src/login-common/sasl-server.c

	sasl-server.c revision 3609e0b9b8fcd1a183a785af690cdcad33c345aa
/* Copyright (c) 2002-2017 Dovecot authors, see the included COPYING file */

#include "login-common.h"
#include "str.h"
#include "base64.h"
#include "buffer.h"
#include "hex-binary.h"
#include "ioloop.h"
#include "istream.h"
#include "write-full.h"
#include "strescape.h"
#include "str-sanitize.h"
#include "anvil-client.h"
#include "auth-client.h"
#include "iostream-ssl.h"
#include "master-service.h"
#include "master-service-ssl-settings.h"
#include "master-interface.h"
#include "master-auth.h"
#include "client-common.h"

#include <unistd.h>

#define ERR_TOO_MANY_USERIP_CONNECTIONS \
    "Maximum number of connections from user+IP exceeded " \
    "(mail_max_userip_connections=%u)"

struct anvil_request {
    struct client *client;
    unsigned int auth_pid, auth_id;
    unsigned char cookie[MASTER_AUTH_COOKIE_SIZE];
};

const struct auth_mech_desc *
sasl_server_get_advertised_mechs(struct client *client, unsigned int *count_r)
{
    const struct auth_mech_desc *mech;
    struct auth_mech_desc *ret_mech;
    unsigned int i, j, count;

    mech = auth_client_get_available_mechs(auth_client, &count);
    if (count == 0 || (!client->secured &&
               strcmp(client->ssl_set->ssl, "required") == 0)) {
        *count_r = 0;
        return NULL;
    }

    ret_mech = t_new(struct auth_mech_desc, count);
    for (i = j = 0; i < count; i++) {
        /* a) transport is secured
           b) auth mechanism isn't plaintext
           c) we allow insecure authentication
        */
        if ((mech[i].flags & MECH_SEC_PRIVATE) == 0 &&
            (client->secured || !client->set->disable_plaintext_auth ||
             (mech[i].flags & MECH_SEC_PLAINTEXT) == 0))
            ret_mech[j++] = mech[i];
    }
    *count_r = j;
    return ret_mech;
}

static enum auth_request_flags
client_get_auth_flags(struct client *client)
{
        enum auth_request_flags auth_flags = 0;

    if (client->ssl_iostream != NULL &&
        ssl_iostream_has_valid_client_cert(client->ssl_iostream))
        auth_flags |= AUTH_REQUEST_FLAG_VALID_CLIENT_CERT;
    if (client->tls)
        auth_flags |= AUTH_REQUEST_FLAG_TRANSPORT_SECURITY_TLS;
    if (client->secured)
        auth_flags |= AUTH_REQUEST_FLAG_SECURED;
    if (login_binary->sasl_support_final_reply)
        auth_flags |= AUTH_REQUEST_FLAG_SUPPORT_FINAL_RESP;
    return auth_flags;
}

static void ATTR_NULL(3, 4)
call_client_callback(struct client *client, enum sasl_server_reply reply,
             const char *data, const char *const *args)
{
    sasl_server_callback_t *sasl_callback;

    i_assert(reply != SASL_SERVER_REPLY_CONTINUE);

    sasl_callback = client->sasl_callback;
    client->sasl_callback = NULL;

    sasl_callback(client, reply, data, args);
    /* NOTE: client may be destroyed now */
}

static void
master_auth_callback(const struct master_auth_reply *reply, void *context)
{
    struct client *client = context;
    enum sasl_server_reply sasl_reply = SASL_SERVER_REPLY_MASTER_FAILED;
    const char *data = NULL;

    client->master_tag = 0;
    client->authenticating = FALSE;
    if (reply != NULL) {
        switch (reply->status) {
        case MASTER_AUTH_STATUS_OK:
            sasl_reply = SASL_SERVER_REPLY_SUCCESS;
            break;
        case MASTER_AUTH_STATUS_INTERNAL_ERROR:
            sasl_reply = SASL_SERVER_REPLY_MASTER_FAILED;
            break;
        }
        client->mail_pid = reply->mail_pid;
    } else {
        auth_client_send_cancel(auth_client, client->master_auth_id);
    }
    call_client_callback(client, sasl_reply, data, NULL);
}

static int master_send_request(struct anvil_request *anvil_request)
{
    struct client *client = anvil_request->client;
    struct master_auth_request_params params;
    struct master_auth_request req;
    const unsigned char *data;
    size_t size;
    buffer_t *buf;
    const char *session_id = client_get_session_id(client);
    int fd;
    bool close_fd;

    if (client_get_plaintext_fd(client, &fd, &close_fd) < 0)
        return -1;

    i_zero(&req);
    req.auth_pid = anvil_request->auth_pid;
    req.auth_id = anvil_request->auth_id;
    req.local_ip = client->local_ip;
    req.remote_ip = client->ip;
    req.local_port = client->local_port;
    req.remote_port = client->remote_port;
    req.client_pid = getpid();
    if (client->ssl_iostream != NULL &&
        ssl_iostream_get_compression(client->ssl_iostream) != NULL)
        req.flags |= MAIL_AUTH_REQUEST_FLAG_TLS_COMPRESSION;
    if (client->secured)
        req.flags |= MAIL_AUTH_REQUEST_FLAG_CONN_SECURED;
    if (client->ssl_secured)
        req.flags |= MAIL_AUTH_REQUEST_FLAG_CONN_SSL_SECURED;
    memcpy(req.cookie, anvil_request->cookie, sizeof(req.cookie));

    buf = t_buffer_create(256);
    /* session ID */
    buffer_append(buf, session_id, strlen(session_id)+1);
    /* protocol specific data (e.g. IMAP tag) */
    buffer_append(buf, client->master_data_prefix,
              client->master_data_prefix_len);
    /* buffered client input */
    data = i_stream_get_data(client->input, &size);
    buffer_append(buf, data, size);
    req.data_size = buf->used;

    client->auth_finished = ioloop_time;
    client->master_auth_id = req.auth_id;

    i_zero(&params);
    params.client_fd = fd;
    params.socket_path = client->postlogin_socket_path;
    params.request = req;
    params.data = buf->data;
    master_auth_request_full(master_auth, &params, master_auth_callback,
                 client, &client->master_tag);
    if (close_fd)
        i_close_fd(&fd);
    return 0;
}

static void ATTR_NULL(1)
anvil_lookup_callback(const char *reply, void *context)
{
    struct anvil_request *req = context;
    struct client *client = req->client;
    const struct login_settings *set = client->set;
    const char *errmsg;
    unsigned int conn_count;
    int ret;

    conn_count = 0;
    if (reply != NULL && str_to_uint(reply, &conn_count) < 0)
        i_fatal("Received invalid reply from anvil: %s", reply);

    /* reply=NULL if we didn't need to do anvil lookup,
       or if the anvil lookup failed. allow failed anvil lookups in. */
    if (reply == NULL || conn_count < set->mail_max_userip_connections) {
        ret = master_send_request(req);
        errmsg = NULL; /* client will see internal error */
    } else {
        ret = -1;
        errmsg = t_strdup_printf(ERR_TOO_MANY_USERIP_CONNECTIONS,
                     set->mail_max_userip_connections);
    }
    if (ret < 0) {
        client->authenticating = FALSE;
        auth_client_send_cancel(auth_client, req->auth_id);
        call_client_callback(client, SASL_SERVER_REPLY_MASTER_FAILED,
                     errmsg, NULL);
    }
    i_free(req);
}

static void
anvil_check_too_many_connections(struct client *client,
                 struct auth_client_request *request)
{
    struct anvil_request *req;
    const char *query, *cookie;
    buffer_t buf;

    req = i_new(struct anvil_request, 1);
    req->client = client;
    req->auth_pid = auth_client_request_get_server_pid(request);
    req->auth_id = auth_client_request_get_id(request);

    buffer_create_from_data(&buf, req->cookie, sizeof(req->cookie));
    cookie = auth_client_request_get_cookie(request);
    if (strlen(cookie) == MASTER_AUTH_COOKIE_SIZE*2)
        (void)hex_to_binary(cookie, &buf);

    if (client->virtual_user == NULL ||
        client->set->mail_max_userip_connections == 0) {
        anvil_lookup_callback(NULL, req);
        return;
    }

    query = t_strconcat("LOOKUP\t", login_binary->protocol, "/",
                net_ip2addr(&client->ip), "/",
                str_tabescape(client->virtual_user), NULL);
    anvil_client_query(anvil, query, anvil_lookup_callback, req);
}

static void
authenticate_callback(struct auth_client_request *request,
              enum auth_request_status status, const char *data_base64,
              const char *const *args, void *context)
{
    struct client *client = context;
    unsigned int i;
    bool nologin;

    if (!client->authenticating) {
        /* client aborted */
        i_assert(status < 0);
        return;
    }
    client->auth_waiting = FALSE;

    i_assert(client->auth_request == request);
    switch (status) {
    case AUTH_REQUEST_STATUS_CONTINUE:
        /* continue */
        client->sasl_callback(client, SASL_SERVER_REPLY_CONTINUE,
                      data_base64, NULL);
        break;
    case AUTH_REQUEST_STATUS_OK:
        client->auth_request = NULL;
        client->auth_successes++;
        client->auth_passdb_args = p_strarray_dup(client->pool, args);
        client->postlogin_socket_path = NULL;

        nologin = FALSE;
        for (i = 0; args[i] != NULL; i++) {
            if (strncmp(args[i], "user=", 5) == 0) {
                i_free(client->virtual_user);
                i_free_and_null(client->virtual_user_orig);
                i_free_and_null(client->virtual_auth_user);
                client->virtual_user = i_strdup(args[i] + 5);
            } else if (strncmp(args[i], "original_user=", 14) == 0) {
                i_free(client->virtual_user_orig);
                client->virtual_user_orig = i_strdup(args[i] + 14);
            } else if (strncmp(args[i], "auth_user=", 10) == 0) {
                i_free(client->virtual_auth_user);
                client->virtual_auth_user =
                    i_strdup(args[i] + 10);
            } else if (strncmp(args[i], "postlogin_socket=", 17) == 0) {
                client->postlogin_socket_path =
                    p_strdup(client->pool, args[i] + 17);
            } else if (strcmp(args[i], "nologin") == 0 ||
                   strcmp(args[i], "proxy") == 0) {
                /* user can't login */
                nologin = TRUE;
            } else if (strncmp(args[i], "resp=", 5) == 0 &&
                   login_binary->sasl_support_final_reply) {
                client->sasl_final_resp =
                    p_strdup(client->pool, args[i] + 5);
            }
        }

        if (nologin) {
            client->authenticating = FALSE;
            call_client_callback(client, SASL_SERVER_REPLY_SUCCESS,
                         NULL, args);
        } else {
            anvil_check_too_many_connections(client, request);
        }
        break;
    case AUTH_REQUEST_STATUS_INTERNAL_FAIL:
        client->auth_process_comm_fail = TRUE;
        /* fall through */
    case AUTH_REQUEST_STATUS_FAIL:
    case AUTH_REQUEST_STATUS_ABORT:
        client->auth_request = NULL;

        if (args != NULL) {
            /* parse our username if it's there */
            for (i = 0; args[i] != NULL; i++) {
                if (strncmp(args[i], "user=", 5) == 0) {
                    i_free(client->virtual_user);
                    i_free_and_null(client->virtual_user_orig);
                    i_free_and_null(client->virtual_auth_user);
                    client->virtual_user =
                        i_strdup(args[i] + 5);
                } else if (strncmp(args[i], "original_user=", 14) == 0) {
                    i_free(client->virtual_user_orig);
                    client->virtual_user_orig =
                        i_strdup(args[i] + 14);
                } else if (strncmp(args[i], "auth_user=", 10) == 0) {
                    i_free(client->virtual_auth_user);
                    client->virtual_auth_user =
                        i_strdup(args[i] + 10);
                }
            }
        }

        client->authenticating = FALSE;
        call_client_callback(client, SASL_SERVER_REPLY_AUTH_FAILED,
                     NULL, args);
        break;
    }
}

void sasl_server_auth_begin(struct client *client,
                const char *service, const char *mech_name,
                const char *initial_resp_base64,
                sasl_server_callback_t *callback)
{
    struct auth_request_info info;
    const struct auth_mech_desc *mech;

    i_assert(auth_client_is_connected(auth_client));

    client->auth_attempts++;
    client->authenticating = TRUE;
    if (client->auth_first_started == 0)
        client->auth_first_started = ioloop_time;
    i_free(client->auth_mech_name);
    client->auth_mech_name = str_ucase(i_strdup(mech_name));
    client->sasl_callback = callback;

    mech = auth_client_find_mech(auth_client, mech_name);
    if (mech == NULL) {
        sasl_server_auth_failed(client,
            "Unsupported authentication mechanism.",
            AUTH_CLIENT_FAIL_CODE_MECH_INVALID);
        return;
    }

    if (!client->secured && client->set->disable_plaintext_auth &&
        (mech->flags & MECH_SEC_PLAINTEXT) != 0) {
        sasl_server_auth_failed(client,
            "Plaintext authentication disabled.",
             AUTH_CLIENT_FAIL_CODE_MECH_SSL_REQUIRED);
        return;
    }

    i_zero(&info);
    info.mech = mech->name;
    info.service = service;
    info.session_id = client_get_session_id(client);
    if (client->client_cert_common_name != NULL)
        info.cert_username = client->client_cert_common_name;
    else if (client->ssl_iostream != NULL)
        info.cert_username = ssl_iostream_get_peer_name(client->ssl_iostream);
    info.flags = client_get_auth_flags(client);
    info.local_ip = client->local_ip;
    info.remote_ip = client->ip;
    info.local_port = client->local_port;
    info.local_name = client->local_name;
    info.remote_port = client->remote_port;
    info.real_local_ip = client->real_local_ip;
    info.real_remote_ip = client->real_remote_ip;
    info.real_local_port = client->real_local_port;
    info.real_remote_port = client->real_remote_port;
    if (client->client_id != NULL)
        info.client_id = str_c(client->client_id);
    if (client->forward_fields != NULL)
        info.forward_fields = str_c(client->forward_fields);
    info.initial_resp_base64 = initial_resp_base64;

    client->auth_request =
        auth_client_request_new(auth_client, &info,
                    authenticate_callback, client);
}

static void ATTR_NULL(2, 3)
sasl_server_auth_cancel(struct client *client, const char *reason,
            const char *code, enum sasl_server_reply reply)
{
    i_assert(client->authenticating);

    if (client->set->auth_verbose && reason != NULL) {
        const char *auth_name =
            str_sanitize(client->auth_mech_name, MAX_MECH_NAME);
        client_log(client, t_strdup_printf(
            "Authenticate %s failed: %s", auth_name, reason));
    }

    client->authenticating = FALSE;
    if (client->auth_request != NULL)
        auth_client_request_abort(&client->auth_request);

    if (code != NULL) {
        const char *args[2];

        args[0] = t_strconcat("code=", code, NULL);
        args[1] = NULL;
        call_client_callback(client, reply, reason, args);
        return;
    }

    call_client_callback(client, reply, reason, NULL);
}

void sasl_server_auth_failed(struct client *client, const char *reason,
    const char *code)
{
    sasl_server_auth_cancel(client, reason, code, SASL_SERVER_REPLY_AUTH_FAILED);
}

void sasl_server_auth_abort(struct client *client)
{
    client->auth_try_aborted = TRUE;
    sasl_server_auth_cancel(client, NULL, NULL, SASL_SERVER_REPLY_AUTH_ABORTED);
}