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
  9struct inst {
 10	struct bpf_object *obj;
 11	struct bpf_link   *link_fentry;
 12	struct bpf_link   *link_fexit;
 13};
 14
 15static 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
 33static 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
 44void 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
115cleanup_extra:
116	bpf_object__close(obj);
117cleanup:
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}