Re: [PATCH bpf-next v2 4/4] libbpf: add selftests for TC-BPF API

This adds some basic tests for the low level bpf_tc_cls_* API.

Reviewed-by: Toke Høiland-Jørgensen <redacted>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
 .../selftests/bpf/prog_tests/test_tc_bpf.c    | 112 ++++++++++++++++++
 .../selftests/bpf/progs/test_tc_bpf_kern.c    |  12 ++
 2 files changed, 124 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/test_tc_bpf.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_tc_bpf_kern.c

diff --git a/tools/testing/selftests/bpf/prog_tests/test_tc_bpf.c b/tools/testing/selftests/bpf/prog_tests/test_tc_bpf.c
new file mode 100644
index 000000000000..945f3a1a72f8
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/test_tc_bpf.c

@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <linux/err.h>
+#include <linux/limits.h>
+#include <bpf/libbpf.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <test_progs.h>
+#include <linux/if_ether.h>
+
+#define LO_IFINDEX 1
+
+static int test_tc_cls_internal(int fd, __u32 parent_id)
+{
+       DECLARE_LIBBPF_OPTS(bpf_tc_cls_opts, opts, .handle = 1, .priority = 10,
+                           .class_id = TC_H_MAKE(1UL << 16, 1),
+                           .chain_index = 5);
+       struct bpf_tc_cls_attach_id id = {};
+       struct bpf_tc_cls_info info = {};
+       int ret;
+
+       ret = bpf_tc_cls_attach(fd, LO_IFINDEX, parent_id, &opts, &id);
+       if (CHECK_FAIL(ret < 0))
+               return ret;
+
+       ret = bpf_tc_cls_get_info(fd, LO_IFINDEX, parent_id, NULL, &info);
+       if (CHECK_FAIL(ret < 0))
+               goto end;
+
+       ret = -1;
+
+       if (CHECK_FAIL(info.id.handle != id.handle) ||
+           CHECK_FAIL(info.id.chain_index != id.chain_index) ||
+           CHECK_FAIL(info.id.priority != id.priority) ||
+           CHECK_FAIL(info.id.handle != 1) ||
+           CHECK_FAIL(info.id.priority != 10) ||
+           CHECK_FAIL(info.class_id != TC_H_MAKE(1UL << 16, 1)) ||
+           CHECK_FAIL(info.id.chain_index != 5))
+               goto end;
+
+       ret = bpf_tc_cls_replace(fd, LO_IFINDEX, parent_id, &opts, &id);
+       if (CHECK_FAIL(ret < 0))
+               return ret;
+
+       if (CHECK_FAIL(info.id.handle != 1) ||
+           CHECK_FAIL(info.id.priority != 10) ||
+           CHECK_FAIL(info.class_id != TC_H_MAKE(1UL << 16, 1)))
+               goto end;
+
+       /* Demonstrate changing attributes */
+       opts.class_id = TC_H_MAKE(1UL << 16, 2);
+
+       ret = bpf_tc_cls_change(fd, LO_IFINDEX, parent_id, &opts, &info.id);
+       if (CHECK_FAIL(ret < 0))
+               goto end;
+
+       ret = bpf_tc_cls_get_info(fd, LO_IFINDEX, parent_id, NULL, &info);
+       if (CHECK_FAIL(ret < 0))
+               goto end;
+
+       if (CHECK_FAIL(info.class_id != TC_H_MAKE(1UL << 16, 2)))
+               goto end;
+       if (CHECK_FAIL((info.bpf_flags & TCA_BPF_FLAG_ACT_DIRECT) != 1))
+               goto end;
+
+end:
+       ret = bpf_tc_cls_detach(LO_IFINDEX, parent_id, &id);
+       CHECK_FAIL(ret < 0);
+       return ret;
+}
+
+void test_test_tc_bpf(void)
+{
+       const char *file = "./test_tc_bpf_kern.o";
+       struct bpf_program *clsp;
+       struct bpf_object *obj;
+       int cls_fd, ret;
+
+       obj = bpf_object__open(file);
+       if (CHECK_FAIL(IS_ERR_OR_NULL(obj)))
+               return;
+
+       clsp = bpf_object__find_program_by_title(obj, "classifier");
+       if (CHECK_FAIL(IS_ERR_OR_NULL(clsp)))
+               goto end;
+
+       ret = bpf_object__load(obj);
+       if (CHECK_FAIL(ret < 0))
+               goto end;
+
+       cls_fd = bpf_program__fd(clsp);
+
+       system("tc qdisc del dev lo clsact");
+
+       ret = test_tc_cls_internal(cls_fd, BPF_TC_CLSACT_INGRESS);
+       if (CHECK_FAIL(ret < 0))
+               goto end;
+
+       if (CHECK_FAIL(system("tc qdisc del dev lo clsact")))
+               goto end;
+
+       ret = test_tc_cls_internal(cls_fd, BPF_TC_CLSACT_EGRESS);
+       if (CHECK_FAIL(ret < 0))
+               goto end;
+
+       CHECK_FAIL(system("tc qdisc del dev lo clsact"));

+
+end:
+       bpf_object__close(obj);
+}

diff --git a/tools/testing/selftests/bpf/progs/test_tc_bpf_kern.c b/tools/testing/selftests/bpf/progs/test_tc_bpf_kern.c
new file mode 100644
index 000000000000..3dd40e21af8e
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_tc_bpf_kern.c

@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+// Dummy prog to test TC-BPF API