// SPDX-License-Identifier: GPL-2.0
#include <linux/init.h>
#include <linux/async.h>
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/delay.h>
#include <linux/string.h>
#include <linux/dirent.h>
#include <linux/syscalls.h>
#include <linux/utime.h>
#include <linux/file.h>
#include <linux/kstrtox.h>
#include <linux/memblock.h>
#include <linux/mm.h>
#include <linux/namei.h>
#include <linux/init_syscalls.h>
#include <linux/umh.h>
#include <linux/security.h>
#include <linux/overflow.h>

#include "do_mounts.h"
#include "initramfs_internal.h"

static __initdata bool csum_present;
static __initdata u32 io_csum;

static ssize_t __init xwrite(struct file *file, const unsigned char *p,
                size_t count, loff_t *pos)
{
        ssize_t out = 0;

        /* sys_write only can write MAX_RW_COUNT aka 2G-4K bytes at most */
        while (count) {
                ssize_t rv = kernel_write(file, p, count, pos);

                if (rv < 0) {
                        if (rv == -EINTR || rv == -EAGAIN)
                                continue;
                        return out ? out : rv;
                } else if (rv == 0)
                        break;

                if (csum_present) {
                        ssize_t i;

                        for (i = 0; i < rv; i++)
                                io_csum += p[i];
                }

                p += rv;
                out += rv;
                count -= rv;
        }

        return out;
}

static __initdata char *message;
static void __init error(char *x)
{
        if (!message)
                message = x;
}

#define panic_show_mem(fmt, ...) \
        ({ show_mem(); panic(fmt, ##__VA_ARGS__); })

/* link hash */

#define N_ALIGN(len) ((((len) + 1) & ~3) + 2)

static __initdata struct hash {
        int ino, minor, major;
        umode_t mode;
        struct hash *next;
        char name[N_ALIGN(PATH_MAX)];
} *head[32];
static __initdata bool hardlink_seen;

static inline int hash(int major, int minor, int ino)
{
        unsigned long tmp = ino + minor + (major << 3);
        tmp += tmp >> 5;
        return tmp & 31;
}

static char __init *find_link(int major, int minor, int ino,
                              umode_t mode, char *name)
{
        struct hash **p, *q;
        for (p = head + hash(major, minor, ino); *p; p = &(*p)->next) {
                if ((*p)->ino != ino)
                        continue;
                if ((*p)->minor != minor)
                        continue;
                if ((*p)->major != major)
                        continue;
                if (((*p)->mode ^ mode) & S_IFMT)
                        continue;
                return (*p)->name;
        }
        q = kmalloc_obj(struct hash);
        if (!q)
                panic_show_mem("can't allocate link hash entry");
        q->major = major;
        q->minor = minor;
        q->ino = ino;
        q->mode = mode;
        strscpy(q->name, name);
        q->next = NULL;
        *p = q;
        hardlink_seen = true;
        return NULL;
}

static void __init free_hash(void)
{
        struct hash **p, *q;
        for (p = head; hardlink_seen && p < head + 32; p++) {
                while (*p) {
                        q = *p;
                        *p = q->next;
                        kfree(q);
                }
        }
        hardlink_seen = false;
}

#ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
static void __init do_utime(char *filename, time64_t mtime)
{
        struct timespec64 t[2] = { { .tv_sec = mtime }, { .tv_sec = mtime } };
        init_utimes(filename, t);
}

static void __init do_utime_path(const struct path *path, time64_t mtime)
{
        struct timespec64 t[2] = { { .tv_sec = mtime }, { .tv_sec = mtime } };
        vfs_utimes(path, t);
}

static __initdata LIST_HEAD(dir_list);
struct dir_entry {
        struct list_head list;
        time64_t mtime;
        char name[];
};

static void __init dir_add(const char *name, size_t nlen, time64_t mtime)
{
        struct dir_entry *de;

        de = kmalloc_flex(*de, name, nlen);
        if (!de)
                panic_show_mem("can't allocate dir_entry buffer");
        INIT_LIST_HEAD(&de->list);
        strscpy(de->name, name, nlen);
        de->mtime = mtime;
        list_add(&de->list, &dir_list);
}

static void __init dir_utime(void)
{
        struct dir_entry *de, *tmp;
        list_for_each_entry_safe(de, tmp, &dir_list, list) {
                list_del(&de->list);
                do_utime(de->name, de->mtime);
                kfree(de);
        }
}
#else
static void __init do_utime(char *filename, time64_t mtime) {}
static void __init do_utime_path(const struct path *path, time64_t mtime) {}
static void __init dir_add(const char *name, size_t nlen, time64_t mtime) {}
static void __init dir_utime(void) {}
#endif

static __initdata time64_t mtime;

/* cpio header parsing */

static __initdata unsigned long ino, major, minor, nlink;
static __initdata umode_t mode;
static __initdata unsigned long body_len, name_len;
static __initdata uid_t uid;
static __initdata gid_t gid;
static __initdata unsigned rdev;
static __initdata u32 hdr_csum;

static void __init parse_header(char *s)
{
        unsigned long parsed[13];
        int i;

        for (i = 0, s += 6; i < 13; i++, s += 8)
                parsed[i] = simple_strntoul(s, NULL, 16, 8);

        ino = parsed[0];
        mode = parsed[1];
        uid = parsed[2];
        gid = parsed[3];
        nlink = parsed[4];
        mtime = parsed[5]; /* breaks in y2106 */
        body_len = parsed[6];
        major = parsed[7];
        minor = parsed[8];
        rdev = new_encode_dev(MKDEV(parsed[9], parsed[10]));
        name_len = parsed[11];
        hdr_csum = parsed[12];
}

/* FSM */

static __initdata enum state {
        Start,
        Collect,
        GotHeader,
        SkipIt,
        GotName,
        CopyFile,
        GotSymlink,
        Reset
} state, next_state;

static __initdata char *victim;
static unsigned long byte_count __initdata;
static __initdata loff_t this_header, next_header;

static inline void __init eat(unsigned n)
{
        victim += n;
        this_header += n;
        byte_count -= n;
}

static __initdata char *collected;
static long remains __initdata;
static __initdata char *collect;

static void __init read_into(char *buf, unsigned size, enum state next)
{
        if (byte_count >= size) {
                collected = victim;
                eat(size);
                state = next;
        } else {
                collect = collected = buf;
                remains = size;
                next_state = next;
                state = Collect;
        }
}

static __initdata char *header_buf, *symlink_buf, *name_buf;

static int __init do_start(void)
{
        read_into(header_buf, CPIO_HDRLEN, GotHeader);
        return 0;
}

static int __init do_collect(void)
{
        unsigned long n = remains;
        if (byte_count < n)
                n = byte_count;
        memcpy(collect, victim, n);
        eat(n);
        collect += n;
        if ((remains -= n) != 0)
                return 1;
        state = next_state;
        return 0;
}

static int __init do_header(void)
{
        if (!memcmp(collected, "070701", 6)) {
                csum_present = false;
        } else if (!memcmp(collected, "070702", 6)) {
                csum_present = true;
        } else {
                if (memcmp(collected, "070707", 6) == 0)
                        error("incorrect cpio method used: use -H newc option");
                else
                        error("no cpio magic");
                return 1;
        }
        parse_header(collected);
        next_header = this_header + N_ALIGN(name_len) + body_len;
        next_header = (next_header + 3) & ~3;
        state = SkipIt;
        if (name_len <= 0 || name_len > PATH_MAX)
                return 0;
        if (S_ISLNK(mode)) {
                if (body_len > PATH_MAX)
                        return 0;
                collect = collected = symlink_buf;
                remains = N_ALIGN(name_len) + body_len;
                next_state = GotSymlink;
                state = Collect;
                return 0;
        }
        if (S_ISREG(mode) || !body_len)
                read_into(name_buf, N_ALIGN(name_len), GotName);
        return 0;
}

static int __init do_skip(void)
{
        if (this_header + byte_count < next_header) {
                eat(byte_count);
                return 1;
        } else {
                eat(next_header - this_header);
                state = next_state;
                return 0;
        }
}

static int __init do_reset(void)
{
        while (byte_count && *victim == '\0')
                eat(1);
        if (byte_count && (this_header & 3))
                error("broken padding");
        return 1;
}

static void __init clean_path(char *path, umode_t fmode)
{
        struct kstat st;

        if (!init_stat(path, &st, AT_SYMLINK_NOFOLLOW) &&
            (st.mode ^ fmode) & S_IFMT) {
                if (S_ISDIR(st.mode))
                        init_rmdir(path);
                else
                        init_unlink(path);
        }
}

static int __init maybe_link(void)
{
        if (nlink >= 2) {
                char *old = find_link(major, minor, ino, mode, collected);
                if (old) {
                        clean_path(collected, 0);
                        return (init_link(old, collected) < 0) ? -1 : 1;
                }
        }
        return 0;
}

static __initdata struct file *wfile;
static __initdata loff_t wfile_pos;

static int __init do_name(void)
{
        state = SkipIt;
        next_state = Reset;

        /* name_len > 0 && name_len <= PATH_MAX checked in do_header */
        if (collected[name_len - 1] != '\0') {
                pr_err("initramfs name without nulterm: %.*s\n",
                       (int)name_len, collected);
                error("malformed archive");
                return 1;
        }

        if (strcmp(collected, "TRAILER!!!") == 0) {
                free_hash();
                return 0;
        }
        clean_path(collected, mode);
        if (S_ISREG(mode)) {
                int ml = maybe_link();
                if (ml >= 0) {
                        int openflags = O_WRONLY|O_CREAT|O_LARGEFILE;
                        if (ml != 1)
                                openflags |= O_TRUNC;
                        wfile = filp_open(collected, openflags, mode);
                        if (IS_ERR(wfile))
                                return 0;
                        wfile_pos = 0;
                        io_csum = 0;

                        vfs_fchown(wfile, uid, gid);
                        vfs_fchmod(wfile, mode);
                        if (body_len)
                                vfs_truncate(&wfile->f_path, body_len);
                        state = CopyFile;
                }
        } else if (S_ISDIR(mode)) {
                init_mkdir(collected, mode);
                init_chown(collected, uid, gid, 0);
                init_chmod(collected, mode);
                dir_add(collected, name_len, mtime);
        } else if (S_ISBLK(mode) || S_ISCHR(mode) ||
                   S_ISFIFO(mode) || S_ISSOCK(mode)) {
                if (maybe_link() == 0) {
                        init_mknod(collected, mode, rdev);
                        init_chown(collected, uid, gid, 0);
                        init_chmod(collected, mode);
                        do_utime(collected, mtime);
                }
        }
        return 0;
}

static int __init do_copy(void)
{
        if (byte_count >= body_len) {
                if (xwrite(wfile, victim, body_len, &wfile_pos) != body_len)
                        error("write error");

                do_utime_path(&wfile->f_path, mtime);
                fput(wfile);
                if (csum_present && io_csum != hdr_csum)
                        error("bad data checksum");
                eat(body_len);
                state = SkipIt;
                return 0;
        } else {
                if (xwrite(wfile, victim, byte_count, &wfile_pos) != byte_count)
                        error("write error");
                body_len -= byte_count;
                eat(byte_count);
                return 1;
        }
}

static int __init do_symlink(void)
{
        if (collected[name_len - 1] != '\0') {
                pr_err("initramfs symlink without nulterm: %.*s\n",
                       (int)name_len, collected);
                error("malformed archive");
                return 1;
        }
        collected[N_ALIGN(name_len) + body_len] = '\0';
        clean_path(collected, 0);
        init_symlink(collected + N_ALIGN(name_len), collected);
        init_chown(collected, uid, gid, AT_SYMLINK_NOFOLLOW);
        do_utime(collected, mtime);
        state = SkipIt;
        next_state = Reset;
        return 0;
}

static __initdata int (*actions[])(void) = {
        [Start]         = do_start,
        [Collect]       = do_collect,
        [GotHeader]     = do_header,
        [SkipIt]        = do_skip,
        [GotName]       = do_name,
        [CopyFile]      = do_copy,
        [GotSymlink]    = do_symlink,
        [Reset]         = do_reset,
};

static long __init write_buffer(char *buf, unsigned long len)
{
        byte_count = len;
        victim = buf;

        while (!actions[state]())
                ;
        return len - byte_count;
}

static long __init flush_buffer(void *bufv, unsigned long len)
{
        char *buf = bufv;
        long written;
        long origLen = len;
        if (message)
                return -1;
        while ((written = write_buffer(buf, len)) < len && !message) {
                char c = buf[written];
                if (c == '0') {
                        buf += written;
                        len -= written;
                        state = Start;
                } else if (c == 0) {
                        buf += written;
                        len -= written;
                        state = Reset;
                } else
                        error("junk within compressed archive");
        }
        return origLen;
}

static unsigned long my_inptr __initdata; /* index of next byte to be processed in inbuf */

#include <linux/decompress/generic.h>

/**
 * unpack_to_rootfs - decompress and extract an initramfs archive
 * @buf: input initramfs archive to extract
 * @len: length of initramfs data to process
 *
 * Returns: NULL for success or an error message string
 *
 * This symbol shouldn't be used externally. It's available for unit tests.
 */
char * __init unpack_to_rootfs(char *buf, unsigned long len)
{
        long written;
        decompress_fn decompress;
        const char *compress_name;
        struct {
                char header[CPIO_HDRLEN];
                char symlink[PATH_MAX + N_ALIGN(PATH_MAX) + 1];
                char name[N_ALIGN(PATH_MAX)];
        } *bufs = kmalloc_obj(*bufs);

        if (!bufs)
                panic_show_mem("can't allocate buffers");

        header_buf = bufs->header;
        symlink_buf = bufs->symlink;
        name_buf = bufs->name;

        state = Start;
        this_header = 0;
        message = NULL;
        while (!message && len) {
                loff_t saved_offset = this_header;
                if (*buf == '0' && !(this_header & 3)) {
                        state = Start;
                        written = write_buffer(buf, len);
                        buf += written;
                        len -= written;
                        continue;
                }
                if (!*buf) {
                        buf++;
                        len--;
                        this_header++;
                        continue;
                }
                this_header = 0;
                decompress = decompress_method(buf, len, &compress_name);
                pr_debug("Detected %s compressed data\n", compress_name);
                if (decompress) {
                        int res = decompress(buf, len, NULL, flush_buffer, NULL,
                                   &my_inptr, error);
                        if (res)
                                error("decompressor failed");
                } else if (compress_name) {
                        pr_err("compression method %s not configured\n",
                               compress_name);
                        error("decompressor failed");
                } else
                        error("invalid magic at start of compressed archive");
                if (state != Reset)
                        error("junk at the end of compressed archive");
                this_header = saved_offset + my_inptr;
                buf += my_inptr;
                len -= my_inptr;
        }
        dir_utime();
        /* free any hardlink state collected without optional TRAILER!!! */
        free_hash();
        kfree(bufs);
        return message;
}

static int __initdata do_retain_initrd;

static int __init retain_initrd_param(char *str)
{
        if (*str)
                return 0;
        do_retain_initrd = 1;
        return 1;
}
__setup("retain_initrd", retain_initrd_param);

#ifdef CONFIG_ARCH_HAS_KEEPINITRD
static int __init keepinitrd_setup(char *__unused)
{
        do_retain_initrd = 1;
        return 1;
}
__setup("keepinitrd", keepinitrd_setup);
#endif

static bool __initdata initramfs_async = true;
static int __init initramfs_async_setup(char *str)
{
        return kstrtobool(str, &initramfs_async) == 0;
}
__setup("initramfs_async=", initramfs_async_setup);

extern char __initramfs_start[];
extern unsigned long __initramfs_size;
#include <linux/initrd.h>
#include <linux/kexec.h>

static BIN_ATTR(initrd, 0440, sysfs_bin_attr_simple_read, NULL, 0);

void __init reserve_initrd_mem(void)
{
        phys_addr_t start;
        unsigned long size;

        /* Ignore the virtul address computed during device tree parsing */
        initrd_start = initrd_end = 0;

        if (!phys_initrd_size)
                return;
        /*
         * Round the memory region to page boundaries as per free_initrd_mem()
         * This allows us to detect whether the pages overlapping the initrd
         * are in use, but more importantly, reserves the entire set of pages
         * as we don't want these pages allocated for other purposes.
         */
        start = round_down(phys_initrd_start, PAGE_SIZE);
        size = phys_initrd_size + (phys_initrd_start - start);
        size = round_up(size, PAGE_SIZE);

        if (!memblock_is_region_memory(start, size)) {
                pr_err("INITRD: 0x%08llx+0x%08lx is not a memory region",
                       (u64)start, size);
                goto disable;
        }

        if (memblock_is_region_reserved(start, size)) {
                pr_err("INITRD: 0x%08llx+0x%08lx overlaps in-use memory region\n",
                       (u64)start, size);
                goto disable;
        }

        memblock_reserve(start, size);
        /* Now convert initrd to virtual addresses */
        initrd_start = (unsigned long)__va(phys_initrd_start);
        initrd_end = initrd_start + phys_initrd_size;
        initrd_below_start_ok = 1;

        return;
disable:
        pr_cont(" - disabling initrd\n");
        initrd_start = 0;
        initrd_end = 0;
}

void __weak __init free_initrd_mem(unsigned long start, unsigned long end)
{
#ifdef CONFIG_ARCH_KEEP_MEMBLOCK
        unsigned long aligned_start = ALIGN_DOWN(start, PAGE_SIZE);
        unsigned long aligned_end = ALIGN(end, PAGE_SIZE);

        memblock_free((void *)aligned_start, aligned_end - aligned_start);
#endif

        free_reserved_area((void *)start, (void *)end, POISON_FREE_INITMEM,
                        "initrd");
}

#ifdef CONFIG_CRASH_RESERVE
static bool __init kexec_free_initrd(void)
{
        unsigned long crashk_start = (unsigned long)__va(crashk_res.start);
        unsigned long crashk_end   = (unsigned long)__va(crashk_res.end);

        /*
         * If the initrd region is overlapped with crashkernel reserved region,
         * free only memory that is not part of crashkernel region.
         */
        if (initrd_start >= crashk_end || initrd_end <= crashk_start)
                return false;

        /*
         * Initialize initrd memory region since the kexec boot does not do.
         */
        memset((void *)initrd_start, 0, initrd_end - initrd_start);
        if (initrd_start < crashk_start)
                free_initrd_mem(initrd_start, crashk_start);
        if (initrd_end > crashk_end)
                free_initrd_mem(crashk_end, initrd_end);
        return true;
}
#else
static inline bool kexec_free_initrd(void)
{
        return false;
}
#endif /* CONFIG_KEXEC_CORE */

#ifdef CONFIG_BLK_DEV_RAM
static void __init populate_initrd_image(char *err)
{
        ssize_t written;
        struct file *file;
        loff_t pos = 0;

        printk(KERN_INFO "rootfs image is not initramfs (%s); looks like an initrd\n",
                        err);
        file = filp_open("/initrd.image", O_WRONLY|O_CREAT|O_LARGEFILE, 0700);
        if (IS_ERR(file))
                return;

        written = xwrite(file, (char *)initrd_start, initrd_end - initrd_start,
                        &pos);
        if (written != initrd_end - initrd_start)
                pr_err("/initrd.image: incomplete write (%zd != %ld)\n",
                       written, initrd_end - initrd_start);
        fput(file);
}
#endif /* CONFIG_BLK_DEV_RAM */

static void __init do_populate_rootfs(void *unused, async_cookie_t cookie)
{
        /* Load the built in initramfs */
        char *err = unpack_to_rootfs(__initramfs_start, __initramfs_size);
        if (err)
                panic_show_mem("%s", err); /* Failed to decompress INTERNAL initramfs */

        if (!initrd_start || IS_ENABLED(CONFIG_INITRAMFS_FORCE))
                goto done;

        if (IS_ENABLED(CONFIG_BLK_DEV_RAM))
                printk(KERN_INFO "Trying to unpack rootfs image as initramfs...\n");
        else
                printk(KERN_INFO "Unpacking initramfs...\n");

        err = unpack_to_rootfs((char *)initrd_start, initrd_end - initrd_start);
        if (err) {
#ifdef CONFIG_BLK_DEV_RAM
                populate_initrd_image(err);
#else
                printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
#endif
        }

done:
        security_initramfs_populated();

        /*
         * If the initrd region is overlapped with crashkernel reserved region,
         * free only memory that is not part of crashkernel region.
         */
        if (!do_retain_initrd && initrd_start && !kexec_free_initrd()) {
                free_initrd_mem(initrd_start, initrd_end);
        } else if (do_retain_initrd && initrd_start) {
                bin_attr_initrd.size = initrd_end - initrd_start;
                bin_attr_initrd.private = (void *)initrd_start;
                if (sysfs_create_bin_file(firmware_kobj, &bin_attr_initrd))
                        pr_err("Failed to create initrd sysfs file");
        }
        initrd_start = 0;
        initrd_end = 0;

        init_flush_fput();
}

static ASYNC_DOMAIN_EXCLUSIVE(initramfs_domain);
static async_cookie_t initramfs_cookie;

void wait_for_initramfs(void)
{
        if (!initramfs_cookie) {
                /*
                 * Something before rootfs_initcall wants to access
                 * the filesystem/initramfs. Probably a bug. Make a
                 * note, avoid deadlocking the machine, and let the
                 * caller's access fail as it used to.
                 */
                pr_warn_once("wait_for_initramfs() called before rootfs_initcalls\n");
                return;
        }
        async_synchronize_cookie_domain(initramfs_cookie + 1, &initramfs_domain);
}
EXPORT_SYMBOL_GPL(wait_for_initramfs);

static int __init populate_rootfs(void)
{
        initramfs_cookie = async_schedule_domain(do_populate_rootfs, NULL,
                                                 &initramfs_domain);
        usermodehelper_enable();
        if (!initramfs_async)
                wait_for_initramfs();
        return 0;
}
rootfs_initcall(populate_rootfs);