[mirror_zfs-debian.git] / module / icp / core / kcf_mech_tabs.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/zfs_context.h>
#include <sys/crypto/common.h>
#include <sys/crypto/api.h>
#include <sys/crypto/impl.h>
#include <sys/modhash.h>

/* Cryptographic mechanisms tables and their access functions */

/*
 * Internal numbers assigned to mechanisms are coded as follows:
 *
 * +----------------+----------------+
 * | mech. class    | mech. index    |
 * <--- 32-bits --->+<--- 32-bits --->
 *
 * the mech_class identifies the table the mechanism belongs to.
 * mech_index  is the index for that mechanism in the table.
 * A mechanism belongs to exactly 1 table.
 * The tables are:
 * . digest_mechs_tab[] for the msg digest mechs.
 * . cipher_mechs_tab[] for encrypt/decrypt and wrap/unwrap mechs.
 * . mac_mechs_tab[] for MAC mechs.
 * . sign_mechs_tab[] for sign & verify mechs.
 * . keyops_mechs_tab[] for key/key pair generation, and key derivation.
 * . misc_mechs_tab[] for mechs that don't belong to any of the above.
 *
 * There are no holes in the tables.
 */

/*
 * Locking conventions:
 * --------------------
 * A global mutex, kcf_mech_tabs_lock, serializes writes to the
 * mechanism table via kcf_create_mech_entry().
 *
 * A mutex is associated with every entry of the tables.
 * The mutex is acquired whenever the entry is accessed for
 * 1) retrieving the mech_id (comparing the mech name)
 * 2) finding a provider for an xxx_init() or atomic operation.
 * 3) altering the mechs entry to add or remove a provider.
 *
 * In 2), after a provider is chosen, its prov_desc is held and the
 * entry's mutex must be dropped. The provider's working function (SPI) is
 * called outside the mech_entry's mutex.
 *
 * The number of providers for a particular mechanism is not expected to be
 * long enough to justify the cost of using rwlocks, so the per-mechanism
 * entry mutex won't be very *hot*.
 *
 * When both kcf_mech_tabs_lock and a mech_entry mutex need to be held,
 * kcf_mech_tabs_lock must always be acquired first.
 *
 */

                /* Mechanisms tables */


/* RFE 4687834 Will deal with the extensibility of these tables later */

kcf_mech_entry_t kcf_digest_mechs_tab[KCF_MAXDIGEST];
kcf_mech_entry_t kcf_cipher_mechs_tab[KCF_MAXCIPHER];
kcf_mech_entry_t kcf_mac_mechs_tab[KCF_MAXMAC];
kcf_mech_entry_t kcf_sign_mechs_tab[KCF_MAXSIGN];
kcf_mech_entry_t kcf_keyops_mechs_tab[KCF_MAXKEYOPS];
kcf_mech_entry_t kcf_misc_mechs_tab[KCF_MAXMISC];

kcf_mech_entry_tab_t kcf_mech_tabs_tab[KCF_LAST_OPSCLASS + 1] = {
        {0, NULL},                              /* No class zero */
        {KCF_MAXDIGEST, kcf_digest_mechs_tab},
        {KCF_MAXCIPHER, kcf_cipher_mechs_tab},
        {KCF_MAXMAC, kcf_mac_mechs_tab},
        {KCF_MAXSIGN, kcf_sign_mechs_tab},
        {KCF_MAXKEYOPS, kcf_keyops_mechs_tab},
        {KCF_MAXMISC, kcf_misc_mechs_tab}
};

/*
 * Per-algorithm internal thresholds for the minimum input size of before
 * offloading to hardware provider.
 * Dispatching a crypto operation  to a hardware provider entails paying the
 * cost of an additional context switch.  Measurments with Sun Accelerator 4000
 * shows that 512-byte jobs or smaller are better handled in software.
 * There is room for refinement here.
 *
 */
int kcf_md5_threshold = 512;
int kcf_sha1_threshold = 512;
int kcf_des_threshold = 512;
int kcf_des3_threshold = 512;
int kcf_aes_threshold = 512;
int kcf_bf_threshold = 512;
int kcf_rc4_threshold = 512;

kmutex_t kcf_mech_tabs_lock;
static uint32_t kcf_gen_swprov = 0;

int kcf_mech_hash_size = 256;
mod_hash_t *kcf_mech_hash;      /* mech name to id hash */

static crypto_mech_type_t
kcf_mech_hash_find(char *mechname)
{
        mod_hash_val_t hv;
        crypto_mech_type_t mt;

        mt = CRYPTO_MECH_INVALID;
        if (mod_hash_find(kcf_mech_hash, (mod_hash_key_t)mechname, &hv) == 0) {
                mt = *(crypto_mech_type_t *)hv;
                ASSERT(mt != CRYPTO_MECH_INVALID);
        }

        return (mt);
}

void
kcf_destroy_mech_tabs(void)
{
        int i, max;
        kcf_ops_class_t class;
        kcf_mech_entry_t *me_tab;

        if (kcf_mech_hash)
                mod_hash_destroy_hash(kcf_mech_hash);

        mutex_destroy(&kcf_mech_tabs_lock);

        for (class = KCF_FIRST_OPSCLASS; class <= KCF_LAST_OPSCLASS; class++) {
                max = kcf_mech_tabs_tab[class].met_size;
                me_tab = kcf_mech_tabs_tab[class].met_tab;
                for (i = 0; i < max; i++)
                        mutex_destroy(&(me_tab[i].me_mutex));
        }
}

/*
 * kcf_init_mech_tabs()
 *
 * Called by the misc/kcf's _init() routine to initialize the tables
 * of mech_entry's.
 */
void
kcf_init_mech_tabs(void)
{
        int i, max;
        kcf_ops_class_t class;
        kcf_mech_entry_t *me_tab;

        /* Initializes the mutex locks. */

        mutex_init(&kcf_mech_tabs_lock, NULL, MUTEX_DEFAULT, NULL);

        /* Then the pre-defined mechanism entries */

        /* Two digests */
        (void) strncpy(kcf_digest_mechs_tab[0].me_name, SUN_CKM_MD5,
            CRYPTO_MAX_MECH_NAME);
        kcf_digest_mechs_tab[0].me_threshold = kcf_md5_threshold;

        (void) strncpy(kcf_digest_mechs_tab[1].me_name, SUN_CKM_SHA1,
            CRYPTO_MAX_MECH_NAME);
        kcf_digest_mechs_tab[1].me_threshold = kcf_sha1_threshold;

        /* The symmetric ciphers in various modes */
        (void) strncpy(kcf_cipher_mechs_tab[0].me_name, SUN_CKM_DES_CBC,
            CRYPTO_MAX_MECH_NAME);
        kcf_cipher_mechs_tab[0].me_threshold = kcf_des_threshold;

        (void) strncpy(kcf_cipher_mechs_tab[1].me_name, SUN_CKM_DES3_CBC,
            CRYPTO_MAX_MECH_NAME);
        kcf_cipher_mechs_tab[1].me_threshold = kcf_des3_threshold;

        (void) strncpy(kcf_cipher_mechs_tab[2].me_name, SUN_CKM_DES_ECB,
            CRYPTO_MAX_MECH_NAME);
        kcf_cipher_mechs_tab[2].me_threshold = kcf_des_threshold;

        (void) strncpy(kcf_cipher_mechs_tab[3].me_name, SUN_CKM_DES3_ECB,
            CRYPTO_MAX_MECH_NAME);
        kcf_cipher_mechs_tab[3].me_threshold = kcf_des3_threshold;

        (void) strncpy(kcf_cipher_mechs_tab[4].me_name, SUN_CKM_BLOWFISH_CBC,
            CRYPTO_MAX_MECH_NAME);
        kcf_cipher_mechs_tab[4].me_threshold = kcf_bf_threshold;

        (void) strncpy(kcf_cipher_mechs_tab[5].me_name, SUN_CKM_BLOWFISH_ECB,
            CRYPTO_MAX_MECH_NAME);
        kcf_cipher_mechs_tab[5].me_threshold = kcf_bf_threshold;

        (void) strncpy(kcf_cipher_mechs_tab[6].me_name, SUN_CKM_AES_CBC,
            CRYPTO_MAX_MECH_NAME);
        kcf_cipher_mechs_tab[6].me_threshold = kcf_aes_threshold;

        (void) strncpy(kcf_cipher_mechs_tab[7].me_name, SUN_CKM_AES_ECB,
            CRYPTO_MAX_MECH_NAME);
        kcf_cipher_mechs_tab[7].me_threshold = kcf_aes_threshold;

        (void) strncpy(kcf_cipher_mechs_tab[8].me_name, SUN_CKM_RC4,
            CRYPTO_MAX_MECH_NAME);
        kcf_cipher_mechs_tab[8].me_threshold = kcf_rc4_threshold;


        /* 4 HMACs */
        (void) strncpy(kcf_mac_mechs_tab[0].me_name, SUN_CKM_MD5_HMAC,
            CRYPTO_MAX_MECH_NAME);
        kcf_mac_mechs_tab[0].me_threshold = kcf_md5_threshold;

        (void) strncpy(kcf_mac_mechs_tab[1].me_name, SUN_CKM_MD5_HMAC_GENERAL,
            CRYPTO_MAX_MECH_NAME);
        kcf_mac_mechs_tab[1].me_threshold = kcf_md5_threshold;

        (void) strncpy(kcf_mac_mechs_tab[2].me_name, SUN_CKM_SHA1_HMAC,
            CRYPTO_MAX_MECH_NAME);
        kcf_mac_mechs_tab[2].me_threshold = kcf_sha1_threshold;

        (void) strncpy(kcf_mac_mechs_tab[3].me_name, SUN_CKM_SHA1_HMAC_GENERAL,
            CRYPTO_MAX_MECH_NAME);
        kcf_mac_mechs_tab[3].me_threshold = kcf_sha1_threshold;


        /* 1 random number generation pseudo mechanism */
        (void) strncpy(kcf_misc_mechs_tab[0].me_name, SUN_RANDOM,
            CRYPTO_MAX_MECH_NAME);

        kcf_mech_hash = mod_hash_create_strhash_nodtr("kcf mech2id hash",
            kcf_mech_hash_size, mod_hash_null_valdtor);

        for (class = KCF_FIRST_OPSCLASS; class <= KCF_LAST_OPSCLASS; class++) {
                max = kcf_mech_tabs_tab[class].met_size;
                me_tab = kcf_mech_tabs_tab[class].met_tab;
                for (i = 0; i < max; i++) {
                        mutex_init(&(me_tab[i].me_mutex), NULL,
                            MUTEX_DEFAULT, NULL);
                        if (me_tab[i].me_name[0] != 0) {
                                me_tab[i].me_mechid = KCF_MECHID(class, i);
                                (void) mod_hash_insert(kcf_mech_hash,
                                    (mod_hash_key_t)me_tab[i].me_name,
                                    (mod_hash_val_t)&(me_tab[i].me_mechid));
                        }
                }
        }
}

/*
 * kcf_create_mech_entry()
 *
 * Arguments:
 *      . The class of mechanism.
 *      . the name of the new mechanism.
 *
 * Description:
 *      Creates a new mech_entry for a mechanism not yet known to the
 *      framework.
 *      This routine is called by kcf_add_mech_provider, which is
 *      in turn invoked for each mechanism supported by a provider.
 *      The'class' argument depends on the crypto_func_group_t bitmask
 *      in the registering provider's mech_info struct for this mechanism.
 *      When there is ambiguity in the mapping between the crypto_func_group_t
 *      and a class (dual ops, ...) the KCF_MISC_CLASS should be used.
 *
 * Context:
 *      User context only.
 *
 * Returns:
 *      KCF_INVALID_MECH_CLASS or KCF_INVALID_MECH_NAME if the class or
 *      the mechname is bogus.
 *      KCF_MECH_TAB_FULL when there is no room left in the mech. tabs.
 *      KCF_SUCCESS otherwise.
 */
static int
kcf_create_mech_entry(kcf_ops_class_t class, char *mechname)
{
        crypto_mech_type_t mt;
        kcf_mech_entry_t *me_tab;
        int i = 0, size;

        if ((class < KCF_FIRST_OPSCLASS) || (class > KCF_LAST_OPSCLASS))
                return (KCF_INVALID_MECH_CLASS);

        if ((mechname == NULL) || (mechname[0] == 0))
                return (KCF_INVALID_MECH_NAME);
        /*
         * First check if the mechanism is already in one of the tables.
         * The mech_entry could be in another class.
         */
        mutex_enter(&kcf_mech_tabs_lock);
        mt = kcf_mech_hash_find(mechname);
        if (mt != CRYPTO_MECH_INVALID) {
                /* Nothing to do, regardless the suggested class. */
                mutex_exit(&kcf_mech_tabs_lock);
                return (KCF_SUCCESS);
        }
        /* Now take the next unused mech entry in the class's tab */
        me_tab = kcf_mech_tabs_tab[class].met_tab;
        size = kcf_mech_tabs_tab[class].met_size;

        while (i < size) {
                mutex_enter(&(me_tab[i].me_mutex));
                if (me_tab[i].me_name[0] == 0) {
                        /* Found an empty spot */
                        (void) strncpy(me_tab[i].me_name, mechname,
                            CRYPTO_MAX_MECH_NAME);
                        me_tab[i].me_name[CRYPTO_MAX_MECH_NAME-1] = '\0';
                        me_tab[i].me_mechid = KCF_MECHID(class, i);
                        /*
                         * No a-priori information about the new mechanism, so
                         * the threshold is set to zero.
                         */
                        me_tab[i].me_threshold = 0;

                        mutex_exit(&(me_tab[i].me_mutex));
                        /* Add the new mechanism to the hash table */
                        (void) mod_hash_insert(kcf_mech_hash,
                            (mod_hash_key_t)me_tab[i].me_name,
                            (mod_hash_val_t)&(me_tab[i].me_mechid));
                        break;
                }
                mutex_exit(&(me_tab[i].me_mutex));
                i++;
        }

        mutex_exit(&kcf_mech_tabs_lock);

        if (i == size) {
                return (KCF_MECH_TAB_FULL);
        }

        return (KCF_SUCCESS);
}

/*
 * kcf_add_mech_provider()
 *
 * Arguments:
 *      . An index in to  the provider mechanism array
 *      . A pointer to the provider descriptor
 *      . A storage for the kcf_prov_mech_desc_t the entry was added at.
 *
 * Description:
 *      Adds  a new provider of a mechanism to the mechanism's mech_entry
 *      chain.
 *
 * Context:
 *      User context only.
 *
 * Returns
 *      KCF_SUCCESS on success
 *      KCF_MECH_TAB_FULL otherwise.
 */
int
kcf_add_mech_provider(short mech_indx,
    kcf_provider_desc_t *prov_desc, kcf_prov_mech_desc_t **pmdpp)
{
        int error;
        kcf_mech_entry_t *mech_entry = NULL;
        crypto_mech_info_t *mech_info;
        crypto_mech_type_t kcf_mech_type, mt;
        kcf_prov_mech_desc_t *prov_mech, *prov_mech2;
        crypto_func_group_t simple_fg_mask, dual_fg_mask;
        crypto_mech_info_t *dmi;
        crypto_mech_info_list_t *mil, *mil2;
        kcf_mech_entry_t *me;
        int i;

        ASSERT(prov_desc->pd_prov_type != CRYPTO_LOGICAL_PROVIDER);

        mech_info = &prov_desc->pd_mechanisms[mech_indx];

        /*
         * A mechanism belongs to exactly one mechanism table.
         * Find the class corresponding to the function group flag of
         * the mechanism.
         */
        kcf_mech_type = kcf_mech_hash_find(mech_info->cm_mech_name);
        if (kcf_mech_type == CRYPTO_MECH_INVALID) {
                crypto_func_group_t fg = mech_info->cm_func_group_mask;
                kcf_ops_class_t class;

                if (fg & CRYPTO_FG_DIGEST || fg & CRYPTO_FG_DIGEST_ATOMIC)
                        class = KCF_DIGEST_CLASS;
                else if (fg & CRYPTO_FG_ENCRYPT || fg & CRYPTO_FG_DECRYPT ||
                    fg & CRYPTO_FG_ENCRYPT_ATOMIC ||
                    fg & CRYPTO_FG_DECRYPT_ATOMIC)
                        class = KCF_CIPHER_CLASS;
                else if (fg & CRYPTO_FG_MAC || fg & CRYPTO_FG_MAC_ATOMIC)
                        class = KCF_MAC_CLASS;
                else if (fg & CRYPTO_FG_SIGN || fg & CRYPTO_FG_VERIFY ||
                    fg & CRYPTO_FG_SIGN_ATOMIC ||
                    fg & CRYPTO_FG_VERIFY_ATOMIC ||
                    fg & CRYPTO_FG_SIGN_RECOVER ||
                    fg & CRYPTO_FG_VERIFY_RECOVER)
                        class = KCF_SIGN_CLASS;
                else if (fg & CRYPTO_FG_GENERATE ||
                    fg & CRYPTO_FG_GENERATE_KEY_PAIR ||
                    fg & CRYPTO_FG_WRAP || fg & CRYPTO_FG_UNWRAP ||
                    fg & CRYPTO_FG_DERIVE)
                        class = KCF_KEYOPS_CLASS;
                else
                        class = KCF_MISC_CLASS;

                /*
                 * Attempt to create a new mech_entry for the specified
                 * mechanism. kcf_create_mech_entry() can handle the case
                 * where such an entry already exists.
                 */
                if ((error = kcf_create_mech_entry(class,
                    mech_info->cm_mech_name)) != KCF_SUCCESS) {
                        return (error);
                }
                /* get the KCF mech type that was assigned to the mechanism */
                kcf_mech_type = kcf_mech_hash_find(mech_info->cm_mech_name);
                ASSERT(kcf_mech_type != CRYPTO_MECH_INVALID);
        }

        error = kcf_get_mech_entry(kcf_mech_type, &mech_entry);
        ASSERT(error == KCF_SUCCESS);

        /* allocate and initialize new kcf_prov_mech_desc */
        prov_mech = kmem_zalloc(sizeof (kcf_prov_mech_desc_t), KM_SLEEP);
        bcopy(mech_info, &prov_mech->pm_mech_info, sizeof (crypto_mech_info_t));
        prov_mech->pm_prov_desc = prov_desc;
        prov_desc->pd_mech_indx[KCF_MECH2CLASS(kcf_mech_type)]
            [KCF_MECH2INDEX(kcf_mech_type)] = mech_indx;

        KCF_PROV_REFHOLD(prov_desc);
        KCF_PROV_IREFHOLD(prov_desc);

        dual_fg_mask = mech_info->cm_func_group_mask & CRYPTO_FG_DUAL_MASK;

        if (dual_fg_mask == ((crypto_func_group_t)0))
                goto add_entry;

        simple_fg_mask = (mech_info->cm_func_group_mask &
            CRYPTO_FG_SIMPLEOP_MASK) | CRYPTO_FG_RANDOM;

        for (i = 0; i < prov_desc->pd_mech_list_count; i++) {
                dmi = &prov_desc->pd_mechanisms[i];

                /* skip self */
                if (dmi->cm_mech_number == mech_info->cm_mech_number)
                        continue;

                /* skip if not a dual operation mechanism */
                if (!(dmi->cm_func_group_mask & dual_fg_mask) ||
                    (dmi->cm_func_group_mask & simple_fg_mask))
                        continue;

                mt = kcf_mech_hash_find(dmi->cm_mech_name);
                if (mt == CRYPTO_MECH_INVALID)
                        continue;

                if (kcf_get_mech_entry(mt, &me) != KCF_SUCCESS)
                        continue;

                mil = kmem_zalloc(sizeof (*mil), KM_SLEEP);
                mil2 = kmem_zalloc(sizeof (*mil2), KM_SLEEP);

                /*
                 * Ignore hard-coded entries in the mech table
                 * if the provider hasn't registered.
                 */
                mutex_enter(&me->me_mutex);
                if (me->me_hw_prov_chain == NULL && me->me_sw_prov == NULL) {
                        mutex_exit(&me->me_mutex);
                        kmem_free(mil, sizeof (*mil));
                        kmem_free(mil2, sizeof (*mil2));
                        continue;
                }

                /*
                 * Add other dual mechanisms that have registered
                 * with the framework to this mechanism's
                 * cross-reference list.
                 */
                mil->ml_mech_info = *dmi; /* struct assignment */
                mil->ml_kcf_mechid = mt;

                /* add to head of list */
                mil->ml_next = prov_mech->pm_mi_list;
                prov_mech->pm_mi_list = mil;

                if (prov_desc->pd_prov_type == CRYPTO_HW_PROVIDER)
                        prov_mech2 = me->me_hw_prov_chain;
                else
                        prov_mech2 = me->me_sw_prov;

                if (prov_mech2 == NULL) {
                        kmem_free(mil2, sizeof (*mil2));
                        mutex_exit(&me->me_mutex);
                        continue;
                }

                /*
                 * Update all other cross-reference lists by
                 * adding this new mechanism.
                 */
                while (prov_mech2 != NULL) {
                        if (prov_mech2->pm_prov_desc == prov_desc) {
                                /* struct assignment */
                                mil2->ml_mech_info = *mech_info;
                                mil2->ml_kcf_mechid = kcf_mech_type;

                                /* add to head of list */
                                mil2->ml_next = prov_mech2->pm_mi_list;
                                prov_mech2->pm_mi_list = mil2;
                                break;
                        }
                        prov_mech2 = prov_mech2->pm_next;
                }
                if (prov_mech2 == NULL)
                        kmem_free(mil2, sizeof (*mil2));

                mutex_exit(&me->me_mutex);
        }

add_entry:
        /*
         * Add new kcf_prov_mech_desc at the front of HW providers
         * chain.
         */
        switch (prov_desc->pd_prov_type) {

        case CRYPTO_HW_PROVIDER:
                mutex_enter(&mech_entry->me_mutex);
                prov_mech->pm_me = mech_entry;
                prov_mech->pm_next = mech_entry->me_hw_prov_chain;
                mech_entry->me_hw_prov_chain = prov_mech;
                mech_entry->me_num_hwprov++;
                mutex_exit(&mech_entry->me_mutex);
                break;

        case CRYPTO_SW_PROVIDER:
                mutex_enter(&mech_entry->me_mutex);
                if (mech_entry->me_sw_prov != NULL) {
                        /*
                         * There is already a SW provider for this mechanism.
                         * Since we allow only one SW provider per mechanism,
                         * report this condition.
                         */
                        cmn_err(CE_WARN, "The cryptographic software provider "
                            "\"%s\" will not be used for %s. The provider "
                            "\"%s\" will be used for this mechanism "
                            "instead.", prov_desc->pd_description,
                            mech_info->cm_mech_name,
                            mech_entry->me_sw_prov->pm_prov_desc->
                            pd_description);
                        KCF_PROV_REFRELE(prov_desc);
                        kmem_free(prov_mech, sizeof (kcf_prov_mech_desc_t));
                        prov_mech = NULL;
                } else {
                        /*
                         * Set the provider as the software provider for
                         * this mechanism.
                         */
                        mech_entry->me_sw_prov = prov_mech;

                        /* We'll wrap around after 4 billion registrations! */
                        mech_entry->me_gen_swprov = kcf_gen_swprov++;
                }
                mutex_exit(&mech_entry->me_mutex);
                break;
        default:
                break;
        }

        *pmdpp = prov_mech;

        return (KCF_SUCCESS);
}

/*
 * kcf_remove_mech_provider()
 *
 * Arguments:
 *      . mech_name: the name of the mechanism.
 *      . prov_desc: The provider descriptor
 *
 * Description:
 *      Removes a provider from chain of provider descriptors.
 *      The provider is made unavailable to kernel consumers for the specified
 *      mechanism.
 *
 * Context:
 *      User context only.
 */
void
kcf_remove_mech_provider(char *mech_name, kcf_provider_desc_t *prov_desc)
{
        crypto_mech_type_t mech_type;
        kcf_prov_mech_desc_t *prov_mech = NULL, *prov_chain;
        kcf_prov_mech_desc_t **prev_entry_next;
        kcf_mech_entry_t *mech_entry;
        crypto_mech_info_list_t *mil, *mil2, *next, **prev_next;

        ASSERT(prov_desc->pd_prov_type != CRYPTO_LOGICAL_PROVIDER);

        /* get the KCF mech type that was assigned to the mechanism */
        if ((mech_type = kcf_mech_hash_find(mech_name)) ==
            CRYPTO_MECH_INVALID) {
                /*
                 * Provider was not allowed for this mech due to policy or
                 * configuration.
                 */
                return;
        }

        /* get a ptr to the mech_entry that was created */
        if (kcf_get_mech_entry(mech_type, &mech_entry) != KCF_SUCCESS) {
                /*
                 * Provider was not allowed for this mech due to policy or
                 * configuration.
                 */
                return;
        }

        mutex_enter(&mech_entry->me_mutex);

        switch (prov_desc->pd_prov_type) {

        case CRYPTO_HW_PROVIDER:
                /* find the provider in the mech_entry chain */
                prev_entry_next = &mech_entry->me_hw_prov_chain;
                prov_mech = mech_entry->me_hw_prov_chain;
                while (prov_mech != NULL &&
                    prov_mech->pm_prov_desc != prov_desc) {
                        prev_entry_next = &prov_mech->pm_next;
                        prov_mech = prov_mech->pm_next;
                }

                if (prov_mech == NULL) {
                        /* entry not found, simply return */
                        mutex_exit(&mech_entry->me_mutex);
                        return;
                }

                /* remove provider entry from mech_entry chain */
                *prev_entry_next = prov_mech->pm_next;
                ASSERT(mech_entry->me_num_hwprov > 0);
                mech_entry->me_num_hwprov--;
                break;

        case CRYPTO_SW_PROVIDER:
                if (mech_entry->me_sw_prov == NULL ||
                    mech_entry->me_sw_prov->pm_prov_desc != prov_desc) {
                        /* not the software provider for this mechanism */
                        mutex_exit(&mech_entry->me_mutex);
                        return;
                }
                prov_mech = mech_entry->me_sw_prov;
                mech_entry->me_sw_prov = NULL;
                break;
        default:
                /* unexpected crypto_provider_type_t */
                mutex_exit(&mech_entry->me_mutex);
                return;
        }

        mutex_exit(&mech_entry->me_mutex);

        /* Free the dual ops cross-reference lists  */
        mil = prov_mech->pm_mi_list;
        while (mil != NULL) {
                next = mil->ml_next;
                if (kcf_get_mech_entry(mil->ml_kcf_mechid,
                    &mech_entry) != KCF_SUCCESS) {
                        mil = next;
                        continue;
                }

                mutex_enter(&mech_entry->me_mutex);
                if (prov_desc->pd_prov_type == CRYPTO_HW_PROVIDER)
                        prov_chain = mech_entry->me_hw_prov_chain;
                else
                        prov_chain = mech_entry->me_sw_prov;

                while (prov_chain != NULL) {
                        if (prov_chain->pm_prov_desc == prov_desc) {
                                prev_next = &prov_chain->pm_mi_list;
                                mil2 = prov_chain->pm_mi_list;
                                while (mil2 != NULL &&
                                    mil2->ml_kcf_mechid != mech_type) {
                                        prev_next = &mil2->ml_next;
                                        mil2 = mil2->ml_next;
                                }
                                if (mil2 != NULL) {
                                        *prev_next = mil2->ml_next;
                                        kmem_free(mil2, sizeof (*mil2));
                                }
                                break;
                        }
                        prov_chain = prov_chain->pm_next;
                }

                mutex_exit(&mech_entry->me_mutex);
                kmem_free(mil, sizeof (crypto_mech_info_list_t));
                mil = next;
        }

        /* free entry  */
        KCF_PROV_REFRELE(prov_mech->pm_prov_desc);
        KCF_PROV_IREFRELE(prov_mech->pm_prov_desc);
        kmem_free(prov_mech, sizeof (kcf_prov_mech_desc_t));
}

/*
 * kcf_get_mech_entry()
 *
 * Arguments:
 *      . The framework mechanism type
 *      . Storage for the mechanism entry
 *
 * Description:
 *      Retrieves the mechanism entry for the mech.
 *
 * Context:
 *      User and interrupt contexts.
 *
 * Returns:
 *      KCF_MECHANISM_XXX appropriate error code.
 *      KCF_SUCCESS otherwise.
 */
int
kcf_get_mech_entry(crypto_mech_type_t mech_type, kcf_mech_entry_t **mep)
{
        kcf_ops_class_t         class;
        int                     index;
        kcf_mech_entry_tab_t    *me_tab;

        ASSERT(mep != NULL);

        class = KCF_MECH2CLASS(mech_type);

        if ((class < KCF_FIRST_OPSCLASS) || (class > KCF_LAST_OPSCLASS)) {
                /* the caller won't need to know it's an invalid class */
                return (KCF_INVALID_MECH_NUMBER);
        }

        me_tab = &kcf_mech_tabs_tab[class];
        index = KCF_MECH2INDEX(mech_type);

        if ((index < 0) || (index >= me_tab->met_size)) {
                return (KCF_INVALID_MECH_NUMBER);
        }

        *mep = &((me_tab->met_tab)[index]);

        return (KCF_SUCCESS);
}

/* CURRENTLY UNSUPPORTED: attempting to load the module if it isn't found */
/*
 * Lookup the hash table for an entry that matches the mechname.
 * If there are no hardware or software providers for the mechanism,
 * but there is an unloaded software provider, this routine will attempt
 * to load it.
 *
 * If the MOD_NOAUTOUNLOAD flag is not set, a software provider is
 * in constant danger of being unloaded.  For consumers that call
 * crypto_mech2id() only once, the provider will not be reloaded
 * if it becomes unloaded.  If a provider gets loaded elsewhere
 * without the MOD_NOAUTOUNLOAD flag being set, we set it now.
 */
crypto_mech_type_t
crypto_mech2id_common(char *mechname, boolean_t load_module)
{
        crypto_mech_type_t mt = kcf_mech_hash_find(mechname);
        return (mt);
}