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selftests/bpf: Test ambiguous associated struct_ops

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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: Amery Hung <ameryhung@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20251203233748.668365-6-ameryhung@gmail.com
This commit is contained in:
Amery Hung
2025-12-03 15:37:47 -08:00
committed by Andrii Nakryiko
parent 33a165f9c2
commit 04fd12df4e
2 changed files with 113 additions and 0 deletions
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38
tools/testing/selftests/bpf/prog_tests/test_struct_ops_assoc.c
View File

@@ -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();
}

75
tools/testing/selftests/bpf/progs/struct_ops_assoc_reuse.c Normal file
View File

@@ -0,0 +1,75 @@
// 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,
};