endpointola.c

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/* SCTP kernel implementation
 * Copyright (c) 1999-2000 Cisco, Inc.
 * Copyright (c) 1999-2001 Motorola, Inc.
 * Copyright (c) 2001-2002 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
 *
 * This abstraction represents an SCTP endpoint.
 *
 * The 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.
 *
 * The SCTP implementation is distributed in the hope that it
 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
 *                 ************************
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNU CC; see the file COPYING.  If not, write to
 * the Free Software Foundation, 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * Please send any bug reports or fixes you make to the
 * email address(es):
 *    lksctp developers <[email protected]>
 *
 * Or submit a bug report through the following website:
 *    http://www.sf.net/projects/lksctp
 *
 * Written or modified by:
 *    La Monte H.P. Yarroll <[email protected]>
 *    Karl Knutson <[email protected]>
 *    Jon Grimm <[email protected]>
 *    Daisy Chang <[email protected]>
 *    Dajiang Zhang <[email protected]>
 *
 * 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/slab.h>
#include <linux/in.h>
#include <linux/random.h>   /* get_random_bytes() */
#include <linux/crypto.h>
#include <net/sock.h>
#include <net/ipv6.h>
#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>

/* Forward declarations for internal helpers. */
static void sctp_endpoint_bh_rcv(struct work_struct *work);

/*
 * Initialize the base fields of the endpoint structure.
 */
static struct sctp_endpoint *sctp_endpoint_init(struct sctp_endpoint *ep,
                        struct sock *sk,
                        gfp_t gfp)
{
    struct net *net = sock_net(sk);
    struct sctp_hmac_algo_param *auth_hmacs = NULL;
    struct sctp_chunks_param *auth_chunks = NULL;
    struct sctp_shared_key *null_key;
    int err;

    ep->digest = kzalloc(SCTP_SIGNATURE_SIZE, gfp);
    if (!ep->digest)
        return NULL;

    if (net->sctp.auth_enable) {
        /* Allocate space for HMACS and CHUNKS authentication
         * variables.  There are arrays that we encode directly
         * into parameters to make the rest of the operations easier.
         */
        auth_hmacs = kzalloc(sizeof(sctp_hmac_algo_param_t) +
                sizeof(__u16) * SCTP_AUTH_NUM_HMACS, gfp);
        if (!auth_hmacs)
            goto nomem;

        auth_chunks = kzalloc(sizeof(sctp_chunks_param_t) +
                    SCTP_NUM_CHUNK_TYPES, gfp);
        if (!auth_chunks)
            goto nomem;

        /* Initialize the HMACS parameter.
         * SCTP-AUTH: Section 3.3
         *    Every endpoint supporting SCTP chunk authentication MUST
         *    support the HMAC based on the SHA-1 algorithm.
         */
        auth_hmacs->param_hdr.type = SCTP_PARAM_HMAC_ALGO;
        auth_hmacs->param_hdr.length =
                    htons(sizeof(sctp_paramhdr_t) + 2);
        auth_hmacs->hmac_ids[0] = htons(SCTP_AUTH_HMAC_ID_SHA1);

        /* Initialize the CHUNKS parameter */
        auth_chunks->param_hdr.type = SCTP_PARAM_CHUNKS;
        auth_chunks->param_hdr.length = htons(sizeof(sctp_paramhdr_t));

        /* If the Add-IP functionality is enabled, we must
         * authenticate, ASCONF and ASCONF-ACK chunks
         */
        if (net->sctp.addip_enable) {
            auth_chunks->chunks[0] = SCTP_CID_ASCONF;
            auth_chunks->chunks[1] = SCTP_CID_ASCONF_ACK;
            auth_chunks->param_hdr.length =
                    htons(sizeof(sctp_paramhdr_t) + 2);
        }
    }

    /* Initialize the base structure. */
    /* What type of endpoint are we?  */
    ep->base.type = SCTP_EP_TYPE_SOCKET;

    /* Initialize the basic object fields. */
    atomic_set(&ep->base.refcnt, 1);
    ep->base.dead = 0;
    ep->base.malloced = 1;

    /* Create an input queue.  */
    sctp_inq_init(&ep->base.inqueue);

    /* Set its top-half handler */
    sctp_inq_set_th_handler(&ep->base.inqueue, sctp_endpoint_bh_rcv);

    /* Initialize the bind addr area */
    sctp_bind_addr_init(&ep->base.bind_addr, 0);

    /* Remember who we are attached to.  */
    ep->base.sk = sk;
    sock_hold(ep->base.sk);

    /* Create the lists of associations.  */
    INIT_LIST_HEAD(&ep->asocs);

    /* Use SCTP specific send buffer space queues.  */
    ep->sndbuf_policy = net->sctp.sndbuf_policy;

    sk->sk_data_ready = sctp_data_ready;
    sk->sk_write_space = sctp_write_space;
    sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);

    /* Get the receive buffer policy for this endpoint */
    ep->rcvbuf_policy = net->sctp.rcvbuf_policy;

    /* Initialize the secret key used with cookie. */
    get_random_bytes(&ep->secret_key[0], SCTP_SECRET_SIZE);
    ep->last_key = ep->current_key = 0;
    ep->key_changed_at = jiffies;

    /* SCTP-AUTH extensions*/
    INIT_LIST_HEAD(&ep->endpoint_shared_keys);
    null_key = sctp_auth_shkey_create(0, GFP_KERNEL);
    if (!null_key)
        goto nomem;

    list_add(&null_key->key_list, &ep->endpoint_shared_keys);

    /* Allocate and initialize transorms arrays for suported HMACs. */
    err = sctp_auth_init_hmacs(ep, gfp);
    if (err)
        goto nomem_hmacs;

    /* Add the null key to the endpoint shared keys list and
     * set the hmcas and chunks pointers.
     */
    ep->auth_hmacs_list = auth_hmacs;
    ep->auth_chunk_list = auth_chunks;

    return ep;

nomem_hmacs:
    sctp_auth_destroy_keys(&ep->endpoint_shared_keys);
nomem:
    /* Free all allocations */
    kfree(auth_hmacs);
    kfree(auth_chunks);
    kfree(ep->digest);
    return NULL;

}

/* Create a sctp_endpoint with all that boring stuff initialized.
 * Returns NULL if there isn't enough memory.
 */
struct sctp_endpoint *sctp_endpoint_new(struct sock *sk, gfp_t gfp)
{
    struct sctp_endpoint *ep;

    /* Build a local endpoint. */
    ep = t_new(struct sctp_endpoint, gfp);
    if (!ep)
        goto fail;
    if (!sctp_endpoint_init(ep, sk, gfp))
        goto fail_init;
    ep->base.malloced = 1;
    SCTP_DBG_OBJCNT_INC(ep);
    return ep;

fail_init:
    kfree(ep);
fail:
    return NULL;
}

/* Add an association to an endpoint.  */
void sctp_endpoint_add_asoc(struct sctp_endpoint *ep,
                struct sctp_association *asoc)
{
    struct sock *sk = ep->base.sk;

    /* If this is a temporary association, don't bother
     * since we'll be removing it shortly and don't
     * want anyone to find it anyway.
     */
    if (asoc->temp)
        return;

    /* Now just add it to our list of asocs */
    list_add_tail(&asoc->asocs, &ep->asocs);

    /* Increment the backlog value for a TCP-style listening socket. */
    if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
        sk->sk_ack_backlog++;
}

/* Free the endpoint structure.  Delay cleanup until
 * all users have released their reference count on this structure.
 */
void sctp_endpoint_free(struct sctp_endpoint *ep)
{
    ep->base.dead = 1;

    ep->base.sk->sk_state = SCTP_SS_CLOSED;

    /* Unlink this endpoint, so we can't find it again! */
    sctp_unhash_endpoint(ep);

    sctp_endpoint_put(ep);
}

/* Final destructor for endpoint.  */
static void sctp_endpoint_destroy(struct sctp_endpoint *ep)
{
    SCTP_ASSERT(ep->base.dead, "Endpoint is not dead", return);

    /* Free up the HMAC transform. */
    crypto_free_hash(sctp_sk(ep->base.sk)->hmac);

    /* Free the digest buffer */
    kfree(ep->digest);

    /* SCTP-AUTH: Free up AUTH releated data such as shared keys
     * chunks and hmacs arrays that were allocated
     */
    sctp_auth_destroy_keys(&ep->endpoint_shared_keys);
    kfree(ep->auth_hmacs_list);
    kfree(ep->auth_chunk_list);

    /* AUTH - Free any allocated HMAC transform containers */
    sctp_auth_destroy_hmacs(ep->auth_hmacs);

    /* Cleanup. */
    sctp_inq_free(&ep->base.inqueue);
    sctp_bind_addr_free(&ep->base.bind_addr);

    /* Remove and free the port */
    if (sctp_sk(ep->base.sk)->bind_hash)
        sctp_put_port(ep->base.sk);

    /* Give up our hold on the sock. */
    if (ep->base.sk)
        sock_put(ep->base.sk);

    /* Finally, free up our memory. */
    if (ep->base.malloced) {
        kfree(ep);
        SCTP_DBG_OBJCNT_DEC(ep);
    }
}

/* Hold a reference to an endpoint. */
void sctp_endpoint_hold(struct sctp_endpoint *ep)
{
    atomic_inc(&ep->base.refcnt);
}

/* Release a reference to an endpoint and clean up if there are
 * no more references.
 */
void sctp_endpoint_put(struct sctp_endpoint *ep)
{
    if (atomic_dec_and_test(&ep->base.refcnt))
        sctp_endpoint_destroy(ep);
}

/* Is this the endpoint we are looking for?  */
struct sctp_endpoint *sctp_endpoint_is_match(struct sctp_endpoint *ep,
                           struct net *net,
                           const union sctp_addr *laddr)
{
    struct sctp_endpoint *retval = NULL;

    if ((htons(ep->base.bind_addr.port) == laddr->v4.sin_port) &&
        net_eq(sock_net(ep->base.sk), net)) {
        if (sctp_bind_addr_match(&ep->base.bind_addr, laddr,
                     sctp_sk(ep->base.sk)))
            retval = ep;
    }

    return retval;
}

/* Find the association that goes with this chunk.
 * We do a linear search of the associations for this endpoint.
 * We return the matching transport address too.
 */
static struct sctp_association *__sctp_endpoint_lookup_assoc(
    const struct sctp_endpoint *ep,
    const union sctp_addr *paddr,
    struct sctp_transport **transport)
{
    struct sctp_association *asoc = NULL;
    struct sctp_association *tmp;
    struct sctp_transport *t = NULL;
    struct sctp_hashbucket *head;
    struct sctp_ep_common *epb;
    struct hlist_node *node;
    int hash;
    int rport;

    *transport = NULL;

    /* If the local port is not set, there can't be any associations
     * on this endpoint.
     */
    if (!ep->base.bind_addr.port)
        goto out;

    rport = ntohs(paddr->v4.sin_port);

    hash = sctp_assoc_hashfn(sock_net(ep->base.sk), ep->base.bind_addr.port,
                 rport);
    head = &sctp_assoc_hashtable[hash];
    read_lock(&head->lock);
    sctp_for_each_hentry(epb, node, &head->chain) {
        tmp = sctp_assoc(epb);
        if (tmp->ep != ep || rport != tmp->peer.port)
            continue;

        t = sctp_assoc_lookup_paddr(tmp, paddr);
        if (t) {
            asoc = tmp;
            *transport = t;
            break;
        }
    }
    read_unlock(&head->lock);
out:
    return asoc;
}

/* Lookup association on an endpoint based on a peer address.  BH-safe.  */
struct sctp_association *sctp_endpoint_lookup_assoc(
    const struct sctp_endpoint *ep,
    const union sctp_addr *paddr,
    struct sctp_transport **transport)
{
    struct sctp_association *asoc;

    sctp_local_bh_disable();
    asoc = __sctp_endpoint_lookup_assoc(ep, paddr, transport);
    sctp_local_bh_enable();

    return asoc;
}

/* Look for any peeled off association from the endpoint that matches the
 * given peer address.
 */
int sctp_endpoint_is_peeled_off(struct sctp_endpoint *ep,
                const union sctp_addr *paddr)
{
    struct sctp_sockaddr_entry *addr;
    struct sctp_bind_addr *bp;
    struct net *net = sock_net(ep->base.sk);

    bp = &ep->base.bind_addr;
    /* This function is called with the socket lock held,
     * so the address_list can not change.
     */
    list_for_each_entry(addr, &bp->address_list, list) {
        if (sctp_has_association(net, &addr->a, paddr))
            return 1;
    }

    return 0;
}

/* Do delayed input processing.  This is scheduled by sctp_rcv().
 * This may be called on BH or task time.
 */
static void sctp_endpoint_bh_rcv(struct work_struct *work)
{
    struct sctp_endpoint *ep =
        container_of(work, struct sctp_endpoint,
                 base.inqueue.immediate);
    struct sctp_association *asoc;
    struct sock *sk;
    struct net *net;
    struct sctp_transport *transport;
    struct sctp_chunk *chunk;
    struct sctp_inq *inqueue;
    sctp_subtype_t subtype;
    sctp_state_t state;
    int error = 0;
    int first_time = 1; /* is this the first time through the loop */

    if (ep->base.dead)
        return;

    asoc = NULL;
    inqueue = &ep->base.inqueue;
    sk = ep->base.sk;
    net = sock_net(sk);

    while (NULL != (chunk = sctp_inq_pop(inqueue))) {
        subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);

        /* If the first chunk in the packet is AUTH, do special
         * processing specified in Section 6.3 of SCTP-AUTH spec
         */
        if (first_time && (subtype.chunk == SCTP_CID_AUTH)) {
            struct sctp_chunkhdr *next_hdr;

            next_hdr = sctp_inq_peek(inqueue);
            if (!next_hdr)
                goto normal;

            /* If the next chunk is COOKIE-ECHO, skip the AUTH
             * chunk while saving a pointer to it so we can do
             * Authentication later (during cookie-echo
             * processing).
             */
            if (next_hdr->type == SCTP_CID_COOKIE_ECHO) {
                chunk->auth_chunk = skb_clone(chunk->skb,
                                GFP_ATOMIC);
                chunk->auth = 1;
                continue;
            }
        }
normal:
        /* We might have grown an association since last we
         * looked, so try again.
         *
         * This happens when we've just processed our
         * COOKIE-ECHO chunk.
         */
        if (NULL == chunk->asoc) {
            asoc = sctp_endpoint_lookup_assoc(ep,
                              sctp_source(chunk),
                              &transport);
            chunk->asoc = asoc;
            chunk->transport = transport;
        }

        state = asoc ? asoc->state : SCTP_STATE_CLOSED;
        if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
            continue;

        /* Remember where the last DATA chunk came from so we
         * know where to send the SACK.
         */
        if (asoc && sctp_chunk_is_data(chunk))
            asoc->peer.last_data_from = chunk->transport;
        else
            SCTP_INC_STATS(sock_net(ep->base.sk), SCTP_MIB_INCTRLCHUNKS);

        if (chunk->transport)
            chunk->transport->last_time_heard = jiffies;

        error = sctp_do_sm(net, SCTP_EVENT_T_CHUNK, subtype, state,
                   ep, asoc, chunk, GFP_ATOMIC);

        if (error && chunk)
            chunk->pdiscard = 1;

        /* Check to see if the endpoint is freed in response to
         * the incoming chunk. If so, get out of the while loop.
         */
        if (!sctp_sk(sk)->ep)
            break;

        if (first_time)
            first_time = 0;
    }
}