Commit 543c37cb authored by Emese Revfy's avatar Emese Revfy Committed by Michal Marek

Add sancov plugin

The sancov gcc plugin inserts a __sanitizer_cov_trace_pc() call
at the start of basic blocks.

This plugin is a helper plugin for the kcov feature. It supports
all gcc versions with plugin support (from gcc-4.5 on).
It is based on the gcc commit "Add fuzzing coverage support" by Dmitry Vyukov
(https://gcc.gnu.org/viewcvs/gcc?limit_changes=0&view=revision&revision=231296).
Signed-off-by: default avatarEmese Revfy <re.emese@gmail.com>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarMichal Marek <mmarek@suse.com>
parent 0dae776c
......@@ -369,7 +369,7 @@ LDFLAGS_MODULE =
CFLAGS_KERNEL =
AFLAGS_KERNEL =
CFLAGS_GCOV = -fprofile-arcs -ftest-coverage -fno-tree-loop-im -Wno-maybe-uninitialized
CFLAGS_KCOV = -fsanitize-coverage=trace-pc
CFLAGS_KCOV := $(call cc-option,-fsanitize-coverage=trace-pc,)
# Use USERINCLUDE when you must reference the UAPI directories only.
......@@ -691,14 +691,6 @@ endif
endif
KBUILD_CFLAGS += $(stackp-flag)
ifdef CONFIG_KCOV
ifeq ($(call cc-option, $(CFLAGS_KCOV)),)
$(warning Cannot use CONFIG_KCOV: \
-fsanitize-coverage=trace-pc is not supported by compiler)
CFLAGS_KCOV =
endif
endif
ifeq ($(cc-name),clang)
KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
......
......@@ -384,6 +384,15 @@ config GCC_PLUGIN_CYC_COMPLEXITY
N = the number of nodes
P = the number of connected components (exit nodes).
config GCC_PLUGIN_SANCOV
bool
depends on GCC_PLUGINS
help
This plugin inserts a __sanitizer_cov_trace_pc() call at the start of
basic blocks. It supports all gcc versions with plugin support (from
gcc-4.5 on). It is based on the commit "Add fuzzing coverage support"
by Dmitry Vyukov <dvyukov@google.com>.
config HAVE_CC_STACKPROTECTOR
bool
help
......
......@@ -8,6 +8,8 @@ PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y))
LDFLAGS_purgatory.ro := -e purgatory_start -r --no-undefined -nostdlib -z nodefaultlib
targets += purgatory.ro
KCOV_INSTRUMENT := n
# Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That
# in turn leaves some undefined symbols like __fentry__ in purgatory and not
# sure how to relocate those. Like kexec-tools, use custom flags.
......
......@@ -708,6 +708,8 @@ config KCOV
bool "Code coverage for fuzzing"
depends on ARCH_HAS_KCOV
select DEBUG_FS
select GCC_PLUGINS
select GCC_PLUGIN_SANCOV
help
KCOV exposes kernel code coverage information in a form suitable
for coverage-guided fuzzing (randomized testing).
......
......@@ -2,10 +2,26 @@ ifdef CONFIG_GCC_PLUGINS
__PLUGINCC := $(call cc-ifversion, -ge, 0408, $(HOSTCXX), $(HOSTCC))
PLUGINCC := $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-plugin.sh "$(__PLUGINCC)" "$(HOSTCXX)" "$(CC)")
SANCOV_PLUGIN := -fplugin=$(objtree)/scripts/gcc-plugins/sancov_plugin.so
gcc-plugin-$(CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) += cyc_complexity_plugin.so
ifdef CONFIG_GCC_PLUGIN_SANCOV
ifeq ($(CFLAGS_KCOV),)
# It is needed because of the gcc-plugin.sh and gcc version checks.
gcc-plugin-$(CONFIG_GCC_PLUGIN_SANCOV) += sancov_plugin.so
ifneq ($(PLUGINCC),)
CFLAGS_KCOV := $(SANCOV_PLUGIN)
else
$(warning warning: cannot use CONFIG_KCOV: -fsanitize-coverage=trace-pc is not supported by compiler)
endif
endif
endif
GCC_PLUGINS_CFLAGS := $(addprefix -fplugin=$(objtree)/scripts/gcc-plugins/, $(gcc-plugin-y))
export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGIN
export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGIN SANCOV_PLUGIN
ifeq ($(PLUGINCC),)
ifneq ($(GCC_PLUGINS_CFLAGS),)
......@@ -16,6 +32,9 @@ ifdef CONFIG_GCC_PLUGINS
$(warning warning: your gcc version does not support plugins, you should upgrade it to gcc 4.5 at least)
endif
endif
else
# SANCOV_PLUGIN can be only in CFLAGS_KCOV because avoid duplication.
GCC_PLUGINS_CFLAGS := $(filter-out $(SANCOV_PLUGIN), $(GCC_PLUGINS_CFLAGS))
endif
KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
......
......@@ -14,8 +14,14 @@ endif
export GCCPLUGINS_DIR HOSTLIBS
ifneq ($(CFLAGS_KCOV), $(SANCOV_PLUGIN))
GCC_PLUGIN := $(filter-out $(SANCOV_PLUGIN), $(GCC_PLUGIN))
endif
$(HOSTLIBS)-y := $(GCC_PLUGIN)
always := $($(HOSTLIBS)-y)
cyc_complexity_plugin-objs := cyc_complexity_plugin.o
sancov_plugin-objs := sancov_plugin.o
clean-files += *.so
/*
* Copyright 2011-2016 by Emese Revfy <re.emese@gmail.com>
* Licensed under the GPL v2, or (at your option) v3
*
* Homepage:
* https://github.com/ephox-gcc-plugins/sancov
*
* This plugin inserts a __sanitizer_cov_trace_pc() call at the start of basic blocks.
* It supports all gcc versions with plugin support (from gcc-4.5 on).
* It is based on the commit "Add fuzzing coverage support" by Dmitry Vyukov <dvyukov@google.com>.
*
* You can read about it more here:
* https://gcc.gnu.org/viewcvs/gcc?limit_changes=0&view=revision&revision=231296
* http://lwn.net/Articles/674854/
* https://github.com/google/syzkaller
* https://lwn.net/Articles/677764/
*
* Usage:
* make run
*/
#include "gcc-common.h"
int plugin_is_GPL_compatible;
tree sancov_fndecl;
static struct plugin_info sancov_plugin_info = {
.version = "20160402",
.help = "sancov plugin\n",
};
static unsigned int sancov_execute(void)
{
basic_block bb;
/* Remove this line when this plugin and kcov will be in the kernel.
if (!strcmp(DECL_NAME_POINTER(current_function_decl), DECL_NAME_POINTER(sancov_fndecl)))
return 0;
*/
FOR_EACH_BB_FN(bb, cfun) {
const_gimple stmt;
gcall *gcall;
gimple_stmt_iterator gsi = gsi_after_labels(bb);
if (gsi_end_p(gsi))
continue;
stmt = gsi_stmt(gsi);
gcall = as_a_gcall(gimple_build_call(sancov_fndecl, 0));
gimple_set_location(gcall, gimple_location(stmt));
gsi_insert_before(&gsi, gcall, GSI_SAME_STMT);
}
return 0;
}
#define PASS_NAME sancov
#define NO_GATE
#define TODO_FLAGS_FINISH TODO_dump_func | TODO_verify_stmts | TODO_update_ssa_no_phi | TODO_verify_flow
#include "gcc-generate-gimple-pass.h"
static void sancov_start_unit(void __unused *gcc_data, void __unused *user_data)
{
tree leaf_attr, nothrow_attr;
tree BT_FN_VOID = build_function_type_list(void_type_node, NULL_TREE);
sancov_fndecl = build_fn_decl("__sanitizer_cov_trace_pc", BT_FN_VOID);
DECL_ASSEMBLER_NAME(sancov_fndecl);
TREE_PUBLIC(sancov_fndecl) = 1;
DECL_EXTERNAL(sancov_fndecl) = 1;
DECL_ARTIFICIAL(sancov_fndecl) = 1;
DECL_PRESERVE_P(sancov_fndecl) = 1;
DECL_UNINLINABLE(sancov_fndecl) = 1;
TREE_USED(sancov_fndecl) = 1;
nothrow_attr = tree_cons(get_identifier("nothrow"), NULL, NULL);
decl_attributes(&sancov_fndecl, nothrow_attr, 0);
gcc_assert(TREE_NOTHROW(sancov_fndecl));
#if BUILDING_GCC_VERSION > 4005
leaf_attr = tree_cons(get_identifier("leaf"), NULL, NULL);
decl_attributes(&sancov_fndecl, leaf_attr, 0);
#endif
}
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;
bool enable = true;
static const struct ggc_root_tab gt_ggc_r_gt_sancov[] = {
{
.base = &sancov_fndecl,
.nelt = 1,
.stride = sizeof(sancov_fndecl),
.cb = &gt_ggc_mx_tree_node,
.pchw = &gt_pch_nx_tree_node
},
LAST_GGC_ROOT_TAB
};
/* 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";
#else
sancov_plugin_pass_info.reference_pass_name = "nrv";
#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"));
return 1;
}
for (i = 0; i < argc; ++i) {
if (!strcmp(argv[i].key, "no-sancov")) {
enable = false;
continue;
}
error(G_("unkown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
}
register_callback(plugin_name, PLUGIN_INFO, NULL, &sancov_plugin_info);
if (!enable)
return 0;
#if BUILDING_GCC_VERSION < 6000
register_callback(plugin_name, PLUGIN_START_UNIT, &sancov_start_unit, NULL);
register_callback(plugin_name, PLUGIN_REGISTER_GGC_ROOTS, NULL, (void *)&gt_ggc_r_gt_sancov);
register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &sancov_plugin_pass_info);
#endif
return 0;
}
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