1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * unicode.c
4 *
5 * PURPOSE
6 * Routines for converting between UTF-8 and OSTA Compressed Unicode.
7 * Also handles filename mangling
8 *
9 * DESCRIPTION
10 * OSTA Compressed Unicode is explained in the OSTA UDF specification.
11 * http://www.osta.org/
12 * UTF-8 is explained in the IETF RFC XXXX.
13 * ftp://ftp.internic.net/rfc/rfcxxxx.txt
14 *
15 */
16
17 #include "udfdecl.h"
18
19 #include <linux/kernel.h>
20 #include <linux/string.h> /* for memset */
21 #include <linux/nls.h>
22 #include <linux/crc-itu-t.h>
23 #include <linux/slab.h>
24
25 #include "udf_sb.h"
26
27 #define PLANE_SIZE 0x10000
28 #define UNICODE_MAX 0x10ffff
29 #define SURROGATE_MASK 0xfffff800
30 #define SURROGATE_PAIR 0x0000d800
31 #define SURROGATE_LOW 0x00000400
32 #define SURROGATE_CHAR_BITS 10
33 #define SURROGATE_CHAR_MASK ((1 << SURROGATE_CHAR_BITS) - 1)
34
35 #define ILLEGAL_CHAR_MARK '_'
36 #define EXT_MARK '.'
37 #define CRC_MARK '#'
38 #define EXT_SIZE 5
39 /* Number of chars we need to store generated CRC to make filename unique */
40 #define CRC_LEN 5
41
42 static unicode_t get_utf16_char(const uint8_t *str_i, int str_i_max_len,
43 int str_i_idx, int u_ch, unicode_t *ret)
44 {
45 unicode_t c;
46 int start_idx = str_i_idx;
47
48 /* Expand OSTA compressed Unicode to Unicode */
49 c = str_i[str_i_idx++];
50 if (u_ch > 1)
51 c = (c << 8) | str_i[str_i_idx++];
52 if ((c & SURROGATE_MASK) == SURROGATE_PAIR) {
53 unicode_t next;
54
55 /* Trailing surrogate char */
56 if (str_i_idx >= str_i_max_len) {
57 c = UNICODE_MAX + 1;
58 goto out;
59 }
60
61 /* Low surrogate must follow the high one... */
62 if (c & SURROGATE_LOW) {
63 c = UNICODE_MAX + 1;
64 goto out;
65 }
66
67 WARN_ON_ONCE(u_ch != 2);
68 next = str_i[str_i_idx++] << 8;
69 next |= str_i[str_i_idx++];
70 if ((next & SURROGATE_MASK) != SURROGATE_PAIR ||
71 !(next & SURROGATE_LOW)) {
72 c = UNICODE_MAX + 1;
73 goto out;
74 }
75
76 c = PLANE_SIZE +
77 ((c & SURROGATE_CHAR_MASK) << SURROGATE_CHAR_BITS) +
78 (next & SURROGATE_CHAR_MASK);
79 }
80 out:
81 *ret = c;
82 return str_i_idx - start_idx;
83 }
84
85
86 static int udf_name_conv_char(uint8_t *str_o, int str_o_max_len,
87 int *str_o_idx,
88 const uint8_t *str_i, int str_i_max_len,
89 int *str_i_idx,
90 int u_ch, int *needsCRC,
91 int (*conv_f)(wchar_t, unsigned char *, int),
92 int translate)
93 {
94 unicode_t c;
95 int illChar = 0;
96 int len, gotch = 0;
97
98 while (!gotch && *str_i_idx < str_i_max_len) {
99 if (*str_o_idx >= str_o_max_len) {
100 *needsCRC = 1;
101 return gotch;
102 }
103
104 len = get_utf16_char(str_i, str_i_max_len, *str_i_idx, u_ch,
105 &c);
106 /* These chars cannot be converted. Replace them. */
107 if (c == 0 || c > UNICODE_MAX || (conv_f && c > MAX_WCHAR_T) ||
108 (translate && c == '/')) {
109 illChar = 1;
110 if (!translate)
111 gotch = 1;
112 } else if (illChar)
113 break;
114 else
115 gotch = 1;
116 *str_i_idx += len;
117 }
118 if (illChar) {
119 *needsCRC = 1;
120 c = ILLEGAL_CHAR_MARK;
121 gotch = 1;
122 }
123 if (gotch) {
124 if (conv_f) {
125 len = conv_f(c, &str_o[*str_o_idx],
126 str_o_max_len - *str_o_idx);
127 } else {
128 len = utf32_to_utf8(c, &str_o[*str_o_idx],
129 str_o_max_len - *str_o_idx);
130 if (len < 0)
131 len = -ENAMETOOLONG;
132 }
133 /* Valid character? */
134 if (len >= 0)
135 *str_o_idx += len;
136 else if (len == -ENAMETOOLONG) {
137 *needsCRC = 1;
138 gotch = 0;
139 } else {
140 str_o[(*str_o_idx)++] = ILLEGAL_CHAR_MARK;
141 *needsCRC = 1;
142 }
143 }
144 return gotch;
145 }
146
147 static int udf_name_from_CS0(struct super_block *sb,
148 uint8_t *str_o, int str_max_len,
149 const uint8_t *ocu, int ocu_len,
150 int translate)
151 {
152 uint32_t c;
153 uint8_t cmp_id;
154 int idx, len;
155 int u_ch;
156 int needsCRC = 0;
157 int ext_i_len, ext_max_len;
158 int str_o_len = 0; /* Length of resulting output */
159 int ext_o_len = 0; /* Extension output length */
160 int ext_crc_len = 0; /* Extension output length if used with CRC */
161 int i_ext = -1; /* Extension position in input buffer */
162 int o_crc = 0; /* Rightmost possible output pos for CRC+ext */
163 unsigned short valueCRC;
164 uint8_t ext[EXT_SIZE * NLS_MAX_CHARSET_SIZE + 1];
165 uint8_t crc[CRC_LEN];
166 int (*conv_f)(wchar_t, unsigned char *, int);
167
168 if (str_max_len <= 0)
169 return 0;
170
171 if (ocu_len == 0) {
172 memset(str_o, 0, str_max_len);
173 return 0;
174 }
175
176 if (UDF_SB(sb)->s_nls_map)
177 conv_f = UDF_SB(sb)->s_nls_map->uni2char;
178 else
179 conv_f = NULL;
180
181 cmp_id = ocu[0];
182 if (cmp_id != 8 && cmp_id != 16) {
183 memset(str_o, 0, str_max_len);
184 pr_err("unknown compression code (%u)\n", cmp_id);
185 return -EINVAL;
186 }
187 u_ch = cmp_id >> 3;
188
189 ocu++;
190 ocu_len--;
191
192 if (ocu_len % u_ch) {
193 pr_err("incorrect filename length (%d)\n", ocu_len + 1);
194 return -EINVAL;
195 }
196
197 if (translate) {
198 /* Look for extension */
199 for (idx = ocu_len - u_ch, ext_i_len = 0;
200 (idx >= 0) && (ext_i_len < EXT_SIZE);
201 idx -= u_ch, ext_i_len++) {
202 c = ocu[idx];
203 if (u_ch > 1)
204 c = (c << 8) | ocu[idx + 1];
205
206 if (c == EXT_MARK) {
207 if (ext_i_len)
208 i_ext = idx;
209 break;
210 }
211 }
212 if (i_ext >= 0) {
213 /* Convert extension */
214 ext_max_len = min_t(int, sizeof(ext), str_max_len);
215 ext[ext_o_len++] = EXT_MARK;
216 idx = i_ext + u_ch;
217 while (udf_name_conv_char(ext, ext_max_len, &ext_o_len,
218 ocu, ocu_len, &idx,
219 u_ch, &needsCRC,
220 conv_f, translate)) {
221 if ((ext_o_len + CRC_LEN) < str_max_len)
222 ext_crc_len = ext_o_len;
223 }
224 }
225 }
226
227 idx = 0;
228 while (1) {
229 if (translate && (idx == i_ext)) {
230 if (str_o_len > (str_max_len - ext_o_len))
231 needsCRC = 1;
232 break;
233 }
234
235 if (!udf_name_conv_char(str_o, str_max_len, &str_o_len,
236 ocu, ocu_len, &idx,
237 u_ch, &needsCRC, conv_f, translate))
238 break;
239
240 if (translate &&
241 (str_o_len <= (str_max_len - ext_o_len - CRC_LEN)))
242 o_crc = str_o_len;
243 }
244
245 if (translate) {
246 if (str_o_len > 0 && str_o_len <= 2 && str_o[0] == '.' &&
247 (str_o_len == 1 || str_o[1] == '.'))
248 needsCRC = 1;
249 if (needsCRC) {
250 str_o_len = o_crc;
251 valueCRC = crc_itu_t(0, ocu, ocu_len);
252 crc[0] = CRC_MARK;
253 crc[1] = hex_asc_upper_hi(valueCRC >> 8);
254 crc[2] = hex_asc_upper_lo(valueCRC >> 8);
255 crc[3] = hex_asc_upper_hi(valueCRC);
256 crc[4] = hex_asc_upper_lo(valueCRC);
257 len = min_t(int, CRC_LEN, str_max_len - str_o_len);
258 memcpy(&str_o[str_o_len], crc, len);
259 str_o_len += len;
260 ext_o_len = ext_crc_len;
261 }
262 if (ext_o_len > 0) {
263 memcpy(&str_o[str_o_len], ext, ext_o_len);
264 str_o_len += ext_o_len;
265 }
266 }
267
268 return str_o_len;
269 }
270
271 static int udf_name_to_CS0(struct super_block *sb,
272 uint8_t *ocu, int ocu_max_len,
273 const uint8_t *str_i, int str_len)
274 {
275 int i, len;
276 unsigned int max_val;
277 int u_len, u_ch;
278 unicode_t uni_char;
279 int (*conv_f)(const unsigned char *, int, wchar_t *);
280
281 if (ocu_max_len <= 0)
282 return 0;
283
284 if (UDF_SB(sb)->s_nls_map)
285 conv_f = UDF_SB(sb)->s_nls_map->char2uni;
286 else
287 conv_f = NULL;
288
289 memset(ocu, 0, ocu_max_len);
290 ocu[0] = 8;
291 max_val = 0xff;
292 u_ch = 1;
293
294 try_again:
295 u_len = 1;
296 for (i = 0; i < str_len; i += len) {
297 /* Name didn't fit? */
298 if (u_len + u_ch > ocu_max_len)
299 return 0;
300 if (conv_f) {
301 wchar_t wchar;
302
303 len = conv_f(&str_i[i], str_len - i, &wchar);
304 if (len > 0)
305 uni_char = wchar;
306 } else {
307 len = utf8_to_utf32(&str_i[i], str_len - i,
308 &uni_char);
309 }
310 /* Invalid character, deal with it */
311 if (len <= 0 || uni_char > UNICODE_MAX) {
312 len = 1;
313 uni_char = '?';
314 }
315
316 if (uni_char > max_val) {
317 unicode_t c;
318
319 if (max_val == 0xff) {
320 max_val = 0xffff;
321 ocu[0] = 0x10;
322 u_ch = 2;
323 goto try_again;
324 }
325 /*
326 * Use UTF-16 encoding for chars outside we
327 * cannot encode directly.
328 */
329 if (u_len + 2 * u_ch > ocu_max_len)
330 return 0;
331
332 uni_char -= PLANE_SIZE;
333 c = SURROGATE_PAIR |
334 ((uni_char >> SURROGATE_CHAR_BITS) &
335 SURROGATE_CHAR_MASK);
336 ocu[u_len++] = (uint8_t)(c >> 8);
337 ocu[u_len++] = (uint8_t)(c & 0xff);
338 uni_char = SURROGATE_PAIR | SURROGATE_LOW |
339 (uni_char & SURROGATE_CHAR_MASK);
340 }
341
342 if (max_val == 0xffff)
343 ocu[u_len++] = (uint8_t)(uni_char >> 8);
344 ocu[u_len++] = (uint8_t)(uni_char & 0xff);
345 }
346
347 return u_len;
348 }
349
350 /*
351 * Convert CS0 dstring to output charset. Warning: This function may truncate
352 * input string if it is too long as it is used for informational strings only
353 * and it is better to truncate the string than to refuse mounting a media.
354 */
355 int udf_dstrCS0toChar(struct super_block *sb, uint8_t *utf_o, int o_len,
356 const uint8_t *ocu_i, int i_len)
357 {
358 int s_len = 0;
359
360 if (i_len > 0) {
361 s_len = ocu_i[i_len - 1];
362 if (s_len >= i_len) {
363 pr_warn("incorrect dstring lengths (%d/%d),"
364 " truncating\n", s_len, i_len);
365 s_len = i_len - 1;
366 /* 2-byte encoding? Need to round properly... */
367 if (ocu_i[0] == 16)
368 s_len -= (s_len - 1) & 2;
369 }
370 }
371
372 return udf_name_from_CS0(sb, utf_o, o_len, ocu_i, s_len, 0);
373 }
374
375 int udf_get_filename(struct super_block *sb, const uint8_t *sname, int slen,
376 uint8_t *dname, int dlen)
377 {
378 int ret;
379
380 if (!slen)
381 return -EIO;
382
383 if (dlen <= 0)
384 return 0;
385
386 ret = udf_name_from_CS0(sb, dname, dlen, sname, slen, 1);
387 /* Zero length filename isn't valid... */
388 if (ret == 0)
389 ret = -EINVAL;
390 return ret;
391 }
392
393 int udf_put_filename(struct super_block *sb, const uint8_t *sname, int slen,
394 uint8_t *dname, int dlen)
395 {
396 return udf_name_to_CS0(sb, dname, dlen, sname, slen);
397 }
398
399
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.