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Subject: Re: [PATCH bpf-next 6/6] selftests: bpf: test sockmap update from BPF
To:     Lorenz Bauer <lmb@cloudflare.com>, <jakub@cloudflare.com>,
        <john.fastabend@gmail.com>, Shuah Khan <shuah@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>
CC:     <kernel-team@cloudflare.com>, <linux-kernel@vger.kernel.org>,
        <linux-kselftest@vger.kernel.org>, <netdev@vger.kernel.org>,
        <bpf@vger.kernel.org>
References: <20200819092436.58232-1-lmb@cloudflare.com>
 <20200819092436.58232-7-lmb@cloudflare.com>
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On 8/19/20 2:24 AM, Lorenz Bauer wrote:
> Add a test which copies a socket from a sockmap into another sockmap
> or sockhash. This excercises bpf_map_update_elem support from BPF
> context. Compare the socket cookies from source and destination to
> ensure that the copy succeeded.
> 
> Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
> ---
>   .../selftests/bpf/prog_tests/sockmap_basic.c  | 76 +++++++++++++++++++
>   .../selftests/bpf/progs/test_sockmap_copy.c   | 48 ++++++++++++
>   2 files changed, 124 insertions(+)
>   create mode 100644 tools/testing/selftests/bpf/progs/test_sockmap_copy.c
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> index 96e7b7f84c65..d30cabc00e9e 100644
> --- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> @@ -4,6 +4,7 @@
>   
>   #include "test_progs.h"
>   #include "test_skmsg_load_helpers.skel.h"
> +#include "test_sockmap_copy.skel.h"
>   
>   #define TCP_REPAIR		19	/* TCP sock is under repair right now */
>   
> @@ -101,6 +102,77 @@ static void test_skmsg_helpers(enum bpf_map_type map_type)
>   	test_skmsg_load_helpers__destroy(skel);
>   }
>   
> +static void test_sockmap_copy(enum bpf_map_type map_type)
> +{
> +	struct bpf_prog_test_run_attr attr;
> +	struct test_sockmap_copy *skel;
> +	__u64 src_cookie, dst_cookie;
> +	int err, prog, s, src, dst;
> +	const __u32 zero = 0;
> +	char dummy[14] = {0};
> +
> +	s = connected_socket_v4();

Maybe change variable name to "sk" for better clarity?

> +	if (CHECK_FAIL(s == -1))
> +		return;
> +
> +	skel = test_sockmap_copy__open_and_load();
> +	if (CHECK_FAIL(!skel)) {
> +		close(s);
> +		perror("test_sockmap_copy__open_and_load");
> +		return;
> +	}

Could you use CHECK instead of CHECK_FAIL?
With CHECK, you can print additional information without perror.


> +
> +	prog = bpf_program__fd(skel->progs.copy_sock_map);
> +	src = bpf_map__fd(skel->maps.src);
> +	if (map_type == BPF_MAP_TYPE_SOCKMAP)
> +		dst = bpf_map__fd(skel->maps.dst_sock_map);
> +	else
> +		dst = bpf_map__fd(skel->maps.dst_sock_hash);
> +
> +	err = bpf_map_update_elem(src, &zero, &s, BPF_NOEXIST);

The map defined in bpf program is __u64 and here "s" is int.
Any potential issues?

> +	if (CHECK_FAIL(err)) {
> +		perror("bpf_map_update");
> +		goto out;
> +	}
> +
> +	err = bpf_map_lookup_elem(src, &zero, &src_cookie);
> +	if (CHECK_FAIL(err)) {
> +		perror("bpf_map_lookup_elem(src)");
> +		goto out;
> +	}
> +
> +	attr = (struct bpf_prog_test_run_attr){
> +		.prog_fd = prog,
> +		.repeat = 1,
> +		.data_in = dummy,
> +		.data_size_in = sizeof(dummy),
> +	};
> +
> +	err = bpf_prog_test_run_xattr(&attr);
> +	if (err) {

You can use CHECK macro here.

> +		test__fail();
> +		perror("bpf_prog_test_run");
> +		goto out;
> +	} else if (!attr.retval) {
> +		PRINT_FAIL("bpf_prog_test_run: program returned %u\n",
> +			   attr.retval);
> +		goto out;
> +	}
> +
> +	err = bpf_map_lookup_elem(dst, &zero, &dst_cookie);
> +	if (CHECK_FAIL(err)) {
> +		perror("bpf_map_lookup_elem(dst)");
> +		goto out;
> +	}
> +
> +	if (dst_cookie != src_cookie)
> +		PRINT_FAIL("cookie %llu != %llu\n", dst_cookie, src_cookie);

Just replace the whole if statement with a CHECK macro.

> +
> +out:
> +	close(s);
> +	test_sockmap_copy__destroy(skel);
> +}
> +
>   void test_sockmap_basic(void)
>   {
>   	if (test__start_subtest("sockmap create_update_free"))
> @@ -111,4 +183,8 @@ void test_sockmap_basic(void)
>   		test_skmsg_helpers(BPF_MAP_TYPE_SOCKMAP);
>   	if (test__start_subtest("sockhash sk_msg load helpers"))
>   		test_skmsg_helpers(BPF_MAP_TYPE_SOCKHASH);
> +	if (test__start_subtest("sockmap copy"))
> +		test_sockmap_copy(BPF_MAP_TYPE_SOCKMAP);
> +	if (test__start_subtest("sockhash copy"))
> +		test_sockmap_copy(BPF_MAP_TYPE_SOCKHASH);
>   }
> diff --git a/tools/testing/selftests/bpf/progs/test_sockmap_copy.c b/tools/testing/selftests/bpf/progs/test_sockmap_copy.c
> new file mode 100644
> index 000000000000..9d0c9f28cab2
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_sockmap_copy.c
> @@ -0,0 +1,48 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2020 Cloudflare
> +#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);
> +} src SEC(".maps");
> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_SOCKMAP);
> +	__uint(max_entries, 1);
> +	__type(key, __u32);
> +	__type(value, __u64);
> +} dst_sock_map SEC(".maps");
> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_SOCKHASH);
> +	__uint(max_entries, 1);
> +	__type(key, __u32);
> +	__type(value, __u64);
> +} dst_sock_hash SEC(".maps");
> +
> +SEC("classifier/copy_sock_map")
> +int copy_sock_map(void *ctx)
> +{
> +	struct bpf_sock *sk;
> +	bool failed = false;
> +	__u32 key = 0;
> +
> +	sk = bpf_map_lookup_elem(&src, &key);
> +	if (!sk)
> +		return SK_DROP;
> +
> +	if (bpf_map_update_elem(&dst_sock_map, &key, sk, 0))
> +		failed = true;
> +
> +	if (bpf_map_update_elem(&dst_sock_hash, &key, sk, 0))
> +		failed = true;
> +
> +	bpf_sk_release(sk);
> +	return failed ? SK_DROP : SK_PASS;
> +}
> +
> +char _license[] SEC("license") = "GPL";
>