1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2023 Red Hat, Inc. */
3 #include <test_progs.h>
4 #include "fentry_recursive.skel.h"
5 #include "fentry_recursive_target.skel.h"
6 #include <bpf/btf.h>
7 #include "bpf/libbpf_internal.h"
8
9 /* Test recursive attachment of tracing progs with more than one nesting level
10 * is not possible. Create a chain of attachment, verify that the last prog
11 * will fail. Depending on the arguments, following cases are tested:
12 *
13 * - Recursive loading of tracing progs, without attaching (attach = false,
14 * detach = false). The chain looks like this:
15 * load target
16 * load fentry1 -> target
17 * load fentry2 -> fentry1 (fail)
18 *
19 * - Recursive attach of tracing progs (attach = true, detach = false). The
20 * chain looks like this:
21 * load target
22 * load fentry1 -> target
23 * attach fentry1 -> target
24 * load fentry2 -> fentry1 (fail)
25 *
26 * - Recursive attach and detach of tracing progs (attach = true, detach =
27 * true). This validates that attach_tracing_prog flag will be set throughout
28 * the whole lifecycle of an fentry prog, independently from whether it's
29 * detached. The chain looks like this:
30 * load target
31 * load fentry1 -> target
32 * attach fentry1 -> target
33 * detach fentry1
34 * load fentry2 -> fentry1 (fail)
35 */
36 static void test_recursive_fentry_chain(bool attach, bool detach)
37 {
38 struct fentry_recursive_target *target_skel = NULL;
39 struct fentry_recursive *tracing_chain[2] = {};
40 struct bpf_program *prog;
41 int prev_fd, err;
42
43 target_skel = fentry_recursive_target__open_and_load();
44 if (!ASSERT_OK_PTR(target_skel, "fentry_recursive_target__open_and_load"))
45 return;
46
47 /* Create an attachment chain with two fentry progs */
48 for (int i = 0; i < 2; i++) {
49 tracing_chain[i] = fentry_recursive__open();
50 if (!ASSERT_OK_PTR(tracing_chain[i], "fentry_recursive__open"))
51 goto close_prog;
52
53 /* The first prog in the chain is going to be attached to the target
54 * fentry program, the second one to the previous in the chain.
55 */
56 prog = tracing_chain[i]->progs.recursive_attach;
57 if (i == 0) {
58 prev_fd = bpf_program__fd(target_skel->progs.test1);
59 err = bpf_program__set_attach_target(prog, prev_fd, "test1");
60 } else {
61 prev_fd = bpf_program__fd(tracing_chain[i-1]->progs.recursive_attach);
62 err = bpf_program__set_attach_target(prog, prev_fd, "recursive_attach");
63 }
64
65 if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
66 goto close_prog;
67
68 err = fentry_recursive__load(tracing_chain[i]);
69 /* The first attach should succeed, the second fail */
70 if (i == 0) {
71 if (!ASSERT_OK(err, "fentry_recursive__load"))
72 goto close_prog;
73
74 if (attach) {
75 err = fentry_recursive__attach(tracing_chain[i]);
76 if (!ASSERT_OK(err, "fentry_recursive__attach"))
77 goto close_prog;
78 }
79
80 if (detach) {
81 /* Flag attach_tracing_prog should still be set, preventing
82 * attachment of the following prog.
83 */
84 fentry_recursive__detach(tracing_chain[i]);
85 }
86 } else {
87 if (!ASSERT_ERR(err, "fentry_recursive__load"))
88 goto close_prog;
89 }
90 }
91
92 close_prog:
93 fentry_recursive_target__destroy(target_skel);
94 for (int i = 0; i < 2; i++) {
95 fentry_recursive__destroy(tracing_chain[i]);
96 }
97 }
98
99 void test_recursive_fentry(void)
100 {
101 if (test__start_subtest("attach"))
102 test_recursive_fentry_chain(true, false);
103 if (test__start_subtest("load"))
104 test_recursive_fentry_chain(false, false);
105 if (test__start_subtest("detach"))
106 test_recursive_fentry_chain(true, true);
107 }
108
109 /* Test that a tracing prog reattachment (when we land in
110 * "prog->aux->dst_trampoline and tgt_prog is NULL" branch in
111 * bpf_tracing_prog_attach) does not lead to a crash due to missing attach_btf
112 */
113 void test_fentry_attach_btf_presence(void)
114 {
115 struct fentry_recursive_target *target_skel = NULL;
116 struct fentry_recursive *tracing_skel = NULL;
117 struct bpf_program *prog;
118 int err, link_fd, tgt_prog_fd;
119
120 target_skel = fentry_recursive_target__open_and_load();
121 if (!ASSERT_OK_PTR(target_skel, "fentry_recursive_target__open_and_load"))
122 goto close_prog;
123
124 tracing_skel = fentry_recursive__open();
125 if (!ASSERT_OK_PTR(tracing_skel, "fentry_recursive__open"))
126 goto close_prog;
127
128 prog = tracing_skel->progs.recursive_attach;
129 tgt_prog_fd = bpf_program__fd(target_skel->progs.fentry_target);
130 err = bpf_program__set_attach_target(prog, tgt_prog_fd, "fentry_target");
131 if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
132 goto close_prog;
133
134 err = fentry_recursive__load(tracing_skel);
135 if (!ASSERT_OK(err, "fentry_recursive__load"))
136 goto close_prog;
137
138 tgt_prog_fd = bpf_program__fd(tracing_skel->progs.recursive_attach);
139 link_fd = bpf_link_create(tgt_prog_fd, 0, BPF_TRACE_FENTRY, NULL);
140 if (!ASSERT_GE(link_fd, 0, "link_fd"))
141 goto close_prog;
142
143 fentry_recursive__detach(tracing_skel);
144
145 err = fentry_recursive__attach(tracing_skel);
146 ASSERT_ERR(err, "fentry_recursive__attach");
147
148 close_prog:
149 fentry_recursive_target__destroy(target_skel);
150 fentry_recursive__destroy(tracing_skel);
151 }
152
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