1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Some of the source code in this file came from fs/cifs/cifs_unicode.c
4 *
5 * Copyright (c) International Business Machines Corp., 2000,2009
6 * Modified by Steve French (sfrench@us.ibm.com)
7 * Modified by Namjae Jeon (linkinjeon@kernel.org)
8 */
9#include <linux/fs.h>
10#include <linux/slab.h>
11#include <linux/unaligned.h>
12#include "glob.h"
13#include "unicode.h"
14#include "smb_common.h"
15
16/*
17 * cifs_mapchar() - convert a host-endian char to proper char in codepage
18 * @target: where converted character should be copied
19 * @from: host-endian source string
20 * @cp: codepage to which character should be converted
21 * @mapchar: should character be mapped according to mapchars mount option?
22 *
23 * This function handles the conversion of a single character. It is the
24 * responsibility of the caller to ensure that the target buffer is large
25 * enough to hold the result of the conversion (at least NLS_MAX_CHARSET_SIZE).
26 *
27 * Return: string length after conversion
28 */
29static int
30cifs_mapchar(char *target, const __u16 *from, const struct nls_table *cp,
31 bool mapchar)
32{
33 int len = 1;
34 __u16 src_char;
35
36 src_char = *from;
37
38 if (!mapchar)
39 goto cp_convert;
40
41 /*
42 * BB: Cannot handle remapping UNI_SLASH until all the calls to
43 * build_path_from_dentry are modified, as they use slash as
44 * separator.
45 */
46 switch (src_char) {
47 case UNI_COLON:
48 *target = ':';
49 break;
50 case UNI_ASTERISK:
51 *target = '*';
52 break;
53 case UNI_QUESTION:
54 *target = '?';
55 break;
56 case UNI_PIPE:
57 *target = '|';
58 break;
59 case UNI_GRTRTHAN:
60 *target = '>';
61 break;
62 case UNI_LESSTHAN:
63 *target = '<';
64 break;
65 default:
66 goto cp_convert;
67 }
68
69out:
70 return len;
71
72cp_convert:
73 len = cp->uni2char(src_char, target, NLS_MAX_CHARSET_SIZE);
74 if (len <= 0)
75 goto surrogate_pair;
76
77 goto out;
78
79surrogate_pair:
80 /* convert SURROGATE_PAIR and IVS */
81 if (strcmp(cp->charset, "utf8"))
82 goto unknown;
83 len = utf16s_to_utf8s(pwcs: from, len: 3, endian: UTF16_LITTLE_ENDIAN, s: target, maxlen: 6);
84 if (len <= 0)
85 goto unknown;
86 return len;
87
88unknown:
89 *target = '?';
90 len = 1;
91 goto out;
92}
93
94/*
95 * smb_utf16_bytes() - compute converted string length
96 * @from: pointer to input string
97 * @maxbytes: input string length
98 * @codepage: destination codepage
99 *
100 * Walk a utf16le string and return the number of bytes that the string will
101 * be after being converted to the given charset, not including any null
102 * termination required. Don't walk past maxbytes in the source buffer.
103 *
104 * Return: string length after conversion
105 */
106static int smb_utf16_bytes(const __le16 *from, int maxbytes,
107 const struct nls_table *codepage)
108{
109 int i, j;
110 int charlen, outlen = 0;
111 int maxwords = maxbytes / 2;
112 char tmp[NLS_MAX_CHARSET_SIZE];
113 __u16 ftmp[3];
114
115 for (i = 0; i < maxwords; i++) {
116 ftmp[0] = get_unaligned_le16(p: &from[i]);
117 if (ftmp[0] == 0)
118 break;
119 for (j = 1; j <= 2; j++) {
120 if (i + j < maxwords)
121 ftmp[j] = get_unaligned_le16(p: &from[i + j]);
122 else
123 ftmp[j] = 0;
124 }
125
126 charlen = cifs_mapchar(target: tmp, from: ftmp, cp: codepage, mapchar: 0);
127 if (charlen > 0)
128 outlen += charlen;
129 else
130 outlen++;
131 }
132
133 return outlen;
134}
135
136/*
137 * smb_from_utf16() - convert utf16le string to local charset
138 * @to: destination buffer
139 * @from: source buffer
140 * @tolen: destination buffer size (in bytes)
141 * @fromlen: source buffer size (in bytes)
142 * @codepage: codepage to which characters should be converted
143 * @mapchar: should characters be remapped according to the mapchars option?
144 *
145 * Convert a little-endian utf16le string (as sent by the server) to a string
146 * in the provided codepage. The tolen and fromlen parameters are to ensure
147 * that the code doesn't walk off of the end of the buffer (which is always
148 * a danger if the alignment of the source buffer is off). The destination
149 * string is always properly null terminated and fits in the destination
150 * buffer. Returns the length of the destination string in bytes (including
151 * null terminator).
152 *
153 * Note that some windows versions actually send multiword UTF-16 characters
154 * instead of straight UTF16-2. The linux nls routines however aren't able to
155 * deal with those characters properly. In the event that we get some of
156 * those characters, they won't be translated properly.
157 *
158 * Return: string length after conversion
159 */
160static int smb_from_utf16(char *to, const __le16 *from, int tolen, int fromlen,
161 const struct nls_table *codepage, bool mapchar)
162{
163 int i, j, charlen, safelen;
164 int outlen = 0;
165 int nullsize = nls_nullsize(codepage);
166 int fromwords = fromlen / 2;
167 char tmp[NLS_MAX_CHARSET_SIZE];
168 __u16 ftmp[3]; /* ftmp[3] = 3array x 2bytes = 6bytes UTF-16 */
169
170 /*
171 * because the chars can be of varying widths, we need to take care
172 * not to overflow the destination buffer when we get close to the
173 * end of it. Until we get to this offset, we don't need to check
174 * for overflow however.
175 */
176 safelen = tolen - (NLS_MAX_CHARSET_SIZE + nullsize);
177
178 for (i = 0; i < fromwords; i++) {
179 ftmp[0] = get_unaligned_le16(p: &from[i]);
180 if (ftmp[0] == 0)
181 break;
182 for (j = 1; j <= 2; j++) {
183 if (i + j < fromwords)
184 ftmp[j] = get_unaligned_le16(p: &from[i + j]);
185 else
186 ftmp[j] = 0;
187 }
188
189 /*
190 * check to see if converting this character might make the
191 * conversion bleed into the null terminator
192 */
193 if (outlen >= safelen) {
194 charlen = cifs_mapchar(target: tmp, from: ftmp, cp: codepage, mapchar);
195 if ((outlen + charlen) > (tolen - nullsize))
196 break;
197 }
198
199 /* put converted char into 'to' buffer */
200 charlen = cifs_mapchar(target: &to[outlen], from: ftmp, cp: codepage, mapchar);
201 outlen += charlen;
202
203 /*
204 * charlen (=bytes of UTF-8 for 1 character)
205 * 4bytes UTF-8(surrogate pair) is charlen=4
206 * (4bytes UTF-16 code)
207 * 7-8bytes UTF-8(IVS) is charlen=3+4 or 4+4
208 * (2 UTF-8 pairs divided to 2 UTF-16 pairs)
209 */
210 if (charlen == 4)
211 i++;
212 else if (charlen >= 5)
213 /* 5-6bytes UTF-8 */
214 i += 2;
215 }
216
217 /* properly null-terminate string */
218 for (i = 0; i < nullsize; i++)
219 to[outlen++] = 0;
220
221 return outlen;
222}
223
224/*
225 * smb_strtoUTF16() - Convert character string to unicode string
226 * @to: destination buffer
227 * @from: source buffer
228 * @len: destination buffer size (in bytes)
229 * @codepage: codepage to which characters should be converted
230 *
231 * Return: string length after conversion
232 */
233int smb_strtoUTF16(__le16 *to, const char *from, int len,
234 const struct nls_table *codepage)
235{
236 int charlen;
237 int i;
238 wchar_t wchar_to; /* needed to quiet sparse */
239
240 /* special case for utf8 to handle no plane0 chars */
241 if (!strcmp(codepage->charset, "utf8")) {
242 /*
243 * convert utf8 -> utf16, we assume we have enough space
244 * as caller should have assumed conversion does not overflow
245 * in destination len is length in wchar_t units (16bits)
246 */
247 i = utf8s_to_utf16s(s: from, len, endian: UTF16_LITTLE_ENDIAN,
248 pwcs: (wchar_t *)to, maxlen: len);
249
250 /* if success terminate and exit */
251 if (i >= 0)
252 goto success;
253 /*
254 * if fails fall back to UCS encoding as this
255 * function should not return negative values
256 * currently can fail only if source contains
257 * invalid encoded characters
258 */
259 }
260
261 for (i = 0; len > 0 && *from; i++, from += charlen, len -= charlen) {
262 charlen = codepage->char2uni(from, len, &wchar_to);
263 if (charlen < 1) {
264 /* A question mark */
265 wchar_to = 0x003f;
266 charlen = 1;
267 }
268 put_unaligned_le16(val: wchar_to, p: &to[i]);
269 }
270
271success:
272 put_unaligned_le16(val: 0, p: &to[i]);
273 return i;
274}
275
276/*
277 * smb_strndup_from_utf16() - copy a string from wire format to the local
278 * codepage
279 * @src: source string
280 * @maxlen: don't walk past this many bytes in the source string
281 * @is_unicode: is this a unicode string?
282 * @codepage: destination codepage
283 *
284 * Take a string given by the server, convert it to the local codepage and
285 * put it in a new buffer. Returns a pointer to the new string or NULL on
286 * error.
287 *
288 * Return: destination string buffer or error ptr
289 */
290char *smb_strndup_from_utf16(const char *src, const int maxlen,
291 const bool is_unicode,
292 const struct nls_table *codepage)
293{
294 int len, ret;
295 char *dst;
296
297 if (is_unicode) {
298 len = smb_utf16_bytes(from: (__le16 *)src, maxbytes: maxlen, codepage);
299 len += nls_nullsize(codepage);
300 dst = kmalloc(len, KSMBD_DEFAULT_GFP);
301 if (!dst)
302 return ERR_PTR(error: -ENOMEM);
303 ret = smb_from_utf16(to: dst, from: (__le16 *)src, tolen: len, fromlen: maxlen, codepage,
304 mapchar: false);
305 if (ret < 0) {
306 kfree(objp: dst);
307 return ERR_PTR(error: -EINVAL);
308 }
309 } else {
310 len = strnlen(p: src, maxlen);
311 len++;
312 dst = kmalloc(len, KSMBD_DEFAULT_GFP);
313 if (!dst)
314 return ERR_PTR(error: -ENOMEM);
315 strscpy(dst, src, len);
316 }
317
318 return dst;
319}
320
321/*
322 * Convert 16 bit Unicode pathname to wire format from string in current code
323 * page. Conversion may involve remapping up the six characters that are
324 * only legal in POSIX-like OS (if they are present in the string). Path
325 * names are little endian 16 bit Unicode on the wire
326 */
327/*
328 * smbConvertToUTF16() - convert string from local charset to utf16
329 * @target: destination buffer
330 * @source: source buffer
331 * @srclen: source buffer size (in bytes)
332 * @cp: codepage to which characters should be converted
333 * @mapchar: should characters be remapped according to the mapchars option?
334 *
335 * Convert 16 bit Unicode pathname to wire format from string in current code
336 * page. Conversion may involve remapping up the six characters that are
337 * only legal in POSIX-like OS (if they are present in the string). Path
338 * names are little endian 16 bit Unicode on the wire
339 *
340 * Return: char length after conversion
341 */
342int smbConvertToUTF16(__le16 *target, const char *source, int srclen,
343 const struct nls_table *cp, int mapchars)
344{
345 int i, j, charlen;
346 char src_char;
347 __le16 dst_char;
348 wchar_t tmp;
349 wchar_t wchar_to[6]; /* UTF-16 */
350 int ret;
351 unicode_t u;
352
353 if (!mapchars)
354 return smb_strtoUTF16(to: target, from: source, len: srclen, codepage: cp);
355
356 for (i = 0, j = 0; i < srclen; j++) {
357 src_char = source[i];
358 charlen = 1;
359 switch (src_char) {
360 case 0:
361 put_unaligned(0, &target[j]);
362 return j;
363 case ':':
364 dst_char = cpu_to_le16(UNI_COLON);
365 break;
366 case '*':
367 dst_char = cpu_to_le16(UNI_ASTERISK);
368 break;
369 case '?':
370 dst_char = cpu_to_le16(UNI_QUESTION);
371 break;
372 case '<':
373 dst_char = cpu_to_le16(UNI_LESSTHAN);
374 break;
375 case '>':
376 dst_char = cpu_to_le16(UNI_GRTRTHAN);
377 break;
378 case '|':
379 dst_char = cpu_to_le16(UNI_PIPE);
380 break;
381 /*
382 * FIXME: We can not handle remapping backslash (UNI_SLASH)
383 * until all the calls to build_path_from_dentry are modified,
384 * as they use backslash as separator.
385 */
386 default:
387 charlen = cp->char2uni(source + i, srclen - i, &tmp);
388 dst_char = cpu_to_le16(tmp);
389
390 /*
391 * if no match, use question mark, which at least in
392 * some cases serves as wild card
393 */
394 if (charlen > 0)
395 goto ctoUTF16;
396
397 /* convert SURROGATE_PAIR */
398 if (strcmp(cp->charset, "utf8"))
399 goto unknown;
400 if (*(source + i) & 0x80) {
401 charlen = utf8_to_utf32(s: source + i, len: 6, pu: &u);
402 if (charlen < 0)
403 goto unknown;
404 } else
405 goto unknown;
406 ret = utf8s_to_utf16s(s: source + i, len: charlen,
407 endian: UTF16_LITTLE_ENDIAN,
408 pwcs: wchar_to, maxlen: 6);
409 if (ret < 0)
410 goto unknown;
411
412 i += charlen;
413 dst_char = cpu_to_le16(*wchar_to);
414 if (charlen <= 3)
415 /* 1-3bytes UTF-8 to 2bytes UTF-16 */
416 put_unaligned(dst_char, &target[j]);
417 else if (charlen == 4) {
418 /*
419 * 4bytes UTF-8(surrogate pair) to 4bytes UTF-16
420 * 7-8bytes UTF-8(IVS) divided to 2 UTF-16
421 * (charlen=3+4 or 4+4)
422 */
423 put_unaligned(dst_char, &target[j]);
424 dst_char = cpu_to_le16(*(wchar_to + 1));
425 j++;
426 put_unaligned(dst_char, &target[j]);
427 } else if (charlen >= 5) {
428 /* 5-6bytes UTF-8 to 6bytes UTF-16 */
429 put_unaligned(dst_char, &target[j]);
430 dst_char = cpu_to_le16(*(wchar_to + 1));
431 j++;
432 put_unaligned(dst_char, &target[j]);
433 dst_char = cpu_to_le16(*(wchar_to + 2));
434 j++;
435 put_unaligned(dst_char, &target[j]);
436 }
437 continue;
438
439unknown:
440 dst_char = cpu_to_le16(0x003f);
441 charlen = 1;
442 }
443
444ctoUTF16:
445 /*
446 * character may take more than one byte in the source string,
447 * but will take exactly two bytes in the target string
448 */
449 i += charlen;
450 put_unaligned(dst_char, &target[j]);
451 }
452
453 return j;
454}
455

source code of linux/fs/smb/server/unicode.c