Commit e9bbda13 authored by Kui-Feng Lee's avatar Kui-Feng Lee Committed by Martin KaFai Lau
Browse files

selftests/bpf: Test case for lacking CFI stub functions. 



Ensure struct_ops rejects the registration of struct_ops types without
proper CFI stub functions.

bpf_test_no_cfi.ko is a module that attempts to register a struct_ops type
called "bpf_test_no_cfi_ops" with cfi_stubs of NULL and non-NULL value.
The NULL one should fail, and the non-NULL one should succeed. The module
can only be loaded successfully if these registrations yield the expected
results.

Signed-off-by: default avatarKui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240222021105.1180475-3-thinker.li@gmail.com


Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
parent 3e000833

tools/testing/selftests/bpf/Makefile

+9 −1
Original line number Diff line number Diff line
@@ -132,7 +132,7 @@ TEST_GEN_PROGS_EXTENDED = test_sock_addr test_skb_cgroup_id_user \ 
	flow_dissector_load test_flow_dissector test_tcp_check_syncookie_user \

	test_lirc_mode2_user xdping test_cpp runqslower bench bpf_testmod.ko \

	xskxceiver xdp_redirect_multi xdp_synproxy veristat xdp_hw_metadata \

	xdp_features

	xdp_features bpf_test_no_cfi.ko



TEST_GEN_FILES += liburandom_read.so urandom_read sign-file uprobe_multi
@@ -254,6 +254,12 @@ $(OUTPUT)/bpf_testmod.ko: $(VMLINUX_BTF) $(RESOLVE_BTFIDS) $(wildcard bpf_testmo 
	$(Q)$(MAKE) $(submake_extras) RESOLVE_BTFIDS=$(RESOLVE_BTFIDS) -C bpf_testmod

	$(Q)cp bpf_testmod/bpf_testmod.ko $@



$(OUTPUT)/bpf_test_no_cfi.ko: $(VMLINUX_BTF) $(RESOLVE_BTFIDS) $(wildcard bpf_test_no_cfi/Makefile bpf_test_no_cfi/*.[ch])

	$(call msg,MOD,,$@)

	$(Q)$(RM) bpf_test_no_cfi/bpf_test_no_cfi.ko # force re-compilation

	$(Q)$(MAKE) $(submake_extras) RESOLVE_BTFIDS=$(RESOLVE_BTFIDS) -C bpf_test_no_cfi

	$(Q)cp bpf_test_no_cfi/bpf_test_no_cfi.ko $@



DEFAULT_BPFTOOL := $(HOST_SCRATCH_DIR)/sbin/bpftool

ifneq ($(CROSS_COMPILE),)

CROSS_BPFTOOL := $(SCRATCH_DIR)/sbin/bpftool
@@ -631,6 +637,7 @@ TRUNNER_EXTRA_SOURCES := test_progs.c \ 
			 flow_dissector_load.h	\

			 ip_check_defrag_frags.h

TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read $(OUTPUT)/bpf_testmod.ko	\

		       $(OUTPUT)/bpf_test_no_cfi.ko			\

		       $(OUTPUT)/liburandom_read.so			\

		       $(OUTPUT)/xdp_synproxy				\

		       $(OUTPUT)/sign-file				\
@@ -759,6 +766,7 @@ EXTRA_CLEAN := $(SCRATCH_DIR) $(HOST_SCRATCH_DIR) \ 
	feature bpftool							\

	$(addprefix $(OUTPUT)/,*.o *.skel.h *.lskel.h *.subskel.h	\

			       no_alu32 cpuv4 bpf_gcc bpf_testmod.ko	\

			       bpf_test_no_cfi.ko			\

			       liburandom_read.so)



.PHONY: docs docs-clean

tools/testing/selftests/bpf/bpf_test_no_cfi/Makefile

0 → 100644
+19 −0
Original line number Diff line number Diff line 
BPF_TEST_NO_CFI_DIR := $(realpath $(dir $(abspath $(lastword $(MAKEFILE_LIST)))))

KDIR ?= $(abspath $(BPF_TEST_NO_CFI_DIR)/../../../../..)



ifeq ($(V),1)

Q =

else

Q = @

endif



MODULES = bpf_test_no_cfi.ko



obj-m += bpf_test_no_cfi.o



all:

	+$(Q)make -C $(KDIR) M=$(BPF_TEST_NO_CFI_DIR) modules



clean:

	+$(Q)make -C $(KDIR) M=$(BPF_TEST_NO_CFI_DIR) clean

tools/testing/selftests/bpf/bpf_test_no_cfi/bpf_test_no_cfi.c

0 → 100644
+84 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */

#include <linux/bpf.h>

#include <linux/btf.h>

#include <linux/init.h>

#include <linux/module.h>



struct bpf_test_no_cfi_ops {

	void (*fn_1)(void);

	void (*fn_2)(void);

};



static int dummy_init(struct btf *btf)

{

	return 0;

}



static int dummy_init_member(const struct btf_type *t,

			     const struct btf_member *member,

			     void *kdata, const void *udata)

{

	return 0;

}



static int dummy_reg(void *kdata)

{

	return 0;

}



static void dummy_unreg(void *kdata)

{

}



static const struct bpf_verifier_ops dummy_verifier_ops;



static void bpf_test_no_cfi_ops__fn_1(void)

{

}



static void bpf_test_no_cfi_ops__fn_2(void)

{

}



static struct bpf_test_no_cfi_ops __test_no_cif_ops = {

	.fn_1 = bpf_test_no_cfi_ops__fn_1,

	.fn_2 = bpf_test_no_cfi_ops__fn_2,

};



static struct bpf_struct_ops test_no_cif_ops = {

	.verifier_ops = &dummy_verifier_ops,

	.init = dummy_init,

	.init_member = dummy_init_member,

	.reg = dummy_reg,

	.unreg = dummy_unreg,

	.name = "bpf_test_no_cfi_ops",

	.owner = THIS_MODULE,

};



static int bpf_test_no_cfi_init(void)

{

	int ret;



	ret = register_bpf_struct_ops(&test_no_cif_ops,

				      bpf_test_no_cfi_ops);

	if (!ret)

		return -EINVAL;



	test_no_cif_ops.cfi_stubs = &__test_no_cif_ops;

	ret = register_bpf_struct_ops(&test_no_cif_ops,

				      bpf_test_no_cfi_ops);

	return ret;

}



static void bpf_test_no_cfi_exit(void)

{

}



module_init(bpf_test_no_cfi_init);

module_exit(bpf_test_no_cfi_exit);



MODULE_AUTHOR("Kuifeng Lee");

MODULE_DESCRIPTION("BPF no cfi_stubs test module");

MODULE_LICENSE("Dual BSD/GPL");

tools/testing/selftests/bpf/prog_tests/test_struct_ops_no_cfi.c

0 → 100644
+35 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */

#include <test_progs.h>

#include <testing_helpers.h>



static void load_bpf_test_no_cfi(void)

{

	int fd;

	int err;



	fd = open("bpf_test_no_cfi.ko", O_RDONLY);

	if (!ASSERT_GE(fd, 0, "open"))

		return;



	/* The module will try to register a struct_ops type without

	 * cfi_stubs and with cfi_stubs.

	 *

	 * The one without cfi_stub should fail. The module will be loaded

	 * successfully only if the result of the registration is as

	 * expected, or it fails.

	 */

	err = finit_module(fd, "", 0);

	close(fd);

	if (!ASSERT_OK(err, "finit_module"))

		return;



	err = delete_module("bpf_test_no_cfi", 0);

	ASSERT_OK(err, "delete_module");

}



void test_struct_ops_no_cfi(void)

{

	if (test__start_subtest("load_bpf_test_no_cfi"))

		load_bpf_test_no_cfi();

}

tools/testing/selftests/bpf/testing_helpers.c

+2 −2
Original line number Diff line number Diff line
@@ -356,12 +356,12 @@ __u64 read_perf_max_sample_freq(void) 
	return sample_freq;

}



static int finit_module(int fd, const char *param_values, int flags)

int finit_module(int fd, const char *param_values, int flags)

{

	return syscall(__NR_finit_module, fd, param_values, flags);

}



static int delete_module(const char *name, int flags)

int delete_module(const char *name, int flags)

{

	return syscall(__NR_delete_module, name, flags);

}