Add selftests to exercise FD-based cgroup BPF program attachments and their
intermixing with legacy cgroup BPF attachments. Auto-detachment and program
replacement (both unconditional and cmpxchng-like) are tested as well.
Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
---
.../selftests/bpf/prog_tests/cgroup_link.c | 244 ++++++++++++++++++
.../selftests/bpf/progs/test_cgroup_link.c | 24 ++
2 files changed, 268 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/cgroup_link.c
create mode 100644 tools/testing/selftests/bpf/progs/test_cgroup_link.c
diff --git a/tools/testing/selftests/bpf/prog_tests/cgroup_link.c b/tools/testing/selftests/bpf/prog_tests/cgroup_link.c
new file mode 100644
index 000000000000..6e04f8d1d15b
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/cgroup_link.c
@@ -0,0 +1,244 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+#include "cgroup_helpers.h"
+#include "test_cgroup_link.skel.h"
+
+static __u32 duration = 0;
+#define PING_CMD "ping -q -c1 -w1 127.0.0.1 > /dev/null"
+
+static struct test_cgroup_link *skel = NULL;
+
+int ping_and_check(int exp_calls, int exp_alt_calls)
+{
+ skel->bss->calls = 0;
+ skel->bss->alt_calls = 0;
+ CHECK_FAIL(system(PING_CMD));
+ if (CHECK(skel->bss->calls != exp_calls, "call_cnt",
+ "exp %d, got %d\n", exp_calls, skel->bss->calls))
+ return -EINVAL;
+ if (CHECK(skel->bss->alt_calls != exp_alt_calls, "alt_call_cnt",
+ "exp %d, got %d\n", exp_alt_calls, skel->bss->alt_calls))
+ return -EINVAL;
+ return 0;
+}
+
+void test_cgroup_link(void)
+{
+ struct {
+ const char *path;
+ int fd;
+ } cgs[] = {
+ { "/cg1" },
+ { "/cg1/cg2" },
+ { "/cg1/cg2/cg3" },
+ { "/cg1/cg2/cg3/cg4" },
+ };
+ int last_cg = ARRAY_SIZE(cgs) - 1, cg_nr = ARRAY_SIZE(cgs);
+ DECLARE_LIBBPF_OPTS(bpf_link_update_opts, link_upd_opts);
+ struct bpf_link *links[ARRAY_SIZE(cgs)] = {}, *tmp_link;
+ __u32 prog_ids[ARRAY_SIZE(cgs)], prog_cnt = 0, attach_flags;
+ int i = 0, err, prog_fd;
+ bool detach_legacy = false;
+
+ skel = test_cgroup_link__open_and_load();
+ if (CHECK(!skel, "skel_open_load", "failed to open/load skeleton\n"))
+ return;
+ prog_fd = bpf_program__fd(skel->progs.egress);
+
+ err = setup_cgroup_environment();
+ if (CHECK(err, "cg_init", "failed: %d\n", err))
+ goto cleanup;
+
+ for (i = 0; i < cg_nr; i++) {
+ cgs[i].fd = create_and_get_cgroup(cgs[i].path);
+ if (CHECK(cgs[i].fd < 0, "cg_create", "fail: %d\n", cgs[i].fd))
+ goto cleanup;
+ }
+
+ err = join_cgroup(cgs[last_cg].path);
+ if (CHECK(err, "cg_join", "fail: %d\n", err))
+ goto cleanup;
+
+ for (i = 0; i < cg_nr; i++) {
+ links[i] = bpf_program__attach_cgroup(skel->progs.egress,
+ cgs[i].fd);
+ if (CHECK(IS_ERR(links[i]), "cg_attach", "i: %d, err: %ld\n",
+ i, PTR_ERR(links[i])))
+ goto cleanup;
+ }
+
+ ping_and_check(cg_nr, 0);
+
+ /* query the number of effective progs and attach flags in root cg */
+ err = bpf_prog_query(cgs[0].fd, BPF_CGROUP_INET_EGRESS,
+ BPF_F_QUERY_EFFECTIVE, &attach_flags, NULL,
+ &prog_cnt);
+ CHECK_FAIL(err);
+ CHECK_FAIL(attach_flags != BPF_F_ALLOW_MULTI);
+ if (CHECK(prog_cnt != 1, "effect_cnt", "exp %d, got %d\n", 1, prog_cnt))
+ goto cleanup;
+
+ /* query the number of effective progs in last cg */
+ err = bpf_prog_query(cgs[last_cg].fd, BPF_CGROUP_INET_EGRESS,
+ BPF_F_QUERY_EFFECTIVE, NULL, NULL,
+ &prog_cnt);
+ CHECK_FAIL(err);
+ CHECK_FAIL(attach_flags != BPF_F_ALLOW_MULTI);
+ if (CHECK(prog_cnt != cg_nr, "effect_cnt", "exp %d, got %d\n",
+ cg_nr, prog_cnt))
+ goto cleanup;
+
+ /* query the effective prog IDs in last cg */
+ err = bpf_prog_query(cgs[last_cg].fd, BPF_CGROUP_INET_EGRESS,
+ BPF_F_QUERY_EFFECTIVE, &attach_flags,
+ prog_ids, &prog_cnt);
+ CHECK_FAIL(err);
+ CHECK_FAIL(attach_flags != BPF_F_ALLOW_MULTI);
+ if (CHECK(prog_cnt != cg_nr, "effect_cnt", "exp %d, got %d\n",
+ cg_nr, prog_cnt))
+ goto cleanup;
+ for (i = 1; i < prog_cnt; i++) {
+ CHECK(prog_ids[i - 1] != prog_ids[i], "prog_id_check",
+ "idx %d, prev id %d, cur id %d\n",
+ i, prog_ids[i - 1], prog_ids[i]);
+ }
+
+ /* detach bottom program and ping again */
+ bpf_link__destroy(links[last_cg]);
+ links[last_cg] = NULL;
+
+ ping_and_check(cg_nr - 1, 0);
+
+ /* mix in with non link-based multi-attachments */
+ err = bpf_prog_attach(prog_fd, cgs[last_cg].fd,
+ BPF_CGROUP_INET_EGRESS, BPF_F_ALLOW_MULTI);
+ if (CHECK(err, "cg_attach_legacy", "errno=%d\n", errno))
+ goto cleanup;
+ detach_legacy = true;
+
+ links[last_cg] = bpf_program__attach_cgroup(skel->progs.egress,
+ cgs[last_cg].fd);
+ if (CHECK(IS_ERR(links[last_cg]), "cg_attach", "err: %ld\n",
+ PTR_ERR(links[last_cg])))
+ goto cleanup;
+
+ ping_and_check(cg_nr + 1, 0);
+
+ /* detach link */
+ bpf_link__destroy(links[last_cg]);
+ links[last_cg] = NULL;
+
+ /* detach legacy */
+ err = bpf_prog_detach2(prog_fd, cgs[last_cg].fd, BPF_CGROUP_INET_EGRESS);
+ if (CHECK(err, "cg_detach_legacy", "errno=%d\n", errno))
+ goto cleanup;
+ detach_legacy = false;
+
+ /* attach legacy exclusive prog attachment */
+ err = bpf_prog_attach(prog_fd, cgs[last_cg].fd,
+ BPF_CGROUP_INET_EGRESS, 0);
+ if (CHECK(err, "cg_attach_exclusive", "errno=%d\n", errno))
+ goto cleanup;
+ detach_legacy = true;
+
+ /* attempt to mix in with multi-attach bpf_link */
+ tmp_link = bpf_program__attach_cgroup(skel->progs.egress,
+ cgs[last_cg].fd);
+ if (CHECK(!IS_ERR(tmp_link), "cg_attach_fail", "unexpected success!\n")) {
+ bpf_link__destroy(tmp_link);
+ goto cleanup;
+ }
+
+ ping_and_check(cg_nr, 0);
+
+ /* detach */
+ err = bpf_prog_detach2(prog_fd, cgs[last_cg].fd, BPF_CGROUP_INET_EGRESS);
+ if (CHECK(err, "cg_detach_legacy", "errno=%d\n", errno))
+ goto cleanup;
+ detach_legacy = false;
+
+ ping_and_check(cg_nr - 1, 0);
+
+ /* attach back link-based one */
+ links[last_cg] = bpf_program__attach_cgroup(skel->progs.egress,
+ cgs[last_cg].fd);
+ if (CHECK(IS_ERR(links[last_cg]), "cg_attach", "err: %ld\n",
+ PTR_ERR(links[last_cg])))
+ goto cleanup;
+
+ ping_and_check(cg_nr, 0);
+
+ /* check legacy exclusive prog can't be attached */
+ err = bpf_prog_attach(prog_fd, cgs[last_cg].fd,
+ BPF_CGROUP_INET_EGRESS, 0);
+ if (CHECK(!err, "cg_attach_exclusive", "unexpected success")) {
+ bpf_prog_detach2(prog_fd, cgs[last_cg].fd, BPF_CGROUP_INET_EGRESS);
+ goto cleanup;
+ }
+
+ /* replace BPF programs inside their links for all but first link */
+ for (i = 1; i < cg_nr; i++) {
+ err = bpf_link__update_program(links[i], skel->progs.egress_alt);
+ if (CHECK(err, "prog_upd", "link #%d\n", i))
+ goto cleanup;
+ }
+
+ ping_and_check(1, cg_nr - 1);
+
+ /* Attempt program update with wrong expected BPF program */
+ link_upd_opts.old_prog_fd = bpf_program__fd(skel->progs.egress_alt);
+ link_upd_opts.flags = BPF_F_REPLACE;
+ err = bpf_link_update(bpf_link__fd(links[0]),
+ bpf_program__fd(skel->progs.egress_alt),
+ &link_upd_opts);
+ if (CHECK(err == 0 || errno != EPERM, "prog_cmpxchg1",
+ "unexpectedly succeeded, err %d, errno %d\n", err, -errno))
+ goto cleanup;
+
+ /* Compare-exchange single link program from egress to egress_alt */
+ link_upd_opts.old_prog_fd = bpf_program__fd(skel->progs.egress);
+ link_upd_opts.flags = BPF_F_REPLACE;
+ err = bpf_link_update(bpf_link__fd(links[0]),
+ bpf_program__fd(skel->progs.egress_alt),
+ &link_upd_opts);
+ if (CHECK(err, "prog_cmpxchg2", "errno %d\n", -errno))
+ goto cleanup;
+
+ /* ping */
+ ping_and_check(0, cg_nr);
+
+ /* close cgroup FDs before detaching links */
+ for (i = 0; i < cg_nr; i++) {
+ if (cgs[i].fd > 0) {
+ close(cgs[i].fd);
+ cgs[i].fd = -1;
+ }
+ }
+
+ /* BPF programs should still get called */
+ ping_and_check(0, cg_nr);
+
+ /* leave cgroup and remove them, don't detach programs */
+ cleanup_cgroup_environment();
+
+ /* BPF programs should have been auto-detached */
+ ping_and_check(0, 0);
+
+cleanup:
+ if (detach_legacy)
+ bpf_prog_detach2(prog_fd, cgs[last_cg].fd,
+ BPF_CGROUP_INET_EGRESS);
+
+ for (i = 0; i < cg_nr; i++) {
+ if (!IS_ERR(links[i]))
+ bpf_link__destroy(links[i]);
+ }
+ test_cgroup_link__destroy(skel);
+
+ for (i = 0; i < cg_nr; i++) {
+ if (cgs[i].fd > 0)
+ close(cgs[i].fd);
+ }
+ cleanup_cgroup_environment();
+}
diff --git a/tools/testing/selftests/bpf/progs/test_cgroup_link.c b/tools/testing/selftests/bpf/progs/test_cgroup_link.c
new file mode 100644
index 000000000000..77e47b9e4446
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_cgroup_link.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2020 Facebook
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+int calls = 0;
+int alt_calls = 0;
+
+SEC("cgroup_skb/egress1")
+int egress(struct __sk_buff *skb)
+{
+ __sync_fetch_and_add(&calls, 1);
+ return 1;
+}
+
+SEC("cgroup_skb/egress2")
+int egress_alt(struct __sk_buff *skb)
+{
+ __sync_fetch_and_add(&alt_calls, 1);
+ return 1;
+}
+
+char _license[] SEC("license") = "GPL";
+
--
2.17.1
