// SPDX-License-Identifier: GPL-2.0/* Lock down the kernel * * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public Licence * as published by the Free Software Foundation; either version * 2 of the Licence, or (at your option) any later version. */ #include <linux/security.h>#include <linux/export.h>#include <linux/lsm_hooks.h>#include <uapi/linux/lsm.h> static enum lockdown_reason kernel_locked_down; static const enum lockdown_reason lockdown_levels[] = {LOCKDOWN_NONE,						 LOCKDOWN_INTEGRITY_MAX,						 LOCKDOWN_CONFIDENTIALITY_MAX}; /* * Put the kernel into lock-down mode. */static int lock_kernel_down(const char *where, enum lockdown_reason level){	if (kernel_locked_down >= level)		return -EPERM; 	kernel_locked_down = level;	pr_notice("Kernel is locked down from %s; see man kernel_lockdown.7\n",		  where);	return 0;} static int __init lockdown_param(char *level){	if (!level)		return -EINVAL; 	if (strcmp(level, "integrity") == 0)		lock_kernel_down("command line", LOCKDOWN_INTEGRITY_MAX);	else if (strcmp(level, "confidentiality") == 0)		lock_kernel_down("command line", LOCKDOWN_CONFIDENTIALITY_MAX);	else		return -EINVAL; 	return 0;} early_param("lockdown", lockdown_param); /** * lockdown_is_locked_down - Find out if the kernel is locked down * @what: Tag to use in notice generated if lockdown is in effect */static int lockdown_is_locked_down(enum lockdown_reason what){	if (WARN(what >= LOCKDOWN_CONFIDENTIALITY_MAX,		 "Invalid lockdown reason"))		return -EPERM; 	if (kernel_locked_down >= what) {		if (lockdown_reasons[what])			pr_notice_ratelimited("Lockdown: %s: %s is restricted; see man kernel_lockdown.7\n",				  current->comm, lockdown_reasons[what]);		return -EPERM;	} 	return 0;} static struct security_hook_list lockdown_hooks[] __ro_after_init = {	LSM_HOOK_INIT(locked_down, lockdown_is_locked_down),}; static const struct lsm_id lockdown_lsmid = {	.name = "lockdown",	.id = LSM_ID_LOCKDOWN,}; static int __init lockdown_lsm_init(void){#if defined(CONFIG_LOCK_DOWN_KERNEL_FORCE_INTEGRITY)	lock_kernel_down("Kernel configuration", LOCKDOWN_INTEGRITY_MAX);#elif defined(CONFIG_LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY)	lock_kernel_down("Kernel configuration", LOCKDOWN_CONFIDENTIALITY_MAX);#endif	security_add_hooks(lockdown_hooks, ARRAY_SIZE(lockdown_hooks),			   &lockdown_lsmid);	return 0;} static ssize_t lockdown_read(struct file *filp, char __user *buf, size_t count,			     loff_t *ppos){	char temp[80] = "";	int i, offset = 0; 	for (i = 0; i < ARRAY_SIZE(lockdown_levels); i++) {		enum lockdown_reason level = lockdown_levels[i]; 		if (lockdown_reasons[level]) {			const char *label = lockdown_reasons[level]; 			if (kernel_locked_down == level)				offset += sprintf(temp+offset, "[%s] ", label);			else				offset += sprintf(temp+offset, "%s ", label);		}	} 	/* Convert the last space to a newline if needed. */	if (offset > 0)		temp[offset-1] = '\n'; 	return simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));} static ssize_t lockdown_write(struct file *file, const char __user *buf,			      size_t n, loff_t *ppos){	char *state;	int i, len, err = -EINVAL; 	state = memdup_user_nul(buf, n);	if (IS_ERR(state))		return PTR_ERR(state); 	len = strlen(state);	if (len && state[len-1] == '\n') {		state[len-1] = '\0';		len--;	} 	for (i = 0; i < ARRAY_SIZE(lockdown_levels); i++) {		enum lockdown_reason level = lockdown_levels[i];		const char *label = lockdown_reasons[level]; 		if (label && !strcmp(state, label))			err = lock_kernel_down("securityfs", level);	} 	kfree(state);	return err ? err : n;} static const struct file_operations lockdown_ops = {	.read  = lockdown_read,	.write = lockdown_write,}; static int __init lockdown_secfs_init(void){	struct dentry *dentry; 	dentry = securityfs_create_file("lockdown", 0644, NULL, NULL,					&lockdown_ops);	return PTR_ERR_OR_ZERO(dentry);} #ifdef CONFIG_SECURITY_LOCKDOWN_LSM_EARLYDEFINE_EARLY_LSM(lockdown) = {#elseDEFINE_LSM(lockdown) = {#endif	.id = &lockdown_lsmid,	.init = lockdown_lsm_init,	.initcall_core = lockdown_secfs_init,};