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WSL2-Linux-Kernel
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WSL2-Linux-Kernel/scripts/gcc-plugins/randomize_layout_plugin.c

989 строки
26 KiB
C
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/*
* 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 hlist_head */
{ "security/security.c", "hlist_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);
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);
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 = { };
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);
}
}
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;
}
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