xref: /openbmc/linux/fs/smb/client/reparse.c (revision 4a44bcb7)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (c) 2024 Paulo Alcantara <pc@manguebit.com>
4  */
5 
6 #include <linux/fs.h>
7 #include <linux/stat.h>
8 #include <linux/slab.h>
9 #include "cifsglob.h"
10 #include "smb2proto.h"
11 #include "cifsproto.h"
12 #include "cifs_unicode.h"
13 #include "cifs_debug.h"
14 #include "fs_context.h"
15 #include "reparse.h"
16 
17 static int detect_directory_symlink_target(struct cifs_sb_info *cifs_sb,
18 					   const unsigned int xid,
19 					   const char *full_path,
20 					   const char *symname,
21 					   bool *directory);
22 
23 int smb2_create_reparse_symlink(const unsigned int xid, struct inode *inode,
24 				struct dentry *dentry, struct cifs_tcon *tcon,
25 				const char *full_path, const char *symname)
26 {
27 	struct reparse_symlink_data_buffer *buf = NULL;
28 	struct cifs_open_info_data data;
29 	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
30 	struct inode *new;
31 	struct kvec iov;
32 	__le16 *path;
33 	bool directory;
34 	char *sym, sep = CIFS_DIR_SEP(cifs_sb);
35 	u16 len, plen;
36 	int rc = 0;
37 
38 	if (strlen(symname) > REPARSE_SYM_PATH_MAX)
39 		return -ENAMETOOLONG;
40 
41 	sym = kstrdup(symname, GFP_KERNEL);
42 	if (!sym)
43 		return -ENOMEM;
44 
45 	data = (struct cifs_open_info_data) {
46 		.reparse_point = true,
47 		.reparse = { .tag = IO_REPARSE_TAG_SYMLINK, },
48 		.symlink_target = sym,
49 	};
50 
51 	convert_delimiter(sym, sep);
52 	path = cifs_convert_path_to_utf16(sym, cifs_sb);
53 	if (!path) {
54 		rc = -ENOMEM;
55 		goto out;
56 	}
57 
58 	/*
59 	 * SMB distinguish between symlink to directory and symlink to file.
60 	 * They cannot be exchanged (symlink of file type which points to
61 	 * directory cannot be resolved and vice-versa). Try to detect if
62 	 * the symlink target could be a directory or not. When detection
63 	 * fails then treat symlink as a file (non-directory) symlink.
64 	 */
65 	directory = false;
66 	rc = detect_directory_symlink_target(cifs_sb, xid, full_path, symname, &directory);
67 	if (rc < 0)
68 		goto out;
69 
70 	plen = 2 * UniStrnlen((wchar_t *)path, REPARSE_SYM_PATH_MAX);
71 	len = sizeof(*buf) + plen * 2;
72 	buf = kzalloc(len, GFP_KERNEL);
73 	if (!buf) {
74 		rc = -ENOMEM;
75 		goto out;
76 	}
77 
78 	buf->ReparseTag = cpu_to_le32(IO_REPARSE_TAG_SYMLINK);
79 	buf->ReparseDataLength = cpu_to_le16(len - sizeof(struct reparse_data_buffer));
80 	buf->SubstituteNameOffset = cpu_to_le16(plen);
81 	buf->SubstituteNameLength = cpu_to_le16(plen);
82 	memcpy(&buf->PathBuffer[plen], path, plen);
83 	buf->PrintNameOffset = 0;
84 	buf->PrintNameLength = cpu_to_le16(plen);
85 	memcpy(buf->PathBuffer, path, plen);
86 	buf->Flags = cpu_to_le32(*symname != '/' ? SYMLINK_FLAG_RELATIVE : 0);
87 	if (*sym != sep)
88 		buf->Flags = cpu_to_le32(SYMLINK_FLAG_RELATIVE);
89 
90 	convert_delimiter(sym, '/');
91 	iov.iov_base = buf;
92 	iov.iov_len = len;
93 	new = smb2_get_reparse_inode(&data, inode->i_sb, xid,
94 				     tcon, full_path, directory,
95 				     &iov, NULL);
96 	if (!IS_ERR(new))
97 		d_instantiate(dentry, new);
98 	else
99 		rc = PTR_ERR(new);
100 out:
101 	kfree(path);
102 	cifs_free_open_info(&data);
103 	kfree(buf);
104 	return rc;
105 }
106 
107 static int detect_directory_symlink_target(struct cifs_sb_info *cifs_sb,
108 					   const unsigned int xid,
109 					   const char *full_path,
110 					   const char *symname,
111 					   bool *directory)
112 {
113 	char sep = CIFS_DIR_SEP(cifs_sb);
114 	struct cifs_open_parms oparms;
115 	struct tcon_link *tlink;
116 	struct cifs_tcon *tcon;
117 	const char *basename;
118 	struct cifs_fid fid;
119 	char *resolved_path;
120 	int full_path_len;
121 	int basename_len;
122 	int symname_len;
123 	char *path_sep;
124 	__u32 oplock;
125 	int open_rc;
126 
127 	/*
128 	 * First do some simple check. If the original Linux symlink target ends
129 	 * with slash, or last path component is dot or dot-dot then it is for
130 	 * sure symlink to the directory.
131 	 */
132 	basename = kbasename(symname);
133 	basename_len = strlen(basename);
134 	if (basename_len == 0 || /* symname ends with slash */
135 	    (basename_len == 1 && basename[0] == '.') || /* last component is "." */
136 	    (basename_len == 2 && basename[0] == '.' && basename[1] == '.')) { /* or ".." */
137 		*directory = true;
138 		return 0;
139 	}
140 
141 	/*
142 	 * For absolute symlinks it is not possible to determinate
143 	 * if it should point to directory or file.
144 	 */
145 	if (symname[0] == '/') {
146 		cifs_dbg(FYI,
147 			 "%s: cannot determinate if the symlink target path '%s' "
148 			 "is directory or not, creating '%s' as file symlink\n",
149 			 __func__, symname, full_path);
150 		return 0;
151 	}
152 
153 	/*
154 	 * If it was not detected as directory yet and the symlink is relative
155 	 * then try to resolve the path on the SMB server, check if the path
156 	 * exists and determinate if it is a directory or not.
157 	 */
158 
159 	full_path_len = strlen(full_path);
160 	symname_len = strlen(symname);
161 
162 	tlink = cifs_sb_tlink(cifs_sb);
163 	if (IS_ERR(tlink))
164 		return PTR_ERR(tlink);
165 
166 	resolved_path = kzalloc(full_path_len + symname_len + 1, GFP_KERNEL);
167 	if (!resolved_path) {
168 		cifs_put_tlink(tlink);
169 		return -ENOMEM;
170 	}
171 
172 	/*
173 	 * Compose the resolved SMB symlink path from the SMB full path
174 	 * and Linux target symlink path.
175 	 */
176 	memcpy(resolved_path, full_path, full_path_len+1);
177 	path_sep = strrchr(resolved_path, sep);
178 	if (path_sep)
179 		path_sep++;
180 	else
181 		path_sep = resolved_path;
182 	memcpy(path_sep, symname, symname_len+1);
183 	if (sep == '\\')
184 		convert_delimiter(path_sep, sep);
185 
186 	tcon = tlink_tcon(tlink);
187 	oparms = CIFS_OPARMS(cifs_sb, tcon, resolved_path,
188 			     FILE_READ_ATTRIBUTES, FILE_OPEN, 0, ACL_NO_MODE);
189 	oparms.fid = &fid;
190 
191 	/* Try to open as a directory (NOT_FILE) */
192 	oplock = 0;
193 	oparms.create_options = cifs_create_options(cifs_sb,
194 						    CREATE_NOT_FILE | OPEN_REPARSE_POINT);
195 	open_rc = tcon->ses->server->ops->open(xid, &oparms, &oplock, NULL);
196 	if (open_rc == 0) {
197 		/* Successful open means that the target path is definitely a directory. */
198 		*directory = true;
199 		tcon->ses->server->ops->close(xid, tcon, &fid);
200 	} else if (open_rc == -ENOTDIR) {
201 		/* -ENOTDIR means that the target path is definitely a file. */
202 		*directory = false;
203 	} else if (open_rc == -ENOENT) {
204 		/* -ENOENT means that the target path does not exist. */
205 		cifs_dbg(FYI,
206 			 "%s: symlink target path '%s' does not exist, "
207 			 "creating '%s' as file symlink\n",
208 			 __func__, symname, full_path);
209 	} else {
210 		/* Try to open as a file (NOT_DIR) */
211 		oplock = 0;
212 		oparms.create_options = cifs_create_options(cifs_sb,
213 							    CREATE_NOT_DIR | OPEN_REPARSE_POINT);
214 		open_rc = tcon->ses->server->ops->open(xid, &oparms, &oplock, NULL);
215 		if (open_rc == 0) {
216 			/* Successful open means that the target path is definitely a file. */
217 			*directory = false;
218 			tcon->ses->server->ops->close(xid, tcon, &fid);
219 		} else if (open_rc == -EISDIR) {
220 			/* -EISDIR means that the target path is definitely a directory. */
221 			*directory = true;
222 		} else {
223 			/*
224 			 * This code branch is called when we do not have a permission to
225 			 * open the resolved_path or some other client/process denied
226 			 * opening the resolved_path.
227 			 *
228 			 * TODO: Try to use ops->query_dir_first on the parent directory
229 			 * of resolved_path, search for basename of resolved_path and
230 			 * check if the ATTR_DIRECTORY is set in fi.Attributes. In some
231 			 * case this could work also when opening of the path is denied.
232 			 */
233 			cifs_dbg(FYI,
234 				 "%s: cannot determinate if the symlink target path '%s' "
235 				 "is directory or not, creating '%s' as file symlink\n",
236 				 __func__, symname, full_path);
237 		}
238 	}
239 
240 	kfree(resolved_path);
241 	cifs_put_tlink(tlink);
242 	return 0;
243 }
244 
245 static int nfs_set_reparse_buf(struct reparse_posix_data *buf,
246 			       mode_t mode, dev_t dev,
247 			       struct kvec *iov)
248 {
249 	u64 type;
250 	u16 len, dlen;
251 
252 	len = sizeof(*buf);
253 
254 	switch ((type = reparse_mode_nfs_type(mode))) {
255 	case NFS_SPECFILE_BLK:
256 	case NFS_SPECFILE_CHR:
257 		dlen = sizeof(__le64);
258 		break;
259 	case NFS_SPECFILE_FIFO:
260 	case NFS_SPECFILE_SOCK:
261 		dlen = 0;
262 		break;
263 	default:
264 		return -EOPNOTSUPP;
265 	}
266 
267 	buf->ReparseTag = cpu_to_le32(IO_REPARSE_TAG_NFS);
268 	buf->Reserved = 0;
269 	buf->InodeType = cpu_to_le64(type);
270 	buf->ReparseDataLength = cpu_to_le16(len + dlen -
271 					     sizeof(struct reparse_data_buffer));
272 	*(__le64 *)buf->DataBuffer = cpu_to_le64(((u64)MINOR(dev) << 32) |
273 						 MAJOR(dev));
274 	iov->iov_base = buf;
275 	iov->iov_len = len + dlen;
276 	return 0;
277 }
278 
279 static int mknod_nfs(unsigned int xid, struct inode *inode,
280 		     struct dentry *dentry, struct cifs_tcon *tcon,
281 		     const char *full_path, umode_t mode, dev_t dev)
282 {
283 	struct cifs_open_info_data data;
284 	struct reparse_posix_data *p;
285 	struct inode *new;
286 	struct kvec iov;
287 	__u8 buf[sizeof(*p) + sizeof(__le64)];
288 	int rc;
289 
290 	p = (struct reparse_posix_data *)buf;
291 	rc = nfs_set_reparse_buf(p, mode, dev, &iov);
292 	if (rc)
293 		return rc;
294 
295 	data = (struct cifs_open_info_data) {
296 		.reparse_point = true,
297 		.reparse = { .tag = IO_REPARSE_TAG_NFS, .posix = p, },
298 	};
299 
300 	new = smb2_get_reparse_inode(&data, inode->i_sb, xid,
301 				     tcon, full_path, false, &iov, NULL);
302 	if (!IS_ERR(new))
303 		d_instantiate(dentry, new);
304 	else
305 		rc = PTR_ERR(new);
306 	cifs_free_open_info(&data);
307 	return rc;
308 }
309 
310 static int wsl_set_reparse_buf(struct reparse_data_buffer *buf,
311 			       mode_t mode, struct kvec *iov)
312 {
313 	u32 tag;
314 
315 	switch ((tag = reparse_mode_wsl_tag(mode))) {
316 	case IO_REPARSE_TAG_LX_BLK:
317 	case IO_REPARSE_TAG_LX_CHR:
318 	case IO_REPARSE_TAG_LX_FIFO:
319 	case IO_REPARSE_TAG_AF_UNIX:
320 		break;
321 	default:
322 		return -EOPNOTSUPP;
323 	}
324 
325 	buf->ReparseTag = cpu_to_le32(tag);
326 	buf->Reserved = 0;
327 	buf->ReparseDataLength = 0;
328 	iov->iov_base = buf;
329 	iov->iov_len = sizeof(*buf);
330 	return 0;
331 }
332 
333 static struct smb2_create_ea_ctx *ea_create_context(u32 dlen, size_t *cc_len)
334 {
335 	struct smb2_create_ea_ctx *cc;
336 
337 	*cc_len = round_up(sizeof(*cc) + dlen, 8);
338 	cc = kzalloc(*cc_len, GFP_KERNEL);
339 	if (!cc)
340 		return ERR_PTR(-ENOMEM);
341 
342 	cc->ctx.NameOffset = cpu_to_le16(offsetof(struct smb2_create_ea_ctx,
343 						  name));
344 	cc->ctx.NameLength = cpu_to_le16(4);
345 	memcpy(cc->name, SMB2_CREATE_EA_BUFFER, strlen(SMB2_CREATE_EA_BUFFER));
346 	cc->ctx.DataOffset = cpu_to_le16(offsetof(struct smb2_create_ea_ctx, ea));
347 	cc->ctx.DataLength = cpu_to_le32(dlen);
348 	return cc;
349 }
350 
351 struct wsl_xattr {
352 	const char	*name;
353 	__le64		value;
354 	u16		size;
355 	u32		next;
356 };
357 
358 static int wsl_set_xattrs(struct inode *inode, umode_t _mode,
359 			  dev_t _dev, struct kvec *iov)
360 {
361 	struct smb2_file_full_ea_info *ea;
362 	struct smb2_create_ea_ctx *cc;
363 	struct smb3_fs_context *ctx = CIFS_SB(inode->i_sb)->ctx;
364 	__le64 uid = cpu_to_le64(from_kuid(current_user_ns(), ctx->linux_uid));
365 	__le64 gid = cpu_to_le64(from_kgid(current_user_ns(), ctx->linux_gid));
366 	__le64 dev = cpu_to_le64(((u64)MINOR(_dev) << 32) | MAJOR(_dev));
367 	__le64 mode = cpu_to_le64(_mode);
368 	struct wsl_xattr xattrs[] = {
369 		{ .name = SMB2_WSL_XATTR_UID,  .value = uid,  .size = SMB2_WSL_XATTR_UID_SIZE, },
370 		{ .name = SMB2_WSL_XATTR_GID,  .value = gid,  .size = SMB2_WSL_XATTR_GID_SIZE, },
371 		{ .name = SMB2_WSL_XATTR_MODE, .value = mode, .size = SMB2_WSL_XATTR_MODE_SIZE, },
372 		{ .name = SMB2_WSL_XATTR_DEV,  .value = dev, .size = SMB2_WSL_XATTR_DEV_SIZE, },
373 	};
374 	size_t cc_len;
375 	u32 dlen = 0, next = 0;
376 	int i, num_xattrs;
377 	u8 name_size = SMB2_WSL_XATTR_NAME_LEN + 1;
378 
379 	memset(iov, 0, sizeof(*iov));
380 
381 	/* Exclude $LXDEV xattr for sockets and fifos */
382 	if (S_ISSOCK(_mode) || S_ISFIFO(_mode))
383 		num_xattrs = ARRAY_SIZE(xattrs) - 1;
384 	else
385 		num_xattrs = ARRAY_SIZE(xattrs);
386 
387 	for (i = 0; i < num_xattrs; i++) {
388 		xattrs[i].next = ALIGN(sizeof(*ea) + name_size +
389 				       xattrs[i].size, 4);
390 		dlen += xattrs[i].next;
391 	}
392 
393 	cc = ea_create_context(dlen, &cc_len);
394 	if (IS_ERR(cc))
395 		return PTR_ERR(cc);
396 
397 	ea = &cc->ea;
398 	for (i = 0; i < num_xattrs; i++) {
399 		ea = (void *)((u8 *)ea + next);
400 		next = xattrs[i].next;
401 		ea->next_entry_offset = cpu_to_le32(next);
402 
403 		ea->ea_name_length = name_size - 1;
404 		ea->ea_value_length = cpu_to_le16(xattrs[i].size);
405 		memcpy(ea->ea_data, xattrs[i].name, name_size);
406 		memcpy(&ea->ea_data[name_size],
407 		       &xattrs[i].value, xattrs[i].size);
408 	}
409 	ea->next_entry_offset = 0;
410 
411 	iov->iov_base = cc;
412 	iov->iov_len = cc_len;
413 	return 0;
414 }
415 
416 static int mknod_wsl(unsigned int xid, struct inode *inode,
417 		     struct dentry *dentry, struct cifs_tcon *tcon,
418 		     const char *full_path, umode_t mode, dev_t dev)
419 {
420 	struct cifs_open_info_data data;
421 	struct reparse_data_buffer buf;
422 	struct smb2_create_ea_ctx *cc;
423 	struct inode *new;
424 	unsigned int len;
425 	struct kvec reparse_iov, xattr_iov;
426 	int rc;
427 
428 	rc = wsl_set_reparse_buf(&buf, mode, &reparse_iov);
429 	if (rc)
430 		return rc;
431 
432 	rc = wsl_set_xattrs(inode, mode, dev, &xattr_iov);
433 	if (rc)
434 		return rc;
435 
436 	data = (struct cifs_open_info_data) {
437 		.reparse_point = true,
438 		.reparse = { .tag = le32_to_cpu(buf.ReparseTag), .buf = &buf, },
439 	};
440 
441 	cc = xattr_iov.iov_base;
442 	len = le32_to_cpu(cc->ctx.DataLength);
443 	memcpy(data.wsl.eas, &cc->ea, len);
444 	data.wsl.eas_len = len;
445 
446 	new = smb2_get_reparse_inode(&data, inode->i_sb,
447 				     xid, tcon, full_path, false,
448 				     &reparse_iov, &xattr_iov);
449 	if (!IS_ERR(new))
450 		d_instantiate(dentry, new);
451 	else
452 		rc = PTR_ERR(new);
453 	cifs_free_open_info(&data);
454 	kfree(xattr_iov.iov_base);
455 	return rc;
456 }
457 
458 int smb2_mknod_reparse(unsigned int xid, struct inode *inode,
459 		       struct dentry *dentry, struct cifs_tcon *tcon,
460 		       const char *full_path, umode_t mode, dev_t dev)
461 {
462 	struct smb3_fs_context *ctx = CIFS_SB(inode->i_sb)->ctx;
463 	int rc = -EOPNOTSUPP;
464 
465 	switch (ctx->reparse_type) {
466 	case CIFS_REPARSE_TYPE_NFS:
467 		rc = mknod_nfs(xid, inode, dentry, tcon, full_path, mode, dev);
468 		break;
469 	case CIFS_REPARSE_TYPE_WSL:
470 		rc = mknod_wsl(xid, inode, dentry, tcon, full_path, mode, dev);
471 		break;
472 	}
473 	return rc;
474 }
475 
476 /* See MS-FSCC 2.1.2.6 for the 'NFS' style reparse tags */
477 static int parse_reparse_posix(struct reparse_posix_data *buf,
478 			       struct cifs_sb_info *cifs_sb,
479 			       struct cifs_open_info_data *data)
480 {
481 	unsigned int len;
482 	u64 type;
483 
484 	len = le16_to_cpu(buf->ReparseDataLength);
485 	if (len < sizeof(buf->InodeType)) {
486 		cifs_dbg(VFS, "srv returned malformed nfs buffer\n");
487 		return -EIO;
488 	}
489 
490 	len -= sizeof(buf->InodeType);
491 
492 	switch ((type = le64_to_cpu(buf->InodeType))) {
493 	case NFS_SPECFILE_LNK:
494 		if (len == 0 || (len % 2)) {
495 			cifs_dbg(VFS, "srv returned malformed nfs symlink buffer\n");
496 			return -EIO;
497 		}
498 		/*
499 		 * Check that buffer does not contain UTF-16 null codepoint
500 		 * because Linux cannot process symlink with null byte.
501 		 */
502 		if (UniStrnlen((wchar_t *)buf->DataBuffer, len/2) != len/2) {
503 			cifs_dbg(VFS, "srv returned null byte in nfs symlink target location\n");
504 			return -EIO;
505 		}
506 		data->symlink_target = cifs_strndup_from_utf16(buf->DataBuffer,
507 							       len, true,
508 							       cifs_sb->local_nls);
509 		if (!data->symlink_target)
510 			return -ENOMEM;
511 		cifs_dbg(FYI, "%s: target path: %s\n",
512 			 __func__, data->symlink_target);
513 		break;
514 	case NFS_SPECFILE_CHR:
515 	case NFS_SPECFILE_BLK:
516 		/* DataBuffer for block and char devices contains two 32-bit numbers */
517 		if (len != 8) {
518 			cifs_dbg(VFS, "srv returned malformed nfs buffer for type: 0x%llx\n", type);
519 			return -EIO;
520 		}
521 		break;
522 	case NFS_SPECFILE_FIFO:
523 	case NFS_SPECFILE_SOCK:
524 		/* DataBuffer for fifos and sockets is empty */
525 		if (len != 0) {
526 			cifs_dbg(VFS, "srv returned malformed nfs buffer for type: 0x%llx\n", type);
527 			return -EIO;
528 		}
529 		break;
530 	default:
531 		cifs_dbg(VFS, "%s: unhandled inode type: 0x%llx\n",
532 			 __func__, type);
533 		return -EOPNOTSUPP;
534 	}
535 	return 0;
536 }
537 
538 int smb2_parse_native_symlink(char **target, const char *buf, unsigned int len,
539 			      bool unicode, bool relative,
540 			      const char *full_path,
541 			      struct cifs_sb_info *cifs_sb)
542 {
543 	char sep = CIFS_DIR_SEP(cifs_sb);
544 	char *linux_target = NULL;
545 	char *smb_target = NULL;
546 	int levels;
547 	int rc;
548 	int i;
549 
550 	smb_target = cifs_strndup_from_utf16(buf, len, unicode, cifs_sb->local_nls);
551 	if (!smb_target) {
552 		rc = -ENOMEM;
553 		goto out;
554 	}
555 
556 	if (smb_target[0] == sep && relative) {
557 		/*
558 		 * This is a relative SMB symlink from the top of the share,
559 		 * which is the top level directory of the Linux mount point.
560 		 * Linux does not support such relative symlinks, so convert
561 		 * it to the relative symlink from the current directory.
562 		 * full_path is the SMB path to the symlink (from which is
563 		 * extracted current directory) and smb_target is the SMB path
564 		 * where symlink points, therefore full_path must always be on
565 		 * the SMB share.
566 		 */
567 		int smb_target_len = strlen(smb_target)+1;
568 		levels = 0;
569 		for (i = 1; full_path[i]; i++) { /* i=1 to skip leading sep */
570 			if (full_path[i] == sep)
571 				levels++;
572 		}
573 		linux_target = kmalloc(levels*3 + smb_target_len, GFP_KERNEL);
574 		if (!linux_target) {
575 			rc = -ENOMEM;
576 			goto out;
577 		}
578 		for (i = 0; i < levels; i++) {
579 			linux_target[i*3 + 0] = '.';
580 			linux_target[i*3 + 1] = '.';
581 			linux_target[i*3 + 2] = sep;
582 		}
583 		memcpy(linux_target + levels*3, smb_target+1, smb_target_len); /* +1 to skip leading sep */
584 	} else {
585 		linux_target = smb_target;
586 		smb_target = NULL;
587 	}
588 
589 	if (sep == '\\')
590 		convert_delimiter(linux_target, '/');
591 
592 	rc = 0;
593 	*target = linux_target;
594 
595 	cifs_dbg(FYI, "%s: symlink target: %s\n", __func__, *target);
596 
597 out:
598 	if (rc != 0)
599 		kfree(linux_target);
600 	kfree(smb_target);
601 	return rc;
602 }
603 
604 static int parse_reparse_symlink(struct reparse_symlink_data_buffer *sym,
605 				 u32 plen, bool unicode,
606 				 struct cifs_sb_info *cifs_sb,
607 				 const char *full_path,
608 				 struct cifs_open_info_data *data)
609 {
610 	unsigned int len;
611 	unsigned int offs;
612 
613 	/* We handle Symbolic Link reparse tag here. See: MS-FSCC 2.1.2.4 */
614 
615 	offs = le16_to_cpu(sym->SubstituteNameOffset);
616 	len = le16_to_cpu(sym->SubstituteNameLength);
617 	if (offs + 20 > plen || offs + len + 20 > plen) {
618 		cifs_dbg(VFS, "srv returned malformed symlink buffer\n");
619 		return -EIO;
620 	}
621 
622 	return smb2_parse_native_symlink(&data->symlink_target,
623 					 sym->PathBuffer + offs,
624 					 len,
625 					 unicode,
626 					 le32_to_cpu(sym->Flags) & SYMLINK_FLAG_RELATIVE,
627 					 full_path,
628 					 cifs_sb);
629 }
630 
631 int parse_reparse_point(struct reparse_data_buffer *buf,
632 			u32 plen, struct cifs_sb_info *cifs_sb,
633 			const char *full_path,
634 			bool unicode, struct cifs_open_info_data *data)
635 {
636 	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
637 
638 	data->reparse.buf = buf;
639 
640 	/* See MS-FSCC 2.1.2 */
641 	switch (le32_to_cpu(buf->ReparseTag)) {
642 	case IO_REPARSE_TAG_NFS:
643 		return parse_reparse_posix((struct reparse_posix_data *)buf,
644 					   cifs_sb, data);
645 	case IO_REPARSE_TAG_SYMLINK:
646 		return parse_reparse_symlink(
647 			(struct reparse_symlink_data_buffer *)buf,
648 			plen, unicode, cifs_sb, full_path, data);
649 	case IO_REPARSE_TAG_LX_SYMLINK:
650 	case IO_REPARSE_TAG_AF_UNIX:
651 	case IO_REPARSE_TAG_LX_FIFO:
652 	case IO_REPARSE_TAG_LX_CHR:
653 	case IO_REPARSE_TAG_LX_BLK:
654 		break;
655 	default:
656 		cifs_tcon_dbg(VFS | ONCE, "unhandled reparse tag: 0x%08x\n",
657 			      le32_to_cpu(buf->ReparseTag));
658 		break;
659 	}
660 	return 0;
661 }
662 
663 int smb2_parse_reparse_point(struct cifs_sb_info *cifs_sb,
664 			     const char *full_path,
665 			     struct kvec *rsp_iov,
666 			     struct cifs_open_info_data *data)
667 {
668 	struct reparse_data_buffer *buf;
669 	struct smb2_ioctl_rsp *io = rsp_iov->iov_base;
670 	u32 plen = le32_to_cpu(io->OutputCount);
671 
672 	buf = (struct reparse_data_buffer *)((u8 *)io +
673 					     le32_to_cpu(io->OutputOffset));
674 	return parse_reparse_point(buf, plen, cifs_sb, full_path, true, data);
675 }
676 
677 static void wsl_to_fattr(struct cifs_open_info_data *data,
678 			 struct cifs_sb_info *cifs_sb,
679 			 u32 tag, struct cifs_fattr *fattr)
680 {
681 	struct smb2_file_full_ea_info *ea;
682 	u32 next = 0;
683 
684 	switch (tag) {
685 	case IO_REPARSE_TAG_LX_SYMLINK:
686 		fattr->cf_mode |= S_IFLNK;
687 		break;
688 	case IO_REPARSE_TAG_LX_FIFO:
689 		fattr->cf_mode |= S_IFIFO;
690 		break;
691 	case IO_REPARSE_TAG_AF_UNIX:
692 		fattr->cf_mode |= S_IFSOCK;
693 		break;
694 	case IO_REPARSE_TAG_LX_CHR:
695 		fattr->cf_mode |= S_IFCHR;
696 		break;
697 	case IO_REPARSE_TAG_LX_BLK:
698 		fattr->cf_mode |= S_IFBLK;
699 		break;
700 	}
701 
702 	if (!data->wsl.eas_len)
703 		goto out;
704 
705 	ea = (struct smb2_file_full_ea_info *)data->wsl.eas;
706 	do {
707 		const char *name;
708 		void *v;
709 		u8 nlen;
710 
711 		ea = (void *)((u8 *)ea + next);
712 		next = le32_to_cpu(ea->next_entry_offset);
713 		if (!le16_to_cpu(ea->ea_value_length))
714 			continue;
715 
716 		name = ea->ea_data;
717 		nlen = ea->ea_name_length;
718 		v = (void *)((u8 *)ea->ea_data + ea->ea_name_length + 1);
719 
720 		if (!strncmp(name, SMB2_WSL_XATTR_UID, nlen))
721 			fattr->cf_uid = wsl_make_kuid(cifs_sb, v);
722 		else if (!strncmp(name, SMB2_WSL_XATTR_GID, nlen))
723 			fattr->cf_gid = wsl_make_kgid(cifs_sb, v);
724 		else if (!strncmp(name, SMB2_WSL_XATTR_MODE, nlen))
725 			fattr->cf_mode = (umode_t)le32_to_cpu(*(__le32 *)v);
726 		else if (!strncmp(name, SMB2_WSL_XATTR_DEV, nlen))
727 			fattr->cf_rdev = reparse_mkdev(v);
728 	} while (next);
729 out:
730 	fattr->cf_dtype = S_DT(fattr->cf_mode);
731 }
732 
733 bool cifs_reparse_point_to_fattr(struct cifs_sb_info *cifs_sb,
734 				 struct cifs_fattr *fattr,
735 				 struct cifs_open_info_data *data)
736 {
737 	struct reparse_posix_data *buf = data->reparse.posix;
738 	u32 tag = data->reparse.tag;
739 
740 	if (tag == IO_REPARSE_TAG_NFS && buf) {
741 		if (le16_to_cpu(buf->ReparseDataLength) < sizeof(buf->InodeType))
742 			return false;
743 		switch (le64_to_cpu(buf->InodeType)) {
744 		case NFS_SPECFILE_CHR:
745 			if (le16_to_cpu(buf->ReparseDataLength) != sizeof(buf->InodeType) + 8)
746 				return false;
747 			fattr->cf_mode |= S_IFCHR;
748 			fattr->cf_rdev = reparse_mkdev(buf->DataBuffer);
749 			break;
750 		case NFS_SPECFILE_BLK:
751 			if (le16_to_cpu(buf->ReparseDataLength) != sizeof(buf->InodeType) + 8)
752 				return false;
753 			fattr->cf_mode |= S_IFBLK;
754 			fattr->cf_rdev = reparse_mkdev(buf->DataBuffer);
755 			break;
756 		case NFS_SPECFILE_FIFO:
757 			fattr->cf_mode |= S_IFIFO;
758 			break;
759 		case NFS_SPECFILE_SOCK:
760 			fattr->cf_mode |= S_IFSOCK;
761 			break;
762 		case NFS_SPECFILE_LNK:
763 			fattr->cf_mode |= S_IFLNK;
764 			break;
765 		default:
766 			WARN_ON_ONCE(1);
767 			return false;
768 		}
769 		goto out;
770 	}
771 
772 	switch (tag) {
773 	case IO_REPARSE_TAG_INTERNAL:
774 		if (!(fattr->cf_cifsattrs & ATTR_DIRECTORY))
775 			return false;
776 		fallthrough;
777 	case IO_REPARSE_TAG_DFS:
778 	case IO_REPARSE_TAG_DFSR:
779 	case IO_REPARSE_TAG_MOUNT_POINT:
780 		/* See cifs_create_junction_fattr() */
781 		fattr->cf_mode = S_IFDIR | 0711;
782 		break;
783 	case IO_REPARSE_TAG_LX_SYMLINK:
784 	case IO_REPARSE_TAG_LX_FIFO:
785 	case IO_REPARSE_TAG_AF_UNIX:
786 	case IO_REPARSE_TAG_LX_CHR:
787 	case IO_REPARSE_TAG_LX_BLK:
788 		wsl_to_fattr(data, cifs_sb, tag, fattr);
789 		break;
790 	case 0: /* SMB1 symlink */
791 	case IO_REPARSE_TAG_SYMLINK:
792 	case IO_REPARSE_TAG_NFS:
793 		fattr->cf_mode |= S_IFLNK;
794 		break;
795 	default:
796 		return false;
797 	}
798 out:
799 	fattr->cf_dtype = S_DT(fattr->cf_mode);
800 	return true;
801 }
802