auth.c

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/* SCTP kernel implementation
 * (C) Copyright 2007 Hewlett-Packard Development Company, L.P.
 *
 * This file is part of the SCTP kernel implementation
 *
 * 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, 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:
 *   Vlad Yasevich     <[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/slab.h>
#include <linux/types.h>
#include <linux/crypto.h>
#include <linux/scatterlist.h>
#include <net/sctp/sctp.h>
#include <net/sctp/auth.h>

static struct sctp_hmac sctp_hmac_list[SCTP_AUTH_NUM_HMACS] = {
    {
        /* id 0 is reserved.  as all 0 */
        .hmac_id = SCTP_AUTH_HMAC_ID_RESERVED_0,
    },
    {
        .hmac_id = SCTP_AUTH_HMAC_ID_SHA1,
        .hmac_name="hmac(sha1)",
        .hmac_len = SCTP_SHA1_SIG_SIZE,
    },
    {
        /* id 2 is reserved as well */
        .hmac_id = SCTP_AUTH_HMAC_ID_RESERVED_2,
    },
#if defined (CONFIG_CRYPTO_SHA256) || defined (CONFIG_CRYPTO_SHA256_MODULE)
    {
        .hmac_id = SCTP_AUTH_HMAC_ID_SHA256,
        .hmac_name="hmac(sha256)",
        .hmac_len = SCTP_SHA256_SIG_SIZE,
    }
#endif
};


void sctp_auth_key_put(struct sctp_auth_bytes *key)
{
    if (!key)
        return;

    if (atomic_dec_and_test(&key->refcnt)) {
        kfree(key);
        SCTP_DBG_OBJCNT_DEC(keys);
    }
}

/* Create a new key structure of a given length */
static struct sctp_auth_bytes *sctp_auth_create_key(__u32 key_len, gfp_t gfp)
{
    struct sctp_auth_bytes *key;

    /* Verify that we are not going to overflow INT_MAX */
    if (key_len > (INT_MAX - sizeof(struct sctp_auth_bytes)))
        return NULL;

    /* Allocate the shared key */
    key = kmalloc(sizeof(struct sctp_auth_bytes) + key_len, gfp);
    if (!key)
        return NULL;

    key->len = key_len;
    atomic_set(&key->refcnt, 1);
    SCTP_DBG_OBJCNT_INC(keys);

    return key;
}

/* Create a new shared key container with a give key id */
struct sctp_shared_key *sctp_auth_shkey_create(__u16 key_id, gfp_t gfp)
{
    struct sctp_shared_key *new;

    /* Allocate the shared key container */
    new = kzalloc(sizeof(struct sctp_shared_key), gfp);
    if (!new)
        return NULL;

    INIT_LIST_HEAD(&new->key_list);
    new->key_id = key_id;

    return new;
}

/* Free the shared key structure */
static void sctp_auth_shkey_free(struct sctp_shared_key *sh_key)
{
    BUG_ON(!list_empty(&sh_key->key_list));
    sctp_auth_key_put(sh_key->key);
    sh_key->key = NULL;
    kfree(sh_key);
}

/* Destroy the entire key list.  This is done during the
 * associon and endpoint free process.
 */
void sctp_auth_destroy_keys(struct list_head *keys)
{
    struct sctp_shared_key *ep_key;
    struct sctp_shared_key *tmp;

    if (list_empty(keys))
        return;

    key_for_each_safe(ep_key, tmp, keys) {
        list_del_init(&ep_key->key_list);
        sctp_auth_shkey_free(ep_key);
    }
}

/* Compare two byte vectors as numbers.  Return values
 * are:
 *    0 - vectors are equal
 *  < 0 - vector 1 is smaller than vector2
 *  > 0 - vector 1 is greater than vector2
 *
 * Algorithm is:
 *  This is performed by selecting the numerically smaller key vector...
 *  If the key vectors are equal as numbers but differ in length ...
 *  the shorter vector is considered smaller
 *
 * Examples (with small values):
 *  000123456789 > 123456789 (first number is longer)
 *  000123456789 < 234567891 (second number is larger numerically)
 *  123456789 > 2345678      (first number is both larger & longer)
 */
static int sctp_auth_compare_vectors(struct sctp_auth_bytes *vector1,
                  struct sctp_auth_bytes *vector2)
{
    int diff;
    int i;
    const __u8 *longer;

    diff = vector1->len - vector2->len;
    if (diff) {
        longer = (diff > 0) ? vector1->data : vector2->data;

        /* Check to see if the longer number is
         * lead-zero padded.  If it is not, it
         * is automatically larger numerically.
         */
        for (i = 0; i < abs(diff); i++ ) {
            if (longer[i] != 0)
                return diff;
        }
    }

    /* lengths are the same, compare numbers */
    return memcmp(vector1->data, vector2->data, vector1->len);
}

/*
 * Create a key vector as described in SCTP-AUTH, Section 6.1
 *    The RANDOM parameter, the CHUNKS parameter and the HMAC-ALGO
 *    parameter sent by each endpoint are concatenated as byte vectors.
 *    These parameters include the parameter type, parameter length, and
 *    the parameter value, but padding is omitted; all padding MUST be
 *    removed from this concatenation before proceeding with further
 *    computation of keys.  Parameters which were not sent are simply
 *    omitted from the concatenation process.  The resulting two vectors
 *    are called the two key vectors.
 */
static struct sctp_auth_bytes *sctp_auth_make_key_vector(
            sctp_random_param_t *random,
            sctp_chunks_param_t *chunks,
            sctp_hmac_algo_param_t *hmacs,
            gfp_t gfp)
{
    struct sctp_auth_bytes *new;
    __u32   len;
    __u32   offset = 0;

    len = ntohs(random->param_hdr.length) + ntohs(hmacs->param_hdr.length);
        if (chunks)
        len += ntohs(chunks->param_hdr.length);

    new = kmalloc(sizeof(struct sctp_auth_bytes) + len, gfp);
    if (!new)
        return NULL;

    new->len = len;

    memcpy(new->data, random, ntohs(random->param_hdr.length));
    offset += ntohs(random->param_hdr.length);

    if (chunks) {
        memcpy(new->data + offset, chunks,
            ntohs(chunks->param_hdr.length));
        offset += ntohs(chunks->param_hdr.length);
    }

    memcpy(new->data + offset, hmacs, ntohs(hmacs->param_hdr.length));

    return new;
}


/* Make a key vector based on our local parameters */
static struct sctp_auth_bytes *sctp_auth_make_local_vector(
                    const struct sctp_association *asoc,
                    gfp_t gfp)
{
    return sctp_auth_make_key_vector(
                    (sctp_random_param_t*)asoc->c.auth_random,
                    (sctp_chunks_param_t*)asoc->c.auth_chunks,
                    (sctp_hmac_algo_param_t*)asoc->c.auth_hmacs,
                    gfp);
}

/* Make a key vector based on peer's parameters */
static struct sctp_auth_bytes *sctp_auth_make_peer_vector(
                    const struct sctp_association *asoc,
                    gfp_t gfp)
{
    return sctp_auth_make_key_vector(asoc->peer.peer_random,
                     asoc->peer.peer_chunks,
                     asoc->peer.peer_hmacs,
                     gfp);
}


/* Set the value of the association shared key base on the parameters
 * given.  The algorithm is:
 *    From the endpoint pair shared keys and the key vectors the
 *    association shared keys are computed.  This is performed by selecting
 *    the numerically smaller key vector and concatenating it to the
 *    endpoint pair shared key, and then concatenating the numerically
 *    larger key vector to that.  The result of the concatenation is the
 *    association shared key.
 */
static struct sctp_auth_bytes *sctp_auth_asoc_set_secret(
            struct sctp_shared_key *ep_key,
            struct sctp_auth_bytes *first_vector,
            struct sctp_auth_bytes *last_vector,
            gfp_t gfp)
{
    struct sctp_auth_bytes *secret;
    __u32 offset = 0;
    __u32 auth_len;

    auth_len = first_vector->len + last_vector->len;
    if (ep_key->key)
        auth_len += ep_key->key->len;

    secret = sctp_auth_create_key(auth_len, gfp);
    if (!secret)
        return NULL;

    if (ep_key->key) {
        memcpy(secret->data, ep_key->key->data, ep_key->key->len);
        offset += ep_key->key->len;
    }

    memcpy(secret->data + offset, first_vector->data, first_vector->len);
    offset += first_vector->len;

    memcpy(secret->data + offset, last_vector->data, last_vector->len);

    return secret;
}

/* Create an association shared key.  Follow the algorithm
 * described in SCTP-AUTH, Section 6.1
 */
static struct sctp_auth_bytes *sctp_auth_asoc_create_secret(
                 const struct sctp_association *asoc,
                 struct sctp_shared_key *ep_key,
                 gfp_t gfp)
{
    struct sctp_auth_bytes *local_key_vector;
    struct sctp_auth_bytes *peer_key_vector;
    struct sctp_auth_bytes  *first_vector,
                *last_vector;
    struct sctp_auth_bytes  *secret = NULL;
    int cmp;


    /* Now we need to build the key vectors
     * SCTP-AUTH , Section 6.1
     *    The RANDOM parameter, the CHUNKS parameter and the HMAC-ALGO
     *    parameter sent by each endpoint are concatenated as byte vectors.
     *    These parameters include the parameter type, parameter length, and
     *    the parameter value, but padding is omitted; all padding MUST be
     *    removed from this concatenation before proceeding with further
     *    computation of keys.  Parameters which were not sent are simply
     *    omitted from the concatenation process.  The resulting two vectors
     *    are called the two key vectors.
     */

    local_key_vector = sctp_auth_make_local_vector(asoc, gfp);
    peer_key_vector = sctp_auth_make_peer_vector(asoc, gfp);

    if (!peer_key_vector || !local_key_vector)
        goto out;

    /* Figure out the order in which the key_vectors will be
     * added to the endpoint shared key.
     * SCTP-AUTH, Section 6.1:
     *   This is performed by selecting the numerically smaller key
     *   vector and concatenating it to the endpoint pair shared
     *   key, and then concatenating the numerically larger key
     *   vector to that.  If the key vectors are equal as numbers
     *   but differ in length, then the concatenation order is the
     *   endpoint shared key, followed by the shorter key vector,
     *   followed by the longer key vector.  Otherwise, the key
     *   vectors are identical, and may be concatenated to the
     *   endpoint pair key in any order.
     */
    cmp = sctp_auth_compare_vectors(local_key_vector,
                    peer_key_vector);
    if (cmp < 0) {
        first_vector = local_key_vector;
        last_vector = peer_key_vector;
    } else {
        first_vector = peer_key_vector;
        last_vector = local_key_vector;
    }

    secret = sctp_auth_asoc_set_secret(ep_key, first_vector, last_vector,
                        gfp);
out:
    kfree(local_key_vector);
    kfree(peer_key_vector);

    return secret;
}

/*
 * Populate the association overlay list with the list
 * from the endpoint.
 */
int sctp_auth_asoc_copy_shkeys(const struct sctp_endpoint *ep,
                struct sctp_association *asoc,
                gfp_t gfp)
{
    struct sctp_shared_key *sh_key;
    struct sctp_shared_key *new;

    BUG_ON(!list_empty(&asoc->endpoint_shared_keys));

    key_for_each(sh_key, &ep->endpoint_shared_keys) {
        new = sctp_auth_shkey_create(sh_key->key_id, gfp);
        if (!new)
            goto nomem;

        new->key = sh_key->key;
        sctp_auth_key_hold(new->key);
        list_add(&new->key_list, &asoc->endpoint_shared_keys);
    }

    return 0;

nomem:
    sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
    return -ENOMEM;
}


/* Public interface to creat the association shared key.
 * See code above for the algorithm.
 */
int sctp_auth_asoc_init_active_key(struct sctp_association *asoc, gfp_t gfp)
{
    struct net *net = sock_net(asoc->base.sk);
    struct sctp_auth_bytes  *secret;
    struct sctp_shared_key *ep_key;

    /* If we don't support AUTH, or peer is not capable
     * we don't need to do anything.
     */
    if (!net->sctp.auth_enable || !asoc->peer.auth_capable)
        return 0;

    /* If the key_id is non-zero and we couldn't find an
     * endpoint pair shared key, we can't compute the
     * secret.
     * For key_id 0, endpoint pair shared key is a NULL key.
     */
    ep_key = sctp_auth_get_shkey(asoc, asoc->active_key_id);
    BUG_ON(!ep_key);

    secret = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
    if (!secret)
        return -ENOMEM;

    sctp_auth_key_put(asoc->asoc_shared_key);
    asoc->asoc_shared_key = secret;

    return 0;
}


/* Find the endpoint pair shared key based on the key_id */
struct sctp_shared_key *sctp_auth_get_shkey(
                const struct sctp_association *asoc,
                __u16 key_id)
{
    struct sctp_shared_key *key;

    /* First search associations set of endpoint pair shared keys */
    key_for_each(key, &asoc->endpoint_shared_keys) {
        if (key->key_id == key_id)
            return key;
    }

    return NULL;
}

/*
 * Initialize all the possible digest transforms that we can use.  Right now
 * now, the supported digests are SHA1 and SHA256.  We do this here once
 * because of the restrictiong that transforms may only be allocated in
 * user context.  This forces us to pre-allocated all possible transforms
 * at the endpoint init time.
 */
int sctp_auth_init_hmacs(struct sctp_endpoint *ep, gfp_t gfp)
{
    struct net *net = sock_net(ep->base.sk);
    struct crypto_hash *tfm = NULL;
    __u16   id;

    /* if the transforms are already allocted, we are done */
    if (!net->sctp.auth_enable) {
        ep->auth_hmacs = NULL;
        return 0;
    }

    if (ep->auth_hmacs)
        return 0;

    /* Allocated the array of pointers to transorms */
    ep->auth_hmacs = kzalloc(
                sizeof(struct crypto_hash *) * SCTP_AUTH_NUM_HMACS,
                gfp);
    if (!ep->auth_hmacs)
        return -ENOMEM;

    for (id = 0; id < SCTP_AUTH_NUM_HMACS; id++) {

        /* See is we support the id.  Supported IDs have name and
         * length fields set, so that we can allocated and use
         * them.  We can safely just check for name, for without the
         * name, we can't allocate the TFM.
         */
        if (!sctp_hmac_list[id].hmac_name)
            continue;

        /* If this TFM has been allocated, we are all set */
        if (ep->auth_hmacs[id])
            continue;

        /* Allocate the ID */
        tfm = crypto_alloc_hash(sctp_hmac_list[id].hmac_name, 0,
                    CRYPTO_ALG_ASYNC);
        if (IS_ERR(tfm))
            goto out_err;

        ep->auth_hmacs[id] = tfm;
    }

    return 0;

out_err:
    /* Clean up any successful allocations */
    sctp_auth_destroy_hmacs(ep->auth_hmacs);
    return -ENOMEM;
}

/* Destroy the hmac tfm array */
void sctp_auth_destroy_hmacs(struct crypto_hash *auth_hmacs[])
{
    int i;

    if (!auth_hmacs)
        return;

    for (i = 0; i < SCTP_AUTH_NUM_HMACS; i++)
    {
        if (auth_hmacs[i])
            crypto_free_hash(auth_hmacs[i]);
    }
    kfree(auth_hmacs);
}


struct sctp_hmac *sctp_auth_get_hmac(__u16 hmac_id)
{
    return &sctp_hmac_list[hmac_id];
}

/* Get an hmac description information that we can use to build
 * the AUTH chunk
 */
struct sctp_hmac *sctp_auth_asoc_get_hmac(const struct sctp_association *asoc)
{
    struct sctp_hmac_algo_param *hmacs;
    __u16 n_elt;
    __u16 id = 0;
    int i;

    /* If we have a default entry, use it */
    if (asoc->default_hmac_id)
        return &sctp_hmac_list[asoc->default_hmac_id];

    /* Since we do not have a default entry, find the first entry
     * we support and return that.  Do not cache that id.
     */
    hmacs = asoc->peer.peer_hmacs;
    if (!hmacs)
        return NULL;

    n_elt = (ntohs(hmacs->param_hdr.length) - sizeof(sctp_paramhdr_t)) >> 1;
    for (i = 0; i < n_elt; i++) {
        id = ntohs(hmacs->hmac_ids[i]);

        /* Check the id is in the supported range */
        if (id > SCTP_AUTH_HMAC_ID_MAX) {
            id = 0;
            continue;
        }

        /* See is we support the id.  Supported IDs have name and
         * length fields set, so that we can allocated and use
         * them.  We can safely just check for name, for without the
         * name, we can't allocate the TFM.
         */
        if (!sctp_hmac_list[id].hmac_name) {
            id = 0;
            continue;
        }

        break;
    }

    if (id == 0)
        return NULL;

    return &sctp_hmac_list[id];
}

static int __sctp_auth_find_hmacid(__be16 *hmacs, int n_elts, __be16 hmac_id)
{
    int  found = 0;
    int  i;

    for (i = 0; i < n_elts; i++) {
        if (hmac_id == hmacs[i]) {
            found = 1;
            break;
        }
    }

    return found;
}

/* See if the HMAC_ID is one that we claim as supported */
int sctp_auth_asoc_verify_hmac_id(const struct sctp_association *asoc,
                    __be16 hmac_id)
{
    struct sctp_hmac_algo_param *hmacs;
    __u16 n_elt;

    if (!asoc)
        return 0;

    hmacs = (struct sctp_hmac_algo_param *)asoc->c.auth_hmacs;
    n_elt = (ntohs(hmacs->param_hdr.length) - sizeof(sctp_paramhdr_t)) >> 1;

    return __sctp_auth_find_hmacid(hmacs->hmac_ids, n_elt, hmac_id);
}


/* Cache the default HMAC id.  This to follow this text from SCTP-AUTH:
 * Section 6.1:
 *   The receiver of a HMAC-ALGO parameter SHOULD use the first listed
 *   algorithm it supports.
 */
void sctp_auth_asoc_set_default_hmac(struct sctp_association *asoc,
                     struct sctp_hmac_algo_param *hmacs)
{
    struct sctp_endpoint *ep;
    __u16   id;
    int i;
    int n_params;

    /* if the default id is already set, use it */
    if (asoc->default_hmac_id)
        return;

    n_params = (ntohs(hmacs->param_hdr.length)
                - sizeof(sctp_paramhdr_t)) >> 1;
    ep = asoc->ep;
    for (i = 0; i < n_params; i++) {
        id = ntohs(hmacs->hmac_ids[i]);

        /* Check the id is in the supported range */
        if (id > SCTP_AUTH_HMAC_ID_MAX)
            continue;

        /* If this TFM has been allocated, use this id */
        if (ep->auth_hmacs[id]) {
            asoc->default_hmac_id = id;
            break;
        }
    }
}


/* Check to see if the given chunk is supposed to be authenticated */
static int __sctp_auth_cid(sctp_cid_t chunk, struct sctp_chunks_param *param)
{
    unsigned short len;
    int found = 0;
    int i;

    if (!param || param->param_hdr.length == 0)
        return 0;

    len = ntohs(param->param_hdr.length) - sizeof(sctp_paramhdr_t);

    /* SCTP-AUTH, Section 3.2
     *    The chunk types for INIT, INIT-ACK, SHUTDOWN-COMPLETE and AUTH
     *    chunks MUST NOT be listed in the CHUNKS parameter.  However, if
     *    a CHUNKS parameter is received then the types for INIT, INIT-ACK,
     *    SHUTDOWN-COMPLETE and AUTH chunks MUST be ignored.
     */
    for (i = 0; !found && i < len; i++) {
        switch (param->chunks[i]) {
            case SCTP_CID_INIT:
            case SCTP_CID_INIT_ACK:
            case SCTP_CID_SHUTDOWN_COMPLETE:
            case SCTP_CID_AUTH:
            break;

            default:
            if (param->chunks[i] == chunk)
                found = 1;
            break;
        }
    }

    return found;
}

/* Check if peer requested that this chunk is authenticated */
int sctp_auth_send_cid(sctp_cid_t chunk, const struct sctp_association *asoc)
{
    struct net  *net;
    if (!asoc)
        return 0;

    net = sock_net(asoc->base.sk);
    if (!net->sctp.auth_enable || !asoc->peer.auth_capable)
        return 0;

    return __sctp_auth_cid(chunk, asoc->peer.peer_chunks);
}

/* Check if we requested that peer authenticate this chunk. */
int sctp_auth_recv_cid(sctp_cid_t chunk, const struct sctp_association *asoc)
{
    struct net *net;
    if (!asoc)
        return 0;

    net = sock_net(asoc->base.sk);
    if (!net->sctp.auth_enable)
        return 0;

    return __sctp_auth_cid(chunk,
                  (struct sctp_chunks_param *)asoc->c.auth_chunks);
}

/* SCTP-AUTH: Section 6.2:
 *    The sender MUST calculate the MAC as described in RFC2104 [2] using
 *    the hash function H as described by the MAC Identifier and the shared
 *    association key K based on the endpoint pair shared key described by
 *    the shared key identifier.  The 'data' used for the computation of
 *    the AUTH-chunk is given by the AUTH chunk with its HMAC field set to
 *    zero (as shown in Figure 6) followed by all chunks that are placed
 *    after the AUTH chunk in the SCTP packet.
 */
void sctp_auth_calculate_hmac(const struct sctp_association *asoc,
                  struct sk_buff *skb,
                  struct sctp_auth_chunk *auth,
                  gfp_t gfp)
{
    struct scatterlist sg;
    struct hash_desc desc;
    struct sctp_auth_bytes *asoc_key;
    __u16 key_id, hmac_id;
    __u8 *digest;
    unsigned char *end;
    int free_key = 0;

    /* Extract the info we need:
     * - hmac id
     * - key id
     */
    key_id = ntohs(auth->auth_hdr.shkey_id);
    hmac_id = ntohs(auth->auth_hdr.hmac_id);

    if (key_id == asoc->active_key_id)
        asoc_key = asoc->asoc_shared_key;
    else {
        struct sctp_shared_key *ep_key;

        ep_key = sctp_auth_get_shkey(asoc, key_id);
        if (!ep_key)
            return;

        asoc_key = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
        if (!asoc_key)
            return;

        free_key = 1;
    }

    /* set up scatter list */
    end = skb_tail_pointer(skb);
    sg_init_one(&sg, auth, end - (unsigned char *)auth);

    desc.tfm = asoc->ep->auth_hmacs[hmac_id];
    desc.flags = 0;

    digest = auth->auth_hdr.hmac;
    if (crypto_hash_setkey(desc.tfm, &asoc_key->data[0], asoc_key->len))
        goto free;

    crypto_hash_digest(&desc, &sg, sg.length, digest);

free:
    if (free_key)
        sctp_auth_key_put(asoc_key);
}

/* API Helpers */

/* Add a chunk to the endpoint authenticated chunk list */
int sctp_auth_ep_add_chunkid(struct sctp_endpoint *ep, __u8 chunk_id)
{
    struct sctp_chunks_param *p = ep->auth_chunk_list;
    __u16 nchunks;
    __u16 param_len;

    /* If this chunk is already specified, we are done */
    if (__sctp_auth_cid(chunk_id, p))
        return 0;

    /* Check if we can add this chunk to the array */
    param_len = ntohs(p->param_hdr.length);
    nchunks = param_len - sizeof(sctp_paramhdr_t);
    if (nchunks == SCTP_NUM_CHUNK_TYPES)
        return -EINVAL;

    p->chunks[nchunks] = chunk_id;
    p->param_hdr.length = htons(param_len + 1);
    return 0;
}

/* Add hmac identifires to the endpoint list of supported hmac ids */
int sctp_auth_ep_set_hmacs(struct sctp_endpoint *ep,
               struct sctp_hmacalgo *hmacs)
{
    int has_sha1 = 0;
    __u16 id;
    int i;

    /* Scan the list looking for unsupported id.  Also make sure that
     * SHA1 is specified.
     */
    for (i = 0; i < hmacs->shmac_num_idents; i++) {
        id = hmacs->shmac_idents[i];

        if (id > SCTP_AUTH_HMAC_ID_MAX)
            return -EOPNOTSUPP;

        if (SCTP_AUTH_HMAC_ID_SHA1 == id)
            has_sha1 = 1;

        if (!sctp_hmac_list[id].hmac_name)
            return -EOPNOTSUPP;
    }

    if (!has_sha1)
        return -EINVAL;

    memcpy(ep->auth_hmacs_list->hmac_ids, &hmacs->shmac_idents[0],
        hmacs->shmac_num_idents * sizeof(__u16));
    ep->auth_hmacs_list->param_hdr.length = htons(sizeof(sctp_paramhdr_t) +
                hmacs->shmac_num_idents * sizeof(__u16));
    return 0;
}

/* Set a new shared key on either endpoint or association.  If the
 * the key with a same ID already exists, replace the key (remove the
 * old key and add a new one).
 */
int sctp_auth_set_key(struct sctp_endpoint *ep,
              struct sctp_association *asoc,
              struct sctp_authkey *auth_key)
{
    struct sctp_shared_key *cur_key = NULL;
    struct sctp_auth_bytes *key;
    struct list_head *sh_keys;
    int replace = 0;

    /* Try to find the given key id to see if
     * we are doing a replace, or adding a new key
     */
    if (asoc)
        sh_keys = &asoc->endpoint_shared_keys;
    else
        sh_keys = &ep->endpoint_shared_keys;

    key_for_each(cur_key, sh_keys) {
        if (cur_key->key_id == auth_key->sca_keynumber) {
            replace = 1;
            break;
        }
    }

    /* If we are not replacing a key id, we need to allocate
     * a shared key.
     */
    if (!replace) {
        cur_key = sctp_auth_shkey_create(auth_key->sca_keynumber,
                         GFP_KERNEL);
        if (!cur_key)
            return -ENOMEM;
    }

    /* Create a new key data based on the info passed in */
    key = sctp_auth_create_key(auth_key->sca_keylength, GFP_KERNEL);
    if (!key)
        goto nomem;

    memcpy(key->data, &auth_key->sca_key[0], auth_key->sca_keylength);

    /* If we are replacing, remove the old keys data from the
     * key id.  If we are adding new key id, add it to the
     * list.
     */
    if (replace)
        sctp_auth_key_put(cur_key->key);
    else
        list_add(&cur_key->key_list, sh_keys);

    cur_key->key = key;
    sctp_auth_key_hold(key);

    return 0;
nomem:
    if (!replace)
        sctp_auth_shkey_free(cur_key);

    return -ENOMEM;
}

int sctp_auth_set_active_key(struct sctp_endpoint *ep,
                 struct sctp_association *asoc,
                 __u16  key_id)
{
    struct sctp_shared_key *key;
    struct list_head *sh_keys;
    int found = 0;

    /* The key identifier MUST correst to an existing key */
    if (asoc)
        sh_keys = &asoc->endpoint_shared_keys;
    else
        sh_keys = &ep->endpoint_shared_keys;

    key_for_each(key, sh_keys) {
        if (key->key_id == key_id) {
            found = 1;
            break;
        }
    }

    if (!found)
        return -EINVAL;

    if (asoc) {
        asoc->active_key_id = key_id;
        sctp_auth_asoc_init_active_key(asoc, GFP_KERNEL);
    } else
        ep->active_key_id = key_id;

    return 0;
}

int sctp_auth_del_key_id(struct sctp_endpoint *ep,
             struct sctp_association *asoc,
             __u16  key_id)
{
    struct sctp_shared_key *key;
    struct list_head *sh_keys;
    int found = 0;

    /* The key identifier MUST NOT be the current active key
     * The key identifier MUST correst to an existing key
     */
    if (asoc) {
        if (asoc->active_key_id == key_id)
            return -EINVAL;

        sh_keys = &asoc->endpoint_shared_keys;
    } else {
        if (ep->active_key_id == key_id)
            return -EINVAL;

        sh_keys = &ep->endpoint_shared_keys;
    }

    key_for_each(key, sh_keys) {
        if (key->key_id == key_id) {
            found = 1;
            break;
        }
    }

    if (!found)
        return -EINVAL;

    /* Delete the shared key */
    list_del_init(&key->key_list);
    sctp_auth_shkey_free(key);

    return 0;
}