openssl/crypto/provider_conf.c

/*
 * Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <string.h>
#include <openssl/trace.h>
#include <openssl/err.h>
#include <openssl/conf.h>
#include <openssl/safestack.h>
#include <openssl/provider.h>
#include "internal/provider.h"
#include "internal/cryptlib.h"
#include "provider_local.h"
#include "crypto/context.h"

DEFINE_STACK_OF(OSSL_PROVIDER)

/* PROVIDER config module */

typedef struct {
    CRYPTO_RWLOCK *lock;
    STACK_OF(OSSL_PROVIDER) *activated_providers;
} PROVIDER_CONF_GLOBAL;

void *ossl_prov_conf_ctx_new(OSSL_LIB_CTX *libctx)
{
    PROVIDER_CONF_GLOBAL *pcgbl = OPENSSL_zalloc(sizeof(*pcgbl));

    if (pcgbl == NULL)
        return NULL;

    pcgbl->lock = CRYPTO_THREAD_lock_new();
    if (pcgbl->lock == NULL) {
        OPENSSL_free(pcgbl);
        return NULL;
    }

    return pcgbl;
}

void ossl_prov_conf_ctx_free(void *vpcgbl)
{
    PROVIDER_CONF_GLOBAL *pcgbl = vpcgbl;

    sk_OSSL_PROVIDER_pop_free(pcgbl->activated_providers,
                              ossl_provider_free);

    OSSL_TRACE(CONF, "Cleaned up providers\n");
    CRYPTO_THREAD_lock_free(pcgbl->lock);
    OPENSSL_free(pcgbl);
}

static const char *skip_dot(const char *name)
{
    const char *p = strchr(name, '.');

    if (p != NULL)
        return p + 1;
    return name;
}

/*
 * Parse the provider params section
 * Returns:
 * 1 for success
 * 0 for non-fatal errors
 * < 0 for fatal errors
 */
static int provider_conf_params_internal(OSSL_PROVIDER *prov,
                                         OSSL_PROVIDER_INFO *provinfo,
                                         const char *name, const char *value,
                                         const CONF *cnf,
                                         STACK_OF(OPENSSL_CSTRING) *visited)
{
    STACK_OF(CONF_VALUE) *sect;
    int ok = 1;
    int rc = 0;

    sect = NCONF_get_section(cnf, value);
    if (sect != NULL) {
        int i;
        char buffer[512];
        size_t buffer_len = 0;

        OSSL_TRACE1(CONF, "Provider params: start section %s\n", value);

        /*
         * Check to see if the provided section value has already
         * been visited.  If it has, then we have a recursive lookup
         * in the configuration which isn't valid.  As such we should error
         * out
         */
        for (i = 0; i < sk_OPENSSL_CSTRING_num(visited); i++) {
            if (sk_OPENSSL_CSTRING_value(visited, i) == value) {
                ERR_raise(ERR_LIB_CONF, CONF_R_RECURSIVE_SECTION_REFERENCE);
                return -1;
            }
        }

        /*
         * We've not visited this node yet, so record it on the stack
         */
        if (!sk_OPENSSL_CSTRING_push(visited, value))
            return -1;

        if (name != NULL) {
            OPENSSL_strlcpy(buffer, name, sizeof(buffer));
            OPENSSL_strlcat(buffer, ".", sizeof(buffer));
            buffer_len = strlen(buffer);
        }

        for (i = 0; i < sk_CONF_VALUE_num(sect); i++) {
            CONF_VALUE *sectconf = sk_CONF_VALUE_value(sect, i);

            if (buffer_len + strlen(sectconf->name) >= sizeof(buffer)) {
                sk_OPENSSL_CSTRING_pop(visited);
                return -1;
            }
            buffer[buffer_len] = '\0';
            OPENSSL_strlcat(buffer, sectconf->name, sizeof(buffer));
            rc = provider_conf_params_internal(prov, provinfo, buffer,
                                               sectconf->value, cnf, visited);
            if (rc < 0) {
                sk_OPENSSL_CSTRING_pop(visited);
                return rc;
            }
        }
        sk_OPENSSL_CSTRING_pop(visited);

        OSSL_TRACE1(CONF, "Provider params: finish section %s\n", value);
    } else {
        OSSL_TRACE2(CONF, "Provider params: %s = %s\n", name, value);
        if (prov != NULL)
            ok = ossl_provider_add_parameter(prov, name, value);
        else
            ok = ossl_provider_info_add_parameter(provinfo, name, value);
    }

    return ok;
}

/*
 * recursively parse the provider configuration section
 * of the config file. 
 * Returns
 * 1 on success
 * 0 on non-fatal error
 * < 0 on fatal errors
 */
static int provider_conf_params(OSSL_PROVIDER *prov,
                                OSSL_PROVIDER_INFO *provinfo,
                                const char *name, const char *value,
                                const CONF *cnf)
{
    int rc;
    STACK_OF(OPENSSL_CSTRING) *visited = sk_OPENSSL_CSTRING_new_null();

    if (visited == NULL)
        return -1;

    rc = provider_conf_params_internal(prov, provinfo, name,
                                       value, cnf, visited);

    sk_OPENSSL_CSTRING_free(visited);

    return rc;
}

static int prov_already_activated(const char *name,
                                  STACK_OF(OSSL_PROVIDER) *activated)
{
    int i, max;

    if (activated == NULL)
        return 0;

    max = sk_OSSL_PROVIDER_num(activated);
    for (i = 0; i < max; i++) {
        OSSL_PROVIDER *tstprov = sk_OSSL_PROVIDER_value(activated, i);

        if (strcmp(OSSL_PROVIDER_get0_name(tstprov), name) == 0) {
            return 1;
        }
    }

    return 0;
}

/*
 * Attempt to activate a provider
 * Returns:
 * 1 on successful activation
 * 0 on failed activation for non-fatal error
 * < 0 on failed activation for fatal errors
 */
static int provider_conf_activate(OSSL_LIB_CTX *libctx, const char *name,
                                  const char *value, const char *path,
                                  int soft, const CONF *cnf)
{
    PROVIDER_CONF_GLOBAL *pcgbl
        = ossl_lib_ctx_get_data(libctx, OSSL_LIB_CTX_PROVIDER_CONF_INDEX);
    OSSL_PROVIDER *prov = NULL, *actual = NULL;
    int ok = 0;

    if (pcgbl == NULL || !CRYPTO_THREAD_write_lock(pcgbl->lock)) {
        ERR_raise(ERR_LIB_CRYPTO, ERR_R_INTERNAL_ERROR);
        return -1;
    }
    if (!prov_already_activated(name, pcgbl->activated_providers)) {
        /*
        * There is an attempt to activate a provider, so we should disable
        * loading of fallbacks. Otherwise a misconfiguration could mean the
        * intended provider does not get loaded. Subsequent fetches could
        * then fallback to the default provider - which may be the wrong
        * thing.
        */
        if (!ossl_provider_disable_fallback_loading(libctx)) {
            CRYPTO_THREAD_unlock(pcgbl->lock);
            ERR_raise(ERR_LIB_CRYPTO, ERR_R_INTERNAL_ERROR);
            return -1;
        }
        prov = ossl_provider_find(libctx, name, 1);
        if (prov == NULL)
            prov = ossl_provider_new(libctx, name, NULL, NULL, 1);
        if (prov == NULL) {
            CRYPTO_THREAD_unlock(pcgbl->lock);
            if (soft)
                ERR_clear_error();
            return (soft == 0) ? -1 : 0;
        }

        if (path != NULL)
            ossl_provider_set_module_path(prov, path);

        ok = provider_conf_params(prov, NULL, NULL, value, cnf);

        if (ok == 1) {
            if (!ossl_provider_activate(prov, 1, 0)) {
                ok = 0;
            } else if (!ossl_provider_add_to_store(prov, &actual, 0)) {
                ossl_provider_deactivate(prov, 1);
                ok = 0;
            } else if (actual != prov
                       && !ossl_provider_activate(actual, 1, 0)) {
                ossl_provider_free(actual);
                ok = 0;
            } else {
                if (pcgbl->activated_providers == NULL)
                    pcgbl->activated_providers = sk_OSSL_PROVIDER_new_null();
                if (pcgbl->activated_providers == NULL
                    || !sk_OSSL_PROVIDER_push(pcgbl->activated_providers,
                                              actual)) {
                    ossl_provider_deactivate(actual, 1);
                    ossl_provider_free(actual);
                    ok = 0;
                } else {
                    ok = 1;
                }
            }
        }

        if (ok <= 0)
            ossl_provider_free(prov);
    }
    CRYPTO_THREAD_unlock(pcgbl->lock);

    return ok;
}

static int provider_conf_load(OSSL_LIB_CTX *libctx, const char *name,
                              const char *value, const CONF *cnf)
{
    int i;
    STACK_OF(CONF_VALUE) *ecmds;
    int soft = 0;
    const char *path = NULL;
    long activate = 0;
    int ok = 0;
    int added = 0;

    name = skip_dot(name);
    OSSL_TRACE1(CONF, "Configuring provider %s\n", name);
    /* Value is a section containing PROVIDER commands */
    ecmds = NCONF_get_section(cnf, value);

    if (!ecmds) {
        ERR_raise_data(ERR_LIB_CRYPTO, CRYPTO_R_PROVIDER_SECTION_ERROR,
                       "section=%s not found", value);
        return 0;
    }

    /* Find the needed data first */
    for (i = 0; i < sk_CONF_VALUE_num(ecmds); i++) {
        CONF_VALUE *ecmd = sk_CONF_VALUE_value(ecmds, i);
        const char *confname = skip_dot(ecmd->name);
        const char *confvalue = ecmd->value;

        OSSL_TRACE2(CONF, "Provider command: %s = %s\n",
                    confname, confvalue);

        /* First handle some special pseudo confs */

        /* Override provider name to use */
        if (strcmp(confname, "identity") == 0)
            name = confvalue;
        else if (strcmp(confname, "soft_load") == 0)
            soft = 1;
        /* Load a dynamic PROVIDER */
        else if (strcmp(confname, "module") == 0)
            path = confvalue;
        else if (strcmp(confname, "activate") == 0)
            activate = 1;
    }

    if (activate) {
        ok = provider_conf_activate(libctx, name, value, path, soft, cnf);
    } else {
        OSSL_PROVIDER_INFO entry;

        memset(&entry, 0, sizeof(entry));
        ok = 1;
        if (name != NULL) {
            entry.name = OPENSSL_strdup(name);
            if (entry.name == NULL)
                ok = 0;
        }
        if (ok && path != NULL) {
            entry.path = OPENSSL_strdup(path);
            if (entry.path == NULL)
                ok = 0;
        }
        if (ok)
            ok = provider_conf_params(NULL, &entry, NULL, value, cnf);
        if (ok >= 1 && (entry.path != NULL || entry.parameters != NULL)) {
            ok = ossl_provider_info_add_to_store(libctx, &entry);
            added = 1;
        }
        if (added == 0)
            ossl_provider_info_clear(&entry);
    }

    /*
     * Provider activation returns a tristate:
     * 1 for successful activation
     * 0 for non-fatal activation failure
     * < 0 for fatal activation failure
     * We return success (1) for activation, (1) for non-fatal activation
     * failure, and (0) for fatal activation failure
     */
    return ok >= 0;
}

static int provider_conf_init(CONF_IMODULE *md, const CONF *cnf)
{
    STACK_OF(CONF_VALUE) *elist;
    CONF_VALUE *cval;
    int i;

    OSSL_TRACE1(CONF, "Loading providers module: section %s\n",
                CONF_imodule_get_value(md));

    /* Value is a section containing PROVIDERs to configure */
    elist = NCONF_get_section(cnf, CONF_imodule_get_value(md));

    if (!elist) {
        ERR_raise(ERR_LIB_CRYPTO, CRYPTO_R_PROVIDER_SECTION_ERROR);
        return 0;
    }

    for (i = 0; i < sk_CONF_VALUE_num(elist); i++) {
        cval = sk_CONF_VALUE_value(elist, i);
        if (!provider_conf_load(NCONF_get0_libctx((CONF *)cnf),
                                cval->name, cval->value, cnf))
            return 0;
    }

    return 1;
}

void ossl_provider_add_conf_module(void)
{
    OSSL_TRACE(CONF, "Adding config module 'providers'\n");
    CONF_module_add("providers", provider_conf_init, NULL);
}