ext2_csum.c

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    1 /*-
    2  * Copyright (c) 2017, Fedor Uporov
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  *
   26  * $FreeBSD: releng/11.2/sys/fs/ext2fs/ext2_csum.c 322712 2017-08-20 01:27:33Z pfg $
   27  */
   28 
   29 #include <sys/param.h>
   30 #include <sys/systm.h>
   31 #include <sys/types.h>
   32 #include <sys/stat.h>
   33 #include <sys/kernel.h>
   34 #include <sys/malloc.h>
   35 #include <sys/vnode.h>
   36 #include <sys/bio.h>
   37 #include <sys/buf.h>
   38 #include <sys/endian.h>
   39 #include <sys/conf.h>
   40 #include <sys/mount.h>
   41 
   42 #include <fs/ext2fs/fs.h>
   43 #include <fs/ext2fs/ext2fs.h>
   44 #include <fs/ext2fs/inode.h>
   45 #include <fs/ext2fs/ext2_extern.h>
   46 
   47 static uint16_t
   48 ext2_crc16(uint16_t crc, const void *buffer, unsigned int len)
   49 {
   50         const unsigned char *cp = buffer;
   51         /* CRC table for the CRC-16. The poly is 0x8005 (x16 + x15 + x2 + 1). */
   52         static uint16_t const crc16_table[256] = {
   53                 0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
   54                 0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
   55                 0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
   56                 0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
   57                 0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
   58                 0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
   59                 0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
   60                 0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
   61                 0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
   62                 0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
   63                 0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
   64                 0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
   65                 0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
   66                 0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
   67                 0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
   68                 0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
   69                 0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
   70                 0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
   71                 0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
   72                 0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
   73                 0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
   74                 0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
   75                 0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
   76                 0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
   77                 0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
   78                 0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
   79                 0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
   80                 0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
   81                 0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
   82                 0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
   83                 0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
   84                 0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040
   85         };
   86 
   87         while (len--)
   88                 crc = (((crc >> 8) & 0xffU) ^
   89                     crc16_table[(crc ^ *cp++) & 0xffU]) & 0x0000ffffU;
   90         return crc;
   91 }
   92 
   93 static uint16_t
   94 ext2_gd_csum(struct m_ext2fs *fs, uint32_t block_group, struct ext2_gd *gd)
   95 {
   96         size_t offset;
   97         uint16_t crc;
   98 
   99         offset = offsetof(struct ext2_gd, ext4bgd_csum);
  100 
  101         if (EXT2_HAS_RO_COMPAT_FEATURE(fs, EXT2F_ROCOMPAT_GDT_CSUM)) {
  102                 crc = ext2_crc16(~0, fs->e2fs->e2fs_uuid,
  103                     sizeof(fs->e2fs->e2fs_uuid));
  104                 crc = ext2_crc16(crc, (uint8_t *)&block_group,
  105                     sizeof(block_group));
  106                 crc = ext2_crc16(crc, (uint8_t *)gd, offset);
  107                 offset += sizeof(gd->ext4bgd_csum); /* skip checksum */
  108                 if (EXT2_HAS_INCOMPAT_FEATURE(fs, EXT2F_INCOMPAT_64BIT) &&
  109                     offset < fs->e2fs->e3fs_desc_size)
  110                         crc = ext2_crc16(crc, (uint8_t *)gd + offset,
  111                                          fs->e2fs->e3fs_desc_size - offset);
  112                 return (crc);
  113         }
  114 
  115         return (0);
  116 }
  117 
  118 int
  119 ext2_gd_csum_verify(struct m_ext2fs *fs, struct cdev *dev)
  120 {
  121         unsigned int i;
  122         int error = 0;
  123 
  124         for (i = 0; i < fs->e2fs_gcount; i++) {
  125                 if (fs->e2fs_gd[i].ext4bgd_csum !=
  126                     ext2_gd_csum(fs, i, &fs->e2fs_gd[i])) {
  127                         printf(
  128 "WARNING: mount of %s denied due bad gd=%d csum=0x%x, expected=0x%x - run fsck\n",
  129                             devtoname(dev), i, fs->e2fs_gd[i].ext4bgd_csum,
  130                             ext2_gd_csum(fs, i, &fs->e2fs_gd[i]));
  131                         error = EINVAL;
  132                         break;
  133                 }
  134         }
  135 
  136         return (error);
  137 }
  138 
  139 void
  140 ext2_gd_csum_set(struct m_ext2fs *fs)
  141 {
  142         unsigned int i;
  143 
  144         for (i = 0; i < fs->e2fs_gcount; i++)
  145                     fs->e2fs_gd[i].ext4bgd_csum = 
  146                         ext2_gd_csum(fs, i, &fs->e2fs_gd[i]);
  147 }

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FreeBSD/Linux Kernel Cross Reference sys/fs/ext2fs/ext2_csum.c

FreeBSD/Linux Kernel Cross Reference
sys/fs/ext2fs/ext2_csum.c