linux/security/loadpin/loadpin.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Module and Firmware Pinning Security Module
 *
 * Copyright 2011-2016 Google Inc.
 *
 * Author: Kees Cook <[email protected]>
 */

#define pr_fmt(fmt) …

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/kernel_read_file.h>
#include <linux/lsm_hooks.h>
#include <linux/mount.h>
#include <linux/blkdev.h>
#include <linux/path.h>
#include <linux/sched.h>	/* current */
#include <linux/string_helpers.h>
#include <linux/dm-verity-loadpin.h>
#include <uapi/linux/loadpin.h>
#include <uapi/linux/lsm.h>

#define VERITY_DIGEST_FILE_HEADER …

static void report_load(const char *origin, struct file *file, char *operation)
{ … }

static int enforce = … IS_ENABLED(…);
static char *exclude_read_files[READING_MAX_ID];
static int ignore_read_file_id[READING_MAX_ID] __ro_after_init;
static struct super_block *pinned_root;
static DEFINE_SPINLOCK(pinned_root_spinlock);
#ifdef CONFIG_SECURITY_LOADPIN_VERITY
static bool deny_reading_verity_digests;
#endif

#ifdef CONFIG_SYSCTL
static struct ctl_table loadpin_sysctl_table[] = …;

static void set_sysctl(bool is_writable)
{ … }
#else
static inline void set_sysctl(bool is_writable) { }
#endif

static void report_writable(struct super_block *mnt_sb, bool writable)
{ … }

/*
 * This must be called after early kernel init, since then the rootdev
 * is available.
 */
static bool sb_is_writable(struct super_block *mnt_sb)
{ … }

static void loadpin_sb_free_security(struct super_block *mnt_sb)
{ … }

static int loadpin_check(struct file *file, enum kernel_read_file_id id)
{ … }

static int loadpin_read_file(struct file *file, enum kernel_read_file_id id,
			     bool contents)
{ … }

static int loadpin_load_data(enum kernel_load_data_id id, bool contents)
{ … }

static const struct lsm_id loadpin_lsmid = …;

static struct security_hook_list loadpin_hooks[] __ro_after_init = …;

static void __init parse_exclude(void)
{ … }

static int __init loadpin_init(void)
{ … }

DEFINE_LSM(loadpin) = …;

#ifdef CONFIG_SECURITY_LOADPIN_VERITY

enum loadpin_securityfs_interface_index { … };

static int read_trusted_verity_root_digests(unsigned int fd)
{ … }

/******************************** securityfs ********************************/

static long dm_verity_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{ … }

static const struct file_operations loadpin_dm_verity_ops = …;

/**
 * init_loadpin_securityfs - create the securityfs directory for LoadPin
 *
 * We can not put this method normally under the loadpin_init() code path since
 * the security subsystem gets initialized before the vfs caches.
 *
 * Returns 0 if the securityfs directory creation was successful.
 */
static int __init init_loadpin_securityfs(void)
{ … }

fs_initcall(init_loadpin_securityfs);

#endif /* CONFIG_SECURITY_LOADPIN_VERITY */

/* Should not be mutable after boot, so not listed in sysfs (perm == 0). */
module_param(enforce, int, 0);
MODULE_PARM_DESC(…) …;
module_param_array_named(…);
MODULE_PARM_DESC(…) …;