libinstaller/fs.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 1998-2011 H. Peter Anvin - All Rights Reserved
   4  *   Copyright 2009-2011 Intel Corporation; author H. Peter Anvin
   5  *   Copyright 2011 Paulo Alcantara <pcacjr@gmail.com>
   6  *
   7  *   This program is free software; you can redistribute it and/or modify
   8  *   it under the terms of the GNU General Public License as published by
   9  *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
  10  *   Boston MA 02111-1307, USA; either version 2 of the License, or
  11  *   (at your option) any later version; incorporated herein by reference.
  12  *
  13  * ----------------------------------------------------------------------- */
  14
  15 /*
  16  * fs.c - Generic sanity check for FAT/NTFS-based installers
  17  */
  18
  19 #define _XOPEN_SOURCE 500       /* Required on glibc 2.x */
  20 #define _BSD_SOURCE
  21 /* glibc 2.20 deprecates _BSD_SOURCE in favour of _DEFAULT_SOURCE */
  22 #define _DEFAULT_SOURCE 1
  23 #include <stdio.h>
  24 #include <inttypes.h>
  25 #include <string.h>
  26 #include <stddef.h>
  27 #include <stdlib.h>
  28
  29 #include "syslinux.h"
  30 #include "syslxint.h"
  31 #include "syslxcom.h"
  32 #include "syslxfs.h"
  33
  34 void syslinux_make_bootsect(void *bs, int fs_type)
  35 {
  36     if (fs_type == VFAT) {
  37         struct fat_boot_sector *bootsect = bs;
  38         const struct fat_boot_sector *sbs =
  39             (const struct fat_boot_sector *)boot_sector;
  40
  41         memcpy(&bootsect->FAT_bsHead, &sbs->FAT_bsHead, FAT_bsHeadLen);
  42         memcpy(&bootsect->FAT_bsCode, &sbs->FAT_bsCode, FAT_bsCodeLen);
  43     } else if (fs_type == NTFS) {
  44         struct ntfs_boot_sector *bootsect = bs;
  45         const struct ntfs_boot_sector *sbs =
  46             (const struct ntfs_boot_sector *)boot_sector;
  47
  48         memcpy(&bootsect->NTFS_bsHead, &sbs->NTFS_bsHead, NTFS_bsHeadLen);
  49         memcpy(&bootsect->NTFS_bsCode, &sbs->NTFS_bsCode, NTFS_bsCodeLen);
  50     }
  51 }
  52
  53 static const char *check_fat_bootsect(const void *bs, int *fs_type)
  54 {
  55     int sectorsize;
  56     const struct fat_boot_sector *sectbuf = bs;
  57     long long sectors, fatsectors, dsectors;
  58     long long clusters;
  59     int rootdirents, clustersize;
  60
  61     sectorsize = get_16(&sectbuf->bsBytesPerSec);
  62
  63     clustersize = get_8(&sectbuf->bsSecPerClust);
  64     if (clustersize == 0 || (clustersize & (clustersize - 1)))
  65         return "impossible cluster size on an FAT volume";
  66
  67     sectors = get_16(&sectbuf->bsSectors);
  68     sectors = sectors ? sectors : get_32(&sectbuf->bsHugeSectors);
  69
  70     dsectors = sectors - get_16(&sectbuf->bsResSectors);
  71
  72     fatsectors = get_16(&sectbuf->bsFATsecs);
  73     fatsectors = fatsectors ? fatsectors : get_32(&sectbuf->bs32.FATSz32);
  74     fatsectors *= get_8(&sectbuf->bsFATs);
  75     dsectors -= fatsectors;
  76
  77     rootdirents = get_16(&sectbuf->bsRootDirEnts);
  78     dsectors -= (rootdirents + sectorsize / 32 - 1) / sectorsize;
  79
  80     if (dsectors < 0)
  81         return "negative number of data sectors on an FAT volume";
  82
  83     clusters = dsectors / clustersize;
  84
  85     fatsectors = get_16(&sectbuf->bsFATsecs);
  86     fatsectors = fatsectors ? fatsectors : get_32(&sectbuf->bs32.FATSz32);
  87     fatsectors *= get_8(&sectbuf->bsFATs);
  88
  89     if (!fatsectors)
  90         return "zero FAT sectors";
  91
  92     if (clusters < 0xFFF5) {
  93         /* FAT12 or FAT16 */
  94         if (!get_16(&sectbuf->bsFATsecs))
  95             return "zero FAT sectors (FAT12/16)";
  96
  97         if (get_8(&sectbuf->bs16.BootSignature) == 0x29) {
  98             if (!memcmp(&sectbuf->bs16.FileSysType, "FAT12   ", 8)) {
  99                 if (clusters >= 0xFF5)
 100                     return "more than 4084 clusters but claims FAT12";
 101             } else if (!memcmp(&sectbuf->bs16.FileSysType, "FAT16   ", 8)) {
 102                 if (clusters < 0xFF5)
 103                     return "less than 4084 clusters but claims FAT16";
 104             } else if (!memcmp(&sectbuf->bs16.FileSysType, "FAT32   ", 8)) {
 105                 return "less than 65525 clusters but claims FAT32";
 106             } else if (memcmp(&sectbuf->bs16.FileSysType, "FAT     ", 8)) {
 107                 static char fserr[] = "filesystem type \"????????\" not "
 108                     "supported";
 109                 memcpy(fserr + 17, &sectbuf->bs16.FileSysType, 8);
 110                 return fserr;
 111             }
 112         }
 113     } else if (clusters < 0x0FFFFFF5) {
 114         /*
 115          * FAT32...
 116          *
 117          * Moving the FileSysType and BootSignature was a lovely stroke
 118          * of M$ idiocy...
 119          */
 120         if (get_8(&sectbuf->bs32.BootSignature) != 0x29 ||
 121             memcmp(&sectbuf->bs32.FileSysType, "FAT32   ", 8))
 122             return "missing FAT32 signature";
 123     } else {
 124         return "impossibly large number of clusters on an FAT volume";
 125     }
 126
 127     if (fs_type)
 128         *fs_type = VFAT;
 129
 130     return NULL;
 131 }
 132
 133 static const char *check_ntfs_bootsect(const void *bs, int *fs_type)
 134 {
 135     const struct ntfs_boot_sector *sectbuf = bs;
 136
 137     if (memcmp(&sectbuf->bsOemName, "NTFS    ", 8) &&
 138         memcmp(&sectbuf->bsOemName, "MSWIN4.0", 8) &&
 139         memcmp(&sectbuf->bsOemName, "MSWIN4.1", 8))
 140         return "unknown OEM name but claims NTFS";
 141
 142     if (fs_type)
 143         *fs_type = NTFS;
 144
 145     return NULL;
 146 }
 147
 148 const char *syslinux_check_bootsect(const void *bs, int *fs_type)
 149 {
 150     uint8_t media_sig;
 151     int sectorsize;
 152     const struct fat_boot_sector *sectbuf = bs;
 153     const char *retval;
 154
 155     media_sig = get_8(&sectbuf->bsMedia);
 156     /* Must be 0xF0 or 0xF8-0xFF for FAT/NTFS volumes */
 157     if (media_sig != 0xF0 && media_sig < 0xF8)
 158         return "invalid media signature (not an FAT/NTFS volume?)";
 159
 160     sectorsize = get_16(&sectbuf->bsBytesPerSec);
 161     if (sectorsize == SECTOR_SIZE) ;    /* ok */
 162     else if (sectorsize >= 512 && sectorsize <= 4096 &&
 163              (sectorsize & (sectorsize - 1)) == 0)
 164         return "unsupported sectors size";
 165     else
 166         return "impossible sector size";
 167
 168     if (ntfs_check_zero_fields((struct ntfs_boot_sector *)bs))
 169         retval = check_ntfs_bootsect(bs, fs_type);
 170     else
 171         retval = check_fat_bootsect(bs, fs_type);
 172
 173     return retval;
 174 }