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 
14 static __u32 duration; /* Hint: needed for CHECK macro */
15 
16 static 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 
39 static 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 
74 out:
75 	test_check_mtu__destroy(skel);
76 }
77 
78 static 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 
104 static 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 
127 cleanup:
128 	test_check_mtu__destroy(skel);
129 }
130 
131 static 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 
156 
157 static void test_check_mtu_tc(__u32 mtu, __u32 ifindex)
158 {
159 	struct test_check_mtu *skel;
160 	int err;
161 
162 	skel = test_check_mtu__open();
163 	if (CHECK(!skel, "skel_open", "failed"))
164 		return;
165 
166 	/* Update "constants" in BPF-prog *BEFORE* libbpf load */
167 	skel->rodata->GLOBAL_USER_MTU = mtu;
168 	skel->rodata->GLOBAL_USER_IFINDEX = ifindex;
169 
170 	err = test_check_mtu__load(skel);
171 	if (CHECK(err, "skel_load", "failed: %d\n", err))
172 		goto cleanup;
173 
174 	test_check_mtu_run_tc(skel, skel->progs.tc_use_helper, mtu);
175 	test_check_mtu_run_tc(skel, skel->progs.tc_exceed_mtu, mtu);
176 	test_check_mtu_run_tc(skel, skel->progs.tc_exceed_mtu_da, mtu);
177 	test_check_mtu_run_tc(skel, skel->progs.tc_minus_delta, mtu);
178 	test_check_mtu_run_tc(skel, skel->progs.tc_input_len, mtu);
179 	test_check_mtu_run_tc(skel, skel->progs.tc_input_len_exceed, mtu);
180 cleanup:
181 	test_check_mtu__destroy(skel);
182 }
183 
184 void serial_test_check_mtu(void)
185 {
186 	int mtu_lo;
187 
188 	if (test__start_subtest("bpf_check_mtu XDP-attach"))
189 		test_check_mtu_xdp_attach();
190 
191 	mtu_lo = read_mtu_device_lo();
192 	if (CHECK(mtu_lo < 0, "reading MTU value", "failed (err:%d)", mtu_lo))
193 		return;
194 
195 	if (test__start_subtest("bpf_check_mtu XDP-run"))
196 		test_check_mtu_xdp(mtu_lo, 0);
197 
198 	if (test__start_subtest("bpf_check_mtu XDP-run ifindex-lookup"))
199 		test_check_mtu_xdp(mtu_lo, IFINDEX_LO);
200 
201 	if (test__start_subtest("bpf_check_mtu TC-run"))
202 		test_check_mtu_tc(mtu_lo, 0);
203 
204 	if (test__start_subtest("bpf_check_mtu TC-run ifindex-lookup"))
205 		test_check_mtu_tc(mtu_lo, IFINDEX_LO);
206 }
207