CIFS: Separate SMB2 header structure

BugLink: http://bugs.launchpad.net/bugs/1670508

In order to support compounding and encryption we need to separate
RFC1001 length field and SMB2 header structure because the protocol
treats them differently. This change will allow to simplify parsing
of such complex SMB2 packets further.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
(cherry picked from commit 31473fc4)
Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>

fs/cifs/smb2glob.h

@@ -61,4 +61,9 @@
 /* Maximum buffer size value we can send with 1 credit */
 #define SMB2_MAX_BUFFER_SIZE 65536
 
+static inline struct smb2_sync_hdr *get_sync_hdr(void *buf)
+{
+	return &(((struct smb2_hdr *)buf)->sync_hdr);
+}
+
 #endif	/* _SMB2_GLOB_H */

fs/cifs/smb2maperror.c

@@ -26,6 +26,7 @@
 #include "smb2pdu.h"
 #include "smb2proto.h"
 #include "smb2status.h"
+#include "smb2glob.h"
 
 struct status_to_posix_error {
 	__le32 smb2_status;
@@ -2449,10 +2450,10 @@ smb2_print_status(__le32 status)
 int
 map_smb2_to_linux_error(char *buf, bool log_err)
 {
-	struct smb2_hdr *hdr = (struct smb2_hdr *)buf;
+	struct smb2_sync_hdr *shdr = get_sync_hdr(buf);
 	unsigned int i;
 	int rc = -EIO;
-	__le32 smb2err = hdr->Status;
+	__le32 smb2err = shdr->Status;
 
 	if (smb2err == 0)
 		return 0;

fs/cifs/smb2misc.c

@@ -28,31 +28,32 @@
 #include "cifs_debug.h"
 #include "cifs_unicode.h"
 #include "smb2status.h"
+#include "smb2glob.h"
 
 static int
-check_smb2_hdr(struct smb2_hdr *hdr, __u64 mid)
+check_smb2_hdr(struct smb2_sync_hdr *shdr, __u64 mid)
 {
-	__u64 wire_mid = le64_to_cpu(hdr->MessageId);
+	__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 ((hdr->ProtocolId == SMB2_PROTO_NUMBER) &&
+	if ((shdr->ProtocolId == SMB2_PROTO_NUMBER) &&
 	    (mid == wire_mid)) {
-		if (hdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
+		if (shdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
 			return 0;
 		else {
 			/* only one valid case where server sends us request */
-			if (hdr->Command == SMB2_OPLOCK_BREAK)
+			if (shdr->Command == SMB2_OPLOCK_BREAK)
 				return 0;
 			else
 				cifs_dbg(VFS, "Received Request not response\n");
 		}
 	} else { /* bad signature or mid */
-		if (hdr->ProtocolId != SMB2_PROTO_NUMBER)
+		if (shdr->ProtocolId != SMB2_PROTO_NUMBER)
 			cifs_dbg(VFS, "Bad protocol string signature header %x\n",
-				 le32_to_cpu(hdr->ProtocolId));
+				 le32_to_cpu(shdr->ProtocolId));
 		if (mid != wire_mid)
 			cifs_dbg(VFS, "Mids do not match: %llu and %llu\n",
 				 mid, wire_mid);
@@ -95,8 +96,9 @@ static const __le16 smb2_rsp_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = {
 int
 smb2_check_message(char *buf, unsigned int length, struct TCP_Server_Info *srvr)
 {
-	struct smb2_hdr *hdr = (struct smb2_hdr *)buf;
-	struct smb2_pdu *pdu = (struct smb2_pdu *)hdr;
+	struct smb2_pdu *pdu = (struct smb2_pdu *)buf;
+	struct smb2_hdr *hdr = &pdu->hdr;
+	struct smb2_sync_hdr *shdr = get_sync_hdr(buf);
 	__u64 mid;
 	__u32 len = get_rfc1002_length(buf);
 	__u32 clc_len;  /* calculated length */
@@ -111,7 +113,7 @@ smb2_check_message(char *buf, unsigned int length, struct TCP_Server_Info *srvr)
 	 * ie Validate the wct via smb2_struct_sizes table above
 	 */
 
-	if (hdr->ProtocolId == SMB2_TRANSFORM_PROTO_NUM) {
+	if (shdr->ProtocolId == SMB2_TRANSFORM_PROTO_NUM) {
 		struct smb2_transform_hdr *thdr =
 			(struct smb2_transform_hdr *)buf;
 		struct cifs_ses *ses = NULL;
@@ -133,10 +135,10 @@ smb2_check_message(char *buf, unsigned int length, struct TCP_Server_Info *srvr)
 		}
 	}
 
-
-	mid = le64_to_cpu(hdr->MessageId);
+	mid = le64_to_cpu(shdr->MessageId);
 	if (length < sizeof(struct smb2_pdu)) {
-		if ((length >= sizeof(struct smb2_hdr)) && (hdr->Status != 0)) {
+		if ((length >= sizeof(struct smb2_hdr))
+		    && (shdr->Status != 0)) {
 			pdu->StructureSize2 = 0;
 			/*
 			 * As with SMB/CIFS, on some error cases servers may
@@ -154,29 +156,30 @@ smb2_check_message(char *buf, unsigned int length, struct TCP_Server_Info *srvr)
 		return 1;
 	}
 
-	if (check_smb2_hdr(hdr, mid))
+	if (check_smb2_hdr(shdr, mid))
 		return 1;
 
-	if (hdr->StructureSize != SMB2_HEADER_STRUCTURE_SIZE) {
+	if (shdr->StructureSize != SMB2_HEADER_STRUCTURE_SIZE) {
 		cifs_dbg(VFS, "Illegal structure size %u\n",
-			 le16_to_cpu(hdr->StructureSize));
+			 le16_to_cpu(shdr->StructureSize));
 		return 1;
 	}
 
-	command = le16_to_cpu(hdr->Command);
+	command = le16_to_cpu(shdr->Command);
 	if (command >= NUMBER_OF_SMB2_COMMANDS) {
 		cifs_dbg(VFS, "Illegal SMB2 command %d\n", command);
 		return 1;
 	}
 
 	if (smb2_rsp_struct_sizes[command] != pdu->StructureSize2) {
-		if (command != SMB2_OPLOCK_BREAK_HE && (hdr->Status == 0 ||
+		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, "Illegal response size %u for command %d\n",
 				 le16_to_cpu(pdu->StructureSize2), command);
 			return 1;
-		} else if (command == SMB2_OPLOCK_BREAK_HE && (hdr->Status == 0)
+		} 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 */
@@ -199,7 +202,7 @@ smb2_check_message(char *buf, unsigned int length, struct TCP_Server_Info *srvr)
 			 clc_len, 4 + len, mid);
 		/* create failed on symlink */
 		if (command == SMB2_CREATE_HE &&
-		    hdr->Status == STATUS_STOPPED_ON_SYMLINK)
+		    shdr->Status == STATUS_STOPPED_ON_SYMLINK)
 			return 0;
 		/* Windows 7 server returns 24 bytes more */
 		if (clc_len + 20 == len && command == SMB2_OPLOCK_BREAK_HE)
@@ -261,11 +264,12 @@ static const bool has_smb2_data_area[NUMBER_OF_SMB2_COMMANDS] = {
 char *
 smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *hdr)
 {
+	struct smb2_sync_hdr *shdr = get_sync_hdr(hdr);
 	*off = 0;
 	*len = 0;
 
 	/* error responses do not have data area */
-	if (hdr->Status && hdr->Status != STATUS_MORE_PROCESSING_REQUIRED &&
+	if (shdr->Status && shdr->Status != STATUS_MORE_PROCESSING_REQUIRED &&
 	    (((struct smb2_err_rsp *)hdr)->StructureSize) ==
 						SMB2_ERROR_STRUCTURE_SIZE2)
 		return NULL;
@@ -275,7 +279,7 @@ smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *hdr)
 	 * of the data buffer offset and data buffer length for the particular
 	 * command.
 	 */
-	switch (hdr->Command) {
+	switch (shdr->Command) {
 	case SMB2_NEGOTIATE:
 		*off = le16_to_cpu(
 		    ((struct smb2_negotiate_rsp *)hdr)->SecurityBufferOffset);
@@ -346,7 +350,7 @@ smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *hdr)
 
 	/* return pointer to beginning of data area, ie offset from SMB start */
 	if ((*off != 0) && (*len != 0))
-		return (char *)(&hdr->ProtocolId) + *off;
+		return (char *)shdr + *off;
 	else
 		return NULL;
 }
@@ -358,12 +362,13 @@ smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *hdr)
 unsigned int
 smb2_calc_size(void *buf)
 {
-	struct smb2_hdr *hdr = (struct smb2_hdr *)buf;
-	struct smb2_pdu *pdu = (struct smb2_pdu *)hdr;
+	struct smb2_pdu *pdu = (struct smb2_pdu *)buf;
+	struct smb2_hdr *hdr = &pdu->hdr;
+	struct smb2_sync_hdr *shdr = get_sync_hdr(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 = 4 + le16_to_cpu(pdu->hdr.StructureSize);
+	int len = 4 + le16_to_cpu(shdr->StructureSize);
 
 	/*
 	 * StructureSize2, ie length of fixed parameter area has already
@@ -371,7 +376,7 @@ smb2_calc_size(void *buf)
 	 */
 	len += le16_to_cpu(pdu->StructureSize2);
 
-	if (has_smb2_data_area[le16_to_cpu(hdr->Command)] == false)
+	if (has_smb2_data_area[le16_to_cpu(shdr->Command)] == false)
 		goto calc_size_exit;
 
 	smb2_get_data_area_len(&offset, &data_length, hdr);
@@ -582,7 +587,7 @@ smb2_is_valid_oplock_break(char *buffer, struct TCP_Server_Info *server)
 
 	cifs_dbg(FYI, "Checking for oplock break\n");
 
-	if (rsp->hdr.Command != SMB2_OPLOCK_BREAK)
+	if (rsp->hdr.sync_hdr.Command != SMB2_OPLOCK_BREAK)
 		return false;
 
 	if (rsp->StructureSize !=

fs/cifs/smb2ops.c

@@ -118,7 +118,9 @@ smb2_get_credits_field(struct TCP_Server_Info *server, const int optype)
 static unsigned int
 smb2_get_credits(struct mid_q_entry *mid)
 {
-	return le16_to_cpu(((struct smb2_hdr *)mid->resp_buf)->CreditRequest);
+	struct smb2_sync_hdr *shdr = get_sync_hdr(mid->resp_buf);
+
+	return le16_to_cpu(shdr->CreditRequest);
 }
 
 static int
@@ -183,10 +185,10 @@ static struct mid_q_entry *
 smb2_find_mid(struct TCP_Server_Info *server, char *buf)
 {
 	struct mid_q_entry *mid;
-	struct smb2_hdr *hdr = (struct smb2_hdr *)buf;
-	__u64 wire_mid = le64_to_cpu(hdr->MessageId);
+	struct smb2_sync_hdr *shdr = get_sync_hdr(buf);
+	__u64 wire_mid = le64_to_cpu(shdr->MessageId);
 
-	if (hdr->ProtocolId == SMB2_TRANSFORM_PROTO_NUM) {
+	if (shdr->ProtocolId == SMB2_TRANSFORM_PROTO_NUM) {
 		cifs_dbg(VFS, "encrypted frame parsing not supported yet");
 		return NULL;
 	}
@@ -195,7 +197,7 @@ smb2_find_mid(struct TCP_Server_Info *server, char *buf)
 	list_for_each_entry(mid, &server->pending_mid_q, qhead) {
 		if ((mid->mid == wire_mid) &&
 		    (mid->mid_state == MID_REQUEST_SUBMITTED) &&
-		    (mid->command == hdr->Command)) {
+		    (mid->command == shdr->Command)) {
 			spin_unlock(&GlobalMid_Lock);
 			return mid;
 		}
@@ -208,12 +210,12 @@ static void
 smb2_dump_detail(void *buf)
 {
 #ifdef CONFIG_CIFS_DEBUG2
-	struct smb2_hdr *smb = (struct smb2_hdr *)buf;
+	struct smb2_sync_hdr *shdr = get_sync_hdr(buf);
 
 	cifs_dbg(VFS, "Cmd: %d Err: 0x%x Flags: 0x%x Mid: %llu Pid: %d\n",
-		 smb->Command, smb->Status, smb->Flags, smb->MessageId,
-		 smb->ProcessId);
-	cifs_dbg(VFS, "smb buf %p len %u\n", smb, smb2_calc_size(smb));
+		 shdr->Command, shdr->Status, shdr->Flags, shdr->MessageId,
+		 shdr->ProcessId);
+	cifs_dbg(VFS, "smb buf %p len %u\n", buf, smb2_calc_size(buf));
 #endif
 }
 
@@ -957,14 +959,14 @@ smb2_close_dir(const unsigned int xid, struct cifs_tcon *tcon,
 static bool
 smb2_is_status_pending(char *buf, struct TCP_Server_Info *server, int length)
 {
-	struct smb2_hdr *hdr = (struct smb2_hdr *)buf;
+	struct smb2_sync_hdr *shdr = get_sync_hdr(buf);
 
-	if (hdr->Status != STATUS_PENDING)
+	if (shdr->Status != STATUS_PENDING)
 		return false;
 
 	if (!length) {
 		spin_lock(&server->req_lock);
-		server->credits += le16_to_cpu(hdr->CreditRequest);
+		server->credits += le16_to_cpu(shdr->CreditRequest);
 		spin_unlock(&server->req_lock);
 		wake_up(&server->request_q);
 	}

fs/cifs/smb2pdu.h

@@ -99,10 +99,7 @@
 
 #define SMB2_HEADER_STRUCTURE_SIZE cpu_to_le16(64)
 
-struct smb2_hdr {
-	__be32 smb2_buf_length;	/* big endian on wire */
-				/* length is only two or three bytes - with
-				 one or two byte type preceding it that MBZ */
+struct smb2_sync_hdr {
 	__le32 ProtocolId;	/* 0xFE 'S' 'M' 'B' */
 	__le16 StructureSize;	/* 64 */
 	__le16 CreditCharge;	/* MBZ */
@@ -118,6 +115,13 @@ struct smb2_hdr {
 	__u8   Signature[16];
 } __packed;
 
+struct smb2_hdr {
+	__be32 smb2_buf_length;	/* big endian on wire */
+				/* length is only two or three bytes - with */
+				/* one or two byte type preceding it that MBZ */
+	struct smb2_sync_hdr sync_hdr;
+} __packed;
+
 struct smb2_pdu {
 	struct smb2_hdr hdr;
 	__le16 StructureSize2; /* size of wct area (varies, request specific) */

fs/cifs/smb2transport.c

@@ -115,13 +115,13 @@ smb3_crypto_shash_allocate(struct TCP_Server_Info *server)
 }
 
 static struct cifs_ses *
-smb2_find_smb_ses(struct smb2_hdr *smb2hdr, struct TCP_Server_Info *server)
+smb2_find_smb_ses(struct smb2_sync_hdr *shdr, struct TCP_Server_Info *server)
 {
 	struct cifs_ses *ses;
 
 	spin_lock(&cifs_tcp_ses_lock);
 	list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
-		if (ses->Suid != smb2hdr->SessionId)
+		if (ses->Suid != shdr->SessionId)
 			continue;
 		spin_unlock(&cifs_tcp_ses_lock);
 		return ses;
@@ -131,7 +131,6 @@ smb2_find_smb_ses(struct smb2_hdr *smb2hdr, struct TCP_Server_Info *server)
 	return NULL;
 }
 
-
 int
 smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 {
@@ -139,17 +138,17 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 	unsigned char smb2_signature[SMB2_HMACSHA256_SIZE];
 	unsigned char *sigptr = smb2_signature;
 	struct kvec *iov = rqst->rq_iov;
-	struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)iov[0].iov_base;
+	struct smb2_sync_hdr *shdr = get_sync_hdr(iov[0].iov_base);
 	struct cifs_ses *ses;
 
-	ses = smb2_find_smb_ses(smb2_pdu, server);
+	ses = smb2_find_smb_ses(shdr, server);
 	if (!ses) {
 		cifs_dbg(VFS, "%s: Could not find session\n", __func__);
 		return 0;
 	}
 
 	memset(smb2_signature, 0x0, SMB2_HMACSHA256_SIZE);
-	memset(smb2_pdu->Signature, 0x0, SMB2_SIGNATURE_SIZE);
+	memset(shdr->Signature, 0x0, SMB2_SIGNATURE_SIZE);
 
 	rc = smb2_crypto_shash_allocate(server);
 	if (rc) {
@@ -174,7 +173,7 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 		&server->secmech.sdeschmacsha256->shash);
 
 	if (!rc)
-		memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
+		memcpy(shdr->Signature, sigptr, SMB2_SIGNATURE_SIZE);
 
 	return rc;
 }
@@ -356,17 +355,17 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 	unsigned char smb3_signature[SMB2_CMACAES_SIZE];
 	unsigned char *sigptr = smb3_signature;
 	struct kvec *iov = rqst->rq_iov;
-	struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)iov[0].iov_base;
+	struct smb2_sync_hdr *shdr = get_sync_hdr(iov[0].iov_base);
 	struct cifs_ses *ses;
 
-	ses = smb2_find_smb_ses(smb2_pdu, server);
+	ses = smb2_find_smb_ses(shdr, server);
 	if (!ses) {
 		cifs_dbg(VFS, "%s: Could not find session\n", __func__);
 		return 0;
 	}
 
 	memset(smb3_signature, 0x0, SMB2_CMACAES_SIZE);
-	memset(smb2_pdu->Signature, 0x0, SMB2_SIGNATURE_SIZE);
+	memset(shdr->Signature, 0x0, SMB2_SIGNATURE_SIZE);
 
 	rc = crypto_shash_setkey(server->secmech.cmacaes,
 		ses->smb3signingkey, SMB2_CMACAES_SIZE);
@@ -391,7 +390,7 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 				   &server->secmech.sdesccmacaes->shash);
 
 	if (!rc)
-		memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
+		memcpy(shdr->Signature, sigptr, SMB2_SIGNATURE_SIZE);
 
 	return rc;
 }
@@ -401,14 +400,14 @@ static int
 smb2_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 {
 	int rc = 0;
-	struct smb2_hdr *smb2_pdu = rqst->rq_iov[0].iov_base;
+	struct smb2_sync_hdr *shdr = get_sync_hdr(rqst->rq_iov[0].iov_base);
 
-	if (!(smb2_pdu->Flags & SMB2_FLAGS_SIGNED) ||
+	if (!(shdr->Flags & SMB2_FLAGS_SIGNED) ||
 	    server->tcpStatus == CifsNeedNegotiate)
 		return rc;
 
 	if (!server->session_estab) {
-		strncpy(smb2_pdu->Signature, "BSRSPYL", 8);
+		strncpy(shdr->Signature, "BSRSPYL", 8);
 		return rc;
 	}
 
@@ -422,11 +421,11 @@ smb2_verify_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 {
 	unsigned int rc;
 	char server_response_sig[16];
-	struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)rqst->rq_iov[0].iov_base;
+	struct smb2_sync_hdr *shdr = get_sync_hdr(rqst->rq_iov[0].iov_base);
 
-	if ((smb2_pdu->Command == SMB2_NEGOTIATE) ||
-	    (smb2_pdu->Command == SMB2_SESSION_SETUP) ||
-	    (smb2_pdu->Command == SMB2_OPLOCK_BREAK) ||
+	if ((shdr->Command == SMB2_NEGOTIATE) ||
+	    (shdr->Command == SMB2_SESSION_SETUP) ||
+	    (shdr->Command == SMB2_OPLOCK_BREAK) ||
 	    (!server->session_estab))
 		return 0;
 
@@ -436,17 +435,17 @@ smb2_verify_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 	 */
 
 	/* Do not need to verify session setups with signature "BSRSPYL " */
-	if (memcmp(smb2_pdu->Signature, "BSRSPYL ", 8) == 0)
+	if (memcmp(shdr->Signature, "BSRSPYL ", 8) == 0)
 		cifs_dbg(FYI, "dummy signature received for smb command 0x%x\n",
-			 smb2_pdu->Command);
+			 shdr->Command);
 
 	/*
 	 * Save off the origiginal signature so we can modify the smb and check
 	 * our calculated signature against what the server sent.
 	 */
-	memcpy(server_response_sig, smb2_pdu->Signature, SMB2_SIGNATURE_SIZE);
+	memcpy(server_response_sig, shdr->Signature, SMB2_SIGNATURE_SIZE);
 
-	memset(smb2_pdu->Signature, 0, SMB2_SIGNATURE_SIZE);
+	memset(shdr->Signature, 0, SMB2_SIGNATURE_SIZE);
 
 	mutex_lock(&server->srv_mutex);
 	rc = server->ops->calc_signature(rqst, server);
@@ -455,8 +454,7 @@ smb2_verify_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 	if (rc)
 		return rc;
 
-	if (memcmp(server_response_sig, smb2_pdu->Signature,
-		   SMB2_SIGNATURE_SIZE))
+	if (memcmp(server_response_sig, shdr->Signature, SMB2_SIGNATURE_SIZE))
 		return -EACCES;
 	else
 		return 0;
@@ -467,18 +465,19 @@ smb2_verify_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
  * and when srv_mutex is held.
  */
 static inline void
-smb2_seq_num_into_buf(struct TCP_Server_Info *server, struct smb2_hdr *hdr)
+smb2_seq_num_into_buf(struct TCP_Server_Info *server,
+		      struct smb2_sync_hdr *shdr)
 {
-	unsigned int i, num = le16_to_cpu(hdr->CreditCharge);
+	unsigned int i, num = le16_to_cpu(shdr->CreditCharge);
 
-	hdr->MessageId = get_next_mid64(server);
+	shdr->MessageId = get_next_mid64(server);
 	/* skip message numbers according to CreditCharge field */
 	for (i = 1; i < num; i++)
 		get_next_mid(server);
 }
 
 static struct mid_q_entry *
-smb2_mid_entry_alloc(const struct smb2_hdr *smb_buffer,
+smb2_mid_entry_alloc(const struct smb2_sync_hdr *shdr,
 		     struct TCP_Server_Info *server)
 {
 	struct mid_q_entry *temp;
@@ -493,9 +492,9 @@ smb2_mid_entry_alloc(const struct smb2_hdr *smb_buffer,
 		return temp;
 	else {
 		memset(temp, 0, sizeof(struct mid_q_entry));
-		temp->mid = le64_to_cpu(smb_buffer->MessageId);
+		temp->mid = le64_to_cpu(shdr->MessageId);
 		temp->pid = current->pid;
-		temp->command = smb_buffer->Command;	/* Always LE */
+		temp->command = shdr->Command; /* Always LE */
 		temp->when_alloc = jiffies;
 		temp->server = server;
 
@@ -513,7 +512,7 @@ smb2_mid_entry_alloc(const struct smb2_hdr *smb_buffer,
 }
 
 static int
-smb2_get_mid_entry(struct cifs_ses *ses, struct smb2_hdr *buf,
+smb2_get_mid_entry(struct cifs_ses *ses, struct smb2_sync_hdr *shdr,
 		   struct mid_q_entry **mid)
 {
 	if (ses->server->tcpStatus == CifsExiting)
@@ -525,19 +524,19 @@ smb2_get_mid_entry(struct cifs_ses *ses, struct smb2_hdr *buf,
 	}
 
 	if (ses->status == CifsNew) {
-		if ((buf->Command != SMB2_SESSION_SETUP) &&
-		    (buf->Command != SMB2_NEGOTIATE))
+		if ((shdr->Command != SMB2_SESSION_SETUP) &&
+		    (shdr->Command != SMB2_NEGOTIATE))
 			return -EAGAIN;
 		/* else ok - we are setting up session */
 	}
 
 	if (ses->status == CifsExiting) {
-		if (buf->Command != SMB2_LOGOFF)
+		if (shdr->Command != SMB2_LOGOFF)
 			return -EAGAIN;
 		/* else ok - we are shutting down the session */
 	}
 
-	*mid = smb2_mid_entry_alloc(buf, ses->server);
+	*mid = smb2_mid_entry_alloc(shdr, ses->server);
 	if (*mid == NULL)
 		return -ENOMEM;
 	spin_lock(&GlobalMid_Lock);
@@ -576,12 +575,12 @@ struct mid_q_entry *
 smb2_setup_request(struct cifs_ses *ses, struct smb_rqst *rqst)
 {
 	int rc;
-	struct smb2_hdr *hdr = (struct smb2_hdr *)rqst->rq_iov[0].iov_base;
+	struct smb2_sync_hdr *shdr = get_sync_hdr(rqst->rq_iov[0].iov_base);
 	struct mid_q_entry *mid;
 
-	smb2_seq_num_into_buf(ses->server, hdr);
+	smb2_seq_num_into_buf(ses->server, shdr);
 
-	rc = smb2_get_mid_entry(ses, hdr, &mid);
+	rc = smb2_get_mid_entry(ses, shdr, &mid);
 	if (rc)
 		return ERR_PTR(rc);
 	rc = smb2_sign_rqst(rqst, ses->server);
@@ -596,12 +595,12 @@ struct mid_q_entry *
 smb2_setup_async_request(struct TCP_Server_Info *server, struct smb_rqst *rqst)
 {
 	int rc;
-	struct smb2_hdr *hdr = (struct smb2_hdr *)rqst->rq_iov[0].iov_base;
+	struct smb2_sync_hdr *shdr = get_sync_hdr(rqst->rq_iov[0].iov_base);
 	struct mid_q_entry *mid;
 
-	smb2_seq_num_into_buf(server, hdr);
+	smb2_seq_num_into_buf(server, shdr);
 
-	mid = smb2_mid_entry_alloc(hdr, server);
+	mid = smb2_mid_entry_alloc(shdr, server);
 	if (mid == NULL)
 		return ERR_PTR(-ENOMEM);