[PATCH bpf-next v3 7/8] selftests/bpf: Add selftest for XDP_REDIRECT in bpf_prog_run()

["Toke Høiland-Jørgensen" <toke@redhat.com>]

This adds a selftest for the XDP_REDIRECT facility in bpf_prog_run, that
redirects packets into a veth and counts them using an XDP program on the
other side of the veth pair.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 .../bpf/prog_tests/xdp_do_redirect.c          | 74 +++++++++++++++++++
 .../bpf/progs/test_xdp_do_redirect.c          | 34 +++++++++
 2 files changed, 108 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_do_redirect.c

diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c b/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c
new file mode 100644
index 000000000000..c2effcf076a6
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include <network_helpers.h>
+#include <net/if.h>
+#include "test_xdp_do_redirect.skel.h"
+
+#define SYS(fmt, ...)						\
+	({							\
+		char cmd[1024];					\
+		snprintf(cmd, sizeof(cmd), fmt, ##__VA_ARGS__);	\
+		if (!ASSERT_OK(system(cmd), cmd))		\
+			goto fail;				\
+	})
+
+#define NUM_PKTS 10
+void test_xdp_do_redirect(void)
+{
+	struct test_xdp_do_redirect *skel = NULL;
+	struct ipv6_packet data = pkt_v6;
+	struct xdp_md ctx_in = { .data_end = sizeof(data) };
+	__u8 dst_mac[ETH_ALEN] = {0x00, 0x11, 0x22, 0x33, 0x44, 0x55};
+	__u8 src_mac[ETH_ALEN] = {0x66, 0x77, 0x88, 0x99, 0xaa, 0xbb};
+	DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
+			    .data_in = &data,
+			    .data_size_in = sizeof(data),
+			    .ctx_in = &ctx_in,
+			    .ctx_size_in = sizeof(ctx_in),
+			    .flags = BPF_F_TEST_XDP_DO_REDIRECT,
+			    .repeat = NUM_PKTS,
+		);
+	int err, prog_fd, ifindex_src, ifindex_dst;
+	struct bpf_link *link;
+
+	memcpy(data.eth.h_dest, dst_mac, ETH_ALEN);
+	memcpy(data.eth.h_source, src_mac, ETH_ALEN);
+
+	skel = test_xdp_do_redirect__open();
+	if (!ASSERT_OK_PTR(skel, "skel"))
+		return;
+
+	SYS("ip link add veth_src type veth peer name veth_dst");
+	SYS("ip link set dev veth_src up");
+	SYS("ip link set dev veth_dst up");
+
+	ifindex_src = if_nametoindex("veth_src");
+	ifindex_dst = if_nametoindex("veth_dst");
+	if (!ASSERT_NEQ(ifindex_src, 0, "ifindex_src") ||
+	    !ASSERT_NEQ(ifindex_dst, 0, "ifindex_dst"))
+		goto fail;
+
+	memcpy(skel->rodata->expect_dst, dst_mac, ETH_ALEN);
+	skel->rodata->ifindex_out = ifindex_src;
+
+	if (!ASSERT_OK(test_xdp_do_redirect__load(skel), "load"))
+		goto fail;
+
+	link = bpf_program__attach_xdp(skel->progs.xdp_count_pkts, ifindex_dst);
+	if (!ASSERT_OK_PTR(link, "prog_attach"))
+		goto fail;
+	skel->links.xdp_count_pkts = link;
+
+	prog_fd = bpf_program__fd(skel->progs.xdp_redirect_notouch);
+	err = bpf_prog_test_run_opts(prog_fd, &opts);
+	if (!ASSERT_OK(err, "prog_run"))
+		goto fail;
+
+	/* wait for the packets to be flushed */
+	kern_sync_rcu();
+
+	ASSERT_EQ(skel->bss->pkts_seen, NUM_PKTS, "pkt_count");
+fail:
+	system("ip link del dev veth_src");
+	test_xdp_do_redirect__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_xdp_do_redirect.c b/tools/testing/selftests/bpf/progs/test_xdp_do_redirect.c
new file mode 100644
index 000000000000..254ebf523f37
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_xdp_do_redirect.c
@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+
+#define ETH_ALEN 6
+const volatile int ifindex_out;
+const volatile __u8 expect_dst[ETH_ALEN];
+volatile int pkts_seen = 0;
+
+SEC("xdp")
+int xdp_redirect_notouch(struct xdp_md *xdp)
+{
+	return bpf_redirect(ifindex_out, 0);
+}
+
+SEC("xdp")
+int xdp_count_pkts(struct xdp_md *xdp)
+{
+	void *data = (void *)(long)xdp->data;
+	void *data_end = (void *)(long)xdp->data_end;
+	struct ethhdr *eth = data;
+	int i;
+
+	if (eth + 1 > data_end)
+		return XDP_ABORTED;
+
+	for (i = 0; i < ETH_ALEN; i++)
+		if (expect_dst[i] != eth->h_dest[i])
+			return XDP_ABORTED;
+	pkts_seen++;
+	return XDP_DROP;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.34.0