Commit 830154cd authored by JP Kobryn's avatar JP Kobryn Committed by Alexei Starovoitov
Browse files

bpf/selftests: coverage for bpf_map_ops errors 



These tests expose the issue of being unable to properly check for errors
returned from inlined bpf map helpers that make calls to the bpf_map_ops
functions. At best, a check for zero or non-zero can be done but these
tests show it is not possible to check for a negative value or for a
specific error value.

Signed-off-by: default avatarJP Kobryn <inwardvessel@gmail.com>
Tested-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230322194754.185781-2-inwardvessel@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent d9d93f3b

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

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// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */



#include <errno.h>

#include <sys/syscall.h>

#include <unistd.h>



#include "test_map_ops.skel.h"

#include "test_progs.h"



static void map_update(void)

{

	(void)syscall(__NR_getpid);

}



static void map_delete(void)

{

	(void)syscall(__NR_getppid);

}



static void map_push(void)

{

	(void)syscall(__NR_getuid);

}



static void map_pop(void)

{

	(void)syscall(__NR_geteuid);

}



static void map_peek(void)

{

	(void)syscall(__NR_getgid);

}



static void map_for_each_pass(void)

{

	(void)syscall(__NR_gettid);

}



static void map_for_each_fail(void)

{

	(void)syscall(__NR_getpgid);

}



static int setup(struct test_map_ops **skel)

{

	int err = 0;



	if (!skel)

		return -1;



	*skel = test_map_ops__open();

	if (!ASSERT_OK_PTR(*skel, "test_map_ops__open"))

		return -1;



	(*skel)->rodata->pid = getpid();



	err = test_map_ops__load(*skel);

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

		return err;



	err = test_map_ops__attach(*skel);

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

		return err;



	return err;

}



static void teardown(struct test_map_ops **skel)

{

	if (skel && *skel)

		test_map_ops__destroy(*skel);

}



static void map_ops_update_delete_subtest(void)

{

	struct test_map_ops *skel;



	if (setup(&skel))

		goto teardown;



	map_update();

	ASSERT_OK(skel->bss->err, "map_update_initial");



	map_update();

	ASSERT_LT(skel->bss->err, 0, "map_update_existing");

	ASSERT_EQ(skel->bss->err, -EEXIST, "map_update_existing");



	map_delete();

	ASSERT_OK(skel->bss->err, "map_delete_existing");



	map_delete();

	ASSERT_LT(skel->bss->err, 0, "map_delete_non_existing");

	ASSERT_EQ(skel->bss->err, -ENOENT, "map_delete_non_existing");



teardown:

	teardown(&skel);

}



static void map_ops_push_peek_pop_subtest(void)

{

	struct test_map_ops *skel;



	if (setup(&skel))

		goto teardown;



	map_push();

	ASSERT_OK(skel->bss->err, "map_push_initial");



	map_push();

	ASSERT_LT(skel->bss->err, 0, "map_push_when_full");

	ASSERT_EQ(skel->bss->err, -E2BIG, "map_push_when_full");



	map_peek();

	ASSERT_OK(skel->bss->err, "map_peek");



	map_pop();

	ASSERT_OK(skel->bss->err, "map_pop");



	map_peek();

	ASSERT_LT(skel->bss->err, 0, "map_peek_when_empty");

	ASSERT_EQ(skel->bss->err, -ENOENT, "map_peek_when_empty");



	map_pop();

	ASSERT_LT(skel->bss->err, 0, "map_pop_when_empty");

	ASSERT_EQ(skel->bss->err, -ENOENT, "map_pop_when_empty");



teardown:

	teardown(&skel);

}



static void map_ops_for_each_subtest(void)

{

	struct test_map_ops *skel;



	if (setup(&skel))

		goto teardown;



	map_for_each_pass();

	/* expect to iterate over 1 element */

	ASSERT_EQ(skel->bss->err, 1, "map_for_each_no_flags");



	map_for_each_fail();

	ASSERT_LT(skel->bss->err, 0, "map_for_each_with_flags");

	ASSERT_EQ(skel->bss->err, -EINVAL, "map_for_each_with_flags");



teardown:

	teardown(&skel);

}



void test_map_ops(void)

{

	if (test__start_subtest("map_ops_update_delete"))

		map_ops_update_delete_subtest();



	if (test__start_subtest("map_ops_push_peek_pop"))

		map_ops_push_peek_pop_subtest();



	if (test__start_subtest("map_ops_for_each"))

		map_ops_for_each_subtest();

}

tools/testing/selftests/bpf/progs/test_map_ops.c

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// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */



#include "vmlinux.h"

#include <bpf/bpf_helpers.h>



char _license[] SEC("license") = "GPL";



struct {

	__uint(type, BPF_MAP_TYPE_HASH);

	__uint(max_entries, 1);

	__type(key, int);

	__type(value, int);

} hash_map SEC(".maps");



struct {

	__uint(type, BPF_MAP_TYPE_STACK);

	__uint(max_entries, 1);

	__type(value, int);

} stack_map SEC(".maps");



struct {

	__uint(type, BPF_MAP_TYPE_ARRAY);

	__uint(max_entries, 1);

	__type(key, int);

	__type(value, int);

} array_map SEC(".maps");



const volatile pid_t pid;

long err = 0;



static u64 callback(u64 map, u64 key, u64 val, u64 ctx, u64 flags)

{

	return 0;

}



SEC("tp/syscalls/sys_enter_getpid")

int map_update(void *ctx)

{

	const int key = 0;

	const int val = 1;



	if (pid != (bpf_get_current_pid_tgid() >> 32))

		return 0;



	err = bpf_map_update_elem(&hash_map, &key, &val, BPF_NOEXIST);



	return 0;

}



SEC("tp/syscalls/sys_enter_getppid")

int map_delete(void *ctx)

{

	const int key = 0;



	if (pid != (bpf_get_current_pid_tgid() >> 32))

		return 0;



	err = bpf_map_delete_elem(&hash_map, &key);



	return 0;

}



SEC("tp/syscalls/sys_enter_getuid")

int map_push(void *ctx)

{

	const int val = 1;



	if (pid != (bpf_get_current_pid_tgid() >> 32))

		return 0;



	err = bpf_map_push_elem(&stack_map, &val, 0);



	return 0;

}



SEC("tp/syscalls/sys_enter_geteuid")

int map_pop(void *ctx)

{

	int val;



	if (pid != (bpf_get_current_pid_tgid() >> 32))

		return 0;



	err = bpf_map_pop_elem(&stack_map, &val);



	return 0;

}



SEC("tp/syscalls/sys_enter_getgid")

int map_peek(void *ctx)

{

	int val;



	if (pid != (bpf_get_current_pid_tgid() >> 32))

		return 0;



	err = bpf_map_peek_elem(&stack_map, &val);



	return 0;

}



SEC("tp/syscalls/sys_enter_gettid")

int map_for_each_pass(void *ctx)

{

	const int key = 0;

	const int val = 1;

	const u64 flags = 0;

	int callback_ctx;



	if (pid != (bpf_get_current_pid_tgid() >> 32))

		return 0;



	bpf_map_update_elem(&array_map, &key, &val, flags);



	err = bpf_for_each_map_elem(&array_map, callback, &callback_ctx, flags);



	return 0;

}



SEC("tp/syscalls/sys_enter_getpgid")

int map_for_each_fail(void *ctx)

{

	const int key = 0;

	const int val = 1;

	const u64 flags = BPF_NOEXIST;

	int callback_ctx;



	if (pid != (bpf_get_current_pid_tgid() >> 32))

		return 0;



	bpf_map_update_elem(&array_map, &key, &val, flags);



	/* calling for_each with non-zero flags will return error */

	err = bpf_for_each_map_elem(&array_map, callback, &callback_ctx, flags);



	return 0;

}