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OpenCloudOS-Kernel/net/sctp/input.c

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/* 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);
}
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;
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);
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)))
{
sock_put(sk);
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);
sock_hold(sk);
rcvr = &ep->base;
}
if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
goto discard_release;
/*
* 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;
}
}
/* SCTP seems to always need a timestamp right now (FIXME) */
if (skb->tstamp.off_sec == 0) {
__net_timestamp(skb);
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_INPUT_CB(skb)->chunk = chunk;
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, skb);
else
sctp_backlog_rcv(sk, skb);
/* 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. */
sock_put(sk);
if (asoc)
sctp_association_put(asoc);
else
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 = SCTP_INPUT_CB(skb)->chunk;
struct sctp_inq *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_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, 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 = NULL;
struct sctp_transport *transport = NULL;
*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;
if (ntohl(sctphdr->vtag) != asoc->c.peer_vtag) {
ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
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(LINUX_MIB_LOCKDROPPEDICMPS);
*app = asoc;
*tpp = transport;
return sk;
out:
sock_put(sk);
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);
sock_put(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;
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_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, &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, 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.
*/
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;
}
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