On Tue, Dec 13, 2022 at 5:05 PM Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote:
>
> This adds a simple test for inserting an XDP program into a cpumap that is
> "owned" by an XDP program that was loaded as PROG_TYPE_EXT (as libxdp
> does). Prior to the kernel fix this would fail because the map type
> ownership would be set to PROG_TYPE_EXT instead of being resolved to
> PROG_TYPE_XDP.
>
> v4:
> - Use skeletons for selftest
> v3:
> - Update comment to better explain the cause
> - Add Yonghong's ACK
>
> Acked-by: Yonghong Song <yhs@xxxxxx>
> Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
> ---
> .../selftests/bpf/prog_tests/fexit_bpf2bpf.c | 54 +++++++++++++++++++
> .../selftests/bpf/progs/freplace_progmap.c | 24 +++++++++
> 2 files changed, 78 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/progs/freplace_progmap.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
> index d1e32e792536..efa1fc65840d 100644
> --- a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
> +++ b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
> @@ -4,6 +4,8 @@
> #include <network_helpers.h>
> #include <bpf/btf.h>
> #include "bind4_prog.skel.h"
> +#include "freplace_progmap.skel.h"
> +#include "xdp_dummy.skel.h"
>
> typedef int (*test_cb)(struct bpf_object *obj);
>
> @@ -500,6 +502,56 @@ static void test_fentry_to_cgroup_bpf(void)
> bind4_prog__destroy(skel);
> }
>
> +static void test_func_replace_progmap(void)
> +{
> + struct bpf_cpumap_val value = { .qsize = 1 };
> + struct freplace_progmap *skel = NULL;
> + struct xdp_dummy *tgt_skel = NULL;
> + int err, tgt_fd;
> + __u32 key = 0;
> +
> + skel = freplace_progmap__open();
> + if (!ASSERT_OK_PTR(skel, "prog_open"))
> + return;
> +
> + tgt_skel = xdp_dummy__open_and_load();
> + if (!ASSERT_OK_PTR(tgt_skel, "tgt_prog_load"))
> + goto out;
> +
> + tgt_fd = bpf_program__fd(tgt_skel->progs.xdp_dummy_prog);
> +
> + /* Change the 'redirect' program type to be a PROG_TYPE_EXT
> + * with an XDP target
> + */
> + bpf_program__set_type(skel->progs.xdp_cpumap_prog, BPF_PROG_TYPE_EXT);
> + bpf_program__set_expected_attach_type(skel->progs.xdp_cpumap_prog, 0);
you shouldn't need this manual override if you mark xdp_cpumap_prog as
SEC("freplace"), or am I missing something?
but other than this minor thing looks good to me, thanks
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> + err = bpf_program__set_attach_target(skel->progs.xdp_cpumap_prog,
> + tgt_fd, "xdp_dummy_prog");
> + if (!ASSERT_OK(err, "set_attach_target"))
> + goto out;
> +
> + err = freplace_progmap__load(skel);
> + if (!ASSERT_OK(err, "obj_load"))
> + goto out;
> +
> + /* Prior to fixing the kernel, loading the PROG_TYPE_EXT 'redirect'
> + * program above will cause the map owner type of 'cpumap' to be set to
> + * PROG_TYPE_EXT. This in turn will cause the bpf_map_update_elem()
> + * below to fail, because the program we are inserting into the map is
> + * of PROG_TYPE_XDP. After fixing the kernel, the initial ownership will
> + * be correctly resolved to the *target* of the PROG_TYPE_EXT program
> + * (i.e., PROG_TYPE_XDP) and the map update will succeed.
> + */
> + value.bpf_prog.fd = bpf_program__fd(skel->progs.xdp_drop_prog);
> + err = bpf_map_update_elem(bpf_map__fd(skel->maps.cpu_map),
> + &key, &value, 0);
> + ASSERT_OK(err, "map_update");
> +
> +out:
> + xdp_dummy__destroy(tgt_skel);
> + freplace_progmap__destroy(skel);
> +}
> +
> /* NOTE: affect other tests, must run in serial mode */
> void serial_test_fexit_bpf2bpf(void)
> {
> @@ -525,4 +577,6 @@ void serial_test_fexit_bpf2bpf(void)
> test_func_replace_global_func();
> if (test__start_subtest("fentry_to_cgroup_bpf"))
> test_fentry_to_cgroup_bpf();
> + if (test__start_subtest("func_replace_progmap"))
> + test_func_replace_progmap();
> }
> diff --git a/tools/testing/selftests/bpf/progs/freplace_progmap.c b/tools/testing/selftests/bpf/progs/freplace_progmap.c
> new file mode 100644
> index 000000000000..68174c3d7b37
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/freplace_progmap.c
> @@ -0,0 +1,24 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_CPUMAP);
> + __uint(key_size, sizeof(__u32));
> + __uint(value_size, sizeof(struct bpf_cpumap_val));
ok, another minor nit which you ignored, libbpf should be smart enough to accept
__type(key, __u32);
__type(value, struct bpf_cpumap_val);
And if it's not it would be good to know that it's not (and trivially fix it).
> + __uint(max_entries, 1);
> +} cpu_map SEC(".maps");
> +
> +SEC("xdp/cpumap")
> +int xdp_drop_prog(struct xdp_md *ctx)
> +{
> + return XDP_DROP;
> +}
> +
> +SEC("xdp")
> +int xdp_cpumap_prog(struct xdp_md *ctx)
> +{
> + return bpf_redirect_map(&cpu_map, 0, XDP_PASS);
> +}
> +
> +char _license[] SEC("license") = "GPL";
> --
> 2.38.1
>
