Merge branch 'for-next' of git://git.samba.org/sfrench/cifs-2.6

Pull cifs fixes from Steve French:
 "SMB3 "validate negotiate" is needed to prevent certain types of
  downgrade attacks.

  Also changes SMB2/SMB3 copy offload from using the BTRFS copy ioctl
  (BTRFS_IOC_CLONE) to a cifs specific ioctl (CIFS_IOC_COPYCHUNK_FILE)
  to address Christoph's comment that there are semantic differences
  between requesting copy offload in which copy-on-write is mandatory
  (as in the BTRFS ioctl) and optional in the SMB2/SMB3 case.  Also
  fixes SMB2/SMB3 copychunk for large files"

* 'for-next' of git://git.samba.org/sfrench/cifs-2.6:
  [CIFS] Do not use btrfs refcopy ioctl for SMB2 copy offload
  Check SMB3 dialects against downgrade attacks
  Removed duplicated (and unneeded) goto
  CIFS: Fix SMB2/SMB3 Copy offload support (refcopy) for large files

1 files changed, 86 insertions, 13 deletions

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 11dde4b24f8a..757da3e54d3d 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -532,7 +532,10 @@ smb2_clone_range(const unsigned int xid,
 	int rc;
 	unsigned int ret_data_len;
 	struct copychunk_ioctl *pcchunk;
-	char *retbuf = NULL;
+	struct copychunk_ioctl_rsp *retbuf = NULL;
+	struct cifs_tcon *tcon;
+	int chunks_copied = 0;
+	bool chunk_sizes_updated = false;
 
 	pcchunk = kmalloc(sizeof(struct copychunk_ioctl), GFP_KERNEL);
 
@@ -547,27 +550,96 @@ smb2_clone_range(const unsigned int xid,
 
 	/* Note: request_res_key sets res_key null only if rc !=0 */
 	if (rc)
-		return rc;
+		goto cchunk_out;
 
 	/* For now array only one chunk long, will make more flexible later */
 	pcchunk->ChunkCount = __constant_cpu_to_le32(1);
 	pcchunk->Reserved = 0;
-	pcchunk->SourceOffset = cpu_to_le64(src_off);
-	pcchunk->TargetOffset = cpu_to_le64(dest_off);
-	pcchunk->Length = cpu_to_le32(len);
 	pcchunk->Reserved2 = 0;
 
-	/* Request that server copy to target from src file identified by key */
-	rc = SMB2_ioctl(xid, tlink_tcon(trgtfile->tlink),
-			trgtfile->fid.persistent_fid,
-			trgtfile->fid.volatile_fid, FSCTL_SRV_COPYCHUNK_WRITE,
-			true /* is_fsctl */, (char *)pcchunk,
-			sizeof(struct copychunk_ioctl),	&retbuf, &ret_data_len);
+	tcon = tlink_tcon(trgtfile->tlink);
 
-	/* BB need to special case rc = EINVAL to alter chunk size */
+	while (len > 0) {
+		pcchunk->SourceOffset = cpu_to_le64(src_off);
+		pcchunk->TargetOffset = cpu_to_le64(dest_off);
+		pcchunk->Length =
+			cpu_to_le32(min_t(u32, len, tcon->max_bytes_chunk));
 
-	cifs_dbg(FYI, "rc %d data length out %d\n", rc, ret_data_len);
+		/* Request server copy to target from src identified by key */
+		rc = SMB2_ioctl(xid, tcon, trgtfile->fid.persistent_fid,
+			trgtfile->fid.volatile_fid, FSCTL_SRV_COPYCHUNK_WRITE,
+			true /* is_fsctl */, (char *)pcchunk,
+			sizeof(struct copychunk_ioctl),	(char **)&retbuf,
+			&ret_data_len);
+		if (rc == 0) {
+			if (ret_data_len !=
+					sizeof(struct copychunk_ioctl_rsp)) {
+				cifs_dbg(VFS, "invalid cchunk response size\n");
+				rc = -EIO;
+				goto cchunk_out;
+			}
+			if (retbuf->TotalBytesWritten == 0) {
+				cifs_dbg(FYI, "no bytes copied\n");
+				rc = -EIO;
+				goto cchunk_out;
+			}
+			/*
+			 * Check if server claimed to write more than we asked
+			 */
+			if (le32_to_cpu(retbuf->TotalBytesWritten) >
+			    le32_to_cpu(pcchunk->Length)) {
+				cifs_dbg(VFS, "invalid copy chunk response\n");
+				rc = -EIO;
+				goto cchunk_out;
+			}
+			if (le32_to_cpu(retbuf->ChunksWritten) != 1) {
+				cifs_dbg(VFS, "invalid num chunks written\n");
+				rc = -EIO;
+				goto cchunk_out;
+			}
+			chunks_copied++;
+
+			src_off += le32_to_cpu(retbuf->TotalBytesWritten);
+			dest_off += le32_to_cpu(retbuf->TotalBytesWritten);
+			len -= le32_to_cpu(retbuf->TotalBytesWritten);
+
+			cifs_dbg(FYI, "Chunks %d PartialChunk %d Total %d\n",
+				le32_to_cpu(retbuf->ChunksWritten),
+				le32_to_cpu(retbuf->ChunkBytesWritten),
+				le32_to_cpu(retbuf->TotalBytesWritten));
+		} else if (rc == -EINVAL) {
+			if (ret_data_len != sizeof(struct copychunk_ioctl_rsp))
+				goto cchunk_out;
+
+			cifs_dbg(FYI, "MaxChunks %d BytesChunk %d MaxCopy %d\n",
+				le32_to_cpu(retbuf->ChunksWritten),
+				le32_to_cpu(retbuf->ChunkBytesWritten),
+				le32_to_cpu(retbuf->TotalBytesWritten));
+
+			/*
+			 * Check if this is the first request using these sizes,
+			 * (ie check if copy succeed once with original sizes
+			 * and check if the server gave us different sizes after
+			 * we already updated max sizes on previous request).
+			 * if not then why is the server returning an error now
+			 */
+			if ((chunks_copied != 0) || chunk_sizes_updated)
+				goto cchunk_out;
+
+			/* Check that server is not asking us to grow size */
+			if (le32_to_cpu(retbuf->ChunkBytesWritten) <
+					tcon->max_bytes_chunk)
+				tcon->max_bytes_chunk =
+					le32_to_cpu(retbuf->ChunkBytesWritten);
+			else
+				goto cchunk_out; /* server gave us bogus size */
+
+			/* No need to change MaxChunks since already set to 1 */
+			chunk_sizes_updated = true;
+		}
+	}
 
+cchunk_out:
 	kfree(pcchunk);
 	return rc;
 }
@@ -1247,6 +1319,7 @@ struct smb_version_operations smb30_operations = {
 	.create_lease_buf = smb3_create_lease_buf,
 	.parse_lease_buf = smb3_parse_lease_buf,
 	.clone_range = smb2_clone_range,
+	.validate_negotiate = smb3_validate_negotiate,
 };
 
 struct smb_version_values smb20_values = {