[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both

Provide AF_RXRPC sockets that can be used to talk to AFS servers, or serve
answers to AFS clients.  KerberosIV security is fully supported.  The patches
and some example test programs can be found in:

	http://people.redhat.com/~dhowells/rxrpc/

This will eventually replace the old implementation of kernel-only RxRPC
currently resident in net/rxrpc/.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 895 insertions, 0 deletions

diff --git a/net/rxrpc/ar-connection.c b/net/rxrpc/ar-connection.c
new file mode 100644
index 000000000000..01eb33c30571
--- /dev/null
+++ b/net/rxrpc/ar-connection.c
@@ -0,0 +1,895 @@
+/* RxRPC virtual connection handler
+ *
+ * Copyright (C) 2007 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 License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/net.h>
+#include <linux/skbuff.h>
+#include <linux/crypto.h>
+#include <net/sock.h>
+#include <net/af_rxrpc.h>
+#include "ar-internal.h"
+
+static void rxrpc_connection_reaper(struct work_struct *work);
+
+LIST_HEAD(rxrpc_connections);
+DEFINE_RWLOCK(rxrpc_connection_lock);
+static unsigned long rxrpc_connection_timeout = 10 * 60;
+static DECLARE_DELAYED_WORK(rxrpc_connection_reap, rxrpc_connection_reaper);
+
+/*
+ * allocate a new client connection bundle
+ */
+static struct rxrpc_conn_bundle *rxrpc_alloc_bundle(gfp_t gfp)
+{
+        struct rxrpc_conn_bundle *bundle;
+
+        _enter("");
+
+        bundle = kzalloc(sizeof(struct rxrpc_conn_bundle), gfp);
+        if (bundle) {
+                INIT_LIST_HEAD(&bundle->unused_conns);
+                INIT_LIST_HEAD(&bundle->avail_conns);
+                INIT_LIST_HEAD(&bundle->busy_conns);
+                init_waitqueue_head(&bundle->chanwait);
+                atomic_set(&bundle->usage, 1);
+        }
+
+        _leave(" = %p", bundle);
+        return bundle;
+}
+
+/*
+ * compare bundle parameters with what we're looking for
+ * - return -ve, 0 or +ve
+ */
+static inline
+int rxrpc_cmp_bundle(const struct rxrpc_conn_bundle *bundle,
+                     struct key *key, __be16 service_id)
+{
+        return (bundle->service_id - service_id) ?:
+                ((unsigned long) bundle->key - (unsigned long) key);
+}
+
+/*
+ * get bundle of client connections that a client socket can make use of
+ */
+struct rxrpc_conn_bundle *rxrpc_get_bundle(struct rxrpc_sock *rx,
+                                           struct rxrpc_transport *trans,
+                                           struct key *key,
+                                           __be16 service_id,
+                                           gfp_t gfp)
+{
+        struct rxrpc_conn_bundle *bundle, *candidate;
+        struct rb_node *p, *parent, **pp;
+
+        _enter("%p{%x},%x,%hx,",
+               rx, key_serial(key), trans->debug_id, ntohl(service_id));
+
+        if (rx->trans == trans && rx->bundle) {
+                atomic_inc(&rx->bundle->usage);
+                return rx->bundle;
+        }
+
+        /* search the extant bundles first for one that matches the specified
+         * user ID */
+        spin_lock(&trans->client_lock);
+
+        p = trans->bundles.rb_node;
+        while (p) {
+                bundle = rb_entry(p, struct rxrpc_conn_bundle, node);
+
+                if (rxrpc_cmp_bundle(bundle, key, service_id) < 0)
+                        p = p->rb_left;
+                else if (rxrpc_cmp_bundle(bundle, key, service_id) > 0)
+                        p = p->rb_right;
+                else
+                        goto found_extant_bundle;
+        }
+
+        spin_unlock(&trans->client_lock);
+
+        /* not yet present - create a candidate for a new record and then
+         * redo the search */
+        candidate = rxrpc_alloc_bundle(gfp);
+        if (!candidate) {
+                _leave(" = -ENOMEM");
+                return ERR_PTR(-ENOMEM);
+        }
+
+        candidate->key = key_get(key);
+        candidate->service_id = service_id;
+
+        spin_lock(&trans->client_lock);
+
+        pp = &trans->bundles.rb_node;
+        parent = NULL;
+        while (*pp) {
+                parent = *pp;
+                bundle = rb_entry(parent, struct rxrpc_conn_bundle, node);
+
+                if (rxrpc_cmp_bundle(bundle, key, service_id) < 0)
+                        pp = &(*pp)->rb_left;
+                else if (rxrpc_cmp_bundle(bundle, key, service_id) > 0)
+                        pp = &(*pp)->rb_right;
+                else
+                        goto found_extant_second;
+        }
+
+        /* second search also failed; add the new bundle */
+        bundle = candidate;
+        candidate = NULL;
+
+        rb_link_node(&bundle->node, parent, pp);
+        rb_insert_color(&bundle->node, &trans->bundles);
+        spin_unlock(&trans->client_lock);
+        _net("BUNDLE new on trans %d", trans->debug_id);
+        if (!rx->bundle && rx->sk.sk_state == RXRPC_CLIENT_CONNECTED) {
+                atomic_inc(&bundle->usage);
+                rx->bundle = bundle;
+        }
+        _leave(" = %p [new]", bundle);
+        return bundle;
+
+        /* we found the bundle in the list immediately */
+found_extant_bundle:
+        atomic_inc(&bundle->usage);
+        spin_unlock(&trans->client_lock);
+        _net("BUNDLE old on trans %d", trans->debug_id);
+        if (!rx->bundle && rx->sk.sk_state == RXRPC_CLIENT_CONNECTED) {
+                atomic_inc(&bundle->usage);
+                rx->bundle = bundle;
+        }
+        _leave(" = %p [extant %d]", bundle, atomic_read(&bundle->usage));
+        return bundle;
+
+        /* we found the bundle on the second time through the list */
+found_extant_second:
+        atomic_inc(&bundle->usage);
+        spin_unlock(&trans->client_lock);
+        kfree(candidate);
+        _net("BUNDLE old2 on trans %d", trans->debug_id);
+        if (!rx->bundle && rx->sk.sk_state == RXRPC_CLIENT_CONNECTED) {
+                atomic_inc(&bundle->usage);
+                rx->bundle = bundle;
+        }
+        _leave(" = %p [second %d]", bundle, atomic_read(&bundle->usage));
+        return bundle;
+}
+
+/*
+ * release a bundle
+ */
+void rxrpc_put_bundle(struct rxrpc_transport *trans,
+                      struct rxrpc_conn_bundle *bundle)
+{
+        _enter("%p,%p{%d}",trans, bundle, atomic_read(&bundle->usage));
+
+        if (atomic_dec_and_lock(&bundle->usage, &trans->client_lock)) {
+                _debug("Destroy bundle");
+                rb_erase(&bundle->node, &trans->bundles);
+                spin_unlock(&trans->client_lock);
+                ASSERT(list_empty(&bundle->unused_conns));
+                ASSERT(list_empty(&bundle->avail_conns));
+                ASSERT(list_empty(&bundle->busy_conns));
+                ASSERTCMP(bundle->num_conns, ==, 0);
+                key_put(bundle->key);
+                kfree(bundle);
+        }
+
+        _leave("");
+}
+
+/*
+ * allocate a new connection
+ */
+static struct rxrpc_connection *rxrpc_alloc_connection(gfp_t gfp)
+{
+        struct rxrpc_connection *conn;
+
+        _enter("");
+
+        conn = kzalloc(sizeof(struct rxrpc_connection), gfp);
+        if (conn) {
+                INIT_WORK(&conn->processor, &rxrpc_process_connection);
+                INIT_LIST_HEAD(&conn->bundle_link);
+                conn->calls = RB_ROOT;
+                skb_queue_head_init(&conn->rx_queue);
+                rwlock_init(&conn->lock);
+                spin_lock_init(&conn->state_lock);
+                atomic_set(&conn->usage, 1);
+                conn->debug_id = atomic_inc_return(&rxrpc_debug_id);
+                conn->avail_calls = RXRPC_MAXCALLS;
+                conn->size_align = 4;
+                conn->header_size = sizeof(struct rxrpc_header);
+        }
+
+        _leave(" = %p{%d}", conn, conn->debug_id);
+        return conn;
+}
+
+/*
+ * assign a connection ID to a connection and add it to the transport's
+ * connection lookup tree
+ * - called with transport client lock held
+ */
+static void rxrpc_assign_connection_id(struct rxrpc_connection *conn)
+{
+        struct rxrpc_connection *xconn;
+        struct rb_node *parent, **p;
+        __be32 epoch;
+        u32 real_conn_id;
+
+        _enter("");
+
+        epoch = conn->epoch;
+
+        write_lock_bh(&conn->trans->conn_lock);
+
+        conn->trans->conn_idcounter += RXRPC_CID_INC;
+        if (conn->trans->conn_idcounter < RXRPC_CID_INC)
+                conn->trans->conn_idcounter = RXRPC_CID_INC;
+        real_conn_id = conn->trans->conn_idcounter;
+
+attempt_insertion:
+        parent = NULL;
+        p = &conn->trans->client_conns.rb_node;
+
+        while (*p) {
+                parent = *p;
+                xconn = rb_entry(parent, struct rxrpc_connection, node);
+
+                if (epoch < xconn->epoch)
+                        p = &(*p)->rb_left;
+                else if (epoch > xconn->epoch)
+                        p = &(*p)->rb_right;
+                else if (real_conn_id < xconn->real_conn_id)
+                        p = &(*p)->rb_left;
+                else if (real_conn_id > xconn->real_conn_id)
+                        p = &(*p)->rb_right;
+                else
+                        goto id_exists;
+        }
+
+        /* we've found a suitable hole - arrange for this connection to occupy
+         * it */
+        rb_link_node(&conn->node, parent, p);
+        rb_insert_color(&conn->node, &conn->trans->client_conns);
+
+        conn->real_conn_id = real_conn_id;
+        conn->cid = htonl(real_conn_id);
+        write_unlock_bh(&conn->trans->conn_lock);
+        _leave(" [CONNID %x CID %x]", real_conn_id, ntohl(conn->cid));
+        return;
+
+        /* we found a connection with the proposed ID - walk the tree from that
+         * point looking for the next unused ID */
+id_exists:
+        for (;;) {
+                real_conn_id += RXRPC_CID_INC;
+                if (real_conn_id < RXRPC_CID_INC) {
+                        real_conn_id = RXRPC_CID_INC;
+                        conn->trans->conn_idcounter = real_conn_id;
+                        goto attempt_insertion;
+                }
+
+                parent = rb_next(parent);
+                if (!parent)
+                        goto attempt_insertion;
+
+                xconn = rb_entry(parent, struct rxrpc_connection, node);
+                if (epoch < xconn->epoch ||
+                    real_conn_id < xconn->real_conn_id)
+                        goto attempt_insertion;
+        }
+}
+
+/*
+ * add a call to a connection's call-by-ID tree
+ */
+static void rxrpc_add_call_ID_to_conn(struct rxrpc_connection *conn,
+                                      struct rxrpc_call *call)
+{
+        struct rxrpc_call *xcall;
+        struct rb_node *parent, **p;
+        __be32 call_id;
+
+        write_lock_bh(&conn->lock);
+
+        call_id = call->call_id;
+        p = &conn->calls.rb_node;
+        parent = NULL;
+        while (*p) {
+                parent = *p;
+                xcall = rb_entry(parent, struct rxrpc_call, conn_node);
+
+                if (call_id < xcall->call_id)
+                        p = &(*p)->rb_left;
+                else if (call_id > xcall->call_id)
+                        p = &(*p)->rb_right;
+                else
+                        BUG();
+        }
+
+        rb_link_node(&call->conn_node, parent, p);
+        rb_insert_color(&call->conn_node, &conn->calls);
+
+        write_unlock_bh(&conn->lock);
+}
+
+/*
+ * connect a call on an exclusive connection
+ */
+static int rxrpc_connect_exclusive(struct rxrpc_sock *rx,
+                                   struct rxrpc_transport *trans,
+                                   __be16 service_id,
+                                   struct rxrpc_call *call,
+                                   gfp_t gfp)
+{
+        struct rxrpc_connection *conn;
+        int chan, ret;
+
+        _enter("");
+
+        conn = rx->conn;
+        if (!conn) {
+                /* not yet present - create a candidate for a new connection
+                 * and then redo the check */
+                conn = rxrpc_alloc_connection(gfp);
+                if (IS_ERR(conn)) {
+                        _leave(" = %ld", PTR_ERR(conn));
+                        return PTR_ERR(conn);
+                }
+
+                conn->trans = trans;
+                conn->bundle = NULL;
+                conn->service_id = service_id;
+                conn->epoch = rxrpc_epoch;
+                conn->in_clientflag = 0;
+                conn->out_clientflag = RXRPC_CLIENT_INITIATED;
+                conn->cid = 0;
+                conn->state = RXRPC_CONN_CLIENT;
+                conn->avail_calls = RXRPC_MAXCALLS;
+                conn->security_level = rx->min_sec_level;
+                conn->key = key_get(rx->key);
+
+                ret = rxrpc_init_client_conn_security(conn);
+                if (ret < 0) {
+                        key_put(conn->key);
+                        kfree(conn);
+                        _leave(" = %d [key]", ret);
+                        return ret;
+                }
+
+                write_lock_bh(&rxrpc_connection_lock);
+                list_add_tail(&conn->link, &rxrpc_connections);
+                write_unlock_bh(&rxrpc_connection_lock);
+
+                spin_lock(&trans->client_lock);
+                atomic_inc(&trans->usage);
+
+                _net("CONNECT EXCL new %d on TRANS %d",
+                     conn->debug_id, conn->trans->debug_id);
+
+                rxrpc_assign_connection_id(conn);
+                rx->conn = conn;
+        }
+
+        /* we've got a connection with a free channel and we can now attach the
+         * call to it
+         * - we're holding the transport's client lock
+         * - we're holding a reference on the connection
+         */
+        for (chan = 0; chan < RXRPC_MAXCALLS; chan++)
+                if (!conn->channels[chan])
+                        goto found_channel;
+        goto no_free_channels;
+
+found_channel:
+        atomic_inc(&conn->usage);
+        conn->channels[chan] = call;
+        call->conn = conn;
+        call->channel = chan;
+        call->cid = conn->cid | htonl(chan);
+        call->call_id = htonl(++conn->call_counter);
+
+        _net("CONNECT client on conn %d chan %d as call %x",
+             conn->debug_id, chan, ntohl(call->call_id));
+
+        spin_unlock(&trans->client_lock);
+
+        rxrpc_add_call_ID_to_conn(conn, call);
+        _leave(" = 0");
+        return 0;
+
+no_free_channels:
+        spin_unlock(&trans->client_lock);
+        _leave(" = -ENOSR");
+        return -ENOSR;
+}
+
+/*
+ * find a connection for a call
+ * - called in process context with IRQs enabled
+ */
+int rxrpc_connect_call(struct rxrpc_sock *rx,
+                       struct rxrpc_transport *trans,
+                       struct rxrpc_conn_bundle *bundle,
+                       struct rxrpc_call *call,
+                       gfp_t gfp)
+{
+        struct rxrpc_connection *conn, *candidate;
+        int chan, ret;
+
+        DECLARE_WAITQUEUE(myself, current);
+
+        _enter("%p,%lx,", rx, call->user_call_ID);
+
+        if (test_bit(RXRPC_SOCK_EXCLUSIVE_CONN, &rx->flags))
+                return rxrpc_connect_exclusive(rx, trans, bundle->service_id,
+                                               call, gfp);
+
+        spin_lock(&trans->client_lock);
+        for (;;) {
+                /* see if the bundle has a call slot available */
+                if (!list_empty(&bundle->avail_conns)) {
+                        _debug("avail");
+                        conn = list_entry(bundle->avail_conns.next,
+                                          struct rxrpc_connection,
+                                          bundle_link);
+                        if (--conn->avail_calls == 0)
+                                list_move(&conn->bundle_link,
+                                          &bundle->busy_conns);
+                        atomic_inc(&conn->usage);
+                        break;
+                }
+
+                if (!list_empty(&bundle->unused_conns)) {
+                        _debug("unused");
+                        conn = list_entry(bundle->unused_conns.next,
+                                          struct rxrpc_connection,
+                                          bundle_link);
+                        atomic_inc(&conn->usage);
+                        list_move(&conn->bundle_link, &bundle->avail_conns);
+                        break;
+                }
+
+                /* need to allocate a new connection */
+                _debug("get new conn [%d]", bundle->num_conns);
+
+                spin_unlock(&trans->client_lock);
+
+                if (signal_pending(current))
+                        goto interrupted;
+
+                if (bundle->num_conns >= 20) {
+                        _debug("too many conns");
+
+                        if (!(gfp & __GFP_WAIT)) {
+                                _leave(" = -EAGAIN");
+                                return -EAGAIN;
+                        }
+
+                        add_wait_queue(&bundle->chanwait, &myself);
+                        for (;;) {
+                                set_current_state(TASK_INTERRUPTIBLE);
+                                if (bundle->num_conns < 20 ||
+                                    !list_empty(&bundle->unused_conns) ||
+                                    !list_empty(&bundle->avail_conns))
+                                        break;
+                                if (signal_pending(current))
+                                        goto interrupted_dequeue;
+                                schedule();
+                        }
+                        remove_wait_queue(&bundle->chanwait, &myself);
+                        __set_current_state(TASK_RUNNING);
+                        spin_lock(&trans->client_lock);
+                        continue;
+                }
+
+                /* not yet present - create a candidate for a new connection and then
+                 * redo the check */
+                candidate = rxrpc_alloc_connection(gfp);
+                if (IS_ERR(candidate)) {
+                        _leave(" = %ld", PTR_ERR(candidate));
+                        return PTR_ERR(candidate);
+                }
+
+                candidate->trans = trans;
+                candidate->bundle = bundle;
+                candidate->service_id = bundle->service_id;
+                candidate->epoch = rxrpc_epoch;
+                candidate->in_clientflag = 0;
+                candidate->out_clientflag = RXRPC_CLIENT_INITIATED;
+                candidate->cid = 0;
+                candidate->state = RXRPC_CONN_CLIENT;
+                candidate->avail_calls = RXRPC_MAXCALLS;
+                candidate->security_level = rx->min_sec_level;
+                candidate->key = key_get(rx->key);
+
+                ret = rxrpc_init_client_conn_security(candidate);
+                if (ret < 0) {
+                        key_put(candidate->key);
+                        kfree(candidate);
+                        _leave(" = %d [key]", ret);
+                        return ret;
+                }
+
+                write_lock_bh(&rxrpc_connection_lock);
+                list_add_tail(&candidate->link, &rxrpc_connections);
+                write_unlock_bh(&rxrpc_connection_lock);
+
+                spin_lock(&trans->client_lock);
+
+                list_add(&candidate->bundle_link, &bundle->unused_conns);
+                bundle->num_conns++;
+                atomic_inc(&bundle->usage);
+                atomic_inc(&trans->usage);
+
+                _net("CONNECT new %d on TRANS %d",
+                     candidate->debug_id, candidate->trans->debug_id);
+
+                rxrpc_assign_connection_id(candidate);
+                if (candidate->security)
+                        candidate->security->prime_packet_security(candidate);
+
+                /* leave the candidate lurking in zombie mode attached to the
+                 * bundle until we're ready for it */
+                rxrpc_put_connection(candidate);
+                candidate = NULL;
+        }
+
+        /* we've got a connection with a free channel and we can now attach the
+         * call to it
+         * - we're holding the transport's client lock
+         * - we're holding a reference on the connection
+         * - we're holding a reference on the bundle
+         */
+        for (chan = 0; chan < RXRPC_MAXCALLS; chan++)
+                if (!conn->channels[chan])
+                        goto found_channel;
+        BUG();
+
+found_channel:
+        conn->channels[chan] = call;
+        call->conn = conn;
+        call->channel = chan;
+        call->cid = conn->cid | htonl(chan);
+        call->call_id = htonl(++conn->call_counter);
+
+        _net("CONNECT client on conn %d chan %d as call %x",
+             conn->debug_id, chan, ntohl(call->call_id));
+
+        spin_unlock(&trans->client_lock);
+
+        rxrpc_add_call_ID_to_conn(conn, call);
+
+        _leave(" = 0");
+        return 0;
+
+interrupted_dequeue:
+        remove_wait_queue(&bundle->chanwait, &myself);
+        __set_current_state(TASK_RUNNING);
+interrupted:
+        _leave(" = -ERESTARTSYS");
+        return -ERESTARTSYS;
+}
+
+/*
+ * get a record of an incoming connection
+ */
+struct rxrpc_connection *
+rxrpc_incoming_connection(struct rxrpc_transport *trans,
+                          struct rxrpc_header *hdr,
+                          gfp_t gfp)
+{
+        struct rxrpc_connection *conn, *candidate = NULL;
+        struct rb_node *p, **pp;
+        const char *new = "old";
+        __be32 epoch;
+        u32 conn_id;
+
+        _enter("");
+
+        ASSERT(hdr->flags & RXRPC_CLIENT_INITIATED);
+
+        epoch = hdr->epoch;
+        conn_id = ntohl(hdr->cid) & RXRPC_CIDMASK;
+
+        /* search the connection list first */
+        read_lock_bh(&trans->conn_lock);
+
+        p = trans->server_conns.rb_node;
+        while (p) {
+                conn = rb_entry(p, struct rxrpc_connection, node);
+
+                _debug("maybe %x", conn->real_conn_id);
+
+                if (epoch < conn->epoch)
+                        p = p->rb_left;
+                else if (epoch > conn->epoch)
+                        p = p->rb_right;
+                else if (conn_id < conn->real_conn_id)
+                        p = p->rb_left;
+                else if (conn_id > conn->real_conn_id)
+                        p = p->rb_right;
+                else
+                        goto found_extant_connection;
+        }
+        read_unlock_bh(&trans->conn_lock);
+
+        /* not yet present - create a candidate for a new record and then
+         * redo the search */
+        candidate = rxrpc_alloc_connection(gfp);
+        if (!candidate) {
+                _leave(" = -ENOMEM");
+                return ERR_PTR(-ENOMEM);
+        }
+
+        candidate->trans = trans;
+        candidate->epoch = hdr->epoch;
+        candidate->cid = hdr->cid & __constant_cpu_to_be32(RXRPC_CIDMASK);
+        candidate->service_id = hdr->serviceId;
+        candidate->security_ix = hdr->securityIndex;
+        candidate->in_clientflag = RXRPC_CLIENT_INITIATED;
+        candidate->out_clientflag = 0;
+        candidate->real_conn_id = conn_id;
+        candidate->state = RXRPC_CONN_SERVER;
+        if (candidate->service_id)
+                candidate->state = RXRPC_CONN_SERVER_UNSECURED;
+
+        write_lock_bh(&trans->conn_lock);
+
+        pp = &trans->server_conns.rb_node;
+        p = NULL;
+        while (*pp) {
+                p = *pp;
+                conn = rb_entry(p, struct rxrpc_connection, node);
+
+                if (epoch < conn->epoch)
+                        pp = &(*pp)->rb_left;
+                else if (epoch > conn->epoch)
+                        pp = &(*pp)->rb_right;
+                else if (conn_id < conn->real_conn_id)
+                        pp = &(*pp)->rb_left;
+                else if (conn_id > conn->real_conn_id)
+                        pp = &(*pp)->rb_right;
+                else
+                        goto found_extant_second;
+        }
+
+        /* we can now add the new candidate to the list */
+        conn = candidate;
+        candidate = NULL;
+        rb_link_node(&conn->node, p, pp);
+        rb_insert_color(&conn->node, &trans->server_conns);
+        atomic_inc(&conn->trans->usage);
+
+        write_unlock_bh(&trans->conn_lock);
+
+        write_lock_bh(&rxrpc_connection_lock);
+        list_add_tail(&conn->link, &rxrpc_connections);
+        write_unlock_bh(&rxrpc_connection_lock);
+
+        new = "new";
+
+success:
+        _net("CONNECTION %s %d {%x}", new, conn->debug_id, conn->real_conn_id);
+
+        _leave(" = %p {u=%d}", conn, atomic_read(&conn->usage));
+        return conn;
+
+        /* we found the connection in the list immediately */
+found_extant_connection:
+        if (hdr->securityIndex != conn->security_ix) {
+                read_unlock_bh(&trans->conn_lock);
+                goto security_mismatch;
+        }
+        atomic_inc(&conn->usage);
+        read_unlock_bh(&trans->conn_lock);
+        goto success;
+
+        /* we found the connection on the second time through the list */
+found_extant_second:
+        if (hdr->securityIndex != conn->security_ix) {
+                write_unlock_bh(&trans->conn_lock);
+                goto security_mismatch;
+        }
+        atomic_inc(&conn->usage);
+        write_unlock_bh(&trans->conn_lock);
+        kfree(candidate);
+        goto success;
+
+security_mismatch:
+        kfree(candidate);
+        _leave(" = -EKEYREJECTED");
+        return ERR_PTR(-EKEYREJECTED);
+}
+
+/*
+ * find a connection based on transport and RxRPC connection ID for an incoming
+ * packet
+ */
+struct rxrpc_connection *rxrpc_find_connection(struct rxrpc_transport *trans,
+                                               struct rxrpc_header *hdr)
+{
+        struct rxrpc_connection *conn;
+        struct rb_node *p;
+        __be32 epoch;
+        u32 conn_id;
+
+        _enter(",{%x,%x}", ntohl(hdr->cid), hdr->flags);
+
+        read_lock_bh(&trans->conn_lock);
+
+        conn_id = ntohl(hdr->cid) & RXRPC_CIDMASK;
+        epoch = hdr->epoch;
+
+        if (hdr->flags & RXRPC_CLIENT_INITIATED)
+                p = trans->server_conns.rb_node;
+        else
+                p = trans->client_conns.rb_node;
+
+        while (p) {
+                conn = rb_entry(p, struct rxrpc_connection, node);
+
+                _debug("maybe %x", conn->real_conn_id);
+
+                if (epoch < conn->epoch)
+                        p = p->rb_left;
+                else if (epoch > conn->epoch)
+                        p = p->rb_right;
+                else if (conn_id < conn->real_conn_id)
+                        p = p->rb_left;
+                else if (conn_id > conn->real_conn_id)
+                        p = p->rb_right;
+                else
+                        goto found;
+        }
+
+        read_unlock_bh(&trans->conn_lock);
+        _leave(" = NULL");
+        return NULL;
+
+found:
+        atomic_inc(&conn->usage);
+        read_unlock_bh(&trans->conn_lock);
+        _leave(" = %p", conn);
+        return conn;
+}
+
+/*
+ * release a virtual connection
+ */
+void rxrpc_put_connection(struct rxrpc_connection *conn)
+{
+        _enter("%p{u=%d,d=%d}",
+               conn, atomic_read(&conn->usage), conn->debug_id);
+
+        ASSERTCMP(atomic_read(&conn->usage), >, 0);
+
+        conn->put_time = xtime.tv_sec;
+        if (atomic_dec_and_test(&conn->usage)) {
+                _debug("zombie");
+                schedule_delayed_work(&rxrpc_connection_reap, 0);
+        }
+
+        _leave("");
+}
+
+/*
+ * destroy a virtual connection
+ */
+static void rxrpc_destroy_connection(struct rxrpc_connection *conn)
+{
+        _enter("%p{%d}", conn, atomic_read(&conn->usage));
+
+        ASSERTCMP(atomic_read(&conn->usage), ==, 0);
+
+        _net("DESTROY CONN %d", conn->debug_id);
+
+        if (conn->bundle)
+                rxrpc_put_bundle(conn->trans, conn->bundle);
+
+        ASSERT(RB_EMPTY_ROOT(&conn->calls));
+        rxrpc_purge_queue(&conn->rx_queue);
+
+        rxrpc_clear_conn_security(conn);
+        rxrpc_put_transport(conn->trans);
+        kfree(conn);
+        _leave("");
+}
+
+/*
+ * reap dead connections
+ */
+void rxrpc_connection_reaper(struct work_struct *work)
+{
+        struct rxrpc_connection *conn, *_p;
+        unsigned long now, earliest, reap_time;
+
+        LIST_HEAD(graveyard);
+
+        _enter("");
+
+        now = xtime.tv_sec;
+        earliest = ULONG_MAX;
+
+        write_lock_bh(&rxrpc_connection_lock);
+        list_for_each_entry_safe(conn, _p, &rxrpc_connections, link) {
+                _debug("reap CONN %d { u=%d,t=%ld }",
+                       conn->debug_id, atomic_read(&conn->usage),
+                       (long) now - (long) conn->put_time);
+
+                if (likely(atomic_read(&conn->usage) > 0))
+                        continue;
+
+                spin_lock(&conn->trans->client_lock);
+                write_lock(&conn->trans->conn_lock);
+                reap_time = conn->put_time + rxrpc_connection_timeout;
+
+                if (atomic_read(&conn->usage) > 0) {
+                        ;
+                } else if (reap_time <= now) {
+                        list_move_tail(&conn->link, &graveyard);
+                        if (conn->out_clientflag)
+                                rb_erase(&conn->node,
+                                         &conn->trans->client_conns);
+                        else
+                                rb_erase(&conn->node,
+                                         &conn->trans->server_conns);
+                        if (conn->bundle) {
+                                list_del_init(&conn->bundle_link);
+                                conn->bundle->num_conns--;
+                        }
+
+                } else if (reap_time < earliest) {
+                        earliest = reap_time;
+                }
+
+                write_unlock(&conn->trans->conn_lock);
+                spin_unlock(&conn->trans->client_lock);
+        }
+        write_unlock_bh(&rxrpc_connection_lock);
+
+        if (earliest != ULONG_MAX) {
+                _debug("reschedule reaper %ld", (long) earliest - now);
+                ASSERTCMP(earliest, >, now);
+                schedule_delayed_work(&rxrpc_connection_reap,
+                                      (earliest - now) * HZ);
+        }
+
+        /* then destroy all those pulled out */
+        while (!list_empty(&graveyard)) {
+                conn = list_entry(graveyard.next, struct rxrpc_connection,
+                                  link);
+                list_del_init(&conn->link);
+
+                ASSERTCMP(atomic_read(&conn->usage), ==, 0);
+                rxrpc_destroy_connection(conn);
+        }
+
+        _leave("");
+}
+
+/*
+ * preemptively destroy all the connection records rather than waiting for them
+ * to time out
+ */
+void __exit rxrpc_destroy_all_connections(void)
+{
+        _enter("");
+
+        rxrpc_connection_timeout = 0;
+        cancel_delayed_work(&rxrpc_connection_reap);
+        schedule_delayed_work(&rxrpc_connection_reap, 0);
+
+        _leave("");
+}