src/login-common/client-common-auth.c

	client-common-auth.c revision 53dfcefa9440a49d703e49193819a79be99c9ba6
/* Copyright (c) 2002-2009 Dovecot authors, see the included COPYING file */

#include "common.h"
#include "istream.h"
#include "ostream.h"
#include "str.h"
#include "safe-memset.h"
#include "login-proxy.h"
#include "auth-client.h"
#include "client-common.h"

#include <stdlib.h>

#define PROXY_FAILURE_MSG "Account is temporarily unavailable."

/* If we've been waiting auth server to respond for over this many milliseconds,
   send a "waiting" message. */
#define AUTH_WAITING_TIMEOUT_MSECS (30*1000)
#define AUTH_FAILURE_DELAY_INCREASE_MSECS 5000

#if CLIENT_LOGIN_IDLE_TIMEOUT_MSECS < AUTH_REQUEST_TIMEOUT*1000
#  error client idle timeout must be larger than authentication timeout
#endif

static void client_authfail_delay_timeout(struct client *client)
{
    timeout_remove(&client->to_authfail_delay);

    /* get back to normal client input. */
    i_assert(client->io == NULL);
    client->io = io_add(client->fd, IO_READ, client_input, client);
    client_input(client);
}

void client_auth_failed(struct client *client, bool nodelay)
{
    unsigned int delay_msecs;

    i_free_and_null(client->master_data_prefix);

    if (client->auth_initializing)
        return;

    if (client->io != NULL)
        io_remove(&client->io);
    if (nodelay) {
        client->io = io_add(client->fd, IO_READ, client_input, client);
        client_input(client);
        return;
    }

    /* increase the timeout after each unsuccessful attempt, but don't
       increase it so high that the idle timeout would be triggered */
    delay_msecs = client->auth_attempts * AUTH_FAILURE_DELAY_INCREASE_MSECS;
    if (delay_msecs > CLIENT_LOGIN_IDLE_TIMEOUT_MSECS)
        delay_msecs = CLIENT_LOGIN_IDLE_TIMEOUT_MSECS - 1000;

    i_assert(client->to_authfail_delay == NULL);
    client->to_authfail_delay =
        timeout_add(delay_msecs, client_authfail_delay_timeout, client);
}

static void client_auth_waiting_timeout(struct client *client)
{
    client_send_line(client, CLIENT_CMD_REPLY_STATUS,
             client->master_tag == 0 ?
             AUTH_SERVER_WAITING_MSG : AUTH_MASTER_WAITING_MSG);
    timeout_remove(&client->to_auth_waiting);
}

void client_set_auth_waiting(struct client *client)
{
    i_assert(client->to_auth_waiting == NULL);
    client->to_auth_waiting =
        timeout_add(AUTH_WAITING_TIMEOUT_MSECS,
                client_auth_waiting_timeout, client);
}

static void client_auth_parse_args(struct client *client,
                   const char *const *args,
                   struct client_auth_reply *reply_r)
{
    const char *key, *value, *p;

    memset(reply_r, 0, sizeof(*reply_r));
    reply_r->port = login_default_port;

    for (; *args != NULL; args++) {
        p = strchr(*args, '=');
        if (p == NULL) {
            key = *args;
            value = "";
        } else {
            key = t_strdup_until(*args, p);
            value = p + 1;
        }
        if (strcmp(key, "nologin") == 0)
            reply_r->nologin = TRUE;
        else if (strcmp(key, "nodelay") == 0)
            reply_r->nodelay = TRUE;
        else if (strcmp(key, "proxy") == 0)
            reply_r->proxy = TRUE;
        else if (strcmp(key, "temp") == 0)
            reply_r->temp = TRUE;
        else if (strcmp(key, "authz") == 0)
            reply_r->authz_failure = TRUE;
        else if (strcmp(key, "reason") == 0)
            reply_r->reason = value;
        else if (strcmp(key, "host") == 0)
            reply_r->host = value;
        else if (strcmp(key, "port") == 0)
            reply_r->port = atoi(value);
        else if (strcmp(key, "destuser") == 0)
            reply_r->destuser = value;
        else if (strcmp(key, "pass") == 0)
            reply_r->password = value;
        else if (strcmp(key, "proxy_timeout") == 0)
            reply_r->proxy_timeout_msecs = 1000*atoi(value);
        else if (strcmp(key, "master") == 0)
            reply_r->master_user = value;
        else if (strcmp(key, "ssl") == 0) {
            if (strcmp(value, "yes") == 0)
                reply_r->ssl_flags |= PROXY_SSL_FLAG_YES;
            else if (strcmp(value, "any-cert") == 0) {
                reply_r->ssl_flags |= PROXY_SSL_FLAG_YES |
                    PROXY_SSL_FLAG_ANY_CERT;
            }
        } else if (strcmp(key, "starttls") == 0) {
            reply_r->ssl_flags |= PROXY_SSL_FLAG_STARTTLS;
        } else if (strcmp(key, "user") == 0) {
            /* already handled in login-common */
        } else if (client->set->auth_debug)
            i_info("Ignoring unknown passdb extra field: %s", key);
    }

    if (reply_r->destuser == NULL)
        reply_r->destuser = client->virtual_user;
}

static void proxy_free_password(struct client *client)
{
    if (client->proxy_password == NULL)
        return;

    safe_memset(client->proxy_password, 0, strlen(client->proxy_password));
    i_free_and_null(client->proxy_password);
}

void client_proxy_finish_destroy_client(struct client *client)
{
    string_t *str = t_str_new(128);

    str_printfa(str, "proxy(%s): started proxying to %s:%u",
            client->virtual_user,
            login_proxy_get_host(client->login_proxy),
            login_proxy_get_port(client->login_proxy));
    if (strcmp(client->virtual_user, client->proxy_user) != 0) {
        /* remote username is different, log it */
        str_append_c(str, '/');
        str_append(str, client->proxy_user);
    }
    if (client->proxy_master_user != NULL)
        str_printfa(str, " (master %s)", client->proxy_master_user);

    login_proxy_detach(client->login_proxy, client->input, client->output);

    client->login_proxy = NULL;
    client->input = NULL;
    client->output = NULL;
    client->fd = -1;
    client->proxying = TRUE;
    client_destroy_success(client, str_c(str));
}

void client_proxy_log_failure(struct client *client, const char *line)
{
    string_t *str = t_str_new(128);

    str_printfa(str, "proxy(%s): Login failed to %s:%u",
            client->virtual_user,
            login_proxy_get_host(client->login_proxy),
            login_proxy_get_port(client->login_proxy));
    if (strcmp(client->virtual_user, client->proxy_user) != 0) {
        /* remote username is different, log it */
        str_append_c(str, '/');
        str_append(str, client->proxy_user);
    }
    if (client->proxy_master_user != NULL)
        str_printfa(str, " (master %s)", client->proxy_master_user);
    str_append(str, ": ");
    str_append(str, line);
    i_info("%s", str_c(str));
}

void client_proxy_failed(struct client *client, bool send_line)
{
    if (send_line) {
        client_send_line(client, CLIENT_CMD_REPLY_AUTH_FAIL_TEMP,
                 PROXY_FAILURE_MSG);
    }

    login_proxy_free(&client->login_proxy);
    proxy_free_password(client);
    i_free_and_null(client->proxy_user);
    i_free_and_null(client->proxy_master_user);

    /* call this last - it may destroy the client */
    client_auth_failed(client, TRUE);
}

static void proxy_input(struct client *client)
{
    struct istream *input;
    const char *line;

    if (client->login_proxy == NULL) {
        /* we're just freeing the proxy */
        return;
    }

    input = login_proxy_get_istream(client->login_proxy);
    if (input == NULL) {
        if (client->destroyed) {
            /* we came here from client_destroy() */
            return;
        }

        /* failed for some reason, probably server disconnected */
        client_proxy_failed(client, TRUE);
        return;
    }

    i_assert(!client->destroyed);

    switch (i_stream_read(input)) {
    case -2:
        client_log_err(client, "proxy: Remote input buffer full");
        client_proxy_failed(client, TRUE);
        return;
    case -1:
        client_log_err(client, "proxy: Remote disconnected");
        client_proxy_failed(client, TRUE);
        return;
    }

    while ((line = i_stream_next_line(input)) != NULL) {
        if (client->v.proxy_parse_line(client, line) != 0)
            break;
    }
}

static int proxy_start(struct client *client,
               const struct client_auth_reply *reply)
{
    struct login_proxy_settings proxy_set;

    i_assert(reply->destuser != NULL);
    i_assert(!client->destroyed);

    client->v.proxy_reset(client);

    if (reply->password == NULL) {
        client_log_err(client, "proxy: password not given");
        client_send_line(client, CLIENT_CMD_REPLY_AUTH_FAIL_TEMP,
                 PROXY_FAILURE_MSG);
        return -1;
    }

    i_assert(client->refcount > 1);

    if (client->destroyed) {
        /* connection_queue_add() decided that we were the oldest
           connection and killed us. */
        return -1;
    }
    if (login_proxy_is_ourself(client, reply->host, reply->port,
                   reply->destuser)) {
        client_log_err(client, "Proxying loops to itself");
        client_send_line(client, CLIENT_CMD_REPLY_AUTH_FAIL_TEMP,
                 PROXY_FAILURE_MSG);
        return -1;
    }

    memset(&proxy_set, 0, sizeof(proxy_set));
    proxy_set.host = reply->host;
    proxy_set.port = reply->port;
    proxy_set.connect_timeout_msecs = reply->proxy_timeout_msecs;
    proxy_set.ssl_flags = reply->ssl_flags;

    client->login_proxy =
        login_proxy_new(client, &proxy_set, proxy_input, client);
    if (client->login_proxy == NULL) {
        client_send_line(client, CLIENT_CMD_REPLY_AUTH_FAIL_TEMP,
                 PROXY_FAILURE_MSG);
        return -1;
    }

    client->proxy_user = i_strdup(reply->destuser);
    client->proxy_master_user = i_strdup(reply->master_user);
    client->proxy_password = i_strdup(reply->password);

    /* disable input until authentication is finished */
    if (client->io != NULL)
        io_remove(&client->io);
    return 0;
}

static bool
client_auth_handle_reply(struct client *client,
             const struct client_auth_reply *reply, bool success)
{
    if (reply->proxy) {
        /* we want to proxy the connection to another server.
           don't do this unless authentication succeeded. with
           master user proxying we can get FAIL with proxy still set.

           proxy host=.. [port=..] [destuser=..] pass=.. */
        if (!success)
            return FALSE;
        if (proxy_start(client, reply) < 0)
            client_auth_failed(client, TRUE);
        return TRUE;
    }
    return client->v.auth_handle_reply(client, reply);
}

static void client_auth_input(struct client *client)
{
    char *line;

    if (!client_read(client))
        return;

    /* @UNSAFE */
    line = i_stream_next_line(client->input);
    if (line == NULL)
        return;

    if (strcmp(line, "*") == 0)
        sasl_server_auth_abort(client);
    else {
        client_set_auth_waiting(client);
        auth_client_request_continue(client->auth_request, line);
        io_remove(&client->io);

        /* clear sensitive data */
        safe_memset(line, 0, strlen(line));
    }
}

void client_auth_send_continue(struct client *client, const char *data)
{
    struct const_iovec iov[3];

    iov[0].iov_base = "+ ";
    iov[0].iov_len = 2;
    iov[1].iov_base = data;
    iov[1].iov_len = strlen(data);
    iov[2].iov_base = "\r\n";
    iov[2].iov_len = 2;

    (void)o_stream_sendv(client->output, iov, 3);
}

static void
sasl_callback(struct client *client, enum sasl_server_reply sasl_reply,
          const char *data, const char *const *args)
{
    struct client_auth_reply reply;

    i_assert(!client->destroyed ||
         sasl_reply == SASL_SERVER_REPLY_AUTH_ABORTED ||
         sasl_reply == SASL_SERVER_REPLY_MASTER_FAILED);

    switch (sasl_reply) {
    case SASL_SERVER_REPLY_SUCCESS:
        if (client->to_auth_waiting != NULL)
            timeout_remove(&client->to_auth_waiting);
        if (args != NULL) {
            client_auth_parse_args(client, args, &reply);
            if (client_auth_handle_reply(client, &reply, TRUE))
                break;
        }
        client_destroy_success(client, "Login");
        break;
    case SASL_SERVER_REPLY_AUTH_FAILED:
    case SASL_SERVER_REPLY_AUTH_ABORTED:
        if (client->to_auth_waiting != NULL)
            timeout_remove(&client->to_auth_waiting);
        if (args != NULL) {
            client_auth_parse_args(client, args, &reply);
            reply.nologin = TRUE;
            if (client_auth_handle_reply(client, &reply, FALSE))
                break;
        }

        if (sasl_reply == SASL_SERVER_REPLY_AUTH_ABORTED) {
            client_send_line(client, CLIENT_CMD_REPLY_BAD,
                     "Authentication aborted by client.");
        } else if (data == NULL) {
            client_send_line(client, CLIENT_CMD_REPLY_AUTH_FAILED,
                     AUTH_FAILED_MSG);
        } else {
            client_send_line(client,
                     CLIENT_CMD_REPLY_AUTH_FAIL_REASON,
                     data);
        }

        if (!client->destroyed)
            client_auth_failed(client, reply.nodelay);
        break;
    case SASL_SERVER_REPLY_MASTER_FAILED:
        if (data == NULL)
            client_destroy_internal_failure(client);
        else {
            client_send_line(client,
                     CLIENT_CMD_REPLY_AUTH_FAIL_TEMP, data);
            /* authentication itself succeeded, we just hit some
               internal failure. */
            client_destroy_success(client, data);
        }
        break;
    case SASL_SERVER_REPLY_CONTINUE:
        client->v.auth_send_continue(client, data);

        if (client->to_auth_waiting != NULL)
            timeout_remove(&client->to_auth_waiting);

        i_assert(client->io == NULL);
        client->io = io_add(client->fd, IO_READ,
                    client_auth_input, client);
        client_auth_input(client);
        return;
    }

    client_unref(client);
}

int client_auth_begin(struct client *client, const char *mech_name,
              const char *init_resp)
{
    if (!client->secured && strcmp(client->set->ssl, "required") == 0) {
        if (client->set->verbose_auth) {
            client_log(client, "Login failed: "
                   "SSL required for authentication");
        }
        client->auth_attempts++;
        client_send_line(client, CLIENT_CMD_REPLY_AUTH_FAIL_NOSSL,
            "Authentication not allowed until SSL/TLS is enabled.");
        return 1;
    }


    client_ref(client);
    client->auth_initializing = TRUE;
    sasl_server_auth_begin(client, login_protocol, mech_name,
                   init_resp, sasl_callback);
    client->auth_initializing = FALSE;
    if (!client->authenticating)
        return 1;

    /* don't handle input until we get the initial auth reply */
    if (client->io != NULL)
        io_remove(&client->io);
    client_set_auth_waiting(client);
    return 0;
}

bool client_check_plaintext_auth(struct client *client, bool pass_sent)
{
    if (client->secured || !client->set->disable_plaintext_auth)
        return TRUE;

    if (client->set->verbose_auth) {
        client_log(client, "Login failed: "
               "Plaintext authentication disabled");
    }
    if (pass_sent) {
        client_send_line(client, CLIENT_CMD_REPLY_STATUS_BAD,
             "Plaintext authentication not allowed "
             "without SSL/TLS, but your client did it anyway. "
             "If anyone was listening, the password was exposed.");
    }
    client_send_line(client, CLIENT_CMD_REPLY_AUTH_FAIL_NOSSL,
             AUTH_PLAINTEXT_DISABLED_MSG);
    client->auth_tried_disabled_plaintext = TRUE;
    client->auth_attempts++;
    return FALSE;
}

void clients_notify_auth_connected(void)
{
    struct client *client;

    for (client = clients; client != NULL; client = client->next) {
        if (client->to_auth_waiting != NULL)
            timeout_remove(&client->to_auth_waiting);
        if (!client->greeting_sent)
            client->v.send_greeting(client);
        if (client->input_blocked) {
            client->input_blocked = FALSE;
            client_input(client);
        }
    }
}