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linux/fs/isofs/rock.c

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// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/isofs/rock.c
*
* (C) 1992, 1993 Eric Youngdale
*
* Rock Ridge Extensions to iso9660
*/
#include <linux/slab.h>
#include <linux/pagemap.h>
#include "isofs.h"
#include "rock.h"
/*
* These functions are designed to read the system areas of a directory record
* and extract relevant information. There are different functions provided
* depending upon what information we need at the time. One function fills
* out an inode structure, a second one extracts a filename, a third one
* returns a symbolic link name, and a fourth one returns the extent number
* for the file.
*/
#define SIG(A,B) ((A) | ((B) << 8)) /* isonum_721() */
struct rock_state {
void *buffer;
unsigned char *chr;
int len;
int cont_size;
int cont_extent;
int cont_offset;
int cont_loops;
struct inode *inode;
};
/*
* This is a way of ensuring that we have something in the system
* use fields that is compatible with Rock Ridge. Return zero on success.
*/
static int check_sp(struct rock_ridge *rr, struct inode *inode)
{
if (rr->u.SP.magic[0] != 0xbe)
return -1;
if (rr->u.SP.magic[1] != 0xef)
return -1;
ISOFS_SB(inode->i_sb)->s_rock_offset = rr->u.SP.skip;
return 0;
}
static void setup_rock_ridge(struct iso_directory_record *de,
struct inode *inode, struct rock_state *rs)
{
rs->len = sizeof(struct iso_directory_record) + de->name_len[0];
if (rs->len & 1)
(rs->len)++;
rs->chr = (unsigned char *)de + rs->len;
rs->len = *((unsigned char *)de) - rs->len;
if (rs->len < 0)
rs->len = 0;
if (ISOFS_SB(inode->i_sb)->s_rock_offset != -1) {
rs->len -= ISOFS_SB(inode->i_sb)->s_rock_offset;
rs->chr += ISOFS_SB(inode->i_sb)->s_rock_offset;
if (rs->len < 0)
rs->len = 0;
}
}
static void init_rock_state(struct rock_state *rs, struct inode *inode)
{
memset(rs, 0, sizeof(*rs));
rs->inode = inode;
}
/* Maximum number of Rock Ridge continuation entries */
#define RR_MAX_CE_ENTRIES 32
/*
* Returns 0 if the caller should continue scanning, 1 if the scan must end
* and -ve on error.
*/
static int rock_continue(struct rock_state *rs)
{
int ret = 1;
int blocksize = 1 << rs->inode->i_blkbits;
const int min_de_size = offsetof(struct rock_ridge, u);
kfree(rs->buffer);
rs->buffer = NULL;
if ((unsigned)rs->cont_offset > blocksize - min_de_size ||
(unsigned)rs->cont_size > blocksize ||
(unsigned)(rs->cont_offset + rs->cont_size) > blocksize) {
printk(KERN_NOTICE "rock: corrupted directory entry. "
"extent=%d, offset=%d, size=%d\n",
rs->cont_extent, rs->cont_offset, rs->cont_size);
ret = -EIO;
goto out;
}
if (rs->cont_extent) {
struct buffer_head *bh;
rs->buffer = kmalloc(rs->cont_size, GFP_KERNEL);
if (!rs->buffer) {
ret = -ENOMEM;
goto out;
}
ret = -EIO;
if (++rs->cont_loops >= RR_MAX_CE_ENTRIES)
goto out;
bh = sb_bread(rs->inode->i_sb, rs->cont_extent);
if (bh) {
memcpy(rs->buffer, bh->b_data + rs->cont_offset,
rs->cont_size);
put_bh(bh);
rs->chr = rs->buffer;
rs->len = rs->cont_size;
rs->cont_extent = 0;
rs->cont_size = 0;
rs->cont_offset = 0;
return 0;
}
printk("Unable to read rock-ridge attributes\n");
}
out:
kfree(rs->buffer);
rs->buffer = NULL;
return ret;
}
/*
* We think there's a record of type `sig' at rs->chr. Parse the signature
* and make sure that there's really room for a record of that type.
*/
static int rock_check_overflow(struct rock_state *rs, int sig)
{
int len;
switch (sig) {
case SIG('S', 'P'):
len = sizeof(struct SU_SP_s);
break;
case SIG('C', 'E'):
len = sizeof(struct SU_CE_s);
break;
case SIG('E', 'R'):
len = sizeof(struct SU_ER_s);
break;
case SIG('R', 'R'):
len = sizeof(struct RR_RR_s);
break;
case SIG('P', 'X'):
len = sizeof(struct RR_PX_s);
break;
case SIG('P', 'N'):
len = sizeof(struct RR_PN_s);
break;
case SIG('S', 'L'):
len = sizeof(struct RR_SL_s);
break;
case SIG('N', 'M'):
len = sizeof(struct RR_NM_s);
break;
case SIG('C', 'L'):
len = sizeof(struct RR_CL_s);
break;
case SIG('P', 'L'):
len = sizeof(struct RR_PL_s);
break;
case SIG('T', 'F'):
len = sizeof(struct RR_TF_s);
break;
case SIG('Z', 'F'):
len = sizeof(struct RR_ZF_s);
break;
default:
len = 0;
break;
}
len += offsetof(struct rock_ridge, u);
if (len > rs->len) {
printk(KERN_NOTICE "rock: directory entry would overflow "
"storage\n");
printk(KERN_NOTICE "rock: sig=0x%02x, size=%d, remaining=%d\n",
sig, len, rs->len);
return -EIO;
}
return 0;
}
/*
* return length of name field; 0: not found, -1: to be ignored
*/
int get_rock_ridge_filename(struct iso_directory_record *de,
char *retname, struct inode *inode)
{
struct rock_state rs;
struct rock_ridge *rr;
int sig;
int retnamlen = 0;
int truncate = 0;
int ret = 0;
char *p;
int len;
if (!ISOFS_SB(inode->i_sb)->s_rock)
return 0;
*retname = 0;
init_rock_state(&rs, inode);
setup_rock_ridge(de, inode, &rs);
repeat:
while (rs.len > 2) { /* There may be one byte for padding somewhere */
rr = (struct rock_ridge *)rs.chr;
/*
* Ignore rock ridge info if rr->len is out of range, but
* don't return -EIO because that would make the file
* invisible.
*/
if (rr->len < 3)
goto out; /* Something got screwed up here */
sig = isonum_721(rs.chr);
if (rock_check_overflow(&rs, sig))
goto eio;
rs.chr += rr->len;
rs.len -= rr->len;
/*
* As above, just ignore the rock ridge info if rr->len
* is bogus.
*/
if (rs.len < 0)
goto out; /* Something got screwed up here */
switch (sig) {
case SIG('R', 'R'):
if ((rr->u.RR.flags[0] & RR_NM) == 0)
goto out;
break;
case SIG('S', 'P'):
if (check_sp(rr, inode))
goto out;
break;
case SIG('C', 'E'):
rs.cont_extent = isonum_733(rr->u.CE.extent);
rs.cont_offset = isonum_733(rr->u.CE.offset);
rs.cont_size = isonum_733(rr->u.CE.size);
break;
case SIG('N', 'M'):
if (truncate)
break;
if (rr->len < 5)
break;
/*
* If the flags are 2 or 4, this indicates '.' or '..'.
* We don't want to do anything with this, because it
* screws up the code that calls us. We don't really
* care anyways, since we can just use the non-RR
* name.
*/
if (rr->u.NM.flags & 6)
break;
if (rr->u.NM.flags & ~1) {
printk("Unsupported NM flag settings (%d)\n",
rr->u.NM.flags);
break;
}
len = rr->len - 5;
if (retnamlen + len >= 254) {
truncate = 1;
break;
}
p = memchr(rr->u.NM.name, '\0', len);
if (unlikely(p))
len = p - rr->u.NM.name;
memcpy(retname + retnamlen, rr->u.NM.name, len);
retnamlen += len;
retname[retnamlen] = '\0';
break;
case SIG('R', 'E'):
kfree(rs.buffer);
return -1;
default:
break;
}
}
ret = rock_continue(&rs);
if (ret == 0)
goto repeat;
if (ret == 1)
return retnamlen; /* If 0, this file did not have a NM field */
out:
kfree(rs.buffer);
return ret;
eio:
ret = -EIO;
goto out;
}
#define RR_REGARD_XA 1
#define RR_RELOC_DE 2
static int
parse_rock_ridge_inode_internal(struct iso_directory_record *de,
struct inode *inode, int flags)
{
int symlink_len = 0;
int cnt, sig;
unsigned int reloc_block;
struct inode *reloc;
struct rock_ridge *rr;
int rootflag;
struct rock_state rs;
int ret = 0;
if (!ISOFS_SB(inode->i_sb)->s_rock)
return 0;
init_rock_state(&rs, inode);
setup_rock_ridge(de, inode, &rs);
if (flags & RR_REGARD_XA) {
rs.chr += 14;
rs.len -= 14;
if (rs.len < 0)
rs.len = 0;
}
repeat:
while (rs.len > 2) { /* There may be one byte for padding somewhere */
rr = (struct rock_ridge *)rs.chr;
/*
* Ignore rock ridge info if rr->len is out of range, but
* don't return -EIO because that would make the file
* invisible.
*/
if (rr->len < 3)
goto out; /* Something got screwed up here */
sig = isonum_721(rs.chr);
if (rock_check_overflow(&rs, sig))
goto eio;
rs.chr += rr->len;
rs.len -= rr->len;
/*
* As above, just ignore the rock ridge info if rr->len
* is bogus.
*/
if (rs.len < 0)
goto out; /* Something got screwed up here */
switch (sig) {
#ifndef CONFIG_ZISOFS /* No flag for SF or ZF */
case SIG('R', 'R'):
if ((rr->u.RR.flags[0] &
(RR_PX | RR_TF | RR_SL | RR_CL)) == 0)
goto out;
break;
#endif
case SIG('S', 'P'):
if (check_sp(rr, inode))
goto out;
break;
case SIG('C', 'E'):
rs.cont_extent = isonum_733(rr->u.CE.extent);
rs.cont_offset = isonum_733(rr->u.CE.offset);
rs.cont_size = isonum_733(rr->u.CE.size);
break;
case SIG('E', 'R'):
/* Invalid length of ER tag id? */
if (rr->u.ER.len_id + offsetof(struct rock_ridge, u.ER.data) > rr->len)
goto out;
ISOFS_SB(inode->i_sb)->s_rock = 1;
printk(KERN_DEBUG "ISO 9660 Extensions: ");
{
int p;
for (p = 0; p < rr->u.ER.len_id; p++)
printk(KERN_CONT "%c", rr->u.ER.data[p]);
}
printk(KERN_CONT "\n");
break;
case SIG('P', 'X'):
inode->i_mode = isonum_733(rr->u.PX.mode);
set_nlink(inode, isonum_733(rr->u.PX.n_links));
i_uid_write(inode, isonum_733(rr->u.PX.uid));
i_gid_write(inode, isonum_733(rr->u.PX.gid));
break;
case SIG('P', 'N'):
{
int high, low;
high = isonum_733(rr->u.PN.dev_high);
low = isonum_733(rr->u.PN.dev_low);
/*
* The Rock Ridge standard specifies that if
* sizeof(dev_t) <= 4, then the high field is
* unused, and the device number is completely
* stored in the low field. Some writers may
* ignore this subtlety,
* and as a result we test to see if the entire
* device number is
* stored in the low field, and use that.
*/
if ((low & ~0xff) && high == 0) {
inode->i_rdev =
MKDEV(low >> 8, low & 0xff);
} else {
inode->i_rdev =
MKDEV(high, low);
}
}
break;
case SIG('T', 'F'):
/*
* Some RRIP writers incorrectly place ctime in the
* TF_CREATE field. Try to handle this correctly for
* either case.
*/
/* Rock ridge never appears on a High Sierra disk */
cnt = 0;
if (rr->u.TF.flags & TF_CREATE) {
inode->i_ctime.tv_sec =
iso_date(rr->u.TF.times[cnt++].time,
0);
inode->i_ctime.tv_nsec = 0;
}
if (rr->u.TF.flags & TF_MODIFY) {
inode->i_mtime.tv_sec =
iso_date(rr->u.TF.times[cnt++].time,
0);
inode->i_mtime.tv_nsec = 0;
}
if (rr->u.TF.flags & TF_ACCESS) {
inode->i_atime.tv_sec =
iso_date(rr->u.TF.times[cnt++].time,
0);
inode->i_atime.tv_nsec = 0;
}
if (rr->u.TF.flags & TF_ATTRIBUTES) {
inode->i_ctime.tv_sec =
iso_date(rr->u.TF.times[cnt++].time,
0);
inode->i_ctime.tv_nsec = 0;
}
break;
case SIG('S', 'L'):
{
int slen;
struct SL_component *slp;
struct SL_component *oldslp;
slen = rr->len - 5;
slp = &rr->u.SL.link;
inode->i_size = symlink_len;
while (slen > 1) {
rootflag = 0;
switch (slp->flags & ~1) {
case 0:
inode->i_size +=
slp->len;
break;
case 2:
inode->i_size += 1;
break;
case 4:
inode->i_size += 2;
break;
case 8:
rootflag = 1;
inode->i_size += 1;
break;
default:
printk("Symlink component flag "
"not implemented\n");
}
slen -= slp->len + 2;
oldslp = slp;
slp = (struct SL_component *)
(((char *)slp) + slp->len + 2);
if (slen < 2) {
if (((rr->u.SL.
flags & 1) != 0)
&&
((oldslp->
flags & 1) == 0))
inode->i_size +=
1;
break;
}
/*
* If this component record isn't
* continued, then append a '/'.
*/
if (!rootflag
&& (oldslp->flags & 1) == 0)
inode->i_size += 1;
}
}
symlink_len = inode->i_size;
break;
case SIG('R', 'E'):
printk(KERN_WARNING "Attempt to read inode for "
"relocated directory\n");
goto out;
case SIG('C', 'L'):
if (flags & RR_RELOC_DE) {
printk(KERN_ERR
"ISOFS: Recursive directory relocation "
"is not supported\n");
goto eio;
}
reloc_block = isonum_733(rr->u.CL.location);
if (reloc_block == ISOFS_I(inode)->i_iget5_block &&
ISOFS_I(inode)->i_iget5_offset == 0) {
printk(KERN_ERR
"ISOFS: Directory relocation points to "
"itself\n");
goto eio;
}
ISOFS_I(inode)->i_first_extent = reloc_block;
reloc = isofs_iget_reloc(inode->i_sb, reloc_block, 0);
if (IS_ERR(reloc)) {
ret = PTR_ERR(reloc);
goto out;
}
inode->i_mode = reloc->i_mode;
set_nlink(inode, reloc->i_nlink);
inode->i_uid = reloc->i_uid;
inode->i_gid = reloc->i_gid;
inode->i_rdev = reloc->i_rdev;
inode->i_size = reloc->i_size;
inode->i_blocks = reloc->i_blocks;
inode->i_atime = reloc->i_atime;
inode->i_ctime = reloc->i_ctime;
inode->i_mtime = reloc->i_mtime;
iput(reloc);
break;
#ifdef CONFIG_ZISOFS
case SIG('Z', 'F'): {
int algo;
if (ISOFS_SB(inode->i_sb)->s_nocompress)
break;
algo = isonum_721(rr->u.ZF.algorithm);
if (algo == SIG('p', 'z')) {
int block_shift =
isonum_711(&rr->u.ZF.parms[1]);
if (block_shift > 17) {
printk(KERN_WARNING "isofs: "
"Can't handle ZF block "
"size of 2^%d\n",
block_shift);
} else {
/*
* Note: we don't change
* i_blocks here
*/
ISOFS_I(inode)->i_file_format =
isofs_file_compressed;
/*
* Parameters to compression
* algorithm (header size,
* block size)
*/
ISOFS_I(inode)->i_format_parm[0] =
isonum_711(&rr->u.ZF.parms[0]);
ISOFS_I(inode)->i_format_parm[1] =
isonum_711(&rr->u.ZF.parms[1]);
inode->i_size =
isonum_733(rr->u.ZF.
real_size);
}
} else {
printk(KERN_WARNING
"isofs: Unknown ZF compression "
"algorithm: %c%c\n",
rr->u.ZF.algorithm[0],
rr->u.ZF.algorithm[1]);
}
break;
}
#endif
default:
break;
}
}
ret = rock_continue(&rs);
if (ret == 0)
goto repeat;
if (ret == 1)
ret = 0;
out:
kfree(rs.buffer);
return ret;
eio:
ret = -EIO;
goto out;
}
static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
{
int slen;
int rootflag;
struct SL_component *oldslp;
struct SL_component *slp;
slen = rr->len - 5;
slp = &rr->u.SL.link;
while (slen > 1) {
rootflag = 0;
switch (slp->flags & ~1) {
case 0:
if (slp->len > plimit - rpnt)
return NULL;
memcpy(rpnt, slp->text, slp->len);
rpnt += slp->len;
break;
case 2:
if (rpnt >= plimit)
return NULL;
*rpnt++ = '.';
break;
case 4:
if (2 > plimit - rpnt)
return NULL;
*rpnt++ = '.';
*rpnt++ = '.';
break;
case 8:
if (rpnt >= plimit)
return NULL;
rootflag = 1;
*rpnt++ = '/';
break;
default:
printk("Symlink component flag not implemented (%d)\n",
slp->flags);
}
slen -= slp->len + 2;
oldslp = slp;
slp = (struct SL_component *)((char *)slp + slp->len + 2);
if (slen < 2) {
/*
* If there is another SL record, and this component
* record isn't continued, then add a slash.
*/
if ((!rootflag) && (rr->u.SL.flags & 1) &&
!(oldslp->flags & 1)) {
if (rpnt >= plimit)
return NULL;
*rpnt++ = '/';
}
break;
}
/*
* If this component record isn't continued, then append a '/'.
*/
if (!rootflag && !(oldslp->flags & 1)) {
if (rpnt >= plimit)
return NULL;
*rpnt++ = '/';
}
}
return rpnt;
}
int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode,
int relocated)
{
int flags = relocated ? RR_RELOC_DE : 0;
int result = parse_rock_ridge_inode_internal(de, inode, flags);
/*
* if rockridge flag was reset and we didn't look for attributes
* behind eventual XA attributes, have a look there
*/
if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
&& (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
result = parse_rock_ridge_inode_internal(de, inode,
flags | RR_REGARD_XA);
}
return result;
}
/*
* readpage() for symlinks: reads symlink contents into the page and either
* makes it uptodate and returns 0 or returns error (-EIO)
*/
static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
{
struct inode *inode = page->mapping->host;
struct iso_inode_info *ei = ISOFS_I(inode);
struct isofs_sb_info *sbi = ISOFS_SB(inode->i_sb);
char *link = page_address(page);
unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
struct buffer_head *bh;
char *rpnt = link;
unsigned char *pnt;
struct iso_directory_record *raw_de;
unsigned long block, offset;
int sig;
struct rock_ridge *rr;
struct rock_state rs;
int ret;
if (!sbi->s_rock)
goto error;
init_rock_state(&rs, inode);
block = ei->i_iget5_block;
bh = sb_bread(inode->i_sb, block);
if (!bh)
goto out_noread;
offset = ei->i_iget5_offset;
pnt = (unsigned char *)bh->b_data + offset;
raw_de = (struct iso_directory_record *)pnt;
/*
* If we go past the end of the buffer, there is some sort of error.
*/
if (offset + *pnt > bufsize)
goto out_bad_span;
/*
* Now test for possible Rock Ridge extensions which will override
* some of these numbers in the inode structure.
*/
setup_rock_ridge(raw_de, inode, &rs);
repeat:
while (rs.len > 2) { /* There may be one byte for padding somewhere */
rr = (struct rock_ridge *)rs.chr;
if (rr->len < 3)
goto out; /* Something got screwed up here */
sig = isonum_721(rs.chr);
if (rock_check_overflow(&rs, sig))
goto out;
rs.chr += rr->len;
rs.len -= rr->len;
if (rs.len < 0)
goto out; /* corrupted isofs */
switch (sig) {
case SIG('R', 'R'):
if ((rr->u.RR.flags[0] & RR_SL) == 0)
goto out;
break;
case SIG('S', 'P'):
if (check_sp(rr, inode))
goto out;
break;
case SIG('S', 'L'):
rpnt = get_symlink_chunk(rpnt, rr,
link + (PAGE_SIZE - 1));
if (rpnt == NULL)
goto out;
break;
case SIG('C', 'E'):
/* This tells is if there is a continuation record */
rs.cont_extent = isonum_733(rr->u.CE.extent);
rs.cont_offset = isonum_733(rr->u.CE.offset);
rs.cont_size = isonum_733(rr->u.CE.size);
default:
break;
}
}
ret = rock_continue(&rs);
if (ret == 0)
goto repeat;
if (ret < 0)
goto fail;
if (rpnt == link)
goto fail;
brelse(bh);
*rpnt = '\0';
SetPageUptodate(page);
unlock_page(page);
return 0;
/* error exit from macro */
out:
kfree(rs.buffer);
goto fail;
out_noread:
printk("unable to read i-node block");
goto fail;
out_bad_span:
printk("symlink spans iso9660 blocks\n");
fail:
brelse(bh);
error:
SetPageError(page);
unlock_page(page);
return -EIO;
}
const struct address_space_operations isofs_symlink_aops = {
.readpage = rock_ridge_symlink_readpage
};
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