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- /* RxRPC remote transport endpoint record management
- *
- * Copyright (C) 2007, 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 License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
- */
- #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
- #include <linux/module.h>
- #include <linux/net.h>
- #include <linux/skbuff.h>
- #include <linux/udp.h>
- #include <linux/in.h>
- #include <linux/slab.h>
- #include <linux/hashtable.h>
- #include <net/sock.h>
- #include <net/af_rxrpc.h>
- #include <net/ip.h>
- #include <net/route.h>
- #include "ar-internal.h"
- static DEFINE_HASHTABLE(rxrpc_peer_hash, 10);
- static DEFINE_SPINLOCK(rxrpc_peer_hash_lock);
- /*
- * Hash a peer key.
- */
- static unsigned long rxrpc_peer_hash_key(struct rxrpc_local *local,
- const struct sockaddr_rxrpc *srx)
- {
- const u16 *p;
- unsigned int i, size;
- unsigned long hash_key;
- _enter("");
- hash_key = (unsigned long)local / __alignof__(*local);
- hash_key += srx->transport_type;
- hash_key += srx->transport_len;
- hash_key += srx->transport.family;
- switch (srx->transport.family) {
- case AF_INET:
- hash_key += (u16 __force)srx->transport.sin.sin_port;
- size = sizeof(srx->transport.sin.sin_addr);
- p = (u16 *)&srx->transport.sin.sin_addr;
- break;
- default:
- WARN(1, "AF_RXRPC: Unsupported transport address family\n");
- return 0;
- }
- /* Step through the peer address in 16-bit portions for speed */
- for (i = 0; i < size; i += sizeof(*p), p++)
- hash_key += *p;
- _leave(" 0x%lx", hash_key);
- return hash_key;
- }
- /*
- * Compare a peer to a key. Return -ve, 0 or +ve to indicate less than, same
- * or greater than.
- *
- * Unfortunately, the primitives in linux/hashtable.h don't allow for sorted
- * buckets and mid-bucket insertion, so we don't make full use of this
- * information at this point.
- */
- static long rxrpc_peer_cmp_key(const struct rxrpc_peer *peer,
- struct rxrpc_local *local,
- const struct sockaddr_rxrpc *srx,
- unsigned long hash_key)
- {
- long diff;
- diff = ((peer->hash_key - hash_key) ?:
- ((unsigned long)peer->local - (unsigned long)local) ?:
- (peer->srx.transport_type - srx->transport_type) ?:
- (peer->srx.transport_len - srx->transport_len) ?:
- (peer->srx.transport.family - srx->transport.family));
- if (diff != 0)
- return diff;
- switch (srx->transport.family) {
- case AF_INET:
- return ((u16 __force)peer->srx.transport.sin.sin_port -
- (u16 __force)srx->transport.sin.sin_port) ?:
- memcmp(&peer->srx.transport.sin.sin_addr,
- &srx->transport.sin.sin_addr,
- sizeof(struct in_addr));
- default:
- BUG();
- }
- }
- /*
- * Look up a remote transport endpoint for the specified address using RCU.
- */
- static struct rxrpc_peer *__rxrpc_lookup_peer_rcu(
- struct rxrpc_local *local,
- const struct sockaddr_rxrpc *srx,
- unsigned long hash_key)
- {
- struct rxrpc_peer *peer;
- hash_for_each_possible_rcu(rxrpc_peer_hash, peer, hash_link, hash_key) {
- if (rxrpc_peer_cmp_key(peer, local, srx, hash_key) == 0) {
- if (atomic_read(&peer->usage) == 0)
- return NULL;
- return peer;
- }
- }
- return NULL;
- }
- /*
- * Look up a remote transport endpoint for the specified address using RCU.
- */
- struct rxrpc_peer *rxrpc_lookup_peer_rcu(struct rxrpc_local *local,
- const struct sockaddr_rxrpc *srx)
- {
- struct rxrpc_peer *peer;
- unsigned long hash_key = rxrpc_peer_hash_key(local, srx);
- peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
- if (peer) {
- switch (srx->transport.family) {
- case AF_INET:
- _net("PEER %d {%d,%u,%pI4+%hu}",
- peer->debug_id,
- peer->srx.transport_type,
- peer->srx.transport.family,
- &peer->srx.transport.sin.sin_addr,
- ntohs(peer->srx.transport.sin.sin_port));
- break;
- }
- _leave(" = %p {u=%d}", peer, atomic_read(&peer->usage));
- }
- return peer;
- }
- /*
- * assess the MTU size for the network interface through which this peer is
- * reached
- */
- static void rxrpc_assess_MTU_size(struct rxrpc_peer *peer)
- {
- struct rtable *rt;
- struct flowi4 fl4;
- peer->if_mtu = 1500;
- rt = ip_route_output_ports(&init_net, &fl4, NULL,
- peer->srx.transport.sin.sin_addr.s_addr, 0,
- htons(7000), htons(7001),
- IPPROTO_UDP, 0, 0);
- if (IS_ERR(rt)) {
- _leave(" [route err %ld]", PTR_ERR(rt));
- return;
- }
- peer->if_mtu = dst_mtu(&rt->dst);
- dst_release(&rt->dst);
- _leave(" [if_mtu %u]", peer->if_mtu);
- }
- /*
- * Allocate a peer.
- */
- struct rxrpc_peer *rxrpc_alloc_peer(struct rxrpc_local *local, gfp_t gfp)
- {
- struct rxrpc_peer *peer;
- _enter("");
- peer = kzalloc(sizeof(struct rxrpc_peer), gfp);
- if (peer) {
- atomic_set(&peer->usage, 1);
- peer->local = local;
- INIT_HLIST_HEAD(&peer->error_targets);
- INIT_WORK(&peer->error_distributor,
- &rxrpc_peer_error_distributor);
- peer->service_conns = RB_ROOT;
- seqlock_init(&peer->service_conn_lock);
- spin_lock_init(&peer->lock);
- peer->debug_id = atomic_inc_return(&rxrpc_debug_id);
- }
- _leave(" = %p", peer);
- return peer;
- }
- /*
- * Set up a new peer.
- */
- static struct rxrpc_peer *rxrpc_create_peer(struct rxrpc_local *local,
- struct sockaddr_rxrpc *srx,
- unsigned long hash_key,
- gfp_t gfp)
- {
- struct rxrpc_peer *peer;
- _enter("");
- peer = rxrpc_alloc_peer(local, gfp);
- if (peer) {
- peer->hash_key = hash_key;
- memcpy(&peer->srx, srx, sizeof(*srx));
- rxrpc_assess_MTU_size(peer);
- peer->mtu = peer->if_mtu;
- if (srx->transport.family == AF_INET) {
- peer->hdrsize = sizeof(struct iphdr);
- switch (srx->transport_type) {
- case SOCK_DGRAM:
- peer->hdrsize += sizeof(struct udphdr);
- break;
- default:
- BUG();
- break;
- }
- } else {
- BUG();
- }
- peer->hdrsize += sizeof(struct rxrpc_wire_header);
- peer->maxdata = peer->mtu - peer->hdrsize;
- }
- _leave(" = %p", peer);
- return peer;
- }
- /*
- * obtain a remote transport endpoint for the specified address
- */
- struct rxrpc_peer *rxrpc_lookup_peer(struct rxrpc_local *local,
- struct sockaddr_rxrpc *srx, gfp_t gfp)
- {
- struct rxrpc_peer *peer, *candidate;
- unsigned long hash_key = rxrpc_peer_hash_key(local, srx);
- _enter("{%d,%d,%pI4+%hu}",
- srx->transport_type,
- srx->transport_len,
- &srx->transport.sin.sin_addr,
- ntohs(srx->transport.sin.sin_port));
- /* search the peer list first */
- rcu_read_lock();
- peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
- if (peer && !rxrpc_get_peer_maybe(peer))
- peer = NULL;
- rcu_read_unlock();
- if (!peer) {
- /* The peer is not yet present in hash - create a candidate
- * for a new record and then redo the search.
- */
- candidate = rxrpc_create_peer(local, srx, hash_key, gfp);
- if (!candidate) {
- _leave(" = NULL [nomem]");
- return NULL;
- }
- spin_lock(&rxrpc_peer_hash_lock);
- /* Need to check that we aren't racing with someone else */
- peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
- if (peer && !rxrpc_get_peer_maybe(peer))
- peer = NULL;
- if (!peer)
- hash_add_rcu(rxrpc_peer_hash,
- &candidate->hash_link, hash_key);
- spin_unlock(&rxrpc_peer_hash_lock);
- if (peer)
- kfree(candidate);
- else
- peer = candidate;
- }
- _net("PEER %d {%d,%pI4+%hu}",
- peer->debug_id,
- peer->srx.transport_type,
- &peer->srx.transport.sin.sin_addr,
- ntohs(peer->srx.transport.sin.sin_port));
- _leave(" = %p {u=%d}", peer, atomic_read(&peer->usage));
- return peer;
- }
- /*
- * Discard a ref on a remote peer record.
- */
- void __rxrpc_put_peer(struct rxrpc_peer *peer)
- {
- ASSERT(hlist_empty(&peer->error_targets));
- spin_lock(&rxrpc_peer_hash_lock);
- hash_del_rcu(&peer->hash_link);
- spin_unlock(&rxrpc_peer_hash_lock);
- kfree_rcu(peer, rcu);
- }
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