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Date: Thu, 5 May 2016 10:21:07 -0700
From: Michael Leibowitz <michael.leibowitz@...el.com>
To: spender@...ecurity.net,
kernel-hardening@...ts.openwall.com,
keescook@...omium.org,
re.emese@...il.com,
pageexec@...email.hu
Cc: michael.leibowitz@...el.com
Subject: [RFC 1/3] Add struct randomizing plugin
This plugin randomizes the layout of certain structures at compile
time. This introduces two defines __randomize_layout and
__no_randomize_layout. Which, turn, tell the compiler to either try
to randomize or not to randomize the struct in question. This also
requires struct initalization to use the C99 designated initalizer
form.
This feature is ported over from grsecurity. This is largely
unchanged from the Original code written by the PaX Team and Spender.
Signed-off-by: Michael Leibowitz <michael.leibowitz@...el.com>
---
scripts/Makefile.gcc-plugins | 11 +-
scripts/gcc-plugins/.gitignore | 2 +
scripts/gcc-plugins/Makefile | 12 +
scripts/gcc-plugins/gen-random-seed.sh | 9 +
scripts/gcc-plugins/randomize_layout_plugin.c | 935 ++++++++++++++++++++++++++
5 files changed, 968 insertions(+), 1 deletion(-)
create mode 100644 scripts/gcc-plugins/.gitignore
create mode 100644 scripts/gcc-plugins/gen-random-seed.sh
create mode 100644 scripts/gcc-plugins/randomize_layout_plugin.c
diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins
index 33ab13e..9438516 100644
--- a/scripts/Makefile.gcc-plugins
+++ b/scripts/Makefile.gcc-plugins
@@ -19,7 +19,16 @@ ifdef CONFIG_GCC_PLUGINS
endif
endif
- GCC_PLUGINS_CFLAGS := $(addprefix -fplugin=$(objtree)/scripts/gcc-plugins/, $(gcc-plugin-y))
+
+ gcc-plugin-$(CONFIG_GCC_PLUGIN_RANDSTRUCT) += randomize_layout_plugin.so
+ ifdef CONFIG_GCC_PLUGIN_RANDSTRUCT
+ RANDSTRUCT_PLUGIN_CFLAGS := -DRANDSTRUCT_PLUGIN
+ ifdef CONFIG_GCC_PLUGIN_RANDSTRUCT_PERFORMANCE
+ RANDSTRUCT_PLUGIN_CFLAGS += -fplugin-arg-randomize_layout_plugin-performance-mode
+ endif
+ endif
+
+ GCC_PLUGINS_CFLAGS := $(addprefix -fplugin=$(objtree)/scripts/gcc-plugins/, $(gcc-plugin-y)) $(RANDSTRUCT_PLUGIN_CFLAGS)
ifeq ($(PLUGINCC),)
ifneq ($(GCC_PLUGINS_CFLAGS),)
diff --git a/scripts/gcc-plugins/.gitignore b/scripts/gcc-plugins/.gitignore
new file mode 100644
index 0000000..be289ad
--- /dev/null
+++ b/scripts/gcc-plugins/.gitignore
@@ -0,0 +1,2 @@
+# Copyright (c) 2016, Intel Corporation.
+randomize_layout_seed.h
diff --git a/scripts/gcc-plugins/Makefile b/scripts/gcc-plugins/Makefile
index 79164c1..2941ec3 100644
--- a/scripts/gcc-plugins/Makefile
+++ b/scripts/gcc-plugins/Makefile
@@ -17,8 +17,20 @@ $(HOSTLIBS)-$(CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) := cyc_complexity_plugin.so
ifeq ($(CFLAGS_KCOV), -fplugin=$(objtree)/scripts/gcc-plugins/sancov_plugin.so)
$(HOSTLIBS)-$(CONFIG_GCC_PLUGIN_SANCOV) += sancov_plugin.so
endif
+$(HOSTLIBS)-$(CONFIG_GCC_PLUGIN_RANDSTRUCT) += randomize_layout_plugin.so
always := $($(HOSTLIBS)-y)
cyc_complexity_plugin-objs := cyc_complexity_plugin.o
sancov_plugin-objs := sancov_plugin.o
+randomize_layout_plugin-objs := randomize_layout_plugin.o
+
+$(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
diff --git a/scripts/gcc-plugins/gen-random-seed.sh b/scripts/gcc-plugins/gen-random-seed.sh
new file mode 100644
index 0000000..fdab8df
--- /dev/null
+++ b/scripts/gcc-plugins/gen-random-seed.sh
@@ -0,0 +1,9 @@
+#!/bin/sh
+# Copyright (c) 2016, Intel Corporation.
+
+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..757ab6e
--- /dev/null
+++ b/scripts/gcc-plugins/randomize_layout_plugin.c
@@ -0,0 +1,935 @@
+/*
+ * Copyright (c) 2016, Intel Corporation.
+ *
+ * Copyright 2014,2015 by Open Source Security, Inc., Brad Spengler <spender@...ecurity.net>
+ * and PaX Team <pageexec@...email.hu>
+ * Licensed under the GPL v2
+ *
+ * This code owes much to the PAX constify plugin
+ *
+ * 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 < 6) || \
+ (BUILDING_GCC_MAJOR == 4 && BUILDING_GCC_MINOR == 6 && BUILDING_GCC_PATCHLEVEL < 4)
+#error "The RANDSTRUCT plugin requires GCC 4.6.4 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")
+
+int plugin_is_GPL_compatible;
+
+static int performance_mode;
+
+static struct plugin_info randomize_layout_plugin_info = {
+ .version = "201402201816",
+ .help = "disable\t\t\tdo not activate plugin\n"
+ "performance-mode\tenable cacheline-aware layout randomization\n"
+};
+
+/* 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;
+
+ 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));
+ 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;
+}
+
+static const_tree get_field_type(const_tree field)
+{
+ return strip_array_types(TREE_TYPE(field));
+}
+
+static bool is_fptr(const_tree fieldtype)
+{
+ if (TREE_CODE(fieldtype) != POINTER_TYPE)
+ return false;
+
+ return TREE_CODE(TREE_TYPE(fieldtype)) == FUNCTION_TYPE;
+}
+
+static int is_pure_ops_struct(const_tree node)
+{
+ const_tree field;
+
+ gcc_assert(TREE_CODE(node) == RECORD_TYPE || TREE_CODE(node) == UNION_TYPE);
+
+ 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;
+ DECL_ALIGN(decl) = 0;
+ 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;
+ inform(DECL_SOURCE_LOCATION(var), "found mismatched struct pointer types: %qT and %qT\n", TYPE_MAIN_VARIANT(field_type), TYPE_MAIN_VARIANT(val_type));
+ }
+}
+
+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);
+ }
+}
+
+/*
+ * 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
+ inform(gimple_location(stmt), "found mismatched struct pointer types: %qT and %qT\n", 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
+ inform(gimple_location(stmt), "found mismatched struct pointer types: %qT and %qT\n", 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
+ inform(gimple_location(stmt), "found mismatched struct pointer types: %qT and %qT\n", 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"
+
+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;
+}
--
1.9.1
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