303 lines
7.2 KiB
C
303 lines
7.2 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
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#include <vmlinux.h>
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#include <bpf/bpf_tracing.h>
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#include <bpf/bpf_helpers.h>
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#include "bpf_misc.h"
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#include "task_kfunc_common.h"
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char _license[] SEC("license") = "GPL";
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/* Prototype for all of the program trace events below:
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*
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* TRACE_EVENT(task_newtask,
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* TP_PROTO(struct task_struct *p, u64 clone_flags)
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*/
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static struct __tasks_kfunc_map_value *insert_lookup_task(struct task_struct *task)
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{
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int status;
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status = tasks_kfunc_map_insert(task);
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if (status)
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return NULL;
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return tasks_kfunc_map_value_lookup(task);
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}
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SEC("tp_btf/task_newtask")
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__failure __msg("Possibly NULL pointer passed to trusted arg0")
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int BPF_PROG(task_kfunc_acquire_untrusted, struct task_struct *task, u64 clone_flags)
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{
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struct task_struct *acquired;
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struct __tasks_kfunc_map_value *v;
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v = insert_lookup_task(task);
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if (!v)
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return 0;
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/* Can't invoke bpf_task_acquire() on an untrusted pointer. */
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acquired = bpf_task_acquire(v->task);
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bpf_task_release(acquired);
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return 0;
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}
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SEC("tp_btf/task_newtask")
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__failure __msg("arg#0 pointer type STRUCT task_struct must point")
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int BPF_PROG(task_kfunc_acquire_fp, struct task_struct *task, u64 clone_flags)
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{
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struct task_struct *acquired, *stack_task = (struct task_struct *)&clone_flags;
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/* Can't invoke bpf_task_acquire() on a random frame pointer. */
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acquired = bpf_task_acquire((struct task_struct *)&stack_task);
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bpf_task_release(acquired);
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return 0;
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}
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SEC("kretprobe/free_task")
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__failure __msg("reg type unsupported for arg#0 function")
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int BPF_PROG(task_kfunc_acquire_unsafe_kretprobe, struct task_struct *task, u64 clone_flags)
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{
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struct task_struct *acquired;
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acquired = bpf_task_acquire(task);
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/* Can't release a bpf_task_acquire()'d task without a NULL check. */
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bpf_task_release(acquired);
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return 0;
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}
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SEC("tp_btf/task_newtask")
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__failure __msg("R1 must be referenced or trusted")
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int BPF_PROG(task_kfunc_acquire_trusted_walked, struct task_struct *task, u64 clone_flags)
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{
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struct task_struct *acquired;
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/* Can't invoke bpf_task_acquire() on a trusted pointer obtained from walking a struct. */
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acquired = bpf_task_acquire(task->group_leader);
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bpf_task_release(acquired);
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return 0;
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}
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SEC("tp_btf/task_newtask")
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__failure __msg("Possibly NULL pointer passed to trusted arg0")
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int BPF_PROG(task_kfunc_acquire_null, struct task_struct *task, u64 clone_flags)
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{
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struct task_struct *acquired;
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/* Can't invoke bpf_task_acquire() on a NULL pointer. */
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acquired = bpf_task_acquire(NULL);
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if (!acquired)
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return 0;
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bpf_task_release(acquired);
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return 0;
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}
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SEC("tp_btf/task_newtask")
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__failure __msg("Unreleased reference")
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int BPF_PROG(task_kfunc_acquire_unreleased, struct task_struct *task, u64 clone_flags)
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{
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struct task_struct *acquired;
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acquired = bpf_task_acquire(task);
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/* Acquired task is never released. */
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return 0;
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}
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SEC("tp_btf/task_newtask")
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__failure __msg("arg#0 expected pointer to map value")
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int BPF_PROG(task_kfunc_get_non_kptr_param, struct task_struct *task, u64 clone_flags)
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{
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struct task_struct *kptr;
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/* Cannot use bpf_task_kptr_get() on a non-kptr, even on a valid task. */
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kptr = bpf_task_kptr_get(&task);
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if (!kptr)
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return 0;
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bpf_task_release(kptr);
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return 0;
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}
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SEC("tp_btf/task_newtask")
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__failure __msg("arg#0 expected pointer to map value")
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int BPF_PROG(task_kfunc_get_non_kptr_acquired, struct task_struct *task, u64 clone_flags)
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{
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struct task_struct *kptr, *acquired;
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acquired = bpf_task_acquire(task);
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/* Cannot use bpf_task_kptr_get() on a non-kptr, even if it was acquired. */
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kptr = bpf_task_kptr_get(&acquired);
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bpf_task_release(acquired);
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if (!kptr)
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return 0;
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bpf_task_release(kptr);
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return 0;
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}
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SEC("tp_btf/task_newtask")
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__failure __msg("arg#0 expected pointer to map value")
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int BPF_PROG(task_kfunc_get_null, struct task_struct *task, u64 clone_flags)
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{
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struct task_struct *kptr;
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/* Cannot use bpf_task_kptr_get() on a NULL pointer. */
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kptr = bpf_task_kptr_get(NULL);
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if (!kptr)
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return 0;
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bpf_task_release(kptr);
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return 0;
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}
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SEC("tp_btf/task_newtask")
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__failure __msg("Unreleased reference")
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int BPF_PROG(task_kfunc_xchg_unreleased, struct task_struct *task, u64 clone_flags)
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{
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struct task_struct *kptr;
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struct __tasks_kfunc_map_value *v;
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v = insert_lookup_task(task);
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if (!v)
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return 0;
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kptr = bpf_kptr_xchg(&v->task, NULL);
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if (!kptr)
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return 0;
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/* Kptr retrieved from map is never released. */
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return 0;
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}
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SEC("tp_btf/task_newtask")
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__failure __msg("Unreleased reference")
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int BPF_PROG(task_kfunc_get_unreleased, struct task_struct *task, u64 clone_flags)
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{
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struct task_struct *kptr;
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struct __tasks_kfunc_map_value *v;
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v = insert_lookup_task(task);
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if (!v)
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return 0;
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kptr = bpf_task_kptr_get(&v->task);
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if (!kptr)
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return 0;
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/* Kptr acquired above is never released. */
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return 0;
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}
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SEC("tp_btf/task_newtask")
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__failure __msg("arg#0 is untrusted_ptr_or_null_ expected ptr_ or socket")
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int BPF_PROG(task_kfunc_release_untrusted, struct task_struct *task, u64 clone_flags)
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{
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struct __tasks_kfunc_map_value *v;
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v = insert_lookup_task(task);
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if (!v)
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return 0;
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/* Can't invoke bpf_task_release() on an untrusted pointer. */
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bpf_task_release(v->task);
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return 0;
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}
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SEC("tp_btf/task_newtask")
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__failure __msg("arg#0 pointer type STRUCT task_struct must point")
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int BPF_PROG(task_kfunc_release_fp, struct task_struct *task, u64 clone_flags)
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{
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struct task_struct *acquired = (struct task_struct *)&clone_flags;
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/* Cannot release random frame pointer. */
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bpf_task_release(acquired);
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return 0;
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}
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SEC("tp_btf/task_newtask")
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__failure __msg("arg#0 is ptr_or_null_ expected ptr_ or socket")
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int BPF_PROG(task_kfunc_release_null, struct task_struct *task, u64 clone_flags)
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{
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struct __tasks_kfunc_map_value local, *v;
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long status;
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struct task_struct *acquired, *old;
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s32 pid;
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status = bpf_probe_read_kernel(&pid, sizeof(pid), &task->pid);
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if (status)
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return 0;
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local.task = NULL;
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status = bpf_map_update_elem(&__tasks_kfunc_map, &pid, &local, BPF_NOEXIST);
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if (status)
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return status;
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v = bpf_map_lookup_elem(&__tasks_kfunc_map, &pid);
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if (!v)
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return -ENOENT;
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acquired = bpf_task_acquire(task);
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old = bpf_kptr_xchg(&v->task, acquired);
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/* old cannot be passed to bpf_task_release() without a NULL check. */
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bpf_task_release(old);
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bpf_task_release(old);
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return 0;
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}
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SEC("tp_btf/task_newtask")
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__failure __msg("release kernel function bpf_task_release expects")
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int BPF_PROG(task_kfunc_release_unacquired, struct task_struct *task, u64 clone_flags)
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{
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/* Cannot release trusted task pointer which was not acquired. */
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bpf_task_release(task);
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return 0;
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}
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SEC("tp_btf/task_newtask")
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__failure __msg("arg#0 is ptr_or_null_ expected ptr_ or socket")
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int BPF_PROG(task_kfunc_from_pid_no_null_check, struct task_struct *task, u64 clone_flags)
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{
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struct task_struct *acquired;
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acquired = bpf_task_from_pid(task->pid);
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/* Releasing bpf_task_from_pid() lookup without a NULL check. */
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bpf_task_release(acquired);
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return 0;
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}
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SEC("lsm/task_free")
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__failure __msg("reg type unsupported for arg#0 function")
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int BPF_PROG(task_kfunc_from_lsm_task_free, struct task_struct *task)
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{
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struct task_struct *acquired;
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/* the argument of lsm task_free hook is untrusted. */
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acquired = bpf_task_acquire(task);
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bpf_task_release(acquired);
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return 0;
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}
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