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[zfs.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 https://opensource.org/licenses/CDDL-1.0.
 * 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>

/* 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:
 * . 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 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*.
 *
 */

                /* Mechanisms tables */


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

static kcf_mech_entry_t kcf_cipher_mechs_tab[KCF_MAXCIPHER];
static kcf_mech_entry_t kcf_mac_mechs_tab[KCF_MAXMAC];

const kcf_mech_entry_tab_t kcf_mech_tabs_tab[KCF_LAST_OPSCLASS + 1] = {
        {0, NULL},                              /* No class zero */
        {KCF_MAXCIPHER, kcf_cipher_mechs_tab},
        {KCF_MAXMAC, kcf_mac_mechs_tab},
};

static avl_tree_t kcf_mech_hash;

static int
kcf_mech_hash_compar(const void *lhs, const void *rhs)
{
        const kcf_mech_entry_t *l = lhs, *r = rhs;
        int cmp = strncmp(l->me_name, r->me_name, CRYPTO_MAX_MECH_NAME);
        return ((0 < cmp) - (cmp < 0));
}

void
kcf_destroy_mech_tabs(void)
{
        for (void *cookie = NULL; avl_destroy_nodes(&kcf_mech_hash, &cookie); )
                ;
        avl_destroy(&kcf_mech_hash);
}

/*
 * 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)
{
        avl_create(&kcf_mech_hash, kcf_mech_hash_compar,
            sizeof (kcf_mech_entry_t), offsetof(kcf_mech_entry_t, me_node));
}

/*
 * 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, const char *mechname)
{
        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.
         */
        avl_index_t where = 0;
        kcf_mech_entry_t tmptab;
        strlcpy(tmptab.me_name, mechname, CRYPTO_MAX_MECH_NAME);
        if (avl_find(&kcf_mech_hash, &tmptab, &where) != NULL)
                return (KCF_SUCCESS);
        /* Now take the next unused mech entry in the class's tab */
        kcf_mech_entry_t *me_tab = kcf_mech_tabs_tab[class].met_tab;
        int size = kcf_mech_tabs_tab[class].met_size;

        for (int i = 0; i < size; ++i)
                if (me_tab[i].me_name[0] == 0) {
                        /* Found an empty spot */
                        strlcpy(me_tab[i].me_name, mechname,
                            CRYPTO_MAX_MECH_NAME);
                        me_tab[i].me_mechid = KCF_MECHID(class, i);

                        /* Add the new mechanism to the hash table */
                        avl_insert(&kcf_mech_hash, &me_tab[i], where);
                        return (KCF_SUCCESS);
                }

        return (KCF_MECH_TAB_FULL);
}

/*
 * 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;
        const crypto_mech_info_t *mech_info;
        crypto_mech_type_t kcf_mech_type;
        kcf_prov_mech_desc_t *prov_mech;

        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 = crypto_mech2id(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_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
                        __builtin_unreachable();

                /*
                 * 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 = crypto_mech2id(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);
        memcpy(&prov_mech->pm_mech_info, 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);

        /*
         * Add new kcf_prov_mech_desc at the front of HW providers
         * chain.
         */
        if (mech_entry->me_sw_prov != NULL) {
                /*
                 * There is already a provider for this mechanism.
                 * Since we allow only one provider per mechanism,
                 * report this condition.
                 */
                cmn_err(CE_WARN, "The cryptographic 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 provider for
                 * this mechanism.
                 */
                mech_entry->me_sw_prov = prov_mech;
        }

        *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(const char *mech_name, kcf_provider_desc_t *prov_desc)
{
        crypto_mech_type_t mech_type;
        kcf_prov_mech_desc_t *prov_mech = NULL;
        kcf_mech_entry_t *mech_entry;

        /* get the KCF mech type that was assigned to the mechanism */
        if ((mech_type = crypto_mech2id(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;
        }

        if (mech_entry->me_sw_prov == NULL ||
            mech_entry->me_sw_prov->pm_prov_desc != prov_desc) {
                /* not the provider for this mechanism */
                return;
        }
        prov_mech = mech_entry->me_sw_prov;
        mech_entry->me_sw_prov = NULL;

        /* free entry  */
        KCF_PROV_IREFRELE(prov_mech->pm_prov_desc);
        KCF_PROV_REFRELE(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;
        const 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);
}

/*
 * crypto_mech2id()
 *
 * Arguments:
 *      . mechname: A null-terminated string identifying the mechanism name.
 *
 * Description:
 *      Walks the mechanisms tables, looking for an entry that matches the
 *      mechname. Once it find it, it builds the 64-bit mech_type and returns
 *      it.
 *
 * Context:
 *      Process and interruption.
 *
 * Returns:
 *      The unique mechanism identified by 'mechname', if found.
 *      CRYPTO_MECH_INVALID otherwise.
 */
/*
 * Lookup the hash table for an entry that matches the mechname.
 * If there are no providers for the mechanism,
 * but there is an unloaded provider, this routine will attempt
 * to load it.
 */
crypto_mech_type_t
crypto_mech2id(const char *mechname)
{
        kcf_mech_entry_t tmptab, *found;
        strlcpy(tmptab.me_name, mechname, CRYPTO_MAX_MECH_NAME);

        if ((found = avl_find(&kcf_mech_hash, &tmptab, NULL))) {
                ASSERT(found->me_mechid != CRYPTO_MECH_INVALID);
                return (found->me_mechid);
        }

        return (CRYPTO_MECH_INVALID);
}

#if defined(_KERNEL)
EXPORT_SYMBOL(crypto_mech2id);
#endif