On Tue, 2023-08-01 at 08:11 +1000, NeilBrown wrote: > 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> > I chose EBADF because the fcntl code uses it for similar purposes. From the manpage: EBADF cmd is F_SETLK or F_SETLKW and the file descriptor open mode doesn't match with the type of lock requested. We're requesting a "lock" here in a delegation, so this made some sense to me. I'm not particular here though. If another error makes more sense, then that's fine. > Reviewed-by: NeilBrown <neilb@xxxxxxx> > Thanks! > 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> > > > > > -- Jeff Layton <jlayton@xxxxxxxxxx>
