diff options
Diffstat (limited to 'net/rxrpc/peer_object.c')
| -rw-r--r-- | net/rxrpc/peer_object.c | 315 |
1 files changed, 315 insertions, 0 deletions
diff --git a/net/rxrpc/peer_object.c b/net/rxrpc/peer_object.c new file mode 100644 index 000000000000..538e9831c699 --- /dev/null +++ b/net/rxrpc/peer_object.c @@ -0,0 +1,315 @@ +/* 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); +} |