// SPDX-License-Identifier: GPL-2.0#include <linux/init.h>#include <linux/mm.h>#include <linux/security.h>#include <linux/sysctl.h> /* amount of vm to protect from userspace access by both DAC and the LSM*/unsigned long mmap_min_addr;/* amount of vm to protect from userspace using CAP_SYS_RAWIO (DAC) */unsigned long dac_mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR;/* amount of vm to protect from userspace using the LSM = CONFIG_LSM_MMAP_MIN_ADDR */ /* * Update mmap_min_addr = max(dac_mmap_min_addr, CONFIG_LSM_MMAP_MIN_ADDR) */static void update_mmap_min_addr(void){#ifdef CONFIG_LSM_MMAP_MIN_ADDR	if (dac_mmap_min_addr > CONFIG_LSM_MMAP_MIN_ADDR)		mmap_min_addr = dac_mmap_min_addr;	else		mmap_min_addr = CONFIG_LSM_MMAP_MIN_ADDR;#else	mmap_min_addr = dac_mmap_min_addr;#endif} /* * sysctl handler which just sets dac_mmap_min_addr = the new value and then * calls update_mmap_min_addr() so non MAP_FIXED hints get rounded properly */int mmap_min_addr_handler(struct ctl_table *table, int write,			  void __user *buffer, size_t *lenp, loff_t *ppos){	int ret; 	if (write && !capable(CAP_SYS_RAWIO))		return -EPERM; 	ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos); 	update_mmap_min_addr(); 	return ret;} static int __init init_mmap_min_addr(void){	update_mmap_min_addr(); 	return 0;}pure_initcall(init_mmap_min_addr);