path: root/dbus/dbus-credentials.c

/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/* dbus-credentials.c Credentials provable through authentication
 *
 * Copyright (C) 2007 Red Hat Inc.
 *
 * Licensed under the Academic Free License version 2.1
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */
#include <config.h>
#include <string.h>
#include "dbus-credentials.h"
#include "dbus-internals.h"

/**
 * @defgroup DBusCredentials Credentials provable through authentication
 * @ingroup  DBusInternals
 * @brief DBusCredentials object
 *
 * Credentials are what you have to prove you have in order to
 * authenticate.  The main credentials right now are a unix user
 * account, a Windows user account, or a UNIX process ID.
 */

/**
 * @defgroup DBusCredentialsInternals Credentials implementation details
 * @ingroup  DBusInternals
 * @brief DBusCredentials implementation details
 *
 * Private details of credentials code.
 *
 * @{
 */

struct DBusCredentials {
  int refcount;
  dbus_uid_t unix_uid;
  dbus_pid_t unix_pid;
  char *windows_sid;
};

/** @} */

/**
 * @addtogroup DBusCredentials
 * @{
 */

/**
 * Creates a new credentials object.
 *
 * @returns the new object or #NULL if no memory
 */
DBusCredentials*
_dbus_credentials_new (void)
{
  DBusCredentials *creds;

  creds = dbus_new (DBusCredentials, 1);
  if (creds == NULL)
    return NULL;
  
  creds->refcount = 1;
  creds->unix_uid = DBUS_UID_UNSET;
  creds->unix_pid = DBUS_PID_UNSET;
  creds->windows_sid = NULL;

  return creds;
}

/**
 * Creates a new object with credentials (user ID and process ID) from the current process.
 * @returns the new object or #NULL if no memory
 */
DBusCredentials*
_dbus_credentials_new_from_current_process (void)
{
  DBusCredentials *creds;

  creds = _dbus_credentials_new ();
  if (creds == NULL)
    return NULL;

  if (!_dbus_credentials_add_from_current_process (creds))
    {
      _dbus_credentials_unref (creds);
      return NULL;
    }
  
  return creds;
}

/**
 * Increment refcount on credentials.
 *
 * @param credentials the object
 */
void
_dbus_credentials_ref (DBusCredentials *credentials)
{
  _dbus_assert (credentials->refcount > 0);
  credentials->refcount += 1;
}

/**
 * Decrement refcount on credentials.
 *
 * @param credentials the object
 */
void
_dbus_credentials_unref (DBusCredentials    *credentials)
{
  _dbus_assert (credentials->refcount > 0);

  credentials->refcount -= 1;
  if (credentials->refcount == 0)
    {
      dbus_free (credentials->windows_sid);
      dbus_free (credentials);
    }
}

/**
 * Add a UNIX process ID to the credentials.
 *
 * @param credentials the object
 * @param pid the process ID
 * @returns #FALSE if no memory
 */
dbus_bool_t
_dbus_credentials_add_unix_pid (DBusCredentials    *credentials,
                                dbus_pid_t          pid)
{
  credentials->unix_pid = pid;
  return TRUE;
}

/**
 * Add a UNIX user ID to the credentials.
 *
 * @param credentials the object
 * @param uid the user ID
 * @returns #FALSE if no memory
 */
dbus_bool_t
_dbus_credentials_add_unix_uid(DBusCredentials    *credentials,
                               dbus_uid_t          uid)
{
  credentials->unix_uid = uid;
  return TRUE;

}

/**
 * Add a Windows user SID to the credentials.
 *
 * @param credentials the object
 * @param windows_sid the user SID
 * @returns #FALSE if no memory
 */
dbus_bool_t
_dbus_credentials_add_windows_sid (DBusCredentials    *credentials,
                                   const char         *windows_sid)
{
  char *copy;

  copy = _dbus_strdup (windows_sid);
  if (copy == NULL)
    return FALSE;

  dbus_free (credentials->windows_sid);
  credentials->windows_sid = copy;

  return TRUE;
}

/**
 * Checks whether the given credential is present.
 *
 * @param credentials the object
 * @param type the credential to check for
 * @returns #TRUE if the credential is present
 */
dbus_bool_t
_dbus_credentials_include (DBusCredentials    *credentials,
                           DBusCredentialType  type)
{
  switch (type)
    {
    case DBUS_CREDENTIAL_UNIX_PROCESS_ID:
      return credentials->unix_pid != DBUS_PID_UNSET;
    case DBUS_CREDENTIAL_UNIX_USER_ID:
      return credentials->unix_uid != DBUS_UID_UNSET;
    case DBUS_CREDENTIAL_WINDOWS_SID:
      return credentials->windows_sid != NULL;
    }

  _dbus_assert_not_reached ("Unknown credential enum value");
  return FALSE;
}

/**
 * Gets the UNIX process ID in the credentials, or #DBUS_PID_UNSET if
 * the credentials object doesn't contain a process ID.
 *
 * @param credentials the object
 * @returns UNIX process ID
 */
dbus_pid_t
_dbus_credentials_get_unix_pid (DBusCredentials    *credentials)
{
  return credentials->unix_pid;
}

/**
 * Gets the UNIX user ID in the credentials, or #DBUS_UID_UNSET if
 * the credentials object doesn't contain a user ID.
 *
 * @param credentials the object
 * @returns UNIX user ID
 */
dbus_uid_t
_dbus_credentials_get_unix_uid (DBusCredentials    *credentials)
{
  return credentials->unix_uid;
}

/**
 * Gets the Windows user SID in the credentials, or #NULL if
 * the credentials object doesn't contain a Windows user SID.
 *
 * @param credentials the object
 * @returns Windows user SID
 */
const char*
_dbus_credentials_get_windows_sid (DBusCredentials    *credentials)
{
  return credentials->windows_sid;
}

/**
 * Checks whether the first credentials object contains
 * all the credentials found in the second credentials object.
 *
 * @param credentials the object
 * @param possible_subset see if credentials in here are also in the first arg
 * @returns #TRUE if second arg is contained in first
 */
dbus_bool_t
_dbus_credentials_are_superset (DBusCredentials    *credentials,
                                DBusCredentials    *possible_subset)
{
  return
    (possible_subset->unix_pid == DBUS_PID_UNSET ||
     possible_subset->unix_pid == credentials->unix_pid) &&
    (possible_subset->unix_uid == DBUS_UID_UNSET ||
     possible_subset->unix_uid == credentials->unix_uid) &&
    (possible_subset->windows_sid == NULL ||
     (credentials->windows_sid && strcmp (possible_subset->windows_sid,
                                          credentials->windows_sid) == 0));
}

/**
 * Checks whether a credentials object contains anything.
 * 
 * @param credentials the object
 * @returns #TRUE if there are no credentials in the object
 */
dbus_bool_t
_dbus_credentials_are_empty (DBusCredentials    *credentials)
{
  return
    credentials->unix_pid == DBUS_PID_UNSET &&
    credentials->unix_uid == DBUS_UID_UNSET &&
    credentials->windows_sid == NULL;
}

/**
 * Checks whether a credentials object contains a user identity.
 * 
 * @param credentials the object
 * @returns #TRUE if there are no user identities in the object
 */
dbus_bool_t
_dbus_credentials_are_anonymous (DBusCredentials    *credentials)
{
  return
    credentials->unix_uid == DBUS_UID_UNSET &&
    credentials->windows_sid == NULL;
}

/**
 * Merge all credentials found in the second object into the first object,
 * overwriting the first object if there are any overlaps.
 * 
 * @param credentials the object
 * @param other_credentials credentials to merge
 * @returns #FALSE if no memory
 */
dbus_bool_t
_dbus_credentials_add_credentials (DBusCredentials    *credentials,
                                   DBusCredentials    *other_credentials)
{
  return
    _dbus_credentials_add_credential (credentials,
                                      DBUS_CREDENTIAL_UNIX_PROCESS_ID,
                                      other_credentials) &&
    _dbus_credentials_add_credential (credentials,
                                      DBUS_CREDENTIAL_UNIX_USER_ID,
                                      other_credentials) &&
    _dbus_credentials_add_credential (credentials,
                                      DBUS_CREDENTIAL_WINDOWS_SID,
                                      other_credentials);
}

/**
 * Merge the given credential found in the second object into the first object,
 * overwriting the first object's value for that credential.
 *
 * Does nothing if the second object does not contain the specified credential.
 * i.e., will never delete a credential from the first object.
 * 
 * @param credentials the object
 * @param which the credential to overwrite
 * @param other_credentials credentials to merge
 * @returns #FALSE if no memory
 */
dbus_bool_t
_dbus_credentials_add_credential (DBusCredentials    *credentials,
                                  DBusCredentialType  which,
                                  DBusCredentials    *other_credentials)
{
  if (which == DBUS_CREDENTIAL_UNIX_PROCESS_ID &&
      other_credentials->unix_pid != DBUS_PID_UNSET)
    {
      if (!_dbus_credentials_add_unix_pid (credentials, other_credentials->unix_pid))
        return FALSE;
    }
  else if (which == DBUS_CREDENTIAL_UNIX_USER_ID &&
           other_credentials->unix_uid != DBUS_UID_UNSET)
    {
      if (!_dbus_credentials_add_unix_uid (credentials, other_credentials->unix_uid))
        return FALSE;
    }
  else if (which == DBUS_CREDENTIAL_WINDOWS_SID &&
           other_credentials->windows_sid != NULL)
    {
      if (!_dbus_credentials_add_windows_sid (credentials, other_credentials->windows_sid))
        return FALSE;
    }

  return TRUE;
}

/**
 * Clear all credentials in the object.
 * 
 * @param credentials the object
 */
void
_dbus_credentials_clear (DBusCredentials    *credentials)
{
  credentials->unix_pid = DBUS_PID_UNSET;
  credentials->unix_uid = DBUS_UID_UNSET;
  dbus_free (credentials->windows_sid);
  credentials->windows_sid = NULL;
}

/**
 * Copy a credentials object.
 * 
 * @param credentials the object
 * @returns the copy or #NULL
 */
DBusCredentials*
_dbus_credentials_copy (DBusCredentials    *credentials)
{
  DBusCredentials *copy;

  copy = _dbus_credentials_new ();
  if (copy == NULL)
    return NULL;

  if (!_dbus_credentials_add_credentials (copy, credentials))
    {
      _dbus_credentials_unref (copy);
      return NULL;
    }

  return copy;
}

/**
 * Check whether the user-identifying credentials in two credentials
 * objects are identical. Credentials that are not related to the
 * user are ignored, but any kind of user ID credentials must be the
 * same (UNIX user ID, Windows user SID, etc.) and present in both
 * objects for the function to return #TRUE.
 * 
 * @param credentials the object
 * @param other_credentials credentials to compare
 * @returns #TRUE if the two credentials refer to the same user
 */
dbus_bool_t
_dbus_credentials_same_user (DBusCredentials    *credentials,
                             DBusCredentials    *other_credentials)
{
  /* both windows and unix user must be the same (though pretty much
   * in all conceivable cases, one will be unset)
   */
  return credentials->unix_uid == other_credentials->unix_uid &&
    ((!(credentials->windows_sid || other_credentials->windows_sid)) ||
     (credentials->windows_sid && other_credentials->windows_sid &&
      strcmp (credentials->windows_sid, other_credentials->windows_sid) == 0));
}

/** @} */

/* tests in dbus-credentials-util.c */