David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 1 | /* Service connection management |
| 2 | * |
| 3 | * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved. |
| 4 | * Written by David Howells (dhowells@redhat.com) |
| 5 | * |
| 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. |
| 10 | */ |
| 11 | |
| 12 | #include <linux/slab.h> |
| 13 | #include "ar-internal.h" |
| 14 | |
| 15 | /* |
David Howells | 8496af5 | 2016-07-01 07:51:50 +0100 | [diff] [blame] | 16 | * Find a service connection under RCU conditions. |
| 17 | * |
| 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 |
| 23 | * depth. |
| 24 | */ |
| 25 | struct rxrpc_connection *rxrpc_find_service_conn_rcu(struct rxrpc_peer *peer, |
| 26 | struct sk_buff *skb) |
| 27 | { |
| 28 | struct rxrpc_connection *conn = NULL; |
| 29 | struct rxrpc_conn_proto k; |
| 30 | struct rxrpc_skb_priv *sp = rxrpc_skb(skb); |
| 31 | struct rb_node *p; |
| 32 | unsigned int seq = 0; |
| 33 | |
| 34 | k.epoch = sp->hdr.epoch; |
| 35 | k.cid = sp->hdr.cid & RXRPC_CIDMASK; |
| 36 | |
| 37 | do { |
| 38 | /* Unfortunately, rbtree walking doesn't give reliable results |
| 39 | * under just the RCU read lock, so we have to check for |
| 40 | * changes. |
| 41 | */ |
| 42 | read_seqbegin_or_lock(&peer->service_conn_lock, &seq); |
| 43 | |
| 44 | p = rcu_dereference_raw(peer->service_conns.rb_node); |
| 45 | while (p) { |
| 46 | conn = rb_entry(p, struct rxrpc_connection, service_node); |
| 47 | |
| 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); |
| 52 | else |
| 53 | goto done; |
| 54 | conn = NULL; |
| 55 | } |
| 56 | } while (need_seqretry(&peer->service_conn_lock, seq)); |
| 57 | |
| 58 | done: |
| 59 | done_seqretry(&peer->service_conn_lock, seq); |
| 60 | _leave(" = %d", conn ? conn->debug_id : -1); |
| 61 | return conn; |
| 62 | } |
| 63 | |
| 64 | /* |
| 65 | * Insert a service connection into a peer's tree, thereby making it a target |
| 66 | * for incoming packets. |
| 67 | */ |
| 68 | static struct rxrpc_connection * |
| 69 | rxrpc_publish_service_conn(struct rxrpc_peer *peer, |
| 70 | struct rxrpc_connection *conn) |
| 71 | { |
| 72 | struct rxrpc_connection *cursor = NULL; |
| 73 | struct rxrpc_conn_proto k = conn->proto; |
| 74 | struct rb_node **pp, *parent; |
| 75 | |
| 76 | write_seqlock_bh(&peer->service_conn_lock); |
| 77 | |
| 78 | pp = &peer->service_conns.rb_node; |
| 79 | parent = NULL; |
| 80 | while (*pp) { |
| 81 | parent = *pp; |
| 82 | cursor = rb_entry(parent, |
| 83 | struct rxrpc_connection, service_node); |
| 84 | |
| 85 | if (cursor->proto.index_key < k.index_key) |
| 86 | pp = &(*pp)->rb_left; |
| 87 | else if (cursor->proto.index_key > k.index_key) |
| 88 | pp = &(*pp)->rb_right; |
| 89 | else |
| 90 | goto found_extant_conn; |
| 91 | } |
| 92 | |
| 93 | rb_link_node_rcu(&conn->service_node, parent, pp); |
| 94 | rb_insert_color(&conn->service_node, &peer->service_conns); |
| 95 | conn_published: |
| 96 | set_bit(RXRPC_CONN_IN_SERVICE_CONNS, &conn->flags); |
| 97 | write_sequnlock_bh(&peer->service_conn_lock); |
| 98 | _leave(" = %d [new]", conn->debug_id); |
| 99 | return conn; |
| 100 | |
| 101 | found_extant_conn: |
| 102 | if (atomic_read(&cursor->usage) == 0) |
| 103 | goto replace_old_connection; |
| 104 | write_sequnlock_bh(&peer->service_conn_lock); |
| 105 | /* We should not be able to get here. rxrpc_incoming_connection() is |
| 106 | * called in a non-reentrant context, so there can't be a race to |
| 107 | * insert a new connection. |
| 108 | */ |
| 109 | BUG(); |
| 110 | |
| 111 | replace_old_connection: |
| 112 | /* The old connection is from an outdated epoch. */ |
| 113 | _debug("replace conn"); |
| 114 | rb_replace_node_rcu(&cursor->service_node, |
| 115 | &conn->service_node, |
| 116 | &peer->service_conns); |
| 117 | clear_bit(RXRPC_CONN_IN_SERVICE_CONNS, &cursor->flags); |
| 118 | goto conn_published; |
| 119 | } |
| 120 | |
| 121 | /* |
David Howells | 00e9071 | 2016-09-08 11:10:12 +0100 | [diff] [blame^] | 122 | * Preallocate a service connection. The connection is placed on the proc and |
| 123 | * reap lists so that we don't have to get the lock from BH context. |
| 124 | */ |
| 125 | struct rxrpc_connection *rxrpc_prealloc_service_connection(gfp_t gfp) |
| 126 | { |
| 127 | struct rxrpc_connection *conn = rxrpc_alloc_connection(gfp); |
| 128 | |
| 129 | if (conn) { |
| 130 | /* We maintain an extra ref on the connection whilst it is on |
| 131 | * the rxrpc_connections list. |
| 132 | */ |
| 133 | conn->state = RXRPC_CONN_SERVICE_PREALLOC; |
| 134 | atomic_set(&conn->usage, 2); |
| 135 | |
| 136 | write_lock(&rxrpc_connection_lock); |
| 137 | list_add_tail(&conn->link, &rxrpc_connections); |
| 138 | list_add_tail(&conn->proc_link, &rxrpc_connection_proc_list); |
| 139 | write_unlock(&rxrpc_connection_lock); |
| 140 | } |
| 141 | |
| 142 | return conn; |
| 143 | } |
| 144 | |
| 145 | /* |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 146 | * get a record of an incoming connection |
| 147 | */ |
| 148 | struct rxrpc_connection *rxrpc_incoming_connection(struct rxrpc_local *local, |
David Howells | d991b4a | 2016-06-29 14:40:39 +0100 | [diff] [blame] | 149 | struct sockaddr_rxrpc *srx, |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 150 | struct sk_buff *skb) |
| 151 | { |
David Howells | 8496af5 | 2016-07-01 07:51:50 +0100 | [diff] [blame] | 152 | struct rxrpc_connection *conn; |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 153 | struct rxrpc_skb_priv *sp = rxrpc_skb(skb); |
David Howells | d991b4a | 2016-06-29 14:40:39 +0100 | [diff] [blame] | 154 | struct rxrpc_peer *peer; |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 155 | const char *new = "old"; |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 156 | |
| 157 | _enter(""); |
| 158 | |
David Howells | d991b4a | 2016-06-29 14:40:39 +0100 | [diff] [blame] | 159 | peer = rxrpc_lookup_peer(local, srx, GFP_NOIO); |
| 160 | if (!peer) { |
| 161 | _debug("no peer"); |
| 162 | return ERR_PTR(-EBUSY); |
| 163 | } |
| 164 | |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 165 | ASSERT(sp->hdr.flags & RXRPC_CLIENT_INITIATED); |
| 166 | |
David Howells | 8496af5 | 2016-07-01 07:51:50 +0100 | [diff] [blame] | 167 | rcu_read_lock(); |
| 168 | peer = rxrpc_lookup_peer_rcu(local, srx); |
| 169 | if (peer) { |
| 170 | conn = rxrpc_find_service_conn_rcu(peer, skb); |
| 171 | if (conn) { |
| 172 | if (sp->hdr.securityIndex != conn->security_ix) |
| 173 | goto security_mismatch_rcu; |
| 174 | if (rxrpc_get_connection_maybe(conn)) |
| 175 | goto found_extant_connection_rcu; |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 176 | |
David Howells | 8496af5 | 2016-07-01 07:51:50 +0100 | [diff] [blame] | 177 | /* The conn has expired but we can't remove it without |
| 178 | * the appropriate lock, so we attempt to replace it |
| 179 | * when we have a new candidate. |
| 180 | */ |
| 181 | } |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 182 | |
David Howells | 8496af5 | 2016-07-01 07:51:50 +0100 | [diff] [blame] | 183 | if (!rxrpc_get_peer_maybe(peer)) |
| 184 | peer = NULL; |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 185 | } |
David Howells | 8496af5 | 2016-07-01 07:51:50 +0100 | [diff] [blame] | 186 | rcu_read_unlock(); |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 187 | |
David Howells | 8496af5 | 2016-07-01 07:51:50 +0100 | [diff] [blame] | 188 | if (!peer) { |
| 189 | peer = rxrpc_lookup_peer(local, srx, GFP_NOIO); |
Dan Carpenter | 7acef60 | 2016-07-14 15:47:01 +0100 | [diff] [blame] | 190 | if (!peer) |
David Howells | 8496af5 | 2016-07-01 07:51:50 +0100 | [diff] [blame] | 191 | goto enomem; |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 192 | } |
| 193 | |
David Howells | 8496af5 | 2016-07-01 07:51:50 +0100 | [diff] [blame] | 194 | /* We don't have a matching record yet. */ |
| 195 | conn = rxrpc_alloc_connection(GFP_NOIO); |
| 196 | if (!conn) |
| 197 | goto enomem_peer; |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 198 | |
David Howells | 8496af5 | 2016-07-01 07:51:50 +0100 | [diff] [blame] | 199 | conn->proto.epoch = sp->hdr.epoch; |
| 200 | conn->proto.cid = sp->hdr.cid & RXRPC_CIDMASK; |
| 201 | conn->params.local = local; |
| 202 | conn->params.peer = peer; |
| 203 | conn->params.service_id = sp->hdr.serviceId; |
| 204 | conn->security_ix = sp->hdr.securityIndex; |
| 205 | conn->out_clientflag = 0; |
| 206 | conn->state = RXRPC_CONN_SERVICE; |
| 207 | if (conn->params.service_id) |
| 208 | conn->state = RXRPC_CONN_SERVICE_UNSECURED; |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 209 | |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 210 | rxrpc_get_local(local); |
| 211 | |
David Howells | 45025bc | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 212 | /* We maintain an extra ref on the connection whilst it is on |
| 213 | * the rxrpc_connections list. |
| 214 | */ |
| 215 | atomic_set(&conn->usage, 2); |
| 216 | |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 217 | write_lock(&rxrpc_connection_lock); |
| 218 | list_add_tail(&conn->link, &rxrpc_connections); |
David Howells | 4d028b2 | 2016-08-24 07:30:52 +0100 | [diff] [blame] | 219 | list_add_tail(&conn->proc_link, &rxrpc_connection_proc_list); |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 220 | write_unlock(&rxrpc_connection_lock); |
| 221 | |
David Howells | 8496af5 | 2016-07-01 07:51:50 +0100 | [diff] [blame] | 222 | /* Make the connection a target for incoming packets. */ |
| 223 | rxrpc_publish_service_conn(peer, conn); |
| 224 | |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 225 | new = "new"; |
| 226 | |
| 227 | success: |
| 228 | _net("CONNECTION %s %d {%x}", new, conn->debug_id, conn->proto.cid); |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 229 | _leave(" = %p {u=%d}", conn, atomic_read(&conn->usage)); |
| 230 | return conn; |
| 231 | |
David Howells | 8496af5 | 2016-07-01 07:51:50 +0100 | [diff] [blame] | 232 | found_extant_connection_rcu: |
| 233 | rcu_read_unlock(); |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 234 | goto success; |
| 235 | |
David Howells | 8496af5 | 2016-07-01 07:51:50 +0100 | [diff] [blame] | 236 | security_mismatch_rcu: |
| 237 | rcu_read_unlock(); |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 238 | _leave(" = -EKEYREJECTED"); |
| 239 | return ERR_PTR(-EKEYREJECTED); |
David Howells | 8496af5 | 2016-07-01 07:51:50 +0100 | [diff] [blame] | 240 | |
| 241 | enomem_peer: |
| 242 | rxrpc_put_peer(peer); |
| 243 | enomem: |
| 244 | _leave(" = -ENOMEM"); |
| 245 | return ERR_PTR(-ENOMEM); |
David Howells | 7877a4a | 2016-04-04 14:00:40 +0100 | [diff] [blame] | 246 | } |
David Howells | 001c112 | 2016-06-30 10:45:22 +0100 | [diff] [blame] | 247 | |
| 248 | /* |
| 249 | * Remove the service connection from the peer's tree, thereby removing it as a |
| 250 | * target for incoming packets. |
| 251 | */ |
| 252 | void rxrpc_unpublish_service_conn(struct rxrpc_connection *conn) |
| 253 | { |
| 254 | struct rxrpc_peer *peer = conn->params.peer; |
| 255 | |
David Howells | 8496af5 | 2016-07-01 07:51:50 +0100 | [diff] [blame] | 256 | write_seqlock_bh(&peer->service_conn_lock); |
David Howells | 001c112 | 2016-06-30 10:45:22 +0100 | [diff] [blame] | 257 | if (test_and_clear_bit(RXRPC_CONN_IN_SERVICE_CONNS, &conn->flags)) |
| 258 | rb_erase(&conn->service_node, &peer->service_conns); |
David Howells | 8496af5 | 2016-07-01 07:51:50 +0100 | [diff] [blame] | 259 | write_sequnlock_bh(&peer->service_conn_lock); |
David Howells | 001c112 | 2016-06-30 10:45:22 +0100 | [diff] [blame] | 260 | } |