From dc730e173785e29b297aa605786c94adaffe2544 Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Tue, 17 Oct 2006 00:10:13 -0700 Subject: [PATCH] [PATCH] knfsd: nfsd4: fix owner-override on open 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/nfsd/nfs4proc.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c index 8333db12caca..a05d3376cc46 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -68,20 +68,18 @@ fh_dup2(struct svc_fh *dst, struct svc_fh *src) } 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, struct svc_fh *current_fh, struct nfsd4_o &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, struct svc_fh *current_fh, struct nfsd4_ 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; } -- GitLab