1 // SPDX-License-Identifier: GPL-2.0-only
2 #define _GNU_SOURCE
3 #include <sched.h>
4 #include <sys/prctl.h>
5 #include <test_progs.h>
6
7 #define MAX_TRAMP_PROGS 38
8
9 struct inst {
10 struct bpf_object *obj;
11 struct bpf_link *link_fentry;
12 struct bpf_link *link_fexit;
13 };
14
test_task_rename(void)15 static int test_task_rename(void)
16 {
17 int fd, duration = 0, err;
18 char buf[] = "test_overhead";
19
20 fd = open("/proc/self/comm", O_WRONLY|O_TRUNC);
21 if (CHECK(fd < 0, "open /proc", "err %d", errno))
22 return -1;
23 err = write(fd, buf, sizeof(buf));
24 if (err < 0) {
25 CHECK(err < 0, "task rename", "err %d", errno);
26 close(fd);
27 return -1;
28 }
29 close(fd);
30 return 0;
31 }
32
load(struct bpf_object * obj,const char * name)33 static struct bpf_link *load(struct bpf_object *obj, const char *name)
34 {
35 struct bpf_program *prog;
36 int duration = 0;
37
38 prog = bpf_object__find_program_by_title(obj, name);
39 if (CHECK(!prog, "find_probe", "prog '%s' not found\n", name))
40 return ERR_PTR(-EINVAL);
41 return bpf_program__attach_trace(prog);
42 }
43
test_trampoline_count(void)44 void test_trampoline_count(void)
45 {
46 const char *fentry_name = "fentry/__set_task_comm";
47 const char *fexit_name = "fexit/__set_task_comm";
48 const char *object = "test_trampoline_count.o";
49 struct inst inst[MAX_TRAMP_PROGS] = {};
50 int err, i = 0, duration = 0;
51 struct bpf_object *obj;
52 struct bpf_link *link;
53 char comm[16] = {};
54
55 /* attach 'allowed' trampoline programs */
56 for (i = 0; i < MAX_TRAMP_PROGS; i++) {
57 obj = bpf_object__open_file(object, NULL);
58 if (!ASSERT_OK_PTR(obj, "obj_open_file")) {
59 obj = NULL;
60 goto cleanup;
61 }
62
63 err = bpf_object__load(obj);
64 if (CHECK(err, "obj_load", "err %d\n", err))
65 goto cleanup;
66 inst[i].obj = obj;
67 obj = NULL;
68
69 if (rand() % 2) {
70 link = load(inst[i].obj, fentry_name);
71 if (!ASSERT_OK_PTR(link, "attach_prog")) {
72 link = NULL;
73 goto cleanup;
74 }
75 inst[i].link_fentry = link;
76 } else {
77 link = load(inst[i].obj, fexit_name);
78 if (!ASSERT_OK_PTR(link, "attach_prog")) {
79 link = NULL;
80 goto cleanup;
81 }
82 inst[i].link_fexit = link;
83 }
84 }
85
86 /* and try 1 extra.. */
87 obj = bpf_object__open_file(object, NULL);
88 if (!ASSERT_OK_PTR(obj, "obj_open_file")) {
89 obj = NULL;
90 goto cleanup;
91 }
92
93 err = bpf_object__load(obj);
94 if (CHECK(err, "obj_load", "err %d\n", err))
95 goto cleanup_extra;
96
97 /* ..that needs to fail */
98 link = load(obj, fentry_name);
99 err = libbpf_get_error(link);
100 if (!ASSERT_ERR_PTR(link, "cannot attach over the limit")) {
101 bpf_link__destroy(link);
102 goto cleanup_extra;
103 }
104
105 /* with E2BIG error */
106 ASSERT_EQ(err, -E2BIG, "proper error check");
107 ASSERT_EQ(link, NULL, "ptr_is_null");
108
109 /* and finaly execute the probe */
110 if (CHECK_FAIL(prctl(PR_GET_NAME, comm, 0L, 0L, 0L)))
111 goto cleanup_extra;
112 CHECK_FAIL(test_task_rename());
113 CHECK_FAIL(prctl(PR_SET_NAME, comm, 0L, 0L, 0L));
114
115 cleanup_extra:
116 bpf_object__close(obj);
117 cleanup:
118 if (i >= MAX_TRAMP_PROGS)
119 i = MAX_TRAMP_PROGS - 1;
120 for (; i >= 0; i--) {
121 bpf_link__destroy(inst[i].link_fentry);
122 bpf_link__destroy(inst[i].link_fexit);
123 bpf_object__close(inst[i].obj);
124 }
125 }
126
