Updates to the gcc-plugins:

- infrastructure updates (gcc-common.h)
 - introduce structleak plugin for forced initialization of some structures
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 Version: GnuPG v1
 Comment: Kees Cook <kees@outflux.net>
 
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Merge tag 'gcc-plugins-v4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull gcc-plugins updates from Kees Cook:
 "This includes infrastructure updates and the structleak plugin, which
  performs forced initialization of certain structures to avoid possible
  information exposures to userspace.

  Summary:

   - infrastructure updates (gcc-common.h)

   - introduce structleak plugin for forced initialization of some
     structures"

* tag 'gcc-plugins-v4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  gcc-plugins: Add structleak for more stack initialization
  gcc-plugins: consolidate on PASS_INFO macro
  gcc-plugins: add PASS_INFO and build_const_char_string()
This commit is contained in:
Linus Torvalds 2017-02-22 09:05:47 -08:00
commit 1e74a2eb1f
8 changed files with 326 additions and 29 deletions

View File

@ -410,6 +410,28 @@ config GCC_PLUGIN_LATENT_ENTROPY
* https://grsecurity.net/
* https://pax.grsecurity.net/
config GCC_PLUGIN_STRUCTLEAK
bool "Force initialization of variables containing userspace addresses"
depends on GCC_PLUGINS
help
This plugin zero-initializes any structures that containing a
__user attribute. This can prevent some classes of information
exposures.
This plugin was ported from grsecurity/PaX. More information at:
* https://grsecurity.net/
* https://pax.grsecurity.net/
config GCC_PLUGIN_STRUCTLEAK_VERBOSE
bool "Report forcefully initialized variables"
depends on GCC_PLUGIN_STRUCTLEAK
depends on !COMPILE_TEST
help
This option will cause a warning to be printed each time the
structleak plugin finds a variable it thinks needs to be
initialized. Since not all existing initializers are detected
by the plugin, this can produce false positive warnings.
config HAVE_CC_STACKPROTECTOR
bool
help

View File

@ -27,7 +27,11 @@ extern void __chk_user_ptr(const volatile void __user *);
extern void __chk_io_ptr(const volatile void __iomem *);
# define ACCESS_PRIVATE(p, member) (*((typeof((p)->member) __force *) &(p)->member))
#else /* __CHECKER__ */
# define __user
# ifdef STRUCTLEAK_PLUGIN
# define __user __attribute__((user))
# else
# define __user
# endif
# define __kernel
# define __safe
# define __force

View File

@ -25,6 +25,10 @@ ifdef CONFIG_GCC_PLUGINS
endif
endif
gcc-plugin-$(CONFIG_GCC_PLUGIN_STRUCTLEAK) += structleak_plugin.so
gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK_VERBOSE) += -fplugin-arg-structleak_plugin-verbose
gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK) += -DSTRUCTLEAK_PLUGIN
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

View File

@ -52,12 +52,8 @@ static unsigned int cyc_complexity_execute(void)
__visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)
{
const char * const plugin_name = plugin_info->base_name;
struct register_pass_info cyc_complexity_pass_info;
cyc_complexity_pass_info.pass = make_cyc_complexity_pass();
cyc_complexity_pass_info.reference_pass_name = "ssa";
cyc_complexity_pass_info.ref_pass_instance_number = 1;
cyc_complexity_pass_info.pos_op = PASS_POS_INSERT_AFTER;
PASS_INFO(cyc_complexity, "ssa", 1, PASS_POS_INSERT_AFTER);
if (!plugin_default_version_check(version, &gcc_version)) {
error(G_("incompatible gcc/plugin versions"));

View File

@ -26,6 +26,9 @@
#include "except.h"
#include "function.h"
#include "toplev.h"
#if BUILDING_GCC_VERSION >= 5000
#include "expr.h"
#endif
#include "basic-block.h"
#include "intl.h"
#include "ggc.h"
@ -80,6 +83,9 @@
#include "diagnostic.h"
#include "tree-dump.h"
#include "tree-pass.h"
#if BUILDING_GCC_VERSION >= 4009
#include "pass_manager.h"
#endif
#include "predict.h"
#include "ipa-utils.h"
@ -119,20 +125,17 @@
#include "builtins.h"
#endif
/* #include "expr.h" where are you... */
extern rtx emit_move_insn(rtx x, rtx y);
/* missing from basic_block.h... */
extern void debug_dominance_info(enum cdi_direction dir);
extern void debug_dominance_tree(enum cdi_direction dir, basic_block root);
void debug_dominance_info(enum cdi_direction dir);
void debug_dominance_tree(enum cdi_direction dir, basic_block root);
#if BUILDING_GCC_VERSION == 4006
extern void debug_gimple_stmt(gimple);
extern void debug_gimple_seq(gimple_seq);
extern void print_gimple_seq(FILE *, gimple_seq, int, int);
extern void print_gimple_stmt(FILE *, gimple, int, int);
extern void print_gimple_expr(FILE *, gimple, int, int);
extern void dump_gimple_stmt(pretty_printer *, gimple, int, int);
void debug_gimple_stmt(gimple);
void debug_gimple_seq(gimple_seq);
void print_gimple_seq(FILE *, gimple_seq, int, int);
void print_gimple_stmt(FILE *, gimple, int, int);
void print_gimple_expr(FILE *, gimple, int, int);
void dump_gimple_stmt(pretty_printer *, gimple, int, int);
#endif
#define __unused __attribute__((__unused__))
@ -146,6 +149,29 @@ extern void dump_gimple_stmt(pretty_printer *, gimple, int, int);
/* should come from c-tree.h if only it were installed for gcc 4.5... */
#define C_TYPE_FIELDS_READONLY(TYPE) TREE_LANG_FLAG_1(TYPE)
static inline tree build_const_char_string(int len, const char *str)
{
tree cstr, elem, index, type;
cstr = build_string(len, str);
elem = build_type_variant(char_type_node, 1, 0);
index = build_index_type(size_int(len - 1));
type = build_array_type(elem, index);
TREE_TYPE(cstr) = type;
TREE_CONSTANT(cstr) = 1;
TREE_READONLY(cstr) = 1;
TREE_STATIC(cstr) = 1;
return cstr;
}
#define PASS_INFO(NAME, REF, ID, POS) \
struct register_pass_info NAME##_pass_info = { \
.pass = make_##NAME##_pass(), \
.reference_pass_name = REF, \
.ref_pass_instance_number = ID, \
.pos_op = POS, \
}
#if BUILDING_GCC_VERSION == 4005
#define FOR_EACH_LOCAL_DECL(FUN, I, D) \
for (tree vars = (FUN)->local_decls, (I) = 0; \
@ -527,6 +553,8 @@ static inline const greturn *as_a_const_greturn(const_gimple stmt)
#define section_name_prefix LTO_SECTION_NAME_PREFIX
#define fatal_error(loc, gmsgid, ...) fatal_error((gmsgid), __VA_ARGS__)
rtx emit_move_insn(rtx x, rtx y);
typedef struct rtx_def rtx_insn;
static inline const char *get_decl_section_name(const_tree decl)
@ -643,6 +671,11 @@ static inline const greturn *as_a_const_greturn(const_gimple stmt)
#define NODE_DECL(node) (node)->decl
#define cgraph_node_name(node) (node)->name()
#define NODE_IMPLICIT_ALIAS(node) (node)->cpp_implicit_alias
static inline opt_pass *get_pass_for_id(int id)
{
return g->get_passes()->get_pass_for_id(id);
}
#endif
#if BUILDING_GCC_VERSION >= 5000 && BUILDING_GCC_VERSION < 6000

View File

@ -592,12 +592,6 @@ __visible int plugin_init(struct plugin_name_args *plugin_info,
const struct plugin_argument * const argv = plugin_info->argv;
int i;
struct register_pass_info latent_entropy_pass_info;
latent_entropy_pass_info.pass = make_latent_entropy_pass();
latent_entropy_pass_info.reference_pass_name = "optimized";
latent_entropy_pass_info.ref_pass_instance_number = 1;
latent_entropy_pass_info.pos_op = PASS_POS_INSERT_BEFORE;
static const struct ggc_root_tab gt_ggc_r_gt_latent_entropy[] = {
{
.base = &latent_entropy_decl,
@ -609,6 +603,8 @@ __visible int plugin_init(struct plugin_name_args *plugin_info,
LAST_GGC_ROOT_TAB
};
PASS_INFO(latent_entropy, "optimized", 1, PASS_POS_INSERT_BEFORE);
if (!plugin_default_version_check(version, &gcc_version)) {
error(G_("incompatible gcc/plugin versions"));
return 1;

View File

@ -89,7 +89,6 @@ static void sancov_start_unit(void __unused *gcc_data, void __unused *user_data)
__visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)
{
int i;
struct register_pass_info sancov_plugin_pass_info;
const char * const plugin_name = plugin_info->base_name;
const int argc = plugin_info->argc;
const struct plugin_argument * const argv = plugin_info->argv;
@ -107,14 +106,11 @@ __visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gc
};
/* BBs can be split afterwards?? */
sancov_plugin_pass_info.pass = make_sancov_pass();
#if BUILDING_GCC_VERSION >= 4009
sancov_plugin_pass_info.reference_pass_name = "asan";
PASS_INFO(sancov, "asan", 0, PASS_POS_INSERT_BEFORE);
#else
sancov_plugin_pass_info.reference_pass_name = "nrv";
PASS_INFO(sancov, "nrv", 1, PASS_POS_INSERT_BEFORE);
#endif
sancov_plugin_pass_info.ref_pass_instance_number = 0;
sancov_plugin_pass_info.pos_op = PASS_POS_INSERT_BEFORE;
if (!plugin_default_version_check(version, &gcc_version)) {
error(G_("incompatible gcc/plugin versions"));

View File

@ -0,0 +1,246 @@
/*
* Copyright 2013-2017 by 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
*
* gcc plugin to forcibly initialize certain local variables that could
* otherwise leak kernel stack to userland if they aren't properly initialized
* by later code
*
* Homepage: http://pax.grsecurity.net/
*
* Options:
* -fplugin-arg-structleak_plugin-disable
* -fplugin-arg-structleak_plugin-verbose
*
* 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 structleak_plugin.so structleak_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 structleak_plugin.so structleak_plugin.c
* $ gcc -fplugin=./structleak_plugin.so test.c -O2
*
* TODO: eliminate redundant initializers
* increase type coverage
*/
#include "gcc-common.h"
/* unused C type flag in all versions 4.5-6 */
#define TYPE_USERSPACE(TYPE) TYPE_LANG_FLAG_5(TYPE)
__visible int plugin_is_GPL_compatible;
static struct plugin_info structleak_plugin_info = {
.version = "201607271510vanilla",
.help = "disable\tdo not activate plugin\n"
"verbose\tprint all initialized variables\n",
};
static bool verbose;
static tree handle_user_attribute(tree *node, tree name, tree args, int flags, bool *no_add_attrs)
{
*no_add_attrs = true;
/* check for types? for now accept everything linux has to offer */
if (TREE_CODE(*node) != FIELD_DECL)
return NULL_TREE;
*no_add_attrs = false;
return NULL_TREE;
}
static struct attribute_spec user_attr = {
.name = "user",
.min_length = 0,
.max_length = 0,
.decl_required = false,
.type_required = false,
.function_type_required = false,
.handler = handle_user_attribute,
#if BUILDING_GCC_VERSION >= 4007
.affects_type_identity = true
#endif
};
static void register_attributes(void *event_data, void *data)
{
register_attribute(&user_attr);
}
static tree get_field_type(tree field)
{
return strip_array_types(TREE_TYPE(field));
}
static bool is_userspace_type(tree type)
{
tree field;
for (field = TYPE_FIELDS(type); field; field = TREE_CHAIN(field)) {
tree fieldtype = get_field_type(field);
enum tree_code code = TREE_CODE(fieldtype);
if (code == RECORD_TYPE || code == UNION_TYPE)
if (is_userspace_type(fieldtype))
return true;
if (lookup_attribute("user", DECL_ATTRIBUTES(field)))
return true;
}
return false;
}
static void finish_type(void *event_data, void *data)
{
tree type = (tree)event_data;
if (type == NULL_TREE || type == error_mark_node)
return;
#if BUILDING_GCC_VERSION >= 5000
if (TREE_CODE(type) == ENUMERAL_TYPE)
return;
#endif
if (TYPE_USERSPACE(type))
return;
if (is_userspace_type(type))
TYPE_USERSPACE(type) = 1;
}
static void initialize(tree var)
{
basic_block bb;
gimple_stmt_iterator gsi;
tree initializer;
gimple init_stmt;
/* this is the original entry bb before the forced split */
bb = single_succ(ENTRY_BLOCK_PTR_FOR_FN(cfun));
/* first check if variable is already initialized, warn otherwise */
for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) {
gimple stmt = gsi_stmt(gsi);
tree rhs1;
/* we're looking for an assignment of a single rhs... */
if (!gimple_assign_single_p(stmt))
continue;
rhs1 = gimple_assign_rhs1(stmt);
#if BUILDING_GCC_VERSION >= 4007
/* ... of a non-clobbering expression... */
if (TREE_CLOBBER_P(rhs1))
continue;
#endif
/* ... to our variable... */
if (gimple_get_lhs(stmt) != var)
continue;
/* if it's an initializer then we're good */
if (TREE_CODE(rhs1) == CONSTRUCTOR)
return;
}
/* these aren't the 0days you're looking for */
if (verbose)
inform(DECL_SOURCE_LOCATION(var),
"userspace variable will be forcibly initialized");
/* build the initializer expression */
initializer = build_constructor(TREE_TYPE(var), NULL);
/* build the initializer stmt */
init_stmt = gimple_build_assign(var, initializer);
gsi = gsi_after_labels(single_succ(ENTRY_BLOCK_PTR_FOR_FN(cfun)));
gsi_insert_before(&gsi, init_stmt, GSI_NEW_STMT);
update_stmt(init_stmt);
}
static unsigned int structleak_execute(void)
{
basic_block bb;
unsigned int ret = 0;
tree var;
unsigned int i;
/* split the first bb where we can put the forced initializers */
gcc_assert(single_succ_p(ENTRY_BLOCK_PTR_FOR_FN(cfun)));
bb = single_succ(ENTRY_BLOCK_PTR_FOR_FN(cfun));
if (!single_pred_p(bb)) {
split_edge(single_succ_edge(ENTRY_BLOCK_PTR_FOR_FN(cfun)));
gcc_assert(single_succ_p(ENTRY_BLOCK_PTR_FOR_FN(cfun)));
}
/* enumerate all local variables and forcibly initialize our targets */
FOR_EACH_LOCAL_DECL(cfun, i, var) {
tree type = TREE_TYPE(var);
gcc_assert(DECL_P(var));
if (!auto_var_in_fn_p(var, current_function_decl))
continue;
/* only care about structure types */
if (TREE_CODE(type) != RECORD_TYPE && TREE_CODE(type) != UNION_TYPE)
continue;
/* if the type is of interest, examine the variable */
if (TYPE_USERSPACE(type))
initialize(var);
}
return ret;
}
#define PASS_NAME structleak
#define NO_GATE
#define PROPERTIES_REQUIRED PROP_cfg
#define TODO_FLAGS_FINISH TODO_verify_il | TODO_verify_ssa | TODO_verify_stmts | TODO_dump_func | TODO_remove_unused_locals | TODO_update_ssa | TODO_ggc_collect | TODO_verify_flow
#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;
PASS_INFO(structleak, "early_optimizations", 1, PASS_POS_INSERT_BEFORE);
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, "verbose")) {
verbose = true;
continue;
}
error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
}
register_callback(plugin_name, PLUGIN_INFO, NULL, &structleak_plugin_info);
if (enable) {
register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &structleak_pass_info);
register_callback(plugin_name, PLUGIN_FINISH_TYPE, finish_type, NULL);
}
register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL);
return 0;
}