fs/smb/server/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 "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 = 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  */
 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
 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
 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
 274 static inline int smb2_read_req_len(struct smb2_read_req *h)
 275 {
 276         return le32_to_cpu(h->Length);
 277 }
 278
 279 static inline int smb2_write_req_len(struct smb2_write_req *h)
 280 {
 281         return le32_to_cpu(h->Length);
 282 }
 283
 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
 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
 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
 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
 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
 470 int smb2_negotiate_request(struct ksmbd_work *work)
 471 {
 472         return ksmbd_smb_negotiate_common(work, SMB2_NEGOTIATE_HE);
 473 }