On Tue, Feb 27, 2024 at 10:45:53PM +0200, Eduard Zingerman wrote:
> When loading struct_ops programs kernel requires BTF id of the
> struct_ops type and member index for attachment point inside that
> type. This makes it not possible to have same BPF program used in
> struct_ops maps that have different struct_ops type.
> Check if libbpf rejects such BPF objects files.
>
> Signed-off-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
> ---
> .../selftests/bpf/bpf_testmod/bpf_testmod.c | 24 +++++++++++
> .../selftests/bpf/bpf_testmod/bpf_testmod.h | 4 ++
> .../selftests/bpf/prog_tests/bad_struct_ops.c | 42 +++++++++++++++++++
> .../selftests/bpf/progs/bad_struct_ops.c | 17 ++++++++
> 4 files changed, 87 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/prog_tests/bad_struct_ops.c
> create mode 100644 tools/testing/selftests/bpf/progs/bad_struct_ops.c
>
> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> index 0d8437e05f64..69f5eb9ad546 100644
> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
> @@ -601,6 +601,29 @@ struct bpf_struct_ops bpf_bpf_testmod_ops = {
> .owner = THIS_MODULE,
> };
>
> +static int bpf_dummy_reg2(void *kdata)
> +{
> + struct bpf_testmod_ops2 *ops = kdata;
> +
> + ops->test_1();
> + return 0;
> +}
> +
> +static struct bpf_testmod_ops2 __bpf_testmod_ops2 = {
> + .test_1 = bpf_testmod_test_1,
> +};
> +
> +struct bpf_struct_ops bpf_testmod_ops2 = {
> + .verifier_ops = &bpf_testmod_verifier_ops,
> + .init = bpf_testmod_ops_init,
> + .init_member = bpf_testmod_ops_init_member,
> + .reg = bpf_dummy_reg2,
> + .unreg = bpf_dummy_unreg,
> + .cfi_stubs = &__bpf_testmod_ops2,
> + .name = "bpf_testmod_ops2",
> + .owner = THIS_MODULE,
> +};
> +
> extern int bpf_fentry_test1(int a);
>
> static int bpf_testmod_init(void)
> @@ -612,6 +635,7 @@ static int bpf_testmod_init(void)
> ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_testmod_kfunc_set);
> ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &bpf_testmod_kfunc_set);
> ret = ret ?: register_bpf_struct_ops(&bpf_bpf_testmod_ops, bpf_testmod_ops);
> + ret = ret ?: register_bpf_struct_ops(&bpf_testmod_ops2, bpf_testmod_ops2);
> if (ret < 0)
> return ret;
> if (bpf_fentry_test1(0) < 0)
> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
> index c3b0cf788f9f..3183fff7f246 100644
> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
> @@ -37,4 +37,8 @@ struct bpf_testmod_ops {
> int (*test_maybe_null)(int dummy, struct task_struct *task);
> };
>
> +struct bpf_testmod_ops2 {
> + int (*test_1)(void);
> +};
> +
> #endif /* _BPF_TESTMOD_H */
> diff --git a/tools/testing/selftests/bpf/prog_tests/bad_struct_ops.c b/tools/testing/selftests/bpf/prog_tests/bad_struct_ops.c
> new file mode 100644
> index 000000000000..9c689db4b05b
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/bad_struct_ops.c
> @@ -0,0 +1,42 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <test_progs.h>
> +#include "bad_struct_ops.skel.h"
> +
> +#define EXPECTED_MSG "libbpf: struct_ops reloc"
> +
> +static libbpf_print_fn_t old_print_cb;
> +static bool msg_found;
> +
> +static int print_cb(enum libbpf_print_level level, const char *fmt, va_list args)
> +{
> + old_print_cb(level, fmt, args);
> + if (level == LIBBPF_WARN && strncmp(fmt, EXPECTED_MSG, strlen(EXPECTED_MSG)) == 0)
> + msg_found = true;
> +
> + return 0;
> +}
Not necessary at all for this patch set / just an observation, but it would be
nice to have this be something offered by the core prog_tests framework
(meaning, the ability to assert libbpf output for a testcase).
> +
> +static void test_bad_struct_ops(void)
> +{
> + struct bad_struct_ops *skel;
> + int err;
> +
> + old_print_cb = libbpf_set_print(print_cb);
> + skel = bad_struct_ops__open_and_load();
> + err = errno;
> + libbpf_set_print(old_print_cb);
> + if (!ASSERT_NULL(skel, "bad_struct_ops__open_and_load"))
> + return;
> +
> + ASSERT_EQ(err, EINVAL, "errno should be EINVAL");
> + ASSERT_TRUE(msg_found, "expected message");
> +
> + bad_struct_ops__destroy(skel);
> +}
> +
> +void serial_test_bad_struct_ops(void)
> +{
> + if (test__start_subtest("test_bad_struct_ops"))
> + test_bad_struct_ops();
> +}
> diff --git a/tools/testing/selftests/bpf/progs/bad_struct_ops.c b/tools/testing/selftests/bpf/progs/bad_struct_ops.c
> new file mode 100644
> index 000000000000..9c103afbfdb1
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/bad_struct_ops.c
> @@ -0,0 +1,17 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <vmlinux.h>
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +#include "../bpf_testmod/bpf_testmod.h"
> +
> +char _license[] SEC("license") = "GPL";
> +
> +SEC("struct_ops/test_1")
> +int BPF_PROG(test_1) { return 0; }
> +
> +SEC(".struct_ops.link")
> +struct bpf_testmod_ops testmod_1 = { .test_1 = (void *)test_1 };
Just to make be 100% sure that we're isolating the issue under test, should we
also add a .test_2 prog and add it to the struct bpf_testmod_ops map?
> +
> +SEC(".struct_ops.link")
> +struct bpf_testmod_ops2 testmod_2 = { .test_1 = (void *)test_1 };
> --
> 2.43.0
>
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