/* 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, see * . * * Please send any bug reports or fixes you make to the * email address(es): * lksctp developers * * Written or modified by: * La Monte H.P. Yarroll * Karl Knutson * Xingang Guo * Jon Grimm * Hui Huang * Daisy Chang * Sridhar Samudrala * Ardelle Fan */ #include #include /* For struct list_head */ #include #include #include /* For struct timeval */ #include #include #include #include #include #include #include #include #include #include /* Forward declarations for internal helpers. */ static int sctp_rcv_ootb(struct sk_buff *); static struct sctp_association *__sctp_rcv_lookup(struct net *net, struct sk_buff *skb, const union sctp_addr *paddr, const union sctp_addr *laddr, struct sctp_transport **transportp); static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net, const union sctp_addr *laddr); static struct sctp_association *__sctp_lookup_association( struct net *net, const union sctp_addr *local, const union sctp_addr *peer, struct sctp_transport **pt); static int 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 net *net, struct sk_buff *skb) { struct sctphdr *sh = sctp_hdr(skb); __le32 cmp = sh->checksum; __le32 val = sctp_compute_cksum(skb, 0); if (val != cmp) { /* CRC failure, dump it. */ __SCTP_INC_STATS(net, SCTP_MIB_CHECKSUMERRORS); return -1; } return 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; union sctp_addr src; union sctp_addr dest; int family; struct sctp_af *af; struct net *net = dev_net(skb->dev); if (skb->pkt_type != PACKET_HOST) goto discard_it; __SCTP_INC_STATS(net, SCTP_MIB_INSCTPPACKS); /* If packet is too small to contain a single chunk, let's not * waste time on it anymore. */ if (skb->len < sizeof(struct sctphdr) + sizeof(struct sctp_chunkhdr) + skb_transport_offset(skb)) goto discard_it; /* If the packet is fragmented and we need to do crc checking, * it's better to just linearize it otherwise crc computing * takes longer. */ if ((!(skb_shinfo(skb)->gso_type & SKB_GSO_SCTP) && skb_linearize(skb)) || !pskb_may_pull(skb, sizeof(struct sctphdr))) goto discard_it; /* Pull up the IP header. */ __skb_pull(skb, skb_transport_offset(skb)); skb->csum_valid = 0; /* Previous value not applicable */ if (skb_csum_unnecessary(skb)) __skb_decr_checksum_unnecessary(skb); else if (!sctp_checksum_disable && !(skb_shinfo(skb)->gso_type & SKB_GSO_SCTP) && sctp_rcv_checksum(net, skb) < 0) goto discard_it; skb->csum_valid = 1; __skb_pull(skb, sizeof(struct sctphdr)); family = ipver2af(ip_hdr(skb)->version); af = sctp_get_af_specific(family); if (unlikely(!af)) goto discard_it; SCTP_INPUT_CB(skb)->af = af; /* 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(net, skb, &src, &dest, &transport); if (!asoc) ep = __sctp_rcv_lookup_endpoint(net, &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 (transport) { sctp_transport_put(transport); asoc = NULL; transport = NULL; } else { sctp_endpoint_put(ep); ep = NULL; } sk = net->sctp.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(net, 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, GFP_ATOMIC); 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 = sctp_hdr(skb); /* 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. */ 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. */ bh_unlock_sock(sk); sk = rcvr->sk; bh_lock_sock(sk); } if (sock_owned_by_user(sk)) { if (sctp_add_backlog(sk, skb)) { bh_unlock_sock(sk); sctp_chunk_free(chunk); skb = NULL; /* sctp_chunk_free already freed the skb */ goto discard_release; } __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_BACKLOG); } else { __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_SOFTIRQ); sctp_inq_push(&chunk->rcvr->inqueue, chunk); } bh_unlock_sock(sk); /* Release the asoc/ep ref we took in the lookup calls. */ if (transport) sctp_transport_put(transport); else sctp_endpoint_put(ep); return 0; discard_it: __SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_DISCARDS); kfree_skb(skb); return 0; discard_release: /* Release the asoc/ep ref we took in the lookup calls. */ if (transport) sctp_transport_put(transport); 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_transport *t = chunk->transport; 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; local_bh_disable(); bh_lock_sock(sk); if (sock_owned_by_user(sk)) { if (sk_add_backlog(sk, skb, sk->sk_rcvbuf)) sctp_chunk_free(chunk); else backloged = 1; } else sctp_inq_push(inqueue, chunk); bh_unlock_sock(sk); local_bh_enable(); /* 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_transport_put(t); else if (SCTP_EP_TYPE_SOCKET == rcvr->type) sctp_endpoint_put(sctp_ep(rcvr)); else BUG(); return 0; } static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb) { struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk; struct sctp_transport *t = chunk->transport; struct sctp_ep_common *rcvr = chunk->rcvr; int ret; ret = sk_add_backlog(sk, skb, sk->sk_rcvbuf); if (!ret) { /* 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_transport_hold(t); else if (SCTP_EP_TYPE_SOCKET == rcvr->type) sctp_endpoint_hold(sctp_ep(rcvr)); else BUG(); } return ret; } /* 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); } void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t, struct sk_buff *skb) { struct dst_entry *dst; if (!t) return; dst = sctp_transport_dst_check(t); if (dst) dst->ops->redirect(dst, sk, skb); } /* * 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) { if (sock_owned_by_user(sk)) { if (timer_pending(&t->proto_unreach_timer)) return; else { if (!mod_timer(&t->proto_unreach_timer, jiffies + (HZ/20))) sctp_association_hold(asoc); } } else { struct net *net = sock_net(sk); pr_debug("%s: unrecognized next header type " "encountered!\n", __func__); if (del_timer(&t->proto_unreach_timer)) sctp_association_put(asoc); sctp_do_sm(net, 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(struct net *net, int family, struct sk_buff *skb, struct sctphdr *sctphdr, struct sctp_association **app, struct sctp_transport **tpp) { struct sctp_init_chunk *chunkhdr, _chunkhdr; 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; __u32 vtag = ntohl(sctphdr->vtag); *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(net, &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) { /* chunk header + first 4 octects of init header */ chunkhdr = skb_header_pointer(skb, skb_transport_offset(skb) + sizeof(struct sctphdr), sizeof(struct sctp_chunkhdr) + sizeof(__be32), &_chunkhdr); if (!chunkhdr || 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; } 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(net, LINUX_MIB_LOCKDROPPEDICMPS); *app = asoc; *tpp = transport; return sk; out: sctp_transport_put(transport); return NULL; } /* Common cleanup code for icmp/icmpv6 error handler. */ void sctp_err_finish(struct sock *sk, struct sctp_transport *t) { bh_unlock_sock(sk); sctp_transport_put(t); } /* * 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) { const struct iphdr *iph = (const 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; __u16 saveip, savesctp; int err; struct net *net = dev_net(skb->dev); /* 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(net, 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(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, SCTP_TRUNC4(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; case ICMP_REDIRECT: sctp_icmp_redirect(sk, transport, skb); /* Fall through to out_unlock. */ 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, transport); } /* * 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) { struct sctp_chunkhdr *ch, _ch; int ch_end, offset = 0; /* Scan through all the chunks in the packet. */ do { /* Make sure we have at least the header there */ if (offset + sizeof(_ch) > skb->len) break; ch = skb_header_pointer(skb, offset, sizeof(*ch), &_ch); /* Break out if chunk length is less then minimal. */ if (ntohs(ch->length) < sizeof(_ch)) break; ch_end = offset + SCTP_PAD4(ntohs(ch->length)); if (ch_end > skb->len) 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; offset = ch_end; } while (ch_end < skb->len); return 0; discard: return 1; } /* Insert endpoint into the hash table. */ static void __sctp_hash_endpoint(struct sctp_endpoint *ep) { struct net *net = sock_net(ep->base.sk); struct sctp_ep_common *epb; struct sctp_hashbucket *head; epb = &ep->base; epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port); head = &sctp_ep_hashtable[epb->hashent]; write_lock(&head->lock); hlist_add_head(&epb->node, &head->chain); write_unlock(&head->lock); } /* Add an endpoint to the hash. Local BH-safe. */ void sctp_hash_endpoint(struct sctp_endpoint *ep) { local_bh_disable(); __sctp_hash_endpoint(ep); local_bh_enable(); } /* Remove endpoint from the hash table. */ static void __sctp_unhash_endpoint(struct sctp_endpoint *ep) { struct net *net = sock_net(ep->base.sk); struct sctp_hashbucket *head; struct sctp_ep_common *epb; epb = &ep->base; epb->hashent = sctp_ep_hashfn(net, epb->bind_addr.port); head = &sctp_ep_hashtable[epb->hashent]; write_lock(&head->lock); hlist_del_init(&epb->node); write_unlock(&head->lock); } /* Remove endpoint from the hash. Local BH-safe. */ void sctp_unhash_endpoint(struct sctp_endpoint *ep) { local_bh_disable(); __sctp_unhash_endpoint(ep); local_bh_enable(); } /* Look up an endpoint. */ static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net, const union sctp_addr *laddr) { struct sctp_hashbucket *head; struct sctp_ep_common *epb; struct sctp_endpoint *ep; int hash; hash = sctp_ep_hashfn(net, ntohs(laddr->v4.sin_port)); head = &sctp_ep_hashtable[hash]; read_lock(&head->lock); sctp_for_each_hentry(epb, &head->chain) { ep = sctp_ep(epb); if (sctp_endpoint_is_match(ep, net, laddr)) goto hit; } ep = sctp_sk(net->sctp.ctl_sock)->ep; hit: sctp_endpoint_hold(ep); read_unlock(&head->lock); return ep; } /* rhashtable for transport */ struct sctp_hash_cmp_arg { const union sctp_addr *paddr; const struct net *net; u16 lport; }; static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg, const void *ptr) { struct sctp_transport *t = (struct sctp_transport *)ptr; const struct sctp_hash_cmp_arg *x = arg->key; int err = 1; if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr)) return err; if (!sctp_transport_hold(t)) return err; if (!net_eq(sock_net(t->asoc->base.sk), x->net)) goto out; if (x->lport != htons(t->asoc->base.bind_addr.port)) goto out; err = 0; out: sctp_transport_put(t); return err; } static inline u32 sctp_hash_obj(const void *data, u32 len, u32 seed) { const struct sctp_transport *t = data; const union sctp_addr *paddr = &t->ipaddr; const struct net *net = sock_net(t->asoc->base.sk); u16 lport = htons(t->asoc->base.bind_addr.port); u32 addr; if (paddr->sa.sa_family == AF_INET6) addr = jhash(&paddr->v6.sin6_addr, 16, seed); else addr = paddr->v4.sin_addr.s_addr; return jhash_3words(addr, ((__u32)paddr->v4.sin_port) << 16 | (__force __u32)lport, net_hash_mix(net), seed); } static inline u32 sctp_hash_key(const void *data, u32 len, u32 seed) { const struct sctp_hash_cmp_arg *x = data; const union sctp_addr *paddr = x->paddr; const struct net *net = x->net; u16 lport = x->lport; u32 addr; if (paddr->sa.sa_family == AF_INET6) addr = jhash(&paddr->v6.sin6_addr, 16, seed); else addr = paddr->v4.sin_addr.s_addr; return jhash_3words(addr, ((__u32)paddr->v4.sin_port) << 16 | (__force __u32)lport, net_hash_mix(net), seed); } static const struct rhashtable_params sctp_hash_params = { .head_offset = offsetof(struct sctp_transport, node), .hashfn = sctp_hash_key, .obj_hashfn = sctp_hash_obj, .obj_cmpfn = sctp_hash_cmp, .automatic_shrinking = true, }; int sctp_transport_hashtable_init(void) { return rhltable_init(&sctp_transport_hashtable, &sctp_hash_params); } void sctp_transport_hashtable_destroy(void) { rhltable_destroy(&sctp_transport_hashtable); } int sctp_hash_transport(struct sctp_transport *t) { struct sctp_transport *transport; struct rhlist_head *tmp, *list; struct sctp_hash_cmp_arg arg; int err; if (t->asoc->temp) return 0; arg.net = sock_net(t->asoc->base.sk); arg.paddr = &t->ipaddr; arg.lport = htons(t->asoc->base.bind_addr.port); rcu_read_lock(); list = rhltable_lookup(&sctp_transport_hashtable, &arg, sctp_hash_params); rhl_for_each_entry_rcu(transport, tmp, list, node) if (transport->asoc->ep == t->asoc->ep) { rcu_read_unlock(); err = -EEXIST; goto out; } rcu_read_unlock(); err = rhltable_insert_key(&sctp_transport_hashtable, &arg, &t->node, sctp_hash_params); out: if (err) pr_err_once("insert transport fail, errno %d\n", err); return err; } void sctp_unhash_transport(struct sctp_transport *t) { if (t->asoc->temp) return; rhltable_remove(&sctp_transport_hashtable, &t->node, sctp_hash_params); } /* return a transport with holding it */ struct sctp_transport *sctp_addrs_lookup_transport( struct net *net, const union sctp_addr *laddr, const union sctp_addr *paddr) { struct rhlist_head *tmp, *list; struct sctp_transport *t; struct sctp_hash_cmp_arg arg = { .paddr = paddr, .net = net, .lport = laddr->v4.sin_port, }; list = rhltable_lookup(&sctp_transport_hashtable, &arg, sctp_hash_params); rhl_for_each_entry_rcu(t, tmp, list, node) { if (!sctp_transport_hold(t)) continue; if (sctp_bind_addr_match(&t->asoc->base.bind_addr, laddr, sctp_sk(t->asoc->base.sk))) return t; sctp_transport_put(t); } return NULL; } /* return a transport without holding it, as it's only used under sock lock */ struct sctp_transport *sctp_epaddr_lookup_transport( const struct sctp_endpoint *ep, const union sctp_addr *paddr) { struct net *net = sock_net(ep->base.sk); struct rhlist_head *tmp, *list; struct sctp_transport *t; struct sctp_hash_cmp_arg arg = { .paddr = paddr, .net = net, .lport = htons(ep->base.bind_addr.port), }; list = rhltable_lookup(&sctp_transport_hashtable, &arg, sctp_hash_params); rhl_for_each_entry_rcu(t, tmp, list, node) if (ep == t->asoc->ep) return t; return NULL; } /* Look up an association. */ static struct sctp_association *__sctp_lookup_association( struct net *net, const union sctp_addr *local, const union sctp_addr *peer, struct sctp_transport **pt) { struct sctp_transport *t; struct sctp_association *asoc = NULL; t = sctp_addrs_lookup_transport(net, local, peer); if (!t) goto out; asoc = t->asoc; *pt = t; out: return asoc; } /* Look up an association. protected by RCU read lock */ static struct sctp_association *sctp_lookup_association(struct net *net, const union sctp_addr *laddr, const union sctp_addr *paddr, struct sctp_transport **transportp) { struct sctp_association *asoc; rcu_read_lock(); asoc = __sctp_lookup_association(net, laddr, paddr, transportp); rcu_read_unlock(); return asoc; } /* Is there an association matching the given local and peer addresses? */ int sctp_has_association(struct net *net, const union sctp_addr *laddr, const union sctp_addr *paddr) { struct sctp_association *asoc; struct sctp_transport *transport; if ((asoc = sctp_lookup_association(net, laddr, paddr, &transport))) { sctp_transport_put(transport); 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 net *net, 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); union sctp_params params; sctp_init_chunk_t *init; struct sctp_af *af; /* * 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(net, laddr, paddr, transportp); 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( struct net *net, struct sctp_chunkhdr *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->p.type)); if (unlikely(!af)) return NULL; af->from_addr_param(&paddr, param, peer_port, 0); return __sctp_lookup_association(net, 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 association. */ static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net, struct sk_buff *skb, const union sctp_addr *laddr, struct sctp_transport **transportp) { struct sctp_association *asoc = NULL; struct sctp_chunkhdr *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 = (struct sctp_chunkhdr *)skb->data; do { /* Break out if chunk length is less then minimal. */ if (ntohs(ch->length) < sizeof(*ch)) break; ch_end = ((__u8 *)ch) + SCTP_PAD4(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 || net->sctp.addip_noauth) asoc = __sctp_rcv_asconf_lookup( net, ch, laddr, sctp_hdr(skb)->source, transportp); default: break; } if (asoc) break; ch = (struct sctp_chunkhdr *)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 net *net, struct sk_buff *skb, const union sctp_addr *laddr, struct sctp_transport **transportp) { struct sctp_chunkhdr *ch; /* We do not allow GSO frames here as we need to linearize and * then cannot guarantee frame boundaries. This shouldn't be an * issue as packets hitting this are mostly INIT or INIT-ACK and * those cannot be on GSO-style anyway. */ if ((skb_shinfo(skb)->gso_type & SKB_GSO_SCTP) == SKB_GSO_SCTP) return NULL; ch = (struct sctp_chunkhdr *)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 (SCTP_PAD4(ntohs(ch->length)) > skb->len) return NULL; /* If this is INIT/INIT-ACK look inside the chunk too. */ if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK) return __sctp_rcv_init_lookup(net, skb, laddr, transportp); return __sctp_rcv_walk_lookup(net, skb, laddr, transportp); } /* Lookup an association for an inbound skb. */ static struct sctp_association *__sctp_rcv_lookup(struct net *net, 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(net, laddr, paddr, transportp); if (asoc) goto out; /* Further lookup for INIT/INIT-ACK packets. * SCTP Implementors Guide, 2.18 Handling of address * parameters within the INIT or INIT-ACK. */ asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp); if (asoc) goto out; if (paddr->sa.sa_family == AF_INET) pr_debug("sctp: asoc not found for src:%pI4:%d dst:%pI4:%d\n", &laddr->v4.sin_addr, ntohs(laddr->v4.sin_port), &paddr->v4.sin_addr, ntohs(paddr->v4.sin_port)); else pr_debug("sctp: asoc not found for src:%pI6:%d dst:%pI6:%d\n", &laddr->v6.sin6_addr, ntohs(laddr->v6.sin6_port), &paddr->v6.sin6_addr, ntohs(paddr->v6.sin6_port)); out: return asoc; }