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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include "bpf_tracing_net.h"
#include "bpf_misc.h"
char _license[] SEC("license") = "GPL";
struct {
__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
__uint(map_flags, BPF_F_NO_PREALLOC);
__type(key, int);
__type(value, long);
} map_a SEC(".maps");
__u32 user_data, key_serial, target_pid;
__u64 flags, task_storage_val, cgroup_id;
struct bpf_key *bpf_lookup_user_key(__u32 serial, __u64 flags) __ksym;
void bpf_key_put(struct bpf_key *key) __ksym;
void bpf_rcu_read_lock(void) __ksym;
void bpf_rcu_read_unlock(void) __ksym;
struct task_struct *bpf_task_acquire_not_zero(struct task_struct *p) __ksym;
void bpf_task_release(struct task_struct *p) __ksym;
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int get_cgroup_id(void *ctx)
{
struct task_struct *task;
struct css_set *cgroups;
task = bpf_get_current_task_btf();
if (task->pid != target_pid)
return 0;
/* simulate bpf_get_current_cgroup_id() helper */
bpf_rcu_read_lock();
cgroups = task->cgroups;
if (!cgroups)
goto unlock;
cgroup_id = cgroups->dfl_cgrp->kn->id;
unlock:
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int task_succ(void *ctx)
{
struct task_struct *task, *real_parent;
long init_val = 2;
long *ptr;
task = bpf_get_current_task_btf();
if (task->pid != target_pid)
return 0;
bpf_rcu_read_lock();
/* region including helper using rcu ptr real_parent */
real_parent = task->real_parent;
if (!real_parent)
goto out;
ptr = bpf_task_storage_get(&map_a, real_parent, &init_val,
BPF_LOCAL_STORAGE_GET_F_CREATE);
if (!ptr)
goto out;
ptr = bpf_task_storage_get(&map_a, real_parent, 0, 0);
if (!ptr)
goto out;
task_storage_val = *ptr;
out:
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int no_lock(void *ctx)
{
struct task_struct *task, *real_parent;
/* no bpf_rcu_read_lock(), old code still works */
task = bpf_get_current_task_btf();
real_parent = task->real_parent;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int two_regions(void *ctx)
{
struct task_struct *task, *real_parent;
/* two regions */
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
bpf_rcu_read_unlock();
bpf_rcu_read_lock();
real_parent = task->real_parent;
if (!real_parent)
goto out;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry/" SYS_PREFIX "sys_getpgid")
int non_sleepable_1(void *ctx)
{
struct task_struct *task, *real_parent;
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
real_parent = task->real_parent;
if (!real_parent)
goto out;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry/" SYS_PREFIX "sys_getpgid")
int non_sleepable_2(void *ctx)
{
struct task_struct *task, *real_parent;
bpf_rcu_read_lock();
task = bpf_get_current_task_btf();
bpf_rcu_read_unlock();
bpf_rcu_read_lock();
real_parent = task->real_parent;
if (!real_parent)
goto out;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int task_acquire(void *ctx)
{
struct task_struct *task, *real_parent, *gparent;
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
real_parent = task->real_parent;
if (!real_parent)
goto out;
/* rcu_ptr->rcu_field */
gparent = real_parent->real_parent;
if (!gparent)
goto out;
/* acquire a reference which can be used outside rcu read lock region */
gparent = bpf_task_acquire_not_zero(gparent);
if (!gparent)
/* Until we resolve the issues with using task->rcu_users, we
* expect bpf_task_acquire_not_zero() to return a NULL task.
* See the comment at the definition of
* bpf_task_acquire_not_zero() for more details.
*/
goto out;
(void)bpf_task_storage_get(&map_a, gparent, 0, 0);
bpf_task_release(gparent);
out:
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int miss_lock(void *ctx)
{
struct task_struct *task;
struct css_set *cgroups;
struct cgroup *dfl_cgrp;
/* missing bpf_rcu_read_lock() */
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
(void)bpf_task_storage_get(&map_a, task, 0, 0);
bpf_rcu_read_unlock();
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int miss_unlock(void *ctx)
{
struct task_struct *task;
struct css_set *cgroups;
struct cgroup *dfl_cgrp;
/* missing bpf_rcu_read_unlock() */
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
(void)bpf_task_storage_get(&map_a, task, 0, 0);
return 0;
}
SEC("?fentry/" SYS_PREFIX "sys_getpgid")
int non_sleepable_rcu_mismatch(void *ctx)
{
struct task_struct *task, *real_parent;
task = bpf_get_current_task_btf();
/* non-sleepable: missing bpf_rcu_read_unlock() in one path */
bpf_rcu_read_lock();
real_parent = task->real_parent;
if (!real_parent)
goto out;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
if (real_parent)
bpf_rcu_read_unlock();
out:
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int inproper_sleepable_helper(void *ctx)
{
struct task_struct *task, *real_parent;
struct pt_regs *regs;
__u32 value = 0;
void *ptr;
task = bpf_get_current_task_btf();
/* sleepable helper in rcu read lock region */
bpf_rcu_read_lock();
real_parent = task->real_parent;
if (!real_parent)
goto out;
regs = (struct pt_regs *)bpf_task_pt_regs(real_parent);
if (!regs)
goto out;
ptr = (void *)PT_REGS_IP(regs);
(void)bpf_copy_from_user_task(&value, sizeof(uint32_t), ptr, task, 0);
user_data = value;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
bpf_rcu_read_unlock();
return 0;
}
SEC("?lsm.s/bpf")
int BPF_PROG(inproper_sleepable_kfunc, int cmd, union bpf_attr *attr, unsigned int size)
{
struct bpf_key *bkey;
/* sleepable kfunc in rcu read lock region */
bpf_rcu_read_lock();
bkey = bpf_lookup_user_key(key_serial, flags);
bpf_rcu_read_unlock();
if (!bkey)
return -1;
bpf_key_put(bkey);
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int nested_rcu_region(void *ctx)
{
struct task_struct *task, *real_parent;
/* nested rcu read lock regions */
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
bpf_rcu_read_lock();
real_parent = task->real_parent;
if (!real_parent)
goto out;
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
out:
bpf_rcu_read_unlock();
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int task_untrusted_non_rcuptr(void *ctx)
{
struct task_struct *task, *group_leader;
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
/* the pointer group_leader marked as untrusted */
group_leader = task->real_parent->group_leader;
(void)bpf_task_storage_get(&map_a, group_leader, 0, 0);
bpf_rcu_read_unlock();
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
int task_untrusted_rcuptr(void *ctx)
{
struct task_struct *task, *real_parent;
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
real_parent = task->real_parent;
bpf_rcu_read_unlock();
/* helper use of rcu ptr outside the rcu read lock region */
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
return 0;
}
SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
int cross_rcu_region(void *ctx)
{
struct task_struct *task, *real_parent;
/* rcu ptr define/use in different regions */
task = bpf_get_current_task_btf();
bpf_rcu_read_lock();
real_parent = task->real_parent;
bpf_rcu_read_unlock();
bpf_rcu_read_lock();
(void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
bpf_rcu_read_unlock();
return 0;
}
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