On Tue, 01 Aug 2023, Jeff Layton wrote: > I noticed that xfstests generic/001 was failing against linux-next nfsd. > > The client would request a OPEN4_SHARE_ACCESS_WRITE open, and the server > would hand out a write delegation. The client would then try to use that > write delegation as the source stateid in a COPY or CLONE operation, and > the server would respond with NFS4ERR_STALE. > > The problem is that the struct file associated with the delegation does > not necessarily have read permissions. It's handing out a write > delegation on what is effectively an O_WRONLY open. RFC 8881 states: > > "An OPEN_DELEGATE_WRITE delegation allows the client to handle, on its > own, all opens." > > Given that the client didn't request any read permissions, and that nfsd > didn't check for any, it seems wrong to give out a write delegation. > > Don't hand out a delegation if the client didn't request > OPEN4_SHARE_ACCESS_BOTH. > > This fixes xfstest generic/001. > > Closes: https://bugzilla.linux-nfs.org/show_bug.cgi?id=412 > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> > --- > fs/nfsd/nfs4state.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > index ef7118ebee00..9f1c90afed72 100644 > --- a/fs/nfsd/nfs4state.c > +++ b/fs/nfsd/nfs4state.c > @@ -5462,6 +5462,8 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp, > return ERR_PTR(-EAGAIN); > > if (open->op_share_access & NFS4_SHARE_ACCESS_WRITE) { > + if (!(open->op_share_access & NFS4_SHARE_ACCESS_READ)) > + return ERR_PTR(-EBADF); <bikeshed> The actual error code returned by nfs4_set_delegation() is ignored - only the fact of an error is relevant. Given that, how did you choose -EBADF. nfsd doesn't use file descriptors, and doesn't use EBADF anywhere else. Given that you have just tested access, EACCES might be justifiable. But I would prefer if nfs4_set_delegation() returns NULL if it could not find or create a delegation, without bothering with giving a reason. </bikeshed> Reviewed-by: NeilBrown <neilb@xxxxxxx> NeilBrown > nf = find_writeable_file(fp); > dl_type = NFS4_OPEN_DELEGATE_WRITE; > } else { > > --- > base-commit: ec89391563792edd11d138a853901bce76d11f44 > change-id: 20230731-wdeleg-bbdb6b25a3c6 > > Best regards, > -- > Jeff Layton <jlayton@xxxxxxxxxx> > >
