src/auth/passdb.c

/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */

#include "auth-common.h"
#include "array.h"
#include "password-scheme.h"
#include "auth-worker-server.h"
#include "passdb.h"

static ARRAY(struct passdb_module_interface *) passdb_interfaces;
static ARRAY(struct passdb_module *) passdb_modules;

static const struct passdb_module_interface passdb_iface_deinit = {
    .name = "deinit"
};

static struct passdb_module_interface *passdb_interface_find(const char *name)
{
    struct passdb_module_interface *const *ifaces;

    array_foreach(&passdb_interfaces, ifaces) {
        struct passdb_module_interface *iface = *ifaces;

        if (strcmp(iface->name, name) == 0)
            return iface;
    }
    return NULL;
}

void passdb_register_module(struct passdb_module_interface *iface)
{
    struct passdb_module_interface *old_iface;

    old_iface = passdb_interface_find(iface->name);
    if (old_iface != NULL && old_iface->verify_plain == NULL) {
        /* replacing a "support not compiled in" passdb */
        passdb_unregister_module(old_iface);
    } else if (old_iface != NULL) {
        i_panic("passdb_register_module(%s): Already registered",
            iface->name);
    }
    array_append(&passdb_interfaces, &iface, 1);
}

void passdb_unregister_module(struct passdb_module_interface *iface)
{
    struct passdb_module_interface *const *ifaces;
    unsigned int idx;

    array_foreach(&passdb_interfaces, ifaces) {
        if (*ifaces == iface) {
            idx = array_foreach_idx(&passdb_interfaces, ifaces);
            array_delete(&passdb_interfaces, idx, 1);
            return;
        }
    }
    i_panic("passdb_unregister_module(%s): Not registered", iface->name);
}

bool passdb_get_credentials(struct auth_request *auth_request,
                const char *input, const char *input_scheme,
                const unsigned char **credentials_r, size_t *size_r)
{
    const char *wanted_scheme = auth_request->credentials_scheme;
    const char *plaintext, *error;
    int ret;
    struct password_generate_params pwd_gen_params;

    if (auth_request->prefer_plain_credentials &&
        password_scheme_is_alias(input_scheme, "PLAIN")) {
        /* we've a plaintext scheme and we prefer to get it instead
           of converting it to the fallback scheme */
        wanted_scheme = "";
    }

    ret = password_decode(input, input_scheme,
                  credentials_r, size_r, &error);
    if (ret <= 0) {
        if (ret < 0) {
            auth_request_log_error(auth_request, AUTH_SUBSYS_DB,
                "Password data is not valid for scheme %s: %s",
                input_scheme, error);
        } else {
            auth_request_log_error(auth_request, AUTH_SUBSYS_DB,
                "Unknown scheme %s", input_scheme);
        }
        return FALSE;
    }

    if (*wanted_scheme == '\0') {
        /* anything goes. change the credentials_scheme to what we
           actually got, so blocking passdbs work. */
        auth_request->credentials_scheme =
            p_strdup(auth_request->pool, t_strcut(input_scheme, '.'));
        return TRUE;
    }

    if (!password_scheme_is_alias(input_scheme, wanted_scheme)) {
        if (!password_scheme_is_alias(input_scheme, "PLAIN")) {
            const char *error = t_strdup_printf(
                "Requested %s scheme, but we have only %s",
                wanted_scheme, input_scheme);
            if (auth_request->set->debug_passwords) {
                error = t_strdup_printf("%s (input: %s)",
                            error, input);
            }
            auth_request_log_info(auth_request, AUTH_SUBSYS_DB,
                          "%s", error);
            return FALSE;
        }

        /* we can generate anything out of plaintext passwords */
        plaintext = t_strndup(*credentials_r, *size_r);
        i_zero(&pwd_gen_params);
        pwd_gen_params.user = auth_request->original_username;
        if (!auth_request->domain_is_realm &&
            strchr(pwd_gen_params.user, '@') != NULL) {
            /* domain must not be used as realm. add the @realm. */
            pwd_gen_params.user = t_strconcat(pwd_gen_params.user, "@",
                           auth_request->realm, NULL);
        }
        if (auth_request->set->debug_passwords) {
            auth_request_log_debug(auth_request, AUTH_SUBSYS_DB,
                "Generating %s from user '%s', password '%s'",
                wanted_scheme, pwd_gen_params.user, plaintext);
        }
        if (!password_generate(plaintext, &pwd_gen_params,
                       wanted_scheme, credentials_r, size_r)) {
            auth_request_log_error(auth_request, AUTH_SUBSYS_DB,
                "Requested unknown scheme %s", wanted_scheme);
            return FALSE;
        }
    }

    return TRUE;
}

void passdb_handle_credentials(enum passdb_result result,
                   const char *password, const char *scheme,
                   lookup_credentials_callback_t *callback,
                               struct auth_request *auth_request)
{
    const unsigned char *credentials = NULL;
    size_t size = 0;

    if (result != PASSDB_RESULT_OK) {
        callback(result, NULL, 0, auth_request);
        return;
    } else if (auth_fields_exists(auth_request->extra_fields, "noauthenticate")) {
        callback(PASSDB_RESULT_NEXT, NULL, 0, auth_request);
        return;
    }

    if (password != NULL) {
        if (!passdb_get_credentials(auth_request, password, scheme,
                        &credentials, &size))
            result = PASSDB_RESULT_SCHEME_NOT_AVAILABLE;
    } else if (*auth_request->credentials_scheme == '\0') {
        /* We're doing a passdb lookup (not authenticating).
           Pass through a NULL password without an error. */
    } else if (auth_request->delayed_credentials != NULL) {
        /* We already have valid credentials from an earlier
           passdb lookup. auth_request_lookup_credentials_finish()
           will use them. */
    } else {
        auth_request_log_info(auth_request, AUTH_SUBSYS_DB,
            "Requested %s scheme, but we have a NULL password",
            auth_request->credentials_scheme);
        result = PASSDB_RESULT_SCHEME_NOT_AVAILABLE;
    }

    callback(result, credentials, size, auth_request);
}

static struct passdb_module *
passdb_find(const char *driver, const char *args, unsigned int *idx_r)
{
    struct passdb_module *const *passdbs;
    unsigned int i, count;

    passdbs = array_get(&passdb_modules, &count);
    for (i = 0; i < count; i++) {
        if (strcmp(passdbs[i]->iface.name, driver) == 0 &&
            strcmp(passdbs[i]->args, args) == 0) {
            *idx_r = i;
            return passdbs[i];
        }
    }
    return NULL;
}

struct passdb_module *
passdb_preinit(pool_t pool, const struct auth_passdb_settings *set)
{
    static unsigned int auth_passdb_id = 0;
    struct passdb_module_interface *iface;
    struct passdb_module *passdb;
    unsigned int idx;

    iface = passdb_interface_find(set->driver);
    if (iface == NULL || iface->verify_plain == NULL) {
        /* maybe it's a plugin. try to load it. */
        auth_module_load(t_strconcat("authdb_", set->driver, NULL));
        iface = passdb_interface_find(set->driver);
    }
    if (iface == NULL)
        i_fatal("Unknown passdb driver '%s'", set->driver);
    if (iface->verify_plain == NULL) {
        i_fatal("Support not compiled in for passdb driver '%s'",
            set->driver);
    }
    if (iface->preinit == NULL && iface->init == NULL &&
        *set->args != '\0') {
        i_fatal("passdb %s: No args are supported: %s",
            set->driver, set->args);
    }

    passdb = passdb_find(set->driver, set->args, &idx);
    if (passdb != NULL)
        return passdb;

    if (iface->preinit == NULL)
        passdb = p_new(pool, struct passdb_module, 1);
    else
        passdb = iface->preinit(pool, set->args);
    passdb->id = ++auth_passdb_id;
    passdb->iface = *iface;
    passdb->args = p_strdup(pool, set->args);
    if (*set->mechanisms == '\0') {
        passdb->mechanisms = NULL;
    } else if (strcasecmp(set->mechanisms, "none") == 0) {
        passdb->mechanisms = (const char *const[]){NULL};
    } else {
        passdb->mechanisms = (const char* const*)p_strsplit_spaces(pool, set->mechanisms, " ,");
    }

    if (*set->username_filter == '\0') {
        passdb->username_filter = NULL;
    } else {
        passdb->username_filter = (const char* const*)p_strsplit_spaces(pool, set->username_filter, " ,");
    }
    array_append(&passdb_modules, &passdb, 1);
    return passdb;
}

void passdb_init(struct passdb_module *passdb)
{
    if (passdb->iface.init != NULL && passdb->init_refcount == 0)
        passdb->iface.init(passdb);
    passdb->init_refcount++;
}

void passdb_deinit(struct passdb_module *passdb)
{
    unsigned int idx;

    i_assert(passdb->init_refcount > 0);

    if (--passdb->init_refcount > 0)
        return;

    if (passdb_find(passdb->iface.name, passdb->args, &idx) == NULL)
        i_unreached();
    array_delete(&passdb_modules, idx, 1);

    if (passdb->iface.deinit != NULL)
        passdb->iface.deinit(passdb);

    /* make sure passdb isn't accessed again */
    passdb->iface = passdb_iface_deinit;
}

void passdbs_generate_md5(unsigned char md5[STATIC_ARRAY MD5_RESULTLEN])
{
    struct md5_context ctx;
    struct passdb_module *const *passdbs;
    unsigned int i, count;

    md5_init(&ctx);
    passdbs = array_get(&passdb_modules, &count);
    for (i = 0; i < count; i++) {
        md5_update(&ctx, &passdbs[i]->id, sizeof(passdbs[i]->id));
        md5_update(&ctx, passdbs[i]->iface.name,
               strlen(passdbs[i]->iface.name));
        md5_update(&ctx, passdbs[i]->args, strlen(passdbs[i]->args));
    }
    md5_final(&ctx, md5);
}

extern struct passdb_module_interface passdb_passwd;
extern struct passdb_module_interface passdb_bsdauth;
extern struct passdb_module_interface passdb_dict;
#ifdef HAVE_LUA
extern struct passdb_module_interface passdb_lua;
#endif
extern struct passdb_module_interface passdb_shadow;
extern struct passdb_module_interface passdb_passwd_file;
extern struct passdb_module_interface passdb_pam;
extern struct passdb_module_interface passdb_checkpassword;
extern struct passdb_module_interface passdb_vpopmail;
extern struct passdb_module_interface passdb_ldap;
extern struct passdb_module_interface passdb_sql;
extern struct passdb_module_interface passdb_sia;
extern struct passdb_module_interface passdb_static;
extern struct passdb_module_interface passdb_oauth2;

void passdbs_init(void)
{
    i_array_init(&passdb_interfaces, 16);
    i_array_init(&passdb_modules, 16);
    passdb_register_module(&passdb_passwd);
    passdb_register_module(&passdb_bsdauth);
    passdb_register_module(&passdb_dict);
#ifdef HAVE_LUA
    passdb_register_module(&passdb_lua);
#endif
    passdb_register_module(&passdb_passwd_file);
    passdb_register_module(&passdb_pam);
    passdb_register_module(&passdb_checkpassword);
    passdb_register_module(&passdb_shadow);
    passdb_register_module(&passdb_vpopmail);
    passdb_register_module(&passdb_ldap);
    passdb_register_module(&passdb_sql);
    passdb_register_module(&passdb_sia);
    passdb_register_module(&passdb_static);
    passdb_register_module(&passdb_oauth2);
}

void passdbs_deinit(void)
{
    array_free(&passdb_modules);
    array_free(&passdb_interfaces);
}