fs/udf/unicode.c

   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