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-rw-r--r--net/rxrpc/conn_service.c230
1 files changed, 230 insertions, 0 deletions
diff --git a/net/rxrpc/conn_service.c b/net/rxrpc/conn_service.c
new file mode 100644
index 000000000000..fd9027ccba8f
--- /dev/null
+++ b/net/rxrpc/conn_service.c
@@ -0,0 +1,230 @@
+/* Service connection management
+ *
+ * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/slab.h>
+#include "ar-internal.h"
+
+/*
+ * Find a service connection under RCU conditions.
+ *
+ * We could use a hash table, but that is subject to bucket stuffing by an
+ * attacker as the client gets to pick the epoch and cid values and would know
+ * the hash function. So, instead, we use a hash table for the peer and from
+ * that an rbtree to find the service connection. Under ordinary circumstances
+ * it might be slower than a large hash table, but it is at least limited in
+ * depth.
+ */
+struct rxrpc_connection *rxrpc_find_service_conn_rcu(struct rxrpc_peer *peer,
+ struct sk_buff *skb)
+{
+ struct rxrpc_connection *conn = NULL;
+ struct rxrpc_conn_proto k;
+ struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+ struct rb_node *p;
+ unsigned int seq = 0;
+
+ k.epoch = sp->hdr.epoch;
+ k.cid = sp->hdr.cid & RXRPC_CIDMASK;
+
+ do {
+ /* Unfortunately, rbtree walking doesn't give reliable results
+ * under just the RCU read lock, so we have to check for
+ * changes.
+ */
+ read_seqbegin_or_lock(&peer->service_conn_lock, &seq);
+
+ p = rcu_dereference_raw(peer->service_conns.rb_node);
+ while (p) {
+ conn = rb_entry(p, struct rxrpc_connection, service_node);
+
+ if (conn->proto.index_key < k.index_key)
+ p = rcu_dereference_raw(p->rb_left);
+ else if (conn->proto.index_key > k.index_key)
+ p = rcu_dereference_raw(p->rb_right);
+ else
+ goto done;
+ conn = NULL;
+ }
+ } while (need_seqretry(&peer->service_conn_lock, seq));
+
+done:
+ done_seqretry(&peer->service_conn_lock, seq);
+ _leave(" = %d", conn ? conn->debug_id : -1);
+ return conn;
+}
+
+/*
+ * Insert a service connection into a peer's tree, thereby making it a target
+ * for incoming packets.
+ */
+static struct rxrpc_connection *
+rxrpc_publish_service_conn(struct rxrpc_peer *peer,
+ struct rxrpc_connection *conn)
+{
+ struct rxrpc_connection *cursor = NULL;
+ struct rxrpc_conn_proto k = conn->proto;
+ struct rb_node **pp, *parent;
+
+ write_seqlock_bh(&peer->service_conn_lock);
+
+ pp = &peer->service_conns.rb_node;
+ parent = NULL;
+ while (*pp) {
+ parent = *pp;
+ cursor = rb_entry(parent,
+ struct rxrpc_connection, service_node);
+
+ if (cursor->proto.index_key < k.index_key)
+ pp = &(*pp)->rb_left;
+ else if (cursor->proto.index_key > k.index_key)
+ pp = &(*pp)->rb_right;
+ else
+ goto found_extant_conn;
+ }
+
+ rb_link_node_rcu(&conn->service_node, parent, pp);
+ rb_insert_color(&conn->service_node, &peer->service_conns);
+conn_published:
+ set_bit(RXRPC_CONN_IN_SERVICE_CONNS, &conn->flags);
+ write_sequnlock_bh(&peer->service_conn_lock);
+ _leave(" = %d [new]", conn->debug_id);
+ return conn;
+
+found_extant_conn:
+ if (atomic_read(&cursor->usage) == 0)
+ goto replace_old_connection;
+ write_sequnlock_bh(&peer->service_conn_lock);
+ /* We should not be able to get here. rxrpc_incoming_connection() is
+ * called in a non-reentrant context, so there can't be a race to
+ * insert a new connection.
+ */
+ BUG();
+
+replace_old_connection:
+ /* The old connection is from an outdated epoch. */
+ _debug("replace conn");
+ rb_replace_node_rcu(&cursor->service_node,
+ &conn->service_node,
+ &peer->service_conns);
+ clear_bit(RXRPC_CONN_IN_SERVICE_CONNS, &cursor->flags);
+ goto conn_published;
+}
+
+/*
+ * get a record of an incoming connection
+ */
+struct rxrpc_connection *rxrpc_incoming_connection(struct rxrpc_local *local,
+ struct sockaddr_rxrpc *srx,
+ struct sk_buff *skb)
+{
+ struct rxrpc_connection *conn;
+ struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+ struct rxrpc_peer *peer;
+ const char *new = "old";
+
+ _enter("");
+
+ peer = rxrpc_lookup_peer(local, srx, GFP_NOIO);
+ if (!peer) {
+ _debug("no peer");
+ return ERR_PTR(-EBUSY);
+ }
+
+ ASSERT(sp->hdr.flags & RXRPC_CLIENT_INITIATED);
+
+ rcu_read_lock();
+ peer = rxrpc_lookup_peer_rcu(local, srx);
+ if (peer) {
+ conn = rxrpc_find_service_conn_rcu(peer, skb);
+ if (conn) {
+ if (sp->hdr.securityIndex != conn->security_ix)
+ goto security_mismatch_rcu;
+ if (rxrpc_get_connection_maybe(conn))
+ goto found_extant_connection_rcu;
+
+ /* The conn has expired but we can't remove it without
+ * the appropriate lock, so we attempt to replace it
+ * when we have a new candidate.
+ */
+ }
+
+ if (!rxrpc_get_peer_maybe(peer))
+ peer = NULL;
+ }
+ rcu_read_unlock();
+
+ if (!peer) {
+ peer = rxrpc_lookup_peer(local, srx, GFP_NOIO);
+ if (!peer)
+ goto enomem;
+ }
+
+ /* We don't have a matching record yet. */
+ conn = rxrpc_alloc_connection(GFP_NOIO);
+ if (!conn)
+ goto enomem_peer;
+
+ conn->proto.epoch = sp->hdr.epoch;
+ conn->proto.cid = sp->hdr.cid & RXRPC_CIDMASK;
+ conn->params.local = local;
+ conn->params.peer = peer;
+ conn->params.service_id = sp->hdr.serviceId;
+ conn->security_ix = sp->hdr.securityIndex;
+ conn->out_clientflag = 0;
+ conn->state = RXRPC_CONN_SERVICE;
+ if (conn->params.service_id)
+ conn->state = RXRPC_CONN_SERVICE_UNSECURED;
+
+ rxrpc_get_local(local);
+
+ write_lock(&rxrpc_connection_lock);
+ list_add_tail(&conn->link, &rxrpc_connections);
+ write_unlock(&rxrpc_connection_lock);
+
+ /* Make the connection a target for incoming packets. */
+ rxrpc_publish_service_conn(peer, conn);
+
+ new = "new";
+
+success:
+ _net("CONNECTION %s %d {%x}", new, conn->debug_id, conn->proto.cid);
+ _leave(" = %p {u=%d}", conn, atomic_read(&conn->usage));
+ return conn;
+
+found_extant_connection_rcu:
+ rcu_read_unlock();
+ goto success;
+
+security_mismatch_rcu:
+ rcu_read_unlock();
+ _leave(" = -EKEYREJECTED");
+ return ERR_PTR(-EKEYREJECTED);
+
+enomem_peer:
+ rxrpc_put_peer(peer);
+enomem:
+ _leave(" = -ENOMEM");
+ return ERR_PTR(-ENOMEM);
+}
+
+/*
+ * Remove the service connection from the peer's tree, thereby removing it as a
+ * target for incoming packets.
+ */
+void rxrpc_unpublish_service_conn(struct rxrpc_connection *conn)
+{
+ struct rxrpc_peer *peer = conn->params.peer;
+
+ write_seqlock_bh(&peer->service_conn_lock);
+ if (test_and_clear_bit(RXRPC_CONN_IN_SERVICE_CONNS, &conn->flags))
+ rb_erase(&conn->service_node, &peer->service_conns);
+ write_sequnlock_bh(&peer->service_conn_lock);
+}