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, prog: skel->progs.xdp_use_helper, mtu_expect: mtu);
122 test_check_mtu_run_xdp(skel, prog: skel->progs.xdp_exceed_mtu, mtu_expect: mtu);
123 test_check_mtu_run_xdp(skel, prog: skel->progs.xdp_minus_delta, mtu_expect: mtu);
124 test_check_mtu_run_xdp(skel, prog: skel->progs.xdp_input_len, mtu_expect: mtu);
125 test_check_mtu_run_xdp(skel, prog: skel->progs.xdp_input_len_exceed, mtu_expect: 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, prog: skel->progs.tc_use_helper, mtu_expect: mtu);
195 test_check_mtu_run_tc(skel, prog: skel->progs.tc_exceed_mtu, mtu_expect: mtu);
196 test_check_mtu_run_tc(skel, prog: skel->progs.tc_exceed_mtu_da, mtu_expect: mtu);
197 test_check_mtu_run_tc(skel, prog: skel->progs.tc_minus_delta, mtu_expect: mtu);
198 test_check_mtu_run_tc(skel, prog: skel->progs.tc_input_len, mtu_expect: mtu);
199 test_check_mtu_run_tc(skel, prog: skel->progs.tc_input_len_exceed, mtu_expect: 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: mtu_lo, ifindex: 0);
218
219 if (test__start_subtest("bpf_check_mtu XDP-run ifindex-lookup"))
220 test_check_mtu_xdp(mtu: mtu_lo, IFINDEX_LO);
221
222 if (test__start_subtest("bpf_check_mtu TC-run"))
223 test_check_mtu_tc(mtu: mtu_lo, ifindex: 0);
224
225 if (test__start_subtest("bpf_check_mtu TC-run ifindex-lookup"))
226 test_check_mtu_tc(mtu: mtu_lo, IFINDEX_LO);
227}
228

source code of linux/tools/testing/selftests/bpf/prog_tests/check_mtu.c