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0001 /*
0002  * misc.c
0003  *
0004  * PURPOSE
0005  *  Miscellaneous routines for the OSTA-UDF(tm) filesystem.
0006  *
0007  * COPYRIGHT
0008  *  This file is distributed under the terms of the GNU General Public
0009  *  License (GPL). Copies of the GPL can be obtained from:
0010  *      ftp://prep.ai.mit.edu/pub/gnu/GPL
0011  *  Each contributing author retains all rights to their own work.
0012  *
0013  *  (C) 1998 Dave Boynton
0014  *  (C) 1998-2004 Ben Fennema
0015  *  (C) 1999-2000 Stelias Computing Inc
0016  *
0017  * HISTORY
0018  *
0019  *  04/19/99 blf  partial support for reading/writing specific EA's
0020  */
0021 
0022 #include "udfdecl.h"
0023 
0024 #include <linux/fs.h>
0025 #include <linux/string.h>
0026 #include <linux/crc-itu-t.h>
0027 
0028 #include "udf_i.h"
0029 #include "udf_sb.h"
0030 
0031 struct buffer_head *udf_tgetblk(struct super_block *sb, udf_pblk_t block)
0032 {
0033     if (UDF_QUERY_FLAG(sb, UDF_FLAG_VARCONV))
0034         return sb_getblk(sb, udf_fixed_to_variable(block));
0035     else
0036         return sb_getblk(sb, block);
0037 }
0038 
0039 struct buffer_head *udf_tread(struct super_block *sb, udf_pblk_t block)
0040 {
0041     if (UDF_QUERY_FLAG(sb, UDF_FLAG_VARCONV))
0042         return sb_bread(sb, udf_fixed_to_variable(block));
0043     else
0044         return sb_bread(sb, block);
0045 }
0046 
0047 struct genericFormat *udf_add_extendedattr(struct inode *inode, uint32_t size,
0048                        uint32_t type, uint8_t loc)
0049 {
0050     uint8_t *ea = NULL, *ad = NULL;
0051     int offset;
0052     uint16_t crclen;
0053     struct udf_inode_info *iinfo = UDF_I(inode);
0054 
0055     ea = iinfo->i_data;
0056     if (iinfo->i_lenEAttr) {
0057         ad = iinfo->i_data + iinfo->i_lenEAttr;
0058     } else {
0059         ad = ea;
0060         size += sizeof(struct extendedAttrHeaderDesc);
0061     }
0062 
0063     offset = inode->i_sb->s_blocksize - udf_file_entry_alloc_offset(inode) -
0064         iinfo->i_lenAlloc;
0065 
0066     /* TODO - Check for FreeEASpace */
0067 
0068     if (loc & 0x01 && offset >= size) {
0069         struct extendedAttrHeaderDesc *eahd;
0070         eahd = (struct extendedAttrHeaderDesc *)ea;
0071 
0072         if (iinfo->i_lenAlloc)
0073             memmove(&ad[size], ad, iinfo->i_lenAlloc);
0074 
0075         if (iinfo->i_lenEAttr) {
0076             /* check checksum/crc */
0077             if (eahd->descTag.tagIdent !=
0078                     cpu_to_le16(TAG_IDENT_EAHD) ||
0079                 le32_to_cpu(eahd->descTag.tagLocation) !=
0080                     iinfo->i_location.logicalBlockNum)
0081                 return NULL;
0082         } else {
0083             struct udf_sb_info *sbi = UDF_SB(inode->i_sb);
0084 
0085             size -= sizeof(struct extendedAttrHeaderDesc);
0086             iinfo->i_lenEAttr +=
0087                 sizeof(struct extendedAttrHeaderDesc);
0088             eahd->descTag.tagIdent = cpu_to_le16(TAG_IDENT_EAHD);
0089             if (sbi->s_udfrev >= 0x0200)
0090                 eahd->descTag.descVersion = cpu_to_le16(3);
0091             else
0092                 eahd->descTag.descVersion = cpu_to_le16(2);
0093             eahd->descTag.tagSerialNum =
0094                     cpu_to_le16(sbi->s_serial_number);
0095             eahd->descTag.tagLocation = cpu_to_le32(
0096                     iinfo->i_location.logicalBlockNum);
0097             eahd->impAttrLocation = cpu_to_le32(0xFFFFFFFF);
0098             eahd->appAttrLocation = cpu_to_le32(0xFFFFFFFF);
0099         }
0100 
0101         offset = iinfo->i_lenEAttr;
0102         if (type < 2048) {
0103             if (le32_to_cpu(eahd->appAttrLocation) <
0104                     iinfo->i_lenEAttr) {
0105                 uint32_t aal =
0106                     le32_to_cpu(eahd->appAttrLocation);
0107                 memmove(&ea[offset - aal + size],
0108                     &ea[aal], offset - aal);
0109                 offset -= aal;
0110                 eahd->appAttrLocation =
0111                         cpu_to_le32(aal + size);
0112             }
0113             if (le32_to_cpu(eahd->impAttrLocation) <
0114                     iinfo->i_lenEAttr) {
0115                 uint32_t ial =
0116                     le32_to_cpu(eahd->impAttrLocation);
0117                 memmove(&ea[offset - ial + size],
0118                     &ea[ial], offset - ial);
0119                 offset -= ial;
0120                 eahd->impAttrLocation =
0121                         cpu_to_le32(ial + size);
0122             }
0123         } else if (type < 65536) {
0124             if (le32_to_cpu(eahd->appAttrLocation) <
0125                     iinfo->i_lenEAttr) {
0126                 uint32_t aal =
0127                     le32_to_cpu(eahd->appAttrLocation);
0128                 memmove(&ea[offset - aal + size],
0129                     &ea[aal], offset - aal);
0130                 offset -= aal;
0131                 eahd->appAttrLocation =
0132                         cpu_to_le32(aal + size);
0133             }
0134         }
0135         /* rewrite CRC + checksum of eahd */
0136         crclen = sizeof(struct extendedAttrHeaderDesc) - sizeof(struct tag);
0137         eahd->descTag.descCRCLength = cpu_to_le16(crclen);
0138         eahd->descTag.descCRC = cpu_to_le16(crc_itu_t(0, (char *)eahd +
0139                         sizeof(struct tag), crclen));
0140         eahd->descTag.tagChecksum = udf_tag_checksum(&eahd->descTag);
0141         iinfo->i_lenEAttr += size;
0142         return (struct genericFormat *)&ea[offset];
0143     }
0144 
0145     return NULL;
0146 }
0147 
0148 struct genericFormat *udf_get_extendedattr(struct inode *inode, uint32_t type,
0149                        uint8_t subtype)
0150 {
0151     struct genericFormat *gaf;
0152     uint8_t *ea = NULL;
0153     uint32_t offset;
0154     struct udf_inode_info *iinfo = UDF_I(inode);
0155 
0156     ea = iinfo->i_data;
0157 
0158     if (iinfo->i_lenEAttr) {
0159         struct extendedAttrHeaderDesc *eahd;
0160         eahd = (struct extendedAttrHeaderDesc *)ea;
0161 
0162         /* check checksum/crc */
0163         if (eahd->descTag.tagIdent !=
0164                 cpu_to_le16(TAG_IDENT_EAHD) ||
0165             le32_to_cpu(eahd->descTag.tagLocation) !=
0166                 iinfo->i_location.logicalBlockNum)
0167             return NULL;
0168 
0169         if (type < 2048)
0170             offset = sizeof(struct extendedAttrHeaderDesc);
0171         else if (type < 65536)
0172             offset = le32_to_cpu(eahd->impAttrLocation);
0173         else
0174             offset = le32_to_cpu(eahd->appAttrLocation);
0175 
0176         while (offset + sizeof(*gaf) < iinfo->i_lenEAttr) {
0177             uint32_t attrLength;
0178 
0179             gaf = (struct genericFormat *)&ea[offset];
0180             attrLength = le32_to_cpu(gaf->attrLength);
0181 
0182             /* Detect undersized elements and buffer overflows */
0183             if ((attrLength < sizeof(*gaf)) ||
0184                 (attrLength > (iinfo->i_lenEAttr - offset)))
0185                 break;
0186 
0187             if (le32_to_cpu(gaf->attrType) == type &&
0188                     gaf->attrSubtype == subtype)
0189                 return gaf;
0190             else
0191                 offset += attrLength;
0192         }
0193     }
0194 
0195     return NULL;
0196 }
0197 
0198 /*
0199  * udf_read_tagged
0200  *
0201  * PURPOSE
0202  *  Read the first block of a tagged descriptor.
0203  *
0204  * HISTORY
0205  *  July 1, 1997 - Andrew E. Mileski
0206  *  Written, tested, and released.
0207  */
0208 struct buffer_head *udf_read_tagged(struct super_block *sb, uint32_t block,
0209                     uint32_t location, uint16_t *ident)
0210 {
0211     struct tag *tag_p;
0212     struct buffer_head *bh = NULL;
0213     u8 checksum;
0214 
0215     /* Read the block */
0216     if (block == 0xFFFFFFFF)
0217         return NULL;
0218 
0219     bh = udf_tread(sb, block);
0220     if (!bh) {
0221         udf_err(sb, "read failed, block=%u, location=%u\n",
0222             block, location);
0223         return NULL;
0224     }
0225 
0226     tag_p = (struct tag *)(bh->b_data);
0227 
0228     *ident = le16_to_cpu(tag_p->tagIdent);
0229 
0230     if (location != le32_to_cpu(tag_p->tagLocation)) {
0231         udf_debug("location mismatch block %u, tag %u != %u\n",
0232               block, le32_to_cpu(tag_p->tagLocation), location);
0233         goto error_out;
0234     }
0235 
0236     /* Verify the tag checksum */
0237     checksum = udf_tag_checksum(tag_p);
0238     if (checksum != tag_p->tagChecksum) {
0239         udf_err(sb, "tag checksum failed, block %u: 0x%02x != 0x%02x\n",
0240             block, checksum, tag_p->tagChecksum);
0241         goto error_out;
0242     }
0243 
0244     /* Verify the tag version */
0245     if (tag_p->descVersion != cpu_to_le16(0x0002U) &&
0246         tag_p->descVersion != cpu_to_le16(0x0003U)) {
0247         udf_err(sb, "tag version 0x%04x != 0x0002 || 0x0003, block %u\n",
0248             le16_to_cpu(tag_p->descVersion), block);
0249         goto error_out;
0250     }
0251 
0252     /* Verify the descriptor CRC */
0253     if (le16_to_cpu(tag_p->descCRCLength) + sizeof(struct tag) > sb->s_blocksize ||
0254         le16_to_cpu(tag_p->descCRC) == crc_itu_t(0,
0255                     bh->b_data + sizeof(struct tag),
0256                     le16_to_cpu(tag_p->descCRCLength)))
0257         return bh;
0258 
0259     udf_debug("Crc failure block %u: crc = %u, crclen = %u\n", block,
0260           le16_to_cpu(tag_p->descCRC),
0261           le16_to_cpu(tag_p->descCRCLength));
0262 error_out:
0263     brelse(bh);
0264     return NULL;
0265 }
0266 
0267 struct buffer_head *udf_read_ptagged(struct super_block *sb,
0268                      struct kernel_lb_addr *loc,
0269                      uint32_t offset, uint16_t *ident)
0270 {
0271     return udf_read_tagged(sb, udf_get_lb_pblock(sb, loc, offset),
0272                    loc->logicalBlockNum + offset, ident);
0273 }
0274 
0275 void udf_update_tag(char *data, int length)
0276 {
0277     struct tag *tptr = (struct tag *)data;
0278     length -= sizeof(struct tag);
0279 
0280     tptr->descCRCLength = cpu_to_le16(length);
0281     tptr->descCRC = cpu_to_le16(crc_itu_t(0, data + sizeof(struct tag), length));
0282     tptr->tagChecksum = udf_tag_checksum(tptr);
0283 }
0284 
0285 void udf_new_tag(char *data, uint16_t ident, uint16_t version, uint16_t snum,
0286          uint32_t loc, int length)
0287 {
0288     struct tag *tptr = (struct tag *)data;
0289     tptr->tagIdent = cpu_to_le16(ident);
0290     tptr->descVersion = cpu_to_le16(version);
0291     tptr->tagSerialNum = cpu_to_le16(snum);
0292     tptr->tagLocation = cpu_to_le32(loc);
0293     udf_update_tag(data, length);
0294 }
0295 
0296 u8 udf_tag_checksum(const struct tag *t)
0297 {
0298     u8 *data = (u8 *)t;
0299     u8 checksum = 0;
0300     int i;
0301     for (i = 0; i < sizeof(struct tag); ++i)
0302         if (i != 4) /* position of checksum */
0303             checksum += data[i];
0304     return checksum;
0305 }
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