1 // SPDX-License-Identifier: GPL-2.0 2 /* Copyright (C) 2023 Chuyi Zhou <zhouchuyi@bytedance.com> */ 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 } 106