diff options
Diffstat (limited to 'net/sctp/input.c')
| -rw-r--r-- | net/sctp/input.c | 913 |
1 files changed, 913 insertions, 0 deletions
diff --git a/net/sctp/input.c b/net/sctp/input.c new file mode 100644 index 0000000..b719a77 --- /dev/null +++ b/net/sctp/input.c @@ -0,0 +1,913 @@ +/* SCTP kernel reference 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 reference Implementation + * + * These functions handle all input from the IP layer into SCTP. + * + * The SCTP reference 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. + * + * The SCTP reference 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> + +/* 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); + + +/* Calculate the SCTP checksum of an SCTP packet. */ +static inline int sctp_rcv_checksum(struct sk_buff *skb) +{ + struct sctphdr *sh; + __u32 cmp, val; + struct sk_buff *list = skb_shinfo(skb)->frag_list; + + sh = (struct sctphdr *) skb->h.raw; + cmp = ntohl(sh->checksum); + + 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; +} + +/* The free routine for skbuffs that sctp receives */ +static void sctp_rfree(struct sk_buff *skb) +{ + atomic_sub(sizeof(struct sctp_chunk),&skb->sk->sk_rmem_alloc); + sock_rfree(skb); +} + +/* The ownership wrapper routine to do receive buffer accounting */ +static void sctp_rcv_set_owner_r(struct sk_buff *skb, struct sock *sk) +{ + skb_set_owner_r(skb,sk); + skb->destructor = sctp_rfree; + atomic_add(sizeof(struct sctp_chunk),&sk->sk_rmem_alloc); +} + +/* + * 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; + int ret = 0; + + if (skb->pkt_type!=PACKET_HOST) + goto discard_it; + + SCTP_INC_STATS_BH(SCTP_MIB_INSCTPPACKS); + + sh = (struct sctphdr *) skb->h.raw; + + /* Pull up the IP and SCTP headers. */ + __skb_pull(skb, skb->h.raw - skb->data); + if (skb->len < sizeof(struct sctphdr)) + goto discard_it; + if (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(skb->nh.iph->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) || !af->addr_valid(&dest, NULL)) + goto discard_it; + + asoc = __sctp_rcv_lookup(skb, &src, &dest, &transport); + + /* + * 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) { + ep = __sctp_rcv_lookup_endpoint(&dest); + if (sctp_rcv_ootb(skb)) { + SCTP_INC_STATS_BH(SCTP_MIB_OUTOFBLUES); + goto discard_release; + } + } + + /* Retrieve the common input handling substructure. */ + rcvr = asoc ? &asoc->base : &ep->base; + sk = rcvr->sk; + + if ((sk) && (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)) { + goto discard_release; + } + + + /* SCTP seems to always need a timestamp right now (FIXME) */ + if (skb->stamp.tv_sec == 0) { + do_gettimeofday(&skb->stamp); + sock_enable_timestamp(sk); + } + + if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family)) + goto discard_release; + + ret = sk_filter(sk, skb, 1); + if (ret) + goto discard_release; + + /* Create an SCTP packet structure. */ + chunk = sctp_chunkify(skb, asoc, sk); + if (!chunk) { + ret = -ENOMEM; + goto discard_release; + } + + sctp_rcv_set_owner_r(skb,sk); + + /* 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 (sock_owned_by_user(sk)) + sk_add_backlog(sk, (struct sk_buff *) chunk); + else + sctp_backlog_rcv(sk, (struct sk_buff *) chunk); + + /* Release the sock and any reference counts we took in the + * lookup calls. + */ + sctp_bh_unlock_sock(sk); + if (asoc) + sctp_association_put(asoc); + else + sctp_endpoint_put(ep); + sock_put(sk); + return ret; + +discard_it: + kfree_skb(skb); + return ret; + +discard_release: + /* Release any structures we may be holding. */ + if (asoc) { + sock_put(asoc->base.sk); + sctp_association_put(asoc); + } else { + sock_put(ep->base.sk); + sctp_endpoint_put(ep); + } + + goto discard_it; +} + +/* Handle second half of inbound skb processing. If the sock was busy, + * we may have need to delay processing until later when the sock is + * released (on the backlog). If not busy, we call this routine + * directly from the bottom half. + */ +int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) +{ + struct sctp_chunk *chunk; + struct sctp_inq *inqueue; + + /* One day chunk will live inside the skb, but for + * now this works. + */ + chunk = (struct sctp_chunk *) skb; + inqueue = &chunk->rcvr->inqueue; + + sctp_inq_push(inqueue, chunk); + return 0; +} + +/* Handle icmp frag needed error. */ +void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc, + struct sctp_transport *t, __u32 pmtu) +{ + if (unlikely(pmtu < SCTP_DEFAULT_MINSEGMENT)) { + printk(KERN_WARNING "%s: Reported pmtu %d too low, " + "using default minimum of %d\n", __FUNCTION__, pmtu, + SCTP_DEFAULT_MINSEGMENT); + pmtu = SCTP_DEFAULT_MINSEGMENT; + } + + if (!sock_owned_by_user(sk) && t && (t->pmtu != pmtu)) { + t->pmtu = pmtu; + sctp_assoc_sync_pmtu(asoc); + 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_endpoint *ep, + struct sctp_association *asoc, + struct sctp_transport *t) +{ + SCTP_DEBUG_PRINTK("%s\n", __FUNCTION__); + + sctp_do_sm(SCTP_EVENT_T_OTHER, + SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH), + asoc->state, asoc->ep, asoc, NULL, + 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_endpoint **epp, + 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_endpoint *ep = NULL; + struct sctp_association *asoc = NULL; + struct sctp_transport *transport = NULL; + + *app = NULL; *epp = 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) { + /* If there is no matching association, see if it matches any + * endpoint. This may happen for an ICMP error generated in + * response to an INIT_ACK. + */ + ep = __sctp_rcv_lookup_endpoint(&daddr); + if (!ep) { + return NULL; + } + } + + if (asoc) { + sk = asoc->base.sk; + + if (ntohl(sctphdr->vtag) != asoc->c.peer_vtag) { + ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); + goto out; + } + } else + sk = ep->base.sk; + + 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(LINUX_MIB_LOCKDROPPEDICMPS); + + *epp = ep; + *app = asoc; + *tpp = transport; + return sk; + +out: + sock_put(sk); + if (asoc) + sctp_association_put(asoc); + if (ep) + sctp_endpoint_put(ep); + return NULL; +} + +/* Common cleanup code for icmp/icmpv6 error handler. */ +void sctp_err_finish(struct sock *sk, struct sctp_endpoint *ep, + struct sctp_association *asoc) +{ + sctp_bh_unlock_sock(sk); + sock_put(sk); + if (asoc) + sctp_association_put(asoc); + if (ep) + sctp_endpoint_put(ep); +} + +/* + * 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; + struct sctphdr *sh = (struct sctphdr *)(skb->data + (iph->ihl <<2)); + int type = skb->h.icmph->type; + int code = skb->h.icmph->code; + struct sock *sk; + struct sctp_endpoint *ep; + struct sctp_association *asoc; + struct sctp_transport *transport; + struct inet_sock *inet; + char *saveip, *savesctp; + int err; + + if (skb->len < ((iph->ihl << 2) + 8)) { + ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); + return; + } + + /* Fix up skb to look at the embedded net header. */ + saveip = skb->nh.raw; + savesctp = skb->h.raw; + skb->nh.iph = iph; + skb->h.raw = (char *)sh; + sk = sctp_err_lookup(AF_INET, skb, sh, &ep, &asoc, &transport); + /* Put back, the original pointers. */ + skb->nh.raw = saveip; + skb->h.raw = savesctp; + if (!sk) { + ICMP_INC_STATS_BH(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, ep, 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, ep, 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. + */ +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; + ch_end = ((__u8 *) ch) + WORD_ROUND(ntohs(ch->length)); + + /* Scan through all the chunks in the packet. */ + while (ch_end > (__u8 *)ch && ch_end < skb->tail) { + + /* 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 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; + ch_end = ((__u8 *) ch) + WORD_ROUND(ntohs(ch->length)); + } + + return 0; + +discard: + return 1; +} + +/* Insert endpoint into the hash table. */ +static void __sctp_hash_endpoint(struct sctp_endpoint *ep) +{ + struct sctp_ep_common **epp; + 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); + epp = &head->chain; + epb->next = *epp; + if (epb->next) + (*epp)->pprev = &epb->next; + *epp = epb; + epb->pprev = epp; + 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; + + epb->hashent = sctp_ep_hashfn(epb->bind_addr.port); + + head = &sctp_ep_hashtable[epb->hashent]; + + sctp_write_lock(&head->lock); + + if (epb->pprev) { + if (epb->next) + epb->next->pprev = epb->pprev; + *epb->pprev = epb->next; + epb->pprev = NULL; + } + + 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; + int hash; + + hash = sctp_ep_hashfn(laddr->v4.sin_port); + head = &sctp_ep_hashtable[hash]; + read_lock(&head->lock); + for (epb = head->chain; epb; epb = epb->next) { + ep = sctp_ep(epb); + if (sctp_endpoint_is_match(ep, laddr)) + goto hit; + } + + ep = sctp_sk((sctp_get_ctl_sock()))->ep; + epb = &ep->base; + +hit: + sctp_endpoint_hold(ep); + sock_hold(epb->sk); + 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 **epp; + 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); + epp = &head->chain; + epb->next = *epp; + if (epb->next) + (*epp)->pprev = &epb->next; + *epp = epb; + epb->pprev = epp; + sctp_write_unlock(&head->lock); +} + +/* Add an association to the hash. Local BH-safe. */ +void sctp_hash_established(struct sctp_association *asoc) +{ + 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); + + if (epb->pprev) { + if (epb->next) + epb->next->pprev = epb->pprev; + *epb->pprev = epb->next; + epb->pprev = NULL; + } + + sctp_write_unlock(&head->lock); +} + +/* Remove association from the hash table. Local BH-safe. */ +void sctp_unhash_established(struct sctp_association *asoc) +{ + 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; + int hash; + + /* Optimize here for direct hit, only listening connections can + * have wildcards anyways. + */ + hash = sctp_assoc_hashfn(local->v4.sin_port, peer->v4.sin_port); + head = &sctp_assoc_hashtable[hash]; + read_lock(&head->lock); + for (epb = head->chain; epb; epb = epb->next) { + 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); + sock_hold(epb->sk); + 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))) { + sock_put(asoc->base.sk); + 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 = (struct sctphdr *) skb->h.raw; + 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; + + /* If this is INIT/INIT-ACK look inside the chunk too. */ + switch (ch->type) { + case SCTP_CID_INIT: + case SCTP_CID_INIT_ACK: + break; + default: + return NULL; + } + + /* 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; + + /* + * 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, ntohs(sh->source), 0); + + asoc = __sctp_lookup_association(laddr, paddr, &transport); + if (asoc) + return asoc; + } + + 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_init_lookup(skb, laddr, transportp); + + return asoc; +} |