Re: [PATCH bpf-next 6/6] selftests: bpf: test sockmap update from BPF

On Wed, 19 Aug 2020 at 21:46, Yonghong Song yhs@fb.com wrote:

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?

Yup!

...

• 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.

I avoid CHECK because it requires `duration`, which doesn't make sense for most things that I call CHECK_FAIL on here. So either it outputs 0 nsec (which is bogus) or it outputs the value from the last bpf_prog_test_run call (which is also bogus). How do other tests handle this? Just ignore it?

...

• 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?

Hm, good point. This is a quirk of the sockmap API, I need to dig into this a bit.

...

• 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.

See above, re duration.

...

+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";