From patchwork Fri Jul 15 18:32:57 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 12919572 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 881EACCA482 for ; Fri, 15 Jul 2022 18:33:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230074AbiGOSdF (ORCPT ); Fri, 15 Jul 2022 14:33:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52854 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230113AbiGOSdD (ORCPT ); Fri, 15 Jul 2022 14:33:03 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 47FE07539F for ; Fri, 15 Jul 2022 11:33:02 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D6CD462331 for ; Fri, 15 Jul 2022 18:33:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6D9FC34115; Fri, 15 Jul 2022 18:33:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657909981; bh=j+IVsSwohPRdvc5KVVOn8FGVffOJrfwMlOIlZ+aMelo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H8/ObOO4NNqlZ+iyu6Zxrti/6MTLKs3YB/AW9+f8tqWZmbJci2Nasd9Lsy2baXTbm LPJ5PGVSLUI99CXs1U3kLAGpmaorLY1GppiXcRTaakbkgEqewASvdJHevOG5RulRHp EGhvrIHHBZx9pzZeETFx/2P8L+FpVxokEUzVgjfLzghpE/f1n2VvsXyrPU8Oi9o66+ oI6ITeZkpextWk4O19f/rx8ZwJSolSQuTwN15L8F6UUAdmfjufHav9q6zuBzHUi0ER Dq/xLm7VcEGNI5nqTS+mpq0NxUyCmMlX+R/bZGVkQwLLswrBlfIXecDtd1cxLymUQh /lF4D8r2h41gw== From: Jeff Layton To: chuck.lever@oracle.com Cc: neilb@suse.de, linux-nfs@vger.kernel.org Subject: [PATCH v2 2/2] nfsd: vet the opened dentry after setting a delegation Date: Fri, 15 Jul 2022 14:32:57 -0400 Message-Id: <20220715183257.41129-3-jlayton@kernel.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220715183257.41129-1-jlayton@kernel.org> References: <20220715183257.41129-1-jlayton@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Between opening a file and setting a delegation on it, someone could rename or unlink the dentry. If this happens, we do not want to grant a delegation on the open. On a CLAIM_NULL open, we're opening by filename, and we'll hold the i_rwsem while when attempting to set a delegation. After getting a lease, redo the lookup of the file being opened and validate that the resulting dentry matches the one in the open file description. Signed-off-by: Jeff Layton --- fs/nfsd/nfs4state.c | 52 ++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 47 insertions(+), 5 deletions(-) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index d2d21fdf5c41..a0258214c279 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -5267,11 +5267,42 @@ static int nfsd4_check_conflicting_opens(struct nfs4_client *clp, return 0; } +/* + * It's possible that between opening the dentry and setting the delegation, + * that it has been renamed or unlinked. Redo the lookup to validate that this + * hasn't happened. + */ +static int +nfsd4_vet_deleg_dentry(struct svc_rqst *rqstp, struct nfsd4_open *open, + struct nfs4_file *fp, struct svc_fh *parent) +{ + __be32 err; + struct dentry *child; + struct svc_export *exp; + + lockdep_assert_held(&d_inode(parent->fh_dentry)->i_rwsem); + + err = nfsd_lookup_dentry(rqstp, parent, open->op_fname, open->op_fnamelen, + &exp, &child, true); + if (err) + return -EAGAIN; + + dput(child); + exp_put(exp); + + if (child != file_dentry(fp->fi_deleg_file->nf_file)) + return -EAGAIN; + return 0; +} + static struct nfs4_delegation * -nfs4_set_delegation(struct nfs4_client *clp, - struct nfs4_file *fp, struct nfs4_clnt_odstate *odstate) +nfs4_set_delegation(struct svc_rqst *rqstp, struct nfsd4_open *open, struct nfs4_ol_stateid *stp, + struct svc_fh *parent) { int status = 0; + struct nfs4_client *clp = stp->st_stid.sc_client; + struct nfs4_file *fp = stp->st_stid.sc_file; + struct nfs4_clnt_odstate *odstate = stp->st_clnt_odstate; struct nfs4_delegation *dp; struct nfsd_file *nf; struct file_lock *fl; @@ -5326,6 +5357,13 @@ nfs4_set_delegation(struct nfs4_client *clp, locks_free_lock(fl); if (status) goto out_clnt_odstate; + + if (parent) { + status = nfsd4_vet_deleg_dentry(rqstp, open, fp, parent); + if (status) + goto out_unlock; + } + status = nfsd4_check_conflicting_opens(clp, fp); if (status) goto out_unlock; @@ -5381,11 +5419,13 @@ static void nfsd4_open_deleg_none_ext(struct nfsd4_open *open, int status) * proper support for them. */ static void -nfs4_open_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp) +nfs4_open_delegation(struct svc_rqst *rqstp, struct nfsd4_open *open, struct nfs4_ol_stateid *stp, + struct svc_fh *parent) { struct nfs4_delegation *dp; struct nfs4_openowner *oo = openowner(stp->st_stateowner); struct nfs4_client *clp = stp->st_stid.sc_client; + struct svc_fh *deleg_parent = NULL; int cb_up; int status = 0; @@ -5399,6 +5439,8 @@ nfs4_open_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp) goto out_no_deleg; break; case NFS4_OPEN_CLAIM_NULL: + deleg_parent = parent; + fallthrough; case NFS4_OPEN_CLAIM_FH: /* * Let's not give out any delegations till everyone's @@ -5413,7 +5455,7 @@ nfs4_open_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp) default: goto out_no_deleg; } - dp = nfs4_set_delegation(clp, stp->st_stid.sc_file, stp->st_clnt_odstate); + dp = nfs4_set_delegation(rqstp, open, stp, deleg_parent); if (IS_ERR(dp)) goto out_no_deleg; @@ -5545,7 +5587,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf * Attempt to hand out a delegation. No error return, because the * OPEN succeeds even if we fail. */ - nfs4_open_delegation(open, stp); + nfs4_open_delegation(rqstp, open, stp, &resp->cstate.current_fh); nodeleg: status = nfs_ok; trace_nfsd_open(&stp->st_stid.sc_stateid);