Commit f506439e authored by Toke Høiland-Jørgensen's avatar Toke Høiland-Jørgensen Committed by Martin KaFai Lau
Browse files

selftests/bpf: Add a test for using a cpumap from an freplace-to-XDP program 



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.

v5:
- Fix a few nits from Andrii, add his ACK
v4:
- Use skeletons for selftest
v3:
- Update comment to better explain the cause
- Add Yonghong's ACK

Acked-by: default avatarYonghong Song <yhs@fb.com>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20221214230254.790066-2-toke@redhat.com


Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
parent 1c123c56

tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c

+48 −0
Original line number Diff line number Diff line
@@ -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 +502,50 @@ 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;

	__u32 key = 0;

	int err;



	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;



	err = bpf_program__set_attach_target(skel->progs.xdp_cpumap_prog,

					     bpf_program__fd(tgt_skel->progs.xdp_dummy_prog),

					     "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 +571,6 @@ 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();

}

tools/testing/selftests/bpf/progs/freplace_progmap.c

0 → 100644
+24 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>



struct {

	__uint(type, BPF_MAP_TYPE_CPUMAP);

	__type(key, __u32);

	__type(value, struct bpf_cpumap_val);

	__uint(max_entries, 1);

} cpu_map SEC(".maps");



SEC("xdp/cpumap")

int xdp_drop_prog(struct xdp_md *ctx)

{

	return XDP_DROP;

}



SEC("freplace")

int xdp_cpumap_prog(struct xdp_md *ctx)

{

	return bpf_redirect_map(&cpu_map, 0, XDP_PASS);

}



char _license[] SEC("license") = "GPL";