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author | 2024-02-22 11:19:40 -0800 | |
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committer | 2024-02-22 12:26:42 -0800 | |
commit | 63c7049ef9d642ab60bb1eccf75b29dc40277664 (patch) | |
tree | 5c5951094ff327b9e52343e25707d5cc944f2fdb | |
parent | bpf: Clarify batch lookup/lookup_and_delete semantics (diff) | |
parent | selftests/bpf: Test case for lacking CFI stub functions. (diff) | |
download | linux-63c7049ef9d642ab60bb1eccf75b29dc40277664.tar.gz linux-63c7049ef9d642ab60bb1eccf75b29dc40277664.tar.bz2 linux-63c7049ef9d642ab60bb1eccf75b29dc40277664.zip |
Merge branch 'Check cfi_stubs before registering a struct_ops type.'
Kui-Feng Lee says:
====================
Recently, st_ops->cfi_stubs was introduced. However, the upcoming new
struct_ops support (e.g. sched_ext) is not aware of this and does not
provide its own cfi_stubs. The kernel ends up NULL dereferencing the
st_ops->cfi_stubs.
Considering struct_ops supports kernel module now, this NULL check
is necessary. This patch set is to reject struct_ops registration
that does not provide a cfi_stubs.
Changes from v4:
- Remove changes of check_member.
- Remove checks of the pointers in cfi_stubs[].
Changes from v3:
- Remove CFI stub function for get_info.
- Allow passing NULL prog arg to check_member of struct
bpf_struct_ops type.
- Call check_member to determines if a CFI stub function should be
defined for an operator.
Changes from v2:
- Add a stub function for get_info of struct tcp_congestion_ops.
Changes from v1:
- Check *(void **)(cfi_stubs + moff) to make sure stub functions are
provided for every operator.
- Add a test case to ensure that struct_ops rejects incomplete
cfi_stub.
v4: https://lore.kernel.org/all/20240221075213.2071454-1-thinker.li@gmail.com/
v3: https://lore.kernel.org/all/20240216193434.735874-1-thinker.li@gmail.com/
v2: https://lore.kernel.org/all/20240216020350.2061373-1-thinker.li@gmail.com/
v1: https://lore.kernel.org/all/20240215022401.1882010-1-thinker.li@gmail.com/
====================
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
-rw-r--r-- | kernel/bpf/bpf_struct_ops.c | 5 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/Makefile | 10 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/bpf_test_no_cfi/Makefile | 19 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/bpf_test_no_cfi/bpf_test_no_cfi.c | 84 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/prog_tests/test_struct_ops_no_cfi.c | 35 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/testing_helpers.c | 4 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/testing_helpers.h | 2 |
7 files changed, 156 insertions, 3 deletions
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index 0d7be97a2411..a6019087b467 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -302,6 +302,11 @@ int bpf_struct_ops_desc_init(struct bpf_struct_ops_desc *st_ops_desc, } sprintf(value_name, "%s%s", VALUE_PREFIX, st_ops->name); + if (!st_ops->cfi_stubs) { + pr_warn("struct_ops for %s has no cfi_stubs\n", st_ops->name); + return -EINVAL; + } + type_id = btf_find_by_name_kind(btf, st_ops->name, BTF_KIND_STRUCT); if (type_id < 0) { diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 9be69ff701ba..84cb5500e8ef 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -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 diff --git a/tools/testing/selftests/bpf/bpf_test_no_cfi/Makefile b/tools/testing/selftests/bpf/bpf_test_no_cfi/Makefile new file mode 100644 index 000000000000..ed5143b79edf --- /dev/null +++ b/tools/testing/selftests/bpf/bpf_test_no_cfi/Makefile @@ -0,0 +1,19 @@ +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 + diff --git a/tools/testing/selftests/bpf/bpf_test_no_cfi/bpf_test_no_cfi.c b/tools/testing/selftests/bpf/bpf_test_no_cfi/bpf_test_no_cfi.c new file mode 100644 index 000000000000..b1dd889d5d7d --- /dev/null +++ b/tools/testing/selftests/bpf/bpf_test_no_cfi/bpf_test_no_cfi.c @@ -0,0 +1,84 @@ +// 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"); + diff --git a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_no_cfi.c b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_no_cfi.c new file mode 100644 index 000000000000..106ea447965a --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_no_cfi.c @@ -0,0 +1,35 @@ +// 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(); +} diff --git a/tools/testing/selftests/bpf/testing_helpers.c b/tools/testing/selftests/bpf/testing_helpers.c index a59e56d804ee..28b6646662af 100644 --- a/tools/testing/selftests/bpf/testing_helpers.c +++ b/tools/testing/selftests/bpf/testing_helpers.c @@ -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); } diff --git a/tools/testing/selftests/bpf/testing_helpers.h b/tools/testing/selftests/bpf/testing_helpers.h index d14de81727e6..d55f6ab12433 100644 --- a/tools/testing/selftests/bpf/testing_helpers.h +++ b/tools/testing/selftests/bpf/testing_helpers.h @@ -36,6 +36,8 @@ __u64 read_perf_max_sample_freq(void); int load_bpf_testmod(bool verbose); int unload_bpf_testmod(bool verbose); int kern_sync_rcu(void); +int finit_module(int fd, const char *param_values, int flags); +int delete_module(const char *name, int flags); static inline __u64 get_time_ns(void) { |