xref: /openbmc/linux/fs/smb/server/smb2misc.c (revision 39bdc419)
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 
check_smb2_hdr(struct smb2_hdr * hdr)14 static 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  */
31 static 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  */
59 static 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  */
smb2_get_data_area_len(unsigned int * off,unsigned int * len,struct smb2_hdr * hdr)85 static 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  */
smb2_calc_size(void * buf,unsigned int * len)207 static 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 
258 calc_size_exit:
259 	ksmbd_debug(SMB, "SMB2 len %u\n", *len);
260 	return 0;
261 }
262 
smb2_query_info_req_len(struct smb2_query_info_req * h)263 static 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 
smb2_set_info_req_len(struct smb2_set_info_req * h)269 static inline int smb2_set_info_req_len(struct smb2_set_info_req *h)
270 {
271 	return le32_to_cpu(h->BufferLength);
272 }
273 
smb2_read_req_len(struct smb2_read_req * h)274 static inline int smb2_read_req_len(struct smb2_read_req *h)
275 {
276 	return le32_to_cpu(h->Length);
277 }
278 
smb2_write_req_len(struct smb2_write_req * h)279 static inline int smb2_write_req_len(struct smb2_write_req *h)
280 {
281 	return le32_to_cpu(h->Length);
282 }
283 
smb2_query_dir_req_len(struct smb2_query_directory_req * h)284 static inline int smb2_query_dir_req_len(struct smb2_query_directory_req *h)
285 {
286 	return le32_to_cpu(h->OutputBufferLength);
287 }
288 
smb2_ioctl_req_len(struct smb2_ioctl_req * h)289 static 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 
smb2_ioctl_resp_len(struct smb2_ioctl_req * h)295 static 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 
smb2_validate_credit_charge(struct ksmbd_conn * conn,struct smb2_hdr * hdr)301 static 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 
ksmbd_smb2_check_message(struct ksmbd_work * work)368 int 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 
462 validate_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 
smb2_negotiate_request(struct ksmbd_work * work)470 int smb2_negotiate_request(struct ksmbd_work *work)
471 {
472 	return ksmbd_smb_negotiate_common(work, SMB2_NEGOTIATE_HE);
473 }
474