tools/testing/selftests/bpf/progs/iters_task_failure.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (C) 2023 Chuyi Zhou <[email protected]> */
   3
   4 #include "vmlinux.h"
   5 #include <bpf/bpf_helpers.h>
   6 #include <bpf/bpf_tracing.h>
   7 #include "bpf_misc.h"
   8 #include "bpf_experimental.h"
   9
  10 char _license[] SEC("license") = "GPL";
  11
  12 struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
  13 void bpf_cgroup_release(struct cgroup *p) __ksym;
  14 void bpf_rcu_read_lock(void) __ksym;
  15 void bpf_rcu_read_unlock(void) __ksym;
  16
  17 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
  18 __failure __msg("expected an RCU CS when using bpf_iter_task_next")
  19 int BPF_PROG(iter_tasks_without_lock)
  20 {
  21         struct task_struct *pos;
  22
  23         bpf_for_each(task, pos, NULL, BPF_TASK_ITER_ALL_PROCS) {
  24
  25         }
  26         return 0;
  27 }
  28
  29 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
  30 __failure __msg("expected an RCU CS when using bpf_iter_css_next")
  31 int BPF_PROG(iter_css_without_lock)
  32 {
  33         u64 cg_id = bpf_get_current_cgroup_id();
  34         struct cgroup *cgrp = bpf_cgroup_from_id(cg_id);
  35         struct cgroup_subsys_state *root_css, *pos;
  36
  37         if (!cgrp)
  38                 return 0;
  39         root_css = &cgrp->self;
  40
  41         bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_POST) {
  42
  43         }
  44         bpf_cgroup_release(cgrp);
  45         return 0;
  46 }
  47
  48 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
  49 __failure __msg("expected an RCU CS when using bpf_iter_task_next")
  50 int BPF_PROG(iter_tasks_lock_and_unlock)
  51 {
  52         struct task_struct *pos;
  53
  54         bpf_rcu_read_lock();
  55         bpf_for_each(task, pos, NULL, BPF_TASK_ITER_ALL_PROCS) {
  56                 bpf_rcu_read_unlock();
  57
  58                 bpf_rcu_read_lock();
  59         }
  60         bpf_rcu_read_unlock();
  61         return 0;
  62 }
  63
  64 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
  65 __failure __msg("expected an RCU CS when using bpf_iter_css_next")
  66 int BPF_PROG(iter_css_lock_and_unlock)
  67 {
  68         u64 cg_id = bpf_get_current_cgroup_id();
  69         struct cgroup *cgrp = bpf_cgroup_from_id(cg_id);
  70         struct cgroup_subsys_state *root_css, *pos;
  71
  72         if (!cgrp)
  73                 return 0;
  74         root_css = &cgrp->self;
  75
  76         bpf_rcu_read_lock();
  77         bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_POST) {
  78                 bpf_rcu_read_unlock();
  79
  80                 bpf_rcu_read_lock();
  81         }
  82         bpf_rcu_read_unlock();
  83         bpf_cgroup_release(cgrp);
  84         return 0;
  85 }
  86
  87 SEC("?fentry/" SYS_PREFIX "sys_getpgid")
  88 __failure __msg("css_task_iter is only allowed in bpf_lsm, bpf_iter and sleepable progs")
  89 int BPF_PROG(iter_css_task_for_each)
  90 {
  91         u64 cg_id = bpf_get_current_cgroup_id();
  92         struct cgroup *cgrp = bpf_cgroup_from_id(cg_id);
  93         struct cgroup_subsys_state *css;
  94         struct task_struct *task;
  95
  96         if (cgrp == NULL)
  97                 return 0;
  98         css = &cgrp->self;
  99
 100         bpf_for_each(css_task, task, css, CSS_TASK_ITER_PROCS) {
 101
 102         }
 103         bpf_cgroup_release(cgrp);
 104         return 0;
 105 }