xref: /openbmc/linux/fs/smb/server/smb2misc.c (revision 2a598d0b)
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 
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  */
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 = le16_to_cpu(((struct smb2_tree_connect_req *)hdr)->PathOffset);
105 		*len = le16_to_cpu(((struct smb2_tree_connect_req *)hdr)->PathLength);
106 		break;
107 	case SMB2_CREATE:
108 	{
109 		if (((struct smb2_create_req *)hdr)->CreateContextsLength) {
110 			*off = le32_to_cpu(((struct smb2_create_req *)
111 				hdr)->CreateContextsOffset);
112 			*len = le32_to_cpu(((struct smb2_create_req *)
113 				hdr)->CreateContextsLength);
114 			break;
115 		}
116 
117 		*off = le16_to_cpu(((struct smb2_create_req *)hdr)->NameOffset);
118 		*len = le16_to_cpu(((struct smb2_create_req *)hdr)->NameLength);
119 		break;
120 	}
121 	case SMB2_QUERY_INFO:
122 		*off = le16_to_cpu(((struct smb2_query_info_req *)hdr)->InputBufferOffset);
123 		*len = le32_to_cpu(((struct smb2_query_info_req *)hdr)->InputBufferLength);
124 		break;
125 	case SMB2_SET_INFO:
126 		*off = le16_to_cpu(((struct smb2_set_info_req *)hdr)->BufferOffset);
127 		*len = le32_to_cpu(((struct smb2_set_info_req *)hdr)->BufferLength);
128 		break;
129 	case SMB2_READ:
130 		*off = le16_to_cpu(((struct smb2_read_req *)hdr)->ReadChannelInfoOffset);
131 		*len = le16_to_cpu(((struct smb2_read_req *)hdr)->ReadChannelInfoLength);
132 		break;
133 	case SMB2_WRITE:
134 		if (((struct smb2_write_req *)hdr)->DataOffset ||
135 		    ((struct smb2_write_req *)hdr)->Length) {
136 			*off = max_t(unsigned int,
137 				     le16_to_cpu(((struct smb2_write_req *)hdr)->DataOffset),
138 				     offsetof(struct smb2_write_req, Buffer));
139 			*len = le32_to_cpu(((struct smb2_write_req *)hdr)->Length);
140 			break;
141 		}
142 
143 		*off = le16_to_cpu(((struct smb2_write_req *)hdr)->WriteChannelInfoOffset);
144 		*len = le16_to_cpu(((struct smb2_write_req *)hdr)->WriteChannelInfoLength);
145 		break;
146 	case SMB2_QUERY_DIRECTORY:
147 		*off = le16_to_cpu(((struct smb2_query_directory_req *)hdr)->FileNameOffset);
148 		*len = le16_to_cpu(((struct smb2_query_directory_req *)hdr)->FileNameLength);
149 		break;
150 	case SMB2_LOCK:
151 	{
152 		unsigned short lock_count;
153 
154 		lock_count = le16_to_cpu(((struct smb2_lock_req *)hdr)->LockCount);
155 		if (lock_count > 0) {
156 			*off = offsetof(struct smb2_lock_req, locks);
157 			*len = sizeof(struct smb2_lock_element) * lock_count;
158 		}
159 		break;
160 	}
161 	case SMB2_IOCTL:
162 		*off = le32_to_cpu(((struct smb2_ioctl_req *)hdr)->InputOffset);
163 		*len = le32_to_cpu(((struct smb2_ioctl_req *)hdr)->InputCount);
164 		break;
165 	default:
166 		ksmbd_debug(SMB, "no length check for command\n");
167 		break;
168 	}
169 
170 	if (*off > 4096) {
171 		ksmbd_debug(SMB, "offset %d too large\n", *off);
172 		ret = -EINVAL;
173 	} else if ((u64)*off + *len > MAX_STREAM_PROT_LEN) {
174 		ksmbd_debug(SMB, "Request is larger than maximum stream protocol length(%u): %llu\n",
175 			    MAX_STREAM_PROT_LEN, (u64)*off + *len);
176 		ret = -EINVAL;
177 	}
178 
179 	return ret;
180 }
181 
182 /*
183  * Calculate the size of the SMB message based on the fixed header
184  * portion, the number of word parameters and the data portion of the message.
185  */
186 static int smb2_calc_size(void *buf, unsigned int *len)
187 {
188 	struct smb2_pdu *pdu = (struct smb2_pdu *)buf;
189 	struct smb2_hdr *hdr = &pdu->hdr;
190 	unsigned int offset; /* the offset from the beginning of SMB to data area */
191 	unsigned int data_length; /* the length of the variable length data area */
192 	int ret;
193 
194 	/* Structure Size has already been checked to make sure it is 64 */
195 	*len = le16_to_cpu(hdr->StructureSize);
196 
197 	/*
198 	 * StructureSize2, ie length of fixed parameter area has already
199 	 * been checked to make sure it is the correct length.
200 	 */
201 	*len += le16_to_cpu(pdu->StructureSize2);
202 	/*
203 	 * StructureSize2 of smb2_lock pdu is set to 48, indicating
204 	 * the size of smb2 lock request with single smb2_lock_element
205 	 * regardless of number of locks. Subtract single
206 	 * smb2_lock_element for correct buffer size check.
207 	 */
208 	if (hdr->Command == SMB2_LOCK)
209 		*len -= sizeof(struct smb2_lock_element);
210 
211 	if (has_smb2_data_area[le16_to_cpu(hdr->Command)] == false)
212 		goto calc_size_exit;
213 
214 	ret = smb2_get_data_area_len(&offset, &data_length, hdr);
215 	if (ret)
216 		return ret;
217 	ksmbd_debug(SMB, "SMB2 data length %u offset %u\n", data_length,
218 		    offset);
219 
220 	if (data_length > 0) {
221 		/*
222 		 * Check to make sure that data area begins after fixed area,
223 		 * Note that last byte of the fixed area is part of data area
224 		 * for some commands, typically those with odd StructureSize,
225 		 * so we must add one to the calculation.
226 		 */
227 		if (offset + 1 < *len) {
228 			ksmbd_debug(SMB,
229 				    "data area offset %d overlaps SMB2 header %u\n",
230 				    offset + 1, *len);
231 			return -EINVAL;
232 		}
233 
234 		*len = offset + data_length;
235 	}
236 
237 calc_size_exit:
238 	ksmbd_debug(SMB, "SMB2 len %u\n", *len);
239 	return 0;
240 }
241 
242 static inline int smb2_query_info_req_len(struct smb2_query_info_req *h)
243 {
244 	return le32_to_cpu(h->InputBufferLength) +
245 		le32_to_cpu(h->OutputBufferLength);
246 }
247 
248 static inline int smb2_set_info_req_len(struct smb2_set_info_req *h)
249 {
250 	return le32_to_cpu(h->BufferLength);
251 }
252 
253 static inline int smb2_read_req_len(struct smb2_read_req *h)
254 {
255 	return le32_to_cpu(h->Length);
256 }
257 
258 static inline int smb2_write_req_len(struct smb2_write_req *h)
259 {
260 	return le32_to_cpu(h->Length);
261 }
262 
263 static inline int smb2_query_dir_req_len(struct smb2_query_directory_req *h)
264 {
265 	return le32_to_cpu(h->OutputBufferLength);
266 }
267 
268 static inline int smb2_ioctl_req_len(struct smb2_ioctl_req *h)
269 {
270 	return le32_to_cpu(h->InputCount) +
271 		le32_to_cpu(h->OutputCount);
272 }
273 
274 static inline int smb2_ioctl_resp_len(struct smb2_ioctl_req *h)
275 {
276 	return le32_to_cpu(h->MaxInputResponse) +
277 		le32_to_cpu(h->MaxOutputResponse);
278 }
279 
280 static int smb2_validate_credit_charge(struct ksmbd_conn *conn,
281 				       struct smb2_hdr *hdr)
282 {
283 	unsigned int req_len = 0, expect_resp_len = 0, calc_credit_num, max_len;
284 	unsigned short credit_charge = le16_to_cpu(hdr->CreditCharge);
285 	void *__hdr = hdr;
286 	int ret = 0;
287 
288 	switch (hdr->Command) {
289 	case SMB2_QUERY_INFO:
290 		req_len = smb2_query_info_req_len(__hdr);
291 		break;
292 	case SMB2_SET_INFO:
293 		req_len = smb2_set_info_req_len(__hdr);
294 		break;
295 	case SMB2_READ:
296 		req_len = smb2_read_req_len(__hdr);
297 		break;
298 	case SMB2_WRITE:
299 		req_len = smb2_write_req_len(__hdr);
300 		break;
301 	case SMB2_QUERY_DIRECTORY:
302 		req_len = smb2_query_dir_req_len(__hdr);
303 		break;
304 	case SMB2_IOCTL:
305 		req_len = smb2_ioctl_req_len(__hdr);
306 		expect_resp_len = smb2_ioctl_resp_len(__hdr);
307 		break;
308 	case SMB2_CANCEL:
309 		return 0;
310 	default:
311 		req_len = 1;
312 		break;
313 	}
314 
315 	credit_charge = max_t(unsigned short, credit_charge, 1);
316 	max_len = max_t(unsigned int, req_len, expect_resp_len);
317 	calc_credit_num = DIV_ROUND_UP(max_len, SMB2_MAX_BUFFER_SIZE);
318 
319 	if (credit_charge < calc_credit_num) {
320 		ksmbd_debug(SMB, "Insufficient credit charge, given: %d, needed: %d\n",
321 			    credit_charge, calc_credit_num);
322 		return 1;
323 	} else if (credit_charge > conn->vals->max_credits) {
324 		ksmbd_debug(SMB, "Too large credit charge: %d\n", credit_charge);
325 		return 1;
326 	}
327 
328 	spin_lock(&conn->credits_lock);
329 	if (credit_charge > conn->total_credits) {
330 		ksmbd_debug(SMB, "Insufficient credits granted, given: %u, granted: %u\n",
331 			    credit_charge, conn->total_credits);
332 		ret = 1;
333 	}
334 
335 	if ((u64)conn->outstanding_credits + credit_charge > conn->total_credits) {
336 		ksmbd_debug(SMB, "Limits exceeding the maximum allowable outstanding requests, given : %u, pending : %u\n",
337 			    credit_charge, conn->outstanding_credits);
338 		ret = 1;
339 	} else
340 		conn->outstanding_credits += credit_charge;
341 
342 	spin_unlock(&conn->credits_lock);
343 
344 	return ret;
345 }
346 
347 int ksmbd_smb2_check_message(struct ksmbd_work *work)
348 {
349 	struct smb2_pdu *pdu = ksmbd_req_buf_next(work);
350 	struct smb2_hdr *hdr = &pdu->hdr;
351 	int command;
352 	__u32 clc_len;  /* calculated length */
353 	__u32 len = get_rfc1002_len(work->request_buf);
354 	__u32 req_struct_size, next_cmd = le32_to_cpu(hdr->NextCommand);
355 
356 	if ((u64)work->next_smb2_rcv_hdr_off + next_cmd > len) {
357 		pr_err("next command(%u) offset exceeds smb msg size\n",
358 				next_cmd);
359 		return 1;
360 	}
361 
362 	if (next_cmd > 0)
363 		len = next_cmd;
364 	else if (work->next_smb2_rcv_hdr_off)
365 		len -= work->next_smb2_rcv_hdr_off;
366 
367 	if (check_smb2_hdr(hdr))
368 		return 1;
369 
370 	if (hdr->StructureSize != SMB2_HEADER_STRUCTURE_SIZE) {
371 		ksmbd_debug(SMB, "Illegal structure size %u\n",
372 			    le16_to_cpu(hdr->StructureSize));
373 		return 1;
374 	}
375 
376 	command = le16_to_cpu(hdr->Command);
377 	if (command >= NUMBER_OF_SMB2_COMMANDS) {
378 		ksmbd_debug(SMB, "Illegal SMB2 command %d\n", command);
379 		return 1;
380 	}
381 
382 	if (smb2_req_struct_sizes[command] != pdu->StructureSize2) {
383 		if (command == SMB2_OPLOCK_BREAK_HE &&
384 		    le16_to_cpu(pdu->StructureSize2) != OP_BREAK_STRUCT_SIZE_20 &&
385 		    le16_to_cpu(pdu->StructureSize2) != OP_BREAK_STRUCT_SIZE_21) {
386 			/* special case for SMB2.1 lease break message */
387 			ksmbd_debug(SMB,
388 				    "Illegal request size %d for oplock break\n",
389 				    le16_to_cpu(pdu->StructureSize2));
390 			return 1;
391 		}
392 	}
393 
394 	req_struct_size = le16_to_cpu(pdu->StructureSize2) +
395 		__SMB2_HEADER_STRUCTURE_SIZE;
396 	if (command == SMB2_LOCK_HE)
397 		req_struct_size -= sizeof(struct smb2_lock_element);
398 
399 	if (req_struct_size > len + 1)
400 		return 1;
401 
402 	if (smb2_calc_size(hdr, &clc_len))
403 		return 1;
404 
405 	if (len != clc_len) {
406 		/* client can return one byte more due to implied bcc[0] */
407 		if (clc_len == len + 1)
408 			goto validate_credit;
409 
410 		/*
411 		 * Some windows servers (win2016) will pad also the final
412 		 * PDU in a compound to 8 bytes.
413 		 */
414 		if (ALIGN(clc_len, 8) == len)
415 			goto validate_credit;
416 
417 		/*
418 		 * SMB2 NEGOTIATE request will be validated when message
419 		 * handling proceeds.
420 		 */
421 		if (command == SMB2_NEGOTIATE_HE)
422 			goto validate_credit;
423 
424 		/*
425 		 * Allow a message that padded to 8byte boundary.
426 		 * Linux 4.19.217 with smb 3.0.2 are sometimes
427 		 * sending messages where the cls_len is exactly
428 		 * 8 bytes less than len.
429 		 */
430 		if (clc_len < len && (len - clc_len) <= 8)
431 			goto validate_credit;
432 
433 		pr_err_ratelimited(
434 			    "cli req too short, len %d not %d. cmd:%d mid:%llu\n",
435 			    len, clc_len, command,
436 			    le64_to_cpu(hdr->MessageId));
437 
438 		return 1;
439 	}
440 
441 validate_credit:
442 	if ((work->conn->vals->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU) &&
443 	    smb2_validate_credit_charge(work->conn, hdr)) {
444 		work->conn->ops->set_rsp_status(work, STATUS_INVALID_PARAMETER);
445 		return 1;
446 	}
447 
448 	return 0;
449 }
450 
451 int smb2_negotiate_request(struct ksmbd_work *work)
452 {
453 	return ksmbd_smb_negotiate_common(work, SMB2_NEGOTIATE_HE);
454 }
455