Commit bd6fecb9 authored by YiFei Zhu's avatar YiFei Zhu Committed by Daniel Borkmann
Browse files

selftests/bpf: Add cgroup_skb/egress test for load_bytes_relative 



When cgroup_skb/egress triggers the MAC header is not set. Added a
test that asserts reading MAC header is a -EFAULT but NET header
succeeds. The test result from within the eBPF program is stored in
an 1-element array map that the userspace then reads and asserts on.

Another assertion is added that reading from a large offset, past
the end of packet, returns -EFAULT.

Signed-off-by: default avatarYiFei Zhu <zhuyifei@google.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: default avatarStanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/9028ccbea4385a620e69c0a104f469ffd655c01e.1591812755.git.zhuyifei@google.com
parent 0f5d82f1

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

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+71 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only



/*

 * Copyright 2020 Google LLC.

 */



#include <test_progs.h>

#include <network_helpers.h>



void test_load_bytes_relative(void)

{

	int server_fd, cgroup_fd, prog_fd, map_fd, client_fd;

	int err;

	struct bpf_object *obj;

	struct bpf_program *prog;

	struct bpf_map *test_result;

	__u32 duration = 0;



	__u32 map_key = 0;

	__u32 map_value = 0;



	cgroup_fd = test__join_cgroup("/load_bytes_relative");

	if (CHECK_FAIL(cgroup_fd < 0))

		return;



	server_fd = start_server(AF_INET, SOCK_STREAM);

	if (CHECK_FAIL(server_fd < 0))

		goto close_cgroup_fd;



	err = bpf_prog_load("./load_bytes_relative.o", BPF_PROG_TYPE_CGROUP_SKB,

			    &obj, &prog_fd);

	if (CHECK_FAIL(err))

		goto close_server_fd;



	test_result = bpf_object__find_map_by_name(obj, "test_result");

	if (CHECK_FAIL(!test_result))

		goto close_bpf_object;



	map_fd = bpf_map__fd(test_result);

	if (map_fd < 0)

		goto close_bpf_object;



	prog = bpf_object__find_program_by_name(obj, "load_bytes_relative");

	if (CHECK_FAIL(!prog))

		goto close_bpf_object;



	err = bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_INET_EGRESS,

			      BPF_F_ALLOW_MULTI);

	if (CHECK_FAIL(err))

		goto close_bpf_object;



	client_fd = connect_to_fd(AF_INET, SOCK_STREAM, server_fd);

	if (CHECK_FAIL(client_fd < 0))

		goto close_bpf_object;

	close(client_fd);



	err = bpf_map_lookup_elem(map_fd, &map_key, &map_value);

	if (CHECK_FAIL(err))

		goto close_bpf_object;



	CHECK(map_value != 1, "bpf", "bpf program returned failure");



close_bpf_object:

	bpf_object__close(obj);



close_server_fd:

	close(server_fd);



close_cgroup_fd:

	close(cgroup_fd);

}

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

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Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only



/*

 * Copyright 2020 Google LLC.

 */



#include <errno.h>

#include <linux/bpf.h>

#include <linux/if_ether.h>

#include <linux/ip.h>

#include <bpf/bpf_helpers.h>



struct {

	__uint(type, BPF_MAP_TYPE_ARRAY);

	__uint(max_entries, 1);

	__type(key, __u32);

	__type(value, __u32);

} test_result SEC(".maps");



SEC("cgroup_skb/egress")

int load_bytes_relative(struct __sk_buff *skb)

{

	struct ethhdr eth;

	struct iphdr iph;



	__u32 map_key = 0;

	__u32 test_passed = 0;



	/* MAC header is not set by the time cgroup_skb/egress triggers */

	if (bpf_skb_load_bytes_relative(skb, 0, &eth, sizeof(eth),

					BPF_HDR_START_MAC) != -EFAULT)

		goto fail;



	if (bpf_skb_load_bytes_relative(skb, 0, &iph, sizeof(iph),

					BPF_HDR_START_NET))

		goto fail;



	if (bpf_skb_load_bytes_relative(skb, 0xffff, &iph, sizeof(iph),

					BPF_HDR_START_NET) != -EFAULT)

		goto fail;



	test_passed = 1;



fail:

	bpf_map_update_elem(&test_result, &map_key, &test_passed, BPF_ANY);



	return 1;

}

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