1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *   Copyright (C) 2016 Namjae Jeon <linkinjeon@kernel.org>
4 *   Copyright (C) 2018 Samsung Electronics Co., Ltd.
5 */
6
7#include "glob.h"
8#include "nterr.h"
9#include "smb_common.h"
10#include "smbstatus.h"
11#include "mgmt/user_session.h"
12#include "connection.h"
13
14static int check_smb2_hdr(struct smb2_hdr *hdr)
15{
16	/*
17	 * Make sure that this really is an SMB, that it is a response.
18	 */
19	if (hdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
20		return 1;
21	return 0;
22}
23
24/*
25 *  The following table defines the expected "StructureSize" of SMB2 requests
26 *  in order by SMB2 command.  This is similar to "wct" in SMB/CIFS requests.
27 *
28 *  Note that commands are defined in smb2pdu.h in le16 but the array below is
29 *  indexed by command in host byte order
30 */
31static const __le16 smb2_req_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = {
32	/* SMB2_NEGOTIATE */ cpu_to_le16(36),
33	/* SMB2_SESSION_SETUP */ cpu_to_le16(25),
34	/* SMB2_LOGOFF */ cpu_to_le16(4),
35	/* SMB2_TREE_CONNECT */ cpu_to_le16(9),
36	/* SMB2_TREE_DISCONNECT */ cpu_to_le16(4),
37	/* SMB2_CREATE */ cpu_to_le16(57),
38	/* SMB2_CLOSE */ cpu_to_le16(24),
39	/* SMB2_FLUSH */ cpu_to_le16(24),
40	/* SMB2_READ */ cpu_to_le16(49),
41	/* SMB2_WRITE */ cpu_to_le16(49),
42	/* SMB2_LOCK */ cpu_to_le16(48),
43	/* SMB2_IOCTL */ cpu_to_le16(57),
44	/* SMB2_CANCEL */ cpu_to_le16(4),
45	/* SMB2_ECHO */ cpu_to_le16(4),
46	/* SMB2_QUERY_DIRECTORY */ cpu_to_le16(33),
47	/* SMB2_CHANGE_NOTIFY */ cpu_to_le16(32),
48	/* SMB2_QUERY_INFO */ cpu_to_le16(41),
49	/* SMB2_SET_INFO */ cpu_to_le16(33),
50	/* use 44 for lease break */
51	/* SMB2_OPLOCK_BREAK */ cpu_to_le16(36)
52};
53
54/*
55 * The size of the variable area depends on the offset and length fields
56 * located in different fields for various SMB2 requests. SMB2 requests
57 * with no variable length info, show an offset of zero for the offset field.
58 */
59static const bool has_smb2_data_area[NUMBER_OF_SMB2_COMMANDS] = {
60	/* SMB2_NEGOTIATE */ true,
61	/* SMB2_SESSION_SETUP */ true,
62	/* SMB2_LOGOFF */ false,
63	/* SMB2_TREE_CONNECT */	true,
64	/* SMB2_TREE_DISCONNECT */ false,
65	/* SMB2_CREATE */ true,
66	/* SMB2_CLOSE */ false,
67	/* SMB2_FLUSH */ false,
68	/* SMB2_READ */	true,
69	/* SMB2_WRITE */ true,
70	/* SMB2_LOCK */	true,
71	/* SMB2_IOCTL */ true,
72	/* SMB2_CANCEL */ false, /* BB CHECK this not listed in documentation */
73	/* SMB2_ECHO */ false,
74	/* SMB2_QUERY_DIRECTORY */ true,
75	/* SMB2_CHANGE_NOTIFY */ false,
76	/* SMB2_QUERY_INFO */ true,
77	/* SMB2_SET_INFO */ true,
78	/* SMB2_OPLOCK_BREAK */ false
79};
80
81/*
82 * Set length of the data area and the offset to arguments.
83 * if they are invalid, return error.
84 */
85static int smb2_get_data_area_len(unsigned int *off, unsigned int *len,
86				  struct smb2_hdr *hdr)
87{
88	int ret = 0;
89
90	*off = 0;
91	*len = 0;
92
93	/*
94	 * Following commands have data areas so we have to get the location
95	 * of the data buffer offset and data buffer length for the particular
96	 * command.
97	 */
98	switch (hdr->Command) {
99	case SMB2_SESSION_SETUP:
100		*off = le16_to_cpu(((struct smb2_sess_setup_req *)hdr)->SecurityBufferOffset);
101		*len = le16_to_cpu(((struct smb2_sess_setup_req *)hdr)->SecurityBufferLength);
102		break;
103	case SMB2_TREE_CONNECT:
104		*off = max_t(unsigned short int,
105			     le16_to_cpu(((struct smb2_tree_connect_req *)hdr)->PathOffset),
106			     offsetof(struct smb2_tree_connect_req, Buffer));
107		*len = le16_to_cpu(((struct smb2_tree_connect_req *)hdr)->PathLength);
108		break;
109	case SMB2_CREATE:
110	{
111		unsigned short int name_off =
112			max_t(unsigned short int,
113			      le16_to_cpu(((struct smb2_create_req *)hdr)->NameOffset),
114			      offsetof(struct smb2_create_req, Buffer));
115		unsigned short int name_len =
116			le16_to_cpu(((struct smb2_create_req *)hdr)->NameLength);
117
118		if (((struct smb2_create_req *)hdr)->CreateContextsLength) {
119			*off = le32_to_cpu(((struct smb2_create_req *)
120				hdr)->CreateContextsOffset);
121			*len = le32_to_cpu(((struct smb2_create_req *)
122				hdr)->CreateContextsLength);
123			if (!name_len)
124				break;
125
126			if (name_off + name_len < (u64)*off + *len)
127				break;
128		}
129
130		*off = name_off;
131		*len = name_len;
132		break;
133	}
134	case SMB2_QUERY_INFO:
135		*off = max_t(unsigned int,
136			     le16_to_cpu(((struct smb2_query_info_req *)hdr)->InputBufferOffset),
137			     offsetof(struct smb2_query_info_req, Buffer));
138		*len = le32_to_cpu(((struct smb2_query_info_req *)hdr)->InputBufferLength);
139		break;
140	case SMB2_SET_INFO:
141		*off = max_t(unsigned int,
142			     le16_to_cpu(((struct smb2_set_info_req *)hdr)->BufferOffset),
143			     offsetof(struct smb2_set_info_req, Buffer));
144		*len = le32_to_cpu(((struct smb2_set_info_req *)hdr)->BufferLength);
145		break;
146	case SMB2_READ:
147		*off = le16_to_cpu(((struct smb2_read_req *)hdr)->ReadChannelInfoOffset);
148		*len = le16_to_cpu(((struct smb2_read_req *)hdr)->ReadChannelInfoLength);
149		break;
150	case SMB2_WRITE:
151		if (((struct smb2_write_req *)hdr)->DataOffset ||
152		    ((struct smb2_write_req *)hdr)->Length) {
153			*off = max_t(unsigned short int,
154				     le16_to_cpu(((struct smb2_write_req *)hdr)->DataOffset),
155				     offsetof(struct smb2_write_req, Buffer));
156			*len = le32_to_cpu(((struct smb2_write_req *)hdr)->Length);
157			break;
158		}
159
160		*off = le16_to_cpu(((struct smb2_write_req *)hdr)->WriteChannelInfoOffset);
161		*len = le16_to_cpu(((struct smb2_write_req *)hdr)->WriteChannelInfoLength);
162		break;
163	case SMB2_QUERY_DIRECTORY:
164		*off = max_t(unsigned short int,
165			     le16_to_cpu(((struct smb2_query_directory_req *)hdr)->FileNameOffset),
166			     offsetof(struct smb2_query_directory_req, Buffer));
167		*len = le16_to_cpu(((struct smb2_query_directory_req *)hdr)->FileNameLength);
168		break;
169	case SMB2_LOCK:
170	{
171		unsigned short lock_count;
172
173		lock_count = le16_to_cpu(((struct smb2_lock_req *)hdr)->LockCount);
174		if (lock_count > 0) {
175			*off = offsetof(struct smb2_lock_req, locks);
176			*len = sizeof(struct smb2_lock_element) * lock_count;
177		}
178		break;
179	}
180	case SMB2_IOCTL:
181		*off = max_t(unsigned int,
182			     le32_to_cpu(((struct smb2_ioctl_req *)hdr)->InputOffset),
183			     offsetof(struct smb2_ioctl_req, Buffer));
184		*len = le32_to_cpu(((struct smb2_ioctl_req *)hdr)->InputCount);
185		break;
186	default:
187		ksmbd_debug(SMB, "no length check for command\n");
188		break;
189	}
190
191	if (*off > 4096) {
192		ksmbd_debug(SMB, "offset %d too large\n", *off);
193		ret = -EINVAL;
194	} else if ((u64)*off + *len > MAX_STREAM_PROT_LEN) {
195		ksmbd_debug(SMB, "Request is larger than maximum stream protocol length(%u): %llu\n",
196			    MAX_STREAM_PROT_LEN, (u64)*off + *len);
197		ret = -EINVAL;
198	}
199
200	return ret;
201}
202
203/*
204 * Calculate the size of the SMB message based on the fixed header
205 * portion, the number of word parameters and the data portion of the message.
206 */
207static int smb2_calc_size(void *buf, unsigned int *len)
208{
209	struct smb2_pdu *pdu = (struct smb2_pdu *)buf;
210	struct smb2_hdr *hdr = &pdu->hdr;
211	unsigned int offset; /* the offset from the beginning of SMB to data area */
212	unsigned int data_length; /* the length of the variable length data area */
213	int ret;
214
215	/* Structure Size has already been checked to make sure it is 64 */
216	*len = le16_to_cpu(hdr->StructureSize);
217
218	/*
219	 * StructureSize2, ie length of fixed parameter area has already
220	 * been checked to make sure it is the correct length.
221	 */
222	*len += le16_to_cpu(pdu->StructureSize2);
223	/*
224	 * StructureSize2 of smb2_lock pdu is set to 48, indicating
225	 * the size of smb2 lock request with single smb2_lock_element
226	 * regardless of number of locks. Subtract single
227	 * smb2_lock_element for correct buffer size check.
228	 */
229	if (hdr->Command == SMB2_LOCK)
230		*len -= sizeof(struct smb2_lock_element);
231
232	if (has_smb2_data_area[le16_to_cpu(hdr->Command)] == false)
233		goto calc_size_exit;
234
235	ret = smb2_get_data_area_len(&offset, &data_length, hdr);
236	if (ret)
237		return ret;
238	ksmbd_debug(SMB, "SMB2 data length %u offset %u\n", data_length,
239		    offset);
240
241	if (data_length > 0) {
242		/*
243		 * Check to make sure that data area begins after fixed area,
244		 * Note that last byte of the fixed area is part of data area
245		 * for some commands, typically those with odd StructureSize,
246		 * so we must add one to the calculation.
247		 */
248		if (offset + 1 < *len) {
249			ksmbd_debug(SMB,
250				    "data area offset %d overlaps SMB2 header %u\n",
251				    offset + 1, *len);
252			return -EINVAL;
253		}
254
255		*len = offset + data_length;
256	}
257
258calc_size_exit:
259	ksmbd_debug(SMB, "SMB2 len %u\n", *len);
260	return 0;
261}
262
263static inline int smb2_query_info_req_len(struct smb2_query_info_req *h)
264{
265	return le32_to_cpu(h->InputBufferLength) +
266		le32_to_cpu(h->OutputBufferLength);
267}
268
269static inline int smb2_set_info_req_len(struct smb2_set_info_req *h)
270{
271	return le32_to_cpu(h->BufferLength);
272}
273
274static inline int smb2_read_req_len(struct smb2_read_req *h)
275{
276	return le32_to_cpu(h->Length);
277}
278
279static inline int smb2_write_req_len(struct smb2_write_req *h)
280{
281	return le32_to_cpu(h->Length);
282}
283
284static inline int smb2_query_dir_req_len(struct smb2_query_directory_req *h)
285{
286	return le32_to_cpu(h->OutputBufferLength);
287}
288
289static inline int smb2_ioctl_req_len(struct smb2_ioctl_req *h)
290{
291	return le32_to_cpu(h->InputCount) +
292		le32_to_cpu(h->OutputCount);
293}
294
295static inline int smb2_ioctl_resp_len(struct smb2_ioctl_req *h)
296{
297	return le32_to_cpu(h->MaxInputResponse) +
298		le32_to_cpu(h->MaxOutputResponse);
299}
300
301static int smb2_validate_credit_charge(struct ksmbd_conn *conn,
302				       struct smb2_hdr *hdr)
303{
304	unsigned int req_len = 0, expect_resp_len = 0, calc_credit_num, max_len;
305	unsigned short credit_charge = le16_to_cpu(hdr->CreditCharge);
306	void *__hdr = hdr;
307	int ret = 0;
308
309	switch (hdr->Command) {
310	case SMB2_QUERY_INFO:
311		req_len = smb2_query_info_req_len(__hdr);
312		break;
313	case SMB2_SET_INFO:
314		req_len = smb2_set_info_req_len(__hdr);
315		break;
316	case SMB2_READ:
317		req_len = smb2_read_req_len(__hdr);
318		break;
319	case SMB2_WRITE:
320		req_len = smb2_write_req_len(__hdr);
321		break;
322	case SMB2_QUERY_DIRECTORY:
323		req_len = smb2_query_dir_req_len(__hdr);
324		break;
325	case SMB2_IOCTL:
326		req_len = smb2_ioctl_req_len(__hdr);
327		expect_resp_len = smb2_ioctl_resp_len(__hdr);
328		break;
329	case SMB2_CANCEL:
330		return 0;
331	default:
332		req_len = 1;
333		break;
334	}
335
336	credit_charge = max_t(unsigned short, credit_charge, 1);
337	max_len = max_t(unsigned int, req_len, expect_resp_len);
338	calc_credit_num = DIV_ROUND_UP(max_len, SMB2_MAX_BUFFER_SIZE);
339
340	if (credit_charge < calc_credit_num) {
341		ksmbd_debug(SMB, "Insufficient credit charge, given: %d, needed: %d\n",
342			    credit_charge, calc_credit_num);
343		return 1;
344	} else if (credit_charge > conn->vals->max_credits) {
345		ksmbd_debug(SMB, "Too large credit charge: %d\n", credit_charge);
346		return 1;
347	}
348
349	spin_lock(&conn->credits_lock);
350	if (credit_charge > conn->total_credits) {
351		ksmbd_debug(SMB, "Insufficient credits granted, given: %u, granted: %u\n",
352			    credit_charge, conn->total_credits);
353		ret = 1;
354	}
355
356	if ((u64)conn->outstanding_credits + credit_charge > conn->total_credits) {
357		ksmbd_debug(SMB, "Limits exceeding the maximum allowable outstanding requests, given : %u, pending : %u\n",
358			    credit_charge, conn->outstanding_credits);
359		ret = 1;
360	} else
361		conn->outstanding_credits += credit_charge;
362
363	spin_unlock(&conn->credits_lock);
364
365	return ret;
366}
367
368int ksmbd_smb2_check_message(struct ksmbd_work *work)
369{
370	struct smb2_pdu *pdu = ksmbd_req_buf_next(work);
371	struct smb2_hdr *hdr = &pdu->hdr;
372	int command;
373	__u32 clc_len;  /* calculated length */
374	__u32 len = get_rfc1002_len(work->request_buf);
375	__u32 req_struct_size, next_cmd = le32_to_cpu(hdr->NextCommand);
376
377	if ((u64)work->next_smb2_rcv_hdr_off + next_cmd > len) {
378		pr_err("next command(%u) offset exceeds smb msg size\n",
379				next_cmd);
380		return 1;
381	}
382
383	if (next_cmd > 0)
384		len = next_cmd;
385	else if (work->next_smb2_rcv_hdr_off)
386		len -= work->next_smb2_rcv_hdr_off;
387
388	if (check_smb2_hdr(hdr))
389		return 1;
390
391	if (hdr->StructureSize != SMB2_HEADER_STRUCTURE_SIZE) {
392		ksmbd_debug(SMB, "Illegal structure size %u\n",
393			    le16_to_cpu(hdr->StructureSize));
394		return 1;
395	}
396
397	command = le16_to_cpu(hdr->Command);
398	if (command >= NUMBER_OF_SMB2_COMMANDS) {
399		ksmbd_debug(SMB, "Illegal SMB2 command %d\n", command);
400		return 1;
401	}
402
403	if (smb2_req_struct_sizes[command] != pdu->StructureSize2) {
404		if (!(command == SMB2_OPLOCK_BREAK_HE &&
405		    (le16_to_cpu(pdu->StructureSize2) == OP_BREAK_STRUCT_SIZE_20 ||
406		    le16_to_cpu(pdu->StructureSize2) == OP_BREAK_STRUCT_SIZE_21))) {
407			/* special case for SMB2.1 lease break message */
408			ksmbd_debug(SMB,
409				"Illegal request size %u for command %d\n",
410				le16_to_cpu(pdu->StructureSize2), command);
411			return 1;
412		}
413	}
414
415	req_struct_size = le16_to_cpu(pdu->StructureSize2) +
416		__SMB2_HEADER_STRUCTURE_SIZE;
417	if (command == SMB2_LOCK_HE)
418		req_struct_size -= sizeof(struct smb2_lock_element);
419
420	if (req_struct_size > len + 1)
421		return 1;
422
423	if (smb2_calc_size(hdr, &clc_len))
424		return 1;
425
426	if (len != clc_len) {
427		/* client can return one byte more due to implied bcc[0] */
428		if (clc_len == len + 1)
429			goto validate_credit;
430
431		/*
432		 * Some windows servers (win2016) will pad also the final
433		 * PDU in a compound to 8 bytes.
434		 */
435		if (ALIGN(clc_len, 8) == len)
436			goto validate_credit;
437
438		/*
439		 * SMB2 NEGOTIATE request will be validated when message
440		 * handling proceeds.
441		 */
442		if (command == SMB2_NEGOTIATE_HE)
443			goto validate_credit;
444
445		/*
446		 * Allow a message that padded to 8byte boundary.
447		 * Linux 4.19.217 with smb 3.0.2 are sometimes
448		 * sending messages where the cls_len is exactly
449		 * 8 bytes less than len.
450		 */
451		if (clc_len < len && (len - clc_len) <= 8)
452			goto validate_credit;
453
454		pr_err_ratelimited(
455			    "cli req too short, len %d not %d. cmd:%d mid:%llu\n",
456			    len, clc_len, command,
457			    le64_to_cpu(hdr->MessageId));
458
459		return 1;
460	}
461
462validate_credit:
463	if ((work->conn->vals->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU) &&
464	    smb2_validate_credit_charge(work->conn, hdr))
465		return 1;
466
467	return 0;
468}
469
470int smb2_negotiate_request(struct ksmbd_work *work)
471{
472	return ksmbd_smb_negotiate_common(work, SMB2_NEGOTIATE_HE);
473}
474