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Message-ID: <bd1beb5d5d6862827336aa25a09c2ae16597cc47.camel@kernel.org>
Date: Mon, 26 Aug 2024 10:47:46 -0400
From: Jeff Layton <jlayton@...nel.org>
To: NeilBrown <neilb@...e.de>, Chuck Lever <chuck.lever@...cle.com>
Cc: Olga Kornievskaia <kolga@...app.com>, Dai Ngo <dai.ngo@...cle.com>, Tom
Talpey <tom@...pey.com>, "linux-nfs@...r.kernel.org"
<linux-nfs@...r.kernel.org>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/2] nfsd: CB_GETATTR fixes
On Mon, 2024-08-26 at 10:37 -0400, Jeff Layton wrote:
> On Mon, 2024-08-26 at 09:22 +1000, NeilBrown wrote:
> > On Sun, 25 Aug 2024, Chuck Lever wrote:
> > > On Fri, Aug 23, 2024 at 06:27:37PM -0400, Jeff Layton wrote:
> > > > Fixes for a couple of CB_GETATTR bugs I found while working on the
> > > > delstid set. Mostly this just ensures that we hold references to the
> > > > delegation while working with it.
> > > >
> > > >
> > >
> > > Applied to nfsd-fixes for v6.11-rc, thanks!
> > >
> > > [1/2] nfsd: hold reference to delegation when updating it for cb_getattr
> > > commit: 8fceb5f6636bbbf803fe29fff59f138206559964
> > > [2/2] nfsd: fix potential UAF in nfsd4_cb_getattr_release
> > > commit: 8bc97f9b84c8852fcc56be2382f5115c518de785
> > >
> > > --
> > > Chuck Lever
> > >
> >
> > Maybe the following can tidy up that code. I can split this into
> > a few separate patches if you like.
> > Thoughts?
> >
> > Note that the patch is easier to review if you apply it then use "git
> > diff -b".
> >
> > NeilBrown
> >
> >
> > From: NeilBrown <neilb@...e.de>
> > Subject: [PATCH] nfsd: untangle code in nfsd4_deleg_getattr_conflict()
> >
> > The code in nfsd4_deleg_getattr_conflict() is convoluted and buggy.
> >
> > With this patch we:
> > - properly handle non-nfsd leases. We must not assume flc_owner is a
> > delegation unless fl_lmops == &nfsd_lease_mng_ops
>
> AFAICT, non-nfsd leases are already properly handled (though I do agree
> that the "flow" of this code is awkward). What case do you see that's
> wrong?
>
Doh! Nevermind -- I see it now. It looks like the break_lease tag is
just in the wrong place. We should definitely fix that.
In any case, your patch looks reasonable to me, but I couldn't get it
to apply. Care to send a real PATCH instead? It's fine if you want to
drop my patch and just replace it with yours.
> > - move the main code out of the for loop
> > - have a single exit which calls nfs4_put_stid()
> > (and other exits which don't need to call that)
> >
> > Fixes: c5967721e106 ("NFSD: handle GETATTR conflict with write delegation")
> > Signed-off-by: NeilBrown <neilb@...e.de>
> > ---
> > fs/nfsd/nfs4state.c | 130 ++++++++++++++++++++++----------------------
> > 1 file changed, 65 insertions(+), 65 deletions(-)
> >
> > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > index 2c4b9a22b2bb..7672fa7a70f3 100644
> > --- a/fs/nfsd/nfs4state.c
> > +++ b/fs/nfsd/nfs4state.c
> > @@ -8837,6 +8837,7 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct dentry *dentry,
> > struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
> > struct inode *inode = d_inode(dentry);
> > struct file_lock_context *ctx;
> > + struct nfs4_delegation *dp = NULL;
> > struct nfs4_cb_fattr *ncf;
> > struct file_lease *fl;
> > struct iattr attrs;
> > @@ -8845,77 +8846,76 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct dentry *dentry,
> > ctx = locks_inode_context(inode);
> > if (!ctx)
> > return 0;
> > +
> > +#define NON_NFSD_LEASE ((void*)1)
> > +
> > spin_lock(&ctx->flc_lock);
> > for_each_file_lock(fl, &ctx->flc_lease) {
> > - unsigned char type = fl->c.flc_type;
> > -
> > if (fl->c.flc_flags == FL_LAYOUT)
> > continue;
> > - if (fl->fl_lmops != &nfsd_lease_mng_ops) {
> > - /*
> > - * non-nfs lease, if it's a lease with F_RDLCK then
> > - * we are done; there isn't any write delegation
> > - * on this inode
> > - */
> > - if (type == F_RDLCK)
> > - break;
> > - goto break_lease;
> > - }
> > - if (type == F_WRLCK) {
> > - struct nfs4_delegation *dp = fl->c.flc_owner;
> > -
> > - if (dp->dl_recall.cb_clp == *(rqstp->rq_lease_breaker)) {
> > - spin_unlock(&ctx->flc_lock);
> > - return 0;
> > - }
> > -break_lease:
> > - nfsd_stats_wdeleg_getattr_inc(nn);
> > - dp = fl->c.flc_owner;
> > - refcount_inc(&dp->dl_stid.sc_count);
> > - ncf = &dp->dl_cb_fattr;
> > - nfs4_cb_getattr(&dp->dl_cb_fattr);
> > - spin_unlock(&ctx->flc_lock);
> > - wait_on_bit_timeout(&ncf->ncf_cb_flags, CB_GETATTR_BUSY,
> > - TASK_INTERRUPTIBLE, NFSD_CB_GETATTR_TIMEOUT);
> > - if (ncf->ncf_cb_status) {
> > - /* Recall delegation only if client didn't respond */
> > - status = nfserrno(nfsd_open_break_lease(inode, NFSD_MAY_READ));
> > - if (status != nfserr_jukebox ||
> > - !nfsd_wait_for_delegreturn(rqstp, inode)) {
> > - nfs4_put_stid(&dp->dl_stid);
> > - return status;
> > - }
> > - }
> > - if (!ncf->ncf_file_modified &&
> > - (ncf->ncf_initial_cinfo != ncf->ncf_cb_change ||
> > - ncf->ncf_cur_fsize != ncf->ncf_cb_fsize))
> > - ncf->ncf_file_modified = true;
> > - if (ncf->ncf_file_modified) {
> > - int err;
> > -
> > - /*
> > - * Per section 10.4.3 of RFC 8881, the server would
> > - * not update the file's metadata with the client's
> > - * modified size
> > - */
> > - attrs.ia_mtime = attrs.ia_ctime = current_time(inode);
> > - attrs.ia_valid = ATTR_MTIME | ATTR_CTIME | ATTR_DELEG;
> > - inode_lock(inode);
> > - err = notify_change(&nop_mnt_idmap, dentry, &attrs, NULL);
> > - inode_unlock(inode);
> > - if (err) {
> > - nfs4_put_stid(&dp->dl_stid);
> > - return nfserrno(err);
> > - }
> > - ncf->ncf_cur_fsize = ncf->ncf_cb_fsize;
> > - *size = ncf->ncf_cur_fsize;
> > - *modified = true;
> > - }
> > - nfs4_put_stid(&dp->dl_stid);
> > - return 0;
> > + if (fl->c.flc_type == F_WRLCK) {
> > + if (fl->fl_lmops == &nfsd_lease_mng_ops)
> > + dp = fl->c.flc_owner;
> > + else
> > + dp = NON_NFSD_LEASE;
> > }
> > break;
> > }
> > + if (dp == NULL || dp == NON_NFSD_LEASE ||
> > + dp->dl_recall.cb_clp == *(rqstp->rq_lease_breaker)) {
> > + spin_unlock(&ctx->flc_lock);
> > + if (dp == NON_NFSD_LEASE) {
> > + status = nfserrno(nfsd_open_break_lease(inode,
> > + NFSD_MAY_READ));
> > + if (status != nfserr_jukebox ||
> > + !nfsd_wait_for_delegreturn(rqstp, inode))
> > + return status;
> > + }
> > + return 0;
> > + }
> > +
> > + nfsd_stats_wdeleg_getattr_inc(nn);
> > + refcount_inc(&dp->dl_stid.sc_count);
> > + ncf = &dp->dl_cb_fattr;
> > + nfs4_cb_getattr(&dp->dl_cb_fattr);
> > spin_unlock(&ctx->flc_lock);
> > - return 0;
> > +
> > + wait_on_bit_timeout(&ncf->ncf_cb_flags, CB_GETATTR_BUSY,
> > + TASK_INTERRUPTIBLE, NFSD_CB_GETATTR_TIMEOUT);
> > + if (ncf->ncf_cb_status) {
> > + /* Recall delegation only if client didn't respond */
> > + status = nfserrno(nfsd_open_break_lease(inode, NFSD_MAY_READ));
> > + if (status != nfserr_jukebox ||
> > + !nfsd_wait_for_delegreturn(rqstp, inode))
> > + goto out_status;
> > + }
> > + if (!ncf->ncf_file_modified &&
> > + (ncf->ncf_initial_cinfo != ncf->ncf_cb_change ||
> > + ncf->ncf_cur_fsize != ncf->ncf_cb_fsize))
> > + ncf->ncf_file_modified = true;
> > + if (ncf->ncf_file_modified) {
> > + int err;
> > +
> > + /*
> > + * Per section 10.4.3 of RFC 8881, the server would
> > + * not update the file's metadata with the client's
> > + * modified size
> > + */
> > + attrs.ia_mtime = attrs.ia_ctime = current_time(inode);
> > + attrs.ia_valid = ATTR_MTIME | ATTR_CTIME | ATTR_DELEG;
> > + inode_lock(inode);
> > + err = notify_change(&nop_mnt_idmap, dentry, &attrs, NULL);
> > + inode_unlock(inode);
> > + if (err) {
> > + status = nfserrno(err);
> > + goto out_status;
> > + }
> > + ncf->ncf_cur_fsize = ncf->ncf_cb_fsize;
> > + *size = ncf->ncf_cur_fsize;
> > + *modified = true;
> > + }
> > + status = 0;
> > +out_status:
> > + nfs4_put_stid(&dp->dl_stid);
> > + return status;
> > }
>
> Patch looks like a nice cleanup, but I don't think the Fixes tag is
> appropriate here.
--
Jeff Layton <jlayton@...nel.org>
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