Commit 7c7b562c authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'gcc-plugin-cleanup-v4.19-rc1' of... 

Merge tag 'gcc-plugin-cleanup-v4.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull gcc plugin cleanups from Kees Cook:

 - Kconfig and Makefile clean-ups (Masahiro Yamada, Kees Cook)

 - gcc-common.h definition clean-ups (Alexander Popov)

* tag 'gcc-plugin-cleanup-v4.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  gcc-plugins: Clean up the cgraph_create_edge* macros
  gcc-plugins: Regularize Makefile.gcc-plugins
  gcc-plugins: split out Kconfig entries to scripts/gcc-plugins/Kconfig
  gcc-plugins: remove unused GCC_PLUGIN_SUBDIR
parents b125d903 45d9a1e3

arch/Kconfig

+2 −144
Original line number Diff line number Diff line
@@ -408,150 +408,6 @@ config SECCOMP_FILTER 


	  See Documentation/userspace-api/seccomp_filter.rst for details.



preferred-plugin-hostcc := $(if-success,[ $(gcc-version) -ge 40800 ],$(HOSTCXX),$(HOSTCC))



config PLUGIN_HOSTCC

	string

	default "$(shell,$(srctree)/scripts/gcc-plugin.sh "$(preferred-plugin-hostcc)" "$(HOSTCXX)" "$(CC)")"

	help

	  Host compiler used to build GCC plugins.  This can be $(HOSTCXX),

	  $(HOSTCC), or a null string if GCC plugin is unsupported.



config HAVE_GCC_PLUGINS

	bool

	help

	  An arch should select this symbol if it supports building with

	  GCC plugins.



menuconfig GCC_PLUGINS

	bool "GCC plugins"

	depends on HAVE_GCC_PLUGINS

	depends on PLUGIN_HOSTCC != ""

	help

	  GCC plugins are loadable modules that provide extra features to the

	  compiler. They are useful for runtime instrumentation and static analysis.



	  See Documentation/gcc-plugins.txt for details.



config GCC_PLUGIN_CYC_COMPLEXITY

	bool "Compute the cyclomatic complexity of a function" if EXPERT

	depends on GCC_PLUGINS

	depends on !COMPILE_TEST	# too noisy

	help

	  The complexity M of a function's control flow graph is defined as:

	   M = E - N + 2P

	  where



	  E = the number of edges

	  N = the number of nodes

	  P = the number of connected components (exit nodes).



	  Enabling this plugin reports the complexity to stderr during the

	  build. It mainly serves as a simple example of how to create a

	  gcc plugin for the kernel.



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 GCC_PLUGIN_LATENT_ENTROPY

	bool "Generate some entropy during boot and runtime"

	depends on GCC_PLUGINS

	help

	  By saying Y here the kernel will instrument some kernel code to

	  extract some entropy from both original and artificially created

	  program state.  This will help especially embedded systems where

	  there is little 'natural' source of entropy normally.  The cost

	  is some slowdown of the boot process (about 0.5%) and fork and

	  irq processing.



	  Note that entropy extracted this way is not cryptographically

	  secure!



	  This plugin was ported from grsecurity/PaX. More information at:

	   * https://grsecurity.net/

	   * https://pax.grsecurity.net/



config GCC_PLUGIN_STRUCTLEAK

	bool "Force initialization of variables containing userspace addresses"

	depends on GCC_PLUGINS

	# Currently STRUCTLEAK inserts initialization out of live scope of

	# variables from KASAN point of view. This leads to KASAN false

	# positive reports. Prohibit this combination for now.

	depends on !KASAN_EXTRA

	help

	  This plugin zero-initializes any structures 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_BYREF_ALL

	bool "Force initialize all struct type variables passed by reference"

	depends on GCC_PLUGIN_STRUCTLEAK

	depends on !COMPILE_TEST

	help

	  Zero initialize any struct type local variable that may be passed by

	  reference without having been initialized.



config GCC_PLUGIN_STRUCTLEAK_VERBOSE

	bool "Report forcefully initialized variables"

	depends on GCC_PLUGIN_STRUCTLEAK

	depends on !COMPILE_TEST	# too noisy

	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 GCC_PLUGIN_RANDSTRUCT

	bool "Randomize layout of sensitive kernel structures"

	depends on GCC_PLUGINS

	select MODVERSIONS if MODULES

	help

	  If you say Y here, the layouts of structures that are entirely

	  function pointers (and have not been manually annotated with

	  __no_randomize_layout), or structures that have been explicitly

	  marked with __randomize_layout, will be randomized at compile-time.

	  This can introduce the requirement of an additional information

	  exposure vulnerability for exploits targeting these structure

	  types.



	  Enabling this feature will introduce some performance impact,

	  slightly increase memory usage, and prevent the use of forensic

	  tools like Volatility against the system (unless the kernel

	  source tree isn't cleaned after kernel installation).



	  The seed used for compilation is located at

	  scripts/gcc-plgins/randomize_layout_seed.h.  It remains after

	  a make clean to allow for external modules to be compiled with

	  the existing seed and will be removed by a make mrproper or

	  make distclean.



	  Note that the implementation requires gcc 4.7 or newer.



	  This plugin was ported from grsecurity/PaX. More information at:

	   * https://grsecurity.net/

	   * https://pax.grsecurity.net/



config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE

	bool "Use cacheline-aware structure randomization"

	depends on GCC_PLUGIN_RANDSTRUCT

	depends on !COMPILE_TEST	# do not reduce test coverage

	help

	  If you say Y here, the RANDSTRUCT randomization will make a

	  best effort at restricting randomization to cacheline-sized

	  groups of elements.  It will further not randomize bitfields

	  in structures.  This reduces the performance hit of RANDSTRUCT

	  at the cost of weakened randomization.



config HAVE_STACKPROTECTOR

	bool

	help
@@ -975,3 +831,5 @@ config REFCOUNT_FULL 
	  security flaw exploits.



source "kernel/gcov/Kconfig"



source "scripts/gcc-plugins/Kconfig"

scripts/Makefile.gcc-plugins

+24 −13
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0



gcc-plugin-$(CONFIG_GCC_PLUGIN_CYC_COMPLEXITY)	+= cyc_complexity_plugin.so



gcc-plugin-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY)	+= latent_entropy_plugin.so

gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY)	+= -DLATENT_ENTROPY_PLUGIN

gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY)		\

		+= -DLATENT_ENTROPY_PLUGIN

ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY

    DISABLE_LATENT_ENTROPY_PLUGIN += -fplugin-arg-latent_entropy_plugin-disable

endif

export DISABLE_LATENT_ENTROPY_PLUGIN



gcc-plugin-$(CONFIG_GCC_PLUGIN_SANCOV)		+= sancov_plugin.so



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_BYREF_ALL)	+= -fplugin-arg-structleak_plugin-byref-all

gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK)	+= -DSTRUCTLEAK_PLUGIN

gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK_VERBOSE)	\

		+= -fplugin-arg-structleak_plugin-verbose

gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL)	\

		+= -fplugin-arg-structleak_plugin-byref-all

gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK)		\

		+= -DSTRUCTLEAK_PLUGIN



gcc-plugin-$(CONFIG_GCC_PLUGIN_RANDSTRUCT)	+= randomize_layout_plugin.so

gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_RANDSTRUCT)	+= -DRANDSTRUCT_PLUGIN

gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_RANDSTRUCT_PERFORMANCE)	+= -fplugin-arg-randomize_layout_plugin-performance-mode

gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_RANDSTRUCT)		\

		+= -DRANDSTRUCT_PLUGIN

gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_RANDSTRUCT_PERFORMANCE)	\

		+= -fplugin-arg-randomize_layout_plugin-performance-mode



# All the plugin CFLAGS are collected here in case a build target needs to

# filter them out of the KBUILD_CFLAGS.

GCC_PLUGINS_CFLAGS := $(strip $(addprefix -fplugin=$(objtree)/scripts/gcc-plugins/, $(gcc-plugin-y)) $(gcc-plugin-cflags-y))



export GCC_PLUGINS_CFLAGS GCC_PLUGIN GCC_PLUGIN_SUBDIR

export DISABLE_LATENT_ENTROPY_PLUGIN



# sancov_plugin.so can be only in CFLAGS_KCOV because avoid duplication.

# The sancov_plugin.so is included via CFLAGS_KCOV, so it is removed here.

GCC_PLUGINS_CFLAGS := $(filter-out %/sancov_plugin.so, $(GCC_PLUGINS_CFLAGS))

export GCC_PLUGINS_CFLAGS



# Add the flags to the build!

KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)



# All enabled GCC plugins are collected here for building below.

GCC_PLUGIN := $(gcc-plugin-y)

GCC_PLUGIN_SUBDIR := $(gcc-plugin-subdir-y)

export GCC_PLUGIN



# Actually do the build, if requested.

PHONY += gcc-plugins

scripts/gcc-plugins/Kconfig

0 → 100644
+142 −0
Original line number Diff line number Diff line 
preferred-plugin-hostcc := $(if-success,[ $(gcc-version) -ge 40800 ],$(HOSTCXX),$(HOSTCC))



config PLUGIN_HOSTCC

	string

	default "$(shell,$(srctree)/scripts/gcc-plugin.sh "$(preferred-plugin-hostcc)" "$(HOSTCXX)" "$(CC)")"

	help

	  Host compiler used to build GCC plugins.  This can be $(HOSTCXX),

	  $(HOSTCC), or a null string if GCC plugin is unsupported.



config HAVE_GCC_PLUGINS

	bool

	help

	  An arch should select this symbol if it supports building with

	  GCC plugins.



menuconfig GCC_PLUGINS

	bool "GCC plugins"

	depends on HAVE_GCC_PLUGINS

	depends on PLUGIN_HOSTCC != ""

	help

	  GCC plugins are loadable modules that provide extra features to the

	  compiler. They are useful for runtime instrumentation and static analysis.



	  See Documentation/gcc-plugins.txt for details.



if GCC_PLUGINS



config GCC_PLUGIN_CYC_COMPLEXITY

	bool "Compute the cyclomatic complexity of a function" if EXPERT

	depends on !COMPILE_TEST	# too noisy

	help

	  The complexity M of a function's control flow graph is defined as:

	   M = E - N + 2P

	  where



	  E = the number of edges

	  N = the number of nodes

	  P = the number of connected components (exit nodes).



	  Enabling this plugin reports the complexity to stderr during the

	  build. It mainly serves as a simple example of how to create a

	  gcc plugin for the kernel.



config GCC_PLUGIN_SANCOV

	bool

	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 GCC_PLUGIN_LATENT_ENTROPY

	bool "Generate some entropy during boot and runtime"

	help

	  By saying Y here the kernel will instrument some kernel code to

	  extract some entropy from both original and artificially created

	  program state.  This will help especially embedded systems where

	  there is little 'natural' source of entropy normally.  The cost

	  is some slowdown of the boot process (about 0.5%) and fork and

	  irq processing.



	  Note that entropy extracted this way is not cryptographically

	  secure!



	  This plugin was ported from grsecurity/PaX. More information at:

	   * https://grsecurity.net/

	   * https://pax.grsecurity.net/



config GCC_PLUGIN_STRUCTLEAK

	bool "Force initialization of variables containing userspace addresses"

	# Currently STRUCTLEAK inserts initialization out of live scope of

	# variables from KASAN point of view. This leads to KASAN false

	# positive reports. Prohibit this combination for now.

	depends on !KASAN_EXTRA

	help

	  This plugin zero-initializes any structures 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_BYREF_ALL

	bool "Force initialize all struct type variables passed by reference"

	depends on GCC_PLUGIN_STRUCTLEAK

	depends on !COMPILE_TEST

	help

	  Zero initialize any struct type local variable that may be passed by

	  reference without having been initialized.



config GCC_PLUGIN_STRUCTLEAK_VERBOSE

	bool "Report forcefully initialized variables"

	depends on GCC_PLUGIN_STRUCTLEAK

	depends on !COMPILE_TEST	# too noisy

	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 GCC_PLUGIN_RANDSTRUCT

	bool "Randomize layout of sensitive kernel structures"

	select MODVERSIONS if MODULES

	help

	  If you say Y here, the layouts of structures that are entirely

	  function pointers (and have not been manually annotated with

	  __no_randomize_layout), or structures that have been explicitly

	  marked with __randomize_layout, will be randomized at compile-time.

	  This can introduce the requirement of an additional information

	  exposure vulnerability for exploits targeting these structure

	  types.



	  Enabling this feature will introduce some performance impact,

	  slightly increase memory usage, and prevent the use of forensic

	  tools like Volatility against the system (unless the kernel

	  source tree isn't cleaned after kernel installation).



	  The seed used for compilation is located at

	  scripts/gcc-plgins/randomize_layout_seed.h.  It remains after

	  a make clean to allow for external modules to be compiled with

	  the existing seed and will be removed by a make mrproper or

	  make distclean.



	  Note that the implementation requires gcc 4.7 or newer.



	  This plugin was ported from grsecurity/PaX. More information at:

	   * https://grsecurity.net/

	   * https://pax.grsecurity.net/



config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE

	bool "Use cacheline-aware structure randomization"

	depends on GCC_PLUGIN_RANDSTRUCT

	depends on !COMPILE_TEST	# do not reduce test coverage

	help

	  If you say Y here, the RANDSTRUCT randomization will make a

	  best effort at restricting randomization to cacheline-sized

	  groups of elements.  It will further not randomize bitfields

	  in structures.  This reduces the performance hit of RANDSTRUCT

	  at the cost of weakened randomization.



endif

scripts/gcc-plugins/Makefile

+0 −5
Original line number Diff line number Diff line
@@ -14,8 +14,6 @@ else 
  export HOST_EXTRACXXFLAGS

endif



export HOSTLIBS



$(obj)/randomize_layout_plugin.o: $(objtree)/$(obj)/randomize_layout_seed.h

quiet_cmd_create_randomize_layout_seed = GENSEED $@

cmd_create_randomize_layout_seed = \
@@ -29,7 +27,4 @@ always := $($(HOSTLIBS)-y) 


$(foreach p,$($(HOSTLIBS)-y:%.so=%),$(eval $(p)-objs := $(p).o))



subdir-y := $(GCC_PLUGIN_SUBDIR)

subdir-  += $(GCC_PLUGIN_SUBDIR)



clean-files += *.so

scripts/gcc-plugins/gcc-common.h

+16 −10
Original line number Diff line number Diff line
@@ -392,13 +392,6 @@ static inline struct cgraph_node *cgraph_alias_target(struct cgraph_node *n) 
}

#endif



#if BUILDING_GCC_VERSION >= 4007 && BUILDING_GCC_VERSION <= 4009

#define cgraph_create_edge(caller, callee, call_stmt, count, freq, nest) \

	cgraph_create_edge((caller), (callee), (call_stmt), (count), (freq))

#define cgraph_create_edge_including_clones(caller, callee, old_call_stmt, call_stmt, count, freq, nest, reason) \

	cgraph_create_edge_including_clones((caller), (callee), (old_call_stmt), (call_stmt), (count), (freq), (reason))

#endif



#if BUILDING_GCC_VERSION <= 4008

#define ENTRY_BLOCK_PTR_FOR_FN(FN)	ENTRY_BLOCK_PTR_FOR_FUNCTION(FN)

#define EXIT_BLOCK_PTR_FOR_FN(FN)	EXIT_BLOCK_PTR_FOR_FUNCTION(FN)
@@ -723,10 +716,23 @@ static inline const char *get_decl_section_name(const_tree decl) 
#define varpool_get_node(decl) varpool_node::get(decl)

#define dump_varpool_node(file, node) (node)->dump(file)



#define cgraph_create_edge(caller, callee, call_stmt, count, freq, nest) \

#if BUILDING_GCC_VERSION >= 8000

#define cgraph_create_edge(caller, callee, call_stmt, count, freq) \

	(caller)->create_edge((callee), (call_stmt), (count))



#define cgraph_create_edge_including_clones(caller, callee,	\

		old_call_stmt, call_stmt, count, freq, reason)	\

	(caller)->create_edge_including_clones((callee),	\

		(old_call_stmt), (call_stmt), (count), (reason))

#else

#define cgraph_create_edge(caller, callee, call_stmt, count, freq) \

	(caller)->create_edge((callee), (call_stmt), (count), (freq))

#define cgraph_create_edge_including_clones(caller, callee, old_call_stmt, call_stmt, count, freq, nest, reason) \

	(caller)->create_edge_including_clones((callee), (old_call_stmt), (call_stmt), (count), (freq), (reason))



#define cgraph_create_edge_including_clones(caller, callee,	\

		old_call_stmt, call_stmt, count, freq, reason)	\

	(caller)->create_edge_including_clones((callee),	\

		(old_call_stmt), (call_stmt), (count), (freq), (reason))

#endif



typedef struct cgraph_node *cgraph_node_ptr;

typedef struct cgraph_edge *cgraph_edge_p;

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