smb2misc.c

  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 "smb_common.h"
  9#include "../common/smb2status.h"
 10#include "mgmt/user_session.h"
 11#include "connection.h"
 12
 13static int check_smb2_hdr(struct smb2_hdr *hdr)
 14{
 15	/*
 16	 * Make sure that this really is an SMB, that it is a response.
 17	 */
 18	if (hdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
 19		return 1;
 20	return 0;
 21}
 22
 23/*
 24 *  The following table defines the expected "StructureSize" of SMB2 requests
 25 *  in order by SMB2 command.  This is similar to "wct" in SMB/CIFS requests.
 26 *
 27 *  Note that commands are defined in smb2pdu.h in le16 but the array below is
 28 *  indexed by command in host byte order
 29 */
 30static const __le16 smb2_req_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = {
 31	/* SMB2_NEGOTIATE */ cpu_to_le16(36),
 32	/* SMB2_SESSION_SETUP */ cpu_to_le16(25),
 33	/* SMB2_LOGOFF */ cpu_to_le16(4),
 34	/* SMB2_TREE_CONNECT */ cpu_to_le16(9),
 35	/* SMB2_TREE_DISCONNECT */ cpu_to_le16(4),
 36	/* SMB2_CREATE */ cpu_to_le16(57),
 37	/* SMB2_CLOSE */ cpu_to_le16(24),
 38	/* SMB2_FLUSH */ cpu_to_le16(24),
 39	/* SMB2_READ */ cpu_to_le16(49),
 40	/* SMB2_WRITE */ cpu_to_le16(49),
 41	/* SMB2_LOCK */ cpu_to_le16(48),
 42	/* SMB2_IOCTL */ cpu_to_le16(57),
 43	/* SMB2_CANCEL */ cpu_to_le16(4),
 44	/* SMB2_ECHO */ cpu_to_le16(4),
 45	/* SMB2_QUERY_DIRECTORY */ cpu_to_le16(33),
 46	/* SMB2_CHANGE_NOTIFY */ cpu_to_le16(32),
 47	/* SMB2_QUERY_INFO */ cpu_to_le16(41),
 48	/* SMB2_SET_INFO */ cpu_to_le16(33),
 49	/* use 44 for lease break */
 50	/* SMB2_OPLOCK_BREAK */ cpu_to_le16(36)
 51};
 52
 53/*
 54 * The size of the variable area depends on the offset and length fields
 55 * located in different fields for various SMB2 requests. SMB2 requests
 56 * with no variable length info, show an offset of zero for the offset field.
 57 */
 58static const bool has_smb2_data_area[NUMBER_OF_SMB2_COMMANDS] = {
 59	/* SMB2_NEGOTIATE */ true,
 60	/* SMB2_SESSION_SETUP */ true,
 61	/* SMB2_LOGOFF */ false,
 62	/* SMB2_TREE_CONNECT */	true,
 63	/* SMB2_TREE_DISCONNECT */ false,
 64	/* SMB2_CREATE */ true,
 65	/* SMB2_CLOSE */ false,
 66	/* SMB2_FLUSH */ false,
 67	/* SMB2_READ */	true,
 68	/* SMB2_WRITE */ true,
 69	/* SMB2_LOCK */	true,
 70	/* SMB2_IOCTL */ true,
 71	/* SMB2_CANCEL */ false, /* BB CHECK this not listed in documentation */
 72	/* SMB2_ECHO */ false,
 73	/* SMB2_QUERY_DIRECTORY */ true,
 74	/* SMB2_CHANGE_NOTIFY */ false,
 75	/* SMB2_QUERY_INFO */ true,
 76	/* SMB2_SET_INFO */ true,
 77	/* SMB2_OPLOCK_BREAK */ false
 78};
 79
 80/*
 81 * Set length of the data area and the offset to arguments.
 82 * if they are invalid, return error.
 83 */
 84static int smb2_get_data_area_len(unsigned int *off, unsigned int *len,
 85				  struct smb2_hdr *hdr)
 86{
 87	int ret = 0;
 88
 89	*off = 0;
 90	*len = 0;
 91
 92	/*
 93	 * Following commands have data areas so we have to get the location
 94	 * of the data buffer offset and data buffer length for the particular
 95	 * command.
 96	 */
 97	switch (hdr->Command) {
 98	case SMB2_SESSION_SETUP:
 99		*off = le16_to_cpu(((struct smb2_sess_setup_req *)hdr)->SecurityBufferOffset);
100		*len = le16_to_cpu(((struct smb2_sess_setup_req *)hdr)->SecurityBufferLength);
101		break;
102	case SMB2_TREE_CONNECT:
103		*off = max_t(unsigned short int,
104			     le16_to_cpu(((struct smb2_tree_connect_req *)hdr)->PathOffset),
105			     offsetof(struct smb2_tree_connect_req, Buffer));
106		*len = le16_to_cpu(((struct smb2_tree_connect_req *)hdr)->PathLength);
107		break;
108	case SMB2_CREATE:
109	{
110		unsigned short int name_off =
111			max_t(unsigned short int,
112			      le16_to_cpu(((struct smb2_create_req *)hdr)->NameOffset),
113			      offsetof(struct smb2_create_req, Buffer));
114		unsigned short int name_len =
115			le16_to_cpu(((struct smb2_create_req *)hdr)->NameLength);
116
117		if (((struct smb2_create_req *)hdr)->CreateContextsLength) {
118			*off = le32_to_cpu(((struct smb2_create_req *)
119				hdr)->CreateContextsOffset);
120			*len = le32_to_cpu(((struct smb2_create_req *)
121				hdr)->CreateContextsLength);
122			if (!name_len)
123				break;
124
125			if (name_off + name_len < (u64)*off + *len)
126				break;
127		}
128
129		*off = name_off;
130		*len = name_len;
131		break;
132	}
133	case SMB2_QUERY_INFO:
134		*off = max_t(unsigned int,
135			     le16_to_cpu(((struct smb2_query_info_req *)hdr)->InputBufferOffset),
136			     offsetof(struct smb2_query_info_req, Buffer));
137		*len = le32_to_cpu(((struct smb2_query_info_req *)hdr)->InputBufferLength);
138		break;
139	case SMB2_SET_INFO:
140		*off = max_t(unsigned int,
141			     le16_to_cpu(((struct smb2_set_info_req *)hdr)->BufferOffset),
142			     offsetof(struct smb2_set_info_req, Buffer));
143		*len = le32_to_cpu(((struct smb2_set_info_req *)hdr)->BufferLength);
144		break;
145	case SMB2_READ:
146		*off = le16_to_cpu(((struct smb2_read_req *)hdr)->ReadChannelInfoOffset);
147		*len = le16_to_cpu(((struct smb2_read_req *)hdr)->ReadChannelInfoLength);
148		break;
149	case SMB2_WRITE:
150		if (((struct smb2_write_req *)hdr)->DataOffset ||
151		    ((struct smb2_write_req *)hdr)->Length) {
152			*off = max_t(unsigned short int,
153				     le16_to_cpu(((struct smb2_write_req *)hdr)->DataOffset),
154				     offsetof(struct smb2_write_req, Buffer));
155			*len = le32_to_cpu(((struct smb2_write_req *)hdr)->Length);
156			break;
157		}
158
159		*off = le16_to_cpu(((struct smb2_write_req *)hdr)->WriteChannelInfoOffset);
160		*len = le16_to_cpu(((struct smb2_write_req *)hdr)->WriteChannelInfoLength);
161		break;
162	case SMB2_QUERY_DIRECTORY:
163		*off = max_t(unsigned short int,
164			     le16_to_cpu(((struct smb2_query_directory_req *)hdr)->FileNameOffset),
165			     offsetof(struct smb2_query_directory_req, Buffer));
166		*len = le16_to_cpu(((struct smb2_query_directory_req *)hdr)->FileNameLength);
167		break;
168	case SMB2_LOCK:
169	{
170		unsigned short lock_count;
171
172		lock_count = le16_to_cpu(((struct smb2_lock_req *)hdr)->LockCount);
173		if (lock_count > 0) {
174			*off = offsetof(struct smb2_lock_req, locks);
175			*len = sizeof(struct smb2_lock_element) * lock_count;
176		}
177		break;
178	}
179	case SMB2_IOCTL:
180		*off = max_t(unsigned int,
181			     le32_to_cpu(((struct smb2_ioctl_req *)hdr)->InputOffset),
182			     offsetof(struct smb2_ioctl_req, Buffer));
183		*len = le32_to_cpu(((struct smb2_ioctl_req *)hdr)->InputCount);
184		break;
185	default:
186		ksmbd_debug(SMB, "no length check for command\n");
187		break;
188	}
189
190	if (*off > 4096) {
191		ksmbd_debug(SMB, "offset %d too large\n", *off);
192		ret = -EINVAL;
193	} else if ((u64)*off + *len > MAX_STREAM_PROT_LEN) {
194		ksmbd_debug(SMB, "Request is larger than maximum stream protocol length(%u): %llu\n",
195			    MAX_STREAM_PROT_LEN, (u64)*off + *len);
196		ret = -EINVAL;
197	}
198
199	return ret;
200}
201
202/*
203 * Calculate the size of the SMB message based on the fixed header
204 * portion, the number of word parameters and the data portion of the message.
205 */
206static int smb2_calc_size(void *buf, unsigned int *len)
207{
208	struct smb2_pdu *pdu = (struct smb2_pdu *)buf;
209	struct smb2_hdr *hdr = &pdu->hdr;
210	unsigned int offset; /* the offset from the beginning of SMB to data area */
211	unsigned int data_length; /* the length of the variable length data area */
212	int ret;
213
214	/* Structure Size has already been checked to make sure it is 64 */
215	*len = le16_to_cpu(hdr->StructureSize);
216
217	/*
218	 * StructureSize2, ie length of fixed parameter area has already
219	 * been checked to make sure it is the correct length.
220	 */
221	*len += le16_to_cpu(pdu->StructureSize2);
222	/*
223	 * StructureSize2 of smb2_lock pdu is set to 48, indicating
224	 * the size of smb2 lock request with single smb2_lock_element
225	 * regardless of number of locks. Subtract single
226	 * smb2_lock_element for correct buffer size check.
227	 */
228	if (hdr->Command == SMB2_LOCK)
229		*len -= sizeof(struct smb2_lock_element);
230
231	if (has_smb2_data_area[le16_to_cpu(hdr->Command)] == false)
232		goto calc_size_exit;
233
234	ret = smb2_get_data_area_len(&offset, &data_length, hdr);
235	if (ret)
236		return ret;
237	ksmbd_debug(SMB, "SMB2 data length %u offset %u\n", data_length,
238		    offset);
239
240	if (data_length > 0) {
241		/*
242		 * Check to make sure that data area begins after fixed area,
243		 * Note that last byte of the fixed area is part of data area
244		 * for some commands, typically those with odd StructureSize,
245		 * so we must add one to the calculation.
246		 */
247		if (offset + 1 < *len) {
248			ksmbd_debug(SMB,
249				    "data area offset %d overlaps SMB2 header %u\n",
250				    offset + 1, *len);
251			return -EINVAL;
252		}
253
254		*len = offset + data_length;
255	}
256
257calc_size_exit:
258	ksmbd_debug(SMB, "SMB2 len %u\n", *len);
259	return 0;
260}
261
262static inline int smb2_query_info_req_len(struct smb2_query_info_req *h)
263{
264	return le32_to_cpu(h->InputBufferLength) +
265		le32_to_cpu(h->OutputBufferLength);
266}
267
268static inline int smb2_set_info_req_len(struct smb2_set_info_req *h)
269{
270	return le32_to_cpu(h->BufferLength);
271}
272
273static inline int smb2_read_req_len(struct smb2_read_req *h)
274{
275	return le32_to_cpu(h->Length);
276}
277
278static inline int smb2_write_req_len(struct smb2_write_req *h)
279{
280	return le32_to_cpu(h->Length);
281}
282
283static inline int smb2_query_dir_req_len(struct smb2_query_directory_req *h)
284{
285	return le32_to_cpu(h->OutputBufferLength);
286}
287
288static inline int smb2_ioctl_req_len(struct smb2_ioctl_req *h)
289{
290	return le32_to_cpu(h->InputCount) +
291		le32_to_cpu(h->OutputCount);
292}
293
294static inline int smb2_ioctl_resp_len(struct smb2_ioctl_req *h)
295{
296	return le32_to_cpu(h->MaxInputResponse) +
297		le32_to_cpu(h->MaxOutputResponse);
298}
299
300static int smb2_validate_credit_charge(struct ksmbd_conn *conn,
301				       struct smb2_hdr *hdr)
302{
303	unsigned int req_len = 0, expect_resp_len = 0, calc_credit_num, max_len;
304	unsigned short credit_charge = le16_to_cpu(hdr->CreditCharge);
305	void *__hdr = hdr;
306	int ret = 0;
307
308	switch (hdr->Command) {
309	case SMB2_QUERY_INFO:
310		req_len = smb2_query_info_req_len(__hdr);
311		break;
312	case SMB2_SET_INFO:
313		req_len = smb2_set_info_req_len(__hdr);
314		break;
315	case SMB2_READ:
316		req_len = smb2_read_req_len(__hdr);
317		break;
318	case SMB2_WRITE:
319		req_len = smb2_write_req_len(__hdr);
320		break;
321	case SMB2_QUERY_DIRECTORY:
322		req_len = smb2_query_dir_req_len(__hdr);
323		break;
324	case SMB2_IOCTL:
325		req_len = smb2_ioctl_req_len(__hdr);
326		expect_resp_len = smb2_ioctl_resp_len(__hdr);
327		break;
328	case SMB2_CANCEL:
329		return 0;
330	default:
331		req_len = 1;
332		break;
333	}
334
335	credit_charge = max_t(unsigned short, credit_charge, 1);
336	max_len = max_t(unsigned int, req_len, expect_resp_len);
337	calc_credit_num = DIV_ROUND_UP(max_len, SMB2_MAX_BUFFER_SIZE);
338
339	if (credit_charge < calc_credit_num) {
340		ksmbd_debug(SMB, "Insufficient credit charge, given: %d, needed: %d\n",
341			    credit_charge, calc_credit_num);
342		return 1;
343	} else if (credit_charge > conn->vals->max_credits) {
344		ksmbd_debug(SMB, "Too large credit charge: %d\n", credit_charge);
345		return 1;
346	}
347
348	spin_lock(&conn->credits_lock);
349	if (credit_charge > conn->total_credits) {
350		ksmbd_debug(SMB, "Insufficient credits granted, given: %u, granted: %u\n",
351			    credit_charge, conn->total_credits);
352		ret = 1;
353	}
354
355	if ((u64)conn->outstanding_credits + credit_charge > conn->total_credits) {
356		ksmbd_debug(SMB, "Limits exceeding the maximum allowable outstanding requests, given : %u, pending : %u\n",
357			    credit_charge, conn->outstanding_credits);
358		ret = 1;
359	} else
360		conn->outstanding_credits += credit_charge;
361
362	spin_unlock(&conn->credits_lock);
363
364	return ret;
365}
366
367int ksmbd_smb2_check_message(struct ksmbd_work *work)
368{
369	struct smb2_pdu *pdu = ksmbd_req_buf_next(work);
370	struct smb2_hdr *hdr = &pdu->hdr;
371	int command;
372	__u32 clc_len;  /* calculated length */
373	__u32 len = get_rfc1002_len(work->request_buf);
374	__u32 req_struct_size, next_cmd = le32_to_cpu(hdr->NextCommand);
375
376	if ((u64)work->next_smb2_rcv_hdr_off + next_cmd > len) {
377		pr_err("next command(%u) offset exceeds smb msg size\n",
378				next_cmd);
379		return 1;
380	}
381
382	if (next_cmd > 0)
383		len = next_cmd;
384	else if (work->next_smb2_rcv_hdr_off)
385		len -= work->next_smb2_rcv_hdr_off;
386
387	if (check_smb2_hdr(hdr))
388		return 1;
389
390	if (hdr->StructureSize != SMB2_HEADER_STRUCTURE_SIZE) {
391		ksmbd_debug(SMB, "Illegal structure size %u\n",
392			    le16_to_cpu(hdr->StructureSize));
393		return 1;
394	}
395
396	command = le16_to_cpu(hdr->Command);
397	if (command >= NUMBER_OF_SMB2_COMMANDS) {
398		ksmbd_debug(SMB, "Illegal SMB2 command %d\n", command);
399		return 1;
400	}
401
402	if (smb2_req_struct_sizes[command] != pdu->StructureSize2) {
403		if (!(command == SMB2_OPLOCK_BREAK_HE &&
404		    (le16_to_cpu(pdu->StructureSize2) == OP_BREAK_STRUCT_SIZE_20 ||
405		    le16_to_cpu(pdu->StructureSize2) == OP_BREAK_STRUCT_SIZE_21))) {
406			/* special case for SMB2.1 lease break message */
407			ksmbd_debug(SMB,
408				"Illegal request size %u for command %d\n",
409				le16_to_cpu(pdu->StructureSize2), command);
410			return 1;
411		}
412	}
413
414	req_struct_size = le16_to_cpu(pdu->StructureSize2) +
415		__SMB2_HEADER_STRUCTURE_SIZE;
416	if (command == SMB2_LOCK_HE)
417		req_struct_size -= sizeof(struct smb2_lock_element);
418
419	if (req_struct_size > len + 1)
420		return 1;
421
422	if (smb2_calc_size(hdr, &clc_len))
423		return 1;
424
425	if (len != clc_len) {
426		/* client can return one byte more due to implied bcc[0] */
427		if (clc_len == len + 1)
428			goto validate_credit;
429
430		/*
431		 * Some windows servers (win2016) will pad also the final
432		 * PDU in a compound to 8 bytes.
433		 */
434		if (ALIGN(clc_len, 8) == len)
435			goto validate_credit;
436
437		/*
438		 * SMB2 NEGOTIATE request will be validated when message
439		 * handling proceeds.
440		 */
441		if (command == SMB2_NEGOTIATE_HE)
442			goto validate_credit;
443
444		/*
445		 * Allow a message that padded to 8byte boundary.
446		 * Linux 4.19.217 with smb 3.0.2 are sometimes
447		 * sending messages where the cls_len is exactly
448		 * 8 bytes less than len.
449		 */
450		if (clc_len < len && (len - clc_len) <= 8)
451			goto validate_credit;
452
453		pr_err_ratelimited(
454			    "cli req too short, len %d not %d. cmd:%d mid:%llu\n",
455			    len, clc_len, command,
456			    le64_to_cpu(hdr->MessageId));
457
458		return 1;
459	}
460
461validate_credit:
462	if ((work->conn->vals->req_capabilities & SMB2_GLOBAL_CAP_LARGE_MTU) &&
463	    smb2_validate_credit_charge(work->conn, hdr))
464		return 1;
465
466	return 0;
467}
468
469int smb2_negotiate_request(struct ksmbd_work *work)
470{
471	return ksmbd_smb_negotiate_common(work, SMB2_NEGOTIATE_HE);
472}