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

7 files changed, 189 insertions, 24 deletions

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index d9ea7ada137..f918a998a08 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -384,6 +384,7 @@ struct smb_version_operations {
 	int (*clone_range)(const unsigned int, struct cifsFileInfo *src_file,
 			struct cifsFileInfo *target_file, u64 src_off, u64 len,
 			u64 dest_off);
+	int (*validate_negotiate)(const unsigned int, struct cifs_tcon *);
 };
 
 struct smb_version_values {
diff --git a/fs/cifs/ioctl.c b/fs/cifs/ioctl.c
index 409b45eefe7..77492301cc2 100644
--- a/fs/cifs/ioctl.c
+++ b/fs/cifs/ioctl.c
@@ -26,13 +26,15 @@
 #include <linux/mount.h>
 #include <linux/mm.h>
 #include <linux/pagemap.h>
-#include <linux/btrfs.h>
 #include "cifspdu.h"
 #include "cifsglob.h"
 #include "cifsproto.h"
 #include "cifs_debug.h"
 #include "cifsfs.h"
 
+#define CIFS_IOCTL_MAGIC	0xCF
+#define CIFS_IOC_COPYCHUNK_FILE	_IOW(CIFS_IOCTL_MAGIC, 3, int)
+
 static long cifs_ioctl_clone(unsigned int xid, struct file *dst_file,
 			unsigned long srcfd, u64 off, u64 len, u64 destoff)
 {
@@ -213,7 +215,7 @@ long cifs_ioctl(struct file *filep, unsigned int command, unsigned long arg)
 				cifs_dbg(FYI, "set compress flag rc %d\n", rc);
 			}
 			break;
-		case BTRFS_IOC_CLONE:
+		case CIFS_IOC_COPYCHUNK_FILE:
 			rc = cifs_ioctl_clone(xid, filep, arg, 0, 0, 0);
 			break;
 		default:
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 11dde4b24f8..757da3e54d3 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 = {
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index d65270c290a..2013234b73a 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -454,6 +454,81 @@ neg_exit:
 	return rc;
 }
 
+int smb3_validate_negotiate(const unsigned int xid, struct cifs_tcon *tcon)
+{
+	int rc = 0;
+	struct validate_negotiate_info_req vneg_inbuf;
+	struct validate_negotiate_info_rsp *pneg_rsp;
+	u32 rsplen;
+
+	cifs_dbg(FYI, "validate negotiate\n");
+
+	/*
+	 * validation ioctl must be signed, so no point sending this if we
+	 * can not sign it.  We could eventually change this to selectively
+	 * sign just this, the first and only signed request on a connection.
+	 * This is good enough for now since a user who wants better security
+	 * would also enable signing on the mount. Having validation of
+	 * negotiate info for signed connections helps reduce attack vectors
+	 */
+	if (tcon->ses->server->sign == false)
+		return 0; /* validation requires signing */
+
+	vneg_inbuf.Capabilities =
+			cpu_to_le32(tcon->ses->server->vals->req_capabilities);
+	memcpy(vneg_inbuf.Guid, cifs_client_guid, SMB2_CLIENT_GUID_SIZE);
+
+	if (tcon->ses->sign)
+		vneg_inbuf.SecurityMode =
+			cpu_to_le16(SMB2_NEGOTIATE_SIGNING_REQUIRED);
+	else if (global_secflags & CIFSSEC_MAY_SIGN)
+		vneg_inbuf.SecurityMode =
+			cpu_to_le16(SMB2_NEGOTIATE_SIGNING_ENABLED);
+	else
+		vneg_inbuf.SecurityMode = 0;
+
+	vneg_inbuf.DialectCount = cpu_to_le16(1);
+	vneg_inbuf.Dialects[0] =
+		cpu_to_le16(tcon->ses->server->vals->protocol_id);
+
+	rc = SMB2_ioctl(xid, tcon, NO_FILE_ID, NO_FILE_ID,
+		FSCTL_VALIDATE_NEGOTIATE_INFO, true /* is_fsctl */,
+		(char *)&vneg_inbuf, sizeof(struct validate_negotiate_info_req),
+		(char **)&pneg_rsp, &rsplen);
+
+	if (rc != 0) {
+		cifs_dbg(VFS, "validate protocol negotiate failed: %d\n", rc);
+		return -EIO;
+	}
+
+	if (rsplen != sizeof(struct validate_negotiate_info_rsp)) {
+		cifs_dbg(VFS, "invalid size of protocol negotiate response\n");
+		return -EIO;
+	}
+
+	/* check validate negotiate info response matches what we got earlier */
+	if (pneg_rsp->Dialect !=
+			cpu_to_le16(tcon->ses->server->vals->protocol_id))
+		goto vneg_out;
+
+	if (pneg_rsp->SecurityMode != cpu_to_le16(tcon->ses->server->sec_mode))
+		goto vneg_out;
+
+	/* do not validate server guid because not saved at negprot time yet */
+
+	if ((le32_to_cpu(pneg_rsp->Capabilities) | SMB2_NT_FIND |
+	      SMB2_LARGE_FILES) != tcon->ses->server->capabilities)
+		goto vneg_out;
+
+	/* validate negotiate successful */
+	cifs_dbg(FYI, "validate negotiate info successful\n");
+	return 0;
+
+vneg_out:
+	cifs_dbg(VFS, "protocol revalidation - security settings mismatch\n");
+	return -EIO;
+}
+
 int
 SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
 		const struct nls_table *nls_cp)
@@ -829,6 +904,8 @@ SMB2_tcon(const unsigned int xid, struct cifs_ses *ses, const char *tree,
 	    ((tcon->share_flags & SHI1005_FLAGS_DFS) == 0))
 		cifs_dbg(VFS, "DFS capability contradicts DFS flag\n");
 	init_copy_chunk_defaults(tcon);
+	if (tcon->ses->server->ops->validate_negotiate)
+		rc = tcon->ses->server->ops->validate_negotiate(xid, tcon);
 tcon_exit:
 	free_rsp_buf(resp_buftype, rsp);
 	kfree(unc_path);
@@ -1214,10 +1291,17 @@ SMB2_ioctl(const unsigned int xid, struct cifs_tcon *tcon, u64 persistent_fid,
 	rc = SendReceive2(xid, ses, iov, num_iovecs, &resp_buftype, 0);
 	rsp = (struct smb2_ioctl_rsp *)iov[0].iov_base;
 
-	if (rc != 0) {
+	if ((rc != 0) && (rc != -EINVAL)) {
 		if (tcon)
 			cifs_stats_fail_inc(tcon, SMB2_IOCTL_HE);
 		goto ioctl_exit;
+	} else if (rc == -EINVAL) {
+		if ((opcode != FSCTL_SRV_COPYCHUNK_WRITE) &&
+		    (opcode != FSCTL_SRV_COPYCHUNK)) {
+			if (tcon)
+				cifs_stats_fail_inc(tcon, SMB2_IOCTL_HE);
+			goto ioctl_exit;
+		}
 	}
 
 	/* check if caller wants to look at return data or just return rc */
@@ -2154,11 +2238,9 @@ send_set_info(const unsigned int xid, struct cifs_tcon *tcon,
 	rc = SendReceive2(xid, ses, iov, num, &resp_buftype, 0);
 	rsp = (struct smb2_set_info_rsp *)iov[0].iov_base;
 
-	if (rc != 0) {
+	if (rc != 0)
 		cifs_stats_fail_inc(tcon, SMB2_SET_INFO_HE);
-		goto out;
-	}
-out:
+
 	free_rsp_buf(resp_buftype, rsp);
 	kfree(iov);
 	return rc;
diff --git a/fs/cifs/smb2pdu.h b/fs/cifs/smb2pdu.h
index f88320bbb47..2022c542ea3 100644
--- a/fs/cifs/smb2pdu.h
+++ b/fs/cifs/smb2pdu.h
@@ -577,13 +577,19 @@ struct copychunk_ioctl_rsp {
 	__le32 TotalBytesWritten;
 } __packed;
 
-/* Response and Request are the same format */
-struct validate_negotiate_info {
+struct validate_negotiate_info_req {
 	__le32 Capabilities;
 	__u8   Guid[SMB2_CLIENT_GUID_SIZE];
 	__le16 SecurityMode;
 	__le16 DialectCount;
-	__le16 Dialect[1];
+	__le16 Dialects[1]; /* dialect (someday maybe list) client asked for */
+} __packed;
+
+struct validate_negotiate_info_rsp {
+	__le32 Capabilities;
+	__u8   Guid[SMB2_CLIENT_GUID_SIZE];
+	__le16 SecurityMode;
+	__le16 Dialect; /* Dialect in use for the connection */
 } __packed;
 
 #define RSS_CAPABLE	0x00000001
diff --git a/fs/cifs/smb2proto.h b/fs/cifs/smb2proto.h
index b4eea105b08..93adc64666f 100644
--- a/fs/cifs/smb2proto.h
+++ b/fs/cifs/smb2proto.h
@@ -162,5 +162,6 @@ extern int smb2_lockv(const unsigned int xid, struct cifs_tcon *tcon,
 		      struct smb2_lock_element *buf);
 extern int SMB2_lease_break(const unsigned int xid, struct cifs_tcon *tcon,
 			    __u8 *lease_key, const __le32 lease_state);
+extern int smb3_validate_negotiate(const unsigned int, struct cifs_tcon *);
 
 #endif			/* _SMB2PROTO_H */
diff --git a/fs/cifs/smbfsctl.h b/fs/cifs/smbfsctl.h
index a4b2391fe66..0e538b5c962 100644
--- a/fs/cifs/smbfsctl.h
+++ b/fs/cifs/smbfsctl.h
@@ -90,7 +90,7 @@
 #define FSCTL_LMR_REQUEST_RESILIENCY 0x001401D4 /* BB add struct */
 #define FSCTL_LMR_GET_LINK_TRACK_INF 0x001400E8 /* BB add struct */
 #define FSCTL_LMR_SET_LINK_TRACK_INF 0x001400EC /* BB add struct */
-#define FSCTL_VALIDATE_NEGOTIATE_INFO 0x00140204 /* BB add struct */
+#define FSCTL_VALIDATE_NEGOTIATE_INFO 0x00140204
 /* Perform server-side data movement */
 #define FSCTL_SRV_COPYCHUNK 0x001440F2
 #define FSCTL_SRV_COPYCHUNK_WRITE 0x001480F2