initramfs.c

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/*
 * Many of the syscalls used in this file expect some of the arguments
 * to be __user pointers not __kernel pointers.  To limit the sparse
 * noise, turn off sparse checking for this file.
 */
#ifdef __CHECKER__
#undef __CHECKER__
#warning "Sparse checking disabled for this file"
#endif

#include <linux/init.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>

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

/* 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 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(sizeof(struct hash), GFP_KERNEL);
    if (!q)
        panic("can't allocate link hash entry");
    q->major = major;
    q->minor = minor;
    q->ino = ino;
    q->mode = mode;
    strcpy(q->name, name);
    q->next = NULL;
    *p = q;
    return NULL;
}

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

static long __init do_utime(char *filename, time_t mtime)
{
    struct timespec t[2];

    t[0].tv_sec = mtime;
    t[0].tv_nsec = 0;
    t[1].tv_sec = mtime;
    t[1].tv_nsec = 0;

    return do_utimes(AT_FDCWD, filename, t, AT_SYMLINK_NOFOLLOW);
}

static __initdata LIST_HEAD(dir_list);
struct dir_entry {
    struct list_head list;
    char *name;
    time_t mtime;
};

static void __init dir_add(const char *name, time_t mtime)
{
    struct dir_entry *de = kmalloc(sizeof(struct dir_entry), GFP_KERNEL);
    if (!de)
        panic("can't allocate dir_entry buffer");
    INIT_LIST_HEAD(&de->list);
    de->name = kstrdup(name, GFP_KERNEL);
    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->name);
        kfree(de);
    }
}

static __initdata time_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 void __init parse_header(char *s)
{
    unsigned long parsed[12];
    char buf[9];
    int i;

    buf[8] = '\0';
    for (i = 0, s += 6; i < 12; i++, s += 8) {
        memcpy(buf, s, 8);
        parsed[i] = simple_strtoul(buf, NULL, 16);
    }
    ino = parsed[0];
    mode = parsed[1];
    uid = parsed[2];
    gid = parsed[3];
    nlink = parsed[4];
    mtime = parsed[5];
    body_len = parsed[6];
    major = parsed[7];
    minor = parsed[8];
    rdev = new_encode_dev(MKDEV(parsed[9], parsed[10]));
    name_len = parsed[11];
}

/* FSM */

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

static __initdata char *victim;
static __initdata unsigned count;
static __initdata loff_t this_header, next_header;

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

static __initdata char *vcollected;
static __initdata char *collected;
static __initdata int remains;
static __initdata char *collect;

static void __init read_into(char *buf, unsigned size, enum state next)
{
    if (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, 110, GotHeader);
    return 0;
}

static int __init do_collect(void)
{
    unsigned n = remains;
    if (count < n)
        n = 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, "070707", 6)==0) {
        error("incorrect cpio method used: use -H newc option");
        return 1;
    }
    if (memcmp(collected, "070701", 6)) {
        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 + count < next_header) {
        eat(count);
        return 1;
    } else {
        eat(next_header - this_header);
        state = next_state;
        return 0;
    }
}

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

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

static void __init clean_path(char *path, umode_t mode)
{
    struct stat st;

    if (!sys_newlstat(path, &st) && (st.st_mode^mode) & S_IFMT) {
        if (S_ISDIR(st.st_mode))
            sys_rmdir(path);
        else
            sys_unlink(path);
    }
}

static __initdata int wfd;

static int __init do_name(void)
{
    state = SkipIt;
    next_state = Reset;
    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;
            if (ml != 1)
                openflags |= O_TRUNC;
            wfd = sys_open(collected, openflags, mode);

            if (wfd >= 0) {
                sys_fchown(wfd, uid, gid);
                sys_fchmod(wfd, mode);
                if (body_len)
                    sys_ftruncate(wfd, body_len);
                vcollected = kstrdup(collected, GFP_KERNEL);
                state = CopyFile;
            }
        }
    } else if (S_ISDIR(mode)) {
        sys_mkdir(collected, mode);
        sys_chown(collected, uid, gid);
        sys_chmod(collected, mode);
        dir_add(collected, mtime);
    } else if (S_ISBLK(mode) || S_ISCHR(mode) ||
           S_ISFIFO(mode) || S_ISSOCK(mode)) {
        if (maybe_link() == 0) {
            sys_mknod(collected, mode, rdev);
            sys_chown(collected, uid, gid);
            sys_chmod(collected, mode);
            do_utime(collected, mtime);
        }
    }
    return 0;
}

static int __init do_copy(void)
{
    if (count >= body_len) {
        sys_write(wfd, victim, body_len);
        sys_close(wfd);
        do_utime(vcollected, mtime);
        kfree(vcollected);
        eat(body_len);
        state = SkipIt;
        return 0;
    } else {
        sys_write(wfd, victim, count);
        body_len -= count;
        eat(count);
        return 1;
    }
}

static int __init do_symlink(void)
{
    collected[N_ALIGN(name_len) + body_len] = '\0';
    clean_path(collected, 0);
    sys_symlink(collected + N_ALIGN(name_len), collected);
    sys_lchown(collected, uid, gid);
    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 int __init write_buffer(char *buf, unsigned len)
{
    count = len;
    victim = buf;

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

static int __init flush_buffer(void *bufv, unsigned len)
{
    char *buf = (char *) bufv;
    int written;
    int 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 in compressed archive");
    }
    return origLen;
}

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

#include <linux/decompress/generic.h>

static char * __init unpack_to_rootfs(char *buf, unsigned len)
{
    int written, res;
    decompress_fn decompress;
    const char *compress_name;
    static __initdata char msg_buf[64];

    header_buf = kmalloc(110, GFP_KERNEL);
    symlink_buf = kmalloc(PATH_MAX + N_ALIGN(PATH_MAX) + 1, GFP_KERNEL);
    name_buf = kmalloc(N_ALIGN(PATH_MAX), GFP_KERNEL);

    if (!header_buf || !symlink_buf || !name_buf)
        panic("can't allocate buffers");

    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);
        if (decompress) {
            res = decompress(buf, len, NULL, flush_buffer, NULL,
                   &my_inptr, error);
            if (res)
                error("decompressor failed");
        } else if (compress_name) {
            if (!message) {
                snprintf(msg_buf, sizeof msg_buf,
                     "compression method %s not configured",
                     compress_name);
                message = msg_buf;
            }
        } else
            error("junk in compressed archive");
        if (state != Reset)
            error("junk in compressed archive");
        this_header = saved_offset + my_inptr;
        buf += my_inptr;
        len -= my_inptr;
    }
    dir_utime();
    kfree(name_buf);
    kfree(symlink_buf);
    kfree(header_buf);
    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);

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

static void __init free_initrd(void)
{
#ifdef CONFIG_KEXEC
    unsigned long crashk_start = (unsigned long)__va(crashk_res.start);
    unsigned long crashk_end   = (unsigned long)__va(crashk_res.end);
#endif
    if (do_retain_initrd)
        goto skip;

#ifdef CONFIG_KEXEC
    /*
     * 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) {
        /*
         * 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);
    } else
#endif
        free_initrd_mem(initrd_start, initrd_end);
skip:
    initrd_start = 0;
    initrd_end = 0;
}

#ifdef CONFIG_BLK_DEV_RAM
#define BUF_SIZE 1024
static void __init clean_rootfs(void)
{
    int fd;
    void *buf;
    struct linux_dirent64 *dirp;
    int num;

    fd = sys_open("/", O_RDONLY, 0);
    WARN_ON(fd < 0);
    if (fd < 0)
        return;
    buf = kzalloc(BUF_SIZE, GFP_KERNEL);
    WARN_ON(!buf);
    if (!buf) {
        sys_close(fd);
        return;
    }

    dirp = buf;
    num = sys_getdents64(fd, dirp, BUF_SIZE);
    while (num > 0) {
        while (num > 0) {
            struct stat st;
            int ret;

            ret = sys_newlstat(dirp->d_name, &st);
            WARN_ON_ONCE(ret);
            if (!ret) {
                if (S_ISDIR(st.st_mode))
                    sys_rmdir(dirp->d_name);
                else
                    sys_unlink(dirp->d_name);
            }

            num -= dirp->d_reclen;
            dirp = (void *)dirp + dirp->d_reclen;
        }
        dirp = buf;
        memset(buf, 0, BUF_SIZE);
        num = sys_getdents64(fd, dirp, BUF_SIZE);
    }

    sys_close(fd);
    kfree(buf);
}
#endif

static int __init populate_rootfs(void)
{
    char *err = unpack_to_rootfs(__initramfs_start, __initramfs_size);
    if (err)
        panic(err); /* Failed to decompress INTERNAL initramfs */
    if (initrd_start) {
#ifdef CONFIG_BLK_DEV_RAM
        int fd;
        printk(KERN_INFO "Trying to unpack rootfs image as initramfs...\n");
        err = unpack_to_rootfs((char *)initrd_start,
            initrd_end - initrd_start);
        if (!err) {
            free_initrd();
            return 0;
        } else {
            clean_rootfs();
            unpack_to_rootfs(__initramfs_start, __initramfs_size);
        }
        printk(KERN_INFO "rootfs image is not initramfs (%s)"
                "; looks like an initrd\n", err);
        fd = sys_open("/initrd.image",
                  O_WRONLY|O_CREAT, 0700);
        if (fd >= 0) {
            sys_write(fd, (char *)initrd_start,
                    initrd_end - initrd_start);
            sys_close(fd);
            free_initrd();
        }
#else
        printk(KERN_INFO "Unpacking initramfs...\n");
        err = unpack_to_rootfs((char *)initrd_start,
            initrd_end - initrd_start);
        if (err)
            printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
        free_initrd();
#endif
    }
    return 0;
}
rootfs_initcall(populate_rootfs);