path: root/fs/cifs/smb2misc.c

/*
 *   fs/cifs/smb2misc.c
 *
 *   Copyright (C) International Business Machines  Corp., 2002,2011
 *                 Etersoft, 2012
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *              Pavel Shilovsky (pshilovsky@samba.org) 2012
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published
 *   by the Free Software Foundation; either version 2.1 of the License, or
 *   (at your option) any later version.
 *
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
#include <linux/ctype.h>
#include "smb2pdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "smb2proto.h"
#include "cifs_debug.h"
#include "cifs_unicode.h"
#include "smb2status.h"
#include "smb2glob.h"
#include "nterr.h"

static int
check_smb2_hdr(struct smb2_sync_hdr *shdr, __u64 mid)
{
	__u64 wire_mid = le64_to_cpu(shdr->MessageId);

	/*
	 * Make sure that this really is an SMB, that it is a response,
	 * and that the message ids match.
	 */
	if ((shdr->ProtocolId == SMB2_PROTO_NUMBER) &&
	    (mid == wire_mid)) {
		if (shdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
			return 0;
		else {
			/* only one valid case where server sends us request */
			if (shdr->Command == SMB2_OPLOCK_BREAK)
				return 0;
			else
				cifs_dbg(VFS, "Received Request not response\n");
		}
	} else { /* bad signature or mid */
		if (shdr->ProtocolId != SMB2_PROTO_NUMBER)
			cifs_dbg(VFS, "Bad protocol string signature header %x\n",
				 le32_to_cpu(shdr->ProtocolId));
		if (mid != wire_mid)
			cifs_dbg(VFS, "Mids do not match: %llu and %llu\n",
				 mid, wire_mid);
	}
	cifs_dbg(VFS, "Bad SMB detected. The Mid=%llu\n", wire_mid);
	return 1;
}

/*
 *  The following table defines the expected "StructureSize" of SMB2 responses
 *  in order by SMB2 command.  This is similar to "wct" in SMB/CIFS responses.
 *
 *  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_rsp_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = {
	/* SMB2_NEGOTIATE */ cpu_to_le16(65),
	/* SMB2_SESSION_SETUP */ cpu_to_le16(9),
	/* SMB2_LOGOFF */ cpu_to_le16(4),
	/* SMB2_TREE_CONNECT */ cpu_to_le16(16),
	/* SMB2_TREE_DISCONNECT */ cpu_to_le16(4),
	/* SMB2_CREATE */ cpu_to_le16(89),
	/* SMB2_CLOSE */ cpu_to_le16(60),
	/* SMB2_FLUSH */ cpu_to_le16(4),
	/* SMB2_READ */ cpu_to_le16(17),
	/* SMB2_WRITE */ cpu_to_le16(17),
	/* SMB2_LOCK */ cpu_to_le16(4),
	/* SMB2_IOCTL */ cpu_to_le16(49),
	/* BB CHECK this ... not listed in documentation */
	/* SMB2_CANCEL */ cpu_to_le16(0),
	/* SMB2_ECHO */ cpu_to_le16(4),
	/* SMB2_QUERY_DIRECTORY */ cpu_to_le16(9),
	/* SMB2_CHANGE_NOTIFY */ cpu_to_le16(9),
	/* SMB2_QUERY_INFO */ cpu_to_le16(9),
	/* SMB2_SET_INFO */ cpu_to_le16(2),
	/* BB FIXME can also be 44 for lease break */
	/* SMB2_OPLOCK_BREAK */ cpu_to_le16(24)
};

static __u32 get_neg_ctxt_len(struct smb2_sync_hdr *hdr, __u32 len,
			      __u32 non_ctxlen)
{
	__u16 neg_count;
	__u32 nc_offset, size_of_pad_before_neg_ctxts;
	struct smb2_negotiate_rsp *pneg_rsp = (struct smb2_negotiate_rsp *)hdr;

	/* Negotiate contexts are only valid for latest dialect SMB3.11 */
	neg_count = le16_to_cpu(pneg_rsp->NegotiateContextCount);
	if ((neg_count == 0) ||
	   (pneg_rsp->DialectRevision != cpu_to_le16(SMB311_PROT_ID)))
		return 0;

	/* Make sure that negotiate contexts start after gss security blob */
	nc_offset = le32_to_cpu(pneg_rsp->NegotiateContextOffset);
	if (nc_offset < non_ctxlen) {
		pr_warn_once("Invalid negotiate context offset\n");
		return 0;
	}
	size_of_pad_before_neg_ctxts = nc_offset - non_ctxlen;

	/* Verify that at least minimal negotiate contexts fit within frame */
	if (len < nc_offset + (neg_count * sizeof(struct smb2_neg_context))) {
		pr_warn_once("negotiate context goes beyond end\n");
		return 0;
	}

	cifs_dbg(FYI, "length of negcontexts %d pad %d\n",
		len - nc_offset, size_of_pad_before_neg_ctxts);

	/* length of negcontexts including pad from end of sec blob to them */
	return (len - nc_offset) + size_of_pad_before_neg_ctxts;
}

int
smb2_check_message(char *buf, unsigned int len, struct TCP_Server_Info *srvr)
{
	struct smb2_sync_hdr *shdr = (struct smb2_sync_hdr *)buf;
	struct smb2_sync_pdu *pdu = (struct smb2_sync_pdu *)shdr;
	__u64 mid;
	__u32 clc_len;  /* calculated length */
	int command;
	int pdu_size = sizeof(struct smb2_sync_pdu);
	int hdr_size = sizeof(struct smb2_sync_hdr);

	/*
	 * Add function to do table lookup of StructureSize by command
	 * ie Validate the wct via smb2_struct_sizes table above
	 */
	if (shdr->ProtocolId == SMB2_TRANSFORM_PROTO_NUM) {
		struct smb2_transform_hdr *thdr =
			(struct smb2_transform_hdr *)buf;
		struct cifs_ses *ses = NULL;
		struct list_head *tmp;

		/* decrypt frame now that it is completely read in */
		spin_lock(&cifs_tcp_ses_lock);
		list_for_each(tmp, &srvr->smb_ses_list) {
			ses = list_entry(tmp, struct cifs_ses, smb_ses_list);
			if (ses->Suid == thdr->SessionId)
				break;

			ses = NULL;
		}
		spin_unlock(&cifs_tcp_ses_lock);
		if (ses == NULL) {
			cifs_dbg(VFS, "no decryption - session id not found\n");
			return 1;
		}
	}

	mid = le64_to_cpu(shdr->MessageId);
	if (len < pdu_size) {
		if ((len >= hdr_size)
		    && (shdr->Status != 0)) {
			pdu->StructureSize2 = 0;
			/*
			 * As with SMB/CIFS, on some error cases servers may
			 * not return wct properly
			 */
			return 0;
		} else {
			cifs_dbg(VFS, "Length less than SMB header size\n");
		}
		return 1;
	}
	if (len > CIFSMaxBufSize + MAX_SMB2_HDR_SIZE) {
		cifs_dbg(VFS, "SMB length greater than maximum, mid=%llu\n",
			 mid);
		return 1;
	}

	if (check_smb2_hdr(shdr, mid))
		return 1;

	if (shdr->StructureSize != SMB2_HEADER_STRUCTURE_SIZE) {
		cifs_dbg(VFS, "Invalid structure size %u\n",
			 le16_to_cpu(shdr->StructureSize));
		return 1;
	}

	command = le16_to_cpu(shdr->Command);
	if (command >= NUMBER_OF_SMB2_COMMANDS) {
		cifs_dbg(VFS, "Invalid SMB2 command %d\n", command);
		return 1;
	}

	if (smb2_rsp_struct_sizes[command] != pdu->StructureSize2) {
		if (command != SMB2_OPLOCK_BREAK_HE && (shdr->Status == 0 ||
		    pdu->StructureSize2 != SMB2_ERROR_STRUCTURE_SIZE2)) {
			/* error packets have 9 byte structure size */
			cifs_dbg(VFS, "Invalid response size %u for command %d\n",
				 le16_to_cpu(pdu->StructureSize2), command);
			return 1;
		} else if (command == SMB2_OPLOCK_BREAK_HE
			   && (shdr->Status == 0)
			   && (le16_to_cpu(pdu->StructureSize2) != 44)
			   && (le16_to_cpu(pdu->StructureSize2) != 36)) {
			/* special case for SMB2.1 lease break message */
			cifs_dbg(VFS, "Invalid response size %d for oplock break\n",
				 le16_to_cpu(pdu->StructureSize2));
			return 1;
		}
	}

	clc_len = smb2_calc_size(buf, srvr);

	if (shdr->Command == SMB2_NEGOTIATE)
		clc_len += get_neg_ctxt_len(shdr, len, clc_len);

	if (len != clc_len) {
		cifs_dbg(FYI, "Calculated size %u length %u mismatch mid %llu\n",
			 clc_len, len, mid);
		/* create failed on symlink */
		if (command == SMB2_CREATE_HE &&
		    shdr->Status == STATUS_STOPPED_ON_SYMLINK)
			return 0;
		/* Windows 7 server returns 24 bytes more */
		if (clc_len + 24 == len && command == SMB2_OPLOCK_BREAK_HE)
			return 0;
		/* server can return one byte more due to implied bcc[0] */
		if (clc_len == len + 1)
			return 0;

		/*
		 * Some windows servers (win2016) will pad also the final
		 * PDU in a compound to 8 bytes.
		 */
		if (((clc_len + 7) & ~7) == len)
			return 0;

		/*
		 * MacOS server pads after SMB2.1 write response with 3 bytes
		 * of junk. Other servers match RFC1001 len to actual
		 * SMB2/SMB3 frame length (header + smb2 response specific data)
		 * Some windows servers also pad up to 8 bytes when compounding.
		 */
		if (clc_len < len)
			return 0;

		pr_warn_once(
			"srv rsp too short, len %d not %d. cmd:%d mid:%llu\n",
			len, clc_len, command, mid);

		return 1;
	}
	return 0;
}

/*
 * The size of the variable area depends on the offset and length fields
 * located in different fields for various SMB2 responses. SMB2 responses
 * 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 */	false,
	/* SMB2_TREE_DISCONNECT */ false,
	/* SMB2_CREATE */ true,
	/* SMB2_CLOSE */ false,
	/* SMB2_FLUSH */ false,
	/* SMB2_READ */	true,
	/* SMB2_WRITE */ false,
	/* SMB2_LOCK */	false,
	/* SMB2_IOCTL */ true,
	/* SMB2_CANCEL */ false, /* BB CHECK this not listed in documentation */
	/* SMB2_ECHO */ false,
	/* SMB2_QUERY_DIRECTORY */ true,
	/* SMB2_CHANGE_NOTIFY */ true,
	/* SMB2_QUERY_INFO */ true,
	/* SMB2_SET_INFO */ false,
	/* SMB2_OPLOCK_BREAK */ false
};

/*
 * Returns the pointer to the beginning of the data area. Length of the data
 * area and the offset to it (from the beginning of the smb are also returned.
 */
char *
smb2_get_data_area_len(int *off, int *len, struct smb2_sync_hdr *shdr)
{
	*off = 0;
	*len = 0;

	/* error responses do not have data area */
	if (shdr->Status && shdr->Status != STATUS_MORE_PROCESSING_REQUIRED &&
	    (((struct smb2_err_rsp *)shdr)->StructureSize) ==
						SMB2_ERROR_STRUCTURE_SIZE2)
		return NULL;

	/*
	 * 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 (shdr->Command) {
	case SMB2_NEGOTIATE:
		*off = le16_to_cpu(
		  ((struct smb2_negotiate_rsp *)shdr)->SecurityBufferOffset);
		*len = le16_to_cpu(
		  ((struct smb2_negotiate_rsp *)shdr)->SecurityBufferLength);
		break;
	case SMB2_SESSION_SETUP:
		*off = le16_to_cpu(
		  ((struct smb2_sess_setup_rsp *)shdr)->SecurityBufferOffset);
		*len = le16_to_cpu(
		  ((struct smb2_sess_setup_rsp *)shdr)->SecurityBufferLength);
		break;
	case SMB2_CREATE:
		*off = le32_to_cpu(
		    ((struct smb2_create_rsp *)shdr)->CreateContextsOffset);
		*len = le32_to_cpu(
		    ((struct smb2_create_rsp *)shdr)->CreateContextsLength);
		break;
	case SMB2_QUERY_INFO:
		*off = le16_to_cpu(
		    ((struct smb2_query_info_rsp *)shdr)->OutputBufferOffset);
		*len = le32_to_cpu(
		    ((struct smb2_query_info_rsp *)shdr)->OutputBufferLength);
		break;
	case SMB2_READ:
		/* TODO: is this a bug ? */
		*off = ((struct smb2_read_rsp *)shdr)->DataOffset;
		*len = le32_to_cpu(((struct smb2_read_rsp *)shdr)->DataLength);
		break;
	case SMB2_QUERY_DIRECTORY:
		*off = le16_to_cpu(
		  ((struct smb2_query_directory_rsp *)shdr)->OutputBufferOffset);
		*len = le32_to_cpu(
		  ((struct smb2_query_directory_rsp *)shdr)->OutputBufferLength);
		break;
	case SMB2_IOCTL:
		*off = le32_to_cpu(
		  ((struct smb2_ioctl_rsp *)shdr)->OutputOffset);
		*len = le32_to_cpu(
		  ((struct smb2_ioctl_rsp *)shdr)->OutputCount);
		break;
	case SMB2_CHANGE_NOTIFY:
		*off = le16_to_cpu(
		  ((struct smb2_change_notify_rsp *)shdr)->OutputBufferOffset);
		*len = le32_to_cpu(
		  ((struct smb2_change_notify_rsp *)shdr)->OutputBufferLength);
		break;
	default:
		cifs_dbg(VFS, "no length check for command %d\n", le16_to_cpu(shdr->Command));
		break;
	}

	/*
	 * Invalid length or offset probably means data area is invalid, but
	 * we have little choice but to ignore the data area in this case.
	 */
	if (*off > 4096) {
		cifs_dbg(VFS, "offset %d too large, data area ignored\n", *off);
		*len = 0;
		*off = 0;
	} else if (*off < 0) {
		cifs_dbg(VFS, "negative offset %d to data invalid ignore data area\n",
			 *off);
		*off = 0;
		*len = 0;
	} else if (*len < 0) {
		cifs_dbg(VFS, "negative data length %d invalid, data area ignored\n",
			 *len);
		*len = 0;
	} else if (*len > 128 * 1024) {
		cifs_dbg(VFS, "data area larger than 128K: %d\n", *len);
		*len = 0;
	}

	/* return pointer to beginning of data area, ie offset from SMB start */
	if ((*off != 0) && (*len != 0))
		return (char *)shdr + *off;
	else
		return NULL;
}

/*
 * 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.
 */
unsigned int
smb2_calc_size(void *buf, struct TCP_Server_Info *srvr)
{
	struct smb2_sync_pdu *pdu = (struct smb2_sync_pdu *)buf;
	struct smb2_sync_hdr *shdr = &pdu->sync_hdr;
	int offset; /* the offset from the beginning of SMB to data area */
	int data_length; /* the length of the variable length data area */
	/* Structure Size has already been checked to make sure it is 64 */
	int len = le16_to_cpu(shdr->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);

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

	smb2_get_data_area_len(&offset, &data_length, shdr);
	cifs_dbg(FYI, "SMB2 data length %d offset %d\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) {
			cifs_dbg(VFS, "data area offset %d overlaps SMB2 header %d\n",
				 offset + 1, len);
			data_length = 0;
		} else {
			len = offset + data_length;
		}
	}
calc_size_exit:
	cifs_dbg(FYI, "SMB2 len %d\n", len);
	return len;
}

/* Note: caller must free return buffer */
__le16 *
cifs_convert_path_to_utf16(const char *from, struct cifs_sb_info *cifs_sb)
{
	int len;
	const char *start_of_path;
	__le16 *to;
	int map_type;

	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SFM_CHR)
		map_type = SFM_MAP_UNI_RSVD;
	else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR)
		map_type = SFU_MAP_UNI_RSVD;
	else
		map_type = NO_MAP_UNI_RSVD;

	/* Windows doesn't allow paths beginning with \ */
	if (from[0] == '\\')
		start_of_path = from + 1;

	/* SMB311 POSIX extensions paths do not include leading slash */
	else if (cifs_sb_master_tlink(cifs_sb) &&
		 cifs_sb_master_tcon(cifs_sb)->posix_extensions &&
		 (from[0] == '/')) {
		start_of_path = from + 1;
	} else
		start_of_path = from;

	to = cifs_strndup_to_utf16(start_of_path, PATH_MAX, &len,
				   cifs_sb->local_nls, map_type);
	return to;
}

__le32
smb2_get_lease_state(struct cifsInodeInfo *cinode)
{
	__le32 lease = 0;

	if (CIFS_CACHE_WRITE(cinode))
		lease |= SMB2_LEASE_WRITE_CACHING;
	if (CIFS_CACHE_HANDLE(cinode))
		lease |= SMB2_LEASE_HANDLE_CACHING;
	if (CIFS_CACHE_READ(cinode))
		lease |= SMB2_LEASE_READ_CACHING;
	return lease;
}

struct smb2_lease_break_work {
	struct work_struct lease_break;
	struct tcon_link *tlink;
	__u8 lease_key[16];
	__le32 lease_state;
};

static void
cifs_ses_oplock_break(struct work_struct *work)
{
	struct smb2_lease_break_work *lw = container_of(work,
				struct smb2_lease_break_work, lease_break);
	int rc = 0;

	rc = SMB2_lease_break(0, tlink_tcon(lw->tlink), lw->lease_key,
			      lw->lease_state);

	cifs_dbg(FYI, "Lease release rc %d\n", rc);
	cifs_put_tlink(lw->tlink);
	kfree(lw);
}

static bool
smb2_tcon_has_lease(struct cifs_tcon *tcon, struct smb2_lease_break *rsp,
		    struct smb2_lease_break_work *lw)
{
	bool found;
	__u8 lease_state;
	struct list_head *tmp;
	struct cifsFileInfo *cfile;
	struct cifs_pending_open *open;
	struct cifsInodeInfo *cinode;
	int ack_req = le32_to_cpu(rsp->Flags &
				  SMB2_NOTIFY_BREAK_LEASE_FLAG_ACK_REQUIRED);

	lease_state = le32_to_cpu(rsp->NewLeaseState);

	list_for_each(tmp, &tcon->openFileList) {
		cfile = list_entry(tmp, struct cifsFileInfo, tlist);
		cinode = CIFS_I(d_inode(cfile->dentry));

		if (memcmp(cinode->lease_key, rsp->LeaseKey,
							SMB2_LEASE_KEY_SIZE))
			continue;

		cifs_dbg(FYI, "found in the open list\n");
		cifs_dbg(FYI, "lease key match, lease break 0x%x\n",
			 lease_state);

		if (ack_req)
			cfile->oplock_break_cancelled = false;
		else
			cfile->oplock_break_cancelled = true;

		set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);

		cfile->oplock_epoch = le16_to_cpu(rsp->Epoch);
		cfile->oplock_level = lease_state;

		cifs_queue_oplock_break(cfile);
		kfree(lw);
		return true;
	}

	found = false;
	list_for_each_entry(open, &tcon->pending_opens, olist) {
		if (memcmp(open->lease_key, rsp->LeaseKey,
			   SMB2_LEASE_KEY_SIZE))
			continue;

		if (!found && ack_req) {
			found = true;
			memcpy(lw->lease_key, open->lease_key,
			       SMB2_LEASE_KEY_SIZE);
			lw->tlink = cifs_get_tlink(open->tlink);
			queue_work(cifsiod_wq, &lw->lease_break);
		}

		cifs_dbg(FYI, "found in the pending open list\n");
		cifs_dbg(FYI, "lease key match, lease break 0x%x\n",
			 lease_state);

		open->oplock = lease_state;
	}

	return found;
}

static bool
smb2_is_valid_lease_break(char *buffer)
{
	struct smb2_lease_break *rsp = (struct smb2_lease_break *)buffer;
	struct list_head *tmp, *tmp1, *tmp2;
	struct TCP_Server_Info *server;
	struct cifs_ses *ses;
	struct cifs_tcon *tcon;
	struct smb2_lease_break_work *lw;

	lw = kmalloc(sizeof(struct smb2_lease_break_work), GFP_KERNEL);
	if (!lw)
		return false;

	INIT_WORK(&lw->lease_break, cifs_ses_oplock_break);
	lw->lease_state = rsp->NewLeaseState;

	cifs_dbg(FYI, "Checking for lease break\n");

	/* look up tcon based on tid & uid */
	spin_lock(&cifs_tcp_ses_lock);
	list_for_each(tmp, &cifs_tcp_ses_list) {
		server = list_entry(tmp, struct TCP_Server_Info, tcp_ses_list);

		list_for_each(tmp1, &server->smb_ses_list) {
			ses = list_entry(tmp1, struct cifs_ses, smb_ses_list);

			list_for_each(tmp2, &ses->tcon_list) {
				tcon = list_entry(tmp2, struct cifs_tcon,
						  tcon_list);
				spin_lock(&tcon->open_file_lock);
				cifs_stats_inc(
				    &tcon->stats.cifs_stats.num_oplock_brks);
				if (smb2_tcon_has_lease(tcon, rsp, lw)) {
					spin_unlock(&tcon->open_file_lock);
					spin_unlock(&cifs_tcp_ses_lock);
					return true;
				}
				spin_unlock(&tcon->open_file_lock);

				if (tcon->crfid.is_valid &&
				    !memcmp(rsp->LeaseKey,
					    tcon->crfid.fid->lease_key,
					    SMB2_LEASE_KEY_SIZE)) {
					INIT_WORK(&tcon->crfid.lease_break,
						  smb2_cached_lease_break);
					queue_work(cifsiod_wq,
						   &tcon->crfid.lease_break);
					spin_unlock(&cifs_tcp_ses_lock);
					return true;
				}
			}
		}
	}
	spin_unlock(&cifs_tcp_ses_lock);
	kfree(lw);
	cifs_dbg(FYI, "Can not process lease break - no lease matched\n");
	return false;
}

bool
smb2_is_valid_oplock_break(char *buffer, struct TCP_Server_Info *server)
{
	struct smb2_oplock_break *rsp = (struct smb2_oplock_break *)buffer;
	struct list_head *tmp, *tmp1, *tmp2;
	struct cifs_ses *ses;
	struct cifs_tcon *tcon;
	struct cifsInodeInfo *cinode;
	struct cifsFileInfo *cfile;

	cifs_dbg(FYI, "Checking for oplock break\n");

	if (rsp->sync_hdr.Command != SMB2_OPLOCK_BREAK)
		return false;

	if (rsp->StructureSize !=
				smb2_rsp_struct_sizes[SMB2_OPLOCK_BREAK_HE]) {
		if (le16_to_cpu(rsp->StructureSize) == 44)
			return smb2_is_valid_lease_break(buffer);
		else
			return false;
	}

	cifs_dbg(FYI, "oplock level 0x%x\n", rsp->OplockLevel);

	/* look up tcon based on tid & uid */
	spin_lock(&cifs_tcp_ses_lock);
	list_for_each(tmp, &server->smb_ses_list) {
		ses = list_entry(tmp, struct cifs_ses, smb_ses_list);

		list_for_each(tmp1, &ses->tcon_list) {
			tcon = list_entry(tmp1, struct cifs_tcon, tcon_list);

			spin_lock(&tcon->open_file_lock);
			list_for_each(tmp2, &tcon->openFileList) {
				cfile = list_entry(tmp2, struct cifsFileInfo,
						     tlist);
				if (rsp->PersistentFid !=
				    cfile->fid.persistent_fid ||
				    rsp->VolatileFid !=
				    cfile->fid.volatile_fid)
					continue;

				cifs_dbg(FYI, "file id match, oplock break\n");
				cifs_stats_inc(
				    &tcon->stats.cifs_stats.num_oplock_brks);
				cinode = CIFS_I(d_inode(cfile->dentry));
				spin_lock(&cfile->file_info_lock);
				if (!CIFS_CACHE_WRITE(cinode) &&
				    rsp->OplockLevel == SMB2_OPLOCK_LEVEL_NONE)
					cfile->oplock_break_cancelled = true;
				else
					cfile->oplock_break_cancelled = false;

				set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
					&cinode->flags);

				cfile->oplock_epoch = 0;
				cfile->oplock_level = rsp->OplockLevel;

				spin_unlock(&cfile->file_info_lock);

				cifs_queue_oplock_break(cfile);

				spin_unlock(&tcon->open_file_lock);
				spin_unlock(&cifs_tcp_ses_lock);
				return true;
			}
			spin_unlock(&tcon->open_file_lock);
		}
	}
	spin_unlock(&cifs_tcp_ses_lock);
	cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
	return false;
}

void
smb2_cancelled_close_fid(struct work_struct *work)
{
	struct close_cancelled_open *cancelled = container_of(work,
					struct close_cancelled_open, work);
	struct cifs_tcon *tcon = cancelled->tcon;
	int rc;

	if (cancelled->mid)
		cifs_tcon_dbg(VFS, "Close unmatched open for MID:%llx\n",
			      cancelled->mid);
	else
		cifs_tcon_dbg(VFS, "Close interrupted close\n");

	rc = SMB2_close(0, tcon, cancelled->fid.persistent_fid,
			cancelled->fid.volatile_fid);
	if (rc)
		cifs_tcon_dbg(VFS, "Close cancelled mid failed rc:%d\n", rc);

	cifs_put_tcon(tcon);
	kfree(cancelled);
}

/*
 * Caller should already has an extra reference to @tcon
 * This function is used to queue work to close a handle to prevent leaks
 * on the server.
 * We handle two cases. If an open was interrupted after we sent the
 * SMB2_CREATE to the server but before we processed the reply, and second
 * if a close was interrupted before we sent the SMB2_CLOSE to the server.
 */
static int
__smb2_handle_cancelled_cmd(struct cifs_tcon *tcon, __u16 cmd, __u64 mid,
			    __u64 persistent_fid, __u64 volatile_fid)
{
	struct close_cancelled_open *cancelled;

	cancelled = kzalloc(sizeof(*cancelled), GFP_ATOMIC);
	if (!cancelled)
		return -ENOMEM;

	cancelled->fid.persistent_fid = persistent_fid;
	cancelled->fid.volatile_fid = volatile_fid;
	cancelled->tcon = tcon;
	cancelled->cmd = cmd;
	cancelled->mid = mid;
	INIT_WORK(&cancelled->work, smb2_cancelled_close_fid);
	WARN_ON(queue_work(cifsiod_wq, &cancelled->work) == false);

	return 0;
}

int
smb2_handle_cancelled_close(struct cifs_tcon *tcon, __u64 persistent_fid,
			    __u64 volatile_fid)
{
	int rc;

	cifs_dbg(FYI, "%s: tc_count=%d\n", __func__, tcon->tc_count);
	spin_lock(&cifs_tcp_ses_lock);
	if (tcon->tc_count <= 0) {
		struct TCP_Server_Info *server = NULL;

		WARN_ONCE(tcon->tc_count < 0, "tcon refcount is negative");
		spin_unlock(&cifs_tcp_ses_lock);

		if (tcon->ses)
			server = tcon->ses->server;

		cifs_server_dbg(FYI, "tid=%u: tcon is closing, skipping async close retry of fid %llu %llu\n",
				tcon->tid, persistent_fid, volatile_fid);

		return 0;
	}
	tcon->tc_count++;
	spin_unlock(&cifs_tcp_ses_lock);

	rc = __smb2_handle_cancelled_cmd(tcon, SMB2_CLOSE_HE, 0,
					 persistent_fid, volatile_fid);
	if (rc)
		cifs_put_tcon(tcon);

	return rc;
}

int
smb2_handle_cancelled_mid(char *buffer, struct TCP_Server_Info *server)
{
	struct smb2_sync_hdr *sync_hdr = (struct smb2_sync_hdr *)buffer;
	struct smb2_create_rsp *rsp = (struct smb2_create_rsp *)buffer;
	struct cifs_tcon *tcon;
	int rc;

	if (sync_hdr->Command != SMB2_CREATE ||
	    sync_hdr->Status != STATUS_SUCCESS)
		return 0;

	tcon = smb2_find_smb_tcon(server, sync_hdr->SessionId,
				  sync_hdr->TreeId);
	if (!tcon)
		return -ENOENT;

	rc = __smb2_handle_cancelled_cmd(tcon,
					 le16_to_cpu(sync_hdr->Command),
					 le64_to_cpu(sync_hdr->MessageId),
					 rsp->PersistentFileId,
					 rsp->VolatileFileId);
	if (rc)
		cifs_put_tcon(tcon);

	return rc;
}

/**
 * smb311_update_preauth_hash - update @ses hash with the packet data in @iov
 *
 * Assumes @iov does not contain the rfc1002 length and iov[0] has the
 * SMB2 header.
 */
int
smb311_update_preauth_hash(struct cifs_ses *ses, struct kvec *iov, int nvec)
{
	int i, rc;
	struct sdesc *d;
	struct smb2_sync_hdr *hdr;
	struct TCP_Server_Info *server = cifs_ses_server(ses);

	hdr = (struct smb2_sync_hdr *)iov[0].iov_base;
	/* neg prot are always taken */
	if (hdr->Command == SMB2_NEGOTIATE)
		goto ok;

	/*
	 * If we process a command which wasn't a negprot it means the
	 * neg prot was already done, so the server dialect was set
	 * and we can test it. Preauth requires 3.1.1 for now.
	 */
	if (server->dialect != SMB311_PROT_ID)
		return 0;

	if (hdr->Command != SMB2_SESSION_SETUP)
		return 0;

	/* skip last sess setup response */
	if ((hdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
	    && (hdr->Status == NT_STATUS_OK
		|| (hdr->Status !=
		    cpu_to_le32(NT_STATUS_MORE_PROCESSING_REQUIRED))))
		return 0;

ok:
	rc = smb311_crypto_shash_allocate(server);
	if (rc)
		return rc;

	d = server->secmech.sdescsha512;
	rc = crypto_shash_init(&d->shash);
	if (rc) {
		cifs_dbg(VFS, "%s: Could not init sha512 shash\n", __func__);
		return rc;
	}

	rc = crypto_shash_update(&d->shash, ses->preauth_sha_hash,
				 SMB2_PREAUTH_HASH_SIZE);
	if (rc) {
		cifs_dbg(VFS, "%s: Could not update sha512 shash\n", __func__);
		return rc;
	}

	for (i = 0; i < nvec; i++) {
		rc = crypto_shash_update(&d->shash,
					 iov[i].iov_base, iov[i].iov_len);
		if (rc) {
			cifs_dbg(VFS, "%s: Could not update sha512 shash\n",
				 __func__);
			return rc;
		}
	}

	rc = crypto_shash_final(&d->shash, ses->preauth_sha_hash);
	if (rc) {
		cifs_dbg(VFS, "%s: Could not finalize sha512 shash\n",
			 __func__);
		return rc;
	}

	return 0;
}