1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2020 Facebook */
3 #include <uapi/linux/if_link.h>
4 #include <test_progs.h>
5 #include "test_xdp_link.skel.h"
6 
7 #define IFINDEX_LO 1
8 
9 void test_xdp_link(void)
10 {
11 	__u32 duration = 0, id1, id2, id0 = 0, prog_fd1, prog_fd2, err;
12 	DECLARE_LIBBPF_OPTS(bpf_xdp_set_link_opts, opts, .old_fd = -1);
13 	struct test_xdp_link *skel1 = NULL, *skel2 = NULL;
14 	struct bpf_link_info link_info;
15 	struct bpf_prog_info prog_info;
16 	struct bpf_link *link;
17 	__u32 link_info_len = sizeof(link_info);
18 	__u32 prog_info_len = sizeof(prog_info);
19 
20 	skel1 = test_xdp_link__open_and_load();
21 	if (CHECK(!skel1, "skel_load", "skeleton open and load failed\n"))
22 		goto cleanup;
23 	prog_fd1 = bpf_program__fd(skel1->progs.xdp_handler);
24 
25 	skel2 = test_xdp_link__open_and_load();
26 	if (CHECK(!skel2, "skel_load", "skeleton open and load failed\n"))
27 		goto cleanup;
28 	prog_fd2 = bpf_program__fd(skel2->progs.xdp_handler);
29 
30 	memset(&prog_info, 0, sizeof(prog_info));
31 	err = bpf_obj_get_info_by_fd(prog_fd1, &prog_info, &prog_info_len);
32 	if (CHECK(err, "fd_info1", "failed %d\n", -errno))
33 		goto cleanup;
34 	id1 = prog_info.id;
35 
36 	memset(&prog_info, 0, sizeof(prog_info));
37 	err = bpf_obj_get_info_by_fd(prog_fd2, &prog_info, &prog_info_len);
38 	if (CHECK(err, "fd_info2", "failed %d\n", -errno))
39 		goto cleanup;
40 	id2 = prog_info.id;
41 
42 	/* set initial prog attachment */
43 	err = bpf_set_link_xdp_fd_opts(IFINDEX_LO, prog_fd1, XDP_FLAGS_REPLACE, &opts);
44 	if (CHECK(err, "fd_attach", "initial prog attach failed: %d\n", err))
45 		goto cleanup;
46 
47 	/* validate prog ID */
48 	err = bpf_get_link_xdp_id(IFINDEX_LO, &id0, 0);
49 	CHECK(err || id0 != id1, "id1_check",
50 	      "loaded prog id %u != id1 %u, err %d", id0, id1, err);
51 
52 	/* BPF link is not allowed to replace prog attachment */
53 	link = bpf_program__attach_xdp(skel1->progs.xdp_handler, IFINDEX_LO);
54 	if (CHECK(!IS_ERR(link), "link_attach_fail", "unexpected success\n")) {
55 		bpf_link__destroy(link);
56 		/* best-effort detach prog */
57 		opts.old_fd = prog_fd1;
58 		bpf_set_link_xdp_fd_opts(IFINDEX_LO, -1, XDP_FLAGS_REPLACE, &opts);
59 		goto cleanup;
60 	}
61 
62 	/* detach BPF program */
63 	opts.old_fd = prog_fd1;
64 	err = bpf_set_link_xdp_fd_opts(IFINDEX_LO, -1, XDP_FLAGS_REPLACE, &opts);
65 	if (CHECK(err, "prog_detach", "failed %d\n", err))
66 		goto cleanup;
67 
68 	/* now BPF link should attach successfully */
69 	link = bpf_program__attach_xdp(skel1->progs.xdp_handler, IFINDEX_LO);
70 	if (CHECK(IS_ERR(link), "link_attach", "failed: %ld\n", PTR_ERR(link)))
71 		goto cleanup;
72 	skel1->links.xdp_handler = link;
73 
74 	/* validate prog ID */
75 	err = bpf_get_link_xdp_id(IFINDEX_LO, &id0, 0);
76 	if (CHECK(err || id0 != id1, "id1_check",
77 		  "loaded prog id %u != id1 %u, err %d", id0, id1, err))
78 		goto cleanup;
79 
80 	/* BPF prog attach is not allowed to replace BPF link */
81 	opts.old_fd = prog_fd1;
82 	err = bpf_set_link_xdp_fd_opts(IFINDEX_LO, prog_fd2, XDP_FLAGS_REPLACE, &opts);
83 	if (CHECK(!err, "prog_attach_fail", "unexpected success\n"))
84 		goto cleanup;
85 
86 	/* Can't force-update when BPF link is active */
87 	err = bpf_set_link_xdp_fd(IFINDEX_LO, prog_fd2, 0);
88 	if (CHECK(!err, "prog_update_fail", "unexpected success\n"))
89 		goto cleanup;
90 
91 	/* Can't force-detach when BPF link is active */
92 	err = bpf_set_link_xdp_fd(IFINDEX_LO, -1, 0);
93 	if (CHECK(!err, "prog_detach_fail", "unexpected success\n"))
94 		goto cleanup;
95 
96 	/* BPF link is not allowed to replace another BPF link */
97 	link = bpf_program__attach_xdp(skel2->progs.xdp_handler, IFINDEX_LO);
98 	if (CHECK(!IS_ERR(link), "link_attach_fail", "unexpected success\n")) {
99 		bpf_link__destroy(link);
100 		goto cleanup;
101 	}
102 
103 	bpf_link__destroy(skel1->links.xdp_handler);
104 	skel1->links.xdp_handler = NULL;
105 
106 	/* new link attach should succeed */
107 	link = bpf_program__attach_xdp(skel2->progs.xdp_handler, IFINDEX_LO);
108 	if (CHECK(IS_ERR(link), "link_attach", "failed: %ld\n", PTR_ERR(link)))
109 		goto cleanup;
110 	skel2->links.xdp_handler = link;
111 
112 	err = bpf_get_link_xdp_id(IFINDEX_LO, &id0, 0);
113 	if (CHECK(err || id0 != id2, "id2_check",
114 		  "loaded prog id %u != id2 %u, err %d", id0, id1, err))
115 		goto cleanup;
116 
117 	/* updating program under active BPF link works as expected */
118 	err = bpf_link__update_program(link, skel1->progs.xdp_handler);
119 	if (CHECK(err, "link_upd", "failed: %d\n", err))
120 		goto cleanup;
121 
122 	memset(&link_info, 0, sizeof(link_info));
123 	err = bpf_obj_get_info_by_fd(bpf_link__fd(link), &link_info, &link_info_len);
124 	if (CHECK(err, "link_info", "failed: %d\n", err))
125 		goto cleanup;
126 
127 	CHECK(link_info.type != BPF_LINK_TYPE_XDP, "link_type",
128 	      "got %u != exp %u\n", link_info.type, BPF_LINK_TYPE_XDP);
129 	CHECK(link_info.prog_id != id1, "link_prog_id",
130 	      "got %u != exp %u\n", link_info.prog_id, id1);
131 	CHECK(link_info.xdp.ifindex != IFINDEX_LO, "link_ifindex",
132 	      "got %u != exp %u\n", link_info.xdp.ifindex, IFINDEX_LO);
133 
134 	err = bpf_link__detach(link);
135 	if (CHECK(err, "link_detach", "failed %d\n", err))
136 		goto cleanup;
137 
138 	memset(&link_info, 0, sizeof(link_info));
139 	err = bpf_obj_get_info_by_fd(bpf_link__fd(link), &link_info, &link_info_len);
140 	if (CHECK(err, "link_info", "failed: %d\n", err))
141 		goto cleanup;
142 	CHECK(link_info.prog_id != id1, "link_prog_id",
143 	      "got %u != exp %u\n", link_info.prog_id, id1);
144 	/* ifindex should be zeroed out */
145 	CHECK(link_info.xdp.ifindex != 0, "link_ifindex",
146 	      "got %u != exp %u\n", link_info.xdp.ifindex, 0);
147 
148 cleanup:
149 	test_xdp_link__destroy(skel1);
150 	test_xdp_link__destroy(skel2);
151 }
152