src/auth/auth-request-handler.c

	auth-request-handler.c revision 190d84a496d6893ed54fe5bdb9e503285583d13f
/* Copyright (c) 2005-2012 Dovecot authors, see the included COPYING file */

#include "auth-common.h"
#include "ioloop.h"
#include "array.h"
#include "aqueue.h"
#include "base64.h"
#include "hash.h"
#include "str.h"
#include "str-sanitize.h"
#include "master-interface.h"
#include "auth-penalty.h"
#include "auth-request.h"
#include "auth-master-connection.h"
#include "auth-request-handler.h"

#include <stdlib.h>

#define AUTH_FAILURE_DELAY_CHECK_MSECS 500

struct auth_request_handler {
    int refcount;
    pool_t pool;
    struct hash_table *requests;

        unsigned int connect_uid, client_pid;

    auth_request_callback_t *callback;
    void *context;

    auth_request_callback_t *master_callback;

    unsigned int destroyed:1;
};

static ARRAY_DEFINE(auth_failures_arr, struct auth_request *);
static struct aqueue *auth_failures;
static struct timeout *to_auth_failures;

static void auth_failure_timeout(void *context);

#undef auth_request_handler_create
struct auth_request_handler *
auth_request_handler_create(auth_request_callback_t *callback, void *context,
                auth_request_callback_t *master_callback)
{
    struct auth_request_handler *handler;
    pool_t pool;

    pool = pool_alloconly_create("auth request handler", 4096);

    handler = p_new(pool, struct auth_request_handler, 1);
    handler->refcount = 1;
    handler->pool = pool;
    handler->requests = hash_table_create(default_pool, pool, 0, NULL, NULL);
    handler->callback = callback;
    handler->context = context;
    handler->master_callback = master_callback;
    return handler;
}

unsigned int
auth_request_handler_get_request_count(struct auth_request_handler *handler)
{
    return hash_table_count(handler->requests);
}

void auth_request_handler_abort_requests(struct auth_request_handler *handler)
{
    struct hash_iterate_context *iter;
    void *key, *value;

    iter = hash_table_iterate_init(handler->requests);
    while (hash_table_iterate(iter, &key, &value)) {
        struct auth_request *auth_request = value;

        switch (auth_request->state) {
        case AUTH_REQUEST_STATE_NEW:
        case AUTH_REQUEST_STATE_MECH_CONTINUE:
        case AUTH_REQUEST_STATE_FINISHED:
            auth_request_unref(&auth_request);
            hash_table_remove(handler->requests, key);
            break;
        case AUTH_REQUEST_STATE_PASSDB:
        case AUTH_REQUEST_STATE_USERDB:
            /* can't abort a pending passdb/userdb lookup */
            break;
        case AUTH_REQUEST_STATE_MAX:
            i_unreached();
        }
    }
    hash_table_iterate_deinit(&iter);
}

void auth_request_handler_unref(struct auth_request_handler **_handler)
{
        struct auth_request_handler *handler = *_handler;

    *_handler = NULL;

    i_assert(handler->refcount > 0);
    if (--handler->refcount > 0)
        return;

    i_assert(hash_table_count(handler->requests) == 0);

    /* notify parent that we're done with all requests */
    handler->callback(NULL, handler->context);

    hash_table_destroy(&handler->requests);
    pool_unref(&handler->pool);
}

void auth_request_handler_destroy(struct auth_request_handler **_handler)
{
    struct auth_request_handler *handler = *_handler;

    *_handler = NULL;

    i_assert(!handler->destroyed);

    handler->destroyed = TRUE;
    auth_request_handler_unref(&handler);
}

void auth_request_handler_set(struct auth_request_handler *handler,
                  unsigned int connect_uid,
                  unsigned int client_pid)
{
    handler->connect_uid = connect_uid;
    handler->client_pid = client_pid;
}

static void auth_request_handler_remove(struct auth_request_handler *handler,
                    struct auth_request *request)
{
    i_assert(request->handler == handler);

    if (request->removed_from_handler) {
        /* already removed it */
        return;
    }
    request->removed_from_handler = TRUE;

    /* if db lookup is stuck, this call doesn't actually free the auth
       request, so make sure we don't get back here. */
    timeout_remove(&request->to_abort);

    hash_table_remove(handler->requests, POINTER_CAST(request->id));
    auth_request_unref(&request);
}

static void get_client_extra_fields(struct auth_request *request,
                    struct auth_stream_reply *reply)
{
    const char **fields, *extra_fields;
    unsigned int src;
    bool seen_pass = FALSE;

    if (auth_stream_is_empty(request->extra_fields))
        return;

    extra_fields = auth_stream_reply_export(request->extra_fields);

    if (!request->proxy && strstr(extra_fields, "userdb_") == NULL) {
        /* optimization: there are no userdb_* fields, we can just
           import */
        auth_stream_reply_import(reply, extra_fields);
        return;
    }

    fields = t_strsplit_tab(extra_fields);
    for (src = 0; fields[src] != NULL; src++) {
        if (strncmp(fields[src], "userdb_", 7) != 0) {
            if (!seen_pass && strncmp(fields[src], "pass=", 5) == 0)
                seen_pass = TRUE;
            auth_stream_reply_import(reply, fields[src]);
        }
    }

    if (request->proxy) {
        /* we're proxying */
        if (!seen_pass && request->mech_password != NULL) {
            /* send back the password that was sent by user
               (not the password in passdb). */
            auth_stream_reply_add(reply, "pass",
                          request->mech_password);
        }
        if (request->master_user != NULL) {
            /* the master username needs to be forwarded */
            auth_stream_reply_add(reply, "master",
                          request->master_user);
        }
    }
}

static void
auth_request_handle_failure(struct auth_request *request,
                struct auth_stream_reply *reply)
{
        struct auth_request_handler *handler = request->handler;

    if (request->delayed_failure) {
        /* we came here from flush_failures() */
        handler->callback(reply, handler->context);
        return;
    }

    /* remove the request from requests-list */
    auth_request_ref(request);
    auth_request_handler_remove(handler, request);

    if (request->no_failure_delay) {
        /* passdb specifically requested not to delay the reply. */
        handler->callback(reply, handler->context);
        auth_request_unref(&request);
        return;
    }

    /* failure. don't announce it immediately to avoid
       a) timing attacks, b) flooding */
    request->delayed_failure = TRUE;
    handler->refcount++;

    if (auth_penalty != NULL) {
        auth_penalty_update(auth_penalty, request,
                    request->last_penalty + 1);
    }

    auth_request_refresh_last_access(request);
    aqueue_append(auth_failures, &request);
    if (to_auth_failures == NULL) {
        to_auth_failures =
            timeout_add(AUTH_FAILURE_DELAY_CHECK_MSECS,
                    auth_failure_timeout, NULL);
    }
}

static void
auth_request_handler_reply_success_finish(struct auth_request *request)
{
        struct auth_request_handler *handler = request->handler;
    struct auth_stream_reply *reply;

    reply = auth_stream_reply_init(pool_datastack_create());

    if (request->last_penalty != 0 && auth_penalty != NULL) {
        /* reset penalty */
        auth_penalty_update(auth_penalty, request, 0);
    }

    auth_stream_reply_add(reply, "OK", NULL);
    auth_stream_reply_add(reply, NULL, dec2str(request->id));
    auth_stream_reply_add(reply, "user", request->user);
    get_client_extra_fields(request, reply);
    if (request->no_login || handler->master_callback == NULL) {
        /* this request doesn't have to wait for master
           process to pick it up. delete it */
        auth_request_handler_remove(handler, request);
    }
    handler->callback(reply, handler->context);
}

static void
auth_request_handler_reply_failure_finish(struct auth_request *request)
{
    struct auth_stream_reply *reply;

    reply = auth_stream_reply_init(pool_datastack_create());
    auth_stream_reply_add(reply, "FAIL", NULL);
    auth_stream_reply_add(reply, NULL, dec2str(request->id));
    if (request->user != NULL)
        auth_stream_reply_add(reply, "user", request->user);
    else if (request->original_username != NULL) {
        auth_stream_reply_add(reply, "user",
                      request->original_username);
    }

    if (request->internal_failure)
        auth_stream_reply_add(reply, "temp", NULL);
    else if (request->master_user != NULL) {
        /* authentication succeeded, but we can't log in
           as the wanted user */
        auth_stream_reply_add(reply, "authz", NULL);
    }
    if (request->no_failure_delay)
        auth_stream_reply_add(reply, "nodelay", NULL);
    get_client_extra_fields(request, reply);

    switch (request->passdb_result) {
    case PASSDB_RESULT_INTERNAL_FAILURE:
    case PASSDB_RESULT_SCHEME_NOT_AVAILABLE:
    case PASSDB_RESULT_USER_UNKNOWN:
    case PASSDB_RESULT_PASSWORD_MISMATCH:
    case PASSDB_RESULT_OK:
        break;
    case PASSDB_RESULT_USER_DISABLED:
        auth_stream_reply_add(reply, "user_disabled", NULL);
        break;
    case PASSDB_RESULT_PASS_EXPIRED:
        auth_stream_reply_add(reply, "pass_expired", NULL);
        break;
    }

    auth_request_handle_failure(request, reply);
}

static void
auth_request_handler_proxy_callback(bool success, struct auth_request *request)
{
        struct auth_request_handler *handler = request->handler;

    if (success)
        auth_request_handler_reply_success_finish(request);
    else
        auth_request_handler_reply_failure_finish(request);
        auth_request_handler_unref(&handler);
}

void auth_request_handler_reply(struct auth_request *request,
                enum auth_client_result result,
                const void *auth_reply, size_t reply_size)
{
        struct auth_request_handler *handler = request->handler;
    struct auth_stream_reply *reply;
    string_t *str;
    int ret;

    if (handler->destroyed) {
        /* the client connection was already closed. we can't do
           anything but abort this request */
        request->internal_failure = TRUE;
        result = AUTH_CLIENT_RESULT_FAILURE;
        /* make sure this request is set to finished state
           (it's not with result=continue) */
        auth_request_set_state(request, AUTH_REQUEST_STATE_FINISHED);
    }

    switch (result) {
    case AUTH_CLIENT_RESULT_CONTINUE:
        reply = auth_stream_reply_init(pool_datastack_create());
        auth_stream_reply_add(reply, "CONT", NULL);
        auth_stream_reply_add(reply, NULL, dec2str(request->id));

        str = t_str_new(MAX_BASE64_ENCODED_SIZE(reply_size));
        base64_encode(auth_reply, reply_size, str);
        auth_stream_reply_add(reply, NULL, str_c(str));

        request->accept_input = TRUE;
        handler->callback(reply, handler->context);
        break;
    case AUTH_CLIENT_RESULT_SUCCESS:
        if (reply_size > 0) {
            str = t_str_new(MAX_BASE64_ENCODED_SIZE(reply_size));
            base64_encode(auth_reply, reply_size, str);
            auth_stream_reply_add(request->extra_fields, "resp", str_c(str));
        }
        ret = auth_request_proxy_finish(request,
                auth_request_handler_proxy_callback);
        if (ret < 0)
            auth_request_handler_reply_failure_finish(request);
        else if (ret > 0)
            auth_request_handler_reply_success_finish(request);
        else
            return;
        break;
    case AUTH_CLIENT_RESULT_FAILURE:
        auth_request_proxy_finish_failure(request);
        auth_request_handler_reply_failure_finish(request);
        break;
    }
    /* NOTE: request may be destroyed now */

        auth_request_handler_unref(&handler);
}

void auth_request_handler_reply_continue(struct auth_request *request,
                     const void *reply, size_t reply_size)
{
    auth_request_handler_reply(request, AUTH_CLIENT_RESULT_CONTINUE,
                   reply, reply_size);
}

static void auth_request_handler_auth_fail(struct auth_request_handler *handler,
                       struct auth_request *request,
                       const char *reason)
{
    struct auth_stream_reply *reply;

    auth_request_log_info(request, request->mech->mech_name, "%s", reason);

    reply = auth_stream_reply_init(pool_datastack_create());
    auth_stream_reply_add(reply, "FAIL", NULL);
    auth_stream_reply_add(reply, NULL, dec2str(request->id));
    auth_stream_reply_add(reply, "reason", reason);

    handler->callback(reply, handler->context);
    auth_request_handler_remove(handler, request);
}

static void auth_request_timeout(struct auth_request *request)
{
    const char *str;

    str = t_strdup_printf("Request %u.%u timeouted after %u secs, state=%d",
                  request->handler->client_pid, request->id,
                  (unsigned int)(time(NULL) - request->last_access),
                  request->state);
    if (request->state != AUTH_REQUEST_STATE_MECH_CONTINUE) {
        /* client's fault */
        auth_request_log_error(request, request->mech->mech_name,
                       "%s", str);
    } else if (request->set->verbose) {
        auth_request_log_info(request, request->mech->mech_name,
                      "%s", str);
    }
    auth_request_handler_remove(request->handler, request);
}

static void auth_request_penalty_finish(struct auth_request *request)
{
    timeout_remove(&request->to_penalty);
    auth_request_initial(request);
}

static void
auth_penalty_callback(unsigned int penalty, struct auth_request *request)
{
    unsigned int secs;

    request->last_penalty = penalty;

    if (penalty == 0)
        auth_request_initial(request);
    else {
        secs = auth_penalty_to_secs(penalty);
        request->to_penalty = timeout_add(secs * 1000,
                          auth_request_penalty_finish,
                          request);
    }
}

bool auth_request_handler_auth_begin(struct auth_request_handler *handler,
                     const char *args)
{
    const struct mech_module *mech;
    struct auth_request *request;
    const char *const *list, *name, *arg, *initial_resp;
    void *initial_resp_data;
    unsigned int id;
    buffer_t *buf;

    i_assert(!handler->destroyed);

    /* <id> <mechanism> [...] */
    list = t_strsplit_tab(args);
    if (list[0] == NULL || list[1] == NULL ||
        str_to_uint(list[0], &id) < 0) {
        i_error("BUG: Authentication client %u "
            "sent broken AUTH request", handler->client_pid);
        return FALSE;
    }

    mech = mech_module_find(list[1]);
    if (mech == NULL) {
        /* unsupported mechanism */
        i_error("BUG: Authentication client %u requested unsupported "
            "authentication mechanism %s", handler->client_pid,
            str_sanitize(list[1], MAX_MECH_NAME_LEN));
        return FALSE;
    }

    request = auth_request_new(mech);
    request->handler = handler;
    request->connect_uid = handler->connect_uid;
    request->client_pid = handler->client_pid;
    request->id = id;

    /* parse optional parameters */
    initial_resp = NULL;
    for (list += 2; *list != NULL; list++) {
        arg = strchr(*list, '=');
        if (arg == NULL) {
            name = *list;
            arg = "";
        } else {
            name = t_strdup_until(*list, arg);
            arg++;
        }

        if (auth_request_import_auth(request, name, arg))
            ;
        else if (strcmp(name, "resp") == 0) {
            initial_resp = arg;
            /* this must be the last parameter */
            list++;
            break;
        }
    }

    if (*list != NULL) {
        i_error("BUG: Authentication client %u "
            "sent AUTH parameters after 'resp'",
            handler->client_pid);
        auth_request_unref(&request);
        return FALSE;
    }

    if (request->service == NULL) {
        i_error("BUG: Authentication client %u "
            "didn't specify service in request",
            handler->client_pid);
        auth_request_unref(&request);
        return FALSE;
    }
    if (hash_table_lookup(handler->requests, POINTER_CAST(id)) != NULL) {
        i_error("BUG: Authentication client %u "
            "sent a duplicate ID %u", handler->client_pid, id);
        auth_request_unref(&request);
        return FALSE;
    }
    auth_request_init(request);

    request->to_abort = timeout_add(MASTER_AUTH_SERVER_TIMEOUT_SECS * 1000,
                    auth_request_timeout, request);
    hash_table_insert(handler->requests, POINTER_CAST(id), request);

    if (request->set->ssl_require_client_cert &&
        !request->valid_client_cert) {
        /* we fail without valid certificate */
                auth_request_handler_auth_fail(handler, request,
            "Client didn't present valid SSL certificate");
        return TRUE;
    }

    /* Empty initial response is a "=" base64 string. Completely empty
       string shouldn't really be sent, but at least Exim does it,
       so just allow it for backwards compatibility.. */
    if (initial_resp != NULL && *initial_resp != '\0') {
        size_t len = strlen(initial_resp);

        buf = buffer_create_dynamic(pool_datastack_create(),
                        MAX_BASE64_DECODED_SIZE(len));
        if (base64_decode(initial_resp, len, NULL, buf) < 0) {
                        auth_request_handler_auth_fail(handler, request,
                "Invalid base64 data in initial response");
            return TRUE;
        }
        initial_resp_data =
            p_malloc(request->pool, I_MAX(buf->used, 1));
        memcpy(initial_resp_data, buf->data, buf->used);
        request->initial_response = initial_resp_data;
        request->initial_response_len = buf->used;
    }

    /* handler is referenced until auth_request_handler_reply()
       is called. */
    handler->refcount++;

    /* before we start authenticating, see if we need to wait first */
    auth_penalty_lookup(auth_penalty, request, auth_penalty_callback);
    return TRUE;
}

bool auth_request_handler_auth_continue(struct auth_request_handler *handler,
                    const char *args)
{
    struct auth_request *request;
    const char *data;
    size_t data_len;
    buffer_t *buf;
    unsigned int id;

    data = strchr(args, '\t');
    if (data == NULL || str_to_uint(t_strdup_until(args, data), &id) < 0) {
        i_error("BUG: Authentication client sent broken CONT request");
        return FALSE;
    }
    data++;

    request = hash_table_lookup(handler->requests, POINTER_CAST(id));
    if (request == NULL) {
        struct auth_stream_reply *reply;

        reply = auth_stream_reply_init(pool_datastack_create());
        auth_stream_reply_add(reply, "FAIL", NULL);
        auth_stream_reply_add(reply, NULL, dec2str(id));
        auth_stream_reply_add(reply, "reason",
                      "Authentication request timed out");
        handler->callback(reply, handler->context);
        return TRUE;
    }

    /* accept input only once after mechanism has sent a CONT reply */
    if (!request->accept_input) {
        auth_request_handler_auth_fail(handler, request,
                           "Unexpected continuation");
        return TRUE;
    }
    request->accept_input = FALSE;

    data_len = strlen(data);
    buf = buffer_create_dynamic(pool_datastack_create(),
                    MAX_BASE64_DECODED_SIZE(data_len));
    if (base64_decode(data, data_len, NULL, buf) < 0) {
        auth_request_handler_auth_fail(handler, request,
            "Invalid base64 data in continued response");
        return TRUE;
    }

    /* handler is referenced until auth_request_handler_reply()
       is called. */
    handler->refcount++;
    auth_request_continue(request, buf->data, buf->used);
    return TRUE;
}

static void userdb_callback(enum userdb_result result,
                struct auth_request *request)
{
        struct auth_request_handler *handler = request->handler;
    struct auth_stream_reply *reply;
    const char *value;

    i_assert(request->state == AUTH_REQUEST_STATE_USERDB);

    auth_request_set_state(request, AUTH_REQUEST_STATE_FINISHED);

    if (request->userdb_lookup_failed)
        result = USERDB_RESULT_INTERNAL_FAILURE;

    reply = auth_stream_reply_init(pool_datastack_create());
    switch (result) {
    case USERDB_RESULT_INTERNAL_FAILURE:
        auth_stream_reply_add(reply, "FAIL", NULL);
        auth_stream_reply_add(reply, NULL, dec2str(request->id));
        if (request->userdb_lookup_failed) {
            value = auth_stream_reply_find(request->userdb_reply,
                               "reason");
            if (value != NULL)
                auth_stream_reply_add(reply, "reason", value);
        }
        break;
    case USERDB_RESULT_USER_UNKNOWN:
        auth_stream_reply_add(reply, "NOTFOUND", NULL);
        auth_stream_reply_add(reply, NULL, dec2str(request->id));
        break;
    case USERDB_RESULT_OK:
        auth_stream_reply_add(reply, "USER", NULL);
        auth_stream_reply_add(reply, NULL, dec2str(request->id));
        if (request->master_user != NULL &&
            auth_stream_reply_find(request->userdb_reply,
                       "master_user") == NULL) {
            auth_stream_reply_add(request->userdb_reply,
                          "master_user",
                          request->master_user);
        }
        if (*request->set->anonymous_username != '\0' &&
            strcmp(request->user,
               request->set->anonymous_username) == 0) {
            /* this is an anonymous login, either via ANONYMOUS
               SASL mechanism or simply logging in as the anonymous
               user via another mechanism */
            auth_stream_reply_add(request->userdb_reply,
                          "anonymous", NULL);
        }
        auth_stream_reply_import(reply,
            auth_stream_reply_export(request->userdb_reply));
        break;
    }
    handler->master_callback(reply, request->master);

    auth_master_connection_unref(&request->master);
    auth_request_unref(&request);
        auth_request_handler_unref(&handler);
}

bool auth_request_handler_master_request(struct auth_request_handler *handler,
                     struct auth_master_connection *master,
                     unsigned int id,
                     unsigned int client_id)
{
    struct auth_request *request;
    struct auth_stream_reply *reply;

    reply = auth_stream_reply_init(pool_datastack_create());

    request = hash_table_lookup(handler->requests, POINTER_CAST(client_id));
    if (request == NULL) {
        i_error("Master request %u.%u not found",
            handler->client_pid, client_id);
        auth_stream_reply_add(reply, "FAIL", NULL);
        auth_stream_reply_add(reply, NULL, dec2str(id));
        if (handler->master_callback == NULL)
            return FALSE;
        handler->master_callback(reply, master);
        return TRUE;
    }

    auth_request_ref(request);
    auth_request_handler_remove(handler, request);

    if (request->state != AUTH_REQUEST_STATE_FINISHED ||
        !request->successful) {
        i_error("Master requested unfinished authentication request "
            "%u.%u", handler->client_pid, client_id);
        auth_stream_reply_add(reply, "FAIL", NULL);
        auth_stream_reply_add(reply, NULL, dec2str(id));
        handler->master_callback(reply, master);
        auth_request_unref(&request);
    } else {
        /* the request isn't being referenced anywhere anymore,
           so we can do a bit of kludging.. replace the request's
           old client_id with master's id. */
        auth_request_set_state(request, AUTH_REQUEST_STATE_USERDB);
        request->id = id;
        request->master = master;

        /* master and handler are referenced until userdb_callback i
           s called. */
        auth_master_connection_ref(master);
        handler->refcount++;
        auth_request_lookup_user(request, userdb_callback);
    }
    return TRUE;
}

void auth_request_handler_cancel_request(struct auth_request_handler *handler,
                     unsigned int client_id)
{
    struct auth_request *request;

    request = hash_table_lookup(handler->requests, POINTER_CAST(client_id));
    if (request != NULL)
        auth_request_handler_remove(handler, request);
}

void auth_request_handler_flush_failures(bool flush_all)
{
    struct auth_request **auth_requests, *auth_request;
    unsigned int i, count;
    time_t diff;

    count = aqueue_count(auth_failures);
    if (count == 0) {
        if (to_auth_failures != NULL)
            timeout_remove(&to_auth_failures);
        return;
    }

    auth_requests = array_idx_modifiable(&auth_failures_arr, 0);
    for (i = 0; i < count; i++) {
        auth_request = auth_requests[aqueue_idx(auth_failures, 0)];

        /* FIXME: assumess that failure_delay is always the same. */
        diff = ioloop_time - auth_request->last_access;
        if (diff < (time_t)auth_request->set->failure_delay &&
            !flush_all)
            break;

        aqueue_delete_tail(auth_failures);

        i_assert(auth_request->state == AUTH_REQUEST_STATE_FINISHED);
        auth_request_handler_reply(auth_request,
                       AUTH_CLIENT_RESULT_FAILURE, NULL, 0);
        auth_request_unref(&auth_request);
    }
}

static void auth_failure_timeout(void *context ATTR_UNUSED)
{
    auth_request_handler_flush_failures(FALSE);
}

void auth_request_handler_init(void)
{
    i_array_init(&auth_failures_arr, 128);
    auth_failures = aqueue_init(&auth_failures_arr.arr);
}

void auth_request_handler_deinit(void)
{
    auth_request_handler_flush_failures(TRUE);
    array_free(&auth_failures_arr);
    aqueue_deinit(&auth_failures);

    if (to_auth_failures != NULL)
        timeout_remove(&to_auth_failures);
}