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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
#include "bpf_iter.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include "bpf_misc.h"
char _license[] SEC("license") = "GPL";
struct {
__uint(type, BPF_MAP_TYPE_CGRP_STORAGE);
__uint(map_flags, BPF_F_NO_PREALLOC);
__type(key, int);
__type(value, long);
} map_a SEC(".maps");
__u32 target_pid;
__u64 cgroup_id;
void bpf_rcu_read_lock(void) __ksym;
void bpf_rcu_read_unlock(void) __ksym;
SEC("?iter.s/cgroup")
int cgroup_iter(struct bpf_iter__cgroup *ctx)
{
struct seq_file *seq = ctx->meta->seq;
struct cgroup *cgrp = ctx->cgroup;
long *ptr;
if (cgrp == NULL)
return 0;
ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0,
BPF_LOCAL_STORAGE_GET_F_CREATE);
if (ptr)
cgroup_id = cgrp->kn->id;
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int no_rcu_lock(void *ctx)
{
struct task_struct *task;
struct cgroup *cgrp;
long *ptr;
task = bpf_get_current_task_btf();
if (task->pid != target_pid)
return 0;
/* task->cgroups is untrusted in sleepable prog outside of RCU CS */
cgrp = task->cgroups->dfl_cgrp;
ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0,
BPF_LOCAL_STORAGE_GET_F_CREATE);
if (ptr)
cgroup_id = cgrp->kn->id;
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int yes_rcu_lock(void *ctx)
{
struct task_struct *task;
struct cgroup *cgrp;
long *ptr;
task = bpf_get_current_task_btf();
if (task->pid != target_pid)
return 0;
bpf_rcu_read_lock();
cgrp = task->cgroups->dfl_cgrp;
/* cgrp is trusted under RCU CS */
ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, BPF_LOCAL_STORAGE_GET_F_CREATE);
if (ptr)
cgroup_id = cgrp->kn->id;
bpf_rcu_read_unlock();
return 0;
}
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