tools/testing/selftests/bpf/prog_tests/fexit_sleep.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (c) 2021 Facebook */
   3 #define _GNU_SOURCE
   4 #include <sched.h>
   5 #include <test_progs.h>
   6 #include <time.h>
   7 #include <sys/mman.h>
   8 #include <sys/syscall.h>
   9 #include "fexit_sleep.lskel.h"
  10
  11 static int do_sleep(void *skel)
  12 {
  13         struct fexit_sleep_lskel *fexit_skel = skel;
  14         struct timespec ts1 = { .tv_nsec = 1 };
  15         struct timespec ts2 = { .tv_sec = 10 };
  16
  17         fexit_skel->bss->pid = getpid();
  18         (void)syscall(__NR_nanosleep, &ts1, NULL);
  19         (void)syscall(__NR_nanosleep, &ts2, NULL);
  20         return 0;
  21 }
  22
  23 #define STACK_SIZE (1024 * 1024)
  24
  25 void test_fexit_sleep(void)
  26 {
  27         struct fexit_sleep_lskel *fexit_skel = NULL;
  28         int wstatus, duration = 0;
  29         pid_t cpid;
  30         char *child_stack = NULL;
  31         int err, fexit_cnt;
  32
  33         fexit_skel = fexit_sleep_lskel__open_and_load();
  34         if (CHECK(!fexit_skel, "fexit_skel_load", "fexit skeleton failed\n"))
  35                 goto cleanup;
  36
  37         err = fexit_sleep_lskel__attach(fexit_skel);
  38         if (CHECK(err, "fexit_attach", "fexit attach failed: %d\n", err))
  39                 goto cleanup;
  40
  41         child_stack = mmap(NULL, STACK_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE |
  42                            MAP_ANONYMOUS | MAP_STACK, -1, 0);
  43         if (!ASSERT_NEQ(child_stack, MAP_FAILED, "mmap"))
  44                 goto cleanup;
  45
  46         cpid = clone(do_sleep, child_stack + STACK_SIZE, CLONE_FILES | SIGCHLD, fexit_skel);
  47         if (CHECK(cpid == -1, "clone", "%s\n", strerror(errno)))
  48                 goto cleanup;
  49
  50         /* wait until first sys_nanosleep ends and second sys_nanosleep starts */
  51         while (READ_ONCE(fexit_skel->bss->fentry_cnt) != 2);
  52         fexit_cnt = READ_ONCE(fexit_skel->bss->fexit_cnt);
  53         if (CHECK(fexit_cnt != 1, "fexit_cnt", "%d", fexit_cnt))
  54                 goto cleanup;
  55
  56         /* close progs and detach them. That will trigger two nop5->jmp5 rewrites
  57          * in the trampolines to skip nanosleep_fexit prog.
  58          * The nanosleep_fentry prog will get detached first.
  59          * The nanosleep_fexit prog will get detached second.
  60          * Detaching will trigger freeing of both progs JITed images.
  61          * There will be two dying bpf_tramp_image-s, but only the initial
  62          * bpf_tramp_image (with both _fentry and _fexit progs will be stuck
  63          * waiting for percpu_ref_kill to confirm). The other one
  64          * will be freed quickly.
  65          */
  66         close(fexit_skel->progs.nanosleep_fentry.prog_fd);
  67         close(fexit_skel->progs.nanosleep_fexit.prog_fd);
  68         fexit_sleep_lskel__detach(fexit_skel);
  69
  70         /* kill the thread to unwind sys_nanosleep stack through the trampoline */
  71         kill(cpid, 9);
  72
  73         if (CHECK(waitpid(cpid, &wstatus, 0) == -1, "waitpid", "%s\n", strerror(errno)))
  74                 goto cleanup;
  75         if (CHECK(WEXITSTATUS(wstatus) != 0, "exitstatus", "failed"))
  76                 goto cleanup;
  77
  78         /* The bypassed nanosleep_fexit prog shouldn't have executed.
  79          * Unlike progs the maps were not freed and directly accessible.
  80          */
  81         fexit_cnt = READ_ONCE(fexit_skel->bss->fexit_cnt);
  82         if (CHECK(fexit_cnt != 1, "fexit_cnt", "%d", fexit_cnt))
  83                 goto cleanup;
  84
  85 cleanup:
  86         munmap(child_stack, STACK_SIZE);
  87         fexit_sleep_lskel__destroy(fexit_skel);
  88 }