Re: [bpf-next PATCH v3 4/5] bpf: selftests, add sk_msg helpers load and attach test

The test itself is not particularly useful but it encodes a common
pattern we have.

Namely do a sk storage lookup then depending on data here decide if
we need to do more work or alternatively allow packet to PASS. Then
if we need to do more work consult task_struct for more information
about the running task. Finally based on this additional information
drop or pass the data. In this case the suspicious check is not so
realisitic but it encodes the general pattern and uses the helpers
so we test the workflow.

This is a load test to ensure verifier correctly handles this case.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
---
 .../selftests/bpf/prog_tests/sockmap_basic.c       |   57 ++++++++++++++++++++
 .../selftests/bpf/progs/test_skmsg_load_helpers.c  |   48 +++++++++++++++++
 2 files changed, 105 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/test_skmsg_load_helpers.c

diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
index aa43e0b..cacb4ad 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c

@@ -1,13 +1,46 @@
 // SPDX-License-Identifier: GPL-2.0
 // Copyright (c) 2020 Cloudflare
+#include <error.h>

 #include "test_progs.h"
+#include "test_skmsg_load_helpers.skel.h"

 #define TCP_REPAIR             19      /* TCP sock is under repair right now */

 #define TCP_REPAIR_ON          1
 #define TCP_REPAIR_OFF_NO_WP   -1      /* Turn off without window probes */

+#define _FAIL(errnum, fmt...)                                                  \
+       ({                                                                     \
+               error_at_line(0, (errnum), __func__, __LINE__, fmt);           \
+               CHECK_FAIL(true);                                              \
+       })
+#define FAIL(fmt...) _FAIL(0, fmt)
+#define FAIL_ERRNO(fmt...) _FAIL(errno, fmt)
+#define FAIL_LIBBPF(err, msg)                                                  \
+       ({                                                                     \
+               char __buf[MAX_STRERR_LEN];                                    \
+               libbpf_strerror((err), __buf, sizeof(__buf));                  \
+               FAIL("%s: %s", (msg), __buf);                                  \
+       })
+
+#define xbpf_prog_attach(prog, target, type, flags)                            \
+       ({                                                                     \
+               int __ret =                                                    \
+                       bpf_prog_attach((prog), (target), (type), (flags));    \
+               if (__ret == -1)                                               \
+                       FAIL_ERRNO("prog_attach(" #type ")");                  \
+               __ret;                                                         \
+       })
+
+#define xbpf_prog_detach2(prog, target, type)                                  \
+       ({                                                                     \
+               int __ret = bpf_prog_detach2((prog), (target), (type));        \
+               if (__ret == -1)                                               \
+                       FAIL_ERRNO("prog_detach2(" #type ")");                 \
+               __ret;                                                         \
+       })

+
 static int connected_socket_v4(void)
 {
        struct sockaddr_in addr = {

@@ -70,10 +103,34 @@ static void test_sockmap_create_update_free(enum bpf_map_type map_type)
        close(s);
 }

+static void test_skmsg_helpers(enum bpf_map_type map_type)
+{
+       struct test_skmsg_load_helpers *skel;
+       int err, map, verdict;
+
+       skel = test_skmsg_load_helpers__open_and_load();
+       if (!skel) {
+               FAIL("skeleton open/load failed");
+               return;
+       }
+
+       verdict = bpf_program__fd(skel->progs.prog_msg_verdict);
+       map = bpf_map__fd(skel->maps.sock_map);
+
+       err = xbpf_prog_attach(verdict, map, BPF_SK_MSG_VERDICT, 0);
+       if (err)
+               return;
+       xbpf_prog_detach2(verdict, map, BPF_SK_MSG_VERDICT);