// SPDX-License-Identifier: GPL-2.0-only
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/ctype.h>
#include <linux/fd.h>
#include <linux/tty.h>
#include <linux/suspend.h>
#include <linux/root_dev.h>
#include <linux/security.h>
#include <linux/delay.h>
#include <linux/genhd.h>
#include <linux/mount.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/initrd.h>
#include <linux/async.h>
#include <linux/fs_struct.h>
#include <linux/slab.h>
#include <linux/ramfs.h>
#include <linux/shmem_fs.h>

#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
#include <linux/nfs_mount.h>
#include <linux/raid/detect.h>
#include <uapi/linux/mount.h>

#include "do_mounts.h"

int root_mountflags = MS_RDONLY | MS_SILENT;
static char * __initdata root_device_name;
static char __initdata saved_root_name[64];
static int root_wait;

dev_t ROOT_DEV;

static int __init load_ramdisk(char *str)
{
        pr_warn("ignoring the deprecated load_ramdisk= option\n");
        return 1;
}
__setup("load_ramdisk=", load_ramdisk);

static int __init readonly(char *str)
{
        if (*str)
                return 0;
        root_mountflags |= MS_RDONLY;
        return 1;
}

static int __init readwrite(char *str)
{
        if (*str)
                return 0;
        root_mountflags &= ~MS_RDONLY;
        return 1;
}

__setup("ro", readonly);
__setup("rw", readwrite);

#ifdef CONFIG_BLOCK
struct uuidcmp {
        const char *uuid;
        int len;
};

/**
 * match_dev_by_uuid - callback for finding a partition using its uuid
 * @dev:        device passed in by the caller
 * @data:       opaque pointer to the desired struct uuidcmp to match
 *
 * Returns 1 if the device matches, and 0 otherwise.
 */
static int match_dev_by_uuid(struct device *dev, const void *data)
{
        struct block_device *bdev = dev_to_bdev(dev);
        const struct uuidcmp *cmp = data;

        if (!bdev->bd_meta_info ||
            strncasecmp(cmp->uuid, bdev->bd_meta_info->uuid, cmp->len))
                return 0;
        return 1;
}

/**
 * devt_from_partuuid - looks up the dev_t of a partition by its UUID
 * @uuid_str:   char array containing ascii UUID
 *
 * The function will return the first partition which contains a matching
 * UUID value in its partition_meta_info struct.  This does not search
 * by filesystem UUIDs.
 *
 * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be
 * extracted and used as an offset from the partition identified by the UUID.
 *
 * Returns the matching dev_t on success or 0 on failure.
 */
static dev_t devt_from_partuuid(const char *uuid_str)
{
        struct uuidcmp cmp;
        struct device *dev = NULL;
        dev_t devt = 0;
        int offset = 0;
        char *slash;

        cmp.uuid = uuid_str;

        slash = strchr(uuid_str, '/');
        /* Check for optional partition number offset attributes. */
        if (slash) {
                char c = 0;

                /* Explicitly fail on poor PARTUUID syntax. */
                if (sscanf(slash + 1, "PARTNROFF=%d%c", &offset, &c) != 1)
                        goto clear_root_wait;
                cmp.len = slash - uuid_str;
        } else {
                cmp.len = strlen(uuid_str);
        }

        if (!cmp.len)
                goto clear_root_wait;

        dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);
        if (!dev)
                return 0;

        if (offset) {
                /*
                 * Attempt to find the requested partition by adding an offset
                 * to the partition number found by UUID.
                 */
                devt = part_devt(dev_to_disk(dev),
                                 dev_to_bdev(dev)->bd_partno + offset);
        } else {
                devt = dev->devt;
        }

        put_device(dev);
        return devt;

clear_root_wait:
        pr_err("VFS: PARTUUID= is invalid.\n"
               "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
        if (root_wait)
                pr_err("Disabling rootwait; root= is invalid.\n");
        root_wait = 0;
        return 0;
}

/**
 * match_dev_by_label - callback for finding a partition using its label
 * @dev:        device passed in by the caller
 * @data:       opaque pointer to the label to match
 *
 * Returns 1 if the device matches, and 0 otherwise.
 */
static int match_dev_by_label(struct device *dev, const void *data)
{
        struct block_device *bdev = dev_to_bdev(dev);
        const char *label = data;

        if (!bdev->bd_meta_info || strcmp(label, bdev->bd_meta_info->volname))
                return 0;
        return 1;
}

static dev_t devt_from_partlabel(const char *label)
{
        struct device *dev;
        dev_t devt = 0;

        dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);
        if (dev) {
                devt = dev->devt;
                put_device(dev);
        }

        return devt;
}

static dev_t devt_from_devname(const char *name)
{
        dev_t devt = 0;
        int part;
        char s[32];
        char *p;

        if (strlen(name) > 31)
                return 0;
        strcpy(s, name);
        for (p = s; *p; p++) {
                if (*p == '/')
                        *p = '!';
        }

        devt = blk_lookup_devt(s, 0);
        if (devt)
                return devt;

        /*
         * Try non-existent, but valid partition, which may only exist after
         * opening the device, like partitioned md devices.
         */
        while (p > s && isdigit(p[-1]))
                p--;
        if (p == s || !*p || *p == '0')
                return 0;

        /* try disk name without <part number> */
        part = simple_strtoul(p, NULL, 10);
        *p = '\0';
        devt = blk_lookup_devt(s, part);
        if (devt)
                return devt;

        /* try disk name without p<part number> */
        if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
                return 0;
        p[-1] = '\0';
        return blk_lookup_devt(s, part);
}
#endif /* CONFIG_BLOCK */

static dev_t devt_from_devnum(const char *name)
{
        unsigned maj, min, offset;
        dev_t devt = 0;
        char *p, dummy;

        if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 ||
            sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3) {
                devt = MKDEV(maj, min);
                if (maj != MAJOR(devt) || min != MINOR(devt))
                        return 0;
        } else {
                devt = new_decode_dev(simple_strtoul(name, &p, 16));
                if (*p)
                        return 0;
        }

        return devt;
}

/*
 *      Convert a name into device number.  We accept the following variants:
 *
 *      1) <hex_major><hex_minor> device number in hexadecimal represents itself
 *         no leading 0x, for example b302.
 *      2) /dev/nfs represents Root_NFS (0xff)
 *      3) /dev/<disk_name> represents the device number of disk
 *      4) /dev/<disk_name><decimal> represents the device number
 *         of partition - device number of disk plus the partition number
 *      5) /dev/<disk_name>p<decimal> - same as the above, that form is
 *         used when disk name of partitioned disk ends on a digit.
 *      6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
 *         unique id of a partition if the partition table provides it.
 *         The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
 *         partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
 *         filled hex representation of the 32-bit "NT disk signature", and PP
 *         is a zero-filled hex representation of the 1-based partition number.
 *      7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
 *         a partition with a known unique id.
 *      8) <major>:<minor> major and minor number of the device separated by
 *         a colon.
 *      9) PARTLABEL=<name> with name being the GPT partition label.
 *         MSDOS partitions do not support labels!
 *      10) /dev/cifs represents Root_CIFS (0xfe)
 *
 *      If name doesn't have fall into the categories above, we return (0,0).
 *      block_class is used to check if something is a disk name. If the disk
 *      name contains slashes, the device name has them replaced with
 *      bangs.
 */
dev_t name_to_dev_t(const char *name)
{
        if (strcmp(name, "/dev/nfs") == 0)
                return Root_NFS;
        if (strcmp(name, "/dev/cifs") == 0)
                return Root_CIFS;
        if (strcmp(name, "/dev/ram") == 0)
                return Root_RAM0;
#ifdef CONFIG_BLOCK
        if (strncmp(name, "PARTUUID=", 9) == 0)
                return devt_from_partuuid(name + 9);
        if (strncmp(name, "PARTLABEL=", 10) == 0)
                return devt_from_partlabel(name + 10);
        if (strncmp(name, "/dev/", 5) == 0)
                return devt_from_devname(name + 5);
#endif
        return devt_from_devnum(name);
}
EXPORT_SYMBOL_GPL(name_to_dev_t);

static int __init root_dev_setup(char *line)
{
        strlcpy(saved_root_name, line, sizeof(saved_root_name));
        return 1;
}

__setup("root=", root_dev_setup);

static int __init rootwait_setup(char *str)
{
        if (*str)
                return 0;
        root_wait = 1;
        return 1;
}

__setup("rootwait", rootwait_setup);

static char * __initdata root_mount_data;
static int __init root_data_setup(char *str)
{
        root_mount_data = str;
        return 1;
}

static char * __initdata root_fs_names;
static int __init fs_names_setup(char *str)
{
        root_fs_names = str;
        return 1;
}

static unsigned int __initdata root_delay;
static int __init root_delay_setup(char *str)
{
        root_delay = simple_strtoul(str, NULL, 0);
        return 1;
}

__setup("rootflags=", root_data_setup);
__setup("rootfstype=", fs_names_setup);
__setup("rootdelay=", root_delay_setup);

static void __init get_fs_names(char *page)
{
        char *s = page;

        if (root_fs_names) {
                strcpy(page, root_fs_names);
                while (*s++) {
                        if (s[-1] == ',')
                                s[-1] = '\0';
                }
        } else {
                int len = get_filesystem_list(page);
                char *p, *next;

                page[len] = '\0';
                for (p = page-1; p; p = next) {
                        next = strchr(++p, '\n');
                        if (*p++ != '\t')
                                continue;
                        while ((*s++ = *p++) != '\n')
                                ;
                        s[-1] = '\0';
                }
        }
        *s = '\0';
}

static int __init do_mount_root(const char *name, const char *fs,
                                 const int flags, const void *data)
{
        struct super_block *s;
        struct page *p = NULL;
        char *data_page = NULL;
        int ret;

        if (data) {
                /* init_mount() requires a full page as fifth argument */
                p = alloc_page(GFP_KERNEL);
                if (!p)
                        return -ENOMEM;
                data_page = page_address(p);
                /* zero-pad. init_mount() will make sure it's terminated */
                strncpy(data_page, data, PAGE_SIZE);
        }

        ret = init_mount(name, "/root", fs, flags, data_page);
        if (ret)
                goto out;

        init_chdir("/root");
        s = current->fs->pwd.dentry->d_sb;
        ROOT_DEV = s->s_dev;
        printk(KERN_INFO
               "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
               s->s_type->name,
               sb_rdonly(s) ? " readonly" : "",
               MAJOR(ROOT_DEV), MINOR(ROOT_DEV));

out:
        if (p)
                put_page(p);
        return ret;
}

void __init mount_block_root(char *name, int flags)
{
        struct page *page = alloc_page(GFP_KERNEL);
        char *fs_names = page_address(page);
        char *p;
        char b[BDEVNAME_SIZE];

        scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)",
                  MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
        get_fs_names(fs_names);
retry:
        for (p = fs_names; *p; p += strlen(p)+1) {
                int err = do_mount_root(name, p, flags, root_mount_data);
                switch (err) {
                        case 0:
                                goto out;
                        case -EACCES:
                        case -EINVAL:
                                continue;
                }
                /*
                 * Allow the user to distinguish between failed sys_open
                 * and bad superblock on root device.
                 * and give them a list of the available devices
                 */
                printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
                                root_device_name, b, err);
                printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");

                printk_all_partitions();
#ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
                printk("DEBUG_BLOCK_EXT_DEVT is enabled, you need to specify "
                       "explicit textual name for \"root=\" boot option.\n");
#endif
                panic("VFS: Unable to mount root fs on %s", b);
        }
        if (!(flags & SB_RDONLY)) {
                flags |= SB_RDONLY;
                goto retry;
        }

        printk("List of all partitions:\n");
        printk_all_partitions();
        printk("No filesystem could mount root, tried: ");
        for (p = fs_names; *p; p += strlen(p)+1)
                printk(" %s", p);
        printk("\n");
        panic("VFS: Unable to mount root fs on %s", b);
out:
        put_page(page);
}
 
#ifdef CONFIG_ROOT_NFS

#define NFSROOT_TIMEOUT_MIN     5
#define NFSROOT_TIMEOUT_MAX     30
#define NFSROOT_RETRY_MAX       5

static int __init mount_nfs_root(void)
{
        char *root_dev, *root_data;
        unsigned int timeout;
        int try, err;

        err = nfs_root_data(&root_dev, &root_data);
        if (err != 0)
                return 0;

        /*
         * The server or network may not be ready, so try several
         * times.  Stop after a few tries in case the client wants
         * to fall back to other boot methods.
         */
        timeout = NFSROOT_TIMEOUT_MIN;
        for (try = 1; ; try++) {
                err = do_mount_root(root_dev, "nfs",
                                        root_mountflags, root_data);
                if (err == 0)
                        return 1;
                if (try > NFSROOT_RETRY_MAX)
                        break;

                /* Wait, in case the server refused us immediately */
                ssleep(timeout);
                timeout <<= 1;
                if (timeout > NFSROOT_TIMEOUT_MAX)
                        timeout = NFSROOT_TIMEOUT_MAX;
        }
        return 0;
}
#endif

#ifdef CONFIG_CIFS_ROOT

extern int cifs_root_data(char **dev, char **opts);

#define CIFSROOT_TIMEOUT_MIN    5
#define CIFSROOT_TIMEOUT_MAX    30
#define CIFSROOT_RETRY_MAX      5

static int __init mount_cifs_root(void)
{
        char *root_dev, *root_data;
        unsigned int timeout;
        int try, err;

        err = cifs_root_data(&root_dev, &root_data);
        if (err != 0)
                return 0;

        timeout = CIFSROOT_TIMEOUT_MIN;
        for (try = 1; ; try++) {
                err = do_mount_root(root_dev, "cifs", root_mountflags,
                                    root_data);
                if (err == 0)
                        return 1;
                if (try > CIFSROOT_RETRY_MAX)
                        break;

                ssleep(timeout);
                timeout <<= 1;
                if (timeout > CIFSROOT_TIMEOUT_MAX)
                        timeout = CIFSROOT_TIMEOUT_MAX;
        }
        return 0;
}
#endif

void __init mount_root(void)
{
#ifdef CONFIG_ROOT_NFS
        if (ROOT_DEV == Root_NFS) {
                if (!mount_nfs_root())
                        printk(KERN_ERR "VFS: Unable to mount root fs via NFS.\n");
                return;
        }
#endif
#ifdef CONFIG_CIFS_ROOT
        if (ROOT_DEV == Root_CIFS) {
                if (!mount_cifs_root())
                        printk(KERN_ERR "VFS: Unable to mount root fs via SMB.\n");
                return;
        }
#endif
#ifdef CONFIG_BLOCK
        {
                int err = create_dev("/dev/root", ROOT_DEV);

                if (err < 0)
                        pr_emerg("Failed to create /dev/root: %d\n", err);
                mount_block_root("/dev/root", root_mountflags);
        }
#endif
}

/*
 * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
 */
void __init prepare_namespace(void)
{
        if (root_delay) {
                printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
                       root_delay);
                ssleep(root_delay);
        }

        /*
         * wait for the known devices to complete their probing
         *
         * Note: this is a potential source of long boot delays.
         * For example, it is not atypical to wait 5 seconds here
         * for the touchpad of a laptop to initialize.
         */
        wait_for_device_probe();

        md_run_setup();

        if (saved_root_name[0]) {
                root_device_name = saved_root_name;
                if (!strncmp(root_device_name, "mtd", 3) ||
                    !strncmp(root_device_name, "ubi", 3)) {
                        mount_block_root(root_device_name, root_mountflags);
                        goto out;
                }
                ROOT_DEV = name_to_dev_t(root_device_name);
                if (strncmp(root_device_name, "/dev/", 5) == 0)
                        root_device_name += 5;
        }

        if (initrd_load())
                goto out;

        /* wait for any asynchronous scanning to complete */
        if ((ROOT_DEV == 0) && root_wait) {
                printk(KERN_INFO "Waiting for root device %s...\n",
                        saved_root_name);
                while (driver_probe_done() != 0 ||
                        (ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
                        msleep(5);
                async_synchronize_full();
        }

        mount_root();
out:
        devtmpfs_mount();
        init_mount(".", "/", NULL, MS_MOVE, NULL);
        init_chroot(".");
}

static bool is_tmpfs;
static int rootfs_init_fs_context(struct fs_context *fc)
{
        if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
                return shmem_init_fs_context(fc);

        return ramfs_init_fs_context(fc);
}

struct file_system_type rootfs_fs_type = {
        .name           = "rootfs",
        .init_fs_context = rootfs_init_fs_context,
        .kill_sb        = kill_litter_super,
};

void __init init_rootfs(void)
{
        if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
                (!root_fs_names || strstr(root_fs_names, "tmpfs")))
                is_tmpfs = true;
}