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

	client-common-auth.c revision f0339f522dc9c8e2e8a29ef9a3f937c431c6bd1b
/* Copyright (c) 2002-2016 Dovecot authors, see the included COPYING file */

#include "hostpid.h"
#include "login-common.h"
#include "iostream.h"
#include "istream.h"
#include "ostream.h"
#include "str.h"
#include "safe-memset.h"
#include "time-util.h"
#include "login-proxy.h"
#include "auth-client.h"
#include "dsasl-client.h"
#include "master-service-ssl-settings.h"
#include "client-common.h"

#define PROXY_FAILURE_MSG "Account is temporarily unavailable."
#define PROXY_DEFAULT_TIMEOUT_MSECS (1000*30)

/* 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_WAITING_WARNING_TIMEOUT_MSECS (10*1000)

static void client_auth_failed(struct client *client)
{
    i_free_and_null(client->master_data_prefix);
    if (client->auth_response != NULL)
        str_truncate(client->auth_response, 0);

    if (client->auth_initializing || client->destroyed)
        return;

    if (client->io != NULL)
        io_remove(&client->io);

    client->io = io_add(client->fd, IO_READ, client_input, client);
    client_input(client);
}

static void client_auth_waiting_timeout(struct client *client)
{
    if (!client->notified_auth_ready) {
        client_log_warn(client, "Auth process not responding, "
                "delayed sending initial response (greeting)");
    }
    client_notify_status(client, FALSE, 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(!client->notified_auth_ready ?
                AUTH_WAITING_WARNING_TIMEOUT_MSECS :
                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));

    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, "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, "user_disabled") == 0)
            client->auth_user_disabled = TRUE;
        else if (strcmp(key, "pass_expired") == 0)
            client->auth_pass_expired = 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, "hostip") == 0)
            reply_r->hostip = value;
        else if (strcmp(key, "source_ip") == 0)
            reply_r->source_ip = value;
        else if (strcmp(key, "port") == 0) {
            if (net_str2port(value, &reply_r->port) < 0) {
                i_error("Auth service returned invalid "
                    "port number: %s", 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) {
            if (str_to_uint(value, &reply_r->proxy_timeout_msecs) < 0) {
                i_error("BUG: Auth service returned invalid "
                    "proxy_timeout value: %s", value);
            }
            reply_r->proxy_timeout_msecs *= 1000;
        } else if (strcmp(key, "proxy_refresh") == 0) {
            if (str_to_uint(value, &reply_r->proxy_refresh_secs) < 0) {
                i_error("BUG: Auth service returned invalid "
                    "proxy_refresh value: %s", value);
            }
        } else if (strcmp(key, "proxy_mech") == 0)
            reply_r->proxy_mech = value;
        else if (strcmp(key, "proxy_nopipelining") == 0)
            reply_r->proxy_nopipelining = TRUE;
        else if (strcmp(key, "master") == 0)
            reply_r->master_user = value;
        else if (strcmp(key, "ssl") == 0) {
            reply_r->ssl_flags |= PROXY_SSL_FLAG_YES;
            if (strcmp(value, "any-cert") == 0)
                reply_r->ssl_flags |= PROXY_SSL_FLAG_ANY_CERT;
            if (reply_r->port == 0)
                reply_r->port = login_binary->default_ssl_port;
        } else if (strcmp(key, "starttls") == 0) {
            reply_r->ssl_flags |= PROXY_SSL_FLAG_YES |
                PROXY_SSL_FLAG_STARTTLS;
            if (strcmp(value, "any-cert") == 0)
                reply_r->ssl_flags |= PROXY_SSL_FLAG_ANY_CERT;
        } else if (strcmp(key, "user") == 0 ||
               strcmp(key, "postlogin_socket") == 0) {
            /* already handled in sasl-server.c */
        } else if (client->set->auth_debug)
            i_debug("Ignoring unknown passdb extra field: %s", key);
    }
    if (reply_r->port == 0)
        reply_r->port = login_binary->default_port;

    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);

    if (client->input->closed) {
        /* input stream got closed in client_send_raw_data().
           In most places we don't have to check for this explicitly,
           but login_proxy_detach() attempts to get and use the
           istream's fd, which is now -1. */
        client_destroy(client, "Disconnected");
        return;
    }

    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_destroy_success(client, str_c(str));
}

static void client_proxy_error(struct client *client, const char *text)
{
    client->v.proxy_error(client, text);
}

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);
    client_log(client, str_c(str));
}

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

    if (client->proxy_sasl_client != NULL)
        dsasl_client_free(&client->proxy_sasl_client);
    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);
}

static void proxy_input(struct client *client)
{
    struct istream *input;
    struct ostream *output;
    const char *line;
    unsigned int duration;

    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:
        line = i_stream_next_line(input);
        duration = ioloop_time - client->created;
        client_log_err(client, t_strdup_printf(
            "proxy: Remote %s:%u disconnected: %s "
            "(state=%u, duration=%us)%s",
            login_proxy_get_host(client->login_proxy),
            login_proxy_get_port(client->login_proxy),
            io_stream_get_disconnect_reason(input, NULL),
            client->proxy_state, duration,
            line == NULL ? "" : t_strdup_printf(
                " - BUG: line not read: %s", line)));
        client_proxy_failed(client, TRUE);
        return;
    }

    output = client->output;
    o_stream_ref(output);
    o_stream_cork(output);
    while ((line = i_stream_next_line(input)) != NULL) {
        if (client->v.proxy_parse_line(client, line) != 0)
            break;
    }
    o_stream_uncork(output);
    o_stream_unref(&output);
}

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

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

    client->proxy_mech = NULL;
    client->v.proxy_reset(client);

    if (reply->password == NULL) {
        client_log_err(client, "proxy: password not given");
        client_proxy_error(client, PROXY_FAILURE_MSG);
        return -1;
    }
    if (reply->host == NULL || *reply->host == '\0') {
        client_log_err(client, "proxy: host not given");
        client_proxy_error(client, PROXY_FAILURE_MSG);
        return -1;
    }

    if (reply->proxy_mech != NULL) {
        sasl_mech = dsasl_client_mech_find(reply->proxy_mech);
        if (sasl_mech == NULL) {
            client_log_err(client, t_strdup_printf(
                "proxy: Unsupported SASL mechanism %s",
                reply->proxy_mech));
            client_proxy_error(client, PROXY_FAILURE_MSG);
            return -1;
        }
    } else if (reply->master_user != NULL) {
        /* have to use PLAIN authentication with master user logins */
        sasl_mech = &dsasl_client_mech_plain;
    }

    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_proxy_error(client, PROXY_FAILURE_MSG);
        return -1;
    }

    memset(&proxy_set, 0, sizeof(proxy_set));
    proxy_set.host = reply->host;
    if (reply->hostip != NULL &&
        net_addr2ip(reply->hostip, &proxy_set.ip) < 0)
        proxy_set.ip.family = 0;
    if (reply->source_ip != NULL) {
        if (net_addr2ip(reply->source_ip, &proxy_set.source_ip) < 0)
            proxy_set.source_ip.family = 0;
    } else if (login_source_ips_count > 0) {
        /* select the next source IP with round robin. */
        proxy_set.source_ip = login_source_ips[login_source_ips_idx];
        login_source_ips_idx =
            (login_source_ips_idx + 1) % login_source_ips_count;
    }
    proxy_set.port = reply->port;
    proxy_set.connect_timeout_msecs = reply->proxy_timeout_msecs;
    if (proxy_set.connect_timeout_msecs == 0)
        proxy_set.connect_timeout_msecs = PROXY_DEFAULT_TIMEOUT_MSECS;
    proxy_set.notify_refresh_secs = reply->proxy_refresh_secs;
    proxy_set.ssl_flags = reply->ssl_flags;

    if (login_proxy_new(client, &proxy_set, proxy_input) < 0) {
        client_proxy_error(client, PROXY_FAILURE_MSG);
        return -1;
    }

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

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

static void ATTR_NULL(3, 4)
client_auth_result(struct client *client, enum client_auth_result result,
           const struct client_auth_reply *reply, const char *text)
{
    o_stream_cork(client->output);
    client->v.auth_result(client, result, reply, text);
    o_stream_uncork(client->output);
}

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);
        else {
            /* this for plugins being able th hook into auth reply
               when proxying is used */
            client_auth_result(client, CLIENT_AUTH_RESULT_SUCCESS,
                       reply, NULL);
        }
        return TRUE;
    }

    if (reply->host != NULL) {
        const char *reason;

        if (reply->reason != NULL)
            reason = reply->reason;
        else if (reply->nologin)
            reason = "Try this server instead.";
        else
            reason = "Logged in, but you should use this server instead.";

        if (reply->nologin) {
            client_auth_result(client,
                CLIENT_AUTH_RESULT_REFERRAL_NOLOGIN,
                reply, reason);
        } else {
            client_auth_result(client,
                CLIENT_AUTH_RESULT_REFERRAL_SUCCESS,
                reply, reason);
            return TRUE;
        }
    } else if (reply->nologin) {
        /* Authentication went ok, but for some reason user isn't
           allowed to log in. Shouldn't probably happen. */
        if (reply->reason != NULL) {
            client_auth_result(client,
                CLIENT_AUTH_RESULT_AUTHFAILED_REASON,
                reply, reply->reason);
        } else if (reply->temp) {
            const char *timestamp, *msg;

            timestamp = t_strflocaltime("%Y-%m-%d %H:%M:%S", ioloop_time);
            msg = t_strdup_printf(AUTH_TEMP_FAILED_MSG" [%s:%s]",
                      my_hostname, timestamp);
            client_auth_result(client, CLIENT_AUTH_RESULT_TEMPFAIL,
                       reply, msg);
        } else if (reply->authz_failure) {
            client_auth_result(client,
                CLIENT_AUTH_RESULT_AUTHZFAILED, reply,
                "Authorization failed");
        } else {
            client_auth_result(client,
                CLIENT_AUTH_RESULT_AUTHFAILED, reply,
                AUTH_FAILED_MSG);
        }
    } else {
        /* normal login/failure */
        return FALSE;
    }

    i_assert(reply->nologin);

    if (!client->destroyed)
        client_auth_failed(client);
    return TRUE;
}

void client_auth_respond(struct client *client, const char *response)
{
    client->auth_waiting = FALSE;
    client_set_auth_waiting(client);
    auth_client_request_continue(client->auth_request, response);
    io_remove(&client->io);
}

void client_auth_abort(struct client *client)
{
    sasl_server_auth_abort(client);
}

void client_auth_fail(struct client *client, const char *text)
{
    sasl_server_auth_failed(client, text);
}

int client_auth_read_line(struct client *client)
{
    const unsigned char *data;
    size_t i, size;
    unsigned int len;

    if (i_stream_read_more(client->input, &data, &size) == -1) {
        client_destroy(client, "Disconnected");
        return -1;
    }

    /* see if we have a full line */
    for (i = 0; i < size; i++) {
        if (data[i] == '\n')
            break;
    }
    if (client->auth_response == NULL)
        client->auth_response = str_new(default_pool, I_MAX(i+1, 256));
    if (str_len(client->auth_response) + i > LOGIN_MAX_AUTH_BUF_SIZE) {
        client_destroy(client, "Authentication response too large");
        return -1;
    }
    str_append_n(client->auth_response, data, i);
    i_stream_skip(client->input, i == size ? size : i+1);

    /* drop trailing \r */
    len = str_len(client->auth_response);
    if (len > 0 && str_c(client->auth_response)[len-1] == '\r')
        str_truncate(client->auth_response, len-1);

    return i < size ? 1 : 0;
}

void client_auth_parse_response(struct client *client)
{
    if (client_auth_read_line(client) <= 0)
        return;

    if (strcmp(str_c(client->auth_response), "*") == 0) {
        sasl_server_auth_abort(client);
        return;
    }

    client_auth_respond(client, str_c(client->auth_response));
    memset(str_c_modifiable(client->auth_response), 0,
           str_len(client->auth_response));
}

static void client_auth_input(struct client *client)
{
    i_assert(client->v.auth_parse_response != NULL);
    client->v.auth_parse_response(client);
}

void client_auth_send_challenge(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;

    o_stream_nsendv(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);

    memset(&reply, 0, sizeof(reply));
    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);
            reply.all_fields = args;
            if (client_auth_handle_reply(client, &reply, TRUE))
                break;
        }
        client_auth_result(client, CLIENT_AUTH_RESULT_SUCCESS,
                   &reply, NULL);
        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;
            reply.all_fields = args;
            if (client_auth_handle_reply(client, &reply, FALSE))
                break;
        }

        if (sasl_reply == SASL_SERVER_REPLY_AUTH_ABORTED) {
            client_auth_result(client, CLIENT_AUTH_RESULT_ABORTED,
                &reply, "Authentication aborted by client.");
        } else if (data == NULL) {
            client_auth_result(client,
                CLIENT_AUTH_RESULT_AUTHFAILED, &reply,
                AUTH_FAILED_MSG);
        } else {
            client_auth_result(client,
                CLIENT_AUTH_RESULT_AUTHFAILED_REASON, &reply,
                data);
        }

        if (!client->destroyed)
            client_auth_failed(client);
        break;
    case SASL_SERVER_REPLY_MASTER_FAILED:
        if (data != NULL) {
            /* authentication itself succeeded, we just hit some
               internal failure. */
            client_auth_result(client, CLIENT_AUTH_RESULT_TEMPFAIL,
                       &reply, data);
        }

        /* the fd may still be hanging somewhere in kernel or another
           process. make sure the client gets disconnected. */
        if (shutdown(client->fd, SHUT_RDWR) < 0 && errno != ENOTCONN)
            i_error("shutdown() failed: %m");

        if (data == NULL)
            client_destroy_internal_failure(client);
        else
            client_destroy_success(client, data);
        break;
    case SASL_SERVER_REPLY_CONTINUE:
        i_assert(client->v.auth_send_challenge != NULL);
        client->v.auth_send_challenge(client, data);

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

        if (client->auth_response != NULL)
            str_truncate(client->auth_response, 0);

        i_assert(client->io == NULL);
        client->auth_waiting = TRUE;
        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->ssl_set->ssl, "required") == 0) {
        if (client->set->auth_verbose) {
            client_log(client, "Login failed: "
                   "SSL required for authentication");
        }
        client->auth_attempts++;
        client_auth_result(client, CLIENT_AUTH_RESULT_SSL_REQUIRED, NULL,
            "Authentication not allowed until SSL/TLS is enabled.");
        return 1;
    }


    client_ref(client);
    client->auth_initializing = TRUE;
    sasl_server_auth_begin(client, login_binary->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 &&
                strcmp(client->ssl_set->ssl, "required") != 0))
        return TRUE;

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

void clients_notify_auth_connected(void)
{
    struct client *client, *next;

    for (client = clients; client != NULL; client = next) {
        next = client->next;

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

        client_notify_auth_ready(client);

        if (client->input_blocked) {
            client->input_blocked = FALSE;
            client_input(client);
        }
    }
}