fs/isofs/rock.c

   1 /*
   2  *  linux/fs/isofs/rock.c
   3  *
   4  *  (C) 1992, 1993  Eric Youngdale
   5  *
   6  *  Rock Ridge Extensions to iso9660
   7  */
   8
   9 #include <linux/slab.h>
  10 #include <linux/pagemap.h>
  11 #include <linux/smp_lock.h>
  12
  13 #include "isofs.h"
  14 #include "rock.h"
  15
  16 /* These functions are designed to read the system areas of a directory record
  17  * and extract relevant information.  There are different functions provided
  18  * depending upon what information we need at the time.  One function fills
  19  * out an inode structure, a second one extracts a filename, a third one
  20  * returns a symbolic link name, and a fourth one returns the extent number
  21  * for the file. */
  22
  23 #define SIG(A,B) ((A) | ((B) << 8))     /* isonum_721() */
  24
  25 /*
  26  * This is a way of ensuring that we have something in the system
  27  *  use fields that is compatible with Rock Ridge.  Return zero on success.
  28  */
  29
  30 static int check_sp(struct rock_ridge *rr, struct inode *inode)
  31 {
  32         if (rr->u.SP.magic[0] != 0xbe)
  33                 return -1;
  34         if (rr->u.SP.magic[1] != 0xef)
  35                 return -1;
  36         ISOFS_SB(inode->i_sb)->s_rock_offset = rr->u.SP.skip;
  37         return 0;
  38 }
  39
  40 #define SETUP_ROCK_RIDGE(DE,CHR,LEN)                            \
  41   {LEN= sizeof(struct iso_directory_record) + DE->name_len[0];  \
  42   if(LEN & 1) LEN++;                                            \
  43   CHR = ((unsigned char *) DE) + LEN;                           \
  44   LEN = *((unsigned char *) DE) - LEN;                          \
  45   if (LEN<0) LEN=0;                                             \
  46   if (ISOFS_SB(inode->i_sb)->s_rock_offset!=-1)                \
  47   {                                                             \
  48      LEN-=ISOFS_SB(inode->i_sb)->s_rock_offset;                \
  49      CHR+=ISOFS_SB(inode->i_sb)->s_rock_offset;                \
  50      if (LEN<0) LEN=0;                                          \
  51   }                                                             \
  52 }
  53
  54 #define MAYBE_CONTINUE(LABEL,DEV) \
  55   {if (buffer) { kfree(buffer); buffer = NULL; } \
  56   if (cont_extent){ \
  57     int block, offset, offset1; \
  58     struct buffer_head * pbh; \
  59     buffer = kmalloc(cont_size,GFP_KERNEL); \
  60     if (!buffer) goto out; \
  61     block = cont_extent; \
  62     offset = cont_offset; \
  63     offset1 = 0; \
  64     pbh = sb_bread(DEV->i_sb, block); \
  65     if(pbh){       \
  66       if (offset > pbh->b_size || offset + cont_size > pbh->b_size){    \
  67         brelse(pbh); \
  68         goto out; \
  69       } \
  70       memcpy(buffer + offset1, pbh->b_data + offset, cont_size - offset1); \
  71       brelse(pbh); \
  72       chr = (unsigned char *) buffer; \
  73       len = cont_size; \
  74       cont_extent = 0; \
  75       cont_size = 0; \
  76       cont_offset = 0; \
  77       goto LABEL; \
  78     }    \
  79     printk("Unable to read rock-ridge attributes\n");    \
  80   }}
  81
  82 /* return length of name field; 0: not found, -1: to be ignored */
  83 int get_rock_ridge_filename(struct iso_directory_record *de,
  84                             char *retname, struct inode *inode)
  85 {
  86         int len;
  87         unsigned char *chr;
  88         int cont_extent = 0;
  89         int cont_offset = 0;
  90         int cont_size = 0;
  91         void *buffer = NULL;
  92         struct rock_ridge *rr;
  93         int sig;
  94         int retnamlen = 0;
  95         int truncate = 0;
  96
  97         if (!ISOFS_SB(inode->i_sb)->s_rock)
  98                 return 0;
  99         *retname = 0;
 100
 101         SETUP_ROCK_RIDGE(de, chr, len);
 102 repeat:
 103
 104         while (len > 2) { /* There may be one byte for padding somewhere */
 105                 rr = (struct rock_ridge *)chr;
 106                 if (rr->len < 3)
 107                         goto out;       /* Something got screwed up here */
 108                 sig = isonum_721(chr);
 109                 chr += rr->len;
 110                 len -= rr->len;
 111                 if (len < 0)
 112                         goto out;       /* corrupted isofs */
 113
 114                 switch (sig) {
 115                 case SIG('R', 'R'):
 116                         if ((rr->u.RR.flags[0] & RR_NM) == 0)
 117                                 goto out;
 118                         break;
 119                 case SIG('S', 'P'):
 120                         if (check_sp(rr, inode))
 121                                 goto out;
 122                         break;
 123                 case SIG('C', 'E'):
 124                         cont_extent = isonum_733(rr->u.CE.extent);
 125                         cont_offset = isonum_733(rr->u.CE.offset);
 126                         cont_size = isonum_733(rr->u.CE.size);
 127                         break;
 128                 case SIG('N', 'M'):
 129                         if (truncate)
 130                                 break;
 131                         if (rr->len < 5)
 132                                 break;
 133                         /*
 134                          * If the flags are 2 or 4, this indicates '.' or '..'.
 135                          * We don't want to do anything with this, because it
 136                          * screws up the code that calls us.  We don't really
 137                          * care anyways, since we can just use the non-RR
 138                          * name.
 139                          */
 140                         if (rr->u.NM.flags & 6)
 141                                 break;
 142
 143                         if (rr->u.NM.flags & ~1) {
 144                                 printk("Unsupported NM flag settings (%d)\n",
 145                                         rr->u.NM.flags);
 146                                 break;
 147                         }
 148                         if ((strlen(retname) + rr->len - 5) >= 254) {
 149                                 truncate = 1;
 150                                 break;
 151                         }
 152                         strncat(retname, rr->u.NM.name, rr->len - 5);
 153                         retnamlen += rr->len - 5;
 154                         break;
 155                 case SIG('R', 'E'):
 156                         if (buffer)
 157                                 kfree(buffer);
 158                         return -1;
 159                 default:
 160                         break;
 161                 }
 162         }
 163         MAYBE_CONTINUE(repeat, inode);
 164         kfree(buffer);
 165         return retnamlen;       /* If 0, this file did not have a NM field */
 166 out:
 167         if (buffer)
 168                 kfree(buffer);
 169         return 0;
 170 }
 171
 172 static int
 173 parse_rock_ridge_inode_internal(struct iso_directory_record *de,
 174                                 struct inode *inode, int regard_xa)
 175 {
 176         int len;
 177         unsigned char *chr;
 178         int symlink_len = 0;
 179         int cnt, sig;
 180         struct inode *reloc;
 181         struct rock_ridge *rr;
 182         int rootflag;
 183         int cont_extent = 0;
 184         int cont_offset = 0;
 185         int cont_size = 0;
 186         void *buffer = NULL;
 187
 188         if (!ISOFS_SB(inode->i_sb)->s_rock)
 189                 return 0;
 190
 191         SETUP_ROCK_RIDGE(de, chr, len);
 192         if (regard_xa) {
 193                 chr += 14;
 194                 len -= 14;
 195                 if (len < 0)
 196                         len = 0;
 197         }
 198
 199 repeat:
 200         while (len > 2) { /* There may be one byte for padding somewhere */
 201                 rr = (struct rock_ridge *)chr;
 202                 if (rr->len < 3)
 203                         goto out;       /* Something got screwed up here */
 204                 sig = isonum_721(chr);
 205                 chr += rr->len;
 206                 len -= rr->len;
 207                 if (len < 0)
 208                         goto out;       /* corrupted isofs */
 209
 210                 switch (sig) {
 211 #ifndef CONFIG_ZISOFS           /* No flag for SF or ZF */
 212                 case SIG('R', 'R'):
 213                         if ((rr->u.RR.flags[0] &
 214                              (RR_PX | RR_TF | RR_SL | RR_CL)) == 0)
 215                                 goto out;
 216                         break;
 217 #endif
 218                 case SIG('S', 'P'):
 219                         if (check_sp(rr, inode))
 220                                 goto out;
 221                         break;
 222                 case SIG('C', 'E'):
 223                         cont_extent = isonum_733(rr->u.CE.extent);
 224                         cont_offset = isonum_733(rr->u.CE.offset);
 225                         cont_size = isonum_733(rr->u.CE.size);
 226                         break;
 227                 case SIG('E', 'R'):
 228                         ISOFS_SB(inode->i_sb)->s_rock = 1;
 229                         printk(KERN_DEBUG "ISO 9660 Extensions: ");
 230                         {
 231                                 int p;
 232                                 for (p = 0; p < rr->u.ER.len_id; p++)
 233                                         printk("%c", rr->u.ER.data[p]);
 234                         }
 235                         printk("\n");
 236                         break;
 237                 case SIG('P', 'X'):
 238                         inode->i_mode = isonum_733(rr->u.PX.mode);
 239                         inode->i_nlink = isonum_733(rr->u.PX.n_links);
 240                         inode->i_uid = isonum_733(rr->u.PX.uid);
 241                         inode->i_gid = isonum_733(rr->u.PX.gid);
 242                         break;
 243                 case SIG('P', 'N'):
 244                         {
 245                                 int high, low;
 246                                 high = isonum_733(rr->u.PN.dev_high);
 247                                 low = isonum_733(rr->u.PN.dev_low);
 248                                 /*
 249                                  * The Rock Ridge standard specifies that if
 250                                  * sizeof(dev_t) <= 4, then the high field is
 251                                  * unused, and the device number is completely
 252                                  * stored in the low field.  Some writers may
 253                                  * ignore this subtlety,
 254                                  * and as a result we test to see if the entire
 255                                  * device number is
 256                                  * stored in the low field, and use that.
 257                                  */
 258                                 if ((low & ~0xff) && high == 0) {
 259                                         inode->i_rdev =
 260                                             MKDEV(low >> 8, low & 0xff);
 261                                 } else {
 262                                         inode->i_rdev =
 263                                             MKDEV(high, low);
 264                                 }
 265                         }
 266                         break;
 267                 case SIG('T', 'F'):
 268                         /*
 269                          * Some RRIP writers incorrectly place ctime in the
 270                          * TF_CREATE field. Try to handle this correctly for
 271                          * either case.
 272                          */
 273                         /* Rock ridge never appears on a High Sierra disk */
 274                         cnt = 0;
 275                         if (rr->u.TF.flags & TF_CREATE) {
 276                                 inode->i_ctime.tv_sec =
 277                                     iso_date(rr->u.TF.times[cnt++].time,
 278                                              0);
 279                                 inode->i_ctime.tv_nsec = 0;
 280                         }
 281                         if (rr->u.TF.flags & TF_MODIFY) {
 282                                 inode->i_mtime.tv_sec =
 283                                     iso_date(rr->u.TF.times[cnt++].time,
 284                                              0);
 285                                 inode->i_mtime.tv_nsec = 0;
 286                         }
 287                         if (rr->u.TF.flags & TF_ACCESS) {
 288                                 inode->i_atime.tv_sec =
 289                                     iso_date(rr->u.TF.times[cnt++].time,
 290                                              0);
 291                                 inode->i_atime.tv_nsec = 0;
 292                         }
 293                         if (rr->u.TF.flags & TF_ATTRIBUTES) {
 294                                 inode->i_ctime.tv_sec =
 295                                     iso_date(rr->u.TF.times[cnt++].time,
 296                                              0);
 297                                 inode->i_ctime.tv_nsec = 0;
 298                         }
 299                         break;
 300                 case SIG('S', 'L'):
 301                         {
 302                                 int slen;
 303                                 struct SL_component *slp;
 304                                 struct SL_component *oldslp;
 305                                 slen = rr->len - 5;
 306                                 slp = &rr->u.SL.link;
 307                                 inode->i_size = symlink_len;
 308                                 while (slen > 1) {
 309                                         rootflag = 0;
 310                                         switch (slp->flags & ~1) {
 311                                         case 0:
 312                                                 inode->i_size +=
 313                                                     slp->len;
 314                                                 break;
 315                                         case 2:
 316                                                 inode->i_size += 1;
 317                                                 break;
 318                                         case 4:
 319                                                 inode->i_size += 2;
 320                                                 break;
 321                                         case 8:
 322                                                 rootflag = 1;
 323                                                 inode->i_size += 1;
 324                                                 break;
 325                                         default:
 326                                                 printk("Symlink component flag "
 327                                                         "not implemented\n");
 328                                         }
 329                                         slen -= slp->len + 2;
 330                                         oldslp = slp;
 331                                         slp = (struct SL_component *)
 332                                                 (((char *)slp) + slp->len + 2);
 333
 334                                         if (slen < 2) {
 335                                                 if (((rr->u.SL.
 336                                                       flags & 1) != 0)
 337                                                     &&
 338                                                     ((oldslp->
 339                                                       flags & 1) == 0))
 340                                                         inode->i_size +=
 341                                                             1;
 342                                                 break;
 343                                         }
 344
 345                                         /*
 346                                          * If this component record isn't
 347                                          * continued, then append a '/'.
 348                                          */
 349                                         if (!rootflag
 350                                             && (oldslp->flags & 1) == 0)
 351                                                 inode->i_size += 1;
 352                                 }
 353                         }
 354                         symlink_len = inode->i_size;
 355                         break;
 356                 case SIG('R', 'E'):
 357                         printk(KERN_WARNING "Attempt to read inode for "
 358                                         "relocated directory\n");
 359                         goto out;
 360                 case SIG('C', 'L'):
 361                         ISOFS_I(inode)->i_first_extent =
 362                             isonum_733(rr->u.CL.location);
 363                         reloc =
 364                             isofs_iget(inode->i_sb,
 365                                        ISOFS_I(inode)->i_first_extent,
 366                                        0);
 367                         if (!reloc)
 368                                 goto out;
 369                         inode->i_mode = reloc->i_mode;
 370                         inode->i_nlink = reloc->i_nlink;
 371                         inode->i_uid = reloc->i_uid;
 372                         inode->i_gid = reloc->i_gid;
 373                         inode->i_rdev = reloc->i_rdev;
 374                         inode->i_size = reloc->i_size;
 375                         inode->i_blocks = reloc->i_blocks;
 376                         inode->i_atime = reloc->i_atime;
 377                         inode->i_ctime = reloc->i_ctime;
 378                         inode->i_mtime = reloc->i_mtime;
 379                         iput(reloc);
 380                         break;
 381 #ifdef CONFIG_ZISOFS
 382                 case SIG('Z', 'F'): {
 383                         int algo;
 384
 385                         if (ISOFS_SB(inode->i_sb)->s_nocompress)
 386                                 break;
 387                         algo = isonum_721(rr->u.ZF.algorithm);
 388                         if (algo == SIG('p', 'z')) {
 389                                 int block_shift =
 390                                         isonum_711(&rr->u.ZF.parms[1]);
 391                                 if (block_shift < PAGE_CACHE_SHIFT
 392                                                 || block_shift > 17) {
 393                                         printk(KERN_WARNING "isofs: "
 394                                                 "Can't handle ZF block "
 395                                                 "size of 2^%d\n",
 396                                                 block_shift);
 397                                 } else {
 398                                         /*
 399                                          * Note: we don't change
 400                                          * i_blocks here
 401                                          */
 402                                         ISOFS_I(inode)->i_file_format =
 403                                                 isofs_file_compressed;
 404                                         /*
 405                                          * Parameters to compression
 406                                          * algorithm (header size,
 407                                          * block size)
 408                                          */
 409                                         ISOFS_I(inode)->i_format_parm[0] =
 410                                                 isonum_711(&rr->u.ZF.parms[0]);
 411                                         ISOFS_I(inode)->i_format_parm[1] =
 412                                                 isonum_711(&rr->u.ZF.parms[1]);
 413                                         inode->i_size =
 414                                             isonum_733(rr->u.ZF.
 415                                                        real_size);
 416                                 }
 417                         } else {
 418                                 printk(KERN_WARNING
 419                                        "isofs: Unknown ZF compression "
 420                                                 "algorithm: %c%c\n",
 421                                        rr->u.ZF.algorithm[0],
 422                                        rr->u.ZF.algorithm[1]);
 423                         }
 424                         break;
 425                 }
 426 #endif
 427                 default:
 428                         break;
 429                 }
 430         }
 431         MAYBE_CONTINUE(repeat, inode);
 432 out:
 433         if (buffer)
 434                 kfree(buffer);
 435         return 0;
 436 }
 437
 438 static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
 439 {
 440         int slen;
 441         int rootflag;
 442         struct SL_component *oldslp;
 443         struct SL_component *slp;
 444         slen = rr->len - 5;
 445         slp = &rr->u.SL.link;
 446         while (slen > 1) {
 447                 rootflag = 0;
 448                 switch (slp->flags & ~1) {
 449                 case 0:
 450                         if (slp->len > plimit - rpnt)
 451                                 return NULL;
 452                         memcpy(rpnt, slp->text, slp->len);
 453                         rpnt += slp->len;
 454                         break;
 455                 case 2:
 456                         if (rpnt >= plimit)
 457                                 return NULL;
 458                         *rpnt++ = '.';
 459                         break;
 460                 case 4:
 461                         if (2 > plimit - rpnt)
 462                                 return NULL;
 463                         *rpnt++ = '.';
 464                         *rpnt++ = '.';
 465                         break;
 466                 case 8:
 467                         if (rpnt >= plimit)
 468                                 return NULL;
 469                         rootflag = 1;
 470                         *rpnt++ = '/';
 471                         break;
 472                 default:
 473                         printk("Symlink component flag not implemented (%d)\n",
 474                                slp->flags);
 475                 }
 476                 slen -= slp->len + 2;
 477                 oldslp = slp;
 478                 slp = (struct SL_component *)((char *)slp + slp->len + 2);
 479
 480                 if (slen < 2) {
 481                         /*
 482                          * If there is another SL record, and this component
 483                          * record isn't continued, then add a slash.
 484                          */
 485                         if ((!rootflag) && (rr->u.SL.flags & 1) &&
 486                             !(oldslp->flags & 1)) {
 487                                 if (rpnt >= plimit)
 488                                         return NULL;
 489                                 *rpnt++ = '/';
 490                         }
 491                         break;
 492                 }
 493
 494                 /*
 495                  * If this component record isn't continued, then append a '/'.
 496                  */
 497                 if (!rootflag && !(oldslp->flags & 1)) {
 498                         if (rpnt >= plimit)
 499                                 return NULL;
 500                         *rpnt++ = '/';
 501                 }
 502         }
 503         return rpnt;
 504 }
 505
 506 int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode)
 507 {
 508         int result = parse_rock_ridge_inode_internal(de, inode, 0);
 509         /* if rockridge flag was reset and we didn't look for attributes
 510          * behind eventual XA attributes, have a look there */
 511         if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
 512             && (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
 513                 result = parse_rock_ridge_inode_internal(de, inode, 14);
 514         }
 515         return result;
 516 }
 517
 518 /* readpage() for symlinks: reads symlink contents into the page and either
 519    makes it uptodate and returns 0 or returns error (-EIO) */
 520
 521 static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
 522 {
 523         struct inode *inode = page->mapping->host;
 524         struct iso_inode_info *ei = ISOFS_I(inode);
 525         char *link = kmap(page);
 526         unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
 527         struct buffer_head *bh;
 528         char *rpnt = link;
 529         unsigned char *pnt;
 530         struct iso_directory_record *raw_inode;
 531         int cont_extent = 0;
 532         int cont_offset = 0;
 533         int cont_size = 0;
 534         void *buffer = NULL;
 535         unsigned long block, offset;
 536         int sig;
 537         int len;
 538         unsigned char *chr;
 539         struct rock_ridge *rr;
 540
 541         if (!ISOFS_SB(inode->i_sb)->s_rock)
 542                 goto error;
 543
 544         block = ei->i_iget5_block;
 545         lock_kernel();
 546         bh = sb_bread(inode->i_sb, block);
 547         if (!bh)
 548                 goto out_noread;
 549
 550         offset = ei->i_iget5_offset;
 551         pnt = (unsigned char *)bh->b_data + offset;
 552
 553         raw_inode = (struct iso_directory_record *)pnt;
 554
 555         /*
 556          * If we go past the end of the buffer, there is some sort of error.
 557          */
 558         if (offset + *pnt > bufsize)
 559                 goto out_bad_span;
 560
 561         /* Now test for possible Rock Ridge extensions which will override
 562            some of these numbers in the inode structure. */
 563
 564         SETUP_ROCK_RIDGE(raw_inode, chr, len);
 565
 566 repeat:
 567         while (len > 2) { /* There may be one byte for padding somewhere */
 568                 rr = (struct rock_ridge *)chr;
 569                 if (rr->len < 3)
 570                         goto out;       /* Something got screwed up here */
 571                 sig = isonum_721(chr);
 572                 chr += rr->len;
 573                 len -= rr->len;
 574                 if (len < 0)
 575                         goto out;       /* corrupted isofs */
 576
 577                 switch (sig) {
 578                 case SIG('R', 'R'):
 579                         if ((rr->u.RR.flags[0] & RR_SL) == 0)
 580                                 goto out;
 581                         break;
 582                 case SIG('S', 'P'):
 583                         if (check_sp(rr, inode))
 584                                 goto out;
 585                         break;
 586                 case SIG('S', 'L'):
 587                         rpnt = get_symlink_chunk(rpnt, rr,
 588                                                  link + (PAGE_SIZE - 1));
 589                         if (rpnt == NULL)
 590                                 goto out;
 591                         break;
 592                 case SIG('C', 'E'):
 593                         /* This tells is if there is a continuation record */
 594                         cont_extent = isonum_733(rr->u.CE.extent);
 595                         cont_offset = isonum_733(rr->u.CE.offset);
 596                         cont_size = isonum_733(rr->u.CE.size);
 597                 default:
 598                         break;
 599                 }
 600         }
 601         MAYBE_CONTINUE(repeat, inode);
 602         kfree(buffer);
 603
 604         if (rpnt == link)
 605                 goto fail;
 606         brelse(bh);
 607         *rpnt = '\0';
 608         unlock_kernel();
 609         SetPageUptodate(page);
 610         kunmap(page);
 611         unlock_page(page);
 612         return 0;
 613
 614         /* error exit from macro */
 615 out:
 616         if (buffer)
 617                 kfree(buffer);
 618         goto fail;
 619 out_noread:
 620         printk("unable to read i-node block");
 621         goto fail;
 622 out_bad_span:
 623         printk("symlink spans iso9660 blocks\n");
 624 fail:
 625         brelse(bh);
 626         unlock_kernel();
 627 error:
 628         SetPageError(page);
 629         kunmap(page);
 630         unlock_page(page);
 631         return -EIO;
 632 }
 633
 634 struct address_space_operations isofs_symlink_aops = {
 635         .readpage = rock_ridge_symlink_readpage
 636 };