proc_sysctl.c

// SPDX-License-Identifier: GPL-2.0
/*
 * /proc/sys support
 */
#include <linux/init.h>
#include <linux/sysctl.h>
#include <linux/poll.h>
#include <linux/proc_fs.h>
#include <linux/printk.h>
#include <linux/security.h>
#include <linux/sched.h>
#include <linux/cred.h>
#include <linux/namei.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/bpf-cgroup.h>
#include "internal.h"

static const struct dentry_operations proc_sys_dentry_operations;
static const struct file_operations proc_sys_file_operations;
static const struct inode_operations proc_sys_inode_operations;
static const struct file_operations proc_sys_dir_file_operations;
static const struct inode_operations proc_sys_dir_operations;

/* shared constants to be used in various sysctls */
const int sysctl_vals[] = { 0, 1, INT_MAX };
EXPORT_SYMBOL(sysctl_vals);

/* Support for permanently empty directories */

struct ctl_table sysctl_mount_point[] = {
	{ }
};

static bool is_empty_dir(struct ctl_table_header *head)
{
	return head->ctl_table[0].child == sysctl_mount_point;
}

static void set_empty_dir(struct ctl_dir *dir)
{
	dir->header.ctl_table[0].child = sysctl_mount_point;
}

static void clear_empty_dir(struct ctl_dir *dir)

{
	dir->header.ctl_table[0].child = NULL;
}

void proc_sys_poll_notify(struct ctl_table_poll *poll)
{
	if (!poll)
		return;

	atomic_inc(&poll->event);
	wake_up_interruptible(&poll->wait);
}

static struct ctl_table root_table[] = {
	{
		.procname = "",
		.mode = S_IFDIR|S_IRUGO|S_IXUGO,
	},
	{ }
};
static struct ctl_table_root sysctl_table_root = {
	.default_set.dir.header = {
		{{.count = 1,
		  .nreg = 1,