xref: /openbmc/linux/fs/smb/server/smb_common.c (revision 38c8a9a5) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *   Copyright (C) 2018 Samsung Electronics Co., Ltd.
4  *   Copyright (C) 2018 Namjae Jeon <linkinjeon@kernel.org>
5  */
6 
7 #include <linux/user_namespace.h>
8 
9 #include "smb_common.h"
10 #include "server.h"
11 #include "misc.h"
12 #include "smbstatus.h"
13 #include "connection.h"
14 #include "ksmbd_work.h"
15 #include "mgmt/user_session.h"
16 #include "mgmt/user_config.h"
17 #include "mgmt/tree_connect.h"
18 #include "mgmt/share_config.h"
19 
20 /*for shortname implementation */
21 static const char basechars[43] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_-!@#$%";
22 #define MANGLE_BASE (sizeof(basechars) / sizeof(char) - 1)
23 #define MAGIC_CHAR '~'
24 #define PERIOD '.'
25 #define mangle(V) ((char)(basechars[(V) % MANGLE_BASE]))
26 
27 struct smb_protocol {
28 	int		index;
29 	char		*name;
30 	char		*prot;
31 	__u16		prot_id;
32 };
33 
34 static struct smb_protocol smb1_protos[] = {
35 	{
36 		SMB21_PROT,
37 		"\2SMB 2.1",
38 		"SMB2_10",
39 		SMB21_PROT_ID
40 	},
41 	{
42 		SMB2X_PROT,
43 		"\2SMB 2.???",
44 		"SMB2_22",
45 		SMB2X_PROT_ID
46 	},
47 };
48 
49 static struct smb_protocol smb2_protos[] = {
50 	{
51 		SMB21_PROT,
52 		"\2SMB 2.1",
53 		"SMB2_10",
54 		SMB21_PROT_ID
55 	},
56 	{
57 		SMB30_PROT,
58 		"\2SMB 3.0",
59 		"SMB3_00",
60 		SMB30_PROT_ID
61 	},
62 	{
63 		SMB302_PROT,
64 		"\2SMB 3.02",
65 		"SMB3_02",
66 		SMB302_PROT_ID
67 	},
68 	{
69 		SMB311_PROT,
70 		"\2SMB 3.1.1",
71 		"SMB3_11",
72 		SMB311_PROT_ID
73 	},
74 };
75 
76 unsigned int ksmbd_server_side_copy_max_chunk_count(void)
77 {
78 	return 256;
79 }
80 
81 unsigned int ksmbd_server_side_copy_max_chunk_size(void)
82 {
83 	return (2U << 30) - 1;
84 }
85 
86 unsigned int ksmbd_server_side_copy_max_total_size(void)
87 {
88 	return (2U << 30) - 1;
89 }
90 
91 inline int ksmbd_min_protocol(void)
92 {
93 	return SMB21_PROT;
94 }
95 
96 inline int ksmbd_max_protocol(void)
97 {
98 	return SMB311_PROT;
99 }
100 
101 int ksmbd_lookup_protocol_idx(char *str)
102 {
103 	int offt = ARRAY_SIZE(smb1_protos) - 1;
104 	int len = strlen(str);
105 
106 	while (offt >= 0) {
107 		if (!strncmp(str, smb1_protos[offt].prot, len)) {
108 			ksmbd_debug(SMB, "selected %s dialect idx = %d\n",
109 				    smb1_protos[offt].prot, offt);
110 			return smb1_protos[offt].index;
111 		}
112 		offt--;
113 	}
114 
115 	offt = ARRAY_SIZE(smb2_protos) - 1;
116 	while (offt >= 0) {
117 		if (!strncmp(str, smb2_protos[offt].prot, len)) {
118 			ksmbd_debug(SMB, "selected %s dialect idx = %d\n",
119 				    smb2_protos[offt].prot, offt);
120 			return smb2_protos[offt].index;
121 		}
122 		offt--;
123 	}
124 	return -1;
125 }
126 
127 /**
128  * ksmbd_verify_smb_message() - check for valid smb2 request header
129  * @work:	smb work
130  *
131  * check for valid smb signature and packet direction(request/response)
132  *
133  * Return:      0 on success, otherwise -EINVAL
134  */
135 int ksmbd_verify_smb_message(struct ksmbd_work *work)
136 {
137 	struct smb2_hdr *smb2_hdr = ksmbd_req_buf_next(work);
138 	struct smb_hdr *hdr;
139 
140 	if (smb2_hdr->ProtocolId == SMB2_PROTO_NUMBER)
141 		return ksmbd_smb2_check_message(work);
142 
143 	hdr = work->request_buf;
144 	if (*(__le32 *)hdr->Protocol == SMB1_PROTO_NUMBER &&
145 	    hdr->Command == SMB_COM_NEGOTIATE) {
146 		work->conn->outstanding_credits++;
147 		return 0;
148 	}
149 
150 	return -EINVAL;
151 }
152 
153 /**
154  * ksmbd_smb_request() - check for valid smb request type
155  * @conn:	connection instance
156  *
157  * Return:      true on success, otherwise false
158  */
159 bool ksmbd_smb_request(struct ksmbd_conn *conn)
160 {
161 	return conn->request_buf[0] == 0;
162 }
163 
164 static bool supported_protocol(int idx)
165 {
166 	if (idx == SMB2X_PROT &&
167 	    (server_conf.min_protocol >= SMB21_PROT ||
168 	     server_conf.max_protocol <= SMB311_PROT))
169 		return true;
170 
171 	return (server_conf.min_protocol <= idx &&
172 		idx <= server_conf.max_protocol);
173 }
174 
175 static char *next_dialect(char *dialect, int *next_off, int bcount)
176 {
177 	dialect = dialect + *next_off;
178 	*next_off = strnlen(dialect, bcount);
179 	if (dialect[*next_off] != '\0')
180 		return NULL;
181 	return dialect;
182 }
183 
184 static int ksmbd_lookup_dialect_by_name(char *cli_dialects, __le16 byte_count)
185 {
186 	int i, seq_num, bcount, next;
187 	char *dialect;
188 
189 	for (i = ARRAY_SIZE(smb1_protos) - 1; i >= 0; i--) {
190 		seq_num = 0;
191 		next = 0;
192 		dialect = cli_dialects;
193 		bcount = le16_to_cpu(byte_count);
194 		do {
195 			dialect = next_dialect(dialect, &next, bcount);
196 			if (!dialect)
197 				break;
198 			ksmbd_debug(SMB, "client requested dialect %s\n",
199 				    dialect);
200 			if (!strcmp(dialect, smb1_protos[i].name)) {
201 				if (supported_protocol(smb1_protos[i].index)) {
202 					ksmbd_debug(SMB,
203 						    "selected %s dialect\n",
204 						    smb1_protos[i].name);
205 					if (smb1_protos[i].index == SMB1_PROT)
206 						return seq_num;
207 					return smb1_protos[i].prot_id;
208 				}
209 			}
210 			seq_num++;
211 			bcount -= (++next);
212 		} while (bcount > 0);
213 	}
214 
215 	return BAD_PROT_ID;
216 }
217 
218 int ksmbd_lookup_dialect_by_id(__le16 *cli_dialects, __le16 dialects_count)
219 {
220 	int i;
221 	int count;
222 
223 	for (i = ARRAY_SIZE(smb2_protos) - 1; i >= 0; i--) {
224 		count = le16_to_cpu(dialects_count);
225 		while (--count >= 0) {
226 			ksmbd_debug(SMB, "client requested dialect 0x%x\n",
227 				    le16_to_cpu(cli_dialects[count]));
228 			if (le16_to_cpu(cli_dialects[count]) !=
229 					smb2_protos[i].prot_id)
230 				continue;
231 
232 			if (supported_protocol(smb2_protos[i].index)) {
233 				ksmbd_debug(SMB, "selected %s dialect\n",
234 					    smb2_protos[i].name);
235 				return smb2_protos[i].prot_id;
236 			}
237 		}
238 	}
239 
240 	return BAD_PROT_ID;
241 }
242 
243 static int ksmbd_negotiate_smb_dialect(void *buf)
244 {
245 	int smb_buf_length = get_rfc1002_len(buf);
246 	__le32 proto = ((struct smb2_hdr *)smb2_get_msg(buf))->ProtocolId;
247 
248 	if (proto == SMB2_PROTO_NUMBER) {
249 		struct smb2_negotiate_req *req;
250 		int smb2_neg_size =
251 			offsetof(struct smb2_negotiate_req, Dialects);
252 
253 		req = (struct smb2_negotiate_req *)smb2_get_msg(buf);
254 		if (smb2_neg_size > smb_buf_length)
255 			goto err_out;
256 
257 		if (smb2_neg_size + le16_to_cpu(req->DialectCount) * sizeof(__le16) >
258 		    smb_buf_length)
259 			goto err_out;
260 
261 		return ksmbd_lookup_dialect_by_id(req->Dialects,
262 						  req->DialectCount);
263 	}
264 
265 	proto = *(__le32 *)((struct smb_hdr *)buf)->Protocol;
266 	if (proto == SMB1_PROTO_NUMBER) {
267 		struct smb_negotiate_req *req;
268 
269 		req = (struct smb_negotiate_req *)buf;
270 		if (le16_to_cpu(req->ByteCount) < 2)
271 			goto err_out;
272 
273 		if (offsetof(struct smb_negotiate_req, DialectsArray) - 4 +
274 			le16_to_cpu(req->ByteCount) > smb_buf_length) {
275 			goto err_out;
276 		}
277 
278 		return ksmbd_lookup_dialect_by_name(req->DialectsArray,
279 						    req->ByteCount);
280 	}
281 
282 err_out:
283 	return BAD_PROT_ID;
284 }
285 
286 #define SMB_COM_NEGOTIATE_EX	0x0
287 
288 /**
289  * get_smb1_cmd_val() - get smb command value from smb header
290  * @work:	smb work containing smb header
291  *
292  * Return:      smb command value
293  */
294 static u16 get_smb1_cmd_val(struct ksmbd_work *work)
295 {
296 	return SMB_COM_NEGOTIATE_EX;
297 }
298 
299 /**
300  * init_smb1_rsp_hdr() - initialize smb negotiate response header
301  * @work:	smb work containing smb request
302  *
303  * Return:      0 on success, otherwise -EINVAL
304  */
305 static int init_smb1_rsp_hdr(struct ksmbd_work *work)
306 {
307 	struct smb_hdr *rsp_hdr = (struct smb_hdr *)work->response_buf;
308 	struct smb_hdr *rcv_hdr = (struct smb_hdr *)work->request_buf;
309 
310 	/*
311 	 * Remove 4 byte direct TCP header.
312 	 */
313 	*(__be32 *)work->response_buf =
314 		cpu_to_be32(sizeof(struct smb_hdr) - 4);
315 
316 	rsp_hdr->Command = SMB_COM_NEGOTIATE;
317 	*(__le32 *)rsp_hdr->Protocol = SMB1_PROTO_NUMBER;
318 	rsp_hdr->Flags = SMBFLG_RESPONSE;
319 	rsp_hdr->Flags2 = SMBFLG2_UNICODE | SMBFLG2_ERR_STATUS |
320 		SMBFLG2_EXT_SEC | SMBFLG2_IS_LONG_NAME;
321 	rsp_hdr->Pid = rcv_hdr->Pid;
322 	rsp_hdr->Mid = rcv_hdr->Mid;
323 	return 0;
324 }
325 
326 /**
327  * smb1_check_user_session() - check for valid session for a user
328  * @work:	smb work containing smb request buffer
329  *
330  * Return:      0 on success, otherwise error
331  */
332 static int smb1_check_user_session(struct ksmbd_work *work)
333 {
334 	unsigned int cmd = work->conn->ops->get_cmd_val(work);
335 
336 	if (cmd == SMB_COM_NEGOTIATE_EX)
337 		return 0;
338 
339 	return -EINVAL;
340 }
341 
342 /**
343  * smb1_allocate_rsp_buf() - allocate response buffer for a command
344  * @work:	smb work containing smb request
345  *
346  * Return:      0 on success, otherwise -ENOMEM
347  */
348 static int smb1_allocate_rsp_buf(struct ksmbd_work *work)
349 {
350 	work->response_buf = kmalloc(MAX_CIFS_SMALL_BUFFER_SIZE,
351 			GFP_KERNEL | __GFP_ZERO);
352 	work->response_sz = MAX_CIFS_SMALL_BUFFER_SIZE;
353 
354 	if (!work->response_buf) {
355 		pr_err("Failed to allocate %u bytes buffer\n",
356 				MAX_CIFS_SMALL_BUFFER_SIZE);
357 		return -ENOMEM;
358 	}
359 
360 	return 0;
361 }
362 
363 static struct smb_version_ops smb1_server_ops = {
364 	.get_cmd_val = get_smb1_cmd_val,
365 	.init_rsp_hdr = init_smb1_rsp_hdr,
366 	.allocate_rsp_buf = smb1_allocate_rsp_buf,
367 	.check_user_session = smb1_check_user_session,
368 };
369 
370 static int smb1_negotiate(struct ksmbd_work *work)
371 {
372 	return ksmbd_smb_negotiate_common(work, SMB_COM_NEGOTIATE);
373 }
374 
375 static struct smb_version_cmds smb1_server_cmds[1] = {
376 	[SMB_COM_NEGOTIATE_EX]	= { .proc = smb1_negotiate, },
377 };
378 
379 static void init_smb1_server(struct ksmbd_conn *conn)
380 {
381 	conn->ops = &smb1_server_ops;
382 	conn->cmds = smb1_server_cmds;
383 	conn->max_cmds = ARRAY_SIZE(smb1_server_cmds);
384 }
385 
386 void ksmbd_init_smb_server(struct ksmbd_work *work)
387 {
388 	struct ksmbd_conn *conn = work->conn;
389 	__le32 proto;
390 
391 	if (conn->need_neg == false)
392 		return;
393 
394 	proto = *(__le32 *)((struct smb_hdr *)work->request_buf)->Protocol;
395 	if (proto == SMB1_PROTO_NUMBER)
396 		init_smb1_server(conn);
397 	else
398 		init_smb3_11_server(conn);
399 }
400 
401 int ksmbd_populate_dot_dotdot_entries(struct ksmbd_work *work, int info_level,
402 				      struct ksmbd_file *dir,
403 				      struct ksmbd_dir_info *d_info,
404 				      char *search_pattern,
405 				      int (*fn)(struct ksmbd_conn *, int,
406 						struct ksmbd_dir_info *,
407 						struct ksmbd_kstat *))
408 {
409 	int i, rc = 0;
410 	struct ksmbd_conn *conn = work->conn;
411 	struct mnt_idmap *idmap = file_mnt_idmap(dir->filp);
412 
413 	for (i = 0; i < 2; i++) {
414 		struct kstat kstat;
415 		struct ksmbd_kstat ksmbd_kstat;
416 		struct dentry *dentry;
417 
418 		if (!dir->dot_dotdot[i]) { /* fill dot entry info */
419 			if (i == 0) {
420 				d_info->name = ".";
421 				d_info->name_len = 1;
422 				dentry = dir->filp->f_path.dentry;
423 			} else {
424 				d_info->name = "..";
425 				d_info->name_len = 2;
426 				dentry = dir->filp->f_path.dentry->d_parent;
427 			}
428 
429 			if (!match_pattern(d_info->name, d_info->name_len,
430 					   search_pattern)) {
431 				dir->dot_dotdot[i] = 1;
432 				continue;
433 			}
434 
435 			ksmbd_kstat.kstat = &kstat;
436 			ksmbd_vfs_fill_dentry_attrs(work,
437 						    idmap,
438 						    dentry,
439 						    &ksmbd_kstat);
440 			rc = fn(conn, info_level, d_info, &ksmbd_kstat);
441 			if (rc)
442 				break;
443 			if (d_info->out_buf_len <= 0)
444 				break;
445 
446 			dir->dot_dotdot[i] = 1;
447 			if (d_info->flags & SMB2_RETURN_SINGLE_ENTRY) {
448 				d_info->out_buf_len = 0;
449 				break;
450 			}
451 		}
452 	}
453 
454 	return rc;
455 }
456 
457 /**
458  * ksmbd_extract_shortname() - get shortname from long filename
459  * @conn:	connection instance
460  * @longname:	source long filename
461  * @shortname:	destination short filename
462  *
463  * Return:	shortname length or 0 when source long name is '.' or '..'
464  * TODO: Though this function comforms the restriction of 8.3 Filename spec,
465  * but the result is different with Windows 7's one. need to check.
466  */
467 int ksmbd_extract_shortname(struct ksmbd_conn *conn, const char *longname,
468 			    char *shortname)
469 {
470 	const char *p;
471 	char base[9], extension[4];
472 	char out[13] = {0};
473 	int baselen = 0;
474 	int extlen = 0, len = 0;
475 	unsigned int csum = 0;
476 	const unsigned char *ptr;
477 	bool dot_present = true;
478 
479 	p = longname;
480 	if ((*p == '.') || (!(strcmp(p, "..")))) {
481 		/*no mangling required */
482 		return 0;
483 	}
484 
485 	p = strrchr(longname, '.');
486 	if (p == longname) { /*name starts with a dot*/
487 		strscpy(extension, "___", strlen("___"));
488 	} else {
489 		if (p) {
490 			p++;
491 			while (*p && extlen < 3) {
492 				if (*p != '.')
493 					extension[extlen++] = toupper(*p);
494 				p++;
495 			}
496 			extension[extlen] = '\0';
497 		} else {
498 			dot_present = false;
499 		}
500 	}
501 
502 	p = longname;
503 	if (*p == '.') {
504 		p++;
505 		longname++;
506 	}
507 	while (*p && (baselen < 5)) {
508 		if (*p != '.')
509 			base[baselen++] = toupper(*p);
510 		p++;
511 	}
512 
513 	base[baselen] = MAGIC_CHAR;
514 	memcpy(out, base, baselen + 1);
515 
516 	ptr = longname;
517 	len = strlen(longname);
518 	for (; len > 0; len--, ptr++)
519 		csum += *ptr;
520 
521 	csum = csum % (MANGLE_BASE * MANGLE_BASE);
522 	out[baselen + 1] = mangle(csum / MANGLE_BASE);
523 	out[baselen + 2] = mangle(csum);
524 	out[baselen + 3] = PERIOD;
525 
526 	if (dot_present)
527 		memcpy(&out[baselen + 4], extension, 4);
528 	else
529 		out[baselen + 4] = '\0';
530 	smbConvertToUTF16((__le16 *)shortname, out, PATH_MAX,
531 			  conn->local_nls, 0);
532 	len = strlen(out) * 2;
533 	return len;
534 }
535 
536 static int __smb2_negotiate(struct ksmbd_conn *conn)
537 {
538 	return (conn->dialect >= SMB20_PROT_ID &&
539 		conn->dialect <= SMB311_PROT_ID);
540 }
541 
542 static int smb_handle_negotiate(struct ksmbd_work *work)
543 {
544 	struct smb_negotiate_rsp *neg_rsp = work->response_buf;
545 
546 	ksmbd_debug(SMB, "Unsupported SMB1 protocol\n");
547 
548 	/* Add 2 byte bcc and 2 byte DialectIndex. */
549 	inc_rfc1001_len(work->response_buf, 4);
550 	neg_rsp->hdr.Status.CifsError = STATUS_SUCCESS;
551 
552 	neg_rsp->hdr.WordCount = 1;
553 	neg_rsp->DialectIndex = cpu_to_le16(work->conn->dialect);
554 	neg_rsp->ByteCount = 0;
555 	return 0;
556 }
557 
558 int ksmbd_smb_negotiate_common(struct ksmbd_work *work, unsigned int command)
559 {
560 	struct ksmbd_conn *conn = work->conn;
561 	int ret;
562 
563 	conn->dialect =
564 		ksmbd_negotiate_smb_dialect(work->request_buf);
565 	ksmbd_debug(SMB, "conn->dialect 0x%x\n", conn->dialect);
566 
567 	if (command == SMB2_NEGOTIATE_HE) {
568 		ret = smb2_handle_negotiate(work);
569 		return ret;
570 	}
571 
572 	if (command == SMB_COM_NEGOTIATE) {
573 		if (__smb2_negotiate(conn)) {
574 			init_smb3_11_server(conn);
575 			init_smb2_neg_rsp(work);
576 			ksmbd_debug(SMB, "Upgrade to SMB2 negotiation\n");
577 			return 0;
578 		}
579 		return smb_handle_negotiate(work);
580 	}
581 
582 	pr_err("Unknown SMB negotiation command: %u\n", command);
583 	return -EINVAL;
584 }
585 
586 enum SHARED_MODE_ERRORS {
587 	SHARE_DELETE_ERROR,
588 	SHARE_READ_ERROR,
589 	SHARE_WRITE_ERROR,
590 	FILE_READ_ERROR,
591 	FILE_WRITE_ERROR,
592 	FILE_DELETE_ERROR,
593 };
594 
595 static const char * const shared_mode_errors[] = {
596 	"Current access mode does not permit SHARE_DELETE",
597 	"Current access mode does not permit SHARE_READ",
598 	"Current access mode does not permit SHARE_WRITE",
599 	"Desired access mode does not permit FILE_READ",
600 	"Desired access mode does not permit FILE_WRITE",
601 	"Desired access mode does not permit FILE_DELETE",
602 };
603 
604 static void smb_shared_mode_error(int error, struct ksmbd_file *prev_fp,
605 				  struct ksmbd_file *curr_fp)
606 {
607 	ksmbd_debug(SMB, "%s\n", shared_mode_errors[error]);
608 	ksmbd_debug(SMB, "Current mode: 0x%x Desired mode: 0x%x\n",
609 		    prev_fp->saccess, curr_fp->daccess);
610 }
611 
612 int ksmbd_smb_check_shared_mode(struct file *filp, struct ksmbd_file *curr_fp)
613 {
614 	int rc = 0;
615 	struct ksmbd_file *prev_fp;
616 
617 	/*
618 	 * Lookup fp in master fp list, and check desired access and
619 	 * shared mode between previous open and current open.
620 	 */
621 	read_lock(&curr_fp->f_ci->m_lock);
622 	list_for_each_entry(prev_fp, &curr_fp->f_ci->m_fp_list, node) {
623 		if (file_inode(filp) != file_inode(prev_fp->filp))
624 			continue;
625 
626 		if (filp == prev_fp->filp)
627 			continue;
628 
629 		if (ksmbd_stream_fd(prev_fp) && ksmbd_stream_fd(curr_fp))
630 			if (strcmp(prev_fp->stream.name, curr_fp->stream.name))
631 				continue;
632 
633 		if (prev_fp->attrib_only != curr_fp->attrib_only)
634 			continue;
635 
636 		if (!(prev_fp->saccess & FILE_SHARE_DELETE_LE) &&
637 		    curr_fp->daccess & FILE_DELETE_LE) {
638 			smb_shared_mode_error(SHARE_DELETE_ERROR,
639 					      prev_fp,
640 					      curr_fp);
641 			rc = -EPERM;
642 			break;
643 		}
644 
645 		/*
646 		 * Only check FILE_SHARE_DELETE if stream opened and
647 		 * normal file opened.
648 		 */
649 		if (ksmbd_stream_fd(prev_fp) && !ksmbd_stream_fd(curr_fp))
650 			continue;
651 
652 		if (!(prev_fp->saccess & FILE_SHARE_READ_LE) &&
653 		    curr_fp->daccess & (FILE_EXECUTE_LE | FILE_READ_DATA_LE)) {
654 			smb_shared_mode_error(SHARE_READ_ERROR,
655 					      prev_fp,
656 					      curr_fp);
657 			rc = -EPERM;
658 			break;
659 		}
660 
661 		if (!(prev_fp->saccess & FILE_SHARE_WRITE_LE) &&
662 		    curr_fp->daccess & (FILE_WRITE_DATA_LE | FILE_APPEND_DATA_LE)) {
663 			smb_shared_mode_error(SHARE_WRITE_ERROR,
664 					      prev_fp,
665 					      curr_fp);
666 			rc = -EPERM;
667 			break;
668 		}
669 
670 		if (prev_fp->daccess & (FILE_EXECUTE_LE | FILE_READ_DATA_LE) &&
671 		    !(curr_fp->saccess & FILE_SHARE_READ_LE)) {
672 			smb_shared_mode_error(FILE_READ_ERROR,
673 					      prev_fp,
674 					      curr_fp);
675 			rc = -EPERM;
676 			break;
677 		}
678 
679 		if (prev_fp->daccess & (FILE_WRITE_DATA_LE | FILE_APPEND_DATA_LE) &&
680 		    !(curr_fp->saccess & FILE_SHARE_WRITE_LE)) {
681 			smb_shared_mode_error(FILE_WRITE_ERROR,
682 					      prev_fp,
683 					      curr_fp);
684 			rc = -EPERM;
685 			break;
686 		}
687 
688 		if (prev_fp->daccess & FILE_DELETE_LE &&
689 		    !(curr_fp->saccess & FILE_SHARE_DELETE_LE)) {
690 			smb_shared_mode_error(FILE_DELETE_ERROR,
691 					      prev_fp,
692 					      curr_fp);
693 			rc = -EPERM;
694 			break;
695 		}
696 	}
697 	read_unlock(&curr_fp->f_ci->m_lock);
698 
699 	return rc;
700 }
701 
702 bool is_asterisk(char *p)
703 {
704 	return p && p[0] == '*';
705 }
706 
707 int ksmbd_override_fsids(struct ksmbd_work *work)
708 {
709 	struct ksmbd_session *sess = work->sess;
710 	struct ksmbd_share_config *share = work->tcon->share_conf;
711 	struct cred *cred;
712 	struct group_info *gi;
713 	unsigned int uid;
714 	unsigned int gid;
715 
716 	uid = user_uid(sess->user);
717 	gid = user_gid(sess->user);
718 	if (share->force_uid != KSMBD_SHARE_INVALID_UID)
719 		uid = share->force_uid;
720 	if (share->force_gid != KSMBD_SHARE_INVALID_GID)
721 		gid = share->force_gid;
722 
723 	cred = prepare_kernel_cred(&init_task);
724 	if (!cred)
725 		return -ENOMEM;
726 
727 	cred->fsuid = make_kuid(&init_user_ns, uid);
728 	cred->fsgid = make_kgid(&init_user_ns, gid);
729 
730 	gi = groups_alloc(0);
731 	if (!gi) {
732 		abort_creds(cred);
733 		return -ENOMEM;
734 	}
735 	set_groups(cred, gi);
736 	put_group_info(gi);
737 
738 	if (!uid_eq(cred->fsuid, GLOBAL_ROOT_UID))
739 		cred->cap_effective = cap_drop_fs_set(cred->cap_effective);
740 
741 	WARN_ON(work->saved_cred);
742 	work->saved_cred = override_creds(cred);
743 	if (!work->saved_cred) {
744 		abort_creds(cred);
745 		return -EINVAL;
746 	}
747 	return 0;
748 }
749 
750 void ksmbd_revert_fsids(struct ksmbd_work *work)
751 {
752 	const struct cred *cred;
753 
754 	WARN_ON(!work->saved_cred);
755 
756 	cred = current_cred();
757 	revert_creds(work->saved_cred);
758 	put_cred(cred);
759 	work->saved_cred = NULL;
760 }
761 
762 __le32 smb_map_generic_desired_access(__le32 daccess)
763 {
764 	if (daccess & FILE_GENERIC_READ_LE) {
765 		daccess |= cpu_to_le32(GENERIC_READ_FLAGS);
766 		daccess &= ~FILE_GENERIC_READ_LE;
767 	}
768 
769 	if (daccess & FILE_GENERIC_WRITE_LE) {
770 		daccess |= cpu_to_le32(GENERIC_WRITE_FLAGS);
771 		daccess &= ~FILE_GENERIC_WRITE_LE;
772 	}
773 
774 	if (daccess & FILE_GENERIC_EXECUTE_LE) {
775 		daccess |= cpu_to_le32(GENERIC_EXECUTE_FLAGS);
776 		daccess &= ~FILE_GENERIC_EXECUTE_LE;
777 	}
778 
779 	if (daccess & FILE_GENERIC_ALL_LE) {
780 		daccess |= cpu_to_le32(GENERIC_ALL_FLAGS);
781 		daccess &= ~FILE_GENERIC_ALL_LE;
782 	}
783 
784 	return daccess;
785 }
786