ksmbd: add support for durable handles v1/v2

Durable file handles allow reopening a file preserved on a short
network outage and transparent client reconnection within a timeout.
i.e. Durable handles aren't necessarily cleaned up when the opening
process terminates.

This patch add support for durable handle version 1 and 2.

To prove durable handles work on ksmbd, I have tested this patch with
the following smbtorture tests:

smb2.durable-open.open-oplock
smb2.durable-open.open-lease
smb2.durable-open.reopen1
smb2.durable-open.reopen1a
smb2.durable-open.reopen1a-lease
smb2.durable-open.reopen2
smb2.durable-open.reopen2a
smb2.durable-open.reopen2-lease
smb2.durable-open.reopen2-lease-v2
smb2.durable-open.reopen3
smb2.durable-open.reopen4
smb2.durable-open.delete_on_close2
smb2.durable-open.file-position
smb2.durable-open.lease
smb2.durable-open.alloc-size
smb2.durable-open.read-only
smb2.durable-v2-open.create-blob
smb2.durable-v2-open.open-oplock
smb2.durable-v2-open.open-lease
smb2.durable-v2-open.reopen1
smb2.durable-v2-open.reopen1a
smb2.durable-v2-open.reopen1a-lease
smb2.durable-v2-open.reopen2
smb2.durable-v2-open.reopen2b

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/server/ksmbd_netlink.h

@@ -75,6 +75,7 @@ struct ksmbd_heartbeat {
 #define KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION	BIT(1)
 #define KSMBD_GLOBAL_FLAG_SMB3_MULTICHANNEL	BIT(2)
 #define KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION_OFF	BIT(3)
+#define KSMBD_GLOBAL_FLAG_DURABLE_HANDLE	BIT(4)
 
 /*
  * IPC request for ksmbd server startup

fs/smb/server/mgmt/user_session.c

@@ -324,6 +324,7 @@ void destroy_previous_session(struct ksmbd_conn *conn,
 	    memcmp(user->passkey, prev_user->passkey, user->passkey_sz))
 		goto out;
 
+	ksmbd_destroy_file_table(&prev_sess->file_table);
 	prev_sess->state = SMB2_SESSION_EXPIRED;
 out:
 	up_write(&conn->session_lock);

fs/smb/server/oplock.c

@@ -159,7 +159,8 @@ static struct oplock_info *opinfo_get_list(struct ksmbd_inode *ci)
 	opinfo = list_first_or_null_rcu(&ci->m_op_list, struct oplock_info,
 					op_entry);
 	if (opinfo) {
-		if (!atomic_inc_not_zero(&opinfo->refcount))
+		if (opinfo->conn == NULL ||
+		    !atomic_inc_not_zero(&opinfo->refcount))
 			opinfo = NULL;
 		else {
 			atomic_inc(&opinfo->conn->r_count);
@@ -527,7 +528,7 @@ static struct oplock_info *same_client_has_lease(struct ksmbd_inode *ci,
 	 */
 	read_lock(&ci->m_lock);
 	list_for_each_entry(opinfo, &ci->m_op_list, op_entry) {
-		if (!opinfo->is_lease)
+		if (!opinfo->is_lease || !opinfo->conn)
 			continue;
 		read_unlock(&ci->m_lock);
 		lease = opinfo->o_lease;
@@ -641,7 +642,7 @@ static void __smb2_oplock_break_noti(struct work_struct *wk)
 	struct smb2_hdr *rsp_hdr;
 	struct ksmbd_file *fp;
 
-	fp = ksmbd_lookup_durable_fd(br_info->fid);
+	fp = ksmbd_lookup_global_fd(br_info->fid);
 	if (!fp)
 		goto out;
 
@@ -1106,7 +1107,7 @@ void smb_send_parent_lease_break_noti(struct ksmbd_file *fp,
 
 	read_lock(&p_ci->m_lock);
 	list_for_each_entry(opinfo, &p_ci->m_op_list, op_entry) {
-		if (!opinfo->is_lease)
+		if (opinfo->conn == NULL || !opinfo->is_lease)
 			continue;
 
 		if (opinfo->o_lease->state != SMB2_OPLOCK_LEVEL_NONE &&
@@ -1151,7 +1152,7 @@ void smb_lazy_parent_lease_break_close(struct ksmbd_file *fp)
 
 	read_lock(&p_ci->m_lock);
 	list_for_each_entry(opinfo, &p_ci->m_op_list, op_entry) {
-		if (!opinfo->is_lease)
+		if (opinfo->conn == NULL || !opinfo->is_lease)
 			continue;
 
 		if (opinfo->o_lease->state != SMB2_OPLOCK_LEVEL_NONE) {
@@ -1361,6 +1362,9 @@ void smb_break_all_levII_oplock(struct ksmbd_work *work, struct ksmbd_file *fp,
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(brk_op, &ci->m_op_list, op_entry) {
+		if (brk_op->conn == NULL)
+			continue;
+
 		if (!atomic_inc_not_zero(&brk_op->refcount))
 			continue;
 
@@ -1496,11 +1500,10 @@ void create_lease_buf(u8 *rbuf, struct lease *lease)
 /**
  * parse_lease_state() - parse lease context containted in file open request
  * @open_req:	buffer containing smb2 file open(create) request
- * @is_dir:	whether leasing file is directory
  *
  * Return:  oplock state, -ENOENT if create lease context not found
  */
-struct lease_ctx_info *parse_lease_state(void *open_req, bool is_dir)
+struct lease_ctx_info *parse_lease_state(void *open_req)
 {
 	struct create_context *cc;
 	struct smb2_create_req *req = (struct smb2_create_req *)open_req;
@@ -1518,12 +1521,7 @@ struct lease_ctx_info *parse_lease_state(void *open_req, bool is_dir)
 		struct create_lease_v2 *lc = (struct create_lease_v2 *)cc;
 
 		memcpy(lreq->lease_key, lc->lcontext.LeaseKey, SMB2_LEASE_KEY_SIZE);
-		if (is_dir) {
-			lreq->req_state = lc->lcontext.LeaseState &
-				~SMB2_LEASE_WRITE_CACHING_LE;
-			lreq->is_dir = true;
-		} else
-			lreq->req_state = lc->lcontext.LeaseState;
+		lreq->req_state = lc->lcontext.LeaseState;
 		lreq->flags = lc->lcontext.LeaseFlags;
 		lreq->epoch = lc->lcontext.Epoch;
 		lreq->duration = lc->lcontext.LeaseDuration;
@@ -1646,6 +1644,8 @@ void create_durable_v2_rsp_buf(char *cc, struct ksmbd_file *fp)
 	buf->Name[3] = 'Q';
 
 	buf->Timeout = cpu_to_le32(fp->durable_timeout);
+	if (fp->is_persistent)
+		buf->Flags = cpu_to_le32(SMB2_DHANDLE_FLAG_PERSISTENT);
 }
 
 /**
@@ -1813,3 +1813,71 @@ struct oplock_info *lookup_lease_in_table(struct ksmbd_conn *conn,
 	read_unlock(&lease_list_lock);
 	return ret_op;
 }
+
+int smb2_check_durable_oplock(struct ksmbd_conn *conn,
+			      struct ksmbd_share_config *share,
+			      struct ksmbd_file *fp,
+			      struct lease_ctx_info *lctx,
+			      char *name)
+{
+	struct oplock_info *opinfo = opinfo_get(fp);
+	int ret = 0;
+
+	if (!opinfo)
+		return 0;
+
+	if (opinfo->is_lease == false) {
+		if (lctx) {
+			pr_err("create context include lease\n");
+			ret = -EBADF;
+			goto out;
+		}
+
+		if (opinfo->level != SMB2_OPLOCK_LEVEL_BATCH) {
+			pr_err("oplock level is not equal to SMB2_OPLOCK_LEVEL_BATCH\n");
+			ret = -EBADF;
+		}
+
+		goto out;
+	}
+
+	if (memcmp(conn->ClientGUID, fp->client_guid,
+				SMB2_CLIENT_GUID_SIZE)) {
+		ksmbd_debug(SMB, "Client guid of fp is not equal to the one of connction\n");
+		ret = -EBADF;
+		goto out;
+	}
+
+	if (!lctx) {
+		ksmbd_debug(SMB, "create context does not include lease\n");
+		ret = -EBADF;
+		goto out;
+	}
+
+	if (memcmp(opinfo->o_lease->lease_key, lctx->lease_key,
+				SMB2_LEASE_KEY_SIZE)) {
+		ksmbd_debug(SMB,
+			    "lease key of fp does not match lease key in create context\n");
+		ret = -EBADF;
+		goto out;
+	}
+
+	if (!(opinfo->o_lease->state & SMB2_LEASE_HANDLE_CACHING_LE)) {
+		ksmbd_debug(SMB, "lease state does not contain SMB2_LEASE_HANDLE_CACHING\n");
+		ret = -EBADF;
+		goto out;
+	}
+
+	if (opinfo->o_lease->version != lctx->version) {
+		ksmbd_debug(SMB,
+			    "lease version of fp does not match the one in create context\n");
+		ret = -EBADF;
+		goto out;
+	}
+
+	if (!ksmbd_inode_pending_delete(fp))
+		ret = ksmbd_validate_name_reconnect(share, fp, name);
+out:
+	opinfo_put(opinfo);
+	return ret;
+}

fs/smb/server/oplock.h

@@ -111,7 +111,7 @@ void opinfo_put(struct oplock_info *opinfo);
 
 /* Lease related functions */
 void create_lease_buf(u8 *rbuf, struct lease *lease);
-struct lease_ctx_info *parse_lease_state(void *open_req, bool is_dir);
+struct lease_ctx_info *parse_lease_state(void *open_req);
 __u8 smb2_map_lease_to_oplock(__le32 lease_state);
 int lease_read_to_write(struct oplock_info *opinfo);
 
@@ -130,4 +130,9 @@ void destroy_lease_table(struct ksmbd_conn *conn);
 void smb_send_parent_lease_break_noti(struct ksmbd_file *fp,
 				      struct lease_ctx_info *lctx);
 void smb_lazy_parent_lease_break_close(struct ksmbd_file *fp);
+int smb2_check_durable_oplock(struct ksmbd_conn *conn,
+			      struct ksmbd_share_config *share,
+			      struct ksmbd_file *fp,
+			      struct lease_ctx_info *lctx,
+			      char *name);
 #endif /* __KSMBD_OPLOCK_H */

fs/smb/server/smb2ops.c

@@ -256,6 +256,9 @@ void init_smb3_02_server(struct ksmbd_conn *conn)
 
 	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB3_MULTICHANNEL)
 		conn->vals->capabilities |= SMB2_GLOBAL_CAP_MULTI_CHANNEL;
+
+	if (server_conf.flags & KSMBD_GLOBAL_FLAG_DURABLE_HANDLE)
+		conn->vals->capabilities |= SMB2_GLOBAL_CAP_PERSISTENT_HANDLES;
 }
 
 /**
@@ -283,6 +286,9 @@ int init_smb3_11_server(struct ksmbd_conn *conn)
 	if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB3_MULTICHANNEL)
 		conn->vals->capabilities |= SMB2_GLOBAL_CAP_MULTI_CHANNEL;
 
+	if (server_conf.flags & KSMBD_GLOBAL_FLAG_DURABLE_HANDLE)
+		conn->vals->capabilities |= SMB2_GLOBAL_CAP_PERSISTENT_HANDLES;
+
 	INIT_LIST_HEAD(&conn->preauth_sess_table);
 	return 0;
 }