/* 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 <lksctp-developers@lists.sourceforge.net>
 *
 * Or submit a bug report through the following website:
 *    http://www.sf.net/projects/lksctp
 *
 * Written or modified by:
 *   Vlad Yasevich     <vladislav.yasevich@hp.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/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 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 (!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 crypto_hash *tfm = NULL;
        __u16   id;

        /* if the transforms are already allocted, we are done */
        if (!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)
{
        if (!sctp_auth_enable || !asoc || !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)
{
        if (!sctp_auth_enable || !asoc)
                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;
}