_EXPR)
+		return false;
+
+	if (!integer_zerop(gimple_cond_rhs(dom_stmt)))
+		return false;
+
+	poss_is_err_cond = gimple_cond_lhs(dom_stmt);
+
+	if (TREE_CODE(poss_is_err_cond) != SSA_NAME)
+		return false;
+
+	call_stmt = SSA_NAME_DEF_STMT(poss_is_err_cond);
+
+	if (gimple_code(call_stmt) != GIMPLE_CALL)
+		return false;
+
+	dom_lhs = gimple_get_lhs(call_stmt);
+	poss_is_err_func = gimple_call_fndecl(call_stmt);
+	if (!poss_is_err_func)
+		return false;
+	if (dom_lhs != poss_is_err_cond)
+		return false;
+	if (strcmp(DECL_NAME_POINTER(poss_is_err_func), "IS_ERR"))
+		return false;
+
+	is_err_arg = gimple_call_arg(call_stmt, 0);
+	if (!is_err_arg)
+		return false;
+
+	if (is_err_arg != rhs)
+		return false;
+
+	return true;
+}
+
+static void handle_local_var_initializers(void)
+{
+	tree var;
+	unsigned int i;
+
+	FOR_EACH_LOCAL_DECL(cfun, i, var) {
+		tree init = DECL_INITIAL(var);
+		if (!init)
+			continue;
+		if (TREE_CODE(init) != CONSTRUCTOR)
+			continue;
+		check_bad_casts_in_constructor(var, init);
+	}
+}
+
+static bool type_name_eq(gimple stmt, const_tree type_tree, const char *wanted_name)
+{
+	const char *type_name;
+
+	if (type_tree == NULL_TREE)
+		return false;
+
+	switch (TREE_CODE(type_tree)) {
+	case RECORD_TYPE:
+		type_name = TYPE_NAME_POINTER(type_tree);
+		break;
+	case INTEGER_TYPE:
+		if (TYPE_PRECISION(type_tree) == CHAR_TYPE_SIZE)
+			type_name = "char";
+		else {
+			INFORM(gimple_location(stmt), "found non-char INTEGER_TYPE cast comparison: %qT\n", type_tree);
+			debug_tree(type_tree);
+			return false;
+		}
+		break;
+	case POINTER_TYPE:
+		if (TREE_CODE(TREE_TYPE(type_tree)) == VOID_TYPE) {
+			type_name = "void *";
+			break;
+		} else {
+			INFORM(gimple_location(stmt), "found non-void POINTER_TYPE cast comparison %qT\n", type_tree);
+			debug_tree(type_tree);
+			return false;
+		}
+	default:
+		INFORM(gimple_location(stmt), "unhandled cast comparison: %qT\n", type_tree);
+		debug_tree(type_tree);
+		return false;
+	}
+
+	return strcmp(type_name, wanted_name) == 0;
+}
+
+static bool whitelisted_cast(gimple stmt, const_tree lhs_tree, const_tree rhs_tree)
+{
+	const struct whitelist_entry *entry;
+	expanded_location xloc = expand_location(gimple_location(stmt));
+
+	for (entry = whitelist; entry->pathname; entry++) {
+		if (!strstr(xloc.file, entry->pathname))
+			continue;
+
+		if (type_name_eq(stmt, lhs_tree, entry->lhs) && type_name_eq(stmt, rhs_tree, entry->rhs))
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ * iterate over all statements to find "bad" casts:
+ * those where the address of the start of a structure is cast
+ * to a pointer of a structure of a different type, or a
+ * structure pointer type is cast to a different structure pointer type
+ */
+static unsigned int find_bad_casts_execute(void)
+{
+	basic_block bb;
+
+	handle_local_var_initializers();
+
+	FOR_EACH_BB_FN(bb, cfun) {
+		gimple_stmt_iterator gsi;
+
+		for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) {
+			gimple stmt;
+			const_tree lhs;
+			const_tree lhs_type;
+			const_tree rhs1;
+			const_tree rhs_type;
+			const_tree ptr_lhs_type;
+			const_tree ptr_rhs_type;
+			const_tree op0;
+			const_tree op0_type;
+			enum tree_code rhs_code;
+
+			stmt = gsi_stmt(gsi);
+
+#ifdef __DEBUG_PLUGIN
+#ifdef __DEBUG_VERBOSE
+			debug_gimple_stmt(stmt);
+			debug_tree(gimple_get_lhs(stmt));
+#endif
+#endif
+
+			if (gimple_code(stmt) != GIMPLE_ASSIGN)
+				continue;
+
+#ifdef __DEBUG_PLUGIN
+#ifdef __DEBUG_VERBOSE
+			debug_tree(gimple_assign_rhs1(stmt));
+#endif
+#endif
+
+
+			rhs_code = gimple_assign_rhs_code(stmt);
+
+			if (rhs_code != ADDR_EXPR && rhs_code != SSA_NAME)
+				continue;
+
+			lhs = gimple_get_lhs(stmt);
+			lhs_type = TREE_TYPE(lhs);
+			rhs1 = gimple_assign_rhs1(stmt);
+			rhs_type = TREE_TYPE(rhs1);
+
+			if (TREE_CODE(rhs_type) != POINTER_TYPE ||
+			    TREE_CODE(lhs_type) != POINTER_TYPE)
+				continue;
+
+			ptr_lhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(lhs_type))));
+			ptr_rhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(rhs_type))));
+
+			if (ptr_rhs_type == void_type_node)
+				continue;
+
+			if (ptr_lhs_type == void_type_node)
+				continue;
+
+			if (dominated_by_is_err(rhs1, bb))
+				continue;
+
+			if (TREE_CODE(ptr_rhs_type) != RECORD_TYPE) {
+#ifndef __DEBUG_PLUGIN
+				if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_lhs_type)))
+#endif
+				{
+					if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type))
+						MISMATCH(gimple_location(stmt), "rhs", ptr_lhs_type, ptr_rhs_type);
+				}
+				continue;
+			}
+
+			if (rhs_code == SSA_NAME && ptr_lhs_type == ptr_rhs_type)
+				continue;
+
+			if (rhs_code == ADDR_EXPR) {
+				op0 = TREE_OPERAND(rhs1, 0);
+
+				if (op0 == NULL_TREE)
+					continue;
+
+				if (TREE_CODE(op0) != VAR_DECL)
+					continue;
+
+				op0_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(op0))));
+				if (op0_type == ptr_lhs_type)
+					continue;
+
+#ifndef __DEBUG_PLUGIN
+				if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(op0_type)))
+#endif
+				{
+					if (!whitelisted_cast(stmt, ptr_lhs_type, op0_type))
+						MISMATCH(gimple_location(stmt), "op0", ptr_lhs_type, op0_type);
+				}
+			} else {
+				const_tree ssa_name_var = SSA_NAME_VAR(rhs1);
+				/* skip bogus type casts introduced by container_of */
+				if (ssa_name_var != NULL_TREE && DECL_NAME(ssa_name_var) && 
+				    !strcmp((const char *)DECL_NAME_POINTER(ssa_name_var), "__mptr"))
+					continue;
+#ifndef __DEBUG_PLUGIN
+				if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_rhs_type)))
+#endif
+				{
+					if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type))
+						MISMATCH(gimple_location(stmt), "ssa", ptr_lhs_type, ptr_rhs_type);
+				}
+			}
+
+		}
+	}
+	return 0;
+}
+
+#define PASS_NAME find_bad_casts
+#define NO_GATE
+#define TODO_FLAGS_FINISH TODO_dump_func
+#include "gcc-generate-gimple-pass.h"
+
+__visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)
+{
+	int i;
+	const char * const plugin_name = plugin_info->base_name;
+	const int argc = plugin_info->argc;
+	const struct plugin_argument * const argv = plugin_info->argv;
+	bool enable = true;
+	int obtained_seed = 0;
+	struct register_pass_info find_bad_casts_pass_info;
+
+	find_bad_casts_pass_info.pass			= make_find_bad_casts_pass();
+	find_bad_casts_pass_info.reference_pass_name	= "ssa";
+	find_bad_casts_pass_info.ref_pass_instance_number	= 1;
+	find_bad_casts_pass_info.pos_op			= PASS_POS_INSERT_AFTER;
+
+	if (!plugin_default_version_check(version, &gcc_version)) {
+		error(G_("incompatible gcc/plugin versions"));
+		return 1;
+	}
+
+	if (strncmp(lang_hooks.name, "GNU C", 5) && !strncmp(lang_hooks.name, "GNU C+", 6)) {
+		inform(UNKNOWN_LOCATION, G_("%s supports C only, not %s"), plugin_name, lang_hooks.name);
+		enable = false;
+	}
+
+	for (i = 0; i < argc; ++i) {
+		if (!strcmp(argv[i].key, "disable")) {
+			enable = false;
+			continue;
+		}
+		if (!strcmp(argv[i].key, "performance-mode")) {
+			performance_mode = 1;
+			continue;
+		}
+		error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
+	}
+
+	if (strlen(randstruct_seed) != 64) {
+		error(G_("invalid seed value supplied for %s plugin"), plugin_name);
+		return 1;
+	}
+	obtained_seed = sscanf(randstruct_seed, "%016llx%016llx%016llx%016llx",
+		&shuffle_seed[0], &shuffle_seed[1], &shuffle_seed[2], &shuffle_seed[3]);
+	if (obtained_seed != 4) {
+		error(G_("Invalid seed supplied for %s plugin"), plugin_name);
+		return 1;
+	}
+
+	register_callback(plugin_name, PLUGIN_INFO, NULL, &randomize_layout_plugin_info);
+	if (enable) {
+		register_callback(plugin_name, PLUGIN_ALL_IPA_PASSES_START, check_global_variables, NULL);
+		register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &find_bad_casts_pass_info);
+		register_callback(plugin_name, PLUGIN_FINISH_TYPE, finish_type, NULL);
+		register_callback(plugin_name, PLUGIN_FINISH_DECL, randomize_layout_finish_decl, NULL);
+	}
+	register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL);
+
+	return 0;
+}