check_mtu.c

  1// SPDX-License-Identifier: GPL-2.0
  2/* Copyright (c) 2020 Jesper Dangaard Brouer */
  3
  4#include <linux/if_link.h> /* before test_progs.h, avoid bpf_util.h redefines */
  5#include <test_progs.h>
  6#include "test_check_mtu.skel.h"
  7#include "network_helpers.h"
  8
  9#include <stdlib.h>
 10#include <inttypes.h>
 11
 12#define IFINDEX_LO 1
 13
 14static __u32 duration; /* Hint: needed for CHECK macro */
 15
 16static int read_mtu_device_lo(void)
 17{
 18	const char *filename = "/sys/class/net/lo/mtu";
 19	char buf[11] = {};
 20	int value, n, fd;
 21
 22	fd = open(filename, 0, O_RDONLY);
 23	if (fd == -1)
 24		return -1;
 25
 26	n = read(fd, buf, sizeof(buf));
 27	close(fd);
 28
 29	if (n == -1)
 30		return -2;
 31
 32	value = strtoimax(buf, NULL, 10);
 33	if (errno == ERANGE)
 34		return -3;
 35
 36	return value;
 37}
 38
 39static void test_check_mtu_xdp_attach(void)
 40{
 41	struct bpf_link_info link_info;
 42	__u32 link_info_len = sizeof(link_info);
 43	struct test_check_mtu *skel;
 44	struct bpf_program *prog;
 45	struct bpf_link *link;
 46	int err = 0;
 47	int fd;
 48
 49	skel = test_check_mtu__open_and_load();
 50	if (CHECK(!skel, "open and load skel", "failed"))
 51		return; /* Exit if e.g. helper unknown to kernel */
 52
 53	prog = skel->progs.xdp_use_helper_basic;
 54
 55	link = bpf_program__attach_xdp(prog, IFINDEX_LO);
 56	if (!ASSERT_OK_PTR(link, "link_attach"))
 57		goto out;
 58	skel->links.xdp_use_helper_basic = link;
 59
 60	memset(&link_info, 0, sizeof(link_info));
 61	fd = bpf_link__fd(link);
 62	err = bpf_link_get_info_by_fd(fd, &link_info, &link_info_len);
 63	if (CHECK(err, "link_info", "failed: %d\n", err))
 64		goto out;
 65
 66	CHECK(link_info.type != BPF_LINK_TYPE_XDP, "link_type",
 67	      "got %u != exp %u\n", link_info.type, BPF_LINK_TYPE_XDP);
 68	CHECK(link_info.xdp.ifindex != IFINDEX_LO, "link_ifindex",
 69	      "got %u != exp %u\n", link_info.xdp.ifindex, IFINDEX_LO);
 70
 71	err = bpf_link__detach(link);
 72	CHECK(err, "link_detach", "failed %d\n", err);
 73
 74out:
 75	test_check_mtu__destroy(skel);
 76}
 77
 78static void test_check_mtu_run_xdp(struct test_check_mtu *skel,
 79				   struct bpf_program *prog,
 80				   __u32 mtu_expect)
 81{
 82	int retval_expect = XDP_PASS;
 83	__u32 mtu_result = 0;
 84	char buf[256] = {};
 85	int err, prog_fd = bpf_program__fd(prog);
 86	LIBBPF_OPTS(bpf_test_run_opts, topts,
 87		.repeat = 1,
 88		.data_in = &pkt_v4,
 89		.data_size_in = sizeof(pkt_v4),
 90		.data_out = buf,
 91		.data_size_out = sizeof(buf),
 92	);
 93
 94	err = bpf_prog_test_run_opts(prog_fd, &topts);
 95	ASSERT_OK(err, "test_run");
 96	ASSERT_EQ(topts.retval, retval_expect, "retval");
 97
 98	/* Extract MTU that BPF-prog got */
 99	mtu_result = skel->bss->global_bpf_mtu_xdp;
100	ASSERT_EQ(mtu_result, mtu_expect, "MTU-compare-user");
101}
102
103
104static void test_check_mtu_xdp(__u32 mtu, __u32 ifindex)
105{
106	struct test_check_mtu *skel;
107	int err;
108
109	skel = test_check_mtu__open();
110	if (CHECK(!skel, "skel_open", "failed"))
111		return;
112
113	/* Update "constants" in BPF-prog *BEFORE* libbpf load */
114	skel->rodata->GLOBAL_USER_MTU = mtu;
115	skel->rodata->GLOBAL_USER_IFINDEX = ifindex;
116
117	err = test_check_mtu__load(skel);
118	if (CHECK(err, "skel_load", "failed: %d\n", err))
119		goto cleanup;
120
121	test_check_mtu_run_xdp(skel, skel->progs.xdp_use_helper, mtu);
122	test_check_mtu_run_xdp(skel, skel->progs.xdp_exceed_mtu, mtu);
123	test_check_mtu_run_xdp(skel, skel->progs.xdp_minus_delta, mtu);
124	test_check_mtu_run_xdp(skel, skel->progs.xdp_input_len, mtu);
125	test_check_mtu_run_xdp(skel, skel->progs.xdp_input_len_exceed, mtu);
126
127cleanup:
128	test_check_mtu__destroy(skel);
129}
130
131static void test_check_mtu_run_tc(struct test_check_mtu *skel,
132				  struct bpf_program *prog,
133				  __u32 mtu_expect)
134{
135	int retval_expect = BPF_OK;
136	__u32 mtu_result = 0;
137	char buf[256] = {};
138	int err, prog_fd = bpf_program__fd(prog);
139	LIBBPF_OPTS(bpf_test_run_opts, topts,
140		.data_in = &pkt_v4,
141		.data_size_in = sizeof(pkt_v4),
142		.data_out = buf,
143		.data_size_out = sizeof(buf),
144		.repeat = 1,
145	);
146
147	err = bpf_prog_test_run_opts(prog_fd, &topts);
148	ASSERT_OK(err, "test_run");
149	ASSERT_EQ(topts.retval, retval_expect, "retval");
150
151	/* Extract MTU that BPF-prog got */
152	mtu_result = skel->bss->global_bpf_mtu_tc;
153	ASSERT_EQ(mtu_result, mtu_expect, "MTU-compare-user");
154}
155
156static void test_chk_segs_flag(struct test_check_mtu *skel, __u32 mtu)
157{
158	int err, prog_fd = bpf_program__fd(skel->progs.tc_chk_segs_flag);
159	struct __sk_buff skb = {
160		.gso_size = 10,
161	};
162	LIBBPF_OPTS(bpf_test_run_opts, topts,
163		    .data_in = &pkt_v4,
164		    .data_size_in = sizeof(pkt_v4),
165		    .ctx_in = &skb,
166		    .ctx_size_in = sizeof(skb),
167	);
168
169	/* Lower the mtu to test the BPF_MTU_CHK_SEGS */
170	SYS_NOFAIL("ip link set dev lo mtu 10");
171	err = bpf_prog_test_run_opts(prog_fd, &topts);
172	SYS_NOFAIL("ip link set dev lo mtu %u", mtu);
173	ASSERT_OK(err, "test_run");
174	ASSERT_EQ(topts.retval, BPF_OK, "retval");
175}
176
177static void test_check_mtu_tc(__u32 mtu, __u32 ifindex)
178{
179	struct test_check_mtu *skel;
180	int err;
181
182	skel = test_check_mtu__open();
183	if (CHECK(!skel, "skel_open", "failed"))
184		return;
185
186	/* Update "constants" in BPF-prog *BEFORE* libbpf load */
187	skel->rodata->GLOBAL_USER_MTU = mtu;
188	skel->rodata->GLOBAL_USER_IFINDEX = ifindex;
189
190	err = test_check_mtu__load(skel);
191	if (CHECK(err, "skel_load", "failed: %d\n", err))
192		goto cleanup;
193
194	test_check_mtu_run_tc(skel, skel->progs.tc_use_helper, mtu);
195	test_check_mtu_run_tc(skel, skel->progs.tc_exceed_mtu, mtu);
196	test_check_mtu_run_tc(skel, skel->progs.tc_exceed_mtu_da, mtu);
197	test_check_mtu_run_tc(skel, skel->progs.tc_minus_delta, mtu);
198	test_check_mtu_run_tc(skel, skel->progs.tc_input_len, mtu);
199	test_check_mtu_run_tc(skel, skel->progs.tc_input_len_exceed, mtu);
200	test_chk_segs_flag(skel, mtu);
201cleanup:
202	test_check_mtu__destroy(skel);
203}
204
205void test_ns_check_mtu(void)
206{
207	int mtu_lo;
208
209	if (test__start_subtest("bpf_check_mtu XDP-attach"))
210		test_check_mtu_xdp_attach();
211
212	mtu_lo = read_mtu_device_lo();
213	if (CHECK(mtu_lo < 0, "reading MTU value", "failed (err:%d)", mtu_lo))
214		return;
215
216	if (test__start_subtest("bpf_check_mtu XDP-run"))
217		test_check_mtu_xdp(mtu_lo, 0);
218
219	if (test__start_subtest("bpf_check_mtu XDP-run ifindex-lookup"))
220		test_check_mtu_xdp(mtu_lo, IFINDEX_LO);
221
222	if (test__start_subtest("bpf_check_mtu TC-run"))
223		test_check_mtu_tc(mtu_lo, 0);
224
225	if (test__start_subtest("bpf_check_mtu TC-run ifindex-lookup"))
226		test_check_mtu_tc(mtu_lo, IFINDEX_LO);
227}