sl@0: /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
sl@0:  * Portion Copyright © 2008 Nokia Corporation and/or its subsidiary(-ies). All rights reserved.
sl@0:  * selinux.c  SELinux security checks for D-Bus
sl@0:  *
sl@0:  * Author: Matthew Rickard <mjricka@epoch.ncsc.mil>
sl@0:  *
sl@0:  * Licensed under the Academic Free License version 2.1
sl@0:  * 
sl@0:  * This program is free software; you can redistribute it and/or modify
sl@0:  * it under the terms of the GNU General Public License as published by
sl@0:  * the Free Software Foundation; either version 2 of the License, or
sl@0:  * (at your option) any later version.
sl@0:  *
sl@0:  * This program is distributed in the hope that it will be useful,
sl@0:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
sl@0:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
sl@0:  * GNU General Public License for more details.
sl@0:  * 
sl@0:  * You should have received a copy of the GNU General Public License
sl@0:  * along with this program; if not, write to the Free Software
sl@0:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
sl@0:  *
sl@0:  */
sl@0: #ifndef __SYMBIAN32__
sl@0: #include <dbus/dbus-internals.h>
sl@0: #include <dbus/dbus-string.h>
sl@0: #else
sl@0: #include "dbus-internals.h"
sl@0: #include "dbus-string.h"
sl@0: #endif //__SYMBIAN32__
sl@0: #include "selinux.h"
sl@0: #include "services.h"
sl@0: #include "policy.h"
sl@0: #include "utils.h"
sl@0: #include "config-parser.h"
sl@0: 
sl@0: #ifdef HAVE_SELINUX
sl@0: #include <errno.h>
sl@0: #include <pthread.h>
sl@0: #include <syslog.h>
sl@0: #include <selinux/selinux.h>
sl@0: #include <selinux/avc.h>
sl@0: #include <selinux/av_permissions.h>
sl@0: #include <selinux/flask.h>
sl@0: #include <signal.h>
sl@0: #include <stdarg.h>
sl@0: #endif /* HAVE_SELINUX */
sl@0: 
sl@0: #define BUS_SID_FROM_SELINUX(sid)  ((BusSELinuxID*) (sid))
sl@0: #define SELINUX_SID_FROM_BUS(sid)  ((security_id_t) (sid))
sl@0: 
sl@0: #ifdef HAVE_SELINUX
sl@0: /* Store the value telling us if SELinux is enabled in the kernel. */
sl@0: static dbus_bool_t selinux_enabled = FALSE;
sl@0: 
sl@0: /* Store an avc_entry_ref to speed AVC decisions. */
sl@0: static struct avc_entry_ref aeref;
sl@0: 
sl@0: /* Store the SID of the bus itself to use as the default. */
sl@0: static security_id_t bus_sid = SECSID_WILD;
sl@0: 
sl@0: /* Thread to listen for SELinux status changes via netlink. */
sl@0: static pthread_t avc_notify_thread;
sl@0: 
sl@0: /* Prototypes for AVC callback functions.  */
sl@0: static void log_callback (const char *fmt, ...);
sl@0: static void log_audit_callback (void *data, security_class_t class, char *buf, size_t bufleft);
sl@0: static void *avc_create_thread (void (*run) (void));
sl@0: static void avc_stop_thread (void *thread);
sl@0: static void *avc_alloc_lock (void);
sl@0: static void avc_get_lock (void *lock);
sl@0: static void avc_release_lock (void *lock);
sl@0: static void avc_free_lock (void *lock);
sl@0: 
sl@0: /* AVC callback structures for use in avc_init.  */
sl@0: static const struct avc_memory_callback mem_cb =
sl@0: {
sl@0:   .func_malloc = dbus_malloc,
sl@0:   .func_free = dbus_free
sl@0: };
sl@0: static const struct avc_log_callback log_cb =
sl@0: {
sl@0:   .func_log = log_callback,
sl@0:   .func_audit = log_audit_callback
sl@0: };
sl@0: static const struct avc_thread_callback thread_cb =
sl@0: {
sl@0:   .func_create_thread = avc_create_thread,
sl@0:   .func_stop_thread = avc_stop_thread
sl@0: };
sl@0: static const struct avc_lock_callback lock_cb =
sl@0: {
sl@0:   .func_alloc_lock = avc_alloc_lock,
sl@0:   .func_get_lock = avc_get_lock,
sl@0:   .func_release_lock = avc_release_lock,
sl@0:   .func_free_lock = avc_free_lock
sl@0: };
sl@0: #endif /* HAVE_SELINUX */
sl@0: 
sl@0: /**
sl@0:  * Log callback to log denial messages from the AVC.
sl@0:  * This is used in avc_init.  Logs to both standard
sl@0:  * error and syslogd.
sl@0:  *
sl@0:  * @param fmt the format string
sl@0:  * @param variable argument list
sl@0:  */
sl@0: #ifdef HAVE_SELINUX
sl@0: static void 
sl@0: log_callback (const char *fmt, ...) 
sl@0: {
sl@0:   va_list ap;
sl@0:   va_start(ap, fmt);
sl@0:   vsyslog (LOG_INFO, fmt, ap);
sl@0:   va_end(ap);
sl@0: }
sl@0: 
sl@0: /**
sl@0:  * On a policy reload we need to reparse the SELinux configuration file, since
sl@0:  * this could have changed.  Send a SIGHUP to reload all configs.
sl@0:  */
sl@0: static int
sl@0: policy_reload_callback (u_int32_t event, security_id_t ssid, 
sl@0:                         security_id_t tsid, security_class_t tclass, 
sl@0:                         access_vector_t perms, access_vector_t *out_retained)
sl@0: {
sl@0:   if (event == AVC_CALLBACK_RESET)
sl@0:     return raise (SIGHUP);
sl@0:   
sl@0:   return 0;
sl@0: }
sl@0: 
sl@0: /**
sl@0:  * Log any auxiliary data 
sl@0:  */
sl@0: static void
sl@0: log_audit_callback (void *data, security_class_t class, char *buf, size_t bufleft)
sl@0: {
sl@0:   DBusString *audmsg = data;
sl@0:   _dbus_string_copy_to_buffer (audmsg, buf, bufleft);
sl@0: }
sl@0: 
sl@0: /**
sl@0:  * Create thread to notify the AVC of enforcing and policy reload
sl@0:  * changes via netlink.
sl@0:  *
sl@0:  * @param run the thread run function
sl@0:  * @return pointer to the thread
sl@0:  */
sl@0: static void *
sl@0: avc_create_thread (void (*run) (void))
sl@0: {
sl@0:   int rc;
sl@0: 
sl@0:   rc = pthread_create (&avc_notify_thread, NULL, (void *(*) (void *)) run, NULL);
sl@0:   if (rc != 0)
sl@0:     {
sl@0:       _dbus_warn ("Failed to start AVC thread: %s\n", _dbus_strerror (rc));
sl@0:       exit (1);
sl@0:     }
sl@0:   return &avc_notify_thread;
sl@0: }
sl@0: 
sl@0: /* Stop AVC netlink thread.  */
sl@0: static void
sl@0: avc_stop_thread (void *thread)
sl@0: {
sl@0:   pthread_cancel (*(pthread_t *) thread);
sl@0: }
sl@0: 
sl@0: /* Allocate a new AVC lock.  */
sl@0: static void *
sl@0: avc_alloc_lock (void)
sl@0: {
sl@0:   pthread_mutex_t *avc_mutex;
sl@0: 
sl@0:   avc_mutex = dbus_new (pthread_mutex_t, 1);
sl@0:   if (avc_mutex == NULL)
sl@0:     {
sl@0:       _dbus_warn ("Could not create mutex: %s\n", _dbus_strerror (errno));
sl@0:       exit (1);
sl@0:     }
sl@0:   pthread_mutex_init (avc_mutex, NULL);
sl@0: 
sl@0:   return avc_mutex;
sl@0: }
sl@0: 
sl@0: /* Acquire an AVC lock.  */
sl@0: static void
sl@0: avc_get_lock (void *lock)
sl@0: {
sl@0:   pthread_mutex_lock (lock);
sl@0: }
sl@0: 
sl@0: /* Release an AVC lock.  */
sl@0: static void
sl@0: avc_release_lock (void *lock)
sl@0: {
sl@0:   pthread_mutex_unlock (lock);
sl@0: }
sl@0: 
sl@0: /* Free an AVC lock.  */
sl@0: static void
sl@0: avc_free_lock (void *lock)
sl@0: {
sl@0:   pthread_mutex_destroy (lock);
sl@0:   dbus_free (lock);
sl@0: }
sl@0: #endif /* HAVE_SELINUX */
sl@0: 
sl@0: /**
sl@0:  * Return whether or not SELinux is enabled; must be
sl@0:  * called after bus_selinux_init.
sl@0:  */
sl@0: dbus_bool_t
sl@0: bus_selinux_enabled (void)
sl@0: {
sl@0: #ifdef HAVE_SELINUX
sl@0:   return selinux_enabled;
sl@0: #else
sl@0:   return FALSE;
sl@0: #endif /* HAVE_SELINUX */
sl@0: }
sl@0: 
sl@0: /**
sl@0:  * Do early initialization; determine whether SELinux is enabled.
sl@0:  */
sl@0: dbus_bool_t
sl@0: bus_selinux_pre_init (void)
sl@0: {
sl@0: #ifdef HAVE_SELINUX
sl@0:   int r;
sl@0:   _dbus_assert (bus_sid == SECSID_WILD);
sl@0:   
sl@0:   /* Determine if we are running an SELinux kernel. */
sl@0:   r = is_selinux_enabled ();
sl@0:   if (r < 0)
sl@0:     {
sl@0:       _dbus_warn ("Could not tell if SELinux is enabled: %s\n",
sl@0:                   _dbus_strerror (errno));
sl@0:       return FALSE;
sl@0:     }
sl@0: 
sl@0:   selinux_enabled = r != 0;
sl@0:   return TRUE;
sl@0: #else
sl@0:   return TRUE;
sl@0: #endif
sl@0: }
sl@0: 
sl@0: /**
sl@0:  * Initialize the user space access vector cache (AVC) for D-Bus and set up
sl@0:  * logging callbacks.
sl@0:  */
sl@0: dbus_bool_t
sl@0: bus_selinux_full_init (void)
sl@0: {
sl@0: #ifdef HAVE_SELINUX
sl@0:   char *bus_context;
sl@0: 
sl@0:   _dbus_assert (bus_sid == SECSID_WILD);
sl@0:   
sl@0:   if (!selinux_enabled)
sl@0:     {
sl@0:       _dbus_verbose ("SELinux not enabled in this kernel.\n");
sl@0:       return TRUE;
sl@0:     }
sl@0: 
sl@0:   _dbus_verbose ("SELinux is enabled in this kernel.\n");
sl@0: 
sl@0:   avc_entry_ref_init (&aeref);
sl@0:   if (avc_init ("avc", &mem_cb, &log_cb, &thread_cb, &lock_cb) < 0)
sl@0:     {
sl@0:       _dbus_warn ("Failed to start Access Vector Cache (AVC).\n");
sl@0:       return FALSE;
sl@0:     }
sl@0:   else
sl@0:     {
sl@0:       openlog ("dbus", LOG_PERROR, LOG_USER);
sl@0:       _dbus_verbose ("Access Vector Cache (AVC) started.\n");
sl@0:     }
sl@0: 
sl@0:   if (avc_add_callback (policy_reload_callback, AVC_CALLBACK_RESET,
sl@0:                        NULL, NULL, 0, 0) < 0)
sl@0:     {
sl@0:       _dbus_warn ("Failed to add policy reload callback: %s\n",
sl@0:                   _dbus_strerror (errno));
sl@0:       avc_destroy ();
sl@0:       return FALSE;
sl@0:     }
sl@0: 
sl@0:   bus_context = NULL;
sl@0:   bus_sid = SECSID_WILD;
sl@0: 
sl@0:   if (getcon (&bus_context) < 0)
sl@0:     {
sl@0:       _dbus_verbose ("Error getting context of bus: %s\n",
sl@0:                      _dbus_strerror (errno));
sl@0:       return FALSE;
sl@0:     }
sl@0:       
sl@0:   if (avc_context_to_sid (bus_context, &bus_sid) < 0)
sl@0:     {
sl@0:       _dbus_verbose ("Error getting SID from bus context: %s\n",
sl@0:                      _dbus_strerror (errno));
sl@0:       freecon (bus_context);
sl@0:       return FALSE;
sl@0:     }
sl@0: 
sl@0:   freecon (bus_context);
sl@0:   
sl@0:   return TRUE;
sl@0: #else
sl@0:   return TRUE;
sl@0: #endif /* HAVE_SELINUX */
sl@0: }
sl@0: 
sl@0: /**
sl@0:  * Decrement SID reference count.
sl@0:  * 
sl@0:  * @param sid the SID to decrement
sl@0:  */
sl@0: void
sl@0: bus_selinux_id_unref (BusSELinuxID *sid)
sl@0: {
sl@0: #ifdef HAVE_SELINUX
sl@0:   if (!selinux_enabled)
sl@0:     return;
sl@0: 
sl@0:   _dbus_assert (sid != NULL);
sl@0:   
sl@0:   sidput (SELINUX_SID_FROM_BUS (sid));
sl@0: #endif /* HAVE_SELINUX */
sl@0: }
sl@0: 
sl@0: void
sl@0: bus_selinux_id_ref (BusSELinuxID *sid)
sl@0: {
sl@0: #ifdef HAVE_SELINUX
sl@0:   if (!selinux_enabled)
sl@0:     return;
sl@0: 
sl@0:   _dbus_assert (sid != NULL);
sl@0:   
sl@0:   sidget (SELINUX_SID_FROM_BUS (sid));
sl@0: #endif /* HAVE_SELINUX */
sl@0: }
sl@0: 
sl@0: /**
sl@0:  * Determine if the SELinux security policy allows the given sender
sl@0:  * security context to go to the given recipient security context.
sl@0:  * This function determines if the requested permissions are to be
sl@0:  * granted from the connection to the message bus or to another
sl@0:  * optionally supplied security identifier (e.g. for a service
sl@0:  * context).  Currently these permissions are either send_msg or
sl@0:  * acquire_svc in the dbus class.
sl@0:  *
sl@0:  * @param sender_sid source security context
sl@0:  * @param override_sid is the target security context.  If SECSID_WILD this will
sl@0:  *        use the context of the bus itself (e.g. the default).
sl@0:  * @param target_class is the target security class.
sl@0:  * @param requested is the requested permissions.
sl@0:  * @returns #TRUE if security policy allows the send.
sl@0:  */
sl@0: #ifdef HAVE_SELINUX
sl@0: static dbus_bool_t
sl@0: bus_selinux_check (BusSELinuxID        *sender_sid,
sl@0:                    BusSELinuxID        *override_sid,
sl@0:                    security_class_t     target_class,
sl@0:                    access_vector_t      requested,
sl@0: 		   DBusString          *auxdata)
sl@0: {
sl@0:   if (!selinux_enabled)
sl@0:     return TRUE;
sl@0: 
sl@0:   /* Make the security check.  AVC checks enforcing mode here as well. */
sl@0:   if (avc_has_perm (SELINUX_SID_FROM_BUS (sender_sid),
sl@0:                     override_sid ?
sl@0:                     SELINUX_SID_FROM_BUS (override_sid) :
sl@0:                     SELINUX_SID_FROM_BUS (bus_sid), 
sl@0:                     target_class, requested, &aeref, auxdata) < 0)
sl@0:     {
sl@0:       _dbus_verbose ("SELinux denying due to security policy.\n");
sl@0:       return FALSE;
sl@0:     }
sl@0:   else
sl@0:     return TRUE;
sl@0: }
sl@0: #endif /* HAVE_SELINUX */
sl@0: 
sl@0: /**
sl@0:  * Returns true if the given connection can acquire a service,
sl@0:  * assuming the given security ID is needed for that service.
sl@0:  *
sl@0:  * @param connection connection that wants to own the service
sl@0:  * @param service_sid the SID of the service from the table
sl@0:  * @returns #TRUE if acquire is permitted.
sl@0:  */
sl@0: dbus_bool_t
sl@0: bus_selinux_allows_acquire_service (DBusConnection     *connection,
sl@0:                                     BusSELinuxID       *service_sid,
sl@0: 				    const char         *service_name,
sl@0: 				    DBusError          *error)
sl@0: {
sl@0: #ifdef HAVE_SELINUX
sl@0:   BusSELinuxID *connection_sid;
sl@0:   unsigned long spid;
sl@0:   DBusString auxdata;
sl@0:   dbus_bool_t ret;
sl@0:   
sl@0:   if (!selinux_enabled)
sl@0:     return TRUE;
sl@0:   
sl@0:   connection_sid = bus_connection_get_selinux_id (connection);
sl@0:   if (!dbus_connection_get_unix_process_id (connection, &spid))
sl@0:     spid = 0;
sl@0: 
sl@0:   if (!_dbus_string_init (&auxdata))
sl@0:     goto oom;
sl@0:  
sl@0:   if (!_dbus_string_append (&auxdata, "service="))
sl@0:     goto oom;
sl@0: 
sl@0:   if (!_dbus_string_append (&auxdata, service_name))
sl@0:     goto oom;
sl@0: 
sl@0:   if (spid)
sl@0:     {
sl@0:       if (!_dbus_string_append (&auxdata, " spid="))
sl@0: 	goto oom;
sl@0: 
sl@0:       if (!_dbus_string_append_uint (&auxdata, spid))
sl@0: 	goto oom;
sl@0:     }
sl@0:   
sl@0:   ret = bus_selinux_check (connection_sid,
sl@0: 			   service_sid,
sl@0: 			   SECCLASS_DBUS,
sl@0: 			   DBUS__ACQUIRE_SVC,
sl@0: 			   &auxdata);
sl@0: 
sl@0:   _dbus_string_free (&auxdata);
sl@0:   return ret;
sl@0: 
sl@0:  oom:
sl@0:   _dbus_string_free (&auxdata);
sl@0:   BUS_SET_OOM (error);
sl@0:   return FALSE;
sl@0: 
sl@0: #else
sl@0:   return TRUE;
sl@0: #endif /* HAVE_SELINUX */
sl@0: }
sl@0: 
sl@0: /**
sl@0:  * Check if SELinux security controls allow the message to be sent to a
sl@0:  * particular connection based on the security context of the sender and
sl@0:  * that of the receiver. The destination connection need not be the
sl@0:  * addressed recipient, it could be an "eavesdropper"
sl@0:  *
sl@0:  * @param sender the sender of the message.
sl@0:  * @param proposed_recipient the connection the message is to be sent to.
sl@0:  * @returns whether to allow the send
sl@0:  */
sl@0: dbus_bool_t
sl@0: bus_selinux_allows_send (DBusConnection     *sender,
sl@0:                          DBusConnection     *proposed_recipient,
sl@0: 			 const char         *msgtype,
sl@0: 			 const char         *interface,
sl@0: 			 const char         *member,
sl@0: 			 const char         *error_name,
sl@0: 			 const char         *destination,
sl@0: 			 DBusError          *error)
sl@0: {
sl@0: #ifdef HAVE_SELINUX
sl@0:   BusSELinuxID *recipient_sid;
sl@0:   BusSELinuxID *sender_sid;
sl@0:   unsigned long spid, tpid;
sl@0:   DBusString auxdata;
sl@0:   dbus_bool_t ret;
sl@0:   dbus_bool_t string_alloced;
sl@0: 
sl@0:   if (!selinux_enabled)
sl@0:     return TRUE;
sl@0: 
sl@0:   if (!sender || !dbus_connection_get_unix_process_id (sender, &spid))
sl@0:     spid = 0;
sl@0:   if (!proposed_recipient || !dbus_connection_get_unix_process_id (proposed_recipient, &tpid))
sl@0:     tpid = 0;
sl@0: 
sl@0:   string_alloced = FALSE;
sl@0:   if (!_dbus_string_init (&auxdata))
sl@0:     goto oom;
sl@0:   string_alloced = TRUE;
sl@0: 
sl@0:   if (!_dbus_string_append (&auxdata, "msgtype="))
sl@0:     goto oom;
sl@0: 
sl@0:   if (!_dbus_string_append (&auxdata, msgtype))
sl@0:     goto oom;
sl@0: 
sl@0:   if (interface)
sl@0:     {
sl@0:       if (!_dbus_string_append (&auxdata, " interface="))
sl@0: 	goto oom;
sl@0:       if (!_dbus_string_append (&auxdata, interface))
sl@0: 	goto oom;
sl@0:     }
sl@0: 
sl@0:   if (member)
sl@0:     {
sl@0:       if (!_dbus_string_append (&auxdata, " member="))
sl@0: 	goto oom;
sl@0:       if (!_dbus_string_append (&auxdata, member))
sl@0: 	goto oom;
sl@0:     }
sl@0: 
sl@0:   if (error_name)
sl@0:     {
sl@0:       if (!_dbus_string_append (&auxdata, " error_name="))
sl@0: 	goto oom;
sl@0:       if (!_dbus_string_append (&auxdata, error_name))
sl@0: 	goto oom;
sl@0:     }
sl@0: 
sl@0:   if (destination)
sl@0:     {
sl@0:       if (!_dbus_string_append (&auxdata, " dest="))
sl@0: 	goto oom;
sl@0:       if (!_dbus_string_append (&auxdata, destination))
sl@0: 	goto oom;
sl@0:     }
sl@0: 
sl@0:   if (spid)
sl@0:     {
sl@0:       if (!_dbus_string_append (&auxdata, " spid="))
sl@0: 	goto oom;
sl@0: 
sl@0:       if (!_dbus_string_append_uint (&auxdata, spid))
sl@0: 	goto oom;
sl@0:     }
sl@0: 
sl@0:   if (tpid)
sl@0:     {
sl@0:       if (!_dbus_string_append (&auxdata, " tpid="))
sl@0: 	goto oom;
sl@0: 
sl@0:       if (!_dbus_string_append_uint (&auxdata, tpid))
sl@0: 	goto oom;
sl@0:     }
sl@0: 
sl@0:   sender_sid = bus_connection_get_selinux_id (sender);
sl@0:   /* A NULL proposed_recipient means the bus itself. */
sl@0:   if (proposed_recipient)
sl@0:     recipient_sid = bus_connection_get_selinux_id (proposed_recipient);
sl@0:   else
sl@0:     recipient_sid = BUS_SID_FROM_SELINUX (bus_sid);
sl@0: 
sl@0:   ret = bus_selinux_check (sender_sid, 
sl@0: 			   recipient_sid,
sl@0: 			   SECCLASS_DBUS, 
sl@0: 			   DBUS__SEND_MSG,
sl@0: 			   &auxdata);
sl@0: 
sl@0:   _dbus_string_free (&auxdata);
sl@0: 
sl@0:   return ret;
sl@0: 
sl@0:  oom:
sl@0:   if (string_alloced)
sl@0:     _dbus_string_free (&auxdata);
sl@0:   BUS_SET_OOM (error);
sl@0:   return FALSE;
sl@0:   
sl@0: #else
sl@0:   return TRUE;
sl@0: #endif /* HAVE_SELINUX */
sl@0: }
sl@0: 
sl@0: dbus_bool_t
sl@0: bus_selinux_append_context (DBusMessage    *message,
sl@0: 			    BusSELinuxID   *sid,
sl@0: 			    DBusError      *error)
sl@0: {
sl@0: #ifdef HAVE_SELINUX
sl@0:   char *context;
sl@0: 
sl@0:   if (avc_sid_to_context (SELINUX_SID_FROM_BUS (sid), &context) < 0)
sl@0:     {
sl@0:       if (errno == ENOMEM)
sl@0:         BUS_SET_OOM (error);
sl@0:       else
sl@0:         dbus_set_error (error, DBUS_ERROR_FAILED,
sl@0:                         "Error getting context from SID: %s\n",
sl@0: 			_dbus_strerror (errno));
sl@0:       return FALSE;
sl@0:     }
sl@0:   if (!dbus_message_append_args (message,
sl@0: 				 DBUS_TYPE_ARRAY,
sl@0: 				 DBUS_TYPE_BYTE,
sl@0: 				 &context,
sl@0: 				 strlen (context),
sl@0: 				 DBUS_TYPE_INVALID))
sl@0:     {
sl@0:       _DBUS_SET_OOM (error);
sl@0:       return FALSE;
sl@0:     }
sl@0:   freecon (context);
sl@0:   return TRUE;
sl@0: #else
sl@0:   return TRUE;
sl@0: #endif
sl@0: }
sl@0: 
sl@0: /**
sl@0:  * Gets the security context of a connection to the bus. It is up to
sl@0:  * the caller to freecon() when they are done. 
sl@0:  *
sl@0:  * @param connection the connection to get the context of.
sl@0:  * @param con the location to store the security context.
sl@0:  * @returns #TRUE if context is successfully obtained.
sl@0:  */
sl@0: #ifdef HAVE_SELINUX
sl@0: static dbus_bool_t
sl@0: bus_connection_read_selinux_context (DBusConnection     *connection,
sl@0:                                      char              **con)
sl@0: {
sl@0:   int fd;
sl@0: 
sl@0:   if (!selinux_enabled)
sl@0:     return FALSE;
sl@0: 
sl@0:   _dbus_assert (connection != NULL);
sl@0:   
sl@0:   if (!dbus_connection_get_unix_fd (connection, &fd))
sl@0:     {
sl@0:       _dbus_verbose ("Failed to get file descriptor of socket.\n");
sl@0:       return FALSE;
sl@0:     }
sl@0:   
sl@0:   if (getpeercon (fd, con) < 0)
sl@0:     {
sl@0:       _dbus_verbose ("Error getting context of socket peer: %s\n",
sl@0:                      _dbus_strerror (errno));
sl@0:       return FALSE;
sl@0:     }
sl@0:   
sl@0:   _dbus_verbose ("Successfully read connection context.\n");
sl@0:   return TRUE;
sl@0: }
sl@0: #endif /* HAVE_SELINUX */
sl@0: 
sl@0: /**
sl@0:  * Read the SELinux ID from the connection.
sl@0:  *
sl@0:  * @param connection the connection to read from
sl@0:  * @returns the SID if successfully determined, #NULL otherwise.
sl@0:  */
sl@0: BusSELinuxID*
sl@0: bus_selinux_init_connection_id (DBusConnection *connection,
sl@0:                                 DBusError      *error)
sl@0: {
sl@0: #ifdef HAVE_SELINUX
sl@0:   char *con;
sl@0:   security_id_t sid;
sl@0:   
sl@0:   if (!selinux_enabled)
sl@0:     return NULL;
sl@0: 
sl@0:   if (!bus_connection_read_selinux_context (connection, &con))
sl@0:     {
sl@0:       dbus_set_error (error, DBUS_ERROR_FAILED,
sl@0:                       "Failed to read an SELinux context from connection");
sl@0:       _dbus_verbose ("Error getting peer context.\n");
sl@0:       return NULL;
sl@0:     }
sl@0: 
sl@0:   _dbus_verbose ("Converting context to SID to store on connection\n");
sl@0: 
sl@0:   if (avc_context_to_sid (con, &sid) < 0)
sl@0:     {
sl@0:       if (errno == ENOMEM)
sl@0:         BUS_SET_OOM (error);
sl@0:       else
sl@0:         dbus_set_error (error, DBUS_ERROR_FAILED,
sl@0:                         "Error getting SID from context \"%s\": %s\n",
sl@0: 			con, _dbus_strerror (errno));
sl@0:       
sl@0:       _dbus_warn ("Error getting SID from context \"%s\": %s\n",
sl@0: 		  con, _dbus_strerror (errno));
sl@0:       
sl@0:       freecon (con);
sl@0:       return NULL;
sl@0:     }
sl@0:  
sl@0:   freecon (con); 
sl@0:   return BUS_SID_FROM_SELINUX (sid);
sl@0: #else
sl@0:   return NULL;
sl@0: #endif /* HAVE_SELINUX */
sl@0: }
sl@0: 
sl@0: 
sl@0: /**
sl@0:  * Function for freeing hash table data.  These SIDs
sl@0:  * should no longer be referenced.
sl@0:  */
sl@0: static void
sl@0: bus_selinux_id_table_free_value (BusSELinuxID *sid)
sl@0: {
sl@0: #ifdef HAVE_SELINUX
sl@0:   /* NULL sometimes due to how DBusHashTable works */
sl@0:   if (sid)
sl@0:     bus_selinux_id_unref (sid);
sl@0: #endif /* HAVE_SELINUX */
sl@0: }
sl@0: 
sl@0: /**
sl@0:  * Creates a new table mapping service names to security ID.
sl@0:  * A security ID is a "compiled" security context, a security
sl@0:  * context is just a string.
sl@0:  *
sl@0:  * @returns the new table or #NULL if no memory
sl@0:  */
sl@0: DBusHashTable*
sl@0: bus_selinux_id_table_new (void)
sl@0: {
sl@0:   return _dbus_hash_table_new (DBUS_HASH_STRING,
sl@0:                                (DBusFreeFunction) dbus_free,
sl@0:                                (DBusFreeFunction) bus_selinux_id_table_free_value);
sl@0: }
sl@0: 
sl@0: /** 
sl@0:  * Hashes a service name and service context into the service SID
sl@0:  * table as a string and a SID.
sl@0:  *
sl@0:  * @param service_name is the name of the service.
sl@0:  * @param service_context is the context of the service.
sl@0:  * @param service_table is the table to hash them into.
sl@0:  * @return #FALSE if not enough memory
sl@0:  */
sl@0: dbus_bool_t
sl@0: bus_selinux_id_table_insert (DBusHashTable *service_table,
sl@0:                              const char    *service_name,
sl@0:                              const char    *service_context)
sl@0: {
sl@0: #ifdef HAVE_SELINUX
sl@0:   dbus_bool_t retval;
sl@0:   security_id_t sid;
sl@0:   char *key;
sl@0: 
sl@0:   if (!selinux_enabled)
sl@0:     return TRUE;
sl@0: 
sl@0:   sid = SECSID_WILD;
sl@0:   retval = FALSE;
sl@0: 
sl@0:   key = _dbus_strdup (service_name);
sl@0:   if (key == NULL)
sl@0:     return retval;
sl@0:   
sl@0:   if (avc_context_to_sid ((char *) service_context, &sid) < 0)
sl@0:     {
sl@0:       if (errno == ENOMEM)
sl@0:         {
sl@0: 	  dbus_free (key);
sl@0:           return FALSE;
sl@0: 	}
sl@0: 
sl@0:       _dbus_warn ("Error getting SID from context \"%s\": %s\n",
sl@0: 		  (char *) service_context,
sl@0:                   _dbus_strerror (errno));
sl@0:       goto out;
sl@0:     }
sl@0: 
sl@0:   if (!_dbus_hash_table_insert_string (service_table,
sl@0:                                        key,
sl@0:                                        BUS_SID_FROM_SELINUX (sid)))
sl@0:     goto out;
sl@0: 
sl@0:   _dbus_verbose ("Parsed \tservice: %s \n\t\tcontext: %s\n",
sl@0:                   key, 
sl@0:                   sid->ctx);
sl@0: 
sl@0:   /* These are owned by the hash, so clear them to avoid unref */
sl@0:   key = NULL;
sl@0:   sid = SECSID_WILD;
sl@0: 
sl@0:   retval = TRUE;
sl@0:   
sl@0:  out:
sl@0:   if (sid != SECSID_WILD)
sl@0:     sidput (sid);
sl@0: 
sl@0:   if (key)
sl@0:     dbus_free (key);
sl@0: 
sl@0:   return retval;
sl@0: #else
sl@0:   return TRUE;
sl@0: #endif /* HAVE_SELINUX */
sl@0: }
sl@0: 
sl@0: 
sl@0: /**
sl@0:  * Find the security identifier associated with a particular service
sl@0:  * name.  Return a pointer to this SID, or #NULL/SECSID_WILD if the
sl@0:  * service is not found in the hash table.  This should be nearly a
sl@0:  * constant time operation.  If SELinux support is not available,
sl@0:  * always return NULL.
sl@0:  *
sl@0:  * @param service_table the hash table to check for service name.
sl@0:  * @param service_name the name of the service to look for.
sl@0:  * @returns the SELinux ID associated with the service
sl@0:  */
sl@0: BusSELinuxID*
sl@0: bus_selinux_id_table_lookup (DBusHashTable    *service_table,
sl@0:                              const DBusString *service_name)
sl@0: {
sl@0: #ifdef HAVE_SELINUX
sl@0:   security_id_t sid;
sl@0: 
sl@0:   sid = SECSID_WILD;     /* default context */
sl@0: 
sl@0:   if (!selinux_enabled)
sl@0:     return NULL;
sl@0:   
sl@0:   _dbus_verbose ("Looking up service SID for %s\n",
sl@0:                  _dbus_string_get_const_data (service_name));
sl@0: 
sl@0:   sid = _dbus_hash_table_lookup_string (service_table,
sl@0:                                         _dbus_string_get_const_data (service_name));
sl@0: 
sl@0:   if (sid == SECSID_WILD)
sl@0:     _dbus_verbose ("Service %s not found\n", 
sl@0:                    _dbus_string_get_const_data (service_name));
sl@0:   else
sl@0:     _dbus_verbose ("Service %s found\n", 
sl@0:                    _dbus_string_get_const_data (service_name));
sl@0: 
sl@0:   return BUS_SID_FROM_SELINUX (sid);
sl@0: #endif /* HAVE_SELINUX */
sl@0:   return NULL;
sl@0: }
sl@0: 
sl@0: /**
sl@0:  * Get the SELinux policy root.  This is used to find the D-Bus
sl@0:  * specific config file within the policy.
sl@0:  */
sl@0: const char *
sl@0: bus_selinux_get_policy_root (void)
sl@0: {
sl@0: #ifdef HAVE_SELINUX
sl@0:   return selinux_policy_root ();
sl@0: #else
sl@0:   return NULL;
sl@0: #endif /* HAVE_SELINUX */
sl@0: } 
sl@0: 
sl@0: /**
sl@0:  * For debugging:  Print out the current hash table of service SIDs.
sl@0:  */
sl@0: void
sl@0: bus_selinux_id_table_print (DBusHashTable *service_table)
sl@0: {
sl@0: #ifdef DBUS_ENABLE_VERBOSE_MODE
sl@0: #ifdef HAVE_SELINUX
sl@0:   DBusHashIter iter;
sl@0: 
sl@0:   if (!selinux_enabled)
sl@0:     return;
sl@0:   
sl@0:   _dbus_verbose ("Service SID Table:\n");
sl@0:   _dbus_hash_iter_init (service_table, &iter);
sl@0:   while (_dbus_hash_iter_next (&iter))
sl@0:     {
sl@0:       const char *key = _dbus_hash_iter_get_string_key (&iter);
sl@0:       security_id_t sid = _dbus_hash_iter_get_value (&iter);
sl@0:       _dbus_verbose ("The key is %s\n", key);
sl@0:       _dbus_verbose ("The context is %s\n", sid->ctx);
sl@0:       _dbus_verbose ("The refcount is %d\n", sid->refcnt);
sl@0:     }
sl@0: #endif /* HAVE_SELINUX */
sl@0: #endif /* DBUS_ENABLE_VERBOSE_MODE */
sl@0: }
sl@0: 
sl@0: 
sl@0: #ifdef DBUS_ENABLE_VERBOSE_MODE
sl@0: #ifdef HAVE_SELINUX
sl@0: /**
sl@0:  * Print out some AVC statistics.
sl@0:  */
sl@0: static void
sl@0: bus_avc_print_stats (void)
sl@0: {
sl@0:   struct avc_cache_stats cstats;
sl@0: 
sl@0:   if (!selinux_enabled)
sl@0:     return;
sl@0:   
sl@0:   _dbus_verbose ("AVC Statistics:\n");
sl@0:   avc_cache_stats (&cstats);
sl@0:   avc_av_stats ();
sl@0:   _dbus_verbose ("AVC Cache Statistics:\n");
sl@0:   _dbus_verbose ("Entry lookups: %d\n", cstats.entry_lookups);
sl@0:   _dbus_verbose ("Entry hits: %d\n", cstats.entry_hits);
sl@0:   _dbus_verbose ("Entry misses %d\n", cstats.entry_misses);
sl@0:   _dbus_verbose ("Entry discards: %d\n", cstats.entry_discards);
sl@0:   _dbus_verbose ("CAV lookups: %d\n", cstats.cav_lookups);
sl@0:   _dbus_verbose ("CAV hits: %d\n", cstats.cav_hits);
sl@0:   _dbus_verbose ("CAV probes: %d\n", cstats.cav_probes);
sl@0:   _dbus_verbose ("CAV misses: %d\n", cstats.cav_misses);
sl@0: }
sl@0: #endif /* HAVE_SELINUX */
sl@0: #endif /* DBUS_ENABLE_VERBOSE_MODE */
sl@0: 
sl@0: 
sl@0: /**
sl@0:  * Destroy the AVC before we terminate.
sl@0:  */
sl@0: void
sl@0: bus_selinux_shutdown (void)
sl@0: {
sl@0: #ifdef HAVE_SELINUX
sl@0:   if (!selinux_enabled)
sl@0:     return;
sl@0: 
sl@0:   _dbus_verbose ("AVC shutdown\n");
sl@0: 
sl@0:   if (bus_sid != SECSID_WILD)
sl@0:     {
sl@0:       sidput (bus_sid);
sl@0:       bus_sid = SECSID_WILD;
sl@0:       
sl@0: #ifdef DBUS_ENABLE_VERBOSE_MODE
sl@0:       bus_avc_print_stats ();
sl@0: #endif /* DBUS_ENABLE_VERBOSE_MODE */
sl@0: 
sl@0:       avc_destroy ();
sl@0:     }
sl@0: #endif /* HAVE_SELINUX */
sl@0: }
sl@0: