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1// SPDX-License-Identifier: GPL-2.02/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */3 4#include "bpf_iter.h"5#include <bpf/bpf_helpers.h>6#include <bpf/bpf_tracing.h>7#include "bpf_misc.h"8 9char _license[] SEC("license") = "GPL";10 11struct {12 __uint(type, BPF_MAP_TYPE_CGRP_STORAGE);13 __uint(map_flags, BPF_F_NO_PREALLOC);14 __type(key, int);15 __type(value, long);16} map_a SEC(".maps");17 18__s32 target_pid;19__u64 cgroup_id;20int target_hid;21bool is_cgroup1;22 23struct cgroup *bpf_task_get_cgroup1(struct task_struct *task, int hierarchy_id) __ksym;24void bpf_cgroup_release(struct cgroup *cgrp) __ksym;25void bpf_rcu_read_lock(void) __ksym;26void bpf_rcu_read_unlock(void) __ksym;27 28SEC("?iter.s/cgroup")29int cgroup_iter(struct bpf_iter__cgroup *ctx)30{31 struct cgroup *cgrp = ctx->cgroup;32 long *ptr;33 34 if (cgrp == NULL)35 return 0;36 37 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0,38 BPF_LOCAL_STORAGE_GET_F_CREATE);39 if (ptr)40 cgroup_id = cgrp->kn->id;41 return 0;42}43 44static void __no_rcu_lock(struct cgroup *cgrp)45{46 long *ptr;47 48 /* Note that trace rcu is held in sleepable prog, so we can use49 * bpf_cgrp_storage_get() in sleepable prog.50 */51 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0,52 BPF_LOCAL_STORAGE_GET_F_CREATE);53 if (ptr)54 cgroup_id = cgrp->kn->id;55}56 57SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")58int cgrp1_no_rcu_lock(void *ctx)59{60 struct task_struct *task;61 struct cgroup *cgrp;62 63 task = bpf_get_current_task_btf();64 if (task->pid != target_pid)65 return 0;66 67 /* bpf_task_get_cgroup1 can work in sleepable prog */68 cgrp = bpf_task_get_cgroup1(task, target_hid);69 if (!cgrp)70 return 0;71 72 __no_rcu_lock(cgrp);73 bpf_cgroup_release(cgrp);74 return 0;75}76 77SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")78int no_rcu_lock(void *ctx)79{80 struct task_struct *task;81 82 task = bpf_get_current_task_btf();83 if (task->pid != target_pid)84 return 0;85 86 /* task->cgroups is untrusted in sleepable prog outside of RCU CS */87 __no_rcu_lock(task->cgroups->dfl_cgrp);88 return 0;89}90 91SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")92int yes_rcu_lock(void *ctx)93{94 struct task_struct *task;95 struct cgroup *cgrp;96 long *ptr;97 98 task = bpf_get_current_task_btf();99 if (task->pid != target_pid)100 return 0;101 102 if (is_cgroup1) {103 bpf_rcu_read_lock();104 cgrp = bpf_task_get_cgroup1(task, target_hid);105 if (!cgrp) {106 bpf_rcu_read_unlock();107 return 0;108 }109 110 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, BPF_LOCAL_STORAGE_GET_F_CREATE);111 if (ptr)112 cgroup_id = cgrp->kn->id;113 bpf_cgroup_release(cgrp);114 bpf_rcu_read_unlock();115 return 0;116 }117 118 bpf_rcu_read_lock();119 cgrp = task->cgroups->dfl_cgrp;120 /* cgrp is trusted under RCU CS */121 ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, BPF_LOCAL_STORAGE_GET_F_CREATE);122 if (ptr)123 cgroup_id = cgrp->kn->id;124 bpf_rcu_read_unlock();125 return 0;126}127