LXR linux/tools/testing/selftests/bpf/prog_tests/trampoline

   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}
 126