the-tree/init/do_mounts_rd.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #include <linux/kernel.h>
0003 #include <linux/fs.h>
0004 #include <linux/minix_fs.h>
0005 #include <linux/ext2_fs.h>
0006 #include <linux/romfs_fs.h>
0007 #include <uapi/linux/cramfs_fs.h>
0008 #include <linux/initrd.h>
0009 #include <linux/string.h>
0010 #include <linux/slab.h>
0011
0012 #include "do_mounts.h"
0013 #include "../fs/squashfs/squashfs_fs.h"
0014
0015 #include <linux/decompress/generic.h>
0016
0017 static struct file *in_file, *out_file;
0018 static loff_t in_pos, out_pos;
0019
0020 static int __init prompt_ramdisk(char *str)
0021 {
0022     pr_warn("ignoring the deprecated prompt_ramdisk= option\n");
0023     return 1;
0024 }
0025 __setup("prompt_ramdisk=", prompt_ramdisk);
0026
0027 int __initdata rd_image_start;      /* starting block # of image */
0028
0029 static int __init ramdisk_start_setup(char *str)
0030 {
0031     rd_image_start = simple_strtol(str,NULL,0);
0032     return 1;
0033 }
0034 __setup("ramdisk_start=", ramdisk_start_setup);
0035
0036 static int __init crd_load(decompress_fn deco);
0037
0038 /*
0039  * This routine tries to find a RAM disk image to load, and returns the
0040  * number of blocks to read for a non-compressed image, 0 if the image
0041  * is a compressed image, and -1 if an image with the right magic
0042  * numbers could not be found.
0043  *
0044  * We currently check for the following magic numbers:
0045  *  minix
0046  *  ext2
0047  *  romfs
0048  *  cramfs
0049  *  squashfs
0050  *  gzip
0051  *  bzip2
0052  *  lzma
0053  *  xz
0054  *  lzo
0055  *  lz4
0056  */
0057 static int __init
0058 identify_ramdisk_image(struct file *file, loff_t pos,
0059         decompress_fn *decompressor)
0060 {
0061     const int size = 512;
0062     struct minix_super_block *minixsb;
0063     struct romfs_super_block *romfsb;
0064     struct cramfs_super *cramfsb;
0065     struct squashfs_super_block *squashfsb;
0066     int nblocks = -1;
0067     unsigned char *buf;
0068     const char *compress_name;
0069     unsigned long n;
0070     int start_block = rd_image_start;
0071
0072     buf = kmalloc(size, GFP_KERNEL);
0073     if (!buf)
0074         return -ENOMEM;
0075
0076     minixsb = (struct minix_super_block *) buf;
0077     romfsb = (struct romfs_super_block *) buf;
0078     cramfsb = (struct cramfs_super *) buf;
0079     squashfsb = (struct squashfs_super_block *) buf;
0080     memset(buf, 0xe5, size);
0081
0082     /*
0083      * Read block 0 to test for compressed kernel
0084      */
0085     pos = start_block * BLOCK_SIZE;
0086     kernel_read(file, buf, size, &pos);
0087
0088     *decompressor = decompress_method(buf, size, &compress_name);
0089     if (compress_name) {
0090         printk(KERN_NOTICE "RAMDISK: %s image found at block %d\n",
0091                compress_name, start_block);
0092         if (!*decompressor)
0093             printk(KERN_EMERG
0094                    "RAMDISK: %s decompressor not configured!\n",
0095                    compress_name);
0096         nblocks = 0;
0097         goto done;
0098     }
0099
0100     /* romfs is at block zero too */
0101     if (romfsb->word0 == ROMSB_WORD0 &&
0102         romfsb->word1 == ROMSB_WORD1) {
0103         printk(KERN_NOTICE
0104                "RAMDISK: romfs filesystem found at block %d\n",
0105                start_block);
0106         nblocks = (ntohl(romfsb->size)+BLOCK_SIZE-1)>>BLOCK_SIZE_BITS;
0107         goto done;
0108     }
0109
0110     if (cramfsb->magic == CRAMFS_MAGIC) {
0111         printk(KERN_NOTICE
0112                "RAMDISK: cramfs filesystem found at block %d\n",
0113                start_block);
0114         nblocks = (cramfsb->size + BLOCK_SIZE - 1) >> BLOCK_SIZE_BITS;
0115         goto done;
0116     }
0117
0118     /* squashfs is at block zero too */
0119     if (le32_to_cpu(squashfsb->s_magic) == SQUASHFS_MAGIC) {
0120         printk(KERN_NOTICE
0121                "RAMDISK: squashfs filesystem found at block %d\n",
0122                start_block);
0123         nblocks = (le64_to_cpu(squashfsb->bytes_used) + BLOCK_SIZE - 1)
0124              >> BLOCK_SIZE_BITS;
0125         goto done;
0126     }
0127
0128     /*
0129      * Read 512 bytes further to check if cramfs is padded
0130      */
0131     pos = start_block * BLOCK_SIZE + 0x200;
0132     kernel_read(file, buf, size, &pos);
0133
0134     if (cramfsb->magic == CRAMFS_MAGIC) {
0135         printk(KERN_NOTICE
0136                "RAMDISK: cramfs filesystem found at block %d\n",
0137                start_block);
0138         nblocks = (cramfsb->size + BLOCK_SIZE - 1) >> BLOCK_SIZE_BITS;
0139         goto done;
0140     }
0141
0142     /*
0143      * Read block 1 to test for minix and ext2 superblock
0144      */
0145     pos = (start_block + 1) * BLOCK_SIZE;
0146     kernel_read(file, buf, size, &pos);
0147
0148     /* Try minix */
0149     if (minixsb->s_magic == MINIX_SUPER_MAGIC ||
0150         minixsb->s_magic == MINIX_SUPER_MAGIC2) {
0151         printk(KERN_NOTICE
0152                "RAMDISK: Minix filesystem found at block %d\n",
0153                start_block);
0154         nblocks = minixsb->s_nzones << minixsb->s_log_zone_size;
0155         goto done;
0156     }
0157
0158     /* Try ext2 */
0159     n = ext2_image_size(buf);
0160     if (n) {
0161         printk(KERN_NOTICE
0162                "RAMDISK: ext2 filesystem found at block %d\n",
0163                start_block);
0164         nblocks = n;
0165         goto done;
0166     }
0167
0168     printk(KERN_NOTICE
0169            "RAMDISK: Couldn't find valid RAM disk image starting at %d.\n",
0170            start_block);
0171
0172 done:
0173     kfree(buf);
0174     return nblocks;
0175 }
0176
0177 static unsigned long nr_blocks(struct file *file)
0178 {
0179     struct inode *inode = file->f_mapping->host;
0180
0181     if (!S_ISBLK(inode->i_mode))
0182         return 0;
0183     return i_size_read(inode) >> 10;
0184 }
0185
0186 int __init rd_load_image(char *from)
0187 {
0188     int res = 0;
0189     unsigned long rd_blocks, devblocks;
0190     int nblocks, i;
0191     char *buf = NULL;
0192     unsigned short rotate = 0;
0193     decompress_fn decompressor = NULL;
0194 #if !defined(CONFIG_S390)
0195     char rotator[4] = { '|' , '/' , '-' , '\\' };
0196 #endif
0197
0198     out_file = filp_open("/dev/ram", O_RDWR, 0);
0199     if (IS_ERR(out_file))
0200         goto out;
0201
0202     in_file = filp_open(from, O_RDONLY, 0);
0203     if (IS_ERR(in_file))
0204         goto noclose_input;
0205
0206     in_pos = rd_image_start * BLOCK_SIZE;
0207     nblocks = identify_ramdisk_image(in_file, in_pos, &decompressor);
0208     if (nblocks < 0)
0209         goto done;
0210
0211     if (nblocks == 0) {
0212         if (crd_load(decompressor) == 0)
0213             goto successful_load;
0214         goto done;
0215     }
0216
0217     /*
0218      * NOTE NOTE: nblocks is not actually blocks but
0219      * the number of kibibytes of data to load into a ramdisk.
0220      */
0221     rd_blocks = nr_blocks(out_file);
0222     if (nblocks > rd_blocks) {
0223         printk("RAMDISK: image too big! (%dKiB/%ldKiB)\n",
0224                nblocks, rd_blocks);
0225         goto done;
0226     }
0227
0228     /*
0229      * OK, time to copy in the data
0230      */
0231     if (strcmp(from, "/initrd.image") == 0)
0232         devblocks = nblocks;
0233     else
0234         devblocks = nr_blocks(in_file);
0235
0236     if (devblocks == 0) {
0237         printk(KERN_ERR "RAMDISK: could not determine device size\n");
0238         goto done;
0239     }
0240
0241     buf = kmalloc(BLOCK_SIZE, GFP_KERNEL);
0242     if (!buf) {
0243         printk(KERN_ERR "RAMDISK: could not allocate buffer\n");
0244         goto done;
0245     }
0246
0247     printk(KERN_NOTICE "RAMDISK: Loading %dKiB [%ld disk%s] into ram disk... ",
0248         nblocks, ((nblocks-1)/devblocks)+1, nblocks>devblocks ? "s" : "");
0249     for (i = 0; i < nblocks; i++) {
0250         if (i && (i % devblocks == 0)) {
0251             pr_cont("done disk #1.\n");
0252             rotate = 0;
0253             fput(in_file);
0254             break;
0255         }
0256         kernel_read(in_file, buf, BLOCK_SIZE, &in_pos);
0257         kernel_write(out_file, buf, BLOCK_SIZE, &out_pos);
0258 #if !defined(CONFIG_S390)
0259         if (!(i % 16)) {
0260             pr_cont("%c\b", rotator[rotate & 0x3]);
0261             rotate++;
0262         }
0263 #endif
0264     }
0265     pr_cont("done.\n");
0266
0267 successful_load:
0268     res = 1;
0269 done:
0270     fput(in_file);
0271 noclose_input:
0272     fput(out_file);
0273 out:
0274     kfree(buf);
0275     init_unlink("/dev/ram");
0276     return res;
0277 }
0278
0279 int __init rd_load_disk(int n)
0280 {
0281     create_dev("/dev/root", ROOT_DEV);
0282     create_dev("/dev/ram", MKDEV(RAMDISK_MAJOR, n));
0283     return rd_load_image("/dev/root");
0284 }
0285
0286 static int exit_code;
0287 static int decompress_error;
0288
0289 static long __init compr_fill(void *buf, unsigned long len)
0290 {
0291     long r = kernel_read(in_file, buf, len, &in_pos);
0292     if (r < 0)
0293         printk(KERN_ERR "RAMDISK: error while reading compressed data");
0294     else if (r == 0)
0295         printk(KERN_ERR "RAMDISK: EOF while reading compressed data");
0296     return r;
0297 }
0298
0299 static long __init compr_flush(void *window, unsigned long outcnt)
0300 {
0301     long written = kernel_write(out_file, window, outcnt, &out_pos);
0302     if (written != outcnt) {
0303         if (decompress_error == 0)
0304             printk(KERN_ERR
0305                    "RAMDISK: incomplete write (%ld != %ld)\n",
0306                    written, outcnt);
0307         decompress_error = 1;
0308         return -1;
0309     }
0310     return outcnt;
0311 }
0312
0313 static void __init error(char *x)
0314 {
0315     printk(KERN_ERR "%s\n", x);
0316     exit_code = 1;
0317     decompress_error = 1;
0318 }
0319
0320 static int __init crd_load(decompress_fn deco)
0321 {
0322     int result;
0323
0324     if (!deco) {
0325         pr_emerg("Invalid ramdisk decompression routine.  "
0326              "Select appropriate config option.\n");
0327         panic("Could not decompress initial ramdisk image.");
0328     }
0329
0330     result = deco(NULL, 0, compr_fill, compr_flush, NULL, NULL, error);
0331     if (decompress_error)
0332         result = 1;
0333     return result;
0334 }