auth.c

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/*
 * MUSCLE SmartCard Development ( https://pcsclite.apdu.fr/ )
 *
 * Copyright (C) 2013 Red Hat
 *
 * All rights reserved.
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 *
 * Author: Nikos Mavrogiannopoulos <nmav@redhat.com>
 */

#include "config.h"
#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/un.h>
#include <stdio.h>
#include "debuglog.h"
#include "auth.h"

#include <errno.h>

#ifdef HAVE_POLKIT

#if defined(SO_PEERCRED) || defined(LOCAL_PEERCRED)

#include <polkit/polkit.h>
#include <stdbool.h>

#ifdef __FreeBSD__

#include <sys/ucred.h>
typedef struct xucred platform_cred;
#define CRED_PID(uc)    (uc).cr_pid
#define CRED_UID(uc)    (uc).cr_uid

#else

typedef struct ucred platform_cred;
#define CRED_PID(uc)    (uc).pid
#define CRED_UID(uc)    (uc).uid

#endif

extern bool disable_polkit;

/* Returns non zero when the client is authorized */
unsigned IsClientAuthorized(int socket, const char* action, const char* reader)
{
    platform_cred cr;
    socklen_t cr_len;
    int ret;
    PolkitSubject *subject;
    PolkitAuthority *authority;
    PolkitAuthorizationResult *result;
    PolkitDetails *details;
    GError *error = NULL;
    char action_name[128];

    if (disable_polkit)
        return 1;

    snprintf(action_name, sizeof(action_name), "org.debian.pcsc-lite.%s", action);

    cr_len = sizeof(cr);
#ifdef LOCAL_PEERCRED
    ret = getsockopt(socket, SOL_LOCAL, LOCAL_PEERCRED, &cr, &cr_len);
#else
    ret = getsockopt(socket, SOL_SOCKET, SO_PEERCRED, &cr, &cr_len);
#endif
    if (ret == -1)
    {
#ifndef NO_LOG
        int e = errno;
        Log2(PCSC_LOG_CRITICAL,
             "Error obtaining client process credentials: %s", strerror(e));
#endif
        return 0;
    }

    authority = polkit_authority_get_sync(NULL, &error);
    if (authority == NULL)
    {
        Log2(PCSC_LOG_CRITICAL, "polkit_authority_get_sync failed: %s",
            error->message);
        g_error_free(error);
        return 0;
    }

    subject = polkit_unix_process_new_for_owner(CRED_PID(cr), 0, CRED_UID(cr));
    if (subject == NULL)
    {
        Log1(PCSC_LOG_CRITICAL, "polkit_unix_process_new_for_owner failed");
        ret = 0;
        goto cleanup1;
    }

    details = polkit_details_new();
    if (details == NULL)
    {
        Log1(PCSC_LOG_CRITICAL, "polkit_details_new failed");
        ret = 0;
        goto cleanup0;
    }

    if (reader != NULL)
        polkit_details_insert(details, "reader", reader);

    result = polkit_authority_check_authorization_sync(authority, subject,
        action_name, details,
        POLKIT_CHECK_AUTHORIZATION_FLAGS_ALLOW_USER_INTERACTION,
        NULL,
        &error);

    if (result == NULL)
    {
        Log2(PCSC_LOG_CRITICAL, "Error in authorization: %s", error->message);
        g_error_free(error);
        ret = 0;
    }
    else
    {
        if (polkit_authorization_result_get_is_authorized(result))
        {
            ret = 1;
        }
        else
        {
            ret = 0;
        }
    }

    if (ret == 0)
    {
        Log4(PCSC_LOG_CRITICAL,
             "Process %u (user: %u) is NOT authorized for action: %s",
            (unsigned)CRED_PID(cr), (unsigned)CRED_UID(cr), action);
    }

    if (result)
        g_object_unref(result);

    g_object_unref(subject);
cleanup0:
    g_object_unref(details);
cleanup1:
    g_object_unref(authority);

    while (g_main_context_pending(NULL))
        g_main_context_iteration(NULL, TRUE);

    return ret;
}

#else

/* Do not enable polkit if it not yet supported on your system.
 * Patches are welcome. */
#error polkit is enabled, but no socket cred implementation for this platform

#endif

#else

unsigned IsClientAuthorized(int socket, const char* action, const char* reader)
{
    (void)socket;
    (void)action;
    (void)reader;

    return 1;
}

#endif