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 <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200330030001.2312810-5-andriin@fb.com
This commit is contained in:
Andrii Nakryiko
Alexei Starovoitov
Родитель
cc4f864bb1
Коммит
7cccee42bf
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// SPDX-License-Identifier: GPL-2.0
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#include <test_progs.h>
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#include "cgroup_helpers.h"
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#include "test_cgroup_link.skel.h"
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static __u32 duration = 0;
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#define PING_CMD "ping -q -c1 -w1 127.0.0.1 > /dev/null"
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static struct test_cgroup_link *skel = NULL;
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int ping_and_check(int exp_calls, int exp_alt_calls)
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{
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skel->bss->calls = 0;
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skel->bss->alt_calls = 0;
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CHECK_FAIL(system(PING_CMD));
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if (CHECK(skel->bss->calls != exp_calls, "call_cnt",
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"exp %d, got %d\n", exp_calls, skel->bss->calls))
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return -EINVAL;
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if (CHECK(skel->bss->alt_calls != exp_alt_calls, "alt_call_cnt",
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"exp %d, got %d\n", exp_alt_calls, skel->bss->alt_calls))
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return -EINVAL;
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return 0;
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}
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void test_cgroup_link(void)
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{
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struct {
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const char *path;
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int fd;
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} cgs[] = {
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{ "/cg1" },
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{ "/cg1/cg2" },
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{ "/cg1/cg2/cg3" },
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{ "/cg1/cg2/cg3/cg4" },
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};
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int last_cg = ARRAY_SIZE(cgs) - 1, cg_nr = ARRAY_SIZE(cgs);
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DECLARE_LIBBPF_OPTS(bpf_link_update_opts, link_upd_opts);
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struct bpf_link *links[ARRAY_SIZE(cgs)] = {}, *tmp_link;
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__u32 prog_ids[ARRAY_SIZE(cgs)], prog_cnt = 0, attach_flags;
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int i = 0, err, prog_fd;
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bool detach_legacy = false;
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skel = test_cgroup_link__open_and_load();
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if (CHECK(!skel, "skel_open_load", "failed to open/load skeleton\n"))
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return;
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prog_fd = bpf_program__fd(skel->progs.egress);
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err = setup_cgroup_environment();
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if (CHECK(err, "cg_init", "failed: %d\n", err))
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goto cleanup;
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for (i = 0; i < cg_nr; i++) {
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cgs[i].fd = create_and_get_cgroup(cgs[i].path);
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if (CHECK(cgs[i].fd < 0, "cg_create", "fail: %d\n", cgs[i].fd))
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goto cleanup;
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}
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err = join_cgroup(cgs[last_cg].path);
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if (CHECK(err, "cg_join", "fail: %d\n", err))
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goto cleanup;
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for (i = 0; i < cg_nr; i++) {
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links[i] = bpf_program__attach_cgroup(skel->progs.egress,
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cgs[i].fd);
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if (CHECK(IS_ERR(links[i]), "cg_attach", "i: %d, err: %ld\n",
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i, PTR_ERR(links[i])))
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goto cleanup;
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}
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ping_and_check(cg_nr, 0);
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/* query the number of effective progs and attach flags in root cg */
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err = bpf_prog_query(cgs[0].fd, BPF_CGROUP_INET_EGRESS,
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BPF_F_QUERY_EFFECTIVE, &attach_flags, NULL,
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&prog_cnt);
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CHECK_FAIL(err);
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CHECK_FAIL(attach_flags != BPF_F_ALLOW_MULTI);
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if (CHECK(prog_cnt != 1, "effect_cnt", "exp %d, got %d\n", 1, prog_cnt))
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goto cleanup;
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/* query the number of effective progs in last cg */
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err = bpf_prog_query(cgs[last_cg].fd, BPF_CGROUP_INET_EGRESS,
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BPF_F_QUERY_EFFECTIVE, NULL, NULL,
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&prog_cnt);
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CHECK_FAIL(err);
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CHECK_FAIL(attach_flags != BPF_F_ALLOW_MULTI);
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if (CHECK(prog_cnt != cg_nr, "effect_cnt", "exp %d, got %d\n",
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cg_nr, prog_cnt))
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goto cleanup;
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/* query the effective prog IDs in last cg */
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err = bpf_prog_query(cgs[last_cg].fd, BPF_CGROUP_INET_EGRESS,
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BPF_F_QUERY_EFFECTIVE, &attach_flags,
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prog_ids, &prog_cnt);
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CHECK_FAIL(err);
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CHECK_FAIL(attach_flags != BPF_F_ALLOW_MULTI);
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if (CHECK(prog_cnt != cg_nr, "effect_cnt", "exp %d, got %d\n",
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cg_nr, prog_cnt))
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goto cleanup;
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for (i = 1; i < prog_cnt; i++) {
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CHECK(prog_ids[i - 1] != prog_ids[i], "prog_id_check",
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"idx %d, prev id %d, cur id %d\n",
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i, prog_ids[i - 1], prog_ids[i]);
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}
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/* detach bottom program and ping again */
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bpf_link__destroy(links[last_cg]);
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links[last_cg] = NULL;
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ping_and_check(cg_nr - 1, 0);
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/* mix in with non link-based multi-attachments */
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err = bpf_prog_attach(prog_fd, cgs[last_cg].fd,
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BPF_CGROUP_INET_EGRESS, BPF_F_ALLOW_MULTI);
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if (CHECK(err, "cg_attach_legacy", "errno=%d\n", errno))
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goto cleanup;
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detach_legacy = true;
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links[last_cg] = bpf_program__attach_cgroup(skel->progs.egress,
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cgs[last_cg].fd);
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if (CHECK(IS_ERR(links[last_cg]), "cg_attach", "err: %ld\n",
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PTR_ERR(links[last_cg])))
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goto cleanup;
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ping_and_check(cg_nr + 1, 0);
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/* detach link */
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bpf_link__destroy(links[last_cg]);
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links[last_cg] = NULL;
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/* detach legacy */
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err = bpf_prog_detach2(prog_fd, cgs[last_cg].fd, BPF_CGROUP_INET_EGRESS);
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if (CHECK(err, "cg_detach_legacy", "errno=%d\n", errno))
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goto cleanup;
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detach_legacy = false;
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/* attach legacy exclusive prog attachment */
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err = bpf_prog_attach(prog_fd, cgs[last_cg].fd,
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BPF_CGROUP_INET_EGRESS, 0);
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if (CHECK(err, "cg_attach_exclusive", "errno=%d\n", errno))
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goto cleanup;
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detach_legacy = true;
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/* attempt to mix in with multi-attach bpf_link */
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tmp_link = bpf_program__attach_cgroup(skel->progs.egress,
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cgs[last_cg].fd);
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if (CHECK(!IS_ERR(tmp_link), "cg_attach_fail", "unexpected success!\n")) {
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bpf_link__destroy(tmp_link);
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goto cleanup;
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}
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ping_and_check(cg_nr, 0);
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/* detach */
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err = bpf_prog_detach2(prog_fd, cgs[last_cg].fd, BPF_CGROUP_INET_EGRESS);
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if (CHECK(err, "cg_detach_legacy", "errno=%d\n", errno))
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goto cleanup;
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detach_legacy = false;
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ping_and_check(cg_nr - 1, 0);
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/* attach back link-based one */
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links[last_cg] = bpf_program__attach_cgroup(skel->progs.egress,
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cgs[last_cg].fd);
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if (CHECK(IS_ERR(links[last_cg]), "cg_attach", "err: %ld\n",
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PTR_ERR(links[last_cg])))
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goto cleanup;
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ping_and_check(cg_nr, 0);
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/* check legacy exclusive prog can't be attached */
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err = bpf_prog_attach(prog_fd, cgs[last_cg].fd,
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BPF_CGROUP_INET_EGRESS, 0);
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if (CHECK(!err, "cg_attach_exclusive", "unexpected success")) {
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bpf_prog_detach2(prog_fd, cgs[last_cg].fd, BPF_CGROUP_INET_EGRESS);
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goto cleanup;
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}
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/* replace BPF programs inside their links for all but first link */
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for (i = 1; i < cg_nr; i++) {
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err = bpf_link__update_program(links[i], skel->progs.egress_alt);
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if (CHECK(err, "prog_upd", "link #%d\n", i))
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goto cleanup;
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}
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ping_and_check(1, cg_nr - 1);
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/* Attempt program update with wrong expected BPF program */
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link_upd_opts.old_prog_fd = bpf_program__fd(skel->progs.egress_alt);
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link_upd_opts.flags = BPF_F_REPLACE;
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err = bpf_link_update(bpf_link__fd(links[0]),
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bpf_program__fd(skel->progs.egress_alt),
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&link_upd_opts);
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if (CHECK(err == 0 || errno != EPERM, "prog_cmpxchg1",
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"unexpectedly succeeded, err %d, errno %d\n", err, -errno))
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goto cleanup;
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/* Compare-exchange single link program from egress to egress_alt */
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link_upd_opts.old_prog_fd = bpf_program__fd(skel->progs.egress);
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link_upd_opts.flags = BPF_F_REPLACE;
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err = bpf_link_update(bpf_link__fd(links[0]),
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bpf_program__fd(skel->progs.egress_alt),
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&link_upd_opts);
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if (CHECK(err, "prog_cmpxchg2", "errno %d\n", -errno))
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goto cleanup;
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/* ping */
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ping_and_check(0, cg_nr);
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/* close cgroup FDs before detaching links */
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for (i = 0; i < cg_nr; i++) {
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if (cgs[i].fd > 0) {
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close(cgs[i].fd);
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cgs[i].fd = -1;
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}
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}
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/* BPF programs should still get called */
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ping_and_check(0, cg_nr);
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/* leave cgroup and remove them, don't detach programs */
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cleanup_cgroup_environment();
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/* BPF programs should have been auto-detached */
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ping_and_check(0, 0);
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cleanup:
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if (detach_legacy)
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bpf_prog_detach2(prog_fd, cgs[last_cg].fd,
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BPF_CGROUP_INET_EGRESS);
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for (i = 0; i < cg_nr; i++) {
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if (!IS_ERR(links[i]))
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bpf_link__destroy(links[i]);
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}
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test_cgroup_link__destroy(skel);
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for (i = 0; i < cg_nr; i++) {
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if (cgs[i].fd > 0)
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close(cgs[i].fd);
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}
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cleanup_cgroup_environment();
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}
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@ -0,0 +1,24 @@
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// SPDX-License-Identifier: GPL-2.0
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// Copyright (c) 2020 Facebook
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#include <linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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int calls = 0;
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int alt_calls = 0;
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SEC("cgroup_skb/egress1")
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int egress(struct __sk_buff *skb)
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{
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__sync_fetch_and_add(&calls, 1);
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return 1;
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}
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SEC("cgroup_skb/egress2")
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int egress_alt(struct __sk_buff *skb)
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{
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__sync_fetch_and_add(&alt_calls, 1);
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return 1;
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}
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char _license[] SEC("license") = "GPL";
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