linux/init/do_mounts_rd.c
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   1// SPDX-License-Identifier: GPL-2.0
   2#include <linux/kernel.h>
   3#include <linux/fs.h>
   4#include <linux/minix_fs.h>
   5#include <linux/ext2_fs.h>
   6#include <linux/romfs_fs.h>
   7#include <uapi/linux/cramfs_fs.h>
   8#include <linux/initrd.h>
   9#include <linux/string.h>
  10#include <linux/slab.h>
  11
  12#include "do_mounts.h"
  13#include "../fs/squashfs/squashfs_fs.h"
  14
  15#include <linux/decompress/generic.h>
  16
  17
  18int __initdata rd_prompt = 1;/* 1 = prompt for RAM disk, 0 = don't prompt */
  19
  20static int __init prompt_ramdisk(char *str)
  21{
  22        rd_prompt = simple_strtol(str,NULL,0) & 1;
  23        return 1;
  24}
  25__setup("prompt_ramdisk=", prompt_ramdisk);
  26
  27int __initdata rd_image_start;          /* starting block # of image */
  28
  29static int __init ramdisk_start_setup(char *str)
  30{
  31        rd_image_start = simple_strtol(str,NULL,0);
  32        return 1;
  33}
  34__setup("ramdisk_start=", ramdisk_start_setup);
  35
  36static int __init crd_load(int in_fd, int out_fd, decompress_fn deco);
  37
  38/*
  39 * This routine tries to find a RAM disk image to load, and returns the
  40 * number of blocks to read for a non-compressed image, 0 if the image
  41 * is a compressed image, and -1 if an image with the right magic
  42 * numbers could not be found.
  43 *
  44 * We currently check for the following magic numbers:
  45 *      minix
  46 *      ext2
  47 *      romfs
  48 *      cramfs
  49 *      squashfs
  50 *      gzip
  51 *      bzip2
  52 *      lzma
  53 *      xz
  54 *      lzo
  55 *      lz4
  56 */
  57static int __init
  58identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
  59{
  60        const int size = 512;
  61        struct minix_super_block *minixsb;
  62        struct romfs_super_block *romfsb;
  63        struct cramfs_super *cramfsb;
  64        struct squashfs_super_block *squashfsb;
  65        int nblocks = -1;
  66        unsigned char *buf;
  67        const char *compress_name;
  68        unsigned long n;
  69
  70        buf = kmalloc(size, GFP_KERNEL);
  71        if (!buf)
  72                return -ENOMEM;
  73
  74        minixsb = (struct minix_super_block *) buf;
  75        romfsb = (struct romfs_super_block *) buf;
  76        cramfsb = (struct cramfs_super *) buf;
  77        squashfsb = (struct squashfs_super_block *) buf;
  78        memset(buf, 0xe5, size);
  79
  80        /*
  81         * Read block 0 to test for compressed kernel
  82         */
  83        ksys_lseek(fd, start_block * BLOCK_SIZE, 0);
  84        ksys_read(fd, buf, size);
  85
  86        *decompressor = decompress_method(buf, size, &compress_name);
  87        if (compress_name) {
  88                printk(KERN_NOTICE "RAMDISK: %s image found at block %d\n",
  89                       compress_name, start_block);
  90                if (!*decompressor)
  91                        printk(KERN_EMERG
  92                               "RAMDISK: %s decompressor not configured!\n",
  93                               compress_name);
  94                nblocks = 0;
  95                goto done;
  96        }
  97
  98        /* romfs is at block zero too */
  99        if (romfsb->word0 == ROMSB_WORD0 &&
 100            romfsb->word1 == ROMSB_WORD1) {
 101                printk(KERN_NOTICE
 102                       "RAMDISK: romfs filesystem found at block %d\n",
 103                       start_block);
 104                nblocks = (ntohl(romfsb->size)+BLOCK_SIZE-1)>>BLOCK_SIZE_BITS;
 105                goto done;
 106        }
 107
 108        if (cramfsb->magic == CRAMFS_MAGIC) {
 109                printk(KERN_NOTICE
 110                       "RAMDISK: cramfs filesystem found at block %d\n",
 111                       start_block);
 112                nblocks = (cramfsb->size + BLOCK_SIZE - 1) >> BLOCK_SIZE_BITS;
 113                goto done;
 114        }
 115
 116        /* squashfs is at block zero too */
 117        if (le32_to_cpu(squashfsb->s_magic) == SQUASHFS_MAGIC) {
 118                printk(KERN_NOTICE
 119                       "RAMDISK: squashfs filesystem found at block %d\n",
 120                       start_block);
 121                nblocks = (le64_to_cpu(squashfsb->bytes_used) + BLOCK_SIZE - 1)
 122                         >> BLOCK_SIZE_BITS;
 123                goto done;
 124        }
 125
 126        /*
 127         * Read 512 bytes further to check if cramfs is padded
 128         */
 129        ksys_lseek(fd, start_block * BLOCK_SIZE + 0x200, 0);
 130        ksys_read(fd, buf, size);
 131
 132        if (cramfsb->magic == CRAMFS_MAGIC) {
 133                printk(KERN_NOTICE
 134                       "RAMDISK: cramfs filesystem found at block %d\n",
 135                       start_block);
 136                nblocks = (cramfsb->size + BLOCK_SIZE - 1) >> BLOCK_SIZE_BITS;
 137                goto done;
 138        }
 139
 140        /*
 141         * Read block 1 to test for minix and ext2 superblock
 142         */
 143        ksys_lseek(fd, (start_block+1) * BLOCK_SIZE, 0);
 144        ksys_read(fd, buf, size);
 145
 146        /* Try minix */
 147        if (minixsb->s_magic == MINIX_SUPER_MAGIC ||
 148            minixsb->s_magic == MINIX_SUPER_MAGIC2) {
 149                printk(KERN_NOTICE
 150                       "RAMDISK: Minix filesystem found at block %d\n",
 151                       start_block);
 152                nblocks = minixsb->s_nzones << minixsb->s_log_zone_size;
 153                goto done;
 154        }
 155
 156        /* Try ext2 */
 157        n = ext2_image_size(buf);
 158        if (n) {
 159                printk(KERN_NOTICE
 160                       "RAMDISK: ext2 filesystem found at block %d\n",
 161                       start_block);
 162                nblocks = n;
 163                goto done;
 164        }
 165
 166        printk(KERN_NOTICE
 167               "RAMDISK: Couldn't find valid RAM disk image starting at %d.\n",
 168               start_block);
 169
 170done:
 171        ksys_lseek(fd, start_block * BLOCK_SIZE, 0);
 172        kfree(buf);
 173        return nblocks;
 174}
 175
 176int __init rd_load_image(char *from)
 177{
 178        int res = 0;
 179        int in_fd, out_fd;
 180        unsigned long rd_blocks, devblocks;
 181        int nblocks, i, disk;
 182        char *buf = NULL;
 183        unsigned short rotate = 0;
 184        decompress_fn decompressor = NULL;
 185#if !defined(CONFIG_S390)
 186        char rotator[4] = { '|' , '/' , '-' , '\\' };
 187#endif
 188
 189        out_fd = ksys_open("/dev/ram", O_RDWR, 0);
 190        if (out_fd < 0)
 191                goto out;
 192
 193        in_fd = ksys_open(from, O_RDONLY, 0);
 194        if (in_fd < 0)
 195                goto noclose_input;
 196
 197        nblocks = identify_ramdisk_image(in_fd, rd_image_start, &decompressor);
 198        if (nblocks < 0)
 199                goto done;
 200
 201        if (nblocks == 0) {
 202                if (crd_load(in_fd, out_fd, decompressor) == 0)
 203                        goto successful_load;
 204                goto done;
 205        }
 206
 207        /*
 208         * NOTE NOTE: nblocks is not actually blocks but
 209         * the number of kibibytes of data to load into a ramdisk.
 210         */
 211        if (ksys_ioctl(out_fd, BLKGETSIZE, (unsigned long)&rd_blocks) < 0)
 212                rd_blocks = 0;
 213        else
 214                rd_blocks >>= 1;
 215
 216        if (nblocks > rd_blocks) {
 217                printk("RAMDISK: image too big! (%dKiB/%ldKiB)\n",
 218                       nblocks, rd_blocks);
 219                goto done;
 220        }
 221
 222        /*
 223         * OK, time to copy in the data
 224         */
 225        if (ksys_ioctl(in_fd, BLKGETSIZE, (unsigned long)&devblocks) < 0)
 226                devblocks = 0;
 227        else
 228                devblocks >>= 1;
 229
 230        if (strcmp(from, "/initrd.image") == 0)
 231                devblocks = nblocks;
 232
 233        if (devblocks == 0) {
 234                printk(KERN_ERR "RAMDISK: could not determine device size\n");
 235                goto done;
 236        }
 237
 238        buf = kmalloc(BLOCK_SIZE, GFP_KERNEL);
 239        if (!buf) {
 240                printk(KERN_ERR "RAMDISK: could not allocate buffer\n");
 241                goto done;
 242        }
 243
 244        printk(KERN_NOTICE "RAMDISK: Loading %dKiB [%ld disk%s] into ram disk... ",
 245                nblocks, ((nblocks-1)/devblocks)+1, nblocks>devblocks ? "s" : "");
 246        for (i = 0, disk = 1; i < nblocks; i++) {
 247                if (i && (i % devblocks == 0)) {
 248                        pr_cont("done disk #%d.\n", disk++);
 249                        rotate = 0;
 250                        if (ksys_close(in_fd)) {
 251                                printk("Error closing the disk.\n");
 252                                goto noclose_input;
 253                        }
 254                        change_floppy("disk #%d", disk);
 255                        in_fd = ksys_open(from, O_RDONLY, 0);
 256                        if (in_fd < 0)  {
 257                                printk("Error opening disk.\n");
 258                                goto noclose_input;
 259                        }
 260                        printk("Loading disk #%d... ", disk);
 261                }
 262                ksys_read(in_fd, buf, BLOCK_SIZE);
 263                ksys_write(out_fd, buf, BLOCK_SIZE);
 264#if !defined(CONFIG_S390)
 265                if (!(i % 16)) {
 266                        pr_cont("%c\b", rotator[rotate & 0x3]);
 267                        rotate++;
 268                }
 269#endif
 270        }
 271        pr_cont("done.\n");
 272
 273successful_load:
 274        res = 1;
 275done:
 276        ksys_close(in_fd);
 277noclose_input:
 278        ksys_close(out_fd);
 279out:
 280        kfree(buf);
 281        ksys_unlink("/dev/ram");
 282        return res;
 283}
 284
 285int __init rd_load_disk(int n)
 286{
 287        if (rd_prompt)
 288                change_floppy("root floppy disk to be loaded into RAM disk");
 289        create_dev("/dev/root", ROOT_DEV);
 290        create_dev("/dev/ram", MKDEV(RAMDISK_MAJOR, n));
 291        return rd_load_image("/dev/root");
 292}
 293
 294static int exit_code;
 295static int decompress_error;
 296static int crd_infd, crd_outfd;
 297
 298static long __init compr_fill(void *buf, unsigned long len)
 299{
 300        long r = ksys_read(crd_infd, buf, len);
 301        if (r < 0)
 302                printk(KERN_ERR "RAMDISK: error while reading compressed data");
 303        else if (r == 0)
 304                printk(KERN_ERR "RAMDISK: EOF while reading compressed data");
 305        return r;
 306}
 307
 308static long __init compr_flush(void *window, unsigned long outcnt)
 309{
 310        long written = ksys_write(crd_outfd, window, outcnt);
 311        if (written != outcnt) {
 312                if (decompress_error == 0)
 313                        printk(KERN_ERR
 314                               "RAMDISK: incomplete write (%ld != %ld)\n",
 315                               written, outcnt);
 316                decompress_error = 1;
 317                return -1;
 318        }
 319        return outcnt;
 320}
 321
 322static void __init error(char *x)
 323{
 324        printk(KERN_ERR "%s\n", x);
 325        exit_code = 1;
 326        decompress_error = 1;
 327}
 328
 329static int __init crd_load(int in_fd, int out_fd, decompress_fn deco)
 330{
 331        int result;
 332        crd_infd = in_fd;
 333        crd_outfd = out_fd;
 334
 335        if (!deco) {
 336                pr_emerg("Invalid ramdisk decompression routine.  "
 337                         "Select appropriate config option.\n");
 338                panic("Could not decompress initial ramdisk image.");
 339        }
 340
 341        result = deco(NULL, 0, compr_fill, compr_flush, NULL, NULL, error);
 342        if (decompress_error)
 343                result = 1;
 344        return result;
 345}
 346