Commit 04fd12df authored by Amery Hung's avatar Amery Hung Committed by Andrii Nakryiko
Browse files

selftests/bpf: Test ambiguous associated struct_ops 



Add a test to make sure implicit struct_ops association does not
break backward compatibility nor return incorrect struct_ops.
struct_ops programs should still be allowed to be reused in
different struct_ops map. The associated struct_ops map set implicitly
however will be poisoned. Trying to read it through the helper
bpf_prog_get_assoc_struct_ops() should result in a NULL pointer.

While recursion of test_1() cannot happen due to the associated
struct_ops being ambiguois, explicitly check for it to prevent stack
overflow if the test regresses.

Signed-off-by: default avatarAmery Hung <ameryhung@gmail.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20251203233748.668365-6-ameryhung@gmail.com
parent 33a165f9

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

+38 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 


#include <test_progs.h>

#include "struct_ops_assoc.skel.h"

#include "struct_ops_assoc_reuse.skel.h"



static void test_st_ops_assoc(void)

{
@@ -65,8 +66,45 @@ static void test_st_ops_assoc(void) 
	struct_ops_assoc__destroy(skel);

}



static void test_st_ops_assoc_reuse(void)

{

	struct struct_ops_assoc_reuse *skel = NULL;

	int err;



	skel = struct_ops_assoc_reuse__open_and_load();

	if (!ASSERT_OK_PTR(skel, "struct_ops_assoc_reuse__open"))

		goto out;



	err = bpf_program__assoc_struct_ops(skel->progs.syscall_prog_a,

					    skel->maps.st_ops_map_a, NULL);

	ASSERT_OK(err, "bpf_program__assoc_struct_ops(syscall_prog_a, st_ops_map_a)");



	err = bpf_program__assoc_struct_ops(skel->progs.syscall_prog_b,

					    skel->maps.st_ops_map_b, NULL);

	ASSERT_OK(err, "bpf_program__assoc_struct_ops(syscall_prog_b, st_ops_map_b)");



	err = struct_ops_assoc_reuse__attach(skel);

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

		goto out;



	/* run syscall_prog that calls .test_1 and checks return */

	err = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.syscall_prog_a), NULL);

	ASSERT_OK(err, "bpf_prog_test_run_opts");



	err = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.syscall_prog_b), NULL);

	ASSERT_OK(err, "bpf_prog_test_run_opts");



	ASSERT_EQ(skel->bss->test_err_a, 0, "skel->bss->test_err_a");

	ASSERT_EQ(skel->bss->test_err_b, 0, "skel->bss->test_err_b");



out:

	struct_ops_assoc_reuse__destroy(skel);

}



void test_struct_ops_assoc(void)

{

	if (test__start_subtest("st_ops_assoc"))

		test_st_ops_assoc();

	if (test__start_subtest("st_ops_assoc_reuse"))

		test_st_ops_assoc_reuse();

}

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

0 → 100644
+75 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0



#include <vmlinux.h>

#include <bpf/bpf_tracing.h>

#include "bpf_misc.h"

#include "../test_kmods/bpf_testmod.h"

#include "../test_kmods/bpf_testmod_kfunc.h"



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



#define MAP_A_MAGIC 1234

int test_err_a;

int recur;



/*

 * test_1_a is reused. The kfunc should not be able to get the associated

 * struct_ops and call test_1 recursively as it is ambiguous.

 */

SEC("struct_ops")

int BPF_PROG(test_1_a, struct st_ops_args *args)

{

	int ret;



	if (!recur) {

		recur++;

		ret = bpf_kfunc_multi_st_ops_test_1_impl(args, NULL);

		if (ret != -1)

			test_err_a++;

		recur--;

	}



	return MAP_A_MAGIC;

}



/* Programs associated with st_ops_map_a */



SEC("syscall")

int syscall_prog_a(void *ctx)

{

	struct st_ops_args args = {};

	int ret;



	ret = bpf_kfunc_multi_st_ops_test_1_impl(&args, NULL);

	if (ret != MAP_A_MAGIC)

		test_err_a++;



	return 0;

}



SEC(".struct_ops.link")

struct bpf_testmod_multi_st_ops st_ops_map_a = {

	.test_1 = (void *)test_1_a,

};



/* Programs associated with st_ops_map_b */



int test_err_b;



SEC("syscall")

int syscall_prog_b(void *ctx)

{

	struct st_ops_args args = {};

	int ret;



	ret = bpf_kfunc_multi_st_ops_test_1_impl(&args, NULL);

	if (ret != MAP_A_MAGIC)

		test_err_b++;



	return 0;

}



SEC(".struct_ops.link")

struct bpf_testmod_multi_st_ops st_ops_map_b = {

	.test_1 = (void *)test_1_a,

};