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xrdp/sesman/libsesman/sesman_config.c
T
Lennart Sauerbeck 5741653900 sesman: Prevent the use of 'alternate shell' 
By setting the new config value 'AllowAlternateShell' to 'no' it is now
possible to prevent the use of an alternate shell, which can be set by
the connecting user.
The default remains unchanged and any shell is allowed if the config
value is not specified. It can also be set explicitly to 'yes' to achieve
the same outcome.

Fixes: #850
2023-04-19 10:16:56 +01:00

738 lines
22 KiB
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/**
* xrdp: A Remote Desktop Protocol server.
*
* Copyright (C) Jay Sorg 2004-2013
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
*
* @file config.c
* @brief User authentication code
* @author Simone Fedele @< simo [at] esseemme [dot] org @>
*
*/
#if defined(HAVE_CONFIG_H)
#include <config_ac.h>
#endif
#include "arch.h"
#include "sesman_config.h"
#include "sesman_clip_restrict.h"
#include "list.h"
#include "file.h"
#include "log.h"
#include "os_calls.h"
#include "string_calls.h"
//#include "chansrv/chansrv_common.h"
#include "scp.h"
#define SESMAN_CFG_GLOBALS "Globals"
#define SESMAN_CFG_DEFWM "DefaultWindowManager"
#define SESMAN_CFG_ADDRESS "ListenAddress"
#define SESMAN_CFG_PORT "ListenPort"
#define SESMAN_CFG_ENABLE_USERWM "EnableUserWindowManager"
#define SESMAN_CFG_USERWM "UserWindowManager"
#define SESMAN_CFG_AUTH_FILE_PATH "AuthFilePath"
#define SESMAN_CFG_RECONNECT_SH "ReconnectScript"
#define SESMAN_CFG_XORG_PARAMS "Xorg"
#define SESMAN_CFG_VNC_PARAMS "Xvnc"
#define SESMAN_CFG_SESSION_VARIABLES "SessionVariables"
/*
#define SESMAN_CFG_LOGGING "Logging"
#define SESMAN_CFG_LOG_FILE "LogFile"
#define SESMAN_CFG_LOG_LEVEL "LogLevel"
#define SESMAN_CFG_LOG_ENABLE_SYSLOG "EnableSyslog"
#define SESMAN_CFG_LOG_SYSLOG_LEVEL "SyslogLevel"
*/
#define SESMAN_CFG_SECURITY "Security"
#define SESMAN_CFG_SEC_LOGIN_RETRY "MaxLoginRetry"
#define SESMAN_CFG_SEC_ALLOW_ROOT "AllowRootLogin"
#define SESMAN_CFG_SEC_USR_GROUP "TerminalServerUsers"
#define SESMAN_CFG_SEC_ADM_GROUP "TerminalServerAdmins"
#define SESMAN_CFG_SEC_ALWAYSGROUPCHECK "AlwaysGroupCheck"
#define SESMAN_CFG_SEC_RESTRICT_OUTBOUND_CLIPBOARD "RestrictOutboundClipboard"
#define SESMAN_CFG_SEC_RESTRICT_INBOUND_CLIPBOARD "RestrictInboundClipboard"
#define SESMAN_CFG_SEC_ALLOW_ALTERNATE_SHELL "AllowAlternateShell"
#define SESMAN_CFG_SESSIONS "Sessions"
#define SESMAN_CFG_SESS_MAX "MaxSessions"
#define SESMAN_CFG_SESS_KILL_DISC "KillDisconnected"
#define SESMAN_CFG_SESS_IDLE_LIMIT "IdleTimeLimit"
#define SESMAN_CFG_SESS_DISC_LIMIT "DisconnectedTimeLimit"
#define SESMAN_CFG_SESS_X11DISPLAYOFFSET "X11DisplayOffset"
#define SESMAN_CFG_SESS_POLICY_S "Policy"
#define SESMAN_CFG_SESS_POLICY_DFLT_S "Default"
#define SESMAN_CFG_SESS_POLICY_SEP_S "Separate"
static const struct bitmask_char policy_bits[] =
{
{ SESMAN_CFG_SESS_POLICY_U, 'U' },
{ SESMAN_CFG_SESS_POLICY_B, 'B' },
{ SESMAN_CFG_SESS_POLICY_D, 'D' },
{ SESMAN_CFG_SESS_POLICY_I, 'I' },
BITMASK_CHAR_END_OF_LIST
};
/***************************************************************************//**
* Parse a session allocation policy string
*/
static unsigned int
parse_policy_string(const char *value)
{
unsigned int rv;
char unrecognised[16];
if (0 == g_strcasecmp(value, SESMAN_CFG_SESS_POLICY_DFLT_S))
{
rv = SESMAN_CFG_SESS_POLICY_DEFAULT;
}
else if (0 == g_strcasecmp(value, SESMAN_CFG_SESS_POLICY_SEP_S))
{
rv = SESMAN_CFG_SESS_POLICY_SEPARATE;
}
else
{
unrecognised[0] = '\0';
rv = g_charstr_to_bitmask(value, policy_bits, unrecognised,
sizeof(unrecognised));
if (unrecognised[0] != '\0')
{
LOG(LOG_LEVEL_WARNING, "Character(s) '%s' in the session"
" allocation policy are not recognised", unrecognised);
if (g_strchr(unrecognised, 'C') != NULL ||
g_strchr(unrecognised, 'c') != NULL)
{
/* Change from xrdp v0.9.x */
LOG(LOG_LEVEL_WARNING, "Character 'C' is no longer used"
" in session allocation policies - use '%s'",
SESMAN_CFG_SESS_POLICY_SEP_S);
}
}
}
return rv;
}
/******************************************************************************/
int
config_output_policy_string(unsigned int value,
char *buff, unsigned int bufflen)
{
int rv = 0;
if (bufflen > 0)
{
if (value & SESMAN_CFG_SESS_POLICY_DEFAULT)
{
rv = g_snprintf(buff, bufflen, "Default");
}
else if (value & SESMAN_CFG_SESS_POLICY_SEPARATE)
{
rv = g_snprintf(buff, bufflen, "Separate");
}
else
{
rv = g_bitmask_to_charstr(value, policy_bits, buff, bufflen, NULL);
}
}
return rv;
}
/***************************************************************************//**
*
* @brief Reads sesman [global] configuration section
* @param file configuration file descriptor
* @param cf pointer to a config struct
* @param param_n parameter name list
* @param param_v parameter value list
* @return 0 on success, 1 on failure
*
*/
static int
config_read_globals(int file, struct config_sesman *cf, struct list *param_n,
struct list *param_v)
{
int i;
list_clear(param_v);
list_clear(param_n);
/* resetting the struct */
cf->listen_port[0] = '\0';
cf->enable_user_wm = 0;
cf->user_wm[0] = '\0';
cf->default_wm = 0;
cf->auth_file_path = 0;
cf->reconnect_sh = 0;
file_read_section(file, SESMAN_CFG_GLOBALS, param_n, param_v);
for (i = 0; i < param_n->count; i++)
{
const char *param = (const char *)list_get_item(param_n, i);
const char *val = (const char *)list_get_item(param_v, i);
if (0 == g_strcasecmp(param, SESMAN_CFG_DEFWM))
{
cf->default_wm = g_strdup(val);
}
else if (0 == g_strcasecmp(param, SESMAN_CFG_USERWM))
{
g_strncpy(cf->user_wm, val, sizeof(cf->user_wm) - 1);
}
else if (0 == g_strcasecmp(param, SESMAN_CFG_ENABLE_USERWM))
{
cf->enable_user_wm = g_text2bool(val);
}
else if (0 == g_strcasecmp(param, SESMAN_CFG_PORT))
{
scp_port_to_unix_domain_path(val, cf->listen_port,
sizeof(cf->listen_port));
}
else if (0 == g_strcasecmp(param, SESMAN_CFG_AUTH_FILE_PATH))
{
cf->auth_file_path = g_strdup(val);
}
else if (g_strcasecmp(param, SESMAN_CFG_RECONNECT_SH) == 0)
{
cf->reconnect_sh = g_strdup(val);
}
else if (0 == g_strcasecmp(param, SESMAN_CFG_ADDRESS))
{
/* Config must be updated for Unix Domain Sockets */
LOG(LOG_LEVEL_WARNING, "Obsolete setting' " SESMAN_CFG_ADDRESS
"' in [" SESMAN_CFG_GLOBALS "] should be removed.");
LOG(LOG_LEVEL_WARNING, "Review setting' " SESMAN_CFG_PORT "' in ["
SESMAN_CFG_GLOBALS "]");
}
}
/* checking for missing required parameters */
if ('\0' == cf->listen_port[0])
{
/* Load the default value */
scp_port_to_unix_domain_path(NULL, cf->listen_port,
sizeof(cf->listen_port));
}
if ('\0' == cf->user_wm[0])
{
cf->enable_user_wm = 0;
}
if (cf->default_wm == 0 || cf->default_wm[0] == '\0')
{
g_free(cf->default_wm);
cf->default_wm = g_strdup("startwm.sh");
}
/* if default_wm doesn't begin with '/', it's a relative path to
* XRDP_CFG_PATH */
if (cf->default_wm[0] != '/')
{
/* sizeof operator returns string length including null terminator */
int length = (sizeof(XRDP_CFG_PATH) +
g_strlen(cf->default_wm) + 1); /* '/' */
char *buf = (char *)g_malloc(length, 0);
g_sprintf(buf, "%s/%s", XRDP_CFG_PATH, cf->default_wm);
g_free(cf->default_wm);
cf->default_wm = buf;
}
if (cf->reconnect_sh == 0 || cf->reconnect_sh[0] == '\0')
{
g_free(cf->reconnect_sh);
cf->reconnect_sh = g_strdup("reconnectwm.sh");
}
/* if reconnect_sh doesn't begin with '/', it's a relative path to
* XRDP_CFG_PATH */
if (cf->reconnect_sh[0] != '/')
{
/* sizeof operator returns string length including null terminator */
int length = (sizeof(XRDP_CFG_PATH) +
g_strlen(cf->reconnect_sh) + 1); /* '/' */
char *buf = (char *)g_malloc(length, 0);
g_sprintf(buf, "%s/%s", XRDP_CFG_PATH, cf->reconnect_sh);
g_free(cf->reconnect_sh);
cf->reconnect_sh = buf;
}
return 0;
}
/***************************************************************************//**
*
* @brief Reads sesman [Security] configuration section
* @param file configuration file descriptor
* @param sc pointer to a config_security struct
* @param param_n parameter name list
* @param param_v parameter value list
* @return 0 on success, 1 on failure
*
*/
static int
config_read_security(int file, struct config_security *sc,
struct list *param_n,
struct list *param_v)
{
int i;
int gid;
char *buf;
list_clear(param_v);
list_clear(param_n);
/* setting defaults */
sc->allow_root = 0;
sc->login_retry = 3;
sc->ts_users_enable = 0;
sc->ts_admins_enable = 0;
sc->restrict_outbound_clipboard = 0;
sc->restrict_inbound_clipboard = 0;
sc->allow_alternate_shell = 1;
file_read_section(file, SESMAN_CFG_SECURITY, param_n, param_v);
for (i = 0; i < param_n->count; i++)
{
buf = (char *)list_get_item(param_n, i);
if (0 == g_strcasecmp(buf, SESMAN_CFG_SEC_ALLOW_ROOT))
{
sc->allow_root = g_text2bool((char *)list_get_item(param_v, i));
}
if (0 == g_strcasecmp(buf, SESMAN_CFG_SEC_LOGIN_RETRY))
{
sc->login_retry = g_atoi((char *)list_get_item(param_v, i));
}
if (0 == g_strcasecmp(buf, SESMAN_CFG_SEC_USR_GROUP))
{
if (g_getgroup_info((char *)list_get_item(param_v, i), &gid) == 0)
{
sc->ts_users_enable = 1;
sc->ts_users = gid;
}
}
if (0 == g_strcasecmp(buf, SESMAN_CFG_SEC_ADM_GROUP))
{
if (g_getgroup_info((char *)list_get_item(param_v, i), &gid) == 0)
{
sc->ts_admins_enable = 1;
sc->ts_admins = gid;
}
}
if (0 == g_strcasecmp(buf, SESMAN_CFG_SEC_ALWAYSGROUPCHECK))
{
sc->ts_always_group_check = g_text2bool((char *)list_get_item(param_v, i));
}
if (0 == g_strcasecmp(buf, SESMAN_CFG_SEC_RESTRICT_OUTBOUND_CLIPBOARD))
{
char unrecognised[256];
sc->restrict_outbound_clipboard =
sesman_clip_restrict_string_to_bitmask(
(const char *)list_get_item(param_v, i),
unrecognised, sizeof(unrecognised));
if (unrecognised[0] != '\0')
{
LOG(LOG_LEVEL_WARNING,
"Unrecognised tokens parsing 'RestrictOutboundClipboard' %s",
unrecognised);
}
}
if (0 == g_strcasecmp(buf, SESMAN_CFG_SEC_RESTRICT_INBOUND_CLIPBOARD))
{
char unrecognised[256];
sc->restrict_inbound_clipboard =
sesman_clip_restrict_string_to_bitmask(
(const char *)list_get_item(param_v, i),
unrecognised, sizeof(unrecognised));
if (unrecognised[0] != '\0')
{
LOG(LOG_LEVEL_WARNING,
"Unrecognised tokens parsing 'RestrictInboundClipboard' %s",
unrecognised);
}
}
if (0 == g_strcasecmp(buf, SESMAN_CFG_SEC_ALLOW_ALTERNATE_SHELL))
{
sc->allow_alternate_shell =
g_text2bool((char *)list_get_item(param_v, i));
}
}
return 0;
}
/***************************************************************************//**
*
* @brief Reads sesman [Sessions] configuration section
* @param file configuration file descriptor
* @param ss pointer to a config_sessions struct
* @param param_n parameter name list
* @param param_v parameter value list
* @return 0 on success, 1 on failure
*
*/
static int
config_read_sessions(int file, struct config_sessions *se, struct list *param_n,
struct list *param_v)
{
int i;
const char *buf;
const char *value;
list_clear(param_v);
list_clear(param_n);
/* setting defaults */
se->x11_display_offset = 10;
se->max_sessions = 0;
se->max_idle_time = 0;
se->max_disc_time = 0;
se->kill_disconnected = 0;
se->policy = SESMAN_CFG_SESS_POLICY_DEFAULT;
file_read_section(file, SESMAN_CFG_SESSIONS, param_n, param_v);
for (i = 0; i < param_n->count; i++)
{
buf = (const char *)list_get_item(param_n, i);
value = (const char *)list_get_item(param_v, i);
if (0 == g_strcasecmp(buf, SESMAN_CFG_SESS_X11DISPLAYOFFSET))
{
se->x11_display_offset = g_atoi(value);
}
else if (0 == g_strcasecmp(buf, SESMAN_CFG_SESS_MAX))
{
se->max_sessions = g_atoi(value);
}
else if (0 == g_strcasecmp(buf, SESMAN_CFG_SESS_KILL_DISC))
{
se->kill_disconnected = g_text2bool(value);
}
else if (0 == g_strcasecmp(buf, SESMAN_CFG_SESS_IDLE_LIMIT))
{
se->max_idle_time = g_atoi(value);
}
else if (0 == g_strcasecmp(buf, SESMAN_CFG_SESS_DISC_LIMIT))
{
se->max_disc_time = g_atoi(value);
}
else if (0 == g_strcasecmp(buf, SESMAN_CFG_SESS_POLICY_S))
{
se->policy = parse_policy_string(value);
}
}
return 0;
}
/***************************************************************************//**
*
* @brief Reads sesman [Xorg] configuration section
* @param file configuration file descriptor
* @param cs pointer to a config_sesman struct
* @param param_n parameter name list
* @param param_v parameter value list
* @return 0 on success, 1 on failure
*
*/
static int
config_read_xorg_params(int file, struct config_sesman *cs,
struct list *param_n, struct list *param_v)
{
int i;
list_clear(param_v);
list_clear(param_n);
cs->xorg_params = list_create();
cs->xorg_params->auto_free = 1;
file_read_section(file, SESMAN_CFG_XORG_PARAMS, param_n, param_v);
for (i = 0; i < param_n->count; i++)
{
list_add_strdup(cs->xorg_params,
(const char *) list_get_item(param_v, i));
}
return 0;
}
/***************************************************************************//**
*
* @brief Reads sesman [Xvnc] configuration section
* @param file configuration file descriptor
* @param cs pointer to a config_sesman struct
* @param param_n parameter name list
* @param param_v parameter value list
* @return 0 on success, 1 on failure
*
*/
static int
config_read_vnc_params(int file, struct config_sesman *cs, struct list *param_n,
struct list *param_v)
{
int i;
list_clear(param_v);
list_clear(param_n);
cs->vnc_params = list_create();
cs->vnc_params->auto_free = 1;
file_read_section(file, SESMAN_CFG_VNC_PARAMS, param_n, param_v);
for (i = 0; i < param_n->count; i++)
{
list_add_strdup(cs->vnc_params,
(const char *)list_get_item(param_v, i));
}
return 0;
}
/******************************************************************************/
static int
config_read_session_variables(int file, struct config_sesman *cs,
struct list *param_n, struct list *param_v)
{
int i;
list_clear(param_v);
list_clear(param_n);
cs->env_names = list_create();
cs->env_names->auto_free = 1;
cs->env_values = list_create();
cs->env_values->auto_free = 1;
file_read_section(file, SESMAN_CFG_SESSION_VARIABLES, param_n, param_v);
for (i = 0; i < param_n->count; i++)
{
list_add_strdup(cs->env_names,
(const char *) list_get_item(param_n, i));
list_add_strdup(cs->env_values,
(const char *) list_get_item(param_v, i));
}
return 0;
}
/******************************************************************************/
struct config_sesman *
config_read(const char *sesman_ini)
{
struct config_sesman *cfg;
int all_ok = 0;
if ((cfg = g_new0(struct config_sesman, 1)) != NULL)
{
if ((cfg->sesman_ini = g_strdup(sesman_ini)) != NULL)
{
int fd;
if ((fd = g_file_open_ex(cfg->sesman_ini, 1, 0, 0, 0)) != -1)
{
struct list *sec;
struct list *param_n;
struct list *param_v;
sec = list_create();
sec->auto_free = 1;
file_read_sections(fd, sec);
param_n = list_create();
param_n->auto_free = 1;
param_v = list_create();
param_v->auto_free = 1;
all_ok = 1;
/* read global config */
config_read_globals(fd, cfg, param_n, param_v);
/* read Xvnc/Xorg parameter list */
config_read_vnc_params(fd, cfg, param_n, param_v);
config_read_xorg_params(fd, cfg, param_n, param_v);
/* read security config */
config_read_security(fd, &(cfg->sec), param_n, param_v);
/* read session config */
config_read_sessions(fd, &(cfg->sess), param_n, param_v);
config_read_session_variables(fd, cfg, param_n, param_v);
/* cleanup */
list_delete(sec);
list_delete(param_v);
list_delete(param_n);
g_file_close(fd);
}
}
}
if (!all_ok)
{
config_free(cfg);
cfg = NULL;
}
return cfg;
}
/******************************************************************************/
void
config_dump(struct config_sesman *config)
{
int i;
struct config_sessions *se;
struct config_security *sc;
se = &(config->sess);
sc = &(config->sec);
char policy_s[64];
char restrict_s[64];
/* Global sesman configuration */
g_writeln("Filename: %s", config->sesman_ini);
g_writeln("Global configuration:");
g_writeln(" ListenPort: %s", config->listen_port);
g_writeln(" EnableUserWindowManager: %d", config->enable_user_wm);
g_writeln(" UserWindowManager: %s", config->user_wm);
g_writeln(" DefaultWindowManager: %s", config->default_wm);
g_writeln(" ReconnectScript: %s", config->reconnect_sh);
g_writeln(" AuthFilePath: %s",
(config->auth_file_path ? config->auth_file_path : "disabled"));
/* Session configuration */
config_output_policy_string(se->policy, policy_s, sizeof(policy_s));
g_writeln("Session configuration:");
g_writeln(" MaxSessions: %d", se->max_sessions);
g_writeln(" X11DisplayOffset: %d", se->x11_display_offset);
g_writeln(" KillDisconnected: %d", se->kill_disconnected);
g_writeln(" IdleTimeLimit: %d", se->max_idle_time);
g_writeln(" DisconnectedTimeLimit: %d", se->max_disc_time);
g_writeln(" Policy: %s", policy_s);
/* Security configuration */
g_writeln("Security configuration:");
g_writeln(" AllowRootLogin: %d", sc->allow_root);
g_writeln(" MaxLoginRetry: %d", sc->login_retry);
g_writeln(" AlwaysGroupCheck: %d", sc->ts_always_group_check);
g_writeln(" AllowAlternateShell: %d", sc->allow_alternate_shell);
sesman_clip_restrict_mask_to_string(sc->restrict_outbound_clipboard,
restrict_s, sizeof(restrict_s));
g_writeln(" RestrictOutboundClipboard: %s", restrict_s);
sesman_clip_restrict_mask_to_string(sc->restrict_inbound_clipboard,
restrict_s, sizeof(restrict_s));
g_writeln(" RestrictInboundClipboard: %s", restrict_s);
g_printf( " TSUsersGroup: ");
if (sc->ts_users_enable)
{
g_printf("%d", sc->ts_users);
}
else
{
g_printf("(not defined)");
}
g_writeln("%s", "");
g_printf( " TSAdminsGroup: ");
if (sc->ts_admins_enable)
{
g_printf("%d", sc->ts_admins);
}
else
{
g_printf("(not defined)");
}
g_writeln("%s", "");
/* Xorg */
if (config->xorg_params->count)
{
g_writeln("Xorg parameters:");
}
for (i = 0; i < config->xorg_params->count; i++)
{
g_writeln(" Parameter %02d %s",
i, (char *) list_get_item(config->xorg_params, i));
}
/* Xvnc */
if (config->vnc_params->count)
{
g_writeln("Xvnc parameters:");
}
for (i = 0; i < config->vnc_params->count; i++)
{
g_writeln(" Parameter %02d %s",
i, (char *)list_get_item(config->vnc_params, i));
}
/* SessionVariables */
if (config->env_names->count)
{
g_writeln("%s parameters:", SESMAN_CFG_SESSION_VARIABLES);
}
for (i = 0; i < config->env_names->count; i++)
{
g_writeln(" Parameter %02d %s=%s",
i, (char *) list_get_item(config->env_names, i),
(char *) list_get_item(config->env_values, i));
}
}
/******************************************************************************/
void
config_free(struct config_sesman *cs)
{
if (cs != NULL)
{
g_free(cs->sesman_ini);
g_free(cs->default_wm);
g_free(cs->reconnect_sh);
g_free(cs->auth_file_path);
list_delete(cs->vnc_params);
list_delete(cs->xorg_params);
list_delete(cs->env_names);
list_delete(cs->env_values);
g_free(cs);
}
}
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