// SPDX-License-Identifier: GPL-2.0

/*
 * dm-init.c
 * Copyright (C) 2017 The Chromium OS Authors <chromium-os-dev@chromium.org>
 *
 * This file is released under the GPLv2.
 */

#include <linux/ctype.h>
#include <linux/device.h>
#include <linux/device-mapper.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/moduleparam.h>

#define DM_MSG_PREFIX "init"
#define DM_MAX_DEVICES 256
#define DM_MAX_TARGETS 256
#define DM_MAX_STR_SIZE 4096

static char *create;

/*
 * Format: dm-mod.create=<name>,<uuid>,<minor>,<flags>,<table>[,<table>+][;<name>,<uuid>,<minor>,<flags>,<table>[,<table>+]+]
 * Table format: <start_sector> <num_sectors> <target_type> <target_args>
 *
 * See Documentation/admin-guide/device-mapper/dm-init.rst for dm-mod.create="..." format
 * details.
 */

struct dm_device {
        struct dm_ioctl dmi;
        struct dm_target_spec *table[DM_MAX_TARGETS];
        char *target_args_array[DM_MAX_TARGETS];
        struct list_head list;
};

static const char * const dm_allowed_targets[] __initconst = {
        "crypt",
        "delay",
        "linear",
        "snapshot-origin",
        "striped",
        "verity",
};

static int __init dm_verify_target_type(const char *target)
{
        unsigned int i;

        for (i = 0; i < ARRAY_SIZE(dm_allowed_targets); i++) {
                if (!strcmp(dm_allowed_targets[i], target))
                        return 0;
        }
        return -EINVAL;
}

static void __init dm_setup_cleanup(struct list_head *devices)
{
        struct dm_device *dev, *tmp;
        unsigned int i;

        list_for_each_entry_safe(dev, tmp, devices, list) {
                list_del(&dev->list);
                for (i = 0; i < dev->dmi.target_count; i++) {
                        kfree(dev->table[i]);
                        kfree(dev->target_args_array[i]);
                }
                kfree(dev);
        }
}

/**
 * str_field_delimit - delimit a string based on a separator char.
 * @str: the pointer to the string to delimit.
 * @separator: char that delimits the field
 *
 * Find a @separator and replace it by '\0'.
 * Remove leading and trailing spaces.
 * Return the remainder string after the @separator.
 */
static char __init *str_field_delimit(char **str, char separator)
{
        char *s;

        /* TODO: add support for escaped characters */
        *str = skip_spaces(*str);
        s = strchr(*str, separator);
        /* Delimit the field and remove trailing spaces */
        if (s)
                *s = '\0';
        *str = strim(*str);
        return s ? ++s : NULL;
}

/**
 * dm_parse_table_entry - parse a table entry
 * @dev: device to store the parsed information.
 * @str: the pointer to a string with the format:
 *      <start_sector> <num_sectors> <target_type> <target_args>[, ...]
 *
 * Return the remainder string after the table entry, i.e, after the comma which
 * delimits the entry or NULL if reached the end of the string.
 */
static char __init *dm_parse_table_entry(struct dm_device *dev, char *str)
{
        const unsigned int n = dev->dmi.target_count - 1;
        struct dm_target_spec *sp;
        unsigned int i;
        /* fields:  */
        char *field[4];
        char *next;

        field[0] = str;
        /* Delimit first 3 fields that are separated by space */
        for (i = 0; i < ARRAY_SIZE(field) - 1; i++) {
                field[i + 1] = str_field_delimit(&field[i], ' ');
                if (!field[i + 1])
                        return ERR_PTR(-EINVAL);
        }
        /* Delimit last field that can be terminated by comma */
        next = str_field_delimit(&field[i], ',');

        sp = kzalloc(sizeof(*sp), GFP_KERNEL);
        if (!sp)
                return ERR_PTR(-ENOMEM);
        dev->table[n] = sp;

        /* start_sector */
        if (kstrtoull(field[0], 0, &sp->sector_start))
                return ERR_PTR(-EINVAL);
        /* num_sector */
        if (kstrtoull(field[1], 0, &sp->length))
                return ERR_PTR(-EINVAL);
        /* target_type */
        strscpy(sp->target_type, field[2], sizeof(sp->target_type));
        if (dm_verify_target_type(sp->target_type)) {
                DMERR("invalid type \"%s\"", sp->target_type);
                return ERR_PTR(-EINVAL);
        }
        /* target_args */
        dev->target_args_array[n] = kstrndup(field[3], DM_MAX_STR_SIZE,
                                             GFP_KERNEL);
        if (!dev->target_args_array[n])
                return ERR_PTR(-ENOMEM);

        return next;
}

/**
 * dm_parse_table - parse "dm-mod.create=" table field
 * @dev: device to store the parsed information.
 * @str: the pointer to a string with the format:
 *      <table>[,<table>+]
 */
static int __init dm_parse_table(struct dm_device *dev, char *str)
{
        char *table_entry = str;

        while (table_entry) {
                DMDEBUG("parsing table \"%s\"", str);
                if (++dev->dmi.target_count > DM_MAX_TARGETS) {
                        DMERR("too many targets %u > %d",
                              dev->dmi.target_count, DM_MAX_TARGETS);
                        return -EINVAL;
                }
                table_entry = dm_parse_table_entry(dev, table_entry);
                if (IS_ERR(table_entry)) {
                        DMERR("couldn't parse table");
                        return PTR_ERR(table_entry);
                }
        }

        return 0;
}

/**
 * dm_parse_device_entry - parse a device entry
 * @dev: device to store the parsed information.
 * @str: the pointer to a string with the format:
 *      name,uuid,minor,flags,table[; ...]
 *
 * Return the remainder string after the table entry, i.e, after the semi-colon
 * which delimits the entry or NULL if reached the end of the string.
 */
static char __init *dm_parse_device_entry(struct dm_device *dev, char *str)
{
        /* There are 5 fields: name,uuid,minor,flags,table; */
        char *field[5];
        unsigned int i;
        char *next;

        field[0] = str;
        /* Delimit first 4 fields that are separated by comma */
        for (i = 0; i < ARRAY_SIZE(field) - 1; i++) {
                field[i+1] = str_field_delimit(&field[i], ',');
                if (!field[i+1])
                        return ERR_PTR(-EINVAL);
        }
        /* Delimit last field that can be delimited by semi-colon */
        next = str_field_delimit(&field[i], ';');

        /* name */
        strscpy(dev->dmi.name, field[0], sizeof(dev->dmi.name));
        /* uuid */
        strscpy(dev->dmi.uuid, field[1], sizeof(dev->dmi.uuid));
        /* minor */
        if (strlen(field[2])) {
                if (kstrtoull(field[2], 0, &dev->dmi.dev))
                        return ERR_PTR(-EINVAL);
                dev->dmi.flags |= DM_PERSISTENT_DEV_FLAG;
        }
        /* flags */
        if (!strcmp(field[3], "ro"))
                dev->dmi.flags |= DM_READONLY_FLAG;
        else if (strcmp(field[3], "rw"))
                return ERR_PTR(-EINVAL);
        /* table */
        if (dm_parse_table(dev, field[4]))
                return ERR_PTR(-EINVAL);

        return next;
}

/**
 * dm_parse_devices - parse "dm-mod.create=" argument
 * @devices: list of struct dm_device to store the parsed information.
 * @str: the pointer to a string with the format:
 *      <device>[;<device>+]
 */
static int __init dm_parse_devices(struct list_head *devices, char *str)
{
        unsigned long ndev = 0;
        struct dm_device *dev;
        char *device = str;

        DMDEBUG("parsing \"%s\"", str);
        while (device) {
                dev = kzalloc(sizeof(*dev), GFP_KERNEL);
                if (!dev)
                        return -ENOMEM;
                list_add_tail(&dev->list, devices);

                if (++ndev > DM_MAX_DEVICES) {
                        DMERR("too many devices %lu > %d",
                              ndev, DM_MAX_DEVICES);
                        return -EINVAL;
                }

                device = dm_parse_device_entry(dev, device);
                if (IS_ERR(device)) {
                        DMERR("couldn't parse device");
                        return PTR_ERR(device);
                }
        }

        return 0;
}

/**
 * dm_init_init - parse "dm-mod.create=" argument and configure drivers
 */
static int __init dm_init_init(void)
{
        struct dm_device *dev;
        LIST_HEAD(devices);
        char *str;
        int r;

        if (!create)
                return 0;

        if (strlen(create) >= DM_MAX_STR_SIZE) {
                DMERR("Argument is too big. Limit is %d", DM_MAX_STR_SIZE);
                return -EINVAL;
        }
        str = kstrndup(create, DM_MAX_STR_SIZE, GFP_KERNEL);
        if (!str)
                return -ENOMEM;

        r = dm_parse_devices(&devices, str);
        if (r)
                goto out;

        DMINFO("waiting for all devices to be available before creating mapped devices");
        wait_for_device_probe();

        list_for_each_entry(dev, &devices, list) {
                if (dm_early_create(&dev->dmi, dev->table,
                                    dev->target_args_array))
                        break;
        }
out:
        kfree(str);
        dm_setup_cleanup(&devices);
        return r;
}

late_initcall(dm_init_init);

module_param(create, charp, 0);
MODULE_PARM_DESC(create, "Create a mapped device in early boot");