Merge with Linux 2.5.59.

[linux-2.6/linux-mips.git] / net / sctp / input.c

/* SCTP kernel reference Implementation
 * Copyright (c) 1999-2000 Cisco, Inc.
 * Copyright (c) 1999-2001 Motorola, Inc.
 * Copyright (c) 2001 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/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 *);
sctp_association_t *__sctp_rcv_lookup(struct sk_buff *skb,
                                      const union sctp_addr *laddr,
                                      const union sctp_addr *paddr,
                                      sctp_transport_t **transportp);
sctp_endpoint_t *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr);


/* Calculate the SCTP checksum of an SCTP packet.  */
static inline int sctp_rcv_checksum(struct sk_buff *skb)
{
        struct sctphdr *sh;
        __u32 cmp, val;

        sh = (struct sctphdr *) skb->h.raw;
        cmp = ntohl(sh->checksum);
        val = count_crc((__u8 *)sh, skb->len);
        if (val != cmp) {
                /* CRC failure, dump it. */
                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;
        sctp_association_t *asoc;
        sctp_endpoint_t *ep = NULL;
        sctp_endpoint_common_t *rcvr;
        sctp_transport_t *transport = NULL;
        sctp_chunk_t *chunk;
        struct sctphdr *sh;
        union sctp_addr src;
        union sctp_addr dest;
        struct sctp_af *af;
        int ret = 0;

        if (skb->pkt_type!=PACKET_HOST)
                goto discard_it;

        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 bad_packet;
        if (sctp_rcv_checksum(skb) < 0)
                goto bad_packet;

        skb_pull(skb, sizeof(struct sctphdr));  

        af = sctp_get_af_specific(ipver2af(skb->nh.iph->version));
        if (unlikely(!af)) 
                goto bad_packet;

        /* 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) || !af->addr_valid(&dest))
                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))
                        goto discard_release;
        }

        /* Retrieve the common input handling substructure. */
        rcvr = asoc ? &asoc->base : &ep->base;
        sk = rcvr->sk;

        if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb))
                goto discard_release;

        /* Create an SCTP packet structure. */
        chunk = sctp_chunkify(skb, asoc, sk);
        if (!chunk) {
                ret = -ENOMEM;
                goto discard_release;
        }

        /* 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;

bad_packet:
#if 0 /* FIXME */
        SCTP_INC_STATS(SctpInErrs);
#endif /* FIXME*/

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)
{
        sctp_chunk_t *chunk;
        sctp_inqueue_t *inqueue;

        /* One day chunk will live inside the skb, but for
         * now this works.
         */
        chunk = (sctp_chunk_t *) skb;
        inqueue = &chunk->rcvr->inqueue;

        sctp_push_inqueue(inqueue, chunk);
        return 0;
}

/*
 * 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)
{
        /* This should probably involve a call to SCTPhandleICMP().  */
}

/*
 * 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;

        /* Scan through all the chunks in the packet.  */
        do {
                ch_end = ((__u8 *) ch) + WORD_ROUND(ntohs(ch->length));

                /* 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 (ch->type == SCTP_CID_SHUTDOWN_COMPLETE)
                        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 (ch->type == SCTP_CID_COOKIE_ACK)
                        goto discard;

                if (ch->type == SCTP_CID_ERROR) {
                        err = (sctp_errhdr_t *)(ch + sizeof(sctp_chunkhdr_t));
                        if (SCTP_ERROR_STALE_COOKIE == err->cause)
                                goto discard;
                }

                ch = (sctp_chunkhdr_t *) ch_end;
        } while (ch_end < skb->tail);

        return 0;

discard:
        return 1;
}

/* Insert endpoint into the hash table.  */
void __sctp_hash_endpoint(sctp_endpoint_t *ep)
{
        sctp_endpoint_common_t **epp;
        sctp_endpoint_common_t *epb;
        sctp_hashbucket_t *head;

        epb = &ep->base;

        epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);
        head = &sctp_proto.ep_hashbucket[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(sctp_endpoint_t *ep)
{
        sctp_local_bh_disable();
        __sctp_hash_endpoint(ep);
        sctp_local_bh_enable();
}

/* Remove endpoint from the hash table.  */
void __sctp_unhash_endpoint(sctp_endpoint_t *ep)
{
        sctp_hashbucket_t *head;
        sctp_endpoint_common_t *epb;

        epb = &ep->base;

        epb->hashent = sctp_ep_hashfn(epb->bind_addr.port);

        head = &sctp_proto.ep_hashbucket[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(sctp_endpoint_t *ep)
{
        sctp_local_bh_disable();
        __sctp_unhash_endpoint(ep);
        sctp_local_bh_enable();
}

/* Look up an endpoint. */
sctp_endpoint_t *__sctp_rcv_lookup_endpoint(const union sctp_addr *laddr)
{
        sctp_hashbucket_t *head;
        sctp_endpoint_common_t *epb;
        sctp_endpoint_t *ep;
        int hash;

        hash = sctp_ep_hashfn(laddr->v4.sin_port);
        head = &sctp_proto.ep_hashbucket[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;
}

/* Add an association to the hash. Local BH-safe. */
void sctp_hash_established(sctp_association_t *asoc)
{
        sctp_local_bh_disable();
        __sctp_hash_established(asoc);
        sctp_local_bh_enable();
}

/* Insert association into the hash table.  */
void __sctp_hash_established(sctp_association_t *asoc)
{
        sctp_endpoint_common_t **epp;
        sctp_endpoint_common_t *epb;
        sctp_hashbucket_t *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_proto.assoc_hashbucket[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);
}

/* Remove association from the hash table.  Local BH-safe. */
void sctp_unhash_established(sctp_association_t *asoc)
{
        sctp_local_bh_disable();
        __sctp_unhash_established(asoc);
        sctp_local_bh_enable();
}

/* Remove association from the hash table.  */
void __sctp_unhash_established(sctp_association_t *asoc)
{
        sctp_hashbucket_t *head;
        sctp_endpoint_common_t *epb;

        epb = &asoc->base;

        epb->hashent = sctp_assoc_hashfn(epb->bind_addr.port,
                                         asoc->peer.port);

        head = &sctp_proto.assoc_hashbucket[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);
}

/* Look up an association. */
sctp_association_t *__sctp_lookup_association(const union sctp_addr *laddr,
                                              const union sctp_addr *paddr,
                                              sctp_transport_t **transportp)
{
        sctp_hashbucket_t *head;
        sctp_endpoint_common_t *epb;
        sctp_association_t *asoc;
        sctp_transport_t *transport;
        int hash;

        /* Optimize here for direct hit, only listening connections can
         * have wildcards anyways.
         */
        hash = sctp_assoc_hashfn(laddr->v4.sin_port, paddr->v4.sin_port);
        head = &sctp_proto.assoc_hashbucket[hash];
        read_lock(&head->lock);
        for (epb = head->chain; epb; epb = epb->next) {
                asoc = sctp_assoc(epb);
                transport = sctp_assoc_is_match(asoc, laddr, paddr);
                if (transport)
                        goto hit;
        }

        read_unlock(&head->lock);

        return NULL;

hit:
        *transportp = transport;
        sctp_association_hold(asoc);
        sock_hold(epb->sk);
        read_unlock(&head->lock);
        return asoc;
}

/* Look up an association. BH-safe. */
sctp_association_t *sctp_lookup_association(const union sctp_addr *laddr,
                                            const union sctp_addr *paddr,
                                            sctp_transport_t **transportp)
{
        sctp_association_t *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)
{
        sctp_association_t *asoc;
        sctp_transport_t *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 sctp_association_t *__sctp_rcv_init_lookup(struct sk_buff *skb,
        const union sctp_addr *laddr, sctp_transport_t **transportp)
{
        sctp_association_t *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;

        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;
        }

        /*
         * 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. */
                if ((SCTP_PARAM_IPV4_ADDRESS != params.p->type) &&
                    (SCTP_PARAM_IPV6_ADDRESS != params.p->type))
                        continue;

                sctp_param2sockaddr(paddr, params.addr, ntohs(sh->source));
                asoc = __sctp_lookup_association(laddr, paddr, transportp);
                if (asoc)
                        return asoc;
        }

        return NULL;
}

/* Lookup an association for an inbound skb. */
sctp_association_t *__sctp_rcv_lookup(struct sk_buff *skb,
                                      const union sctp_addr *paddr,
                                      const union sctp_addr *laddr,
                                      sctp_transport_t **transportp)
{
        sctp_association_t *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;
}