err.no Git - linux-2.6/blob - 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 struct rock_state {
  26         void *buffer;
  27         unsigned char *chr;
  28         int len;
  29         int cont_size;
  30         int cont_extent;
  31         int cont_offset;
  32         struct inode *inode;
  33 };
  34
  35 /*
  36  * This is a way of ensuring that we have something in the system
  37  *  use fields that is compatible with Rock Ridge.  Return zero on success.
  38  */
  39
  40 static int check_sp(struct rock_ridge *rr, struct inode *inode)
  41 {
  42         if (rr->u.SP.magic[0] != 0xbe)
  43                 return -1;
  44         if (rr->u.SP.magic[1] != 0xef)
  45                 return -1;
  46         ISOFS_SB(inode->i_sb)->s_rock_offset = rr->u.SP.skip;
  47         return 0;
  48 }
  49
  50 static void setup_rock_ridge(struct iso_directory_record *de,
  51                         struct inode *inode, struct rock_state *rs)
  52 {
  53         rs->len = sizeof(struct iso_directory_record) + de->name_len[0];
  54         if (rs->len & 1)
  55                 (rs->len)++;
  56         rs->chr = (unsigned char *)de + rs->len;
  57         rs->len = *((unsigned char *)de) - rs->len;
  58         if (rs->len < 0)
  59                 rs->len = 0;
  60
  61         if (ISOFS_SB(inode->i_sb)->s_rock_offset != -1) {
  62                 rs->len -= ISOFS_SB(inode->i_sb)->s_rock_offset;
  63                 rs->chr += ISOFS_SB(inode->i_sb)->s_rock_offset;
  64                 if (rs->len < 0)
  65                         rs->len = 0;
  66         }
  67 }
  68
  69 static void init_rock_state(struct rock_state *rs, struct inode *inode)
  70 {
  71         memset(rs, 0, sizeof(*rs));
  72         rs->inode = inode;
  73 }
  74
  75 /*
  76  * Returns 0 if the caller should continue scanning, 1 if the scan must end
  77  * and -ve on error.
  78  */
  79 static int rock_continue(struct rock_state *rs)
  80 {
  81         int ret = 1;
  82
  83         kfree(rs->buffer);
  84         rs->buffer = NULL;
  85         if (rs->cont_extent) {
  86                 struct buffer_head *bh;
  87
  88                 rs->buffer = kmalloc(rs->cont_size, GFP_KERNEL);
  89                 if (!rs->buffer) {
  90                         ret = -ENOMEM;
  91                         goto out;
  92                 }
  93                 ret = -EIO;
  94                 bh = sb_bread(rs->inode->i_sb, rs->cont_extent);
  95                 if (bh) {
  96                         memcpy(rs->buffer, bh->b_data + rs->cont_offset,
  97                                         rs->cont_size);
  98                         put_bh(bh);
  99                         rs->chr = rs->buffer;
 100                         rs->len = rs->cont_size;
 101                         rs->cont_extent = 0;
 102                         rs->cont_size = 0;
 103                         rs->cont_offset = 0;
 104                         return 0;
 105                 }
 106                 printk("Unable to read rock-ridge attributes\n");
 107         }
 108 out:
 109         kfree(rs->buffer);
 110         rs->buffer = NULL;
 111         return ret;
 112 }
 113
 114 /* return length of name field; 0: not found, -1: to be ignored */
 115 int get_rock_ridge_filename(struct iso_directory_record *de,
 116                             char *retname, struct inode *inode)
 117 {
 118         struct rock_state rs;
 119         struct rock_ridge *rr;
 120         int sig;
 121         int retnamlen = 0;
 122         int truncate = 0;
 123         int ret = 0;
 124
 125         if (!ISOFS_SB(inode->i_sb)->s_rock)
 126                 return 0;
 127         *retname = 0;
 128
 129         init_rock_state(&rs, inode);
 130         setup_rock_ridge(de, inode, &rs);
 131 repeat:
 132
 133         while (rs.len > 2) { /* There may be one byte for padding somewhere */
 134                 rr = (struct rock_ridge *)rs.chr;
 135                 if (rr->len < 3)
 136                         goto out;       /* Something got screwed up here */
 137                 sig = isonum_721(rs.chr);
 138                 rs.chr += rr->len;
 139                 rs.len -= rr->len;
 140                 if (rs.len < 0)
 141                         goto out;       /* corrupted isofs */
 142
 143                 switch (sig) {
 144                 case SIG('R', 'R'):
 145                         if ((rr->u.RR.flags[0] & RR_NM) == 0)
 146                                 goto out;
 147                         break;
 148                 case SIG('S', 'P'):
 149                         if (check_sp(rr, inode))
 150                                 goto out;
 151                         break;
 152                 case SIG('C', 'E'):
 153                         rs.cont_extent = isonum_733(rr->u.CE.extent);
 154                         rs.cont_offset = isonum_733(rr->u.CE.offset);
 155                         rs.cont_size = isonum_733(rr->u.CE.size);
 156                         break;
 157                 case SIG('N', 'M'):
 158                         if (truncate)
 159                                 break;
 160                         if (rr->len < 5)
 161                                 break;
 162                         /*
 163                          * If the flags are 2 or 4, this indicates '.' or '..'.
 164                          * We don't want to do anything with this, because it
 165                          * screws up the code that calls us.  We don't really
 166                          * care anyways, since we can just use the non-RR
 167                          * name.
 168                          */
 169                         if (rr->u.NM.flags & 6)
 170                                 break;
 171
 172                         if (rr->u.NM.flags & ~1) {
 173                                 printk("Unsupported NM flag settings (%d)\n",
 174                                         rr->u.NM.flags);
 175                                 break;
 176                         }
 177                         if ((strlen(retname) + rr->len - 5) >= 254) {
 178                                 truncate = 1;
 179                                 break;
 180                         }
 181                         strncat(retname, rr->u.NM.name, rr->len - 5);
 182                         retnamlen += rr->len - 5;
 183                         break;
 184                 case SIG('R', 'E'):
 185                         kfree(rs.buffer);
 186                         return -1;
 187                 default:
 188                         break;
 189                 }
 190         }
 191         ret = rock_continue(&rs);
 192         if (ret == 0)
 193                 goto repeat;
 194         if (ret == 1)
 195                 return retnamlen; /* If 0, this file did not have a NM field */
 196 out:
 197         kfree(rs.buffer);
 198         return ret;
 199 }
 200
 201 static int
 202 parse_rock_ridge_inode_internal(struct iso_directory_record *de,
 203                                 struct inode *inode, int regard_xa)
 204 {
 205         int symlink_len = 0;
 206         int cnt, sig;
 207         struct inode *reloc;
 208         struct rock_ridge *rr;
 209         int rootflag;
 210         struct rock_state rs;
 211         int ret = 0;
 212
 213         if (!ISOFS_SB(inode->i_sb)->s_rock)
 214                 return 0;
 215
 216         init_rock_state(&rs, inode);
 217         setup_rock_ridge(de, inode, &rs);
 218         if (regard_xa) {
 219                 rs.chr += 14;
 220                 rs.len -= 14;
 221                 if (rs.len < 0)
 222                         rs.len = 0;
 223         }
 224
 225 repeat:
 226         while (rs.len > 2) { /* There may be one byte for padding somewhere */
 227                 rr = (struct rock_ridge *)rs.chr;
 228                 if (rr->len < 3)
 229                         goto out;       /* Something got screwed up here */
 230                 sig = isonum_721(rs.chr);
 231                 rs.chr += rr->len;
 232                 rs.len -= rr->len;
 233                 if (rs.len < 0)
 234                         goto out;       /* corrupted isofs */
 235
 236                 switch (sig) {
 237 #ifndef CONFIG_ZISOFS           /* No flag for SF or ZF */
 238                 case SIG('R', 'R'):
 239                         if ((rr->u.RR.flags[0] &
 240                              (RR_PX | RR_TF | RR_SL | RR_CL)) == 0)
 241                                 goto out;
 242                         break;
 243 #endif
 244                 case SIG('S', 'P'):
 245                         if (check_sp(rr, inode))
 246                                 goto out;
 247                         break;
 248                 case SIG('C', 'E'):
 249                         rs.cont_extent = isonum_733(rr->u.CE.extent);
 250                         rs.cont_offset = isonum_733(rr->u.CE.offset);
 251                         rs.cont_size = isonum_733(rr->u.CE.size);
 252                         break;
 253                 case SIG('E', 'R'):
 254                         ISOFS_SB(inode->i_sb)->s_rock = 1;
 255                         printk(KERN_DEBUG "ISO 9660 Extensions: ");
 256                         {
 257                                 int p;
 258                                 for (p = 0; p < rr->u.ER.len_id; p++)
 259                                         printk("%c", rr->u.ER.data[p]);
 260                         }
 261                         printk("\n");
 262                         break;
 263                 case SIG('P', 'X'):
 264                         inode->i_mode = isonum_733(rr->u.PX.mode);
 265                         inode->i_nlink = isonum_733(rr->u.PX.n_links);
 266                         inode->i_uid = isonum_733(rr->u.PX.uid);
 267                         inode->i_gid = isonum_733(rr->u.PX.gid);
 268                         break;
 269                 case SIG('P', 'N'):
 270                         {
 271                                 int high, low;
 272                                 high = isonum_733(rr->u.PN.dev_high);
 273                                 low = isonum_733(rr->u.PN.dev_low);
 274                                 /*
 275                                  * The Rock Ridge standard specifies that if
 276                                  * sizeof(dev_t) <= 4, then the high field is
 277                                  * unused, and the device number is completely
 278                                  * stored in the low field.  Some writers may
 279                                  * ignore this subtlety,
 280                                  * and as a result we test to see if the entire
 281                                  * device number is
 282                                  * stored in the low field, and use that.
 283                                  */
 284                                 if ((low & ~0xff) && high == 0) {
 285                                         inode->i_rdev =
 286                                             MKDEV(low >> 8, low & 0xff);
 287                                 } else {
 288                                         inode->i_rdev =
 289                                             MKDEV(high, low);
 290                                 }
 291                         }
 292                         break;
 293                 case SIG('T', 'F'):
 294                         /*
 295                          * Some RRIP writers incorrectly place ctime in the
 296                          * TF_CREATE field. Try to handle this correctly for
 297                          * either case.
 298                          */
 299                         /* Rock ridge never appears on a High Sierra disk */
 300                         cnt = 0;
 301                         if (rr->u.TF.flags & TF_CREATE) {
 302                                 inode->i_ctime.tv_sec =
 303                                     iso_date(rr->u.TF.times[cnt++].time,
 304                                              0);
 305                                 inode->i_ctime.tv_nsec = 0;
 306                         }
 307                         if (rr->u.TF.flags & TF_MODIFY) {
 308                                 inode->i_mtime.tv_sec =
 309                                     iso_date(rr->u.TF.times[cnt++].time,
 310                                              0);
 311                                 inode->i_mtime.tv_nsec = 0;
 312                         }
 313                         if (rr->u.TF.flags & TF_ACCESS) {
 314                                 inode->i_atime.tv_sec =
 315                                     iso_date(rr->u.TF.times[cnt++].time,
 316                                              0);
 317                                 inode->i_atime.tv_nsec = 0;
 318                         }
 319                         if (rr->u.TF.flags & TF_ATTRIBUTES) {
 320                                 inode->i_ctime.tv_sec =
 321                                     iso_date(rr->u.TF.times[cnt++].time,
 322                                              0);
 323                                 inode->i_ctime.tv_nsec = 0;
 324                         }
 325                         break;
 326                 case SIG('S', 'L'):
 327                         {
 328                                 int slen;
 329                                 struct SL_component *slp;
 330                                 struct SL_component *oldslp;
 331                                 slen = rr->len - 5;
 332                                 slp = &rr->u.SL.link;
 333                                 inode->i_size = symlink_len;
 334                                 while (slen > 1) {
 335                                         rootflag = 0;
 336                                         switch (slp->flags & ~1) {
 337                                         case 0:
 338                                                 inode->i_size +=
 339                                                     slp->len;
 340                                                 break;
 341                                         case 2:
 342                                                 inode->i_size += 1;
 343                                                 break;
 344                                         case 4:
 345                                                 inode->i_size += 2;
 346                                                 break;
 347                                         case 8:
 348                                                 rootflag = 1;
 349                                                 inode->i_size += 1;
 350                                                 break;
 351                                         default:
 352                                                 printk("Symlink component flag "
 353                                                         "not implemented\n");
 354                                         }
 355                                         slen -= slp->len + 2;
 356                                         oldslp = slp;
 357                                         slp = (struct SL_component *)
 358                                                 (((char *)slp) + slp->len + 2);
 359
 360                                         if (slen < 2) {
 361                                                 if (((rr->u.SL.
 362                                                       flags & 1) != 0)
 363                                                     &&
 364                                                     ((oldslp->
 365                                                       flags & 1) == 0))
 366                                                         inode->i_size +=
 367                                                             1;
 368                                                 break;
 369                                         }
 370
 371                                         /*
 372                                          * If this component record isn't
 373                                          * continued, then append a '/'.
 374                                          */
 375                                         if (!rootflag
 376                                             && (oldslp->flags & 1) == 0)
 377                                                 inode->i_size += 1;
 378                                 }
 379                         }
 380                         symlink_len = inode->i_size;
 381                         break;
 382                 case SIG('R', 'E'):
 383                         printk(KERN_WARNING "Attempt to read inode for "
 384                                         "relocated directory\n");
 385                         goto out;
 386                 case SIG('C', 'L'):
 387                         ISOFS_I(inode)->i_first_extent =
 388                             isonum_733(rr->u.CL.location);
 389                         reloc =
 390                             isofs_iget(inode->i_sb,
 391                                        ISOFS_I(inode)->i_first_extent,
 392                                        0);
 393                         if (!reloc)
 394                                 goto out;
 395                         inode->i_mode = reloc->i_mode;
 396                         inode->i_nlink = reloc->i_nlink;
 397                         inode->i_uid = reloc->i_uid;
 398                         inode->i_gid = reloc->i_gid;
 399                         inode->i_rdev = reloc->i_rdev;
 400                         inode->i_size = reloc->i_size;
 401                         inode->i_blocks = reloc->i_blocks;
 402                         inode->i_atime = reloc->i_atime;
 403                         inode->i_ctime = reloc->i_ctime;
 404                         inode->i_mtime = reloc->i_mtime;
 405                         iput(reloc);
 406                         break;
 407 #ifdef CONFIG_ZISOFS
 408                 case SIG('Z', 'F'): {
 409                         int algo;
 410
 411                         if (ISOFS_SB(inode->i_sb)->s_nocompress)
 412                                 break;
 413                         algo = isonum_721(rr->u.ZF.algorithm);
 414                         if (algo == SIG('p', 'z')) {
 415                                 int block_shift =
 416                                         isonum_711(&rr->u.ZF.parms[1]);
 417                                 if (block_shift < PAGE_CACHE_SHIFT
 418                                                 || block_shift > 17) {
 419                                         printk(KERN_WARNING "isofs: "
 420                                                 "Can't handle ZF block "
 421                                                 "size of 2^%d\n",
 422                                                 block_shift);
 423                                 } else {
 424                                         /*
 425                                          * Note: we don't change
 426                                          * i_blocks here
 427                                          */
 428                                         ISOFS_I(inode)->i_file_format =
 429                                                 isofs_file_compressed;
 430                                         /*
 431                                          * Parameters to compression
 432                                          * algorithm (header size,
 433                                          * block size)
 434                                          */
 435                                         ISOFS_I(inode)->i_format_parm[0] =
 436                                                 isonum_711(&rr->u.ZF.parms[0]);
 437                                         ISOFS_I(inode)->i_format_parm[1] =
 438                                                 isonum_711(&rr->u.ZF.parms[1]);
 439                                         inode->i_size =
 440                                             isonum_733(rr->u.ZF.
 441                                                        real_size);
 442                                 }
 443                         } else {
 444                                 printk(KERN_WARNING
 445                                        "isofs: Unknown ZF compression "
 446                                                 "algorithm: %c%c\n",
 447                                        rr->u.ZF.algorithm[0],
 448                                        rr->u.ZF.algorithm[1]);
 449                         }
 450                         break;
 451                 }
 452 #endif
 453                 default:
 454                         break;
 455                 }
 456         }
 457         ret = rock_continue(&rs);
 458         if (ret == 0)
 459                 goto repeat;
 460         if (ret == 1)
 461                 ret = 0;
 462 out:
 463         kfree(rs.buffer);
 464         return ret;
 465 }
 466
 467 static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
 468 {
 469         int slen;
 470         int rootflag;
 471         struct SL_component *oldslp;
 472         struct SL_component *slp;
 473         slen = rr->len - 5;
 474         slp = &rr->u.SL.link;
 475         while (slen > 1) {
 476                 rootflag = 0;
 477                 switch (slp->flags & ~1) {
 478                 case 0:
 479                         if (slp->len > plimit - rpnt)
 480                                 return NULL;
 481                         memcpy(rpnt, slp->text, slp->len);
 482                         rpnt += slp->len;
 483                         break;
 484                 case 2:
 485                         if (rpnt >= plimit)
 486                                 return NULL;
 487                         *rpnt++ = '.';
 488                         break;
 489                 case 4:
 490                         if (2 > plimit - rpnt)
 491                                 return NULL;
 492                         *rpnt++ = '.';
 493                         *rpnt++ = '.';
 494                         break;
 495                 case 8:
 496                         if (rpnt >= plimit)
 497                                 return NULL;
 498                         rootflag = 1;
 499                         *rpnt++ = '/';
 500                         break;
 501                 default:
 502                         printk("Symlink component flag not implemented (%d)\n",
 503                                slp->flags);
 504                 }
 505                 slen -= slp->len + 2;
 506                 oldslp = slp;
 507                 slp = (struct SL_component *)((char *)slp + slp->len + 2);
 508
 509                 if (slen < 2) {
 510                         /*
 511                          * If there is another SL record, and this component
 512                          * record isn't continued, then add a slash.
 513                          */
 514                         if ((!rootflag) && (rr->u.SL.flags & 1) &&
 515                             !(oldslp->flags & 1)) {
 516                                 if (rpnt >= plimit)
 517                                         return NULL;
 518                                 *rpnt++ = '/';
 519                         }
 520                         break;
 521                 }
 522
 523                 /*
 524                  * If this component record isn't continued, then append a '/'.
 525                  */
 526                 if (!rootflag && !(oldslp->flags & 1)) {
 527                         if (rpnt >= plimit)
 528                                 return NULL;
 529                         *rpnt++ = '/';
 530                 }
 531         }
 532         return rpnt;
 533 }
 534
 535 int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode)
 536 {
 537         int result = parse_rock_ridge_inode_internal(de, inode, 0);
 538         /* if rockridge flag was reset and we didn't look for attributes
 539          * behind eventual XA attributes, have a look there */
 540         if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
 541             && (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
 542                 result = parse_rock_ridge_inode_internal(de, inode, 14);
 543         }
 544         return result;
 545 }
 546
 547 /* readpage() for symlinks: reads symlink contents into the page and either
 548    makes it uptodate and returns 0 or returns error (-EIO) */
 549
 550 static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
 551 {
 552         struct inode *inode = page->mapping->host;
 553         struct iso_inode_info *ei = ISOFS_I(inode);
 554         char *link = kmap(page);
 555         unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
 556         struct buffer_head *bh;
 557         char *rpnt = link;
 558         unsigned char *pnt;
 559         struct iso_directory_record *raw_de;
 560         unsigned long block, offset;
 561         int sig;
 562         struct rock_ridge *rr;
 563         struct rock_state rs;
 564         int ret;
 565
 566         if (!ISOFS_SB(inode->i_sb)->s_rock)
 567                 goto error;
 568
 569         init_rock_state(&rs, inode);
 570         block = ei->i_iget5_block;
 571         lock_kernel();
 572         bh = sb_bread(inode->i_sb, block);
 573         if (!bh)
 574                 goto out_noread;
 575
 576         offset = ei->i_iget5_offset;
 577         pnt = (unsigned char *)bh->b_data + offset;
 578
 579         raw_de = (struct iso_directory_record *)pnt;
 580
 581         /*
 582          * If we go past the end of the buffer, there is some sort of error.
 583          */
 584         if (offset + *pnt > bufsize)
 585                 goto out_bad_span;
 586
 587         /* Now test for possible Rock Ridge extensions which will override
 588            some of these numbers in the inode structure. */
 589
 590         setup_rock_ridge(raw_de, inode, &rs);
 591
 592 repeat:
 593         while (rs.len > 2) { /* There may be one byte for padding somewhere */
 594                 rr = (struct rock_ridge *)rs.chr;
 595                 if (rr->len < 3)
 596                         goto out;       /* Something got screwed up here */
 597                 sig = isonum_721(rs.chr);
 598                 rs.chr += rr->len;
 599                 rs.len -= rr->len;
 600                 if (rs.len < 0)
 601                         goto out;       /* corrupted isofs */
 602
 603                 switch (sig) {
 604                 case SIG('R', 'R'):
 605                         if ((rr->u.RR.flags[0] & RR_SL) == 0)
 606                                 goto out;
 607                         break;
 608                 case SIG('S', 'P'):
 609                         if (check_sp(rr, inode))
 610                                 goto out;
 611                         break;
 612                 case SIG('S', 'L'):
 613                         rpnt = get_symlink_chunk(rpnt, rr,
 614                                                  link + (PAGE_SIZE - 1));
 615                         if (rpnt == NULL)
 616                                 goto out;
 617                         break;
 618                 case SIG('C', 'E'):
 619                         /* This tells is if there is a continuation record */
 620                         rs.cont_extent = isonum_733(rr->u.CE.extent);
 621                         rs.cont_offset = isonum_733(rr->u.CE.offset);
 622                         rs.cont_size = isonum_733(rr->u.CE.size);
 623                 default:
 624                         break;
 625                 }
 626         }
 627         ret = rock_continue(&rs);
 628         if (ret == 0)
 629                 goto repeat;
 630         if (ret < 0)
 631                 goto fail;
 632
 633         if (rpnt == link)
 634                 goto fail;
 635         brelse(bh);
 636         *rpnt = '\0';
 637         unlock_kernel();
 638         SetPageUptodate(page);
 639         kunmap(page);
 640         unlock_page(page);
 641         return 0;
 642
 643         /* error exit from macro */
 644 out:
 645         kfree(rs.buffer);
 646         goto fail;
 647 out_noread:
 648         printk("unable to read i-node block");
 649         goto fail;
 650 out_bad_span:
 651         printk("symlink spans iso9660 blocks\n");
 652 fail:
 653         brelse(bh);
 654         unlock_kernel();
 655 error:
 656         SetPageError(page);
 657         kunmap(page);
 658         unlock_page(page);
 659         return -EIO;
 660 }
 661
 662 struct address_space_operations isofs_symlink_aops = {
 663         .readpage = rock_ridge_symlink_readpage
 664 };