Re: [PATCH v3 bpf-next 5/5] selftest: Add tests for XDP programs in devmap entries

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

David Ahern <dsahern@kernel.org> writes:

> Add tests to verify ability to add an XDP program to a
> entry in a DEVMAP.
>
> Add negative tests to show DEVMAP programs can not be
> attached to devices as a normal XDP program, and accesses
> to egress_ifindex require BPF_XDP_DEVMAP attach type.
>
> Signed-off-by: David Ahern <dsahern@kernel.org>
> ---
>  .../bpf/prog_tests/xdp_devmap_attach.c        | 89 +++++++++++++++++++
>  .../bpf/progs/test_xdp_devmap_helpers.c       | 22 +++++
>  .../bpf/progs/test_xdp_with_devmap_helpers.c  | 43 +++++++++
>  3 files changed, 154 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_with_devmap_helpers.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c b/tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c
> new file mode 100644
> index 000000000000..caeea19f2772
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c
> @@ -0,0 +1,89 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <uapi/linux/bpf.h>
> +#include <linux/if_link.h>
> +#include <test_progs.h>
> +
> +#include "test_xdp_devmap_helpers.skel.h"
> +#include "test_xdp_with_devmap_helpers.skel.h"
> +
> +#define IFINDEX_LO 1
> +
> +void test_xdp_with_devmap_helpers(void)
> +{
> +	struct test_xdp_with_devmap_helpers *skel;
> +	struct bpf_prog_info info = {};
> +	struct bpf_devmap_val val = {
> +		.ifindex = IFINDEX_LO,
> +	};
> +	__u32 id, len = sizeof(info);
> +	__u32 duration, idx = 0;
> +	int err, dm_fd, map_fd;
> +
> +
> +	skel = test_xdp_with_devmap_helpers__open_and_load();
> +	if (CHECK_FAIL(!skel)) {
> +		perror("test_xdp_with_devmap_helpers__open_and_load");
> +		return;
> +	}
> +
> +	/* can not attach program with DEVMAPs that allow programs
> +	 * as xdp generic
> +	 */
> +	dm_fd = bpf_program__fd(skel->progs.xdp_redir_prog);
> +	err = bpf_set_link_xdp_fd(IFINDEX_LO, dm_fd, XDP_FLAGS_SKB_MODE);
> +	CHECK(err == 0, "Generic attach of program with 8-byte devmap",
> +	      "should have failed\n");
> +
> +	dm_fd = bpf_program__fd(skel->progs.xdp_dummy_dm);
> +	map_fd = bpf_map__fd(skel->maps.dm_ports);
> +	err = bpf_obj_get_info_by_fd(dm_fd, &info, &len);
> +	if (CHECK_FAIL(err))
> +		goto out_close;
> +
> +	val.bpf_prog_fd = dm_fd;
> +	err = bpf_map_update_elem(map_fd, &idx, &val, 0);
> +	CHECK(err, "Add program to devmap entry",
> +	      "err %d errno %d\n", err, errno);
> +
> +	err = bpf_map_lookup_elem(map_fd, &id, &val);
> +	CHECK(err, "Read devmap entry", "err %d errno %d\n", err, errno);
> +	CHECK(info.id != val.bpf_prog_id, "Expected program id in devmap entry",
> +	      "expected %u read %u\n", info.id, val.bpf_prog_id);
> +
> +	/* can not attach BPF_XDP_DEVMAP program to a device */
> +	err = bpf_set_link_xdp_fd(IFINDEX_LO, dm_fd, XDP_FLAGS_SKB_MODE);
> +	CHECK(err == 0, "Attach of BPF_XDP_DEVMAP program",
> +	      "should have failed\n");
> +
> +	val.ifindex = 1;
> +	val.bpf_prog_fd = bpf_program__fd(skel->progs.xdp_dummy_prog);
> +	err = bpf_map_update_elem(map_fd, &idx, &val, 0);
> +	CHECK(err == 0, "Add non-BPF_XDP_DEVMAP program to devmap entry",
> +	      "should have failed\n");
> +
> +out_close:
> +	test_xdp_with_devmap_helpers__destroy(skel);
> +}
> +
> +void test_neg_xdp_devmap_helpers(void)
> +{
> +	struct test_xdp_devmap_helpers *skel;
> +	__u32 duration;
> +
> +	skel = test_xdp_devmap_helpers__open_and_load();
> +	if (CHECK(skel,
> +		  "Load of XDP program accessing egress ifindex without attach type",
> +		  "should have failed\n")) {
> +		test_xdp_devmap_helpers__destroy(skel);
> +	}
> +}
> +
> +
> +void test_xdp_devmap_attach(void)
> +{
> +	if (test__start_subtest("DEVMAP with programs in entries"))
> +		test_xdp_with_devmap_helpers();
> +
> +	if (test__start_subtest("Verifier check of DEVMAP programs"))
> +		test_neg_xdp_devmap_helpers();
> +}
> diff --git a/tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c b/tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c
> new file mode 100644
> index 000000000000..b360ba2bd441
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c
> @@ -0,0 +1,22 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* fails to load without expected_attach_type = BPF_XDP_DEVMAP
> + * because of access to egress_ifindex
> + */
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +
> +SEC("xdp_dm_log")

Guess this should be xdp_devmap_log now?

-Toke