smb: client: fix compound alignment with encryption

The encryption layer can't handle the padding iovs, so flatten the
compound request into a single buffer with required padding to prevent
the server from dropping the connection when finding unaligned
compound requests.

Fixes: bc925c1216f0 ("smb: client: improve compound padding in encryption")
Signed-off-by: Paulo Alcantara (Red Hat) <[e-mail]>
Reviewed-by: David Howells <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Steve French <[e-mail]>

fs/smb/client/smb2ops.c

···
 	}
 
 	/* SMB headers in a compound are 8 byte aligned. */
-	if (!IS_ALIGNED(len, 8)) {
-		num_padding = 8 - (len & 7);
+	if (IS_ALIGNED(len, 8))
+		goto out;
+
+	num_padding = 8 - (len & 7);
+	if (smb3_encryption_required(tcon)) {
+		int i;
+
+		/*
+		 * Flatten request into a single buffer with required padding as
+		 * the encryption layer can't handle the padding iovs.
+		 */
+		for (i = 1; i < rqst->rq_nvec; i++) {
+			memcpy(rqst->rq_iov[0].iov_base +
+			       rqst->rq_iov[0].iov_len,
+			       rqst->rq_iov[i].iov_base,
+			       rqst->rq_iov[i].iov_len);
+			rqst->rq_iov[0].iov_len += rqst->rq_iov[i].iov_len;
+		}
+		memset(rqst->rq_iov[0].iov_base + rqst->rq_iov[0].iov_len,
+		       0, num_padding);
+		rqst->rq_iov[0].iov_len += num_padding;
+		rqst->rq_nvec = 1;
+	} else {
 		rqst->rq_iov[rqst->rq_nvec].iov_base = smb2_padding;
 		rqst->rq_iov[rqst->rq_nvec].iov_len = num_padding;
 		rqst->rq_nvec++;
-		len += num_padding;
 	}
+	len += num_padding;
+out:
 	shdr->NextCommand = cpu_to_le32(len);
 }