diff options
Diffstat (limited to 'net/sctp/input.c')
| -rw-r--r-- | net/sctp/input.c | 1128 |
1 files changed, 1128 insertions, 0 deletions
diff --git a/net/sctp/input.c b/net/sctp/input.c new file mode 100644 index 0000000..2e4a864 --- /dev/null +++ b/net/sctp/input.c @@ -0,0 +1,1128 @@ +/* SCTP kernel implementation + * Copyright (c) 1999-2000 Cisco, Inc. + * Copyright (c) 1999-2001 Motorola, Inc. + * Copyright (c) 2001-2003 International Business Machines, Corp. + * Copyright (c) 2001 Intel Corp. + * Copyright (c) 2001 Nokia, Inc. + * Copyright (c) 2001 La Monte H.P. Yarroll + * + * This file is part of the SCTP kernel implementation + * + * These functions handle all input from the IP layer into SCTP. + * + * This SCTP implementation 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, or (at your option) + * any later version. + * + * This SCTP implementation is distributed in the hope that it + * will be useful, but WITHOUT ANY WARRANTY; without even the implied + * ************************ + * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. + * See the GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with GNU CC; see the file COPYING. If not, write to + * the Free Software Foundation, 59 Temple Place - Suite 330, + * Boston, MA 02111-1307, USA. + * + * Please send any bug reports or fixes you make to the + * email address(es): + * lksctp developers <lksctp-developers@lists.sourceforge.net> + * + * Or submit a bug report through the following website: + * http://www.sf.net/projects/lksctp + * + * Written or modified by: + * La Monte H.P. Yarroll <piggy@acm.org> + * Karl Knutson <karl@athena.chicago.il.us> + * Xingang Guo <xingang.guo@intel.com> + * Jon Grimm <jgrimm@us.ibm.com> + * Hui Huang <hui.huang@nokia.com> + * Daisy Chang <daisyc@us.ibm.com> + * Sridhar Samudrala <sri@us.ibm.com> + * Ardelle Fan <ardelle.fan@intel.com> + * + * Any bugs reported given to us we will try to fix... any fixes shared will + * be incorporated into the next SCTP release. + */ + +#include <linux/types.h> +#include <linux/list.h> /* For struct list_head */ +#include <linux/socket.h> +#include <linux/ip.h> +#include <linux/time.h> /* For struct timeval */ +#include <net/ip.h> +#include <net/icmp.h> +#include <net/snmp.h> +#include <net/sock.h> +#include <net/xfrm.h> +#include <net/sctp/sctp.h> +#include <net/sctp/sm.h> +#include <net/sctp/checksum.h> +#include <net/net_namespace.h> + +/* Forward declarations for internal helpers. */ +static int sctp_rcv_ootb(struct sk_buff *); +static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb, + const union sctp_addr *laddr, + const union sctp_addr *paddr, + struct sctp_transport **transportp); +static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr); +static struct sctp_association *__sctp_lookup_association( + const union sctp_addr *local, + const union sctp_addr *peer, + struct sctp_transport **pt); + +static void sctp_add_backlog(struct sock *sk, struct sk_buff *skb); + + +/* Calculate the SCTP checksum of an SCTP packet. */ +static inline int sctp_rcv_checksum(struct sk_buff *skb) +{ + struct sk_buff *list = skb_shinfo(skb)->frag_list; + struct sctphdr *sh = sctp_hdr(skb); + __be32 cmp = sh->checksum; + __be32 val = sctp_start_cksum((__u8 *)sh, skb_headlen(skb)); + + for (; list; list = list->next) + val = sctp_update_cksum((__u8 *)list->data, skb_headlen(list), + val); + + val = sctp_end_cksum(val); + + if (val != cmp) { + /* CRC failure, dump it. */ + SCTP_INC_STATS_BH(SCTP_MIB_CHECKSUMERRORS); + return -1; + } + return 0; +} + +struct sctp_input_cb { + union { + struct inet_skb_parm h4; +#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE) + struct inet6_skb_parm h6; +#endif + } header; + struct sctp_chunk *chunk; +}; +#define SCTP_INPUT_CB(__skb) ((struct sctp_input_cb *)&((__skb)->cb[0])) + +/* + * This is the routine which IP calls when receiving an SCTP packet. + */ +int sctp_rcv(struct sk_buff *skb) +{ + struct sock *sk; + struct sctp_association *asoc; + struct sctp_endpoint *ep = NULL; + struct sctp_ep_common *rcvr; + struct sctp_transport *transport = NULL; + struct sctp_chunk *chunk; + struct sctphdr *sh; + union sctp_addr src; + union sctp_addr dest; + int family; + struct sctp_af *af; + + if (skb->pkt_type!=PACKET_HOST) + goto discard_it; + + SCTP_INC_STATS_BH(SCTP_MIB_INSCTPPACKS); + + if (skb_linearize(skb)) + goto discard_it; + + sh = sctp_hdr(skb); + + /* Pull up the IP and SCTP headers. */ + __skb_pull(skb, skb_transport_offset(skb)); + if (skb->len < sizeof(struct sctphdr)) + goto discard_it; + if (!skb_csum_unnecessary(skb) && sctp_rcv_checksum(skb) < 0) + goto discard_it; + + skb_pull(skb, sizeof(struct sctphdr)); + + /* Make sure we at least have chunk headers worth of data left. */ + if (skb->len < sizeof(struct sctp_chunkhdr)) + goto discard_it; + + family = ipver2af(ip_hdr(skb)->version); + af = sctp_get_af_specific(family); + if (unlikely(!af)) + goto discard_it; + + /* Initialize local addresses for lookups. */ + af->from_skb(&src, skb, 1); + af->from_skb(&dest, skb, 0); + + /* If the packet is to or from a non-unicast address, + * silently discard the packet. + * + * This is not clearly defined in the RFC except in section + * 8.4 - OOTB handling. However, based on the book "Stream Control + * Transmission Protocol" 2.1, "It is important to note that the + * IP address of an SCTP transport address must be a routable + * unicast address. In other words, IP multicast addresses and + * IP broadcast addresses cannot be used in an SCTP transport + * address." + */ + if (!af->addr_valid(&src, NULL, skb) || + !af->addr_valid(&dest, NULL, skb)) + goto discard_it; + + asoc = __sctp_rcv_lookup(skb, &src, &dest, &transport); + + if (!asoc) + ep = __sctp_rcv_lookup_endpoint(&dest); + + /* Retrieve the common input handling substructure. */ + rcvr = asoc ? &asoc->base : &ep->base; + sk = rcvr->sk; + + /* + * If a frame arrives on an interface and the receiving socket is + * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB + */ + if (sk->sk_bound_dev_if && (sk->sk_bound_dev_if != af->skb_iif(skb))) + { + if (asoc) { + sctp_association_put(asoc); + asoc = NULL; + } else { + sctp_endpoint_put(ep); + ep = NULL; + } + sk = sctp_get_ctl_sock(); + ep = sctp_sk(sk)->ep; + sctp_endpoint_hold(ep); + rcvr = &ep->base; + } + + /* + * RFC 2960, 8.4 - Handle "Out of the blue" Packets. + * An SCTP packet is called an "out of the blue" (OOTB) + * packet if it is correctly formed, i.e., passed the + * receiver's checksum check, but the receiver is not + * able to identify the association to which this + * packet belongs. + */ + if (!asoc) { + if (sctp_rcv_ootb(skb)) { + SCTP_INC_STATS_BH(SCTP_MIB_OUTOFBLUES); + goto discard_release; + } + } + + if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family)) + goto discard_release; + nf_reset(skb); + + if (sk_filter(sk, skb)) + goto discard_release; + + /* Create an SCTP packet structure. */ + chunk = sctp_chunkify(skb, asoc, sk); + if (!chunk) + goto discard_release; + SCTP_INPUT_CB(skb)->chunk = chunk; + + /* Remember what endpoint is to handle this packet. */ + chunk->rcvr = rcvr; + + /* Remember the SCTP header. */ + chunk->sctp_hdr = sh; + + /* Set the source and destination addresses of the incoming chunk. */ + sctp_init_addrs(chunk, &src, &dest); + + /* Remember where we came from. */ + chunk->transport = transport; + + /* Acquire access to the sock lock. Note: We are safe from other + * bottom halves on this lock, but a user may be in the lock too, + * so check if it is busy. + */ + sctp_bh_lock_sock(sk); + + if (sk != rcvr->sk) { + /* Our cached sk is different from the rcvr->sk. This is + * because migrate()/accept() may have moved the association + * to a new socket and released all the sockets. So now we + * are holding a lock on the old socket while the user may + * be doing something with the new socket. Switch our veiw + * of the current sk. + */ + sctp_bh_unlock_sock(sk); + sk = rcvr->sk; + sctp_bh_lock_sock(sk); + } + + if (sock_owned_by_user(sk)) { + SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_BACKLOG); + sctp_add_backlog(sk, skb); + } else { + SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_SOFTIRQ); + sctp_inq_push(&chunk->rcvr->inqueue, chunk); + } + + sctp_bh_unlock_sock(sk); + + /* Release the asoc/ep ref we took in the lookup calls. */ + if (asoc) + sctp_association_put(asoc); + else + sctp_endpoint_put(ep); + + return 0; + +discard_it: + SCTP_INC_STATS_BH(SCTP_MIB_IN_PKT_DISCARDS); + kfree_skb(skb); + return 0; + +discard_release: + /* Release the asoc/ep ref we took in the lookup calls. */ + if (asoc) + sctp_association_put(asoc); + else + sctp_endpoint_put(ep); + + goto discard_it; +} + +/* Process the backlog queue of the socket. Every skb on + * the backlog holds a ref on an association or endpoint. + * We hold this ref throughout the state machine to make + * sure that the structure we need is still around. + */ +int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) +{ + struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; + struct sctp_inq *inqueue = &chunk->rcvr->inqueue; + struct sctp_ep_common *rcvr = NULL; + int backloged = 0; + + rcvr = chunk->rcvr; + + /* If the rcvr is dead then the association or endpoint + * has been deleted and we can safely drop the chunk + * and refs that we are holding. + */ + if (rcvr->dead) { + sctp_chunk_free(chunk); + goto done; + } + + if (unlikely(rcvr->sk != sk)) { + /* In this case, the association moved from one socket to + * another. We are currently sitting on the backlog of the + * old socket, so we need to move. + * However, since we are here in the process context we + * need to take make sure that the user doesn't own + * the new socket when we process the packet. + * If the new socket is user-owned, queue the chunk to the + * backlog of the new socket without dropping any refs. + * Otherwise, we can safely push the chunk on the inqueue. + */ + + sk = rcvr->sk; + sctp_bh_lock_sock(sk); + + if (sock_owned_by_user(sk)) { + sk_add_backlog(sk, skb); + backloged = 1; + } else + sctp_inq_push(inqueue, chunk); + + sctp_bh_unlock_sock(sk); + + /* If the chunk was backloged again, don't drop refs */ + if (backloged) + return 0; + } else { + sctp_inq_push(inqueue, chunk); + } + +done: + /* Release the refs we took in sctp_add_backlog */ + if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) + sctp_association_put(sctp_assoc(rcvr)); + else if (SCTP_EP_TYPE_SOCKET == rcvr->type) + sctp_endpoint_put(sctp_ep(rcvr)); + else + BUG(); + + return 0; +} + +static void sctp_add_backlog(struct sock *sk, struct sk_buff *skb) +{ + struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; + struct sctp_ep_common *rcvr = chunk->rcvr; + + /* Hold the assoc/ep while hanging on the backlog queue. + * This way, we know structures we need will not disappear from us + */ + if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type) + sctp_association_hold(sctp_assoc(rcvr)); + else if (SCTP_EP_TYPE_SOCKET == rcvr->type) + sctp_endpoint_hold(sctp_ep(rcvr)); + else + BUG(); + + sk_add_backlog(sk, skb); +} + +/* Handle icmp frag needed error. */ +void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc, + struct sctp_transport *t, __u32 pmtu) +{ + if (!t || (t->pathmtu <= pmtu)) + return; + + if (sock_owned_by_user(sk)) { + asoc->pmtu_pending = 1; + t->pmtu_pending = 1; + return; + } + + if (t->param_flags & SPP_PMTUD_ENABLE) { + /* Update transports view of the MTU */ + sctp_transport_update_pmtu(t, pmtu); + + /* Update association pmtu. */ + sctp_assoc_sync_pmtu(asoc); + } + + /* Retransmit with the new pmtu setting. + * Normally, if PMTU discovery is disabled, an ICMP Fragmentation + * Needed will never be sent, but if a message was sent before + * PMTU discovery was disabled that was larger than the PMTU, it + * would not be fragmented, so it must be re-transmitted fragmented. + */ + sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD); +} + +/* + * SCTP Implementer's Guide, 2.37 ICMP handling procedures + * + * ICMP8) If the ICMP code is a "Unrecognized next header type encountered" + * or a "Protocol Unreachable" treat this message as an abort + * with the T bit set. + * + * This function sends an event to the state machine, which will abort the + * association. + * + */ +void sctp_icmp_proto_unreachable(struct sock *sk, + struct sctp_association *asoc, + struct sctp_transport *t) +{ + SCTP_DEBUG_PRINTK("%s\n", __func__); + + sctp_do_sm(SCTP_EVENT_T_OTHER, + SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH), + asoc->state, asoc->ep, asoc, t, + GFP_ATOMIC); + +} + +/* Common lookup code for icmp/icmpv6 error handler. */ +struct sock *sctp_err_lookup(int family, struct sk_buff *skb, + struct sctphdr *sctphdr, + struct sctp_association **app, + struct sctp_transport **tpp) +{ + union sctp_addr saddr; + union sctp_addr daddr; + struct sctp_af *af; + struct sock *sk = NULL; + struct sctp_association *asoc; + struct sctp_transport *transport = NULL; + struct sctp_init_chunk *chunkhdr; + __u32 vtag = ntohl(sctphdr->vtag); + int len = skb->len - ((void *)sctphdr - (void *)skb->data); + + *app = NULL; *tpp = NULL; + + af = sctp_get_af_specific(family); + if (unlikely(!af)) { + return NULL; + } + + /* Initialize local addresses for lookups. */ + af->from_skb(&saddr, skb, 1); + af->from_skb(&daddr, skb, 0); + + /* Look for an association that matches the incoming ICMP error + * packet. + */ + asoc = __sctp_lookup_association(&saddr, &daddr, &transport); + if (!asoc) + return NULL; + + sk = asoc->base.sk; + + /* RFC 4960, Appendix C. ICMP Handling + * + * ICMP6) An implementation MUST validate that the Verification Tag + * contained in the ICMP message matches the Verification Tag of + * the peer. If the Verification Tag is not 0 and does NOT + * match, discard the ICMP message. If it is 0 and the ICMP + * message contains enough bytes to verify that the chunk type is + * an INIT chunk and that the Initiate Tag matches the tag of the + * peer, continue with ICMP7. If the ICMP message is too short + * or the chunk type or the Initiate Tag does not match, silently + * discard the packet. + */ + if (vtag == 0) { + chunkhdr = (struct sctp_init_chunk *)((void *)sctphdr + + sizeof(struct sctphdr)); + if (len < sizeof(struct sctphdr) + sizeof(sctp_chunkhdr_t) + + sizeof(__be32) || + chunkhdr->chunk_hdr.type != SCTP_CID_INIT || + ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag) { + goto out; + } + } else if (vtag != asoc->c.peer_vtag) { + goto out; + } + + sctp_bh_lock_sock(sk); + + /* If too many ICMPs get dropped on busy + * servers this needs to be solved differently. + */ + if (sock_owned_by_user(sk)) + NET_INC_STATS_BH(&init_net, LINUX_MIB_LOCKDROPPEDICMPS); + + *app = asoc; + *tpp = transport; + return sk; + +out: + if (asoc) + sctp_association_put(asoc); + return NULL; +} + +/* Common cleanup code for icmp/icmpv6 error handler. */ +void sctp_err_finish(struct sock *sk, struct sctp_association *asoc) +{ + sctp_bh_unlock_sock(sk); + if (asoc) + sctp_association_put(asoc); +} + +/* + * This routine is called by the ICMP module when it gets some + * sort of error condition. If err < 0 then the socket should + * be closed and the error returned to the user. If err > 0 + * it's just the icmp type << 8 | icmp code. After adjustment + * header points to the first 8 bytes of the sctp header. We need + * to find the appropriate port. + * + * The locking strategy used here is very "optimistic". When + * someone else accesses the socket the ICMP is just dropped + * and for some paths there is no check at all. + * A more general error queue to queue errors for later handling + * is probably better. + * + */ +void sctp_v4_err(struct sk_buff *skb, __u32 info) +{ + struct iphdr *iph = (struct iphdr *)skb->data; + const int ihlen = iph->ihl * 4; + const int type = icmp_hdr(skb)->type; + const int code = icmp_hdr(skb)->code; + struct sock *sk; + struct sctp_association *asoc = NULL; + struct sctp_transport *transport; + struct inet_sock *inet; + sk_buff_data_t saveip, savesctp; + int err; + + if (skb->len < ihlen + 8) { + ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS); + return; + } + + /* Fix up skb to look at the embedded net header. */ + saveip = skb->network_header; + savesctp = skb->transport_header; + skb_reset_network_header(skb); + skb_set_transport_header(skb, ihlen); + sk = sctp_err_lookup(AF_INET, skb, sctp_hdr(skb), &asoc, &transport); + /* Put back, the original values. */ + skb->network_header = saveip; + skb->transport_header = savesctp; + if (!sk) { + ICMP_INC_STATS_BH(&init_net, ICMP_MIB_INERRORS); + return; + } + /* Warning: The sock lock is held. Remember to call + * sctp_err_finish! + */ + + switch (type) { + case ICMP_PARAMETERPROB: + err = EPROTO; + break; + case ICMP_DEST_UNREACH: + if (code > NR_ICMP_UNREACH) + goto out_unlock; + + /* PMTU discovery (RFC1191) */ + if (ICMP_FRAG_NEEDED == code) { + sctp_icmp_frag_needed(sk, asoc, transport, info); + goto out_unlock; + } + else { + if (ICMP_PROT_UNREACH == code) { + sctp_icmp_proto_unreachable(sk, asoc, + transport); + goto out_unlock; + } + } + err = icmp_err_convert[code].errno; + break; + case ICMP_TIME_EXCEEDED: + /* Ignore any time exceeded errors due to fragment reassembly + * timeouts. + */ + if (ICMP_EXC_FRAGTIME == code) + goto out_unlock; + + err = EHOSTUNREACH; + break; + default: + goto out_unlock; + } + + inet = inet_sk(sk); + if (!sock_owned_by_user(sk) && inet->recverr) { + sk->sk_err = err; + sk->sk_error_report(sk); + } else { /* Only an error on timeout */ + sk->sk_err_soft = err; + } + +out_unlock: + sctp_err_finish(sk, asoc); +} + +/* + * RFC 2960, 8.4 - Handle "Out of the blue" Packets. + * + * This function scans all the chunks in the OOTB packet to determine if + * the packet should be discarded right away. If a response might be needed + * for this packet, or, if further processing is possible, the packet will + * be queued to a proper inqueue for the next phase of handling. + * + * Output: + * Return 0 - If further processing is needed. + * Return 1 - If the packet can be discarded right away. + */ +static int sctp_rcv_ootb(struct sk_buff *skb) +{ + sctp_chunkhdr_t *ch; + __u8 *ch_end; + sctp_errhdr_t *err; + + ch = (sctp_chunkhdr_t *) skb->data; + + /* Scan through all the chunks in the packet. */ + do { + /* Break out if chunk length is less then minimal. */ + if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t)) + break; + + ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length)); + if (ch_end > skb_tail_pointer(skb)) + break; + + /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the + * receiver MUST silently discard the OOTB packet and take no + * further action. + */ + if (SCTP_CID_ABORT == ch->type) + goto discard; + + /* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE + * chunk, the receiver should silently discard the packet + * and take no further action. + */ + if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type) + goto discard; + + /* RFC 4460, 2.11.2 + * This will discard packets with INIT chunk bundled as + * subsequent chunks in the packet. When INIT is first, + * the normal INIT processing will discard the chunk. + */ + if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data) + goto discard; + + /* RFC 8.4, 7) If the packet contains a "Stale cookie" ERROR + * or a COOKIE ACK the SCTP Packet should be silently + * discarded. + */ + if (SCTP_CID_COOKIE_ACK == ch->type) + goto discard; + + if (SCTP_CID_ERROR == ch->type) { + sctp_walk_errors(err, ch) { + if (SCTP_ERROR_STALE_COOKIE == err->cause) + goto discard; + } + } + + ch = (sctp_chunkhdr_t *) ch_end; + } while (ch_end < skb_tail_pointer(skb)); + + return 0; + +discard: + return 1; +} + +/* Insert endpoint into the hash table. */ +static void __sctp_hash_endpoint(struct sctp_endpoint *ep) +{ + struct sctp_ep_common *epb; + struct sctp_hashbucket *head; + + epb = &ep->base; + + epb->hashent = sctp_ep_hashfn(epb->bind_addr.port); + head = &sctp_ep_hashtable[epb->hashent]; + + sctp_write_lock(&head->lock); + hlist_add_head(&epb->node, &head->chain); + sctp_write_unlock(&head->lock); +} + +/* Add an endpoint to the hash. Local BH-safe. */ +void sctp_hash_endpoint(struct sctp_endpoint *ep) +{ + sctp_local_bh_disable(); + __sctp_hash_endpoint(ep); + sctp_local_bh_enable(); +} + +/* Remove endpoint from the hash table. */ +static void __sctp_unhash_endpoint(struct sctp_endpoint *ep) +{ + struct sctp_hashbucket *head; + struct sctp_ep_common *epb; + + epb = &ep->base; + + if (hlist_unhashed(&epb->node)) + return; + + epb->hashent = sctp_ep_hashfn(epb->bind_addr.port); + + head = &sctp_ep_hashtable[epb->hashent]; + + sctp_write_lock(&head->lock); + __hlist_del(&epb->node); + sctp_write_unlock(&head->lock); +} + +/* Remove endpoint from the hash. Local BH-safe. */ +void sctp_unhash_endpoint(struct sctp_endpoint *ep) +{ + sctp_local_bh_disable(); + __sctp_unhash_endpoint(ep); + sctp_local_bh_enable(); +} + +/* Look up an endpoint. */ +static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr) +{ + struct sctp_hashbucket *head; + struct sctp_ep_common *epb; + struct sctp_endpoint *ep; + struct hlist_node *node; + int hash; + + hash = sctp_ep_hashfn(ntohs(laddr->v4.sin_port)); + head = &sctp_ep_hashtable[hash]; + read_lock(&head->lock); + sctp_for_each_hentry(epb, node, &head->chain) { + ep = sctp_ep(epb); + if (sctp_endpoint_is_match(ep, laddr)) + goto hit; + } + + ep = sctp_sk((sctp_get_ctl_sock()))->ep; + +hit: + sctp_endpoint_hold(ep); + read_unlock(&head->lock); + return ep; +} + +/* Insert association into the hash table. */ +static void __sctp_hash_established(struct sctp_association *asoc) +{ + struct sctp_ep_common *epb; + struct sctp_hashbucket *head; + + epb = &asoc->base; + + /* Calculate which chain this entry will belong to. */ + epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, asoc->peer.port); + + head = &sctp_assoc_hashtable[epb->hashent]; + + sctp_write_lock(&head->lock); + hlist_add_head(&epb->node, &head->chain); + sctp_write_unlock(&head->lock); +} + +/* Add an association to the hash. Local BH-safe. */ +void sctp_hash_established(struct sctp_association *asoc) +{ + if (asoc->temp) + return; + + sctp_local_bh_disable(); + __sctp_hash_established(asoc); + sctp_local_bh_enable(); +} + +/* Remove association from the hash table. */ +static void __sctp_unhash_established(struct sctp_association *asoc) +{ + struct sctp_hashbucket *head; + struct sctp_ep_common *epb; + + epb = &asoc->base; + + epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port, + asoc->peer.port); + + head = &sctp_assoc_hashtable[epb->hashent]; + + sctp_write_lock(&head->lock); + __hlist_del(&epb->node); + sctp_write_unlock(&head->lock); +} + +/* Remove association from the hash table. Local BH-safe. */ +void sctp_unhash_established(struct sctp_association *asoc) +{ + if (asoc->temp) + return; + + sctp_local_bh_disable(); + __sctp_unhash_established(asoc); + sctp_local_bh_enable(); +} + +/* Look up an association. */ +static struct sctp_association *__sctp_lookup_association( + const union sctp_addr *local, + const union sctp_addr *peer, + struct sctp_transport **pt) +{ + struct sctp_hashbucket *head; + struct sctp_ep_common *epb; + struct sctp_association *asoc; + struct sctp_transport *transport; + struct hlist_node *node; + int hash; + + /* Optimize here for direct hit, only listening connections can + * have wildcards anyways. + */ + hash = sctp_assoc_hashfn(ntohs(local->v4.sin_port), ntohs(peer->v4.sin_port)); + head = &sctp_assoc_hashtable[hash]; + read_lock(&head->lock); + sctp_for_each_hentry(epb, node, &head->chain) { + asoc = sctp_assoc(epb); + transport = sctp_assoc_is_match(asoc, local, peer); + if (transport) + goto hit; + } + + read_unlock(&head->lock); + + return NULL; + +hit: + *pt = transport; + sctp_association_hold(asoc); + read_unlock(&head->lock); + return asoc; +} + +/* Look up an association. BH-safe. */ +SCTP_STATIC +struct sctp_association *sctp_lookup_association(const union sctp_addr *laddr, + const union sctp_addr *paddr, + struct sctp_transport **transportp) +{ + struct sctp_association *asoc; + + sctp_local_bh_disable(); + asoc = __sctp_lookup_association(laddr, paddr, transportp); + sctp_local_bh_enable(); + + return asoc; +} + +/* Is there an association matching the given local and peer addresses? */ +int sctp_has_association(const union sctp_addr *laddr, + const union sctp_addr *paddr) +{ + struct sctp_association *asoc; + struct sctp_transport *transport; + + if ((asoc = sctp_lookup_association(laddr, paddr, &transport))) { + sctp_association_put(asoc); + return 1; + } + + return 0; +} + +/* + * SCTP Implementors Guide, 2.18 Handling of address + * parameters within the INIT or INIT-ACK. + * + * D) When searching for a matching TCB upon reception of an INIT + * or INIT-ACK chunk the receiver SHOULD use not only the + * source address of the packet (containing the INIT or + * INIT-ACK) but the receiver SHOULD also use all valid + * address parameters contained within the chunk. + * + * 2.18.3 Solution description + * + * This new text clearly specifies to an implementor the need + * to look within the INIT or INIT-ACK. Any implementation that + * does not do this, may not be able to establish associations + * in certain circumstances. + * + */ +static struct sctp_association *__sctp_rcv_init_lookup(struct sk_buff *skb, + const union sctp_addr *laddr, struct sctp_transport **transportp) +{ + struct sctp_association *asoc; + union sctp_addr addr; + union sctp_addr *paddr = &addr; + struct sctphdr *sh = sctp_hdr(skb); + sctp_chunkhdr_t *ch; + union sctp_params params; + sctp_init_chunk_t *init; + struct sctp_transport *transport; + struct sctp_af *af; + + ch = (sctp_chunkhdr_t *) skb->data; + + /* + * This code will NOT touch anything inside the chunk--it is + * strictly READ-ONLY. + * + * RFC 2960 3 SCTP packet Format + * + * Multiple chunks can be bundled into one SCTP packet up to + * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN + * COMPLETE chunks. These chunks MUST NOT be bundled with any + * other chunk in a packet. See Section 6.10 for more details + * on chunk bundling. + */ + + /* Find the start of the TLVs and the end of the chunk. This is + * the region we search for address parameters. + */ + init = (sctp_init_chunk_t *)skb->data; + + /* Walk the parameters looking for embedded addresses. */ + sctp_walk_params(params, init, init_hdr.params) { + + /* Note: Ignoring hostname addresses. */ + af = sctp_get_af_specific(param_type2af(params.p->type)); + if (!af) + continue; + + af->from_addr_param(paddr, params.addr, sh->source, 0); + + asoc = __sctp_lookup_association(laddr, paddr, &transport); + if (asoc) + return asoc; + } + + return NULL; +} + +/* ADD-IP, Section 5.2 + * When an endpoint receives an ASCONF Chunk from the remote peer + * special procedures may be needed to identify the association the + * ASCONF Chunk is associated with. To properly find the association + * the following procedures SHOULD be followed: + * + * D2) If the association is not found, use the address found in the + * Address Parameter TLV combined with the port number found in the + * SCTP common header. If found proceed to rule D4. + * + * D2-ext) If more than one ASCONF Chunks are packed together, use the + * address found in the ASCONF Address Parameter TLV of each of the + * subsequent ASCONF Chunks. If found, proceed to rule D4. + */ +static struct sctp_association *__sctp_rcv_asconf_lookup( + sctp_chunkhdr_t *ch, + const union sctp_addr *laddr, + __be16 peer_port, + struct sctp_transport **transportp) +{ + sctp_addip_chunk_t *asconf = (struct sctp_addip_chunk *)ch; + struct sctp_af *af; + union sctp_addr_param *param; + union sctp_addr paddr; + + /* Skip over the ADDIP header and find the Address parameter */ + param = (union sctp_addr_param *)(asconf + 1); + + af = sctp_get_af_specific(param_type2af(param->v4.param_hdr.type)); + if (unlikely(!af)) + return NULL; + + af->from_addr_param(&paddr, param, peer_port, 0); + + return __sctp_lookup_association(laddr, &paddr, transportp); +} + + +/* SCTP-AUTH, Section 6.3: +* If the receiver does not find a STCB for a packet containing an AUTH +* chunk as the first chunk and not a COOKIE-ECHO chunk as the second +* chunk, it MUST use the chunks after the AUTH chunk to look up an existing +* association. +* +* This means that any chunks that can help us identify the association need +* to be looked at to find this assocation. +*/ +static struct sctp_association *__sctp_rcv_walk_lookup(struct sk_buff *skb, + const union sctp_addr *laddr, + struct sctp_transport **transportp) +{ + struct sctp_association *asoc = NULL; + sctp_chunkhdr_t *ch; + int have_auth = 0; + unsigned int chunk_num = 1; + __u8 *ch_end; + + /* Walk through the chunks looking for AUTH or ASCONF chunks + * to help us find the association. + */ + ch = (sctp_chunkhdr_t *) skb->data; + do { + /* Break out if chunk length is less then minimal. */ + if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t)) + break; + + ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length)); + if (ch_end > skb_tail_pointer(skb)) + break; + + switch(ch->type) { + case SCTP_CID_AUTH: + have_auth = chunk_num; + break; + + case SCTP_CID_COOKIE_ECHO: + /* If a packet arrives containing an AUTH chunk as + * a first chunk, a COOKIE-ECHO chunk as the second + * chunk, and possibly more chunks after them, and + * the receiver does not have an STCB for that + * packet, then authentication is based on + * the contents of the COOKIE- ECHO chunk. + */ + if (have_auth == 1 && chunk_num == 2) + return NULL; + break; + + case SCTP_CID_ASCONF: + if (have_auth || sctp_addip_noauth) + asoc = __sctp_rcv_asconf_lookup(ch, laddr, + sctp_hdr(skb)->source, + transportp); + default: + break; + } + + if (asoc) + break; + + ch = (sctp_chunkhdr_t *) ch_end; + chunk_num++; + } while (ch_end < skb_tail_pointer(skb)); + + return asoc; +} + +/* + * There are circumstances when we need to look inside the SCTP packet + * for information to help us find the association. Examples + * include looking inside of INIT/INIT-ACK chunks or after the AUTH + * chunks. + */ +static struct sctp_association *__sctp_rcv_lookup_harder(struct sk_buff *skb, + const union sctp_addr *laddr, + struct sctp_transport **transportp) +{ + sctp_chunkhdr_t *ch; + + ch = (sctp_chunkhdr_t *) skb->data; + + /* The code below will attempt to walk the chunk and extract + * parameter information. Before we do that, we need to verify + * that the chunk length doesn't cause overflow. Otherwise, we'll + * walk off the end. + */ + if (WORD_ROUND(ntohs(ch->length)) > skb->len) + return NULL; + + /* If this is INIT/INIT-ACK look inside the chunk too. */ + switch (ch->type) { + case SCTP_CID_INIT: + case SCTP_CID_INIT_ACK: + return __sctp_rcv_init_lookup(skb, laddr, transportp); + break; + + default: + return __sctp_rcv_walk_lookup(skb, laddr, transportp); + break; + } + + + return NULL; +} + +/* Lookup an association for an inbound skb. */ +static struct sctp_association *__sctp_rcv_lookup(struct sk_buff *skb, + const union sctp_addr *paddr, + const union sctp_addr *laddr, + struct sctp_transport **transportp) +{ + struct sctp_association *asoc; + + asoc = __sctp_lookup_association(laddr, paddr, transportp); + + /* Further lookup for INIT/INIT-ACK packets. + * SCTP Implementors Guide, 2.18 Handling of address + * parameters within the INIT or INIT-ACK. + */ + if (!asoc) + asoc = __sctp_rcv_lookup_harder(skb, laddr, transportp); + + return asoc; +} |
