Commit 89ff4089 authored by Eduard Zingerman's avatar Eduard Zingerman Committed by Alexei Starovoitov
Browse files

selftests/bpf: freplace tests for tracking of changes_packet_data 



Try different combinations of global functions replacement:
- replace function that changes packet data with one that doesn't;
- replace function that changes packet data with one that does;
- replace function that doesn't change packet data with one that does;
- replace function that doesn't change packet data with one that doesn't;

Signed-off-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241210041100.1898468-7-eddyz87@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 81f6d053

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

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// SPDX-License-Identifier: GPL-2.0

#include "bpf/libbpf.h"

#include "changes_pkt_data_freplace.skel.h"

#include "changes_pkt_data.skel.h"

#include <test_progs.h>



static void print_verifier_log(const char *log)

{

	if (env.verbosity >= VERBOSE_VERY)

		fprintf(stdout, "VERIFIER LOG:\n=============\n%s=============\n", log);

}



static void test_aux(const char *main_prog_name, const char *freplace_prog_name, bool expect_load)

{

	struct changes_pkt_data_freplace *freplace = NULL;

	struct bpf_program *freplace_prog = NULL;

	LIBBPF_OPTS(bpf_object_open_opts, opts);

	struct changes_pkt_data *main = NULL;

	char log[16*1024];

	int err;



	opts.kernel_log_buf = log;

	opts.kernel_log_size = sizeof(log);

	if (env.verbosity >= VERBOSE_SUPER)

		opts.kernel_log_level = 1 | 2 | 4;

	main = changes_pkt_data__open_opts(&opts);

	if (!ASSERT_OK_PTR(main, "changes_pkt_data__open"))

		goto out;

	err = changes_pkt_data__load(main);

	print_verifier_log(log);

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

		goto out;

	freplace = changes_pkt_data_freplace__open_opts(&opts);

	if (!ASSERT_OK_PTR(freplace, "changes_pkt_data_freplace__open"))

		goto out;

	freplace_prog = bpf_object__find_program_by_name(freplace->obj, freplace_prog_name);

	if (!ASSERT_OK_PTR(freplace_prog, "freplace_prog"))

		goto out;

	bpf_program__set_autoload(freplace_prog, true);

	bpf_program__set_autoattach(freplace_prog, true);

	bpf_program__set_attach_target(freplace_prog,

				       bpf_program__fd(main->progs.dummy),

				       main_prog_name);

	err = changes_pkt_data_freplace__load(freplace);

	print_verifier_log(log);

	if (expect_load) {

		ASSERT_OK(err, "changes_pkt_data_freplace__load");

	} else {

		ASSERT_ERR(err, "changes_pkt_data_freplace__load");

		ASSERT_HAS_SUBSTR(log, "Extension program changes packet data", "error log");

	}



out:

	changes_pkt_data_freplace__destroy(freplace);

	changes_pkt_data__destroy(main);

}



/* There are two global subprograms in both changes_pkt_data.skel.h:

 * - one changes packet data;

 * - another does not.

 * It is ok to freplace subprograms that change packet data with those

 * that either do or do not. It is only ok to freplace subprograms

 * that do not change packet data with those that do not as well.

 * The below tests check outcomes for each combination of such freplace.

 */

void test_changes_pkt_data_freplace(void)

{

	if (test__start_subtest("changes_with_changes"))

		test_aux("changes_pkt_data", "changes_pkt_data", true);

	if (test__start_subtest("changes_with_doesnt_change"))

		test_aux("changes_pkt_data", "does_not_change_pkt_data", true);

	if (test__start_subtest("doesnt_change_with_changes"))

		test_aux("does_not_change_pkt_data", "changes_pkt_data", false);

	if (test__start_subtest("doesnt_change_with_doesnt_change"))

		test_aux("does_not_change_pkt_data", "does_not_change_pkt_data", true);

}

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

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// SPDX-License-Identifier: GPL-2.0



#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>



__noinline

long changes_pkt_data(struct __sk_buff *sk, __u32 len)

{

	return bpf_skb_pull_data(sk, len);

}



__noinline __weak

long does_not_change_pkt_data(struct __sk_buff *sk, __u32 len)

{

	return 0;

}



SEC("tc")

int dummy(struct __sk_buff *sk)

{

	changes_pkt_data(sk, 0);

	does_not_change_pkt_data(sk, 0);

	return 0;

}



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

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

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// SPDX-License-Identifier: GPL-2.0



#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>



SEC("?freplace")

long changes_pkt_data(struct __sk_buff *sk, __u32 len)

{

	return bpf_skb_pull_data(sk, len);

}



SEC("?freplace")

long does_not_change_pkt_data(struct __sk_buff *sk, __u32 len)

{

	return 0;

}



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