From 7cccee42bf76efc9de69fa2e5b8dbe58bfc8ecdf Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sun, 29 Mar 2020 20:00:01 -0700 Subject: [PATCH] selftests/bpf: Test FD-based cgroup attachment 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 Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200330030001.2312810-5-andriin@fb.com --- .../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 +#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 +#include + +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"; + -- 2.30.2