From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422928AbWJPXaR (ORCPT ); Mon, 16 Oct 2006 19:30:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1422929AbWJPXaR (ORCPT ); Mon, 16 Oct 2006 19:30:17 -0400 Received: from ns2.suse.de ([195.135.220.15]:40135 "EHLO mx2.suse.de") by vger.kernel.org with ESMTP id S1422928AbWJPXaQ (ORCPT ); Mon, 16 Oct 2006 19:30:16 -0400 From: NeilBrown To: Andrew Morton Date: Tue, 17 Oct 2006 09:30:09 +1000 Message-Id: <1061016233009.11318@suse.de> X-face: [Gw_3E*Gng}4rRrKRYotwlE?.2|**#s9D Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: "J. Bruce Fields" If a client creates a file using an open which sets the mode to 000, or if a chmod changes permissions after a file is opened, then situations may arise where an NFS client knows that some IO is permitted (because a process holds the file open), but the NFS server does not (because it doesn't know about the open, and only sees that the IO conflicts with the current mode of the file). As a hack to solve this problem, NFS servers normally allow the owner to override permissions on IO. The client can still enforce correct permissions-checking on open by performing an explicit access check. In NFSv4 the client can rely on the explicit on-the-wire open instead of an access check. Therefore we should not be allowing the owner to override permissions on an over-the-wire open! However, we should still allow the owner to override permissions in the case where the client is claiming an open that it already made either before a reboot, or while it was holding a delegation. Thanks to Jim Rees for reporting the bug. Signed-off-by: J. Bruce Fields Signed-off-by: Neil Brown ### Diffstat output ./fs/nfsd/nfs4proc.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff .prev/fs/nfsd/nfs4proc.c ./fs/nfsd/nfs4proc.c --- .prev/fs/nfsd/nfs4proc.c 2006-10-17 09:02:22.000000000 +1000 +++ ./fs/nfsd/nfs4proc.c 2006-10-17 09:02:26.000000000 +1000 @@ -68,20 +68,18 @@ fh_dup2(struct svc_fh *dst, struct svc_f } static int -do_open_permission(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_open *open) +do_open_permission(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_open *open, int accmode) { - int accmode, status; + int status; if (open->op_truncate && !(open->op_share_access & NFS4_SHARE_ACCESS_WRITE)) return nfserr_inval; - accmode = MAY_NOP; if (open->op_share_access & NFS4_SHARE_ACCESS_READ) - accmode = MAY_READ; + accmode |= MAY_READ; if (open->op_share_deny & NFS4_SHARE_ACCESS_WRITE) accmode |= (MAY_WRITE | MAY_TRUNC); - accmode |= MAY_OWNER_OVERRIDE; status = fh_verify(rqstp, current_fh, S_IFREG, accmode); @@ -124,7 +122,7 @@ do_open_lookup(struct svc_rqst *rqstp, s &resfh.fh_handle.fh_base, resfh.fh_handle.fh_size); - status = do_open_permission(rqstp, current_fh, open); + status = do_open_permission(rqstp, current_fh, open, MAY_NOP); } fh_put(&resfh); @@ -155,7 +153,7 @@ do_open_fhandle(struct svc_rqst *rqstp, open->op_truncate = (open->op_iattr.ia_valid & ATTR_SIZE) && (open->op_iattr.ia_size == 0); - status = do_open_permission(rqstp, current_fh, open); + status = do_open_permission(rqstp, current_fh, open, MAY_OWNER_OVERRIDE); return status; }