add clear_env option to FPM config

This makes it possible to leave the envoronment as is on startup and
pass all the variables to the workers.
The default value of clear_env is "yes", preserving previous behaviour.
Patch by Paul Annesley.

sapi/fpm/fpm/fpm_conf.c

@@ -148,6 +148,7 @@ static struct ini_value_parser_s ini_fpm_pool_options[] = {
 	{ "chroot",                    &fpm_conf_set_string,      WPO(chroot) },
 	{ "chdir",                     &fpm_conf_set_string,      WPO(chdir) },
 	{ "catch_workers_output",      &fpm_conf_set_boolean,     WPO(catch_workers_output) },
+	{ "clear_env",                 &fpm_conf_set_boolean,     WPO(clear_env) },
 	{ "security.limit_extensions", &fpm_conf_set_string,      WPO(security_limit_extensions) },
 #ifdef HAVE_APPARMOR
 	{ "apparmor_hat",              &fpm_conf_set_string,      WPO(apparmor_hat) },
@@ -606,6 +607,7 @@ static void *fpm_worker_pool_config_alloc() /* {{{ */
 	wp->config->listen_backlog = FPM_BACKLOG_DEFAULT;
 	wp->config->pm_process_idle_timeout = 10; /* 10s by default */
 	wp->config->process_priority = 64; /* 64 means unset */
+	wp->config->clear_env = 1;
 
 	if (!fpm_worker_all_pools) {
 		fpm_worker_all_pools = wp;
@@ -1606,6 +1608,7 @@ static void fpm_conf_dump() /* {{{ */
 		zlog(ZLOG_NOTICE, "\tchroot = %s",                     STR2STR(wp->config->chroot));
 		zlog(ZLOG_NOTICE, "\tchdir = %s",                      STR2STR(wp->config->chdir));
 		zlog(ZLOG_NOTICE, "\tcatch_workers_output = %s",       BOOL2STR(wp->config->catch_workers_output));
+		zlog(ZLOG_NOTICE, "\tclear_env = %s",                  BOOL2STR(wp->config->clear_env));
 		zlog(ZLOG_NOTICE, "\tsecurity.limit_extensions = %s",  wp->config->security_limit_extensions);
 
 		for (kv = wp->config->env; kv; kv = kv->next) {

sapi/fpm/fpm/fpm_conf.h

@@ -83,6 +83,7 @@ struct fpm_worker_pool_config_s {
 	char *chroot;
 	char *chdir;
 	int catch_workers_output;
+	int clear_env;
 	char *security_limit_extensions;
 	struct key_value_s *env;
 	struct key_value_s *php_admin_values;

sapi/fpm/fpm/fpm_env.c

@@ -143,7 +143,9 @@ int fpm_env_init_child(struct fpm_worker_pool_s *wp) /* {{{ */
 	fpm_env_setproctitle(title);
 	efree(title);
 
-	clearenv();
+	if (wp->config->clear_env) {
+		clearenv();
+	}
 
 	for (kv = wp->config->env; kv; kv = kv->next) {
 		setenv(kv->key, kv->value, 1);

sapi/fpm/php-fpm.conf.in

@@ -475,6 +475,15 @@ pm.max_spare_servers = 3
 ; Default Value: no
 ;catch_workers_output = yes
 
+; Clear environment in FPM workers
+; Prevents arbitrary environment variables from reaching FPM worker processes
+; by clearing the environment in workers before env vars specified in this
+; pool configuration are added.
+; Setting to "no" will make all environment variables available to PHP code
+; via getenv(), $_ENV and $_SERVER.
+; Default Value: yes
+;clear_env = no
+
 ; Limits the extensions of the main script FPM will allow to parse. This can
 ; prevent configuration mistakes on the web server side. You should only limit
 ; FPM to .php extensions to prevent malicious users to use other extensions to