Quelle  smb2misc.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *   Copyright (C) 2016 Namjae Jeon <linkinjeon@kernel.org>
 *   Copyright (C) 2018 Samsung Electronics Co., Ltd.
 */

#include "glob.h"
#include "nterr.h"
#include "smb_common.h"
#include "../common/smb2status.h"
#include "mgmt/user_session.h"
#include "connection.h"

static int check_smb2_hdr(struct smb2_hdr *hdr)
{
 /*
 * Make sure that this really is an SMB, that it is a response.
 */
 if (hdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
  return 1;
 return 0;
}

/*
 *  The following table defines the expected "StructureSize" of SMB2 requests
 *  in order by SMB2 command.  This is similar to "wct" in SMB/CIFS requests.
 *
 *  Note that commands are defined in smb2pdu.h in le16 but the array below is
 *  indexed by command in host byte order
 */
static const __le16 smb2_req_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = {
 /* SMB2_NEGOTIATE */ cpu_to_le16(36),
 /* SMB2_SESSION_SETUP */ cpu_to_le16(25),
 /* SMB2_LOGOFF */ cpu_to_le16(4),
 /* SMB2_TREE_CONNECT */ cpu_to_le16(9),
 /* SMB2_TREE_DISCONNECT */ cpu_to_le16(4),
 /* SMB2_CREATE */ cpu_to_le16(57),
 /* SMB2_CLOSE */ cpu_to_le16(24),
 /* SMB2_FLUSH */ cpu_to_le16(24),
 /* SMB2_READ */ cpu_to_le16(49),
 /* SMB2_WRITE */ cpu_to_le16(49),
 /* SMB2_LOCK */ cpu_to_le16(48),
 /* SMB2_IOCTL */ cpu_to_le16(57),
 /* SMB2_CANCEL */ cpu_to_le16(4),
 /* SMB2_ECHO */ cpu_to_le16(4),
 /* SMB2_QUERY_DIRECTORY */ cpu_to_le16(33),
 /* SMB2_CHANGE_NOTIFY */ cpu_to_le16(32),
 /* SMB2_QUERY_INFO */ cpu_to_le16(41),
 /* SMB2_SET_INFO */ cpu_to_le16(33),
 /* use 44 for lease break */
 /* SMB2_OPLOCK_BREAK */ cpu_to_le16(36)
};

/*
 * The size of the variable area depends on the offset and length fields
 * located in different fields for various SMB2 requests. SMB2 requests
 * with no variable length info, show an offset of zero for the offset field.
 */
static const bool has_smb2_data_area[NUMBER_OF_SMB2_COMMANDS] = {
 /* SMB2_NEGOTIATE */ true,
 /* SMB2_SESSION_SETUP */ true,
 /* SMB2_LOGOFF */ false,
 /* SMB2_TREE_CONNECT */ true,
 /* SMB2_TREE_DISCONNECT */ false,
 /* SMB2_CREATE */ true,
 /* SMB2_CLOSE */ false,
 /* SMB2_FLUSH */ false,
 /* SMB2_READ */ true,
 /* SMB2_WRITE */ true,
 /* SMB2_LOCK */ true,
 /* SMB2_IOCTL */ true,
 /* SMB2_CANCEL */ false, /* BB CHECK this not listed in documentation */
 /* SMB2_ECHO */ false,
 /* SMB2_QUERY_DIRECTORY */ true,
 /* SMB2_CHANGE_NOTIFY */ false,
 /* SMB2_QUERY_INFO */ true,
 /* SMB2_SET_INFO */ true,
 /* SMB2_OPLOCK_BREAK */ false
};

/*
 * Set length of the data area and the offset to arguments.
 * if they are invalid, return error.
 */
static int smb2_get_data_area_len(unsigned int *off, unsigned int *len,
      struct smb2_hdr *hdr)
{
 int ret = 0;

 *off = 0;
 *len = 0;

 /*
 * Following commands have data areas so we have to get the location
 * of the data buffer offset and data buffer length for the particular
 * command.
 */
 switch (hdr->Command) {
 case SMB2_SESSION_SETUP:
  *off = le16_to_cpu(((struct smb2_sess_setup_req *)hdr)->SecurityBufferOffset);
  *len = le16_to_cpu(((struct smb2_sess_setup_req *)hdr)->SecurityBufferLength);
  break;
 case SMB2_TREE_CONNECT:
  *off = max_t(unsigned short int,
        le16_to_cpu(((struct smb2_tree_connect_req *)hdr)->PathOffset),
        offsetof(struct smb2_tree_connect_req, Buffer));
  *len = le16_to_cpu(((struct smb2_tree_connect_req *)hdr)->PathLength);
  break;
 case SMB2_CREATE:
 {
  unsigned short int name_off =
   max_t(unsigned short int,
         le16_to_cpu(((struct smb2_create_req *)hdr)->NameOffset),
         offsetof(struct smb2_create_req, Buffer));
  unsigned short int name_len =
   le16_to_cpu(((struct smb2_create_req *)hdr)->NameLength);

  if (((struct smb2_create_req *)hdr)->CreateContextsLength) {
   *off = le32_to_cpu(((struct smb2_create_req *)
    hdr)->CreateContextsOffset);
   *len = le32_to_cpu(((struct smb2_create_req *)
    hdr)->CreateContextsLength);
   if (!name_len)
    break;

   if (name_off + name_len < (u64)*off + *len)
    break;
  }

  *off = name_off;
  *len = name_len;
  break;
 }
 case SMB2_QUERY_INFO:
  *off = max_t(unsigned int,
        le16_to_cpu(((struct smb2_query_info_req *)hdr)->InputBufferOffset),
        offsetof(struct smb2_query_info_req, Buffer));
  *len = le32_to_cpu(((struct smb2_query_info_req *)hdr)->InputBufferLength);
  break;
 case SMB2_SET_INFO:
  *off = max_t(unsigned int,
        le16_to_cpu(((struct smb2_set_info_req *)hdr)->BufferOffset),
        offsetof(struct smb2_set_info_req, Buffer));
  *len = le32_to_cpu(((struct smb2_set_info_req *)hdr)->BufferLength);
  break;
 case SMB2_READ:
  *off = le16_to_cpu(((struct smb2_read_req *)hdr)->ReadChannelInfoOffset);
  *len = le16_to_cpu(((struct smb2_read_req *)hdr)->ReadChannelInfoLength);
  break;
 case SMB2_WRITE:
  if (((struct smb2_write_req *)hdr)->DataOffset ||
      ((struct smb2_write_req *)hdr)->Length) {
   *off = max_t(unsigned short int,
         le16_to_cpu(((struct smb2_write_req *)hdr)->DataOffset),
         offsetof(struct smb2_write_req, Buffer));
   *len = le32_to_cpu(((struct smb2_write_req *)hdr)->Length);
   break;
  }

  *off = le16_to_cpu(((struct smb2_write_req *)hdr)->WriteChannelInfoOffset);
  *len = le16_to_cpu(((struct smb2_write_req *)hdr)->WriteChannelInfoLength);
  break;
 case SMB2_QUERY_DIRECTORY:
  *off = max_t(unsigned short int,
        le16_to_cpu(((struct smb2_query_directory_req *)hdr)->FileNameOffset),
        offsetof(struct smb2_query_directory_req, Buffer));
  *len = le16_to_cpu(((struct smb2_query_directory_req *)hdr)->FileNameLength);
  break;
 case SMB2_LOCK:
 {
  unsigned short lock_count;

  lock_count = le16_to_cpu(((struct smb2_lock_req *)hdr)->LockCount);
  if (lock_count > 0) {
   *off = offsetof(struct smb2_lock_req, locks);
   *len = sizeof(struct smb2_lock_element) * lock_count;
  }
  break;
 }
 case SMB2_IOCTL:
  *off = max_t(unsigned int,
        le32_to_cpu(((struct smb2_ioctl_req *)hdr)->InputOffset),
        offsetof(struct smb2_ioctl_req, Buffer));
  *len = le32_to_cpu(((struct smb2_ioctl_req *)hdr)->InputCount);
  break;
 default:
  ksmbd_debug(SMB, "no length check for command\n");
  break;
 }

 if (*off > 4096) {
  ksmbd_debug(SMB, "offset %d too large\n", *off);
  ret = -EINVAL;
 } else if ((u64)*off + *len > MAX_STREAM_PROT_LEN) {
  ksmbd_debug(SMB, "Request is larger than maximum stream protocol length(%u): %llu\n",
       MAX_STREAM_PROT_LEN, (u64)*off + *len);
  ret = -EINVAL;
 }

 return ret;
}

/*
 * Calculate the size of the SMB message based on the fixed header
 * portion, the number of word parameters and the data portion of the message.
 */
static int smb2_calc_size(void *buf, unsigned int *len)
{
 struct smb2_pdu *pdu = (struct smb2_pdu *)buf;
 struct smb2_hdr *hdr = &pdu->hdr;
 unsigned int offset; /* the offset from the beginning of SMB to data area */
 unsigned int data_length; /* the length of the variable length data area */
 int ret;

 /* Structure Size has already been checked to make sure it is 64 */
 *len = le16_to_cpu(hdr->StructureSize);

 /*
 * StructureSize2, ie length of fixed parameter area has already
 * been checked to make sure it is the correct length.
 */
 *len += le16_to_cpu(pdu->StructureSize2);
 /*
 * StructureSize2 of smb2_lock pdu is set to 48, indicating
 * the size of smb2 lock request with single smb2_lock_element
 * regardless of number of locks. Subtract single
 * smb2_lock_element for correct buffer size check.
 */
 if (hdr->Command == SMB2_LOCK)
  *len -= sizeof(struct smb2_lock_element);

 if (has_smb2_data_area[le16_to_cpu(hdr->Command)] == false)
  goto calc_size_exit;

 ret = smb2_get_data_area_len(&offset, &data_length, hdr);
 if (ret)
  return ret;
 ksmbd_debug(SMB, "SMB2 data length %u offset %u\n", data_length,
      offset);

 if (data_length > 0) {
  /*
 * Check to make sure that data area begins after fixed area,
 * Note that last byte of the fixed area is part of data area
 * for some commands, typically those with odd StructureSize,
 * so we must add one to the calculation.
 */
  if (offset + 1 < *len) {
   ksmbd_debug(SMB,
        "data area offset %d overlaps SMB2 header %u\n",
        offset + 1, *len);
   return -EINVAL;
  }

  *len = offset + data_length;
 }

calc_size_exit:
 ksmbd_debug(SMB, "SMB2 len %u\n", *len);
 return 0;
}

static inline int smb2_query_info_req_len(struct smb2_query_info_req *h)
{
 return le32_to_cpu(h->InputBufferLength) +
  le32_to_cpu(h->OutputBufferLength);
}

static inline int smb2_set_info_req_len(struct smb2_set_info_req *h)
{
 return le32_to_cpu(h->BufferLength);
}

static inline int smb2_read_req_len(struct smb2_read_req *h)
{
 return le32_to_cpu(h->Length);
}

static inline int smb2_write_req_len(struct smb2_write_req *h)
{
 return le32_to_cpu(h->Length);
}

static inline int smb2_query_dir_req_len(struct smb2_query_directory_req *h)
{
 return le32_to_cpu(h->OutputBufferLength);
}

static inline int smb2_ioctl_req_len(struct smb2_ioctl_req *h)
{
 return le32_to_cpu(h->InputCount) +
  le32_to_cpu(h->OutputCount);
}

static inline int smb2_ioctl_resp_len(struct smb2_ioctl_req *h)
{
 return le32_to_cpu(h->MaxInputResponse) +
  le32_to_cpu(h->MaxOutputResponse);
}

static int smb2_validate_credit_charge(struct ksmbd_conn *conn,
           struct smb2_hdr *hdr)
{
 unsigned int req_len = 0, expect_resp_len = 0, calc_credit_num, max_len;
 unsigned short credit_charge = le16_to_cpu(hdr->CreditCharge);
 void *__hdr = hdr;
 int ret = 0;

 switch (hdr->Command) {
 case SMB2_QUERY_INFO:
  req_len = smb2_query_info_req_len(__hdr);
  break;
 case SMB2_SET_INFO:
  req_len = smb2_set_info_req_len(__hdr);
  break;
 case SMB2_READ:
  req_len = smb2_read_req_len(__hdr);
  break;
 case SMB2_WRITE:
  req_len = smb2_write_req_len(__hdr);
  break;
 case SMB2_QUERY_DIRECTORY:
  req_len = smb2_query_dir_req_len(__hdr);
  break;
 case SMB2_IOCTL:
  req_len = smb2_ioctl_req_len(__hdr);
  expect_resp_len = smb2_ioctl_resp_len(__hdr);
  break;
 case SMB2_CANCEL:
  return 0;
 default:
  req_len = 1;
  break;
 }

 credit_charge = max_t(unsigned short, credit_charge, 1);
 max_len = max_t(unsigned int, req_len, expect_resp_len);
 calc_credit_num = DIV_ROUND_UP(max_len, SMB2_MAX_BUFFER_SIZE);

 if (credit_charge < calc_credit_num) {
  ksmbd_debug(SMB, "Insufficient credit charge, given: %d, needed: %d\n",
       credit_charge, calc_credit_num);
  return 1;
 } else if (credit_charge > conn->vals->max_credits) {
  ksmbd_debug(SMB, "Too large credit charge: %d\n", credit_charge);
  return 1;
 }

 spin_lock(&conn->credits_lock);
 if (credit_charge > conn->total_credits) {
  ksmbd_debug(SMB, "Insufficient credits granted, given: %u, granted: %u\n",
       credit_charge, conn->total_credits);
  ret = 1;
 }

 if ((u64)conn->outstanding_credits + credit_charge > conn->total_credits) {
  ksmbd_debug(SMB, "Limits exceeding the maximum allowable outstanding requests, given : %u, pending : %u\n",
       credit_charge, conn->outstanding_credits);
  ret = 1;
 } else
  conn->outstanding_credits += credit_charge;

 spin_unlock(&conn->credits_lock);

 return ret;
}

int ksmbd_smb2_check_message(struct ksmbd_work *work)
{
 struct smb2_pdu *pdu = ksmbd_req_buf_next(work);
 struct smb2_hdr *hdr = &pdu->hdr;
 int command;
 __u32 clc_len;  /* calculated length */
 __u32 len = get_rfc1002_len(work->request_buf);
 __u32 req_struct_size, next_cmd = le32_to_cpu(hdr->NextCommand);

 if ((u64)work->next_smb2_rcv_hdr_off + next_cmd > len) {
  pr_err("next command(%u) offset exceeds smb msg size\n",
    next_cmd);
  return 1;
 }

 if (next_cmd > 0)
  len = next_cmd;
 else if (work->next_smb2_rcv_hdr_off)
  len -= work->next_smb2_rcv_hdr_off;

 if (check_smb2_hdr(hdr))
  return 1;

 if (hdr->StructureSize != SMB2_HEADER_STRUCTURE_SIZE) {
  ksmbd_debug(SMB, "Illegal structure size %u\n",
       le16_to_cpu(hdr->StructureSize));
  return 1;
 }

 command = le16_to_cpu(hdr->Command);
 if (command >= NUMBER_OF_SMB2_COMMANDS) {
  ksmbd_debug(SMB, "Illegal SMB2 command %d\n", command);
  return 1;
 }

 if (smb2_req_struct_sizes[command] != pdu->StructureSize2) {
  if (!(command == SMB2_OPLOCK_BREAK_HE &&
      (le16_to_cpu(pdu->StructureSize2) == OP_BREAK_STRUCT_SIZE_20 ||
      le16_to_cpu(pdu->StructureSize2) == OP_BREAK_STRUCT_SIZE_21))) {
   /* special case for SMB2.1 lease break message */
   ksmbd_debug(SMB,
    "Illegal request size %u for command %d\n",
    le16_to_cpu(pdu->StructureSize2), command);
   return 1;
  }
 }

 req_struct_size = le16_to_cpu(pdu->StructureSize2) +
  __SMB2_HEADER_STRUCTURE_SIZE;
 if (command == SMB2_LOCK_HE)
  req_struct_size -= sizeof(struct smb2_lock_element);

 if (req_struct_size > len + 1)
  return 1;

 if (smb2_calc_size(hdr, &clc_len))
  return 1;

 if (len != clc_len) {
  /* client can return one byte more due to implied bcc[0] */
  if (clc_len == len + 1)
   goto validate_credit;

  /*
 * Some windows servers (win2016) will pad also the final
 * PDU in a compound to 8 bytes.
 */
  if (ALIGN(clc_len, 8) == len)
   goto validate_credit;

  /*
 * SMB2 NEGOTIATE request will be validated when message
 * handling proceeds.
 */
  if (command == SMB2_NEGOTIATE_HE)
   goto validate_credit;

  /*
 * Allow a message that padded to 8byte boundary.
 * Linux 4.19.217 with smb 3.0.2 are sometimes
 * sending messages where the cls_len is exactly
 * 8 bytes less than len.
 */
  if (clc_len < len && (len - clc_len) <= 8)
   goto validate_credit;

  pr_err_ratelimited(
       "cli req too short, len %d not %d. cmd:%d mid:%llu\n",
       len, clc_len, command,
       le64_to_cpu(hdr->MessageId));

  return 1;
 }

validate_credit:
 if ((work->conn->vals->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU) &&
     smb2_validate_credit_charge(work->conn, hdr))
  return 1;

 return 0;
}

int smb2_negotiate_request(struct ksmbd_work *work)
{
 return ksmbd_smb_negotiate_common(work, SMB2_NEGOTIATE_HE);
}