linux/fs/udf/unicode.c
Andrew Gabbasov c26f6c6157 udf: Fix conversion of 'dstring' fields to UTF8
Commit 9293fcfbc1
("udf: Remove struct ustr as non-needed intermediate storage"),
while getting rid of 'struct ustr', does not take any special care
of 'dstring' fields and effectively use fixed field length instead
of actual string length, encoded in the last byte of the field.

Also, commit 484a10f493
("udf: Merge linux specific translation into CS0 conversion function")
introduced checking of the length of the string being converted,
requiring proper alignment to number of bytes constituing each
character.

The UDF volume identifier is represented as a 32-bytes 'dstring',
and needs to be converted from CS0 to UTF8, while mounting UDF
filesystem. The changes in mentioned commits can in some cases
lead to incorrect handling of volume identifier:
- if the actual string in 'dstring' is of maximal length and
does not have zero bytes separating it from dstring encoded
length in last byte, that last byte may be included in conversion,
thus making incorrect resulting string;
- if the identifier is encoded with 2-bytes characters (compression
code is 16), the length of 31 bytes (32 bytes of field length minus
1 byte of compression code), taken as the string length, is reported
as an incorrect (unaligned) length, and the conversion fails, which
in its turn leads to volume mounting failure.

This patch introduces handling of 'dstring' encoded length field
in udf_CS0toUTF8 function, that is used in all and only cases
when 'dstring' fields are converted. Currently these cases are
processing of Volume Identifier and Volume Set Identifier fields.
The function is also renamed to udf_dstrCS0toUTF8 to distinctly
indicate that it handles 'dstring' input.

Signed-off-by: Andrew Gabbasov <andrew_gabbasov@mentor.com>
Signed-off-by: Jan Kara <jack@suse.cz>
2016-04-25 15:18:50 +02:00

397 lines
8.8 KiB
C

/*
* unicode.c
*
* PURPOSE
* Routines for converting between UTF-8 and OSTA Compressed Unicode.
* Also handles filename mangling
*
* DESCRIPTION
* OSTA Compressed Unicode is explained in the OSTA UDF specification.
* http://www.osta.org/
* UTF-8 is explained in the IETF RFC XXXX.
* ftp://ftp.internic.net/rfc/rfcxxxx.txt
*
* COPYRIGHT
* This file is distributed under the terms of the GNU General Public
* License (GPL). Copies of the GPL can be obtained from:
* ftp://prep.ai.mit.edu/pub/gnu/GPL
* Each contributing author retains all rights to their own work.
*/
#include "udfdecl.h"
#include <linux/kernel.h>
#include <linux/string.h> /* for memset */
#include <linux/nls.h>
#include <linux/crc-itu-t.h>
#include <linux/slab.h>
#include "udf_sb.h"
static int udf_uni2char_utf8(wchar_t uni,
unsigned char *out,
int boundlen)
{
int u_len = 0;
if (boundlen <= 0)
return -ENAMETOOLONG;
if (uni < 0x80) {
out[u_len++] = (unsigned char)uni;
} else if (uni < 0x800) {
if (boundlen < 2)
return -ENAMETOOLONG;
out[u_len++] = (unsigned char)(0xc0 | (uni >> 6));
out[u_len++] = (unsigned char)(0x80 | (uni & 0x3f));
} else {
if (boundlen < 3)
return -ENAMETOOLONG;
out[u_len++] = (unsigned char)(0xe0 | (uni >> 12));
out[u_len++] = (unsigned char)(0x80 | ((uni >> 6) & 0x3f));
out[u_len++] = (unsigned char)(0x80 | (uni & 0x3f));
}
return u_len;
}
static int udf_char2uni_utf8(const unsigned char *in,
int boundlen,
wchar_t *uni)
{
unsigned int utf_char;
unsigned char c;
int utf_cnt, u_len;
utf_char = 0;
utf_cnt = 0;
for (u_len = 0; u_len < boundlen;) {
c = in[u_len++];
/* Complete a multi-byte UTF-8 character */
if (utf_cnt) {
utf_char = (utf_char << 6) | (c & 0x3f);
if (--utf_cnt)
continue;
} else {
/* Check for a multi-byte UTF-8 character */
if (c & 0x80) {
/* Start a multi-byte UTF-8 character */
if ((c & 0xe0) == 0xc0) {
utf_char = c & 0x1f;
utf_cnt = 1;
} else if ((c & 0xf0) == 0xe0) {
utf_char = c & 0x0f;
utf_cnt = 2;
} else if ((c & 0xf8) == 0xf0) {
utf_char = c & 0x07;
utf_cnt = 3;
} else if ((c & 0xfc) == 0xf8) {
utf_char = c & 0x03;
utf_cnt = 4;
} else if ((c & 0xfe) == 0xfc) {
utf_char = c & 0x01;
utf_cnt = 5;
} else {
utf_cnt = -1;
break;
}
continue;
} else {
/* Single byte UTF-8 character (most common) */
utf_char = c;
}
}
*uni = utf_char;
break;
}
if (utf_cnt) {
*uni = '?';
return -EINVAL;
}
return u_len;
}
#define ILLEGAL_CHAR_MARK '_'
#define EXT_MARK '.'
#define CRC_MARK '#'
#define EXT_SIZE 5
/* Number of chars we need to store generated CRC to make filename unique */
#define CRC_LEN 5
static int udf_name_conv_char(uint8_t *str_o, int str_o_max_len,
int *str_o_idx,
const uint8_t *str_i, int str_i_max_len,
int *str_i_idx,
int u_ch, int *needsCRC,
int (*conv_f)(wchar_t, unsigned char *, int),
int translate)
{
uint32_t c;
int illChar = 0;
int len, gotch = 0;
for (; (!gotch) && (*str_i_idx < str_i_max_len); *str_i_idx += u_ch) {
if (*str_o_idx >= str_o_max_len) {
*needsCRC = 1;
return gotch;
}
/* Expand OSTA compressed Unicode to Unicode */
c = str_i[*str_i_idx];
if (u_ch > 1)
c = (c << 8) | str_i[*str_i_idx + 1];
if (translate && (c == '/' || c == 0))
illChar = 1;
else if (illChar)
break;
else
gotch = 1;
}
if (illChar) {
*needsCRC = 1;
c = ILLEGAL_CHAR_MARK;
gotch = 1;
}
if (gotch) {
len = conv_f(c, &str_o[*str_o_idx], str_o_max_len - *str_o_idx);
/* Valid character? */
if (len >= 0)
*str_o_idx += len;
else if (len == -ENAMETOOLONG) {
*needsCRC = 1;
gotch = 0;
} else {
str_o[(*str_o_idx)++] = '?';
*needsCRC = 1;
}
}
return gotch;
}
static int udf_name_from_CS0(uint8_t *str_o, int str_max_len,
const uint8_t *ocu, int ocu_len,
int (*conv_f)(wchar_t, unsigned char *, int),
int translate)
{
uint32_t c;
uint8_t cmp_id;
int idx, len;
int u_ch;
int needsCRC = 0;
int ext_i_len, ext_max_len;
int str_o_len = 0; /* Length of resulting output */
int ext_o_len = 0; /* Extension output length */
int ext_crc_len = 0; /* Extension output length if used with CRC */
int i_ext = -1; /* Extension position in input buffer */
int o_crc = 0; /* Rightmost possible output pos for CRC+ext */
unsigned short valueCRC;
uint8_t ext[EXT_SIZE * NLS_MAX_CHARSET_SIZE + 1];
uint8_t crc[CRC_LEN];
if (str_max_len <= 0)
return 0;
if (ocu_len == 0) {
memset(str_o, 0, str_max_len);
return 0;
}
cmp_id = ocu[0];
if (cmp_id != 8 && cmp_id != 16) {
memset(str_o, 0, str_max_len);
pr_err("unknown compression code (%d)\n", cmp_id);
return -EINVAL;
}
u_ch = cmp_id >> 3;
ocu++;
ocu_len--;
if (ocu_len % u_ch) {
pr_err("incorrect filename length (%d)\n", ocu_len + 1);
return -EINVAL;
}
if (translate) {
/* Look for extension */
for (idx = ocu_len - u_ch, ext_i_len = 0;
(idx >= 0) && (ext_i_len < EXT_SIZE);
idx -= u_ch, ext_i_len++) {
c = ocu[idx];
if (u_ch > 1)
c = (c << 8) | ocu[idx + 1];
if (c == EXT_MARK) {
if (ext_i_len)
i_ext = idx;
break;
}
}
if (i_ext >= 0) {
/* Convert extension */
ext_max_len = min_t(int, sizeof(ext), str_max_len);
ext[ext_o_len++] = EXT_MARK;
idx = i_ext + u_ch;
while (udf_name_conv_char(ext, ext_max_len, &ext_o_len,
ocu, ocu_len, &idx,
u_ch, &needsCRC,
conv_f, translate)) {
if ((ext_o_len + CRC_LEN) < str_max_len)
ext_crc_len = ext_o_len;
}
}
}
idx = 0;
while (1) {
if (translate && (idx == i_ext)) {
if (str_o_len > (str_max_len - ext_o_len))
needsCRC = 1;
break;
}
if (!udf_name_conv_char(str_o, str_max_len, &str_o_len,
ocu, ocu_len, &idx,
u_ch, &needsCRC, conv_f, translate))
break;
if (translate &&
(str_o_len <= (str_max_len - ext_o_len - CRC_LEN)))
o_crc = str_o_len;
}
if (translate) {
if (str_o_len <= 2 && str_o[0] == '.' &&
(str_o_len == 1 || str_o[1] == '.'))
needsCRC = 1;
if (needsCRC) {
str_o_len = o_crc;
valueCRC = crc_itu_t(0, ocu, ocu_len);
crc[0] = CRC_MARK;
crc[1] = hex_asc_upper_hi(valueCRC >> 8);
crc[2] = hex_asc_upper_lo(valueCRC >> 8);
crc[3] = hex_asc_upper_hi(valueCRC);
crc[4] = hex_asc_upper_lo(valueCRC);
len = min_t(int, CRC_LEN, str_max_len - str_o_len);
memcpy(&str_o[str_o_len], crc, len);
str_o_len += len;
ext_o_len = ext_crc_len;
}
if (ext_o_len > 0) {
memcpy(&str_o[str_o_len], ext, ext_o_len);
str_o_len += ext_o_len;
}
}
return str_o_len;
}
static int udf_name_to_CS0(uint8_t *ocu, int ocu_max_len,
const uint8_t *str_i, int str_len,
int (*conv_f)(const unsigned char *, int, wchar_t *))
{
int i, len;
unsigned int max_val;
wchar_t uni_char;
int u_len, u_ch;
if (ocu_max_len <= 0)
return 0;
memset(ocu, 0, ocu_max_len);
ocu[0] = 8;
max_val = 0xff;
u_ch = 1;
try_again:
u_len = 1;
for (i = 0; i < str_len; i++) {
/* Name didn't fit? */
if (u_len + u_ch > ocu_max_len)
return 0;
len = conv_f(&str_i[i], str_len - i, &uni_char);
if (!len)
continue;
/* Invalid character, deal with it */
if (len < 0) {
len = 1;
uni_char = '?';
}
if (uni_char > max_val) {
max_val = 0xffff;
ocu[0] = 0x10;
u_ch = 2;
goto try_again;
}
if (max_val == 0xffff)
ocu[u_len++] = (uint8_t)(uni_char >> 8);
ocu[u_len++] = (uint8_t)(uni_char & 0xff);
i += len - 1;
}
return u_len;
}
int udf_dstrCS0toUTF8(uint8_t *utf_o, int o_len,
const uint8_t *ocu_i, int i_len)
{
int s_len = 0;
if (i_len > 0) {
s_len = ocu_i[i_len - 1];
if (s_len >= i_len) {
pr_err("incorrect dstring lengths (%d/%d)\n",
s_len, i_len);
return -EINVAL;
}
}
return udf_name_from_CS0(utf_o, o_len, ocu_i, s_len,
udf_uni2char_utf8, 0);
}
int udf_get_filename(struct super_block *sb, const uint8_t *sname, int slen,
uint8_t *dname, int dlen)
{
int (*conv_f)(wchar_t, unsigned char *, int);
int ret;
if (!slen)
return -EIO;
if (dlen <= 0)
return 0;
if (UDF_QUERY_FLAG(sb, UDF_FLAG_UTF8)) {
conv_f = udf_uni2char_utf8;
} else if (UDF_QUERY_FLAG(sb, UDF_FLAG_NLS_MAP)) {
conv_f = UDF_SB(sb)->s_nls_map->uni2char;
} else
BUG();
ret = udf_name_from_CS0(dname, dlen, sname, slen, conv_f, 1);
/* Zero length filename isn't valid... */
if (ret == 0)
ret = -EINVAL;
return ret;
}
int udf_put_filename(struct super_block *sb, const uint8_t *sname, int slen,
uint8_t *dname, int dlen)
{
int (*conv_f)(const unsigned char *, int, wchar_t *);
if (UDF_QUERY_FLAG(sb, UDF_FLAG_UTF8)) {
conv_f = udf_char2uni_utf8;
} else if (UDF_QUERY_FLAG(sb, UDF_FLAG_NLS_MAP)) {
conv_f = UDF_SB(sb)->s_nls_map->char2uni;
} else
BUG();
return udf_name_to_CS0(dname, dlen, sname, slen, conv_f);
}