From: NeilBrown <neilb@suse.de>
Date: Tue, 7 Dec 2021 10:45:19 +1100
Subject: [PATCH] nfsd: prepare for supporting admin-revocation of state
Patch-mainline: Submitted, Jan 2022 nfs-utils@vger.kernel.org
References: bsc#1192483

The NFSv4 protocol allows state to be revoked by the admin and has error
codes which allow this to be communicated to the client.

This patch
 - introduces 3 new state-id types for revoked open, lock, and
   delegation state.  This requires the bitmask to be 'short',
   not 'char'
 - reports NFS4ERR_ADMIN_REVOKED when these are accessed
 - introduces a per-client counter of these states and returns
   SEQ4_STATUS_ADMIN_STATE_REVOKED when the counter is not zero
 - introduces stub code to find all interesting states for a given
   superblock so they can be revoked via the 'unlock_filesystem'
   file in /proc/fs/nfsd/
   No actual states are handled yet.

Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: NeilBrown <neilb@suse.com>

---
 fs/nfsd/nfs4layouts.c |    2 -
 fs/nfsd/nfs4state.c   |   88 ++++++++++++++++++++++++++++++++++++++++++++++----
 fs/nfsd/nfsctl.c      |    1 
 fs/nfsd/nfsd.h        |    1 
 fs/nfsd/state.h       |   25 +++++++++-----
 5 files changed, 100 insertions(+), 17 deletions(-)

--- a/fs/nfsd/nfs4layouts.c
+++ b/fs/nfsd/nfs4layouts.c
@@ -268,7 +268,7 @@ nfsd4_preprocess_layout_stateid(struct s
 {
 	struct nfs4_layout_stateid *ls;
 	struct nfs4_stid *stid;
-	unsigned char typemask = NFS4_LAYOUT_STID;
+	unsigned short typemask = NFS4_LAYOUT_STID;
 	__be32 status;
 
 	if (create)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1483,6 +1483,54 @@ static void release_openowner(struct nfs
 	nfs4_put_stateowner(&oo->oo_owner);
 }
 
+static struct nfs4_stid *find_sb_stid(struct nfs4_client *clp,
+				      struct super_block *sb,
+				      unsigned short sc_types)
+{
+	unsigned long id = 0;
+	struct nfs4_stid *stid;
+
+	spin_lock(&clp->cl_lock);
+	do {
+		id += 1;
+		stid = idr_get_next_ul(&clp->cl_stateids, &id);
+	} while (stid &&
+		 !((stid->sc_type & sc_types) &&
+		   stid->sc_file->fi_sb == sb));
+	if (stid)
+		refcount_inc(&stid->sc_count);
+	spin_unlock(&clp->cl_lock);
+	return stid;
+}
+
+void nfsd4_revoke_states(struct net *net, struct super_block *sb)
+{
+	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
+	unsigned int idhashval;
+	unsigned short sc_types;
+
+	sc_types = 0;
+
+	spin_lock(&nn->client_lock);
+	for (idhashval = 0; idhashval < CLIENT_HASH_MASK; idhashval++) {
+		struct list_head *head = &nn->conf_id_hashtbl[idhashval];
+		struct nfs4_client *clp;
+	retry:
+		list_for_each_entry(clp, head, cl_idhash) {
+			struct nfs4_stid *stid = find_sb_stid(clp, sb, sc_types);
+			if (stid) {
+				spin_unlock(&nn->client_lock);
+				switch (stid->sc_type) {
+				}
+				nfs4_put_stid(stid);
+				spin_lock(&nn->client_lock);
+				goto retry;
+			}
+		}
+	}
+	spin_unlock(&nn->client_lock);
+}
+
 static inline int
 hash_sessionid(struct nfs4_sessionid *sessionid)
 {
@@ -2238,7 +2286,8 @@ find_stateid_locked(struct nfs4_client *
 }
 
 static struct nfs4_stid *
-find_stateid_by_type(struct nfs4_client *cl, stateid_t *t, char typemask)
+find_stateid_by_type(struct nfs4_client *cl, stateid_t *t,
+		     unsigned short typemask)
 {
 	struct nfs4_stid *s;
 
@@ -2294,6 +2343,8 @@ static int client_info_show(struct seq_f
 		seq_printf(m, "\nImplementation time: [%ld, %ld]\n",
 			clp->cl_nii_time.tv_sec, clp->cl_nii_time.tv_nsec);
 	}
+	seq_printf(m, "admin-revoked states: %d\n",
+		   atomic_read(&clp->cl_admin_revoked));
 	drop_client(clp);
 
 	return 0;
@@ -3692,6 +3743,8 @@ out:
 	}
 	if (!list_empty(&clp->cl_revoked))
 		seq->status_flags |= SEQ4_STATUS_RECALLABLE_STATE_REVOKED;
+	if (atomic_read(&clp->cl_admin_revoked))
+		seq->status_flags |= SEQ4_STATUS_ADMIN_STATE_REVOKED;
 out_no_session:
 	if (conn)
 		free_conn(conn);
@@ -3943,7 +3996,7 @@ static struct nfs4_file *nfsd4_alloc_fil
 
 /* OPEN Share state helper functions */
 static void nfsd4_init_file(struct knfsd_fh *fh, unsigned int hashval,
-				struct nfs4_file *fp)
+			    struct nfs4_file *fp, struct super_block *sb)
 {
 	lockdep_assert_held(&state_lock);
 
@@ -3958,6 +4011,7 @@ static void nfsd4_init_file(struct knfsd
 	fp->fi_share_deny = 0;
 	memset(fp->fi_fds, 0, sizeof(fp->fi_fds));
 	memset(fp->fi_access, 0, sizeof(fp->fi_access));
+	fp->fi_sb = sb;
 #ifdef CONFIG_NFSD_PNFS
 	INIT_LIST_HEAD(&fp->fi_lo_states);
 	atomic_set(&fp->fi_lo_recalls, 0);
@@ -4140,6 +4194,11 @@ nfsd4_verify_open_stid(struct nfs4_stid
 		break;
 	case NFS4_REVOKED_DELEG_STID:
 		ret = nfserr_deleg_revoked;
+		break;
+	case NFS4_ADMIN_REVOKED_STID:
+	case NFS4_ADMIN_REVOKED_DELEG_STID:
+		ret = nfserr_admin_revoked;
+		break;
 	}
 	return ret;
 }
@@ -4323,7 +4382,7 @@ find_file(struct knfsd_fh *fh)
 }
 
 static struct nfs4_file *
-find_or_add_file(struct nfs4_file *new, struct knfsd_fh *fh)
+find_or_add_file(struct nfs4_file *new, struct knfsd_fh *fh, struct super_block *sb)
 {
 	struct nfs4_file *fp;
 	unsigned int hashval = file_hashval(fh);
@@ -4337,7 +4396,7 @@ find_or_add_file(struct nfs4_file *new,
 	spin_lock(&state_lock);
 	fp = find_file_locked(fh, hashval);
 	if (likely(fp == NULL)) {
-		nfsd4_init_file(fh, hashval, new);
+		nfsd4_init_file(fh, hashval, new, sb);
 		fp = new;
 	}
 	spin_unlock(&state_lock);
@@ -4639,6 +4698,11 @@ nfs4_check_deleg(struct nfs4_client *cl,
 			status = nfserr_deleg_revoked;
 		goto out;
 	}
+	if (deleg->dl_stid.sc_type == NFS4_ADMIN_REVOKED_DELEG_STID) {
+		nfs4_put_stid(&deleg->dl_stid);
+		status = nfserr_admin_revoked;
+		goto out;
+	}
 	flags = share_access_to_flags(open->op_share_access);
 	status = nfs4_check_delegmode(deleg, flags);
 	if (status) {
@@ -5016,7 +5080,8 @@ nfsd4_process_open2(struct svc_rqst *rqs
 	 * and check for delegations in the process of being recalled.
 	 * If not found, create the nfs4_file struct
 	 */
-	fp = find_or_add_file(open->op_file, &current_fh->fh_handle);
+	fp = find_or_add_file(open->op_file, &current_fh->fh_handle,
+			      current_fh->fh_dentry->d_sb);
 	if (fp != open->op_file) {
 		status = nfs4_check_deleg(cl, open, &dp);
 		if (status)
@@ -5491,6 +5556,11 @@ static __be32 nfsd4_validate_stateid(str
 	case NFS4_REVOKED_DELEG_STID:
 		status = nfserr_deleg_revoked;
 		break;
+	case NFS4_ADMIN_REVOKED_STID:
+	case NFS4_ADMIN_REVOKED_LOCK_STID:
+	case NFS4_ADMIN_REVOKED_DELEG_STID:
+		status = nfserr_admin_revoked;
+		break;
 	case NFS4_OPEN_STID:
 	case NFS4_LOCK_STID:
 		status = nfsd4_check_openowner_confirmed(openlockstateid(s));
@@ -5509,7 +5579,7 @@ out_unlock:
 
 __be32
 nfsd4_lookup_stateid(struct nfsd4_compound_state *cstate,
-		     stateid_t *stateid, unsigned char typemask,
+		     stateid_t *stateid, unsigned short typemask,
 		     struct nfs4_stid **s, struct nfsd_net *nn)
 {
 	__be32 status;
@@ -5544,6 +5614,10 @@ nfsd4_lookup_stateid(struct nfsd4_compou
 			return nfserr_deleg_revoked;
 		return nfserr_bad_stateid;
 	}
+	if (((*s)->sc_type == NFS4_ADMIN_REVOKED_DELEG_STID) && !return_revoked) {
+		nfs4_put_stid(*s);
+		return nfserr_admin_revoked;
+	}
 	return nfs_ok;
 }
 
@@ -5801,7 +5875,7 @@ static __be32 nfs4_seqid_op_checks(struc
  */
 static __be32
 nfs4_preprocess_seqid_op(struct nfsd4_compound_state *cstate, u32 seqid,
-			 stateid_t *stateid, char typemask,
+			 stateid_t *stateid, unsigned short typemask,
 			 struct nfs4_ol_stateid **stpp,
 			 struct nfsd_net *nn)
 {
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -322,6 +322,7 @@ static ssize_t write_unlock_fs(struct fi
 	 * 3.  Is that directory the root of an exported file system?
 	 */
 	error = nlmsvc_unlock_all_by_sb(path.dentry->d_sb);
+	nfsd4_revoke_states(netns(file), path.dentry->d_sb);
 
 	path_put(&path);
 	return error;
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -235,6 +235,7 @@ void		nfsd_lockd_shutdown(void);
 #define	nfserr_no_grace		cpu_to_be32(NFSERR_NO_GRACE)
 #define	nfserr_reclaim_bad	cpu_to_be32(NFSERR_RECLAIM_BAD)
 #define	nfserr_badname		cpu_to_be32(NFSERR_BADNAME)
+#define	nfserr_admin_revoked	cpu_to_be32(NFS4ERR_ADMIN_REVOKED)
 #define	nfserr_cb_path_down	cpu_to_be32(NFSERR_CB_PATH_DOWN)
 #define	nfserr_locked		cpu_to_be32(NFSERR_LOCKED)
 #define	nfserr_wrongsec		cpu_to_be32(NFSERR_WRONGSEC)
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -87,16 +87,19 @@ struct nfsd4_callback_ops {
  */
 struct nfs4_stid {
 	refcount_t		sc_count;
-#define NFS4_OPEN_STID 1
-#define NFS4_LOCK_STID 2
-#define NFS4_DELEG_STID 4
+	unsigned short		sc_type;
+#define NFS4_OPEN_STID			BIT(0)
+#define NFS4_LOCK_STID			BIT(1)
+#define NFS4_DELEG_STID			BIT(2)
 /* For an open stateid kept around *only* to process close replays: */
-#define NFS4_CLOSED_STID 8
+#define NFS4_CLOSED_STID		BIT(3)
 /* For a deleg stateid kept around only to process free_stateid's: */
-#define NFS4_REVOKED_DELEG_STID 16
-#define NFS4_CLOSED_DELEG_STID 32
-#define NFS4_LAYOUT_STID 64
-	unsigned char		sc_type;
+#define NFS4_REVOKED_DELEG_STID		BIT(4)
+#define NFS4_CLOSED_DELEG_STID		BIT(5)
+#define NFS4_LAYOUT_STID		BIT(6)
+#define NFS4_ADMIN_REVOKED_STID		BIT(7)
+#define NFS4_ADMIN_REVOKED_LOCK_STID	BIT(8)
+#define NFS4_ADMIN_REVOKED_DELEG_STID	BIT(9)
 	stateid_t		sc_stateid;
 	spinlock_t		sc_lock;
 	struct nfs4_client	*sc_client;
@@ -317,6 +320,7 @@ struct nfs4_client {
 	clientid_t		cl_clientid;	/* generated by server */
 	nfs4_verifier		cl_confirm;	/* generated by server */
 	u32			cl_minorversion;
+	atomic_t		cl_admin_revoked; /* count of admin-revoked states */
 	/* NFSv4.1 client implementation id: */
 	struct xdr_netobj	cl_nii_domain;
 	struct xdr_netobj	cl_nii_name;
@@ -497,6 +501,7 @@ struct nfs4_clnt_odstate {
  */
 struct nfs4_file {
 	refcount_t		fi_ref;
+	struct super_block *	fi_sb;
 	spinlock_t		fi_lock;
 	struct hlist_node       fi_hash;	/* hash on fi_fhandle */
 	struct list_head        fi_stateids;
@@ -618,7 +623,7 @@ extern __be32 nfs4_preprocess_stateid_op
 		struct nfsd4_compound_state *cstate, struct svc_fh *fhp,
 		stateid_t *stateid, int flags, struct file **filp, bool *tmp_file);
 __be32 nfsd4_lookup_stateid(struct nfsd4_compound_state *cstate,
-		     stateid_t *stateid, unsigned char typemask,
+		     stateid_t *stateid, unsigned short typemask,
 		     struct nfs4_stid **s, struct nfsd_net *nn);
 struct nfs4_stid *nfs4_alloc_stid(struct nfs4_client *cl, struct kmem_cache *slab,
 				  void (*sc_free)(struct nfs4_stid *));
@@ -659,6 +664,8 @@ static inline void get_nfs4_file(struct
 }
 struct file *find_any_file(struct nfs4_file *f);
 
+void nfsd4_revoke_states(struct net *net, struct super_block *sb);
+
 /* grace period management */
 void nfsd4_end_grace(struct nfsd_net *nn);