// SPDX-License-Identifier: GPL-2.0-only
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/* Copyright (c) 2020 Facebook */
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#include <linux/init.h>
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#include <linux/namei.h>
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#include <linux/pid_namespace.h>
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#include <linux/fs.h>
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#include <linux/fdtable.h>
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#include <linux/filter.h>
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#include <linux/btf_ids.h>
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struct bpf_iter_seq_task_common {
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struct pid_namespace *ns;
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};
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struct bpf_iter_seq_task_info {
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/* The first field must be struct bpf_iter_seq_task_common.
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* this is assumed by {init, fini}_seq_pidns() callback functions.
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*/
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struct bpf_iter_seq_task_common common;
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u32 tid;
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};
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static struct task_struct *task_seq_get_next(struct pid_namespace *ns,
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u32 *tid,
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bool skip_if_dup_files)
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{
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struct task_struct *task = NULL;
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struct pid *pid;
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rcu_read_lock();
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retry:
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pid = find_ge_pid(*tid, ns);
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if (pid) {
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*tid = pid_nr_ns(pid, ns);
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task = get_pid_task(pid, PIDTYPE_PID);
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if (!task) {
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++*tid;
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goto retry;
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} else if (skip_if_dup_files && task->tgid != task->pid &&
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task->files == task->group_leader->files) {
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put_task_struct(task);
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task = NULL;
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++*tid;
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goto retry;
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}
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}
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rcu_read_unlock();
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return task;
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}
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static void *task_seq_start(struct seq_file *seq, loff_t *pos)
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{
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struct bpf_iter_seq_task_info *info = seq->private;
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struct task_struct *task;
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task = task_seq_get_next(info->common.ns, &info->tid, false);
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if (!task)
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return NULL;
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if (*pos == 0)
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++*pos;
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return task;
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}
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static void *task_seq_next(struct seq_file *seq, void *v, loff_t *pos)
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{
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struct bpf_iter_seq_task_info *info = seq->private;
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struct task_struct *task;
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++*pos;
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++info->tid;
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put_task_struct((struct task_struct *)v);
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task = task_seq_get_next(info->common.ns, &info->tid, false);
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if (!task)
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return NULL;
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return task;
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}
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struct bpf_iter__task {
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__bpf_md_ptr(struct bpf_iter_meta *, meta);
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__bpf_md_ptr(struct task_struct *, task);
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};
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DEFINE_BPF_ITER_FUNC(task, struct bpf_iter_meta *meta, struct task_struct *task)
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static int __task_seq_show(struct seq_file *seq, struct task_struct *task,
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bool in_stop)
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{
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struct bpf_iter_meta meta;
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struct bpf_iter__task ctx;
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struct bpf_prog *prog;
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meta.seq = seq;
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prog = bpf_iter_get_info(&meta, in_stop);
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if (!prog)
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return 0;
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meta.seq = seq;
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ctx.meta = &meta;
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ctx.task = task;
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return bpf_iter_run_prog(prog, &ctx);
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}
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static int task_seq_show(struct seq_file *seq, void *v)
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{
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return __task_seq_show(seq, v, false);
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}
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static void task_seq_stop(struct seq_file *seq, void *v)
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{
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if (!v)
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(void)__task_seq_show(seq, v, true);
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else
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put_task_struct((struct task_struct *)v);
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}
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static const struct seq_operations task_seq_ops = {
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.start = task_seq_start,
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.next = task_seq_next,
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.stop = task_seq_stop,
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.show = task_seq_show,
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};
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struct bpf_iter_seq_task_file_info {
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/* The first field must be struct bpf_iter_seq_task_common.
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* this is assumed by {init, fini}_seq_pidns() callback functions.
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*/
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struct bpf_iter_seq_task_common common;
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struct task_struct *task;
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struct files_struct *files;
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u32 tid;
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u32 fd;
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};
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static struct file *
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task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info)
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{
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struct pid_namespace *ns = info->common.ns;
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u32 curr_tid = info->tid, max_fds;
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struct files_struct *curr_files;
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struct task_struct *curr_task;
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int curr_fd = info->fd;
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/* If this function returns a non-NULL file object,
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* it held a reference to the task/files_struct/file.
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* Otherwise, it does not hold any reference.
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*/
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again:
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if (info->task) {
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curr_task = info->task;
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curr_files = info->files;
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curr_fd = info->fd;
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} else {
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curr_task = task_seq_get_next(ns, &curr_tid, true);
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if (!curr_task) {
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info->task = NULL;
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info->files = NULL;
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info->tid = curr_tid;
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return NULL;
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}
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curr_files = get_files_struct(curr_task);
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if (!curr_files) {
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put_task_struct(curr_task);
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curr_tid = curr_tid + 1;
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info->fd = 0;
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goto again;
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}
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info->files = curr_files;
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info->task = curr_task;
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if (curr_tid == info->tid) {
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curr_fd = info->fd;
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} else {
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info->tid = curr_tid;
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curr_fd = 0;
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}
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}
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rcu_read_lock();
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max_fds = files_fdtable(curr_files)->max_fds;
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for (; curr_fd < max_fds; curr_fd++) {
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struct file *f;
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f = fcheck_files(curr_files, curr_fd);
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if (!f)
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continue;
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if (!get_file_rcu(f))
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continue;
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/* set info->fd */
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info->fd = curr_fd;
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rcu_read_unlock();
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return f;
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}
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/* the current task is done, go to the next task */
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rcu_read_unlock();
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put_files_struct(curr_files);
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put_task_struct(curr_task);
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info->task = NULL;
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info->files = NULL;
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info->fd = 0;
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curr_tid = ++(info->tid);
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goto again;
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}
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static void *task_file_seq_start(struct seq_file *seq, loff_t *pos)
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{
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struct bpf_iter_seq_task_file_info *info = seq->private;
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struct file *file;
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info->task = NULL;
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info->files = NULL;
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file = task_file_seq_get_next(info);
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if (file && *pos == 0)
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++*pos;
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return file;
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}
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static void *task_file_seq_next(struct seq_file *seq, void *v, loff_t *pos)
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{
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struct bpf_iter_seq_task_file_info *info = seq->private;
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++*pos;
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++info->fd;
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fput((struct file *)v);
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return task_file_seq_get_next(info);
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}
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struct bpf_iter__task_file {
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__bpf_md_ptr(struct bpf_iter_meta *, meta);
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__bpf_md_ptr(struct task_struct *, task);
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u32 fd __aligned(8);
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__bpf_md_ptr(struct file *, file);
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};
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DEFINE_BPF_ITER_FUNC(task_file, struct bpf_iter_meta *meta,
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struct task_struct *task, u32 fd,
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struct file *file)
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static int __task_file_seq_show(struct seq_file *seq, struct file *file,
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bool in_stop)
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{
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struct bpf_iter_seq_task_file_info *info = seq->private;
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struct bpf_iter__task_file ctx;
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struct bpf_iter_meta meta;
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struct bpf_prog *prog;
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meta.seq = seq;
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prog = bpf_iter_get_info(&meta, in_stop);
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if (!prog)
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return 0;
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ctx.meta = &meta;
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ctx.task = info->task;
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ctx.fd = info->fd;
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ctx.file = file;
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return bpf_iter_run_prog(prog, &ctx);
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}
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static int task_file_seq_show(struct seq_file *seq, void *v)
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{
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return __task_file_seq_show(seq, v, false);
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}
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static void task_file_seq_stop(struct seq_file *seq, void *v)
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{
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struct bpf_iter_seq_task_file_info *info = seq->private;
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if (!v) {
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(void)__task_file_seq_show(seq, v, true);
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} else {
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fput((struct file *)v);
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put_files_struct(info->files);
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put_task_struct(info->task);
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info->files = NULL;
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info->task = NULL;
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}
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}
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static int init_seq_pidns(void *priv_data, struct bpf_iter_aux_info *aux)
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{
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struct bpf_iter_seq_task_common *common = priv_data;
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common->ns = get_pid_ns(task_active_pid_ns(current));
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return 0;
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}
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static void fini_seq_pidns(void *priv_data)
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{
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struct bpf_iter_seq_task_common *common = priv_data;
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put_pid_ns(common->ns);
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}
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static const struct seq_operations task_file_seq_ops = {
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.start = task_file_seq_start,
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.next = task_file_seq_next,
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.stop = task_file_seq_stop,
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.show = task_file_seq_show,
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};
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BTF_ID_LIST(btf_task_file_ids)
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BTF_ID(struct, task_struct)
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BTF_ID(struct, file)
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static const struct bpf_iter_seq_info task_seq_info = {
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.seq_ops = &task_seq_ops,
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.init_seq_private = init_seq_pidns,
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.fini_seq_private = fini_seq_pidns,
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.seq_priv_size = sizeof(struct bpf_iter_seq_task_info),
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};
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static struct bpf_iter_reg task_reg_info = {
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.target = "task",
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.ctx_arg_info_size = 1,
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.ctx_arg_info = {
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{ offsetof(struct bpf_iter__task, task),
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PTR_TO_BTF_ID_OR_NULL },
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},
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.seq_info = &task_seq_info,
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};
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static const struct bpf_iter_seq_info task_file_seq_info = {
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.seq_ops = &task_file_seq_ops,
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.init_seq_private = init_seq_pidns,
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.fini_seq_private = fini_seq_pidns,
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.seq_priv_size = sizeof(struct bpf_iter_seq_task_file_info),
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};
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static struct bpf_iter_reg task_file_reg_info = {
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.target = "task_file",
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.ctx_arg_info_size = 2,
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.ctx_arg_info = {
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{ offsetof(struct bpf_iter__task_file, task),
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PTR_TO_BTF_ID_OR_NULL },
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{ offsetof(struct bpf_iter__task_file, file),
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PTR_TO_BTF_ID_OR_NULL },
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},
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.seq_info = &task_file_seq_info,
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};
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static int __init task_iter_init(void)
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{
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int ret;
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task_reg_info.ctx_arg_info[0].btf_id = btf_task_file_ids[0];
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ret = bpf_iter_reg_target(&task_reg_info);
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if (ret)
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return ret;
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task_file_reg_info.ctx_arg_info[0].btf_id = btf_task_file_ids[0];
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task_file_reg_info.ctx_arg_info[1].btf_id = btf_task_file_ids[1];
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return bpf_iter_reg_target(&task_file_reg_info);
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}
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late_initcall(task_iter_init);
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