cifs: consolidate SendReceive response checks

Further consolidate the SendReceive code by moving the checks run over
the packet into a separate function that all the SendReceive variants
can call.

We can also eliminate the check for a receive_len that's too big or too
small. cifs_demultiplex_thread already checks that and disconnects the
socket if that occurs, while setting the midStatus to MALFORMED. It'll
never call this code if that's the case.

Finally do a little cleanup. Use "goto out" on errors so that the flow
of code in the normal case is more evident. Also switch the logErr
variable in map_smb_to_linux_error to a bool.

Reviewed-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

3 files changed, 45 insertions, 118 deletions

diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 6e69e06a30b3..7aa131112884 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -76,6 +76,8 @@ extern int SendReceive(const unsigned int /* xid */ , struct cifsSesInfo *,
                         int * /* bytes returned */ , const int long_op);
 extern int SendReceiveNoRsp(const unsigned int xid, struct cifsSesInfo *ses,
                         struct smb_hdr *in_buf, int flags);
+extern int cifs_check_receive(struct mid_q_entry *mid,
+                        struct TCP_Server_Info *server, bool log_error);
 extern int SendReceive2(const unsigned int /* xid */ , struct cifsSesInfo *,
                         struct kvec *, int /* nvec to send */,
                         int * /* type of buf returned */ , const int flags);
@@ -99,7 +101,7 @@ extern int cifs_convert_address(struct sockaddr *dst, const char *src, int len);
 extern int cifs_set_port(struct sockaddr *addr, const unsigned short int port);
 extern int cifs_fill_sockaddr(struct sockaddr *dst, const char *src, int len,
                                 const unsigned short int port);
-extern int map_smb_to_linux_error(struct smb_hdr *smb, int logErr);
+extern int map_smb_to_linux_error(struct smb_hdr *smb, bool logErr);
 extern void header_assemble(struct smb_hdr *, char /* command */ ,
                             const struct cifsTconInfo *, int /* length of
                             fixed section (word count) in two byte units */);
diff --git a/fs/cifs/netmisc.c b/fs/cifs/netmisc.c
index 79b71c2c7c9d..73e47e84b61a 100644
--- a/fs/cifs/netmisc.c
+++ b/fs/cifs/netmisc.c
@@ -836,7 +836,7 @@ ntstatus_to_dos(__u32 ntstatus, __u8 *eclass, __u16 *ecode)
 }
 
 int
-map_smb_to_linux_error(struct smb_hdr *smb, int logErr)
+map_smb_to_linux_error(struct smb_hdr *smb, bool logErr)
 {
         unsigned int i;
         int rc = -EIO;  /* if transport error smb error may not be set */
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index f2513fb8c391..43633a79942a 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -502,13 +502,31 @@ send_nt_cancel(struct TCP_Server_Info *server, struct smb_hdr *in_buf,
 }
 
 int
+cifs_check_receive(struct mid_q_entry *mid, struct TCP_Server_Info *server,
+                   bool log_error)
+{
+        dump_smb(mid->resp_buf,
+                 min_t(u32, 92, be32_to_cpu(mid->resp_buf->smb_buf_length)));
+
+        /* convert the length into a more usable form */
+        if (server->secMode & (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED)) {
+                /* FIXME: add code to kill session */
+                if (cifs_verify_signature(mid->resp_buf, server,
+                                          mid->sequence_number + 1) != 0)
+                        cERROR(1, "Unexpected SMB signature");
+        }
+
+        /* BB special case reconnect tid and uid here? */
+        return map_smb_to_linux_error(mid->resp_buf, log_error);
+}
+
+int
 SendReceive2(const unsigned int xid, struct cifsSesInfo *ses,
              struct kvec *iov, int n_vec, int *pRespBufType /* ret */,
              const int flags)
 {
         int rc = 0;
         int long_op;
-        unsigned int receive_len;
         struct mid_q_entry *midQ;
         struct smb_hdr *in_buf = iov[0].iov_base;
 
@@ -605,54 +623,24 @@ SendReceive2(const unsigned int xid, struct cifsSesInfo *ses,
                 return rc;
         }
 
-        receive_len = be32_to_cpu(midQ->resp_buf->smb_buf_length);
-
-        if (receive_len > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE) {
-                cERROR(1, "Frame too large received.  Length: %d  Xid: %d",
-                        receive_len, xid);
+        if (!midQ->resp_buf || midQ->midState != MID_RESPONSE_RECEIVED) {
                 rc = -EIO;
+                cFYI(1, "Bad MID state?");
                 goto out;
         }
 
-        /* rcvd frame is ok */
-
-        if (midQ->resp_buf &&
-            (midQ->midState == MID_RESPONSE_RECEIVED)) {
-
-                iov[0].iov_base = (char *)midQ->resp_buf;
-                if (midQ->largeBuf)
-                        *pRespBufType = CIFS_LARGE_BUFFER;
-                else
-                        *pRespBufType = CIFS_SMALL_BUFFER;
-                iov[0].iov_len = receive_len + 4;
-
-                dump_smb(midQ->resp_buf, 80);
-                /* convert the length into a more usable form */
-                if ((receive_len > 24) &&
-                    (ses->server->secMode & (SECMODE_SIGN_REQUIRED |
-                                             SECMODE_SIGN_ENABLED))) {
-                        rc = cifs_verify_signature(midQ->resp_buf,
-                                                ses->server,
-                                                midQ->sequence_number+1);
-                        if (rc) {
-                                cERROR(1, "Unexpected SMB signature");
-                                /* BB FIXME add code to kill session */
-                        }
-                }
-
-                /* BB special case reconnect tid and uid here? */
-                rc = map_smb_to_linux_error(midQ->resp_buf,
-                                            flags & CIFS_LOG_ERROR);
+        iov[0].iov_base = (char *)midQ->resp_buf;
+        iov[0].iov_len = be32_to_cpu(midQ->resp_buf->smb_buf_length) + 4;
+        if (midQ->largeBuf)
+                *pRespBufType = CIFS_LARGE_BUFFER;
+        else
+                *pRespBufType = CIFS_SMALL_BUFFER;
 
-                if ((flags & CIFS_NO_RESP) == 0)
-                        midQ->resp_buf = NULL;  /* mark it so buf will
-                                                   not be freed by
-                                                   delete_mid */
-        } else {
-                rc = -EIO;
-                cFYI(1, "Bad MID state?");
-        }
+        rc = cifs_check_receive(midQ, ses->server, flags & CIFS_LOG_ERROR);
 
+        /* mark it so buf will not be freed by delete_mid */
+        if ((flags & CIFS_NO_RESP) == 0)
+                midQ->resp_buf = NULL;
 out:
         delete_mid(midQ);
         atomic_dec(&ses->server->inFlight);
@@ -667,7 +655,6 @@ SendReceive(const unsigned int xid, struct cifsSesInfo *ses,
             int *pbytes_returned, const int long_op)
 {
         int rc = 0;
-        unsigned int receive_len;
         struct mid_q_entry *midQ;
 
         if (ses == NULL) {
@@ -757,47 +744,16 @@ SendReceive(const unsigned int xid, struct cifsSesInfo *ses,
                 return rc;
         }
 
-        receive_len = be32_to_cpu(midQ->resp_buf->smb_buf_length);
-
-        if (receive_len > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE) {
-                cERROR(1, "Frame too large received.  Length: %d  Xid: %d",
-                        receive_len, xid);
-                rc = -EIO;
-                goto out;
-        }
-
-        /* rcvd frame is ok */
-
-        if (midQ->resp_buf && out_buf
-            && (midQ->midState == MID_RESPONSE_RECEIVED)) {
-                out_buf->smb_buf_length = cpu_to_be32(receive_len);
-                memcpy((char *)out_buf + 4,
-                       (char *)midQ->resp_buf + 4,
-                       receive_len);
-
-                dump_smb(out_buf, 92);
-                /* convert the length into a more usable form */
-                if ((receive_len > 24) &&
-                    (ses->server->secMode & (SECMODE_SIGN_REQUIRED |
-                                             SECMODE_SIGN_ENABLED))) {
-                        rc = cifs_verify_signature(out_buf,
-                                                ses->server,
-                                                midQ->sequence_number+1);
-                        if (rc) {
-                                cERROR(1, "Unexpected SMB signature");
-                                /* BB FIXME add code to kill session */
-                        }
-                }
-
-                *pbytes_returned = be32_to_cpu(out_buf->smb_buf_length);
-
-                /* BB special case reconnect tid and uid here? */
-                rc = map_smb_to_linux_error(out_buf, 0 /* no log */ );
-        } else {
+        if (!midQ->resp_buf || !out_buf ||
+            midQ->midState != MID_RESPONSE_RECEIVED) {
                 rc = -EIO;
                 cERROR(1, "Bad MID state?");
+                goto out;
         }
 
+        *pbytes_returned = be32_to_cpu(midQ->resp_buf->smb_buf_length);
+        memcpy(out_buf, midQ->resp_buf, *pbytes_returned + 4);
+        rc = cifs_check_receive(midQ, ses->server, 0);
 out:
         delete_mid(midQ);
         atomic_dec(&ses->server->inFlight);
@@ -838,7 +794,6 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifsTconInfo *tcon,
 {
         int rc = 0;
         int rstart = 0;
-        unsigned int receive_len;
         struct mid_q_entry *midQ;
         struct cifsSesInfo *ses;
 
@@ -961,46 +916,16 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifsTconInfo *tcon,
         if (rc != 0)
                 return rc;
 
-        receive_len = be32_to_cpu(midQ->resp_buf->smb_buf_length);
-        if (receive_len > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE) {
-                cERROR(1, "Frame too large received.  Length: %d  Xid: %d",
-                        receive_len, xid);
-                rc = -EIO;
-                goto out;
-        }
-
         /* rcvd frame is ok */
-
-        if ((out_buf == NULL) || (midQ->midState != MID_RESPONSE_RECEIVED)) {
+        if (out_buf == NULL || midQ->midState != MID_RESPONSE_RECEIVED) {
                 rc = -EIO;
                 cERROR(1, "Bad MID state?");
                 goto out;
         }
 
-        out_buf->smb_buf_length = cpu_to_be32(receive_len);
-        memcpy((char *)out_buf + 4,
-               (char *)midQ->resp_buf + 4,
-               receive_len);
-
-        dump_smb(out_buf, 92);
-        /* convert the length into a more usable form */
-        if ((receive_len > 24) &&
-            (ses->server->secMode & (SECMODE_SIGN_REQUIRED |
-                                     SECMODE_SIGN_ENABLED))) {
-                rc = cifs_verify_signature(out_buf,
-                                           ses->server,
-                                           midQ->sequence_number+1);
-                if (rc) {
-                        cERROR(1, "Unexpected SMB signature");
-                        /* BB FIXME add code to kill session */
-                }
-        }
-
-        *pbytes_returned = be32_to_cpu(out_buf->smb_buf_length);
-
-        /* BB special case reconnect tid and uid here? */
-        rc = map_smb_to_linux_error(out_buf, 0 /* no log */ );
-
+        *pbytes_returned = be32_to_cpu(midQ->resp_buf->smb_buf_length);
+        memcpy(out_buf, midQ->resp_buf, *pbytes_returned + 4);
+        rc = cifs_check_receive(midQ, ses->server, 0);
 out:
         delete_mid(midQ);
         if (rstart && rc == -EACCES)