1 /* Service connection management
3 * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
12 #include <linux/slab.h>
13 #include "ar-internal.h"
16 * Find a service connection under RCU conditions.
18 * We could use a hash table, but that is subject to bucket stuffing by an
19 * attacker as the client gets to pick the epoch and cid values and would know
20 * the hash function. So, instead, we use a hash table for the peer and from
21 * that an rbtree to find the service connection. Under ordinary circumstances
22 * it might be slower than a large hash table, but it is at least limited in
25 struct rxrpc_connection *rxrpc_find_service_conn_rcu(struct rxrpc_peer *peer,
28 struct rxrpc_connection *conn = NULL;
29 struct rxrpc_conn_proto k;
30 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
34 k.epoch = sp->hdr.epoch;
35 k.cid = sp->hdr.cid & RXRPC_CIDMASK;
38 /* Unfortunately, rbtree walking doesn't give reliable results
39 * under just the RCU read lock, so we have to check for
42 read_seqbegin_or_lock(&peer->service_conn_lock, &seq);
44 p = rcu_dereference_raw(peer->service_conns.rb_node);
46 conn = rb_entry(p, struct rxrpc_connection, service_node);
48 if (conn->proto.index_key < k.index_key)
49 p = rcu_dereference_raw(p->rb_left);
50 else if (conn->proto.index_key > k.index_key)
51 p = rcu_dereference_raw(p->rb_right);
56 } while (need_seqretry(&peer->service_conn_lock, seq));
59 done_seqretry(&peer->service_conn_lock, seq);
60 _leave(" = %d", conn ? conn->debug_id : -1);
65 * Insert a service connection into a peer's tree, thereby making it a target
66 * for incoming packets.
68 static void rxrpc_publish_service_conn(struct rxrpc_peer *peer,
69 struct rxrpc_connection *conn)
71 struct rxrpc_connection *cursor = NULL;
72 struct rxrpc_conn_proto k = conn->proto;
73 struct rb_node **pp, *parent;
75 write_seqlock_bh(&peer->service_conn_lock);
77 pp = &peer->service_conns.rb_node;
81 cursor = rb_entry(parent,
82 struct rxrpc_connection, service_node);
84 if (cursor->proto.index_key < k.index_key)
86 else if (cursor->proto.index_key > k.index_key)
87 pp = &(*pp)->rb_right;
89 goto found_extant_conn;
92 rb_link_node_rcu(&conn->service_node, parent, pp);
93 rb_insert_color(&conn->service_node, &peer->service_conns);
95 set_bit(RXRPC_CONN_IN_SERVICE_CONNS, &conn->flags);
96 write_sequnlock_bh(&peer->service_conn_lock);
97 _leave(" = %d [new]", conn->debug_id);
101 if (atomic_read(&cursor->usage) == 0)
102 goto replace_old_connection;
103 write_sequnlock_bh(&peer->service_conn_lock);
104 /* We should not be able to get here. rxrpc_incoming_connection() is
105 * called in a non-reentrant context, so there can't be a race to
106 * insert a new connection.
110 replace_old_connection:
111 /* The old connection is from an outdated epoch. */
112 _debug("replace conn");
113 rb_replace_node_rcu(&cursor->service_node,
115 &peer->service_conns);
116 clear_bit(RXRPC_CONN_IN_SERVICE_CONNS, &cursor->flags);
121 * Preallocate a service connection. The connection is placed on the proc and
122 * reap lists so that we don't have to get the lock from BH context.
124 struct rxrpc_connection *rxrpc_prealloc_service_connection(struct rxrpc_net *rxnet,
127 struct rxrpc_connection *conn = rxrpc_alloc_connection(gfp);
130 /* We maintain an extra ref on the connection whilst it is on
131 * the rxrpc_connections list.
133 conn->state = RXRPC_CONN_SERVICE_PREALLOC;
134 atomic_set(&conn->usage, 2);
136 write_lock(&rxnet->conn_lock);
137 list_add_tail(&conn->link, &rxnet->service_conns);
138 list_add_tail(&conn->proc_link, &rxnet->conn_proc_list);
139 write_unlock(&rxnet->conn_lock);
141 trace_rxrpc_conn(conn, rxrpc_conn_new_service,
142 atomic_read(&conn->usage),
143 __builtin_return_address(0));
150 * Set up an incoming connection. This is called in BH context with the RCU
153 void rxrpc_new_incoming_connection(struct rxrpc_sock *rx,
154 struct rxrpc_connection *conn,
157 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
161 conn->proto.epoch = sp->hdr.epoch;
162 conn->proto.cid = sp->hdr.cid & RXRPC_CIDMASK;
163 conn->params.service_id = sp->hdr.serviceId;
164 conn->service_id = sp->hdr.serviceId;
165 conn->security_ix = sp->hdr.securityIndex;
166 conn->out_clientflag = 0;
167 if (conn->security_ix)
168 conn->state = RXRPC_CONN_SERVICE_UNSECURED;
170 conn->state = RXRPC_CONN_SERVICE;
172 /* See if we should upgrade the service. This can only happen on the
173 * first packet on a new connection. Once done, it applies to all
174 * subsequent calls on that connection.
176 if (sp->hdr.userStatus == RXRPC_USERSTATUS_SERVICE_UPGRADE &&
177 conn->service_id == rx->service_upgrade.from)
178 conn->service_id = rx->service_upgrade.to;
180 /* Make the connection a target for incoming packets. */
181 rxrpc_publish_service_conn(conn->params.peer, conn);
183 _net("CONNECTION new %d {%x}", conn->debug_id, conn->proto.cid);
187 * Remove the service connection from the peer's tree, thereby removing it as a
188 * target for incoming packets.
190 void rxrpc_unpublish_service_conn(struct rxrpc_connection *conn)
192 struct rxrpc_peer *peer = conn->params.peer;
194 write_seqlock_bh(&peer->service_conn_lock);
195 if (test_and_clear_bit(RXRPC_CONN_IN_SERVICE_CONNS, &conn->flags))
196 rb_erase(&conn->service_node, &peer->service_conns);
197 write_sequnlock_bh(&peer->service_conn_lock);