1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/fs/isofs/rock.c
4  *
5  *  (C) 1992, 1993  Eric Youngdale
6  *
7  *  Rock Ridge Extensions to iso9660
8  */
9 
10 #include <linux/slab.h>
11 #include <linux/pagemap.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 	int cont_loops;
35 	struct inode *inode;
36 };
37 
38 /*
39  * This is a way of ensuring that we have something in the system
40  * use fields that is compatible with Rock Ridge.  Return zero on success.
41  */
42 
check_sp(struct rock_ridge * rr,struct inode * inode)43 static int check_sp(struct rock_ridge *rr, struct inode *inode)
44 {
45 	if (rr->u.SP.magic[0] != 0xbe)
46 		return -1;
47 	if (rr->u.SP.magic[1] != 0xef)
48 		return -1;
49 	ISOFS_SB(inode->i_sb)->s_rock_offset = rr->u.SP.skip;
50 	return 0;
51 }
52 
setup_rock_ridge(struct iso_directory_record * de,struct inode * inode,struct rock_state * rs)53 static void setup_rock_ridge(struct iso_directory_record *de,
54 			struct inode *inode, struct rock_state *rs)
55 {
56 	rs->len = sizeof(struct iso_directory_record) + de->name_len[0];
57 	if (rs->len & 1)
58 		(rs->len)++;
59 	rs->chr = (unsigned char *)de + rs->len;
60 	rs->len = *((unsigned char *)de) - rs->len;
61 	if (rs->len < 0)
62 		rs->len = 0;
63 
64 	if (ISOFS_SB(inode->i_sb)->s_rock_offset != -1) {
65 		rs->len -= ISOFS_SB(inode->i_sb)->s_rock_offset;
66 		rs->chr += ISOFS_SB(inode->i_sb)->s_rock_offset;
67 		if (rs->len < 0)
68 			rs->len = 0;
69 	}
70 }
71 
init_rock_state(struct rock_state * rs,struct inode * inode)72 static void init_rock_state(struct rock_state *rs, struct inode *inode)
73 {
74 	memset(rs, 0, sizeof(*rs));
75 	rs->inode = inode;
76 }
77 
78 /* Maximum number of Rock Ridge continuation entries */
79 #define RR_MAX_CE_ENTRIES 32
80 
81 /*
82  * Returns 0 if the caller should continue scanning, 1 if the scan must end
83  * and -ve on error.
84  */
rock_continue(struct rock_state * rs)85 static int rock_continue(struct rock_state *rs)
86 {
87 	int ret = 1;
88 	int blocksize = 1 << rs->inode->i_blkbits;
89 	const int min_de_size = offsetof(struct rock_ridge, u);
90 
91 	kfree(rs->buffer);
92 	rs->buffer = NULL;
93 
94 	if ((unsigned)rs->cont_offset > blocksize - min_de_size ||
95 	    (unsigned)rs->cont_size > blocksize ||
96 	    (unsigned)(rs->cont_offset + rs->cont_size) > blocksize) {
97 		printk(KERN_NOTICE "rock: corrupted directory entry. "
98 			"extent=%d, offset=%d, size=%d\n",
99 			rs->cont_extent, rs->cont_offset, rs->cont_size);
100 		ret = -EIO;
101 		goto out;
102 	}
103 
104 	if (rs->cont_extent) {
105 		struct buffer_head *bh;
106 
107 		rs->buffer = kmalloc(rs->cont_size, GFP_KERNEL);
108 		if (!rs->buffer) {
109 			ret = -ENOMEM;
110 			goto out;
111 		}
112 		ret = -EIO;
113 		if (++rs->cont_loops >= RR_MAX_CE_ENTRIES)
114 			goto out;
115 		bh = sb_bread(rs->inode->i_sb, rs->cont_extent);
116 		if (bh) {
117 			memcpy(rs->buffer, bh->b_data + rs->cont_offset,
118 					rs->cont_size);
119 			put_bh(bh);
120 			rs->chr = rs->buffer;
121 			rs->len = rs->cont_size;
122 			rs->cont_extent = 0;
123 			rs->cont_size = 0;
124 			rs->cont_offset = 0;
125 			return 0;
126 		}
127 		printk("Unable to read rock-ridge attributes\n");
128 	}
129 out:
130 	kfree(rs->buffer);
131 	rs->buffer = NULL;
132 	return ret;
133 }
134 
135 /*
136  * We think there's a record of type `sig' at rs->chr.  Parse the signature
137  * and make sure that there's really room for a record of that type.
138  */
rock_check_overflow(struct rock_state * rs,int sig)139 static int rock_check_overflow(struct rock_state *rs, int sig)
140 {
141 	int len;
142 
143 	switch (sig) {
144 	case SIG('S', 'P'):
145 		len = sizeof(struct SU_SP_s);
146 		break;
147 	case SIG('C', 'E'):
148 		len = sizeof(struct SU_CE_s);
149 		break;
150 	case SIG('E', 'R'):
151 		len = sizeof(struct SU_ER_s);
152 		break;
153 	case SIG('R', 'R'):
154 		len = sizeof(struct RR_RR_s);
155 		break;
156 	case SIG('P', 'X'):
157 		len = sizeof(struct RR_PX_s);
158 		break;
159 	case SIG('P', 'N'):
160 		len = sizeof(struct RR_PN_s);
161 		break;
162 	case SIG('S', 'L'):
163 		len = sizeof(struct RR_SL_s);
164 		break;
165 	case SIG('N', 'M'):
166 		len = sizeof(struct RR_NM_s);
167 		break;
168 	case SIG('C', 'L'):
169 		len = sizeof(struct RR_CL_s);
170 		break;
171 	case SIG('P', 'L'):
172 		len = sizeof(struct RR_PL_s);
173 		break;
174 	case SIG('T', 'F'):
175 		len = sizeof(struct RR_TF_s);
176 		break;
177 	case SIG('Z', 'F'):
178 		len = sizeof(struct RR_ZF_s);
179 		break;
180 	default:
181 		len = 0;
182 		break;
183 	}
184 	len += offsetof(struct rock_ridge, u);
185 	if (len > rs->len) {
186 		printk(KERN_NOTICE "rock: directory entry would overflow "
187 				"storage\n");
188 		printk(KERN_NOTICE "rock: sig=0x%02x, size=%d, remaining=%d\n",
189 				sig, len, rs->len);
190 		return -EIO;
191 	}
192 	return 0;
193 }
194 
195 /*
196  * return length of name field; 0: not found, -1: to be ignored
197  */
get_rock_ridge_filename(struct iso_directory_record * de,char * retname,struct inode * inode)198 int get_rock_ridge_filename(struct iso_directory_record *de,
199 			    char *retname, struct inode *inode)
200 {
201 	struct rock_state rs;
202 	struct rock_ridge *rr;
203 	int sig;
204 	int retnamlen = 0;
205 	int truncate = 0;
206 	int ret = 0;
207 	char *p;
208 	int len;
209 
210 	if (!ISOFS_SB(inode->i_sb)->s_rock)
211 		return 0;
212 	*retname = 0;
213 
214 	init_rock_state(&rs, inode);
215 	setup_rock_ridge(de, inode, &rs);
216 repeat:
217 
218 	while (rs.len > 2) { /* There may be one byte for padding somewhere */
219 		rr = (struct rock_ridge *)rs.chr;
220 		/*
221 		 * Ignore rock ridge info if rr->len is out of range, but
222 		 * don't return -EIO because that would make the file
223 		 * invisible.
224 		 */
225 		if (rr->len < 3)
226 			goto out;	/* Something got screwed up here */
227 		sig = isonum_721(rs.chr);
228 		if (rock_check_overflow(&rs, sig))
229 			goto eio;
230 		rs.chr += rr->len;
231 		rs.len -= rr->len;
232 		/*
233 		 * As above, just ignore the rock ridge info if rr->len
234 		 * is bogus.
235 		 */
236 		if (rs.len < 0)
237 			goto out;	/* Something got screwed up here */
238 
239 		switch (sig) {
240 		case SIG('R', 'R'):
241 			if ((rr->u.RR.flags[0] & RR_NM) == 0)
242 				goto out;
243 			break;
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('N', 'M'):
254 			if (truncate)
255 				break;
256 			if (rr->len < 5)
257 				break;
258 			/*
259 			 * If the flags are 2 or 4, this indicates '.' or '..'.
260 			 * We don't want to do anything with this, because it
261 			 * screws up the code that calls us.  We don't really
262 			 * care anyways, since we can just use the non-RR
263 			 * name.
264 			 */
265 			if (rr->u.NM.flags & 6)
266 				break;
267 
268 			if (rr->u.NM.flags & ~1) {
269 				printk("Unsupported NM flag settings (%d)\n",
270 					rr->u.NM.flags);
271 				break;
272 			}
273 			len = rr->len - 5;
274 			if (retnamlen + len >= 254) {
275 				truncate = 1;
276 				break;
277 			}
278 			p = memchr(rr->u.NM.name, '\0', len);
279 			if (unlikely(p))
280 				len = p - rr->u.NM.name;
281 			memcpy(retname + retnamlen, rr->u.NM.name, len);
282 			retnamlen += len;
283 			retname[retnamlen] = '\0';
284 			break;
285 		case SIG('R', 'E'):
286 			kfree(rs.buffer);
287 			return -1;
288 		default:
289 			break;
290 		}
291 	}
292 	ret = rock_continue(&rs);
293 	if (ret == 0)
294 		goto repeat;
295 	if (ret == 1)
296 		return retnamlen; /* If 0, this file did not have a NM field */
297 out:
298 	kfree(rs.buffer);
299 	return ret;
300 eio:
301 	ret = -EIO;
302 	goto out;
303 }
304 
305 #define RR_REGARD_XA 1
306 #define RR_RELOC_DE 2
307 
308 static int
parse_rock_ridge_inode_internal(struct iso_directory_record * de,struct inode * inode,int flags)309 parse_rock_ridge_inode_internal(struct iso_directory_record *de,
310 				struct inode *inode, int flags)
311 {
312 	int symlink_len = 0;
313 	int cnt, sig;
314 	unsigned int reloc_block;
315 	struct inode *reloc;
316 	struct rock_ridge *rr;
317 	int rootflag;
318 	struct rock_state rs;
319 	int ret = 0;
320 
321 	if (!ISOFS_SB(inode->i_sb)->s_rock)
322 		return 0;
323 
324 	init_rock_state(&rs, inode);
325 	setup_rock_ridge(de, inode, &rs);
326 	if (flags & RR_REGARD_XA) {
327 		rs.chr += 14;
328 		rs.len -= 14;
329 		if (rs.len < 0)
330 			rs.len = 0;
331 	}
332 
333 repeat:
334 	while (rs.len > 2) { /* There may be one byte for padding somewhere */
335 		rr = (struct rock_ridge *)rs.chr;
336 		/*
337 		 * Ignore rock ridge info if rr->len is out of range, but
338 		 * don't return -EIO because that would make the file
339 		 * invisible.
340 		 */
341 		if (rr->len < 3)
342 			goto out;	/* Something got screwed up here */
343 		sig = isonum_721(rs.chr);
344 		if (rock_check_overflow(&rs, sig))
345 			goto eio;
346 		rs.chr += rr->len;
347 		rs.len -= rr->len;
348 		/*
349 		 * As above, just ignore the rock ridge info if rr->len
350 		 * is bogus.
351 		 */
352 		if (rs.len < 0)
353 			goto out;	/* Something got screwed up here */
354 
355 		switch (sig) {
356 #ifndef CONFIG_ZISOFS		/* No flag for SF or ZF */
357 		case SIG('R', 'R'):
358 			if ((rr->u.RR.flags[0] &
359 			     (RR_PX | RR_TF | RR_SL | RR_CL)) == 0)
360 				goto out;
361 			break;
362 #endif
363 		case SIG('S', 'P'):
364 			if (check_sp(rr, inode))
365 				goto out;
366 			break;
367 		case SIG('C', 'E'):
368 			rs.cont_extent = isonum_733(rr->u.CE.extent);
369 			rs.cont_offset = isonum_733(rr->u.CE.offset);
370 			rs.cont_size = isonum_733(rr->u.CE.size);
371 			break;
372 		case SIG('E', 'R'):
373 			/* Invalid length of ER tag id? */
374 			if (rr->u.ER.len_id + offsetof(struct rock_ridge, u.ER.data) > rr->len)
375 				goto out;
376 			ISOFS_SB(inode->i_sb)->s_rock = 1;
377 			printk(KERN_DEBUG "ISO 9660 Extensions: ");
378 			{
379 				int p;
380 				for (p = 0; p < rr->u.ER.len_id; p++)
381 					printk(KERN_CONT "%c", rr->u.ER.data[p]);
382 			}
383 			printk(KERN_CONT "\n");
384 			break;
385 		case SIG('P', 'X'):
386 			inode->i_mode = isonum_733(rr->u.PX.mode);
387 			set_nlink(inode, isonum_733(rr->u.PX.n_links));
388 			i_uid_write(inode, isonum_733(rr->u.PX.uid));
389 			i_gid_write(inode, isonum_733(rr->u.PX.gid));
390 			break;
391 		case SIG('P', 'N'):
392 			{
393 				int high, low;
394 				high = isonum_733(rr->u.PN.dev_high);
395 				low = isonum_733(rr->u.PN.dev_low);
396 				/*
397 				 * The Rock Ridge standard specifies that if
398 				 * sizeof(dev_t) <= 4, then the high field is
399 				 * unused, and the device number is completely
400 				 * stored in the low field.  Some writers may
401 				 * ignore this subtlety,
402 				 * and as a result we test to see if the entire
403 				 * device number is
404 				 * stored in the low field, and use that.
405 				 */
406 				if ((low & ~0xff) && high == 0) {
407 					inode->i_rdev =
408 					    MKDEV(low >> 8, low & 0xff);
409 				} else {
410 					inode->i_rdev =
411 					    MKDEV(high, low);
412 				}
413 			}
414 			break;
415 		case SIG('T', 'F'):
416 			/*
417 			 * Some RRIP writers incorrectly place ctime in the
418 			 * TF_CREATE field. Try to handle this correctly for
419 			 * either case.
420 			 */
421 			/* Rock ridge never appears on a High Sierra disk */
422 			cnt = 0;
423 			if (rr->u.TF.flags & TF_CREATE) {
424 				inode->i_ctime.tv_sec =
425 				    iso_date(rr->u.TF.times[cnt++].time,
426 					     0);
427 				inode->i_ctime.tv_nsec = 0;
428 			}
429 			if (rr->u.TF.flags & TF_MODIFY) {
430 				inode->i_mtime.tv_sec =
431 				    iso_date(rr->u.TF.times[cnt++].time,
432 					     0);
433 				inode->i_mtime.tv_nsec = 0;
434 			}
435 			if (rr->u.TF.flags & TF_ACCESS) {
436 				inode->i_atime.tv_sec =
437 				    iso_date(rr->u.TF.times[cnt++].time,
438 					     0);
439 				inode->i_atime.tv_nsec = 0;
440 			}
441 			if (rr->u.TF.flags & TF_ATTRIBUTES) {
442 				inode->i_ctime.tv_sec =
443 				    iso_date(rr->u.TF.times[cnt++].time,
444 					     0);
445 				inode->i_ctime.tv_nsec = 0;
446 			}
447 			break;
448 		case SIG('S', 'L'):
449 			{
450 				int slen;
451 				struct SL_component *slp;
452 				struct SL_component *oldslp;
453 				slen = rr->len - 5;
454 				slp = &rr->u.SL.link;
455 				inode->i_size = symlink_len;
456 				while (slen > 1) {
457 					rootflag = 0;
458 					switch (slp->flags & ~1) {
459 					case 0:
460 						inode->i_size +=
461 						    slp->len;
462 						break;
463 					case 2:
464 						inode->i_size += 1;
465 						break;
466 					case 4:
467 						inode->i_size += 2;
468 						break;
469 					case 8:
470 						rootflag = 1;
471 						inode->i_size += 1;
472 						break;
473 					default:
474 						printk("Symlink component flag "
475 							"not implemented\n");
476 					}
477 					slen -= slp->len + 2;
478 					oldslp = slp;
479 					slp = (struct SL_component *)
480 						(((char *)slp) + slp->len + 2);
481 
482 					if (slen < 2) {
483 						if (((rr->u.SL.
484 						      flags & 1) != 0)
485 						    &&
486 						    ((oldslp->
487 						      flags & 1) == 0))
488 							inode->i_size +=
489 							    1;
490 						break;
491 					}
492 
493 					/*
494 					 * If this component record isn't
495 					 * continued, then append a '/'.
496 					 */
497 					if (!rootflag
498 					    && (oldslp->flags & 1) == 0)
499 						inode->i_size += 1;
500 				}
501 			}
502 			symlink_len = inode->i_size;
503 			break;
504 		case SIG('R', 'E'):
505 			printk(KERN_WARNING "Attempt to read inode for "
506 					"relocated directory\n");
507 			goto out;
508 		case SIG('C', 'L'):
509 			if (flags & RR_RELOC_DE) {
510 				printk(KERN_ERR
511 				       "ISOFS: Recursive directory relocation "
512 				       "is not supported\n");
513 				goto eio;
514 			}
515 			reloc_block = isonum_733(rr->u.CL.location);
516 			if (reloc_block == ISOFS_I(inode)->i_iget5_block &&
517 			    ISOFS_I(inode)->i_iget5_offset == 0) {
518 				printk(KERN_ERR
519 				       "ISOFS: Directory relocation points to "
520 				       "itself\n");
521 				goto eio;
522 			}
523 			ISOFS_I(inode)->i_first_extent = reloc_block;
524 			reloc = isofs_iget_reloc(inode->i_sb, reloc_block, 0);
525 			if (IS_ERR(reloc)) {
526 				ret = PTR_ERR(reloc);
527 				goto out;
528 			}
529 			inode->i_mode = reloc->i_mode;
530 			set_nlink(inode, reloc->i_nlink);
531 			inode->i_uid = reloc->i_uid;
532 			inode->i_gid = reloc->i_gid;
533 			inode->i_rdev = reloc->i_rdev;
534 			inode->i_size = reloc->i_size;
535 			inode->i_blocks = reloc->i_blocks;
536 			inode->i_atime = reloc->i_atime;
537 			inode->i_ctime = reloc->i_ctime;
538 			inode->i_mtime = reloc->i_mtime;
539 			iput(reloc);
540 			break;
541 #ifdef CONFIG_ZISOFS
542 		case SIG('Z', 'F'): {
543 			int algo;
544 
545 			if (ISOFS_SB(inode->i_sb)->s_nocompress)
546 				break;
547 			algo = isonum_721(rr->u.ZF.algorithm);
548 			if (algo == SIG('p', 'z')) {
549 				int block_shift =
550 					isonum_711(&rr->u.ZF.parms[1]);
551 				if (block_shift > 17) {
552 					printk(KERN_WARNING "isofs: "
553 						"Can't handle ZF block "
554 						"size of 2^%d\n",
555 						block_shift);
556 				} else {
557 					/*
558 					 * Note: we don't change
559 					 * i_blocks here
560 					 */
561 					ISOFS_I(inode)->i_file_format =
562 						isofs_file_compressed;
563 					/*
564 					 * Parameters to compression
565 					 * algorithm (header size,
566 					 * block size)
567 					 */
568 					ISOFS_I(inode)->i_format_parm[0] =
569 						isonum_711(&rr->u.ZF.parms[0]);
570 					ISOFS_I(inode)->i_format_parm[1] =
571 						isonum_711(&rr->u.ZF.parms[1]);
572 					inode->i_size =
573 					    isonum_733(rr->u.ZF.
574 						       real_size);
575 				}
576 			} else {
577 				printk(KERN_WARNING
578 				       "isofs: Unknown ZF compression "
579 						"algorithm: %c%c\n",
580 				       rr->u.ZF.algorithm[0],
581 				       rr->u.ZF.algorithm[1]);
582 			}
583 			break;
584 		}
585 #endif
586 		default:
587 			break;
588 		}
589 	}
590 	ret = rock_continue(&rs);
591 	if (ret == 0)
592 		goto repeat;
593 	if (ret == 1)
594 		ret = 0;
595 out:
596 	kfree(rs.buffer);
597 	return ret;
598 eio:
599 	ret = -EIO;
600 	goto out;
601 }
602 
get_symlink_chunk(char * rpnt,struct rock_ridge * rr,char * plimit)603 static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
604 {
605 	int slen;
606 	int rootflag;
607 	struct SL_component *oldslp;
608 	struct SL_component *slp;
609 	slen = rr->len - 5;
610 	slp = &rr->u.SL.link;
611 	while (slen > 1) {
612 		rootflag = 0;
613 		switch (slp->flags & ~1) {
614 		case 0:
615 			if (slp->len > plimit - rpnt)
616 				return NULL;
617 			memcpy(rpnt, slp->text, slp->len);
618 			rpnt += slp->len;
619 			break;
620 		case 2:
621 			if (rpnt >= plimit)
622 				return NULL;
623 			*rpnt++ = '.';
624 			break;
625 		case 4:
626 			if (2 > plimit - rpnt)
627 				return NULL;
628 			*rpnt++ = '.';
629 			*rpnt++ = '.';
630 			break;
631 		case 8:
632 			if (rpnt >= plimit)
633 				return NULL;
634 			rootflag = 1;
635 			*rpnt++ = '/';
636 			break;
637 		default:
638 			printk("Symlink component flag not implemented (%d)\n",
639 			       slp->flags);
640 		}
641 		slen -= slp->len + 2;
642 		oldslp = slp;
643 		slp = (struct SL_component *)((char *)slp + slp->len + 2);
644 
645 		if (slen < 2) {
646 			/*
647 			 * If there is another SL record, and this component
648 			 * record isn't continued, then add a slash.
649 			 */
650 			if ((!rootflag) && (rr->u.SL.flags & 1) &&
651 			    !(oldslp->flags & 1)) {
652 				if (rpnt >= plimit)
653 					return NULL;
654 				*rpnt++ = '/';
655 			}
656 			break;
657 		}
658 
659 		/*
660 		 * If this component record isn't continued, then append a '/'.
661 		 */
662 		if (!rootflag && !(oldslp->flags & 1)) {
663 			if (rpnt >= plimit)
664 				return NULL;
665 			*rpnt++ = '/';
666 		}
667 	}
668 	return rpnt;
669 }
670 
parse_rock_ridge_inode(struct iso_directory_record * de,struct inode * inode,int relocated)671 int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode,
672 			   int relocated)
673 {
674 	int flags = relocated ? RR_RELOC_DE : 0;
675 	int result = parse_rock_ridge_inode_internal(de, inode, flags);
676 
677 	/*
678 	 * if rockridge flag was reset and we didn't look for attributes
679 	 * behind eventual XA attributes, have a look there
680 	 */
681 	if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
682 	    && (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
683 		result = parse_rock_ridge_inode_internal(de, inode,
684 							 flags | RR_REGARD_XA);
685 	}
686 	return result;
687 }
688 
689 /*
690  * readpage() for symlinks: reads symlink contents into the page and either
691  * makes it uptodate and returns 0 or returns error (-EIO)
692  */
rock_ridge_symlink_readpage(struct file * file,struct page * page)693 static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
694 {
695 	struct inode *inode = page->mapping->host;
696 	struct iso_inode_info *ei = ISOFS_I(inode);
697 	struct isofs_sb_info *sbi = ISOFS_SB(inode->i_sb);
698 	char *link = page_address(page);
699 	unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
700 	struct buffer_head *bh;
701 	char *rpnt = link;
702 	unsigned char *pnt;
703 	struct iso_directory_record *raw_de;
704 	unsigned long block, offset;
705 	int sig;
706 	struct rock_ridge *rr;
707 	struct rock_state rs;
708 	int ret;
709 
710 	if (!sbi->s_rock)
711 		goto error;
712 
713 	init_rock_state(&rs, inode);
714 	block = ei->i_iget5_block;
715 	bh = sb_bread(inode->i_sb, block);
716 	if (!bh)
717 		goto out_noread;
718 
719 	offset = ei->i_iget5_offset;
720 	pnt = (unsigned char *)bh->b_data + offset;
721 
722 	raw_de = (struct iso_directory_record *)pnt;
723 
724 	/*
725 	 * If we go past the end of the buffer, there is some sort of error.
726 	 */
727 	if (offset + *pnt > bufsize)
728 		goto out_bad_span;
729 
730 	/*
731 	 * Now test for possible Rock Ridge extensions which will override
732 	 * some of these numbers in the inode structure.
733 	 */
734 
735 	setup_rock_ridge(raw_de, inode, &rs);
736 
737 repeat:
738 	while (rs.len > 2) { /* There may be one byte for padding somewhere */
739 		rr = (struct rock_ridge *)rs.chr;
740 		if (rr->len < 3)
741 			goto out;	/* Something got screwed up here */
742 		sig = isonum_721(rs.chr);
743 		if (rock_check_overflow(&rs, sig))
744 			goto out;
745 		rs.chr += rr->len;
746 		rs.len -= rr->len;
747 		if (rs.len < 0)
748 			goto out;	/* corrupted isofs */
749 
750 		switch (sig) {
751 		case SIG('R', 'R'):
752 			if ((rr->u.RR.flags[0] & RR_SL) == 0)
753 				goto out;
754 			break;
755 		case SIG('S', 'P'):
756 			if (check_sp(rr, inode))
757 				goto out;
758 			break;
759 		case SIG('S', 'L'):
760 			rpnt = get_symlink_chunk(rpnt, rr,
761 						 link + (PAGE_SIZE - 1));
762 			if (rpnt == NULL)
763 				goto out;
764 			break;
765 		case SIG('C', 'E'):
766 			/* This tells is if there is a continuation record */
767 			rs.cont_extent = isonum_733(rr->u.CE.extent);
768 			rs.cont_offset = isonum_733(rr->u.CE.offset);
769 			rs.cont_size = isonum_733(rr->u.CE.size);
770 			break;
771 		default:
772 			break;
773 		}
774 	}
775 	ret = rock_continue(&rs);
776 	if (ret == 0)
777 		goto repeat;
778 	if (ret < 0)
779 		goto fail;
780 
781 	if (rpnt == link)
782 		goto fail;
783 	brelse(bh);
784 	*rpnt = '\0';
785 	SetPageUptodate(page);
786 	unlock_page(page);
787 	return 0;
788 
789 	/* error exit from macro */
790 out:
791 	kfree(rs.buffer);
792 	goto fail;
793 out_noread:
794 	printk("unable to read i-node block");
795 	goto fail;
796 out_bad_span:
797 	printk("symlink spans iso9660 blocks\n");
798 fail:
799 	brelse(bh);
800 error:
801 	SetPageError(page);
802 	unlock_page(page);
803 	return -EIO;
804 }
805 
806 const struct address_space_operations isofs_symlink_aops = {
807 	.readpage = rock_ridge_symlink_readpage
808 };
809