Re: [PATCH bpf-next v4 2/2] selftests: bpf: test BPF_PROG_QUERY for progs attached to sockmap

[Yonghong Song <yhs@fb.com>]

On 11/2/21 1:48 AM, Di Zhu wrote:
> Add test for querying progs attached to sockmap. we use an existing
> libbpf query interface to query prog cnt before and after progs
> attaching to sockmap and check whether the queried prog id is right.
> 
> Signed-off-by: Di Zhu <zhudi2@huawei.com>
> ---
>   .../selftests/bpf/prog_tests/sockmap_basic.c  | 84 +++++++++++++++++++
>   .../bpf/progs/test_sockmap_progs_query.c      | 24 ++++++
>   2 files changed, 108 insertions(+)
>   create mode 100644 tools/testing/selftests/bpf/progs/test_sockmap_progs_query.c
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> index 1352ec104149..7f3d5c5da6e1 100644
> --- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> @@ -8,6 +8,7 @@
>   #include "test_sockmap_update.skel.h"
>   #include "test_sockmap_invalid_update.skel.h"
>   #include "test_sockmap_skb_verdict_attach.skel.h"
> +#include "test_sockmap_progs_query.skel.h"
>   #include "bpf_iter_sockmap.skel.h"
>   
>   #define TCP_REPAIR		19	/* TCP sock is under repair right now */
> @@ -315,6 +316,83 @@ static void test_sockmap_skb_verdict_attach(enum bpf_attach_type first,
>   	test_sockmap_skb_verdict_attach__destroy(skel);
>   }
>   
> +static __u32 query_prog_id(int prog)

Let us use name "prog_fd" to be clear it is a fd.

> +{
> +	struct bpf_prog_info info = {};
> +	__u32 info_len = sizeof(info);
> +	int err;
> +
> +	err = bpf_obj_get_info_by_fd(prog, &info, &info_len);
> +	if (CHECK_FAIL(err || info_len != sizeof(info))) {
> +		perror("bpf_obj_get_info_by_fd");
> +		return 0;
> +	}
> +
> +	return info.id;
> +}
> +
> +static void test_sockmap_progs_query(enum bpf_attach_type attach_type)
> +{
> +	struct test_sockmap_progs_query *skel;
> +	int err, map, verdict, duration = 0;

Let us use map_fd, verdict_fd.

> +	__u32 attach_flags = 0;
> +	__u32 prog_ids[3] = {};
> +	__u32 prog_cnt = 3;
> +
> +	skel = test_sockmap_progs_query__open_and_load();
> +	if (CHECK_FAIL(!skel)) {

Please user ASSERT_* macros. You can check other prog_tests/... files.

> +		perror("test_sockmap_progs_query__open_and_load");

No need to have the above perror if you use
	if (!ASSERT_OK_PTR(skel, "..."))

> +		return;
> +	}
> +
> +	map = bpf_map__fd(skel->maps.sock_map);
> +
> +	if (attach_type == BPF_SK_MSG_VERDICT)
> +		verdict = bpf_program__fd(skel->progs.prog_skmsg_verdict);
> +	else
> +		verdict = bpf_program__fd(skel->progs.prog_skb_verdict);
> +
> +	err = bpf_prog_query(map, attach_type, 0 /* query flags */,
> +			     &attach_flags, prog_ids, &prog_cnt);
> +	if (CHECK(err, "bpf_prog_query", "failed\n"))
> +		goto out;
> +
> +	if (CHECK(attach_flags != 0, "bpf_prog_query",
> +		  "wrong attach_flags on query: %u", attach_flags))
> +		goto out;
> +
> +	if (CHECK(prog_cnt != 0, "bpf_prog_query",
> +		  "wrong program count on query: %u", prog_cnt))
> +		goto out;
> +
> +	err = bpf_prog_attach(verdict, map, attach_type, 0);
> +	if (CHECK(err, "bpf_prog_attach", "failed\n"))
> +		goto out;
> +
> +	prog_cnt = 1;
> +	err = bpf_prog_query(map, attach_type, 0 /* query flags */,
> +			     &attach_flags, prog_ids, &prog_cnt);
> +	if (CHECK(err, "bpf_prog_query", "failed\n"))
> +		goto detach;
> +
> +	if (CHECK(attach_flags != 0, "bpf_prog_query attach_flags",
> +		  "wrong attach_flags on query: %u", attach_flags))
> +		goto detach;
> +
> +	if (CHECK(prog_cnt != 1, "bpf_prog_query prog_cnt",
> +		  "wrong program count on query: %u", prog_cnt))
> +		goto detach;
> +
> +	if (CHECK(prog_ids[0] != query_prog_id(verdict), "bpf_prog_query",
> +		  "wrong prog_ids on query: %u", prog_ids[0]))
> +		goto detach;

For the above four checks, you can check all of them instead of
goto detach if one of them failed. This gives better initial coverage.

> +
> +detach:
> +	bpf_prog_detach2(verdict, map, attach_type);
> +out:
> +	test_sockmap_progs_query__destroy(skel);
> +}
> +
>   void test_sockmap_basic(void)
>   {
>   	if (test__start_subtest("sockmap create_update_free"))
> @@ -341,4 +419,10 @@ void test_sockmap_basic(void)
>   		test_sockmap_skb_verdict_attach(BPF_SK_SKB_STREAM_VERDICT,
>   						BPF_SK_SKB_VERDICT);
>   	}
> +	if (test__start_subtest("sockmap progs query")) {
> +		test_sockmap_progs_query(BPF_SK_MSG_VERDICT);
> +		test_sockmap_progs_query(BPF_SK_SKB_STREAM_PARSER);
> +		test_sockmap_progs_query(BPF_SK_SKB_STREAM_VERDICT);
> +		test_sockmap_progs_query(BPF_SK_SKB_VERDICT);
> +	}
>   }
> diff --git a/tools/testing/selftests/bpf/progs/test_sockmap_progs_query.c b/tools/testing/selftests/bpf/progs/test_sockmap_progs_query.c
> new file mode 100644
> index 000000000000..9d58d61c0dee
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_sockmap_progs_query.c
> @@ -0,0 +1,24 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include "vmlinux.h"
> +#include <bpf/bpf_helpers.h>
> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_SOCKMAP);
> +	__uint(max_entries, 1);
> +	__type(key, __u32);
> +	__type(value, __u64);
> +} sock_map SEC(".maps");
> +
> +SEC("sk_skb")
> +int prog_skb_verdict(struct __sk_buff *skb)
> +{
> +	return SK_PASS;
> +}
> +
> +SEC("sk_msg")
> +int prog_skmsg_verdict(struct sk_msg_md *msg)
> +{
> +	return SK_PASS;
> +}
> +
> +char _license[] SEC("license") = "GPL";
>