Commit e255612b authored by Pali Rohár's avatar Pali Rohár Committed by Steve French
Browse files

cifs: Add fallback for SMB2 CREATE without FILE_READ_ATTRIBUTES 



Some operations, like WRITE, does not require FILE_READ_ATTRIBUTES access.

So when FILE_READ_ATTRIBUTES is not explicitly requested for
smb2_open_file() then first try to do SMB2 CREATE with FILE_READ_ATTRIBUTES
access (like it was before) and then fallback to SMB2 CREATE without
FILE_READ_ATTRIBUTES access (less common case).

This change allows to complete WRITE operation to a file when it does not
grant FILE_READ_ATTRIBUTES permission and its parent directory does not
grant READ_DATA permission (parent directory READ_DATA is implicit grant of
child FILE_READ_ATTRIBUTES permission).

Signed-off-by: default avatarPali Rohár <pali@kernel.org>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 4236ac9f

fs/smb/client/smb2file.c

+10 −1
Original line number Diff line number Diff line
@@ -152,16 +152,25 @@ int smb2_open_file(const unsigned int xid, struct cifs_open_parms *oparms, __u32 
	int err_buftype = CIFS_NO_BUFFER;

	struct cifs_fid *fid = oparms->fid;

	struct network_resiliency_req nr_ioctl_req;

	bool retry_without_read_attributes = false;



	smb2_path = cifs_convert_path_to_utf16(oparms->path, oparms->cifs_sb);

	if (smb2_path == NULL)

		return -ENOMEM;



	if (!(oparms->desired_access & FILE_READ_ATTRIBUTES)) {

		oparms->desired_access |= FILE_READ_ATTRIBUTES;

		retry_without_read_attributes = true;

	}

	smb2_oplock = SMB2_OPLOCK_LEVEL_BATCH;



	rc = SMB2_open(xid, oparms, smb2_path, &smb2_oplock, smb2_data, NULL, &err_iov,

		       &err_buftype);

	if (rc == -EACCES && retry_without_read_attributes) {

		oparms->desired_access &= ~FILE_READ_ATTRIBUTES;

		rc = SMB2_open(xid, oparms, smb2_path, &smb2_oplock, smb2_data, NULL, &err_iov,

			       &err_buftype);

	}

	if (rc && data) {

		struct smb2_hdr *hdr = err_iov.iov_base;