selftests/bpf: Adding test for arg dereference in extension trace

Adding test that setup following program: SEC("classifier/test_pkt_md_access") int test_pkt_md_access(struct __sk_buff *skb) with its extension: SEC("freplace/test_pkt_md_access") int test_pkt_md_access_new(struct __sk_buff *skb) and tracing that extension with: SEC("fentry/test_pkt_md_access_new") int BPF_PROG(fentry, struct sk_buff *skb) The test verifies that the tracing program can dereference skb argument properly. Acked-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>

Author: olsajiri

tools/testing/selftests/bpf/prog_tests/trace_ext.c

@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define _GNU_SOURCE
+#include <test_progs.h>
+#include <network_helpers.h>
+#include <sys/stat.h>
+#include <linux/sched.h>
+#include <sys/syscall.h>
+
+#include "test_pkt_md_access.skel.h"
+#include "test_trace_ext.skel.h"
+#include "test_trace_ext_tracing.skel.h"
+
+static __u32 duration;
+
+void test_trace_ext(void)
+{
+struct test_pkt_md_access *skel_pkt = NULL;
+struct test_trace_ext_tracing *skel_trace = NULL;
+struct test_trace_ext_tracing__bss *bss_trace;
+struct test_trace_ext *skel_ext = NULL;
+struct test_trace_ext__bss *bss_ext;
+int err, pkt_fd, ext_fd;
+struct bpf_program *prog;
+char buf[100];
+__u32 retval;
+__u64 len;
+
+/* open/load/attach test_pkt_md_access */
+skel_pkt = test_pkt_md_access__open_and_load();
+if (CHECK(!skel_pkt, "setup", "classifier/test_pkt_md_access open failed\n"))
+goto cleanup;
+
+err = test_pkt_md_access__attach(skel_pkt);
+if (CHECK(err, "setup", "classifier/test_pkt_md_access attach failed: %d\n", err))
+goto cleanup;
+
+prog = skel_pkt->progs.test_pkt_md_access;
+pkt_fd = bpf_program__fd(prog);
+
+/* open extension */
+skel_ext = test_trace_ext__open();
+if (CHECK(!skel_ext, "setup", "freplace/test_pkt_md_access open failed\n"))
+goto cleanup;
+
+/* set extension's attach target - test_pkt_md_access */
+prog = skel_ext->progs.test_pkt_md_access_new;
+bpf_program__set_attach_target(prog, pkt_fd, "test_pkt_md_access");
+
+/* load/attach extension */
+err = test_trace_ext__load(skel_ext);
+if (CHECK(err, "setup", "freplace/test_pkt_md_access load failed\n")) {
+libbpf_strerror(err, buf, sizeof(buf));
+fprintf(stderr, "%s\n", buf);
+goto cleanup;
+}
+
+err = test_trace_ext__attach(skel_ext);
+if (CHECK(err, "setup", "freplace/test_pkt_md_access attach failed: %d\n", err))
+goto cleanup;
+
+prog = skel_ext->progs.test_pkt_md_access_new;
+ext_fd = bpf_program__fd(prog);
+
+/* open tracing */
+skel_trace = test_trace_ext_tracing__open();
+if (CHECK(!skel_trace, "setup", "tracing/test_pkt_md_access_new open failed\n"))
+goto cleanup;
+
+/* set tracing's attach target - fentry */
+prog = skel_trace->progs.fentry;
+bpf_program__set_attach_target(prog, ext_fd, "test_pkt_md_access_new");
+
+/* set tracing's attach target - fexit */
+prog = skel_trace->progs.fexit;
+bpf_program__set_attach_target(prog, ext_fd, "test_pkt_md_access_new");
+
+/* load/attach tracing */
+err = test_trace_ext_tracing__load(skel_trace);
+if (CHECK(err, "setup", "tracing/test_pkt_md_access_new load failed\n")) {
+libbpf_strerror(err, buf, sizeof(buf));
+fprintf(stderr, "%s\n", buf);
+goto cleanup;
+}
+
+err = test_trace_ext_tracing__attach(skel_trace);
+if (CHECK(err, "setup", "tracing/test_pkt_md_access_new attach failed: %d\n", err))
+goto cleanup;
+
+/* trigger the test */
+err = bpf_prog_test_run(pkt_fd, 1, &pkt_v4, sizeof(pkt_v4),
+NULL, NULL, &retval, &duration);
+CHECK(err || retval, "run", "err %d errno %d retval %d\n", err, errno, retval);
+
+bss_ext = skel_ext->bss;
+bss_trace = skel_trace->bss;
+
+len = bss_ext->ext_called;
+
+CHECK(bss_ext->ext_called == 0,
+"check", "failed to trigger freplace/test_pkt_md_access\n");
+CHECK(bss_trace->fentry_called != len,
+"check", "failed to trigger fentry/test_pkt_md_access_new\n");
+CHECK(bss_trace->fexit_called != len,
+"check", "failed to trigger fexit/test_pkt_md_access_new\n");
+
+cleanup:
+test_trace_ext_tracing__destroy(skel_trace);
+test_trace_ext__destroy(skel_ext);
+test_pkt_md_access__destroy(skel_pkt);
+}

tools/testing/selftests/bpf/progs/test_trace_ext.c

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+#include <linux/bpf.h>
+#include <stdbool.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
+#include <bpf/bpf_tracing.h>
+
+__u64 ext_called = 0;
+
+SEC("freplace/test_pkt_md_access")
+int test_pkt_md_access_new(struct __sk_buff *skb)
+{
+ext_called = skb->len;
+return 0;
+}
+
+char _license[] SEC("license") = "GPL";

tools/testing/selftests/bpf/progs/test_trace_ext_tracing.c

@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+__u64 fentry_called = 0;
+
+SEC("fentry/test_pkt_md_access_new")
+int BPF_PROG(fentry, struct sk_buff *skb)
+{
+fentry_called = skb->len;
+return 0;
+}
+
+__u64 fexit_called = 0;
+
+SEC("fexit/test_pkt_md_access_new")
+int BPF_PROG(fexit, struct sk_buff *skb)
+{
+fexit_called = skb->len;
+return 0;
+}
+
+char _license[] SEC("license") = "GPL";