On Fri, Nov 20, 2020 at 05:18:47PM +0100, Jesper Dangaard Brouer wrote:
> Adding selftest for BPF-helper bpf_check_mtu(). Making sure
> it can be used from both XDP and TC.
>
> Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
> ---
> tools/testing/selftests/bpf/prog_tests/check_mtu.c | 37 ++++++++++++++++++++
> tools/testing/selftests/bpf/progs/test_check_mtu.c | 33 ++++++++++++++++++
> 2 files changed, 70 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/prog_tests/check_mtu.c
> create mode 100644 tools/testing/selftests/bpf/progs/test_check_mtu.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/check_mtu.c b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
> new file mode 100644
> index 000000000000..09b8f986a17b
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
> @@ -0,0 +1,37 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2020 Red Hat */
> +#include <uapi/linux/bpf.h>
> +#include <linux/if_link.h>
> +#include <test_progs.h>
> +
> +#include "test_check_mtu.skel.h"
> +#define IFINDEX_LO 1
> +
> +void test_check_mtu_xdp(struct test_check_mtu *skel)
> +{
> + int err = 0;
> + int fd;
> +
> + fd = bpf_program__fd(skel->progs.xdp_use_helper);
> + err = bpf_set_link_xdp_fd(IFINDEX_LO, fd, XDP_FLAGS_SKB_MODE);
> + if (CHECK_FAIL(err))
> + return;
> +
> + bpf_set_link_xdp_fd(IFINDEX_LO, -1, 0);
> +}
> +
> +void test_check_mtu(void)
> +{
> + struct test_check_mtu *skel;
> +
> + skel = test_check_mtu__open_and_load();
> + if (CHECK_FAIL(!skel)) {
> + perror("test_check_mtu__open_and_load");
> + return;
> + }
> +
> + if (test__start_subtest("bpf_check_mtu XDP-attach"))
> + test_check_mtu_xdp(skel);
> +
> + test_check_mtu__destroy(skel);
> +}
> diff --git a/tools/testing/selftests/bpf/progs/test_check_mtu.c b/tools/testing/selftests/bpf/progs/test_check_mtu.c
> new file mode 100644
> index 000000000000..ab97ec925a32
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_check_mtu.c
> @@ -0,0 +1,33 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2020 Red Hat */
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +
> +#include <stddef.h>
> +#include <stdint.h>
> +
> +char _license[] SEC("license") = "GPL";
> +
> +SEC("xdp")
> +int xdp_use_helper(struct xdp_md *ctx)
> +{
> + uint32_t mtu_len = 0;
> + int delta = 20;
> +
> + if (bpf_check_mtu(ctx, 0, &mtu_len, delta, 0)) {
> + return XDP_ABORTED;
> + }
> + return XDP_PASS;
> +}
> +
> +SEC("classifier")
> +int tc_use_helper(struct __sk_buff *ctx)
> +{
> + uint32_t mtu_len = 0;
> + int delta = -20;
> +
> + if (bpf_check_mtu(ctx, 0, &mtu_len, delta, 0)) {
> + return BPF_DROP;
> + }
> + return BPF_OK;
> +}
Patches 7 and 8 are not adequate as tests.
They do not testing the functionality of earlier patches.
bpf_check_mtu() could be returning random value and "tests" 7 and 8 would still pass.
Please fix.
