src/login-common/sasl-server.c

	sasl-server.c revision 3ffb7fd86484c474b42f3f1e981ab0f7168b5df9
/* Copyright (c) 2002-2009 Dovecot authors, see the included COPYING file */

#include "common.h"
#include "base64.h"
#include "buffer.h"
#include "istream.h"
#include "write-full.h"
#include "strescape.h"
#include "str-sanitize.h"
#include "auth-client.h"
#include "ssl-proxy.h"
#include "master-service.h"
#include "master-interface.h"
#include "master-auth.h"
#include "client-common.h"

#include <stdlib.h>
#include <unistd.h>

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

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) {
        *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_proxy != NULL &&
        ssl_proxy_has_valid_client_cert(client->ssl_proxy))
        auth_flags |= AUTH_REQUEST_FLAG_VALID_CLIENT_CERT;
    if (client->secured)
        auth_flags |= AUTH_REQUEST_FLAG_SECURED;
    return auth_flags;
}

static void
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;
    switch (reply->status) {
    case MASTER_AUTH_STATUS_OK:
        sasl_reply = SASL_SERVER_REPLY_SUCCESS;
        break;
    case MASTER_AUTH_STATUS_INTERNAL_ERROR:
        break;
    }
    client->mail_pid = reply->mail_pid;
    call_client_callback(client, sasl_reply, data, NULL);
}

static void
master_send_request(struct client *client, struct auth_request *request)
{
    struct master_auth_request req;
    const unsigned char *data;
    size_t size;
    buffer_t *buf;

    memset(&req, 0, sizeof(req));
    req.auth_pid = auth_client_request_get_server_pid(request);
    req.auth_id = auth_client_request_get_id(request);
    req.local_ip = client->local_ip;
    req.remote_ip = client->ip;

    buf = buffer_create_dynamic(pool_datastack_create(), 256);
    buffer_append(buf, client->master_data_prefix,
              client->master_data_prefix_len);

    data = i_stream_get_data(client->input, &size);
    buffer_append(buf, data, size);
    req.data_size = buf->used;

    client->master_tag =
        master_auth_request(master_service, client->fd, &req, buf->data,
                    master_auth_callback, client);
}

static bool anvil_has_too_many_connections(struct client *client)
{
    const char *ident;
    char buf[64];
    ssize_t ret;

    if (client->virtual_user == NULL)
        return FALSE;
    if (client->set->mail_max_userip_connections == 0)
        return FALSE;

    ident = t_strconcat("LOOKUP\t", net_ip2addr(&client->ip), "/",
                str_tabescape(client->virtual_user), "/",
                login_protocol, "\n", NULL);
    if (write_full(anvil_fd, ident, strlen(ident)) < 0) {
        if (errno == EPIPE) {
            /* anvil process was probably recreated, don't bother
               logging an error about losing connection to it */
            return FALSE;
        }
        i_fatal("write(anvil) failed: %m");
    }
    ret = read(anvil_fd, buf, sizeof(buf)-1);
    if (ret < 0)
        i_fatal("read(anvil) failed: %m");
    else if (ret == 0)
        i_fatal("read(anvil) failed: EOF");
    if (buf[ret-1] != '\n')
        i_fatal("anvil lookup failed: Invalid input in reply");
    buf[ret-1] = '\0';

    return strtoul(buf, NULL, 10) >=
        client->set->mail_max_userip_connections;
}

static void authenticate_callback(struct auth_request *request, int 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;
    }

    i_assert(client->auth_request == request);
    switch (status) {
    case 0:
        /* continue */
        client->sasl_callback(client, SASL_SERVER_REPLY_CONTINUE,
                      data_base64, NULL);
        break;
    case 1:
        client->auth_request = NULL;

        nologin = FALSE;
        for (i = 0; args[i] != NULL; i++) {
            if (strncmp(args[i], "user=", 5) == 0) {
                i_free(client->virtual_user);
                client->virtual_user = i_strdup(args[i] + 5);
            }
            if (strcmp(args[i], "nologin") == 0 ||
                strcmp(args[i], "proxy") == 0) {
                /* user can't login */
                nologin = TRUE;
            }
        }

        if (nologin) {
            client->authenticating = FALSE;
            call_client_callback(client, SASL_SERVER_REPLY_SUCCESS,
                         NULL, args);
        } else if (anvil_has_too_many_connections(client)) {
            client->authenticating = FALSE;
            call_client_callback(client,
                    SASL_SERVER_REPLY_MASTER_FAILED,
                    ERR_TOO_MANY_USERIP_CONNECTIONS, NULL);
        } else {
            master_send_request(client, request);
        }
        break;
    case -1:
        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);
                    client->virtual_user =
                        i_strdup(args[i] + 5);
                }
            }
        }

        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;
    const char *error;

    client->auth_attempts++;
    client->authenticating = TRUE;
    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) {
        client->auth_tried_unsupported_mech = TRUE;
        sasl_server_auth_failed(client,
            "Unsupported authentication mechanism.");
        return;
    }

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

    memset(&info, 0, sizeof(info));
    info.mech = mech->name;
    info.service = service;
    info.cert_username = client->ssl_proxy == NULL ? NULL :
        ssl_proxy_get_peer_name(client->ssl_proxy);
    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.remote_port = client->remote_port;
    info.initial_resp_base64 = initial_resp_base64;

    client->auth_request =
        auth_client_request_new(auth_client, NULL, &info,
                    authenticate_callback, client, &error);
    if (client->auth_request == NULL) {
        sasl_server_auth_failed(client,
             t_strconcat("Authentication failed: ", error, NULL));
    }
}

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

    if (client->set->verbose_auth && 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);
        client->auth_request = NULL;
    }

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

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

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