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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
#include <vmlinux.h>
#include <bpf/bpf_tracing.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"
#include "cgrp_kfunc_common.h"
char _license[] SEC("license") = "GPL";
/* Prototype for all of the program trace events below:
*
* TRACE_EVENT(cgroup_mkdir,
* TP_PROTO(struct cgroup *cgrp, const char *path),
* TP_ARGS(cgrp, path)
*/
static struct __cgrps_kfunc_map_value *insert_lookup_cgrp(struct cgroup *cgrp)
{
int status;
status = cgrps_kfunc_map_insert(cgrp);
if (status)
return NULL;
return cgrps_kfunc_map_value_lookup(cgrp);
}
SEC("tp_btf/cgroup_mkdir")
__failure __msg("Possibly NULL pointer passed to trusted arg0")
int BPF_PROG(cgrp_kfunc_acquire_untrusted, struct cgroup *cgrp, const char *path)
{
struct cgroup *acquired;
struct __cgrps_kfunc_map_value *v;
v = insert_lookup_cgrp(cgrp);
if (!v)
return 0;
/* Can't invoke bpf_cgroup_acquire() on an untrusted pointer. */
acquired = bpf_cgroup_acquire(v->cgrp);
if (acquired)
bpf_cgroup_release(acquired);
return 0;
}
SEC("tp_btf/cgroup_mkdir")
__failure __msg("Possibly NULL pointer passed to trusted arg0")
int BPF_PROG(cgrp_kfunc_acquire_no_null_check, struct cgroup *cgrp, const char *path)
{
struct cgroup *acquired;
acquired = bpf_cgroup_acquire(cgrp);
/*
* Can't invoke bpf_cgroup_release() without checking the return value
* of bpf_cgroup_acquire().
*/
bpf_cgroup_release(acquired);
return 0;
}
SEC("tp_btf/cgroup_mkdir")
__failure __msg("arg#0 pointer type STRUCT cgroup must point")
int BPF_PROG(cgrp_kfunc_acquire_fp, struct cgroup *cgrp, const char *path)
{
struct cgroup *acquired, *stack_cgrp = (struct cgroup *)&path;
/* Can't invoke bpf_cgroup_acquire() on a random frame pointer. */
acquired = bpf_cgroup_acquire((struct cgroup *)&stack_cgrp);
if (acquired)
bpf_cgroup_release(acquired);
return 0;
}
SEC("kretprobe/cgroup_destroy_locked")
__failure __msg("calling kernel function bpf_cgroup_acquire is not allowed")
int BPF_PROG(cgrp_kfunc_acquire_unsafe_kretprobe, struct cgroup *cgrp)
{
struct cgroup *acquired;
/* Can't acquire an untrusted struct cgroup * pointer. */
acquired = bpf_cgroup_acquire(cgrp);
if (acquired)
bpf_cgroup_release(acquired);
return 0;
}
SEC("tp_btf/cgroup_mkdir")
__failure __msg("cgrp_kfunc_acquire_trusted_walked")
int BPF_PROG(cgrp_kfunc_acquire_trusted_walked, struct cgroup *cgrp, const char *path)
{
struct cgroup *acquired;
/* Can't invoke bpf_cgroup_acquire() on a pointer obtained from walking a trusted cgroup. */
acquired = bpf_cgroup_acquire(cgrp->old_dom_cgrp);
if (acquired)
bpf_cgroup_release(acquired);
return 0;
}
SEC("tp_btf/cgroup_mkdir")
__failure __msg("Possibly NULL pointer passed to trusted arg0")
int BPF_PROG(cgrp_kfunc_acquire_null, struct cgroup *cgrp, const char *path)
{
struct cgroup *acquired;
/* Can't invoke bpf_cgroup_acquire() on a NULL pointer. */
acquired = bpf_cgroup_acquire(NULL);
if (acquired)
bpf_cgroup_release(acquired);
return 0;
}
SEC("tp_btf/cgroup_mkdir")
__failure __msg("Unreleased reference")
int BPF_PROG(cgrp_kfunc_acquire_unreleased, struct cgroup *cgrp, const char *path)
{
struct cgroup *acquired;
acquired = bpf_cgroup_acquire(cgrp);
/* Acquired cgroup is never released. */
__sink(acquired);
return 0;
}
SEC("tp_btf/cgroup_mkdir")
__failure __msg("Unreleased reference")
int BPF_PROG(cgrp_kfunc_xchg_unreleased, struct cgroup *cgrp, const char *path)
{
struct cgroup *kptr;
struct __cgrps_kfunc_map_value *v;
v = insert_lookup_cgrp(cgrp);
if (!v)
return 0;
kptr = bpf_kptr_xchg(&v->cgrp, NULL);
if (!kptr)
return 0;
/* Kptr retrieved from map is never released. */
return 0;
}
SEC("tp_btf/cgroup_mkdir")
__failure __msg("must be referenced or trusted")
int BPF_PROG(cgrp_kfunc_rcu_get_release, struct cgroup *cgrp, const char *path)
{
struct cgroup *kptr;
struct __cgrps_kfunc_map_value *v;
v = insert_lookup_cgrp(cgrp);
if (!v)
return 0;
bpf_rcu_read_lock();
kptr = v->cgrp;
if (kptr)
/* Can't release a cgroup kptr stored in a map. */
bpf_cgroup_release(kptr);
bpf_rcu_read_unlock();
return 0;
}
SEC("tp_btf/cgroup_mkdir")
__failure __msg("Possibly NULL pointer passed to trusted arg0")
int BPF_PROG(cgrp_kfunc_release_untrusted, struct cgroup *cgrp, const char *path)
{
struct __cgrps_kfunc_map_value *v;
v = insert_lookup_cgrp(cgrp);
if (!v)
return 0;
/* Can't invoke bpf_cgroup_release() on an untrusted pointer. */
bpf_cgroup_release(v->cgrp);
return 0;
}
SEC("tp_btf/cgroup_mkdir")
__failure __msg("arg#0 pointer type STRUCT cgroup must point")
int BPF_PROG(cgrp_kfunc_release_fp, struct cgroup *cgrp, const char *path)
{
struct cgroup *acquired = (struct cgroup *)&path;
/* Cannot release random frame pointer. */
bpf_cgroup_release(acquired);
return 0;
}
SEC("tp_btf/cgroup_mkdir")
__failure __msg("Possibly NULL pointer passed to trusted arg0")
int BPF_PROG(cgrp_kfunc_release_null, struct cgroup *cgrp, const char *path)
{
struct __cgrps_kfunc_map_value local, *v;
long status;
struct cgroup *acquired, *old;
s32 id;
status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);
if (status)
return 0;
local.cgrp = NULL;
status = bpf_map_update_elem(&__cgrps_kfunc_map, &id, &local, BPF_NOEXIST);
if (status)
return status;
v = bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);
if (!v)
return -ENOENT;
acquired = bpf_cgroup_acquire(cgrp);
if (!acquired)
return -ENOENT;
old = bpf_kptr_xchg(&v->cgrp, acquired);
/* old cannot be passed to bpf_cgroup_release() without a NULL check. */
bpf_cgroup_release(old);
return 0;
}
SEC("tp_btf/cgroup_mkdir")
__failure __msg("release kernel function bpf_cgroup_release expects")
int BPF_PROG(cgrp_kfunc_release_unacquired, struct cgroup *cgrp, const char *path)
{
/* Cannot release trusted cgroup pointer which was not acquired. */
bpf_cgroup_release(cgrp);
return 0;
}
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