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dbus/test/internals/dbus-credentials-util.c
Luca Boccassi 80d523dcc8 DBusCredentials: add support for PID FDs via SO_PEERPIDFD 
The new socket option SO_PEERPIDFD allows to pin the process on the
other side of the socket by file descriptor, which closes a race
condition where a PID can be reused before we can pin it manually.
Available since Linux v6.5.

When storing credentials, pin the process by FD from the PID.
When querying the PID, if the PID FD is available, resolve
it from there first if possible.

Ensure the DBusCredentials object only returns the PID FD if it was
obtained by this call, so that we know for sure we can rely on it
being safe against PID reuse attacks.

Signed-off-by: Luca Boccassi <bluca@debian.org>
2023-08-08 12:24:20 +01:00

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/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/* dbus-credentials-util.c Would be in dbus-credentials.c, but only used for tests/bus
*
* Copyright (C) 2007 Red Hat Inc.
*
* SPDX-License-Identifier: AFL-2.1 OR GPL-2.0-or-later
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include <config.h>
#include "misc-internals.h"
#include "dbus/dbus-credentials.h"
#include "dbus/dbus-internals.h"
#include "dbus/dbus-test-tap.h"
#include "dbus/dbus-test.h"
/**
* @addtogroup DBusCredentials
* @{
*/
/** @} */
#ifdef DBUS_ENABLE_EMBEDDED_TESTS
#include <stdio.h>
#include <string.h>
static DBusCredentials*
make_credentials(dbus_uid_t unix_uid,
dbus_pid_t pid,
int group_vector,
const char *windows_sid)
{
DBusCredentials *credentials;
static const struct
{
size_t n;
const dbus_gid_t gids[4];
}
group_vectors[] =
{
{ 4, { 1000, 42, 123, 5678 } },
{ 2, { 23, 1001 } },
{ 4, { 5678, 123, 42, 1000 } }
};
/*
* group_vector is 0 to not add any groups, or n > 0 to add groups from
* group_vectors[n-1].
*/
_dbus_assert (group_vector >= 0);
_dbus_assert (group_vector <= _DBUS_N_ELEMENTS (group_vectors));
credentials = _dbus_credentials_new ();
if (unix_uid != DBUS_UID_UNSET)
{
if (!_dbus_credentials_add_unix_uid (credentials, unix_uid))
{
_dbus_credentials_unref (credentials);
return NULL;
}
}
if (pid != DBUS_PID_UNSET)
{
if (!_dbus_credentials_add_pid (credentials, pid))
{
_dbus_credentials_unref (credentials);
return NULL;
}
}
if (group_vector)
{
dbus_gid_t *copy;
copy = dbus_new0 (dbus_gid_t, group_vectors[group_vector - 1].n);
if (copy == NULL)
{
_dbus_credentials_unref (credentials);
return NULL;
}
memcpy (copy, group_vectors[group_vector - 1].gids,
sizeof (dbus_gid_t) * group_vectors[group_vector - 1].n);
_dbus_credentials_take_unix_gids (credentials, copy,
group_vectors[group_vector - 1].n);
}
if (windows_sid != NULL)
{
if (!_dbus_credentials_add_windows_sid (credentials, windows_sid))
{
_dbus_credentials_unref (credentials);
return NULL;
}
}
return credentials;
}
#define SAMPLE_SID "whatever a windows sid looks like"
#define OTHER_SAMPLE_SID "whatever else"
dbus_bool_t
_dbus_credentials_test (const char *test_data_dir)
{
DBusCredentials *creds;
DBusCredentials *creds2;
DBusString str;
DBusString str2;
const dbus_gid_t *gids;
size_t n;
dbus_pid_t pid = _dbus_getpid();
if (test_data_dir == NULL)
return TRUE;
creds = make_credentials (12, pid, 1, SAMPLE_SID);
if (creds == NULL)
_dbus_test_fatal ("oom");
/* test refcounting */
_dbus_credentials_ref (creds);
_dbus_credentials_unref (creds);
_dbus_assert (_dbus_credentials_include (creds, DBUS_CREDENTIAL_UNIX_USER_ID));
_dbus_assert (_dbus_credentials_include (creds, DBUS_CREDENTIAL_UNIX_PROCESS_ID));
_dbus_assert (_dbus_credentials_include (creds, DBUS_CREDENTIAL_UNIX_GROUP_IDS));
_dbus_assert (_dbus_credentials_include (creds, DBUS_CREDENTIAL_WINDOWS_SID));
_dbus_assert (_dbus_credentials_get_unix_uid (creds) == 12);
_dbus_assert (_dbus_credentials_get_pid (creds) == pid);
_dbus_assert (strcmp (_dbus_credentials_get_windows_sid (creds), SAMPLE_SID) == 0);
_dbus_assert (_dbus_credentials_get_unix_gids (creds, &gids, &n));
_dbus_assert (n == 4);
_dbus_assert (gids[0] == 42);
_dbus_assert (gids[1] == 123);
_dbus_assert (gids[2] == 1000);
_dbus_assert (gids[3] == 5678);
_dbus_assert (!_dbus_credentials_are_empty (creds));
_dbus_assert (!_dbus_credentials_are_anonymous (creds));
/* Test copy */
creds2 = _dbus_credentials_copy (creds);
if (creds2 == NULL)
_dbus_test_fatal ("oom");
_dbus_assert (_dbus_credentials_include (creds2, DBUS_CREDENTIAL_UNIX_USER_ID));
_dbus_assert (_dbus_credentials_include (creds2, DBUS_CREDENTIAL_UNIX_PROCESS_ID));
_dbus_assert (_dbus_credentials_include (creds2, DBUS_CREDENTIAL_UNIX_GROUP_IDS));
_dbus_assert (_dbus_credentials_include (creds2, DBUS_CREDENTIAL_WINDOWS_SID));
_dbus_assert (_dbus_credentials_get_unix_uid (creds2) == 12);
_dbus_assert (_dbus_credentials_get_pid (creds2) == pid);
_dbus_assert (strcmp (_dbus_credentials_get_windows_sid (creds2), SAMPLE_SID) == 0);
_dbus_assert (_dbus_credentials_get_unix_gids (creds2, &gids, &n));
_dbus_assert (n == 4);
_dbus_assert (gids[0] == 42);
_dbus_assert (gids[1] == 123);
_dbus_assert (gids[2] == 1000);
_dbus_assert (gids[3] == 5678);
_dbus_assert (_dbus_credentials_are_superset (creds, creds2));
_dbus_credentials_unref (creds2);
/* Same user if both unix and windows are the same */
creds2 = make_credentials (12, DBUS_PID_UNSET, 0, SAMPLE_SID);
if (creds2 == NULL)
_dbus_test_fatal ("oom");
_dbus_assert (_dbus_credentials_same_user (creds, creds2));
_dbus_credentials_unref (creds2);
/* Not the same user if Windows is missing */
creds2 = make_credentials (12, DBUS_PID_UNSET, 0, NULL);
if (creds2 == NULL)
_dbus_test_fatal ("oom");
_dbus_assert (!_dbus_credentials_same_user (creds, creds2));
_dbus_assert (_dbus_credentials_are_superset (creds, creds2));
_dbus_credentials_unref (creds2);
/* Not the same user if Windows is different */
creds2 = make_credentials (12, DBUS_PID_UNSET, 0, OTHER_SAMPLE_SID);
if (creds2 == NULL)
_dbus_test_fatal ("oom");
_dbus_assert (!_dbus_credentials_same_user (creds, creds2));
_dbus_assert (!_dbus_credentials_are_superset (creds, creds2));
_dbus_credentials_unref (creds2);
/* Not the same user if Unix is missing */
creds2 = make_credentials (DBUS_UID_UNSET, DBUS_PID_UNSET, 0, SAMPLE_SID);
if (creds2 == NULL)
_dbus_test_fatal ("oom");
_dbus_assert (!_dbus_credentials_same_user (creds, creds2));
_dbus_assert (_dbus_credentials_are_superset (creds, creds2));
_dbus_credentials_unref (creds2);
/* Not the same user if Unix is different */
creds2 = make_credentials (15, DBUS_PID_UNSET, 0, SAMPLE_SID);
if (creds2 == NULL)
_dbus_test_fatal ("oom");
_dbus_assert (!_dbus_credentials_same_user (creds, creds2));
_dbus_assert (!_dbus_credentials_are_superset (creds, creds2));
_dbus_credentials_unref (creds2);
/* Not the same user if both are missing */
creds2 = make_credentials (DBUS_UID_UNSET, DBUS_PID_UNSET, 0, NULL);
if (creds2 == NULL)
_dbus_test_fatal ("oom");
_dbus_assert (!_dbus_credentials_same_user (creds, creds2));
_dbus_assert (_dbus_credentials_are_superset (creds, creds2));
_dbus_credentials_unref (creds2);
/* Same user, but not a superset, if groups are different */
creds2 = make_credentials (12, pid, 2, SAMPLE_SID);
if (creds2 == NULL)
_dbus_test_fatal ("oom");
_dbus_assert (_dbus_credentials_same_user (creds, creds2));
_dbus_assert (!_dbus_credentials_are_superset (creds, creds2));
_dbus_credentials_unref (creds2);
/* Groups being in the same order make no difference */
creds2 = make_credentials (12, pid, 3, SAMPLE_SID);
if (creds2 == NULL)
_dbus_test_fatal ("oom");
_dbus_assert (_dbus_credentials_same_user (creds, creds2));
_dbus_assert (_dbus_credentials_are_superset (creds, creds2));
_dbus_assert (_dbus_credentials_are_superset (creds2, creds));
_dbus_credentials_unref (creds2);
/* Clearing credentials works */
_dbus_credentials_clear (creds);
_dbus_assert (!_dbus_credentials_include (creds, DBUS_CREDENTIAL_UNIX_USER_ID));
_dbus_assert (!_dbus_credentials_include (creds, DBUS_CREDENTIAL_UNIX_PROCESS_ID));
_dbus_assert (!_dbus_credentials_include (creds, DBUS_CREDENTIAL_WINDOWS_SID));
_dbus_assert (_dbus_credentials_get_unix_uid (creds) == DBUS_UID_UNSET);
_dbus_assert (_dbus_credentials_get_pid (creds) == DBUS_PID_UNSET);
_dbus_assert (_dbus_credentials_get_windows_sid (creds) == NULL);
_dbus_assert (_dbus_credentials_are_empty (creds));
_dbus_assert (_dbus_credentials_are_anonymous (creds));
_dbus_credentials_unref (creds);
/* Make some more realistic credentials blobs to test stringification */
if (!_dbus_string_init (&str) || !_dbus_string_init (&str2))
_dbus_test_fatal ("oom");
creds = make_credentials (12, DBUS_PID_UNSET, 0, NULL);
if (creds == NULL)
_dbus_test_fatal ("oom");
if (!_dbus_credentials_to_string_append (creds, &str))
_dbus_test_fatal ("oom");
_dbus_test_diag ("Unix uid only: %s", _dbus_string_get_const_data (&str));
_dbus_assert (strcmp (_dbus_string_get_const_data (&str),
"uid=12") == 0);
_dbus_credentials_unref (creds);
creds = make_credentials (12, pid, 1, NULL);
if (creds == NULL)
_dbus_test_fatal ("oom");
if (!_dbus_string_set_length (&str, 0))
_dbus_test_fatal ("oom");
if (!_dbus_credentials_to_string_append (creds, &str))
_dbus_test_fatal ("oom");
if (!_dbus_string_append_printf(&str2, "uid=12 pid=" DBUS_PID_FORMAT " gid=42 gid=123 gid=1000 gid=5678", pid))
_dbus_test_fatal ("oom");
_dbus_test_diag ("Unix complete set: %s", _dbus_string_get_const_data (&str));
_dbus_assert (strcmp (_dbus_string_get_const_data (&str), _dbus_string_get_const_data (&str2)) == 0);
_dbus_credentials_unref (creds);
creds = make_credentials (DBUS_UID_UNSET, DBUS_PID_UNSET, 0, SAMPLE_SID);
if (creds == NULL)
_dbus_test_fatal ("oom");
if (!_dbus_string_set_length (&str, 0))
_dbus_test_fatal ("oom");
if (!_dbus_credentials_to_string_append (creds, &str))
_dbus_test_fatal ("oom");
_dbus_test_diag ("Windows sid only: %s", _dbus_string_get_const_data (&str));
_dbus_assert (strcmp (_dbus_string_get_const_data (&str),
"sid=" SAMPLE_SID) == 0);
_dbus_credentials_unref (creds);
creds = make_credentials (DBUS_UID_UNSET, pid, 0, SAMPLE_SID);
if (creds == NULL)
_dbus_test_fatal ("oom");
if (!_dbus_string_set_length (&str, 0) || !_dbus_string_set_length (&str2, 0))
_dbus_test_fatal ("oom");
if (!_dbus_credentials_to_string_append (creds, &str))
_dbus_test_fatal ("oom");
if (!_dbus_string_append_printf(&str2, "pid=" DBUS_PID_FORMAT " sid=" SAMPLE_SID, pid))
_dbus_test_fatal ("oom");
_dbus_test_diag ("Windows complete set: %s", _dbus_string_get_const_data (&str));
_dbus_assert (strcmp (_dbus_string_get_const_data (&str), _dbus_string_get_const_data (&str2)) == 0);
_dbus_credentials_unref (creds);
_dbus_string_free (&str);
_dbus_string_free (&str2);
return TRUE;
}
#endif /* DBUS_ENABLE_EMBEDDED_TESTS */
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