/* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
#include <priv.h>
#include <sys/types.h>
#include <unistd.h>
#include "httpd.h"
#include "http_config.h"
#include "http_protocol.h"
#include "http_log.h"
#include "mpm_common.h"
#include "ap_mpm.h"
#include "apr_strings.h"
/* TODO - get rid of unixd dependency */
#include "unixd.h"
#define CFG_CHECK(x) if ((x) == -1) { \
char msgbuf[128]; \
apr_strerror(errno, msgbuf, sizeof(msgbuf)); \
return apr_pstrdup(cmd->pool, msgbuf); \
}
#define CR_CHECK(x, y) if (x == -1) \
ap_log_error(APLOG_MARK, APLOG_CRIT, errno, 0, y \
"Failed to initialise privileges")
module AP_MODULE_DECLARE_DATA privileges_module;
/* #define BIG_SECURITY_HOLE 1 */
typedef enum { PRIV_UNSET, PRIV_FAST, PRIV_SECURE, PRIV_SELECTIVE } priv_mode;
typedef struct {
priv_set_t *priv;
priv_set_t *child_priv;
uid_t uid;
gid_t gid;
priv_mode mode;
} priv_cfg;
typedef struct {
priv_mode mode;
} priv_dir_cfg;
static priv_set_t *priv_setid;
static priv_set_t *priv_default = NULL;
static int dtrace_enabled = 0;
static apr_status_t priv_cfg_cleanup(void *CFG)
{
priv_cfg *cfg = CFG;
priv_freeset(cfg->priv);
priv_freeset(cfg->child_priv);
return APR_SUCCESS;
}
static void *privileges_merge_cfg(apr_pool_t *pool, void *BASE, void *ADD)
{
/* inherit the mode if it's not set; the rest won't be inherited */
priv_cfg *base = BASE;
priv_cfg *add = ADD;
priv_cfg *ret = apr_pmemdup(pool, add, sizeof(priv_cfg));
ret->mode = (add->mode == PRIV_UNSET) ? base->mode : add->mode;
return ret;
}
static void *privileges_create_cfg(apr_pool_t *pool, server_rec *s)
{
priv_cfg *cfg = apr_palloc(pool, sizeof(priv_cfg));
/* Start at basic privileges all round. */
cfg->priv = priv_str_to_set("basic", ",", NULL);
cfg->child_priv = priv_str_to_set("basic", ",", NULL);
/* By default, run in secure vhost mode.
* That means dropping basic privileges we don't usually need.
*/
CR_CHECK(priv_delset(cfg->priv, PRIV_FILE_LINK_ANY), APLOGNO(03160));
CR_CHECK(priv_delset(cfg->priv, PRIV_PROC_INFO), APLOGNO(03161));
CR_CHECK(priv_delset(cfg->priv, PRIV_PROC_SESSION), APLOGNO(03162));
/* Hmmm, should CGI default to secure too ? */
/*
CR_CHECK(priv_delset(cfg->child_priv, PRIV_FILE_LINK_ANY), APLOGNO(03163));
CR_CHECK(priv_delset(cfg->child_priv, PRIV_PROC_INFO), APLOGNO(03164));
CR_CHECK(priv_delset(cfg->child_priv, PRIV_PROC_SESSION), APLOGNO(03165));
CR_CHECK(priv_delset(cfg->child_priv, PRIV_PROC_FORK), APLOGNO(03166));
CR_CHECK(priv_delset(cfg->child_priv, PRIV_PROC_EXEC), APLOGNO(03167));
*/
/* we´ll use 0 for unset */
cfg->uid = 0;
cfg->gid = 0;
cfg->mode = PRIV_UNSET;
apr_pool_cleanup_register(pool, cfg, priv_cfg_cleanup,
apr_pool_cleanup_null);
/* top-level default_priv wants the top-level cfg */
if (priv_default == NULL) {
priv_default = cfg->priv;
}
return cfg;
}
static void *privileges_create_dir_cfg(apr_pool_t *pool, char *dummy)
{
priv_dir_cfg *cfg = apr_palloc(pool, sizeof(priv_dir_cfg));
cfg->mode = PRIV_UNSET;
return cfg;
}
static void *privileges_merge_dir_cfg(apr_pool_t *pool, void *BASE, void *ADD)
{
priv_dir_cfg *base = BASE;
priv_dir_cfg *add = ADD;
priv_dir_cfg *ret = apr_palloc(pool, sizeof(priv_dir_cfg));
ret->mode = (add->mode == PRIV_UNSET) ? base->mode : add->mode;
return ret;
}
static apr_status_t privileges_end_req(void *data)
{
request_rec *r = data;
priv_cfg *cfg = ap_get_module_config(r->server->module_config,
&privileges_module);
priv_dir_cfg *dcfg = ap_get_module_config(r->per_dir_config,
&privileges_module);
/* ugly hack: grab default uid and gid from unixd */
extern unixd_config_rec ap_unixd_config;
/* If we forked a child, we dropped privilege to revert, so
* all we can do now is exit
*/
if ((cfg->mode == PRIV_SECURE) ||
((cfg->mode == PRIV_SELECTIVE) && (dcfg->mode == PRIV_SECURE))) {
exit(0);
}
/* if either user or group are not the default, restore them */
if (cfg->uid || cfg->gid) {
if (setppriv(PRIV_ON, PRIV_EFFECTIVE, priv_setid) == -1) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02136)
"PRIV_ON failed restoring default user/group");
}
if (cfg->uid && (setuid(ap_unixd_config.user_id) == -1)) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02137)
"Error restoring default userid");
}
if (cfg->gid && (setgid(ap_unixd_config.group_id) == -1)) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02138)
"Error restoring default group");
}
}
/* restore default privileges */
if (setppriv(PRIV_SET, PRIV_EFFECTIVE, priv_default) == -1) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, errno, r, APLOGNO(02139)
"Error restoring default privileges");
}
return APR_SUCCESS;
}
static int privileges_req(request_rec *r)
{
/* secure mode: fork a process to handle the request */
apr_proc_t proc;
apr_status_t rv;
int exitcode;
apr_exit_why_e exitwhy;
int fork_req;
priv_cfg *cfg = ap_get_module_config(r->server->module_config,
&privileges_module);
void *breadcrumb = ap_get_module_config(r->request_config,
&privileges_module);
if (!breadcrumb) {
/* first call: this is the vhost */
fork_req = (cfg->mode == PRIV_SECURE);
/* set breadcrumb */
ap_set_module_config(r->request_config, &privileges_module, &cfg->mode);
/* If we have per-dir config, defer doing anything */
if ((cfg->mode == PRIV_SELECTIVE)) {
/* Defer dropping privileges 'til we have a directory
* context that'll tell us whether to fork.
*/
return DECLINED;
}
}
else {
/* second call is for per-directory. */
priv_dir_cfg *dcfg;
if ((cfg->mode != PRIV_SELECTIVE)) {
/* Our fate was already determined for the vhost -
* nothing to do per-directory
*/
return DECLINED;
}
dcfg = ap_get_module_config(r->per_dir_config, &privileges_module);
fork_req = (dcfg->mode == PRIV_SECURE);
}
if (fork_req) {
rv = apr_proc_fork(&proc, r->pool);
switch (rv) {
case APR_INPARENT:
ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02140)
"parent waiting for child");
/* FIXME - does the child need to run synchronously?
* esp. if we enable mod_privileges with threaded MPMs?
* We do need at least to ensure r outlives the child.
*/
rv = apr_proc_wait(&proc, &exitcode, &exitwhy, APR_WAIT);
ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02141) "parent: child %s",
(rv == APR_CHILD_DONE) ? "done" : "notdone");
/* The child has taken responsibility for reading all input
* and sending all output. So we need to bow right out,
* and even abandon "normal" housekeeping.
*/
r->eos_sent = 1;
apr_table_unset(r->headers_in, "Content-Type");
apr_table_unset(r->headers_in, "Content-Length");
/* Testing with ab and 100k requests reveals no nasties
* so I infer we're not leaking anything like memory
* or file descriptors. That's nice!
*/
return DONE;
case APR_INCHILD:
ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02142) "In child!");
break; /* now we'll drop privileges in the child */
default:
ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02143)
"Failed to fork secure child process!");
return HTTP_INTERNAL_SERVER_ERROR;
}
}
/* OK, now drop privileges. */
/* cleanup should happen even if something fails part-way through here */
apr_pool_cleanup_register(r->pool, r, privileges_end_req,
apr_pool_cleanup_null);
/* set user and group if configured */
if (cfg->uid || cfg->gid) {
if (setppriv(PRIV_ON, PRIV_EFFECTIVE, priv_setid) == -1) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02144)
"No privilege to set user/group");
}
/* if we should be able to set these but can't, it could be
* a serious security issue. Bail out rather than risk it!
*/
if (cfg->uid && (setuid(cfg->uid) == -1)) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02145)
"Error setting userid");
return HTTP_INTERNAL_SERVER_ERROR;
}
if (cfg->gid && (setgid(cfg->gid) == -1)) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02146)
"Error setting group");
return HTTP_INTERNAL_SERVER_ERROR;
}
}
/* set vhost's privileges */
if (setppriv(PRIV_SET, PRIV_EFFECTIVE, cfg->priv) == -1) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, errno, r, APLOGNO(02147)
"Error setting effective privileges");
return HTTP_INTERNAL_SERVER_ERROR;
}
/* ... including those of any subprocesses */
if (setppriv(PRIV_SET, PRIV_INHERITABLE, cfg->child_priv) == -1) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, errno, r, APLOGNO(02148)
"Error setting inheritable privileges");
return HTTP_INTERNAL_SERVER_ERROR;
}
if (setppriv(PRIV_SET, PRIV_LIMIT, cfg->child_priv) == -1) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, errno, r, APLOGNO(02149)
"Error setting limit privileges");
return HTTP_INTERNAL_SERVER_ERROR;
}
/* If we're in a child process, drop down PPERM too */
if (fork_req) {
if (setppriv(PRIV_SET, PRIV_PERMITTED, cfg->priv) == -1) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, errno, r, APLOGNO(02150)
"Error setting permitted privileges");
return HTTP_INTERNAL_SERVER_ERROR;
}
}
return OK;
}
#define PDROP_CHECK(x) if (x == -1) { \
ap_log_error(APLOG_MARK, APLOG_CRIT, errno, s, APLOGNO(02151) \
"Error dropping privileges"); \
return !OK; \
}
static int privileges_drop_first(apr_pool_t *pool, server_rec *s)
{
/* We need to set privileges before mod_unixd,
* 'cos otherwise setuid will wipe our privilege to do so
*/
priv_cfg *spcfg;
server_rec *sp;
priv_set_t *ppriv = priv_allocset();
/* compute ppriv from the union of all the vhosts plus setid */
priv_copyset(priv_setid, ppriv);
for (sp = s; sp != NULL; sp=sp->next) {
spcfg = ap_get_module_config(sp->module_config, &privileges_module);
priv_union(spcfg->priv, ppriv);
}
PDROP_CHECK(setppriv(PRIV_SET, PRIV_PERMITTED, ppriv))
PDROP_CHECK(setppriv(PRIV_SET, PRIV_EFFECTIVE, ppriv))
priv_freeset(ppriv);
return OK;
}
static int privileges_drop_last(apr_pool_t *pool, server_rec *s)
{
/* Our config stuff has set the privileges we need, so now
* we just set them to those of the parent server_rec
*
* This has to happen after mod_unixd, 'cos mod_unixd needs
* privileges we drop here.
*/
priv_cfg *cfg = ap_get_module_config(s->module_config, &privileges_module);
/* defaults - the default vhost */
PDROP_CHECK(setppriv(PRIV_SET, PRIV_LIMIT, cfg->child_priv))
PDROP_CHECK(setppriv(PRIV_SET, PRIV_INHERITABLE, cfg->child_priv))
PDROP_CHECK(setppriv(PRIV_SET, PRIV_EFFECTIVE, cfg->priv))
return OK;
}
static apr_status_t privileges_term(void *rec)
{
priv_freeset(priv_setid);
return APR_SUCCESS;
}
static int privileges_postconf(apr_pool_t *pconf, apr_pool_t *plog,
apr_pool_t *ptemp, server_rec *s)
{
priv_cfg *cfg;
server_rec *sp;
/* if we have dtrace enabled, merge it into everything */
if (dtrace_enabled) {
for (sp = s; sp != NULL; sp = sp->next) {
cfg = ap_get_module_config(sp->module_config, &privileges_module);
CR_CHECK(priv_addset(cfg->priv, PRIV_DTRACE_KERNEL), APLOGNO(03168));
CR_CHECK(priv_addset(cfg->priv, PRIV_DTRACE_PROC), APLOGNO(03169));
CR_CHECK(priv_addset(cfg->priv, PRIV_DTRACE_USER), APLOGNO(03170));
CR_CHECK(priv_addset(cfg->child_priv, PRIV_DTRACE_KERNEL), APLOGNO(03171));
CR_CHECK(priv_addset(cfg->child_priv, PRIV_DTRACE_PROC), APLOGNO(03172));
CR_CHECK(priv_addset(cfg->child_priv, PRIV_DTRACE_USER), APLOGNO(03173));
}
CR_CHECK(priv_addset(priv_default, PRIV_DTRACE_KERNEL), APLOGNO(03174));
CR_CHECK(priv_addset(priv_default, PRIV_DTRACE_PROC), APLOGNO(03175));
CR_CHECK(priv_addset(priv_default, PRIV_DTRACE_USER), APLOGNO(03176));
}
/* set up priv_setid for per-request use */
priv_setid = priv_allocset();
apr_pool_cleanup_register(pconf, NULL, privileges_term,
apr_pool_cleanup_null);
priv_emptyset(priv_setid);
if (priv_addset(priv_setid, PRIV_PROC_SETID) == -1) {
ap_log_perror(APLOG_MARK, APLOG_CRIT, errno, ptemp, APLOGNO(02152)
"priv_addset");
return !OK;
}
return OK;
}
static int privileges_init(apr_pool_t *pconf, apr_pool_t *plog,
apr_pool_t *ptemp)
{
/* refuse to work if the MPM is threaded */
int threaded;
int rv = ap_mpm_query(AP_MPMQ_IS_THREADED, &threaded);
if (rv != APR_SUCCESS) {
ap_log_perror(APLOG_MARK, APLOG_NOTICE, rv, ptemp, APLOGNO(02153)
"mod_privileges: unable to determine MPM characteristics."
" Please ensure you are using a non-threaded MPM "
"with this module.");
}
if (threaded) {
ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, ptemp, APLOGNO(02154)
"mod_privileges is not compatible with a threaded MPM.");
return !OK;
}
return OK;
}
static void privileges_hooks(apr_pool_t *pool)
{
ap_hook_post_read_request(privileges_req, NULL, NULL,
APR_HOOK_REALLY_FIRST);
ap_hook_header_parser(privileges_req, NULL, NULL, APR_HOOK_REALLY_FIRST);
ap_hook_drop_privileges(privileges_drop_first, NULL, NULL, APR_HOOK_FIRST);
ap_hook_drop_privileges(privileges_drop_last, NULL, NULL, APR_HOOK_LAST);
ap_hook_post_config(privileges_postconf, NULL, NULL, APR_HOOK_MIDDLE);
ap_hook_pre_config(privileges_init, NULL, NULL, APR_HOOK_FIRST);
}
static const char *vhost_user(cmd_parms *cmd, void *dir, const char *arg)
{
priv_cfg *cfg = ap_get_module_config(cmd->server->module_config,
&privileges_module);
cfg->uid = ap_uname2id(arg);
if (cfg->uid == 0) {
return apr_pstrcat(cmd->pool, "Invalid userid for VHostUser: ",
arg, NULL);
}
return NULL;
}
static const char *vhost_group(cmd_parms *cmd, void *dir, const char *arg)
{
priv_cfg *cfg = ap_get_module_config(cmd->server->module_config,
&privileges_module);
cfg->gid = ap_gname2id(arg);
if (cfg->uid == 0) {
return apr_pstrcat(cmd->pool, "Invalid groupid for VHostGroup: ",
arg, NULL);
}
return NULL;
}
static const char *vhost_secure(cmd_parms *cmd, void *dir, int arg)
{
priv_cfg *cfg = ap_get_module_config(cmd->server->module_config,
&privileges_module);
if (!arg) {
/* add basic privileges, excluding those covered by cgimode */
CFG_CHECK(priv_addset(cfg->priv, PRIV_FILE_LINK_ANY));
CFG_CHECK(priv_addset(cfg->priv, PRIV_PROC_INFO));
CFG_CHECK(priv_addset(cfg->priv, PRIV_PROC_SESSION));
}
return NULL;
}
static const char *vhost_cgimode(cmd_parms *cmd, void *dir, const char *arg)
{
priv_cfg *cfg = ap_get_module_config(cmd->server->module_config,
&privileges_module);
if (!strcasecmp(arg, "on")) {
/* default - nothing to do */
}
else if (!strcasecmp(arg, "off")) {
/* drop fork+exec privs */
CFG_CHECK(priv_delset(cfg->priv, PRIV_PROC_FORK));
CFG_CHECK(priv_delset(cfg->priv, PRIV_PROC_EXEC));
}
else if (!strcasecmp(arg, "secure")) {
/* deny privileges to CGI procs */
CFG_CHECK(priv_delset(cfg->child_priv, PRIV_PROC_FORK));
CFG_CHECK(priv_delset(cfg->child_priv, PRIV_PROC_EXEC));
CFG_CHECK(priv_delset(cfg->child_priv, PRIV_FILE_LINK_ANY));
CFG_CHECK(priv_delset(cfg->child_priv, PRIV_PROC_INFO));
CFG_CHECK(priv_delset(cfg->child_priv, PRIV_PROC_SESSION));
}
else {
return "VHostCGIMode must be On, Off or Secure";
}
return NULL;
}
static const char *dtraceenable(cmd_parms *cmd, void *dir, int arg)
{
const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
if (err != NULL) {
return err;
}
dtrace_enabled = arg;
return NULL;
}
static const char *privs_mode(cmd_parms *cmd, void *dir, const char *arg)
{
priv_mode mode = PRIV_UNSET;
if (!strcasecmp(arg, "FAST")) {
mode = PRIV_FAST;
}
else if (!strcasecmp(arg, "SECURE")) {
mode = PRIV_SECURE;
}
else if (!strcasecmp(arg, "SELECTIVE")) {
mode = PRIV_SELECTIVE;
}
if (cmd->path) {
/* In a directory context, set the per_dir_config */
priv_dir_cfg *cfg = dir;
cfg->mode = mode;
if ((mode == PRIV_UNSET) || (mode == PRIV_SELECTIVE)) {
return "PrivilegesMode in a Directory context must be FAST or SECURE";
}
}
else {
/* In a global or vhost context, set the server config */
priv_cfg *cfg = ap_get_module_config(cmd->server->module_config,
&privileges_module);
cfg->mode = mode;
if (mode == PRIV_UNSET) {
return "PrivilegesMode must be FAST, SECURE or SELECTIVE";
}
}
return NULL;
}
#ifdef BIG_SECURITY_HOLE
static const char *vhost_privs(cmd_parms *cmd, void *dir, const char *arg)
{
priv_cfg *cfg = ap_get_module_config(cmd->server->module_config,
&privileges_module);
const char *priv = arg;
if (*priv == '-') {
CFG_CHECK(priv_delset(cfg->priv, priv+1));
}
else if (*priv == '+') {
CFG_CHECK(priv_addset(cfg->priv, priv+1));
}
else {
priv_emptyset(cfg->priv);
CFG_CHECK(priv_addset(cfg->priv, priv));
}
return NULL;
}
static const char *vhost_cgiprivs(cmd_parms *cmd, void *dir, const char *arg)
{
priv_cfg *cfg = ap_get_module_config(cmd->server->module_config,
&privileges_module);
const char *priv = arg;
if (*priv == '-') {
CFG_CHECK(priv_delset(cfg->child_priv, priv+1));
}
else if (*priv == '+') {
CFG_CHECK(priv_addset(cfg->child_priv, priv+1));
}
else {
priv_emptyset(cfg->child_priv);
CFG_CHECK(priv_addset(cfg->child_priv, priv));
}
return NULL;
}
#endif
static const command_rec privileges_cmds[] = {
AP_INIT_TAKE1("VHostUser", vhost_user, NULL, RSRC_CONF,
"Userid under which the virtualhost will run"),
AP_INIT_TAKE1("VHostGroup", vhost_group, NULL, RSRC_CONF,
"Group under which the virtualhost will run"),
AP_INIT_FLAG("VHostSecure", vhost_secure, NULL, RSRC_CONF,
"Run in enhanced security mode (default ON)"),
AP_INIT_TAKE1("VHostCGIMode", vhost_cgimode, NULL, RSRC_CONF,
"Enable fork+exec for this virtualhost (Off|Secure|On)"),
AP_INIT_FLAG("DTracePrivileges", dtraceenable, NULL, RSRC_CONF,
"Enable DTrace"),
AP_INIT_TAKE1("PrivilegesMode", privs_mode, NULL, RSRC_CONF|ACCESS_CONF,
"tradeoff performance vs security (fast or secure)"),
#ifdef BIG_SECURITY_HOLE
AP_INIT_ITERATE("VHostPrivs", vhost_privs, NULL, RSRC_CONF,
"Privileges available in the (virtual) server"),
AP_INIT_ITERATE("VHostCGIPrivs", vhost_cgiprivs, NULL, RSRC_CONF,
"Privileges available to external programs"),
#endif
{NULL}
};
AP_DECLARE_MODULE(privileges) = {
STANDARD20_MODULE_STUFF,
privileges_create_dir_cfg,
privileges_merge_dir_cfg,
privileges_create_cfg,
privileges_merge_cfg,
privileges_cmds,
privileges_hooks
};