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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");
__s32 target_pid;
__u64 cgroup_id;
int target_hid;
bool is_cgroup1;
struct cgroup *bpf_task_get_cgroup1(struct task_struct *task, int hierarchy_id) __ksym;
void bpf_cgroup_release(struct cgroup *cgrp) __ksym;
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 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;
}
static void __no_rcu_lock(struct cgroup *cgrp)
{
long *ptr;
/* Note that trace rcu is held in sleepable prog, so we can use
* bpf_cgrp_storage_get() in sleepable prog.
*/
ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0,
BPF_LOCAL_STORAGE_GET_F_CREATE);
if (ptr)
cgroup_id = cgrp->kn->id;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int cgrp1_no_rcu_lock(void *ctx)
{
struct task_struct *task;
struct cgroup *cgrp;
task = bpf_get_current_task_btf();
if (task->pid != target_pid)
return 0;
/* bpf_task_get_cgroup1 can work in sleepable prog */
cgrp = bpf_task_get_cgroup1(task, target_hid);
if (!cgrp)
return 0;
__no_rcu_lock(cgrp);
bpf_cgroup_release(cgrp);
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int no_rcu_lock(void *ctx)
{
struct task_struct *task;
task = bpf_get_current_task_btf();
if (task->pid != target_pid)
return 0;
/* task->cgroups is untrusted in sleepable prog outside of RCU CS */
__no_rcu_lock(task->cgroups->dfl_cgrp);
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;
if (is_cgroup1) {
bpf_rcu_read_lock();
cgrp = bpf_task_get_cgroup1(task, target_hid);
if (!cgrp) {
bpf_rcu_read_unlock();
return 0;
}
ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, BPF_LOCAL_STORAGE_GET_F_CREATE);
if (ptr)
cgroup_id = cgrp->kn->id;
bpf_cgroup_release(cgrp);
bpf_rcu_read_unlock();
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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