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 /*
  17  * These functions are designed to read the system areas of a directory record
  18  * and extract relevant information.  There are different functions provided
  19  * depending upon what information we need at the time.  One function fills
  20  * out an inode structure, a second one extracts a filename, a third one
  21  * returns a symbolic link name, and a fourth one returns the extent number
  22  * for the file.
  23  */
  24
  25 #define SIG(A,B) ((A) | ((B) << 8))     /* isonum_721() */
  26
  27 struct rock_state {
  28         void *buffer;
  29         unsigned char *chr;
  30         int len;
  31         int cont_size;
  32         int cont_extent;
  33         int cont_offset;
  34         struct inode *inode;
  35 };
  36
  37 /*
  38  * This is a way of ensuring that we have something in the system
  39  * use fields that is compatible with Rock Ridge.  Return zero on success.
  40  */
  41
  42 static int check_sp(struct rock_ridge *rr, struct inode *inode)
  43 {
  44         if (rr->u.SP.magic[0] != 0xbe)
  45                 return -1;
  46         if (rr->u.SP.magic[1] != 0xef)
  47                 return -1;
  48         ISOFS_SB(inode->i_sb)->s_rock_offset = rr->u.SP.skip;
  49         return 0;
  50 }
  51
  52 static void setup_rock_ridge(struct iso_directory_record *de,
  53                         struct inode *inode, struct rock_state *rs)
  54 {
  55         rs->len = sizeof(struct iso_directory_record) + de->name_len[0];
  56         if (rs->len & 1)
  57                 (rs->len)++;
  58         rs->chr = (unsigned char *)de + rs->len;
  59         rs->len = *((unsigned char *)de) - rs->len;
  60         if (rs->len < 0)
  61                 rs->len = 0;
  62
  63         if (ISOFS_SB(inode->i_sb)->s_rock_offset != -1) {
  64                 rs->len -= ISOFS_SB(inode->i_sb)->s_rock_offset;
  65                 rs->chr += ISOFS_SB(inode->i_sb)->s_rock_offset;
  66                 if (rs->len < 0)
  67                         rs->len = 0;
  68         }
  69 }
  70
  71 static void init_rock_state(struct rock_state *rs, struct inode *inode)
  72 {
  73         memset(rs, 0, sizeof(*rs));
  74         rs->inode = inode;
  75 }
  76
  77 /*
  78  * Returns 0 if the caller should continue scanning, 1 if the scan must end
  79  * and -ve on error.
  80  */
  81 static int rock_continue(struct rock_state *rs)
  82 {
  83         int ret = 1;
  84
  85         kfree(rs->buffer);
  86         rs->buffer = NULL;
  87         if (rs->cont_extent) {
  88                 struct buffer_head *bh;
  89
  90                 rs->buffer = kmalloc(rs->cont_size, GFP_KERNEL);
  91                 if (!rs->buffer) {
  92                         ret = -ENOMEM;
  93                         goto out;
  94                 }
  95                 ret = -EIO;
  96                 bh = sb_bread(rs->inode->i_sb, rs->cont_extent);
  97                 if (bh) {
  98                         memcpy(rs->buffer, bh->b_data + rs->cont_offset,
  99                                         rs->cont_size);
 100                         put_bh(bh);
 101                         rs->chr = rs->buffer;
 102                         rs->len = rs->cont_size;
 103                         rs->cont_extent = 0;
 104                         rs->cont_size = 0;
 105                         rs->cont_offset = 0;
 106                         return 0;
 107                 }
 108                 printk("Unable to read rock-ridge attributes\n");
 109         }
 110 out:
 111         kfree(rs->buffer);
 112         rs->buffer = NULL;
 113         return ret;
 114 }
 115
 116 /*
 117  * return length of name field; 0: not found, -1: to be ignored
 118  */
 119 int get_rock_ridge_filename(struct iso_directory_record *de,
 120                             char *retname, struct inode *inode)
 121 {
 122         struct rock_state rs;
 123         struct rock_ridge *rr;
 124         int sig;
 125         int retnamlen = 0;
 126         int truncate = 0;
 127         int ret = 0;
 128
 129         if (!ISOFS_SB(inode->i_sb)->s_rock)
 130                 return 0;
 131         *retname = 0;
 132
 133         init_rock_state(&rs, inode);
 134         setup_rock_ridge(de, inode, &rs);
 135 repeat:
 136
 137         while (rs.len > 2) { /* There may be one byte for padding somewhere */
 138                 rr = (struct rock_ridge *)rs.chr;
 139                 if (rr->len < 3)
 140                         goto out;       /* Something got screwed up here */
 141                 sig = isonum_721(rs.chr);
 142                 rs.chr += rr->len;
 143                 rs.len -= rr->len;
 144                 if (rs.len < 0)
 145                         goto out;       /* corrupted isofs */
 146
 147                 switch (sig) {
 148                 case SIG('R', 'R'):
 149                         if ((rr->u.RR.flags[0] & RR_NM) == 0)
 150                                 goto out;
 151                         break;
 152                 case SIG('S', 'P'):
 153                         if (check_sp(rr, inode))
 154                                 goto out;
 155                         break;
 156                 case SIG('C', 'E'):
 157                         rs.cont_extent = isonum_733(rr->u.CE.extent);
 158                         rs.cont_offset = isonum_733(rr->u.CE.offset);
 159                         rs.cont_size = isonum_733(rr->u.CE.size);
 160                         break;
 161                 case SIG('N', 'M'):
 162                         if (truncate)
 163                                 break;
 164                         if (rr->len < 5)
 165                                 break;
 166                         /*
 167                          * If the flags are 2 or 4, this indicates '.' or '..'.
 168                          * We don't want to do anything with this, because it
 169                          * screws up the code that calls us.  We don't really
 170                          * care anyways, since we can just use the non-RR
 171                          * name.
 172                          */
 173                         if (rr->u.NM.flags & 6)
 174                                 break;
 175
 176                         if (rr->u.NM.flags & ~1) {
 177                                 printk("Unsupported NM flag settings (%d)\n",
 178                                         rr->u.NM.flags);
 179                                 break;
 180                         }
 181                         if ((strlen(retname) + rr->len - 5) >= 254) {
 182                                 truncate = 1;
 183                                 break;
 184                         }
 185                         strncat(retname, rr->u.NM.name, rr->len - 5);
 186                         retnamlen += rr->len - 5;
 187                         break;
 188                 case SIG('R', 'E'):
 189                         kfree(rs.buffer);
 190                         return -1;
 191                 default:
 192                         break;
 193                 }
 194         }
 195         ret = rock_continue(&rs);
 196         if (ret == 0)
 197                 goto repeat;
 198         if (ret == 1)
 199                 return retnamlen; /* If 0, this file did not have a NM field */
 200 out:
 201         kfree(rs.buffer);
 202         return ret;
 203 }
 204
 205 static int
 206 parse_rock_ridge_inode_internal(struct iso_directory_record *de,
 207                                 struct inode *inode, int regard_xa)
 208 {
 209         int symlink_len = 0;
 210         int cnt, sig;
 211         struct inode *reloc;
 212         struct rock_ridge *rr;
 213         int rootflag;
 214         struct rock_state rs;
 215         int ret = 0;
 216
 217         if (!ISOFS_SB(inode->i_sb)->s_rock)
 218                 return 0;
 219
 220         init_rock_state(&rs, inode);
 221         setup_rock_ridge(de, inode, &rs);
 222         if (regard_xa) {
 223                 rs.chr += 14;
 224                 rs.len -= 14;
 225                 if (rs.len < 0)
 226                         rs.len = 0;
 227         }
 228
 229 repeat:
 230         while (rs.len > 2) { /* There may be one byte for padding somewhere */
 231                 rr = (struct rock_ridge *)rs.chr;
 232                 if (rr->len < 3)
 233                         goto out;       /* Something got screwed up here */
 234                 sig = isonum_721(rs.chr);
 235                 rs.chr += rr->len;
 236                 rs.len -= rr->len;
 237                 if (rs.len < 0)
 238                         goto out;       /* corrupted isofs */
 239
 240                 switch (sig) {
 241 #ifndef CONFIG_ZISOFS           /* No flag for SF or ZF */
 242                 case SIG('R', 'R'):
 243                         if ((rr->u.RR.flags[0] &
 244                              (RR_PX | RR_TF | RR_SL | RR_CL)) == 0)
 245                                 goto out;
 246                         break;
 247 #endif
 248                 case SIG('S', 'P'):
 249                         if (check_sp(rr, inode))
 250                                 goto out;
 251                         break;
 252                 case SIG('C', 'E'):
 253                         rs.cont_extent = isonum_733(rr->u.CE.extent);
 254                         rs.cont_offset = isonum_733(rr->u.CE.offset);
 255                         rs.cont_size = isonum_733(rr->u.CE.size);
 256                         break;
 257                 case SIG('E', 'R'):
 258                         ISOFS_SB(inode->i_sb)->s_rock = 1;
 259                         printk(KERN_DEBUG "ISO 9660 Extensions: ");
 260                         {
 261                                 int p;
 262                                 for (p = 0; p < rr->u.ER.len_id; p++)
 263                                         printk("%c", rr->u.ER.data[p]);
 264                         }
 265                         printk("\n");
 266                         break;
 267                 case SIG('P', 'X'):
 268                         inode->i_mode = isonum_733(rr->u.PX.mode);
 269                         inode->i_nlink = isonum_733(rr->u.PX.n_links);
 270                         inode->i_uid = isonum_733(rr->u.PX.uid);
 271                         inode->i_gid = isonum_733(rr->u.PX.gid);
 272                         break;
 273                 case SIG('P', 'N'):
 274                         {
 275                                 int high, low;
 276                                 high = isonum_733(rr->u.PN.dev_high);
 277                                 low = isonum_733(rr->u.PN.dev_low);
 278                                 /*
 279                                  * The Rock Ridge standard specifies that if
 280                                  * sizeof(dev_t) <= 4, then the high field is
 281                                  * unused, and the device number is completely
 282                                  * stored in the low field.  Some writers may
 283                                  * ignore this subtlety,
 284                                  * and as a result we test to see if the entire
 285                                  * device number is
 286                                  * stored in the low field, and use that.
 287                                  */
 288                                 if ((low & ~0xff) && high == 0) {
 289                                         inode->i_rdev =
 290                                             MKDEV(low >> 8, low & 0xff);
 291                                 } else {
 292                                         inode->i_rdev =
 293                                             MKDEV(high, low);
 294                                 }
 295                         }
 296                         break;
 297                 case SIG('T', 'F'):
 298                         /*
 299                          * Some RRIP writers incorrectly place ctime in the
 300                          * TF_CREATE field. Try to handle this correctly for
 301                          * either case.
 302                          */
 303                         /* Rock ridge never appears on a High Sierra disk */
 304                         cnt = 0;
 305                         if (rr->u.TF.flags & TF_CREATE) {
 306                                 inode->i_ctime.tv_sec =
 307                                     iso_date(rr->u.TF.times[cnt++].time,
 308                                              0);
 309                                 inode->i_ctime.tv_nsec = 0;
 310                         }
 311                         if (rr->u.TF.flags & TF_MODIFY) {
 312                                 inode->i_mtime.tv_sec =
 313                                     iso_date(rr->u.TF.times[cnt++].time,
 314                                              0);
 315                                 inode->i_mtime.tv_nsec = 0;
 316                         }
 317                         if (rr->u.TF.flags & TF_ACCESS) {
 318                                 inode->i_atime.tv_sec =
 319                                     iso_date(rr->u.TF.times[cnt++].time,
 320                                              0);
 321                                 inode->i_atime.tv_nsec = 0;
 322                         }
 323                         if (rr->u.TF.flags & TF_ATTRIBUTES) {
 324                                 inode->i_ctime.tv_sec =
 325                                     iso_date(rr->u.TF.times[cnt++].time,
 326                                              0);
 327                                 inode->i_ctime.tv_nsec = 0;
 328                         }
 329                         break;
 330                 case SIG('S', 'L'):
 331                         {
 332                                 int slen;
 333                                 struct SL_component *slp;
 334                                 struct SL_component *oldslp;
 335                                 slen = rr->len - 5;
 336                                 slp = &rr->u.SL.link;
 337                                 inode->i_size = symlink_len;
 338                                 while (slen > 1) {
 339                                         rootflag = 0;
 340                                         switch (slp->flags & ~1) {
 341                                         case 0:
 342                                                 inode->i_size +=
 343                                                     slp->len;
 344                                                 break;
 345                                         case 2:
 346                                                 inode->i_size += 1;
 347                                                 break;
 348                                         case 4:
 349                                                 inode->i_size += 2;
 350                                                 break;
 351                                         case 8:
 352                                                 rootflag = 1;
 353                                                 inode->i_size += 1;
 354                                                 break;
 355                                         default:
 356                                                 printk("Symlink component flag "
 357                                                         "not implemented\n");
 358                                         }
 359                                         slen -= slp->len + 2;
 360                                         oldslp = slp;
 361                                         slp = (struct SL_component *)
 362                                                 (((char *)slp) + slp->len + 2);
 363
 364                                         if (slen < 2) {
 365                                                 if (((rr->u.SL.
 366                                                       flags & 1) != 0)
 367                                                     &&
 368                                                     ((oldslp->
 369                                                       flags & 1) == 0))
 370                                                         inode->i_size +=
 371                                                             1;
 372                                                 break;
 373                                         }
 374
 375                                         /*
 376                                          * If this component record isn't
 377                                          * continued, then append a '/'.
 378                                          */
 379                                         if (!rootflag
 380                                             && (oldslp->flags & 1) == 0)
 381                                                 inode->i_size += 1;
 382                                 }
 383                         }
 384                         symlink_len = inode->i_size;
 385                         break;
 386                 case SIG('R', 'E'):
 387                         printk(KERN_WARNING "Attempt to read inode for "
 388                                         "relocated directory\n");
 389                         goto out;
 390                 case SIG('C', 'L'):
 391                         ISOFS_I(inode)->i_first_extent =
 392                             isonum_733(rr->u.CL.location);
 393                         reloc =
 394                             isofs_iget(inode->i_sb,
 395                                        ISOFS_I(inode)->i_first_extent,
 396                                        0);
 397                         if (!reloc)
 398                                 goto out;
 399                         inode->i_mode = reloc->i_mode;
 400                         inode->i_nlink = reloc->i_nlink;
 401                         inode->i_uid = reloc->i_uid;
 402                         inode->i_gid = reloc->i_gid;
 403                         inode->i_rdev = reloc->i_rdev;
 404                         inode->i_size = reloc->i_size;
 405                         inode->i_blocks = reloc->i_blocks;
 406                         inode->i_atime = reloc->i_atime;
 407                         inode->i_ctime = reloc->i_ctime;
 408                         inode->i_mtime = reloc->i_mtime;
 409                         iput(reloc);
 410                         break;
 411 #ifdef CONFIG_ZISOFS
 412                 case SIG('Z', 'F'): {
 413                         int algo;
 414
 415                         if (ISOFS_SB(inode->i_sb)->s_nocompress)
 416                                 break;
 417                         algo = isonum_721(rr->u.ZF.algorithm);
 418                         if (algo == SIG('p', 'z')) {
 419                                 int block_shift =
 420                                         isonum_711(&rr->u.ZF.parms[1]);
 421                                 if (block_shift < PAGE_CACHE_SHIFT
 422                                                 || block_shift > 17) {
 423                                         printk(KERN_WARNING "isofs: "
 424                                                 "Can't handle ZF block "
 425                                                 "size of 2^%d\n",
 426                                                 block_shift);
 427                                 } else {
 428                                         /*
 429                                          * Note: we don't change
 430                                          * i_blocks here
 431                                          */
 432                                         ISOFS_I(inode)->i_file_format =
 433                                                 isofs_file_compressed;
 434                                         /*
 435                                          * Parameters to compression
 436                                          * algorithm (header size,
 437                                          * block size)
 438                                          */
 439                                         ISOFS_I(inode)->i_format_parm[0] =
 440                                                 isonum_711(&rr->u.ZF.parms[0]);
 441                                         ISOFS_I(inode)->i_format_parm[1] =
 442                                                 isonum_711(&rr->u.ZF.parms[1]);
 443                                         inode->i_size =
 444                                             isonum_733(rr->u.ZF.
 445                                                        real_size);
 446                                 }
 447                         } else {
 448                                 printk(KERN_WARNING
 449                                        "isofs: Unknown ZF compression "
 450                                                 "algorithm: %c%c\n",
 451                                        rr->u.ZF.algorithm[0],
 452                                        rr->u.ZF.algorithm[1]);
 453                         }
 454                         break;
 455                 }
 456 #endif
 457                 default:
 458                         break;
 459                 }
 460         }
 461         ret = rock_continue(&rs);
 462         if (ret == 0)
 463                 goto repeat;
 464         if (ret == 1)
 465                 ret = 0;
 466 out:
 467         kfree(rs.buffer);
 468         return ret;
 469 }
 470
 471 static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
 472 {
 473         int slen;
 474         int rootflag;
 475         struct SL_component *oldslp;
 476         struct SL_component *slp;
 477         slen = rr->len - 5;
 478         slp = &rr->u.SL.link;
 479         while (slen > 1) {
 480                 rootflag = 0;
 481                 switch (slp->flags & ~1) {
 482                 case 0:
 483                         if (slp->len > plimit - rpnt)
 484                                 return NULL;
 485                         memcpy(rpnt, slp->text, slp->len);
 486                         rpnt += slp->len;
 487                         break;
 488                 case 2:
 489                         if (rpnt >= plimit)
 490                                 return NULL;
 491                         *rpnt++ = '.';
 492                         break;
 493                 case 4:
 494                         if (2 > plimit - rpnt)
 495                                 return NULL;
 496                         *rpnt++ = '.';
 497                         *rpnt++ = '.';
 498                         break;
 499                 case 8:
 500                         if (rpnt >= plimit)
 501                                 return NULL;
 502                         rootflag = 1;
 503                         *rpnt++ = '/';
 504                         break;
 505                 default:
 506                         printk("Symlink component flag not implemented (%d)\n",
 507                                slp->flags);
 508                 }
 509                 slen -= slp->len + 2;
 510                 oldslp = slp;
 511                 slp = (struct SL_component *)((char *)slp + slp->len + 2);
 512
 513                 if (slen < 2) {
 514                         /*
 515                          * If there is another SL record, and this component
 516                          * record isn't continued, then add a slash.
 517                          */
 518                         if ((!rootflag) && (rr->u.SL.flags & 1) &&
 519                             !(oldslp->flags & 1)) {
 520                                 if (rpnt >= plimit)
 521                                         return NULL;
 522                                 *rpnt++ = '/';
 523                         }
 524                         break;
 525                 }
 526
 527                 /*
 528                  * If this component record isn't continued, then append a '/'.
 529                  */
 530                 if (!rootflag && !(oldslp->flags & 1)) {
 531                         if (rpnt >= plimit)
 532                                 return NULL;
 533                         *rpnt++ = '/';
 534                 }
 535         }
 536         return rpnt;
 537 }
 538
 539 int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode)
 540 {
 541         int result = parse_rock_ridge_inode_internal(de, inode, 0);
 542
 543         /*
 544          * if rockridge flag was reset and we didn't look for attributes
 545          * behind eventual XA attributes, have a look there
 546          */
 547         if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
 548             && (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
 549                 result = parse_rock_ridge_inode_internal(de, inode, 14);
 550         }
 551         return result;
 552 }
 553
 554 /*
 555  * readpage() for symlinks: reads symlink contents into the page and either
 556  * makes it uptodate and returns 0 or returns error (-EIO)
 557  */
 558 static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
 559 {
 560         struct inode *inode = page->mapping->host;
 561         struct iso_inode_info *ei = ISOFS_I(inode);
 562         char *link = kmap(page);
 563         unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
 564         struct buffer_head *bh;
 565         char *rpnt = link;
 566         unsigned char *pnt;
 567         struct iso_directory_record *raw_de;
 568         unsigned long block, offset;
 569         int sig;
 570         struct rock_ridge *rr;
 571         struct rock_state rs;
 572         int ret;
 573
 574         if (!ISOFS_SB(inode->i_sb)->s_rock)
 575                 goto error;
 576
 577         init_rock_state(&rs, inode);
 578         block = ei->i_iget5_block;
 579         lock_kernel();
 580         bh = sb_bread(inode->i_sb, block);
 581         if (!bh)
 582                 goto out_noread;
 583
 584         offset = ei->i_iget5_offset;
 585         pnt = (unsigned char *)bh->b_data + offset;
 586
 587         raw_de = (struct iso_directory_record *)pnt;
 588
 589         /*
 590          * If we go past the end of the buffer, there is some sort of error.
 591          */
 592         if (offset + *pnt > bufsize)
 593                 goto out_bad_span;
 594
 595         /*
 596          * Now test for possible Rock Ridge extensions which will override
 597          * some of these numbers in the inode structure.
 598          */
 599
 600         setup_rock_ridge(raw_de, inode, &rs);
 601
 602 repeat:
 603         while (rs.len > 2) { /* There may be one byte for padding somewhere */
 604                 rr = (struct rock_ridge *)rs.chr;
 605                 if (rr->len < 3)
 606                         goto out;       /* Something got screwed up here */
 607                 sig = isonum_721(rs.chr);
 608                 rs.chr += rr->len;
 609                 rs.len -= rr->len;
 610                 if (rs.len < 0)
 611                         goto out;       /* corrupted isofs */
 612
 613                 switch (sig) {
 614                 case SIG('R', 'R'):
 615                         if ((rr->u.RR.flags[0] & RR_SL) == 0)
 616                                 goto out;
 617                         break;
 618                 case SIG('S', 'P'):
 619                         if (check_sp(rr, inode))
 620                                 goto out;
 621                         break;
 622                 case SIG('S', 'L'):
 623                         rpnt = get_symlink_chunk(rpnt, rr,
 624                                                  link + (PAGE_SIZE - 1));
 625                         if (rpnt == NULL)
 626                                 goto out;
 627                         break;
 628                 case SIG('C', 'E'):
 629                         /* This tells is if there is a continuation record */
 630                         rs.cont_extent = isonum_733(rr->u.CE.extent);
 631                         rs.cont_offset = isonum_733(rr->u.CE.offset);
 632                         rs.cont_size = isonum_733(rr->u.CE.size);
 633                 default:
 634                         break;
 635                 }
 636         }
 637         ret = rock_continue(&rs);
 638         if (ret == 0)
 639                 goto repeat;
 640         if (ret < 0)
 641                 goto fail;
 642
 643         if (rpnt == link)
 644                 goto fail;
 645         brelse(bh);
 646         *rpnt = '\0';
 647         unlock_kernel();
 648         SetPageUptodate(page);
 649         kunmap(page);
 650         unlock_page(page);
 651         return 0;
 652
 653         /* error exit from macro */
 654 out:
 655         kfree(rs.buffer);
 656         goto fail;
 657 out_noread:
 658         printk("unable to read i-node block");
 659         goto fail;
 660 out_bad_span:
 661         printk("symlink spans iso9660 blocks\n");
 662 fail:
 663         brelse(bh);
 664         unlock_kernel();
 665 error:
 666         SetPageError(page);
 667         kunmap(page);
 668         unlock_page(page);
 669         return -EIO;
 670 }
 671
 672 struct address_space_operations isofs_symlink_aops = {
 673         .readpage = rock_ridge_symlink_readpage
 674 };