nfsd: Fix stateid races between OPEN and CLOSE
commit 15ca08d3299682dc49bad73251677b2c5017ef08 upstream.
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>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index ec2a69d..8fae634 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -3513,7 +3513,9 @@
/* 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;
@@ -3522,6 +3524,52 @@
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)
@@ -3566,6 +3614,7 @@
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);
@@ -3590,7 +3639,11 @@
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;
@@ -4411,9 +4464,7 @@
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;
@@ -4427,7 +4478,6 @@
*/
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);
@@ -5314,7 +5364,6 @@
bool unhashed;
LIST_HEAD(reaplist);
- s->st_stid.sc_type = NFS4_CLOSED_STID;
spin_lock(&clp->cl_lock);
unhashed = unhash_open_stateid(s, &reaplist);
@@ -5353,10 +5402,12 @@
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);