All of lore.kernel.org
 help / color / mirror / Atom feed
From: Trond Myklebust <trond.myklebust@primarydata.com>
To: bfields@fieldses.org
Cc: linux-nfs@vger.kernel.org
Subject: [PATCH 1/5] nfsd: Fix stateid races between OPEN and CLOSE
Date: Mon, 30 Oct 2017 20:09:47 -0400	[thread overview]
Message-ID: <20171031000951.18294-2-trond.myklebust@primarydata.com> (raw)
In-Reply-To: <20171031000951.18294-1-trond.myklebust@primarydata.com>

Open file stateids can linger on the nfs4_file list of stateids even
after they have been closed. In order to avoid reusing such a
stateid, and confusing the client, we need to recheck the
nfs4_stid's type after taking the mutex.
Otherwise, we risk reusing an old stateid that was already closed,
which will confuse clients that expect new stateids to conform to
RFC7530 Sections 9.1.4.2 and 16.2.5 or RFC5661 Sections 8.2.2 and 18.2.4.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: stable@vger.kernel.org
---
 fs/nfsd/nfs4state.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 59 insertions(+), 8 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 0c04f81aa63b..b246aaa20863 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -3512,7 +3512,9 @@ nfsd4_find_existing_open(struct nfs4_file *fp, struct nfsd4_open *open)
 		/* ignore lock owners */
 		if (local->st_stateowner->so_is_open_owner == 0)
 			continue;
-		if (local->st_stateowner == &oo->oo_owner) {
+		if (local->st_stateowner != &oo->oo_owner)
+			continue;
+		if (local->st_stid.sc_type == NFS4_OPEN_STID) {
 			ret = local;
 			atomic_inc(&ret->st_stid.sc_count);
 			break;
@@ -3521,6 +3523,52 @@ nfsd4_find_existing_open(struct nfs4_file *fp, struct nfsd4_open *open)
 	return ret;
 }
 
+static __be32
+nfsd4_verify_open_stid(struct nfs4_stid *s)
+{
+	__be32 ret = nfs_ok;
+
+	switch (s->sc_type) {
+	default:
+		break;
+	case NFS4_CLOSED_STID:
+	case NFS4_CLOSED_DELEG_STID:
+		ret = nfserr_bad_stateid;
+		break;
+	case NFS4_REVOKED_DELEG_STID:
+		ret = nfserr_deleg_revoked;
+	}
+	return ret;
+}
+
+/* Lock the stateid st_mutex, and deal with races with CLOSE */
+static __be32
+nfsd4_lock_ol_stateid(struct nfs4_ol_stateid *stp)
+{
+	__be32 ret;
+
+	mutex_lock(&stp->st_mutex);
+	ret = nfsd4_verify_open_stid(&stp->st_stid);
+	if (ret != nfs_ok)
+		mutex_unlock(&stp->st_mutex);
+	return ret;
+}
+
+static struct nfs4_ol_stateid *
+nfsd4_find_and_lock_existing_open(struct nfs4_file *fp, struct nfsd4_open *open)
+{
+	struct nfs4_ol_stateid *stp;
+	for (;;) {
+		spin_lock(&fp->fi_lock);
+		stp = nfsd4_find_existing_open(fp, open);
+		spin_unlock(&fp->fi_lock);
+		if (!stp || nfsd4_lock_ol_stateid(stp) == nfs_ok)
+			break;
+		nfs4_put_stid(&stp->st_stid);
+	}
+	return stp;
+}
+
 static struct nfs4_openowner *
 alloc_init_open_stateowner(unsigned int strhashval, struct nfsd4_open *open,
 			   struct nfsd4_compound_state *cstate)
@@ -3565,6 +3613,7 @@ init_open_stateid(struct nfs4_file *fp, struct nfsd4_open *open)
 	mutex_init(&stp->st_mutex);
 	mutex_lock(&stp->st_mutex);
 
+retry:
 	spin_lock(&oo->oo_owner.so_client->cl_lock);
 	spin_lock(&fp->fi_lock);
 
@@ -3589,7 +3638,11 @@ init_open_stateid(struct nfs4_file *fp, struct nfsd4_open *open)
 	spin_unlock(&fp->fi_lock);
 	spin_unlock(&oo->oo_owner.so_client->cl_lock);
 	if (retstp) {
-		mutex_lock(&retstp->st_mutex);
+		/* Handle races with CLOSE */
+		if (nfsd4_lock_ol_stateid(retstp) != nfs_ok) {
+			nfs4_put_stid(&retstp->st_stid);
+			goto retry;
+		}
 		/* To keep mutex tracking happy */
 		mutex_unlock(&stp->st_mutex);
 		stp = retstp;
@@ -4403,9 +4456,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
 		status = nfs4_check_deleg(cl, open, &dp);
 		if (status)
 			goto out;
-		spin_lock(&fp->fi_lock);
-		stp = nfsd4_find_existing_open(fp, open);
-		spin_unlock(&fp->fi_lock);
+		stp = nfsd4_find_and_lock_existing_open(fp, open);
 	} else {
 		open->op_file = NULL;
 		status = nfserr_bad_stateid;
@@ -4419,7 +4470,6 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
 	 */
 	if (stp) {
 		/* Stateid was found, this is an OPEN upgrade */
-		mutex_lock(&stp->st_mutex);
 		status = nfs4_upgrade_open(rqstp, fp, current_fh, stp, open);
 		if (status) {
 			mutex_unlock(&stp->st_mutex);
@@ -5294,7 +5344,6 @@ static void nfsd4_close_open_stateid(struct nfs4_ol_stateid *s)
 	bool unhashed;
 	LIST_HEAD(reaplist);
 
-	s->st_stid.sc_type = NFS4_CLOSED_STID;
 	spin_lock(&clp->cl_lock);
 	unhashed = unhash_open_stateid(s, &reaplist);
 
@@ -5334,10 +5383,12 @@ nfsd4_close(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	nfsd4_bump_seqid(cstate, status);
 	if (status)
 		goto out; 
+
+	stp->st_stid.sc_type = NFS4_CLOSED_STID;
 	nfs4_inc_and_copy_stateid(&close->cl_stateid, &stp->st_stid);
-	mutex_unlock(&stp->st_mutex);
 
 	nfsd4_close_open_stateid(stp);
+	mutex_unlock(&stp->st_mutex);
 
 	/* put reference from nfs4_preprocess_seqid_op */
 	nfs4_put_stid(&stp->st_stid);
-- 
2.13.6


  reply	other threads:[~2017-10-31  0:09 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-31  0:09 [PATCH 0/5] Tighten up locking around stateids in knfsd Trond Myklebust
2017-10-31  0:09 ` Trond Myklebust [this message]
2017-10-31  0:09   ` [PATCH 2/5] nfsd: CLOSE SHOULD return the invalid special stateid for NFSv4.x (x>0) Trond Myklebust
2017-10-31  0:09     ` [PATCH 3/5] nfsd: Ensure we don't recognise lock stateids after freeing them Trond Myklebust
2017-10-31  0:09       ` [PATCH 4/5] nfsd: Ensure we check stateid validity in the seqid operation checks Trond Myklebust
2017-10-31  0:09         ` [PATCH 5/5] nfsd: Fix races with check_stateid_generation() Trond Myklebust
2017-10-31 17:32     ` [PATCH 2/5] nfsd: CLOSE SHOULD return the invalid special stateid for NFSv4.x (x>0) Frank Filz
2017-10-31 22:33   ` [PATCH 1/5] nfsd: Fix stateid races between OPEN and CLOSE Andrew W Elble
2017-10-31 23:24     ` Trond Myklebust
2017-10-31 23:45       ` Andrew W Elble

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20171031000951.18294-2-trond.myklebust@primarydata.com \
    --to=trond.myklebust@primarydata.com \
    --cc=bfields@fieldses.org \
    --cc=linux-nfs@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.