Quelle randomize_layout_plugin.c Sprache: C

/*
* 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"

#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 = PLUGIN_VERSION,
.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 if (TREE_CODE(*node) == FIELD_DECL) {
  *no_add_attrs = false;
  return NULL_TREE;
} 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, index;
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);

/* FIXME: this group shuffle is currently a no-op. */
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 (index = size_group[x].length - 1; index > 0; index--) {
   tree tmp;

   i = size_group[x].start + index;
   if (DECL_BIT_FIELD_TYPE(newtree[i]))
    continue;
   randnum = ranval(prng_state) % (index + 1);
   randnum += size_group[x].start;
   // 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;

fieldtype = TREE_TYPE(field);
typesize = TYPE_SIZE(fieldtype);

if (TREE_CODE(fieldtype) != ARRAY_TYPE)
  return false;

/* 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;

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 proper flexible array
*/
if (is_flexible_array(newtree[num_fields - 1])) {
  has_flexarray = true;
  shuffle_length--;
}

shuffle(type, (tree *)newtree, shuffle_length);

for (i = 0; i < num_fields - 1; i++)
  TREE_CHAIN(newtree[i]) = newtree[i+1];
TREE_CHAIN(newtree[num_fields - 1]) = NULL_TREE;

add_type_attr(type, "randomize_performed", NULL_TREE);
add_type_attr(type, "designated_init", NULL_TREE);
if (has_flexarray)
  add_type_attr(type, "has_flexarray", NULL_TREE);

main_variant = TYPE_MAIN_VARIANT(type);
for (variant = main_variant; variant; variant = TYPE_NEXT_VARIANT(variant))
  TYPE_FIELDS(variant) = newtree[0];

/*
* 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);

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 (code == RECORD_TYPE || code == UNION_TYPE) {
   if (!is_pure_ops_struct(fieldtype))
    return 0;
   continue;
  }

  if (!is_fptr(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);

add_type_attr(type, "randomize_considered", NULL_TREE);

#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 = { };
static struct attribute_spec no_randomize_layout_attr = { };
static struct attribute_spec randomize_considered_attr = { };
static struct attribute_spec randomize_performed_attr = { };

static void register_attributes(void *event_data, void *data)
{
randomize_layout_attr.name  = "randomize_layout";
randomize_layout_attr.type_required = true;
randomize_layout_attr.handler  = handle_randomize_layout_attr;
randomize_layout_attr.affects_type_identity = true;

no_randomize_layout_attr.name  = "no_randomize_layout";
no_randomize_layout_attr.type_required = true;
no_randomize_layout_attr.handler = handle_randomize_layout_attr;
no_randomize_layout_attr.affects_type_identity = true;

randomize_considered_attr.name  = "randomize_considered";
randomize_considered_attr.type_required = true;
randomize_considered_attr.handler = handle_randomize_considered_attr;

randomize_performed_attr.name  = "randomize_performed";
randomize_performed_attr.type_required = true;
randomize_performed_attr.handler = handle_randomize_performed_attr;

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);
}
}

/*
* 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
    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
    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
    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;
}

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