[PATCH bpf-next 3/3] selftests/bpf: Add test for xdp_md context in BPF_PROG_TEST_RUN

[Zvi Effron <zeffron@riotgames.com>]

Add a test for using xdp_md as a context to BPF_PROG_TEST_RUN for XDP
programs.

The test uses a BPF program that takes in a return value from XDP
metadata, then reduces the size of the XDP metadata by 4 bytes.

Test cases validate the possible failure cases for passing in invalid
xdp_md contexts, that the return value is successfully passed
in, and that the adjusted metadata is successfully copied out.

Co-developed-by: Cody Haas <chaas@riotgames.com>
Signed-off-by: Cody Haas <chaas@riotgames.com>
Co-developed-by: Lisa Watanabe <lwatanabe@riotgames.com>
Signed-off-by: Lisa Watanabe <lwatanabe@riotgames.com>
Signed-off-by: Zvi Effron <zeffron@riotgames.com>
---
 .../bpf/prog_tests/xdp_context_test_run.c     | 117 ++++++++++++++++++
 .../bpf/progs/test_xdp_context_test_run.c     |  22 ++++
 2 files changed, 139 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_context_test_run.c

diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c b/tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c
new file mode 100644
index 000000000000..92ce2e4a5c30
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include <network_helpers.h>
+
+void test_xdp_context_test_run(void)
+{
+	const char *file = "./test_xdp_context_test_run.o";
+	struct bpf_object *obj;
+	char data[sizeof(pkt_v4) + sizeof(__u32)];
+	char buf[128];
+	char bad_ctx[sizeof(struct xdp_md)];
+	struct xdp_md ctx_in, ctx_out;
+	struct bpf_test_run_opts tattr = {
+		.sz = sizeof(struct bpf_test_run_opts),
+		.data_in = &data,
+		.data_out = buf,
+		.data_size_in = sizeof(data),
+		.data_size_out = sizeof(buf),
+		.ctx_out = &ctx_out,
+		.ctx_size_out = sizeof(ctx_out),
+		.repeat = 1,
+	};
+	int err, prog_fd;
+
+	err = bpf_prog_load(file, BPF_PROG_TYPE_XDP, &obj, &prog_fd);
+	if (CHECK_FAIL(err))
+		return;
+
+	*(__u32 *)data = XDP_PASS;
+	*(struct ipv4_packet *)(data + sizeof(__u32)) = pkt_v4;
+
+	memset(&ctx_in, 0, sizeof(ctx_in));
+	tattr.ctx_in = &ctx_in;
+	tattr.ctx_size_in = sizeof(ctx_in);
+
+	tattr.ctx_in = &ctx_in;
+	tattr.ctx_size_in = sizeof(ctx_in);
+	ctx_in.data_meta = 0;
+	ctx_in.data = sizeof(__u32);
+	ctx_in.data_end = ctx_in.data + sizeof(pkt_v4);
+	err = bpf_prog_test_run_opts(prog_fd, &tattr);
+	CHECK_ATTR(err || tattr.retval != XDP_PASS ||
+		   tattr.data_size_out != sizeof(pkt_v4) ||
+		   tattr.ctx_size_out != tattr.ctx_size_in ||
+		   ctx_out.data_meta != 0 ||
+		   ctx_out.data != ctx_out.data_meta ||
+		   ctx_out.data_end != sizeof(pkt_v4), "xdp_md context",
+		   "err %d errno %d retval %d data size out %d context size out %d data_meta %d data %d data_end %d\n",
+		   err, errno, tattr.retval, tattr.data_size_out,
+		   tattr.ctx_size_out, ctx_out.data_meta, ctx_out.data,
+		   ctx_out.data_end);
+
+	/* Data past the end of the kernel's struct xdp_md must be 0 */
+	bad_ctx[sizeof(bad_ctx) - 1] = 1;
+	tattr.ctx_in = bad_ctx;
+	tattr.ctx_size_in = sizeof(bad_ctx);
+	err = bpf_prog_test_run_opts(prog_fd, &tattr);
+	CHECK_ATTR(!err || errno != 22, "bad context", "err %d errno %d\n",
+		   err, errno);
+
+	/* The egress cannot be specified */
+	ctx_in.egress_ifindex = 1;
+	err = bpf_prog_test_run_opts(prog_fd, &tattr);
+	CHECK_ATTR(!err || errno != 22,
+		   "nonzero egress index", "err %d errno %d\n", err, errno);
+
+	/* data_meta must reference the start of data */
+	ctx_in.data_meta = sizeof(__u32);
+	ctx_in.data = ctx_in.data_meta;
+	ctx_in.data_end = ctx_in.data + sizeof(pkt_v4);
+	ctx_in.egress_ifindex = 0;
+	err = bpf_prog_test_run_opts(prog_fd, &tattr);
+	CHECK_ATTR(!err || errno != 22, "nonzero data_meta",
+		   "err %d errno %d\n", err, errno);
+
+	/* Metadata must be 32 bytes or smaller */
+	ctx_in.data_meta = 0;
+	ctx_in.data = sizeof(__u32)*9;
+	ctx_in.data_end = ctx_in.data + sizeof(pkt_v4);
+	err = bpf_prog_test_run_opts(prog_fd, &tattr);
+	CHECK_ATTR(!err || errno != 22, "metadata too long",
+		   "err %d errno %d\n", err, errno);
+
+	/* Metadata's size must be a multiple of 4 */
+	ctx_in.data = 3;
+	err = bpf_prog_test_run_opts(prog_fd, &tattr);
+	CHECK_ATTR(!err || errno != 22, "multiple of 4",
+		   "err %d errno %d\n", err, errno);
+
+	/* Total size of data must match data_end - data_meta */
+	ctx_in.data = 0;
+	ctx_in.data_end = sizeof(pkt_v4) - 4;
+	err = bpf_prog_test_run_opts(prog_fd, &tattr);
+	CHECK_ATTR(!err || errno != 22, "data too long", "err %d errno %d\n",
+		   err, errno);
+
+	ctx_in.data_end = sizeof(pkt_v4) + 4;
+	err = bpf_prog_test_run_opts(prog_fd, &tattr);
+	CHECK_ATTR(!err || errno != 22, "data too short", "err %d errno %d\n",
+		   err, errno);
+
+	/* RX queue cannot be specified without specifying an ingress */
+	ctx_in.data_end = sizeof(pkt_v4);
+	ctx_in.ingress_ifindex = 0;
+	ctx_in.rx_queue_index = 1;
+	err = bpf_prog_test_run_opts(prog_fd, &tattr);
+	CHECK_ATTR(!err || errno != 22, "no ingress if",
+		   "err %d, rx_queue_index %d\n", err, ctx_out.rx_queue_index);
+
+	ctx_in.ingress_ifindex = 1;
+	ctx_in.rx_queue_index = 1;
+	err = bpf_prog_test_run_opts(prog_fd, &tattr);
+	CHECK_ATTR(!err || errno != 22, "invalid rx queue",
+		   "err %d, rx_queue_index %d\n", err, ctx_out.rx_queue_index);
+
+	bpf_object__close(obj);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_xdp_context_test_run.c b/tools/testing/selftests/bpf/progs/test_xdp_context_test_run.c
new file mode 100644
index 000000000000..c66a756b238e
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_xdp_context_test_run.c
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+int _version SEC("version") = 1;
+
+SEC("xdp_context")
+int _xdp_context(struct xdp_md *xdp)
+{
+	void *data = (void *)(unsigned long)xdp->data;
+	__u32 *metadata = (void *)(unsigned long)xdp->data_meta;
+	__u32 ret;
+
+	if (metadata + 1 > data)
+		return XDP_ABORTED;
+	ret = *metadata;
+	if (bpf_xdp_adjust_meta(xdp, 4))
+		return XDP_ABORTED;
+	return ret;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.31.1