1 files changed, 806 insertions, 0 deletions

diff --git a/src/master/master-settings.c b/src/master/master-settings.c
new file mode 100644
index 0000000..7cfaa35
--- /dev/null
+++ b/src/master/master-settings.c
@@ -0,0 +1,806 @@
+/* Copyright (c) 2005-2018 Dovecot authors, see the included COPYING file */
+
+#include "common.h"
+#include "array.h"
+#include "env-util.h"
+#include "istream.h"
+#include "net.h"
+#include "str.h"
+#include "ipwd.h"
+#include "mkdir-parents.h"
+#include "safe-mkdir.h"
+#include "restrict-process-size.h"
+#include "settings-parser.h"
+#include "master-settings.h"
+
+#include <stddef.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+
+static bool master_settings_verify(void *_set, pool_t pool,
+				   const char **error_r);
+
+extern const struct setting_parser_info service_setting_parser_info;
+
+#undef DEF
+#define DEF(type, name) \
+	SETTING_DEFINE_STRUCT_##type(#name, name, struct file_listener_settings)
+
+static const struct setting_define file_listener_setting_defines[] = {
+	DEF(STR, path),
+	DEF(UINT_OCT, mode),
+	DEF(STR, user),
+	DEF(STR, group),
+
+	SETTING_DEFINE_LIST_END
+};
+
+static const struct file_listener_settings file_listener_default_settings = {
+	.path = "",
+	.mode = 0600,
+	.user = "",
+	.group = "",
+};
+
+static const struct setting_parser_info file_listener_setting_parser_info = {
+	.defines = file_listener_setting_defines,
+	.defaults = &file_listener_default_settings,
+
+	.type_offset = offsetof(struct file_listener_settings, path),
+	.struct_size = sizeof(struct file_listener_settings),
+
+	.parent_offset = SIZE_MAX,
+	.parent = &service_setting_parser_info
+};
+
+#undef DEF
+#define DEF(type, name) \
+	SETTING_DEFINE_STRUCT_##type(#name, name, struct inet_listener_settings)
+
+static const struct setting_define inet_listener_setting_defines[] = {
+	DEF(STR, name),
+	DEF(STR, address),
+	DEF(IN_PORT, port),
+	DEF(BOOL, ssl),
+	DEF(BOOL, reuse_port),
+	DEF(BOOL, haproxy),
+
+	SETTING_DEFINE_LIST_END
+};
+
+static const struct inet_listener_settings inet_listener_default_settings = {
+	.name = "",
+	.address = "",
+	.port = 0,
+	.ssl = FALSE,
+	.reuse_port = FALSE,
+	.haproxy = FALSE
+};
+
+static const struct setting_parser_info inet_listener_setting_parser_info = {
+	.defines = inet_listener_setting_defines,
+	.defaults = &inet_listener_default_settings,
+
+	.type_offset = offsetof(struct inet_listener_settings, name),
+	.struct_size = sizeof(struct inet_listener_settings),
+
+	.parent_offset = SIZE_MAX,
+	.parent = &service_setting_parser_info
+};
+
+#undef DEF
+#undef DEFLIST_UNIQUE
+#define DEF(type, name) \
+	SETTING_DEFINE_STRUCT_##type(#name, name, struct service_settings)
+#define DEFLIST_UNIQUE(field, name, defines) \
+	{ .type = SET_DEFLIST_UNIQUE, .key = name, \
+	  .offset = offsetof(struct service_settings, field), \
+	  .list_info = defines }
+
+static const struct setting_define service_setting_defines[] = {
+	DEF(STR, name),
+	DEF(STR, protocol),
+	DEF(STR, type),
+	DEF(STR, executable),
+	DEF(STR, user),
+	DEF(STR, group),
+	DEF(STR, privileged_group),
+	DEF(STR, extra_groups),
+	DEF(STR, chroot),
+
+	DEF(BOOL, drop_priv_before_exec),
+
+	DEF(UINT, process_min_avail),
+	DEF(UINT, process_limit),
+	DEF(UINT, client_limit),
+	DEF(UINT, service_count),
+	DEF(TIME, idle_kill),
+	DEF(SIZE, vsz_limit),
+
+	DEFLIST_UNIQUE(unix_listeners, "unix_listener",
+		       &file_listener_setting_parser_info),
+	DEFLIST_UNIQUE(fifo_listeners, "fifo_listener",
+		       &file_listener_setting_parser_info),
+	DEFLIST_UNIQUE(inet_listeners, "inet_listener",
+		       &inet_listener_setting_parser_info),
+
+	SETTING_DEFINE_LIST_END
+};
+
+static const struct service_settings service_default_settings = {
+	.name = "",
+	.protocol = "",
+	.type = "",
+	.executable = "",
+	.user = "",
+	.group = "",
+	.privileged_group = "",
+	.extra_groups = "",
+	.chroot = "",
+
+	.drop_priv_before_exec = FALSE,
+
+	.process_min_avail = 0,
+	.process_limit = 0,
+	.client_limit = 0,
+	.service_count = 0,
+	.idle_kill = 0,
+	.vsz_limit = UOFF_T_MAX,
+
+	.unix_listeners = ARRAY_INIT,
+	.fifo_listeners = ARRAY_INIT,
+	.inet_listeners = ARRAY_INIT
+};
+
+const struct setting_parser_info service_setting_parser_info = {
+	.defines = service_setting_defines,
+	.defaults = &service_default_settings,
+
+	.type_offset = offsetof(struct service_settings, name),
+	.struct_size = sizeof(struct service_settings),
+
+	.parent_offset = offsetof(struct service_settings, master_set),
+	.parent = &master_setting_parser_info
+};
+
+#undef DEF
+#undef DEFLIST_UNIQUE
+#define DEF(type, name) \
+	SETTING_DEFINE_STRUCT_##type(#name, name, struct master_settings)
+#define DEFLIST_UNIQUE(field, name, defines) \
+	{ .type = SET_DEFLIST_UNIQUE, .key = name, \
+	  .offset = offsetof(struct master_settings, field), \
+	  .list_info = defines }
+
+static const struct setting_define master_setting_defines[] = {
+	DEF(STR, base_dir),
+	DEF(STR, state_dir),
+	DEF(STR, libexec_dir),
+	DEF(STR, instance_name),
+	DEF(STR, protocols),
+	DEF(STR, listen),
+	DEF(ENUM, ssl),
+	DEF(STR, default_internal_user),
+	DEF(STR, default_internal_group),
+	DEF(STR, default_login_user),
+	DEF(UINT, default_process_limit),
+	DEF(UINT, default_client_limit),
+	DEF(TIME, default_idle_kill),
+	DEF(SIZE, default_vsz_limit),
+
+	DEF(BOOL, version_ignore),
+
+	DEF(UINT, first_valid_uid),
+	DEF(UINT, last_valid_uid),
+	DEF(UINT, first_valid_gid),
+	DEF(UINT, last_valid_gid),
+
+	DEFLIST_UNIQUE(services, "service", &service_setting_parser_info),
+
+	SETTING_DEFINE_LIST_END
+};
+
+static const struct master_settings master_default_settings = {
+	.base_dir = PKG_RUNDIR,
+	.state_dir = PKG_STATEDIR,
+	.libexec_dir = PKG_LIBEXECDIR,
+	.instance_name = PACKAGE,
+	.protocols = "imap pop3 lmtp",
+	.listen = "*, ::",
+	.ssl = "yes:no:required",
+	.default_internal_user = "dovecot",
+	.default_internal_group = "dovecot",
+	.default_login_user = "dovenull",
+	.default_process_limit = 100,
+	.default_client_limit = 1000,
+	.default_idle_kill = 60,
+	.default_vsz_limit = 256*1024*1024,
+
+	.version_ignore = FALSE,
+
+	.first_valid_uid = 500,
+	.last_valid_uid = 0,
+	.first_valid_gid = 1,
+	.last_valid_gid = 0,
+
+#ifndef CONFIG_BINARY
+	.services = ARRAY_INIT
+#else
+	.services = { { &config_all_services_buf,
+			     sizeof(struct service_settings *) } },
+#endif
+};
+
+const struct setting_parser_info master_setting_parser_info = {
+	.module_name = "master",
+	.defines = master_setting_defines,
+	.defaults = &master_default_settings,
+
+	.type_offset = SIZE_MAX,
+	.struct_size = sizeof(struct master_settings),
+
+	.parent_offset = SIZE_MAX,
+
+	.check_func = master_settings_verify
+};
+
+/* <settings checks> */
+static void
+expand_user(const char **user, enum service_user_default *default_r,
+	    const struct master_settings *set)
+{
+	/* $variable expansion is typically done by doveconf, but these
+	   variables can come from built-in settings, so we need to expand
+	   them here */
+	if (strcmp(*user, "$default_internal_user") == 0) {
+		*user = set->default_internal_user;
+		*default_r = SERVICE_USER_DEFAULT_INTERNAL;
+	} else if (strcmp(*user, "$default_login_user") == 0) {
+		*user = set->default_login_user;
+		*default_r = SERVICE_USER_DEFAULT_LOGIN;
+	} else {
+		*default_r = SERVICE_USER_DEFAULT_NONE;
+	}
+}
+
+static void
+expand_group(const char **group, const struct master_settings *set)
+{
+	/* $variable expansion is typically done by doveconf, but these
+	   variables can come from built-in settings, so we need to expand
+	   them here */
+	if (strcmp(*group, "$default_internal_group") == 0)
+		*group = set->default_internal_group;
+}
+
+static bool
+fix_file_listener_paths(ARRAY_TYPE(file_listener_settings) *l,
+			pool_t pool, const struct master_settings *master_set,
+			ARRAY_TYPE(const_string) *all_listeners,
+			const char **error_r)
+{
+	struct file_listener_settings *set;
+	size_t base_dir_len = strlen(master_set->base_dir);
+	enum service_user_default user_default;
+
+	if (!array_is_created(l))
+		return TRUE;
+
+	array_foreach_elem(l, set) {
+		if (set->path[0] == '\0') {
+			*error_r = "path must not be empty";
+			return FALSE;
+		}
+
+		expand_user(&set->user, &user_default, master_set);
+		expand_group(&set->group, master_set);
+		if (*set->path != '/') {
+			set->path = p_strconcat(pool, master_set->base_dir, "/",
+						set->path, NULL);
+		} else if (strncmp(set->path, master_set->base_dir,
+				   base_dir_len) == 0 &&
+			   set->path[base_dir_len] == '/') {
+			i_warning("You should remove base_dir prefix from "
+				  "unix_listener: %s", set->path);
+		}
+		if (set->mode != 0)
+			array_push_back(all_listeners, &set->path);
+	}
+	return TRUE;
+}
+
+static void add_inet_listeners(ARRAY_TYPE(inet_listener_settings) *l,
+			       ARRAY_TYPE(const_string) *all_listeners)
+{
+	struct inet_listener_settings *set;
+	const char *str;
+
+	if (!array_is_created(l))
+		return;
+
+	array_foreach_elem(l, set) {
+		if (set->port != 0) {
+			str = t_strdup_printf("%u:%s", set->port, set->address);
+			array_push_back(all_listeners, &str);
+		}
+	}
+}
+
+static bool master_settings_parse_type(struct service_settings *set,
+				       const char **error_r)
+{
+	if (*set->type == '\0')
+		set->parsed_type = SERVICE_TYPE_UNKNOWN;
+	else if (strcmp(set->type, "log") == 0)
+		set->parsed_type = SERVICE_TYPE_LOG;
+	else if (strcmp(set->type, "config") == 0)
+		set->parsed_type = SERVICE_TYPE_CONFIG;
+	else if (strcmp(set->type, "anvil") == 0)
+		set->parsed_type = SERVICE_TYPE_ANVIL;
+	else if (strcmp(set->type, "login") == 0)
+		set->parsed_type = SERVICE_TYPE_LOGIN;
+	else if (strcmp(set->type, "startup") == 0)
+		set->parsed_type = SERVICE_TYPE_STARTUP;
+	else if (strcmp(set->type, "worker") == 0)
+		set->parsed_type = SERVICE_TYPE_WORKER;
+	else {
+		*error_r = t_strconcat("Unknown service type: ",
+				       set->type, NULL);
+		return FALSE;
+	}
+	return TRUE;
+}
+
+static void service_set_login_dump_core(struct service_settings *set)
+{
+	const char *p;
+
+	if (set->parsed_type != SERVICE_TYPE_LOGIN)
+		return;
+
+	p = strstr(set->executable, " -D");
+	if (p != NULL && (p[3] == '\0' || p[3] == ' '))
+		set->login_dump_core = TRUE;
+}
+
+static bool
+services_have_protocol(struct master_settings *set, const char *name)
+{
+	struct service_settings *service;
+
+	array_foreach_elem(&set->services, service) {
+		if (strcmp(service->protocol, name) == 0)
+			return TRUE;
+	}
+	return FALSE;
+}
+
+#ifdef CONFIG_BINARY
+static const struct service_settings *
+master_default_settings_get_service(const char *name)
+{
+	extern struct master_settings master_default_settings;
+	struct service_settings *set;
+
+	array_foreach_elem(&master_default_settings.services, set) {
+		if (strcmp(set->name, name) == 0)
+			return set;
+	}
+	return NULL;
+}
+#endif
+
+static unsigned int
+service_get_client_limit(struct master_settings *set, const char *name)
+{
+	struct service_settings *service;
+
+	array_foreach_elem(&set->services, service) {
+		if (strcmp(service->name, name) == 0) {
+			if (service->client_limit != 0)
+				return service->client_limit;
+			else
+				return set->default_client_limit;
+		}
+	}
+	return set->default_client_limit;
+}
+
+static bool
+master_settings_verify(void *_set, pool_t pool, const char **error_r)
+{
+	static bool warned_auth = FALSE, warned_anvil = FALSE;
+	struct master_settings *set = _set;
+	struct service_settings *const *services;
+	const char *const *strings;
+	ARRAY_TYPE(const_string) all_listeners;
+	struct passwd pw;
+	unsigned int i, j, count, client_limit, process_limit;
+	unsigned int max_auth_client_processes, max_anvil_client_processes;
+	string_t *max_auth_client_processes_reason = t_str_new(64);
+	string_t *max_anvil_client_processes_reason = t_str_new(64);
+	size_t len;
+#ifdef CONFIG_BINARY
+	const struct service_settings *default_service;
+#else
+	rlim_t fd_limit;
+	const char *max_client_limit_source = "default_client_limit";
+	unsigned int max_client_limit = set->default_client_limit;
+#endif
+
+	if (*set->listen == '\0') {
+		*error_r = "listen can't be set empty";
+		return FALSE;
+	}
+
+	len = strlen(set->base_dir);
+	if (len > 0 && set->base_dir[len-1] == '/') {
+		/* drop trailing '/' */
+		set->base_dir = p_strndup(pool, set->base_dir, len - 1);
+	}
+
+	if (set->last_valid_uid != 0 &&
+	    set->first_valid_uid > set->last_valid_uid) {
+		*error_r = "first_valid_uid can't be larger than last_valid_uid";
+		return FALSE;
+	}
+	if (set->last_valid_gid != 0 &&
+	    set->first_valid_gid > set->last_valid_gid) {
+		*error_r = "first_valid_gid can't be larger than last_valid_gid";
+		return FALSE;
+	}
+
+	if (i_getpwnam(set->default_login_user, &pw) == 0) {
+		*error_r = t_strdup_printf("default_login_user doesn't exist: %s",
+					   set->default_login_user);
+		return FALSE;
+	}
+	if (i_getpwnam(set->default_internal_user, &pw) == 0) {
+		*error_r = t_strdup_printf("default_internal_user doesn't exist: %s",
+					   set->default_internal_user);
+		return FALSE;
+	}
+
+	/* check that we have at least one service. the actual service
+	   structure validity is checked later while creating them. */
+	if (!array_is_created(&set->services) ||
+	    array_count(&set->services) == 0) {
+		*error_r = "No services defined";
+		return FALSE;
+	}
+	services = array_get(&set->services, &count);
+	for (i = 0; i < count; i++) {
+		struct service_settings *service = services[i];
+
+		if (*service->name == '\0') {
+			*error_r = t_strdup_printf(
+				"Service #%d is missing name", i);
+			return FALSE;
+		}
+		if (!master_settings_parse_type(service, error_r))
+			return FALSE;
+		for (j = 0; j < i; j++) {
+			if (strcmp(service->name, services[j]->name) == 0) {
+				*error_r = t_strdup_printf(
+					"Duplicate service name: %s",
+					service->name);
+				return FALSE;
+			}
+		}
+		expand_user(&service->user, &service->user_default, set);
+		expand_group(&service->extra_groups, set);
+		service_set_login_dump_core(service);
+	}
+	set->protocols_split = p_strsplit_spaces(pool, set->protocols, " ");
+	if (set->protocols_split[0] != NULL &&
+	    strcmp(set->protocols_split[0], "none") == 0 &&
+	    set->protocols_split[1] == NULL)
+		set->protocols_split[0] = NULL;
+
+	for (i = 0; set->protocols_split[i] != NULL; i++) {
+		if (!services_have_protocol(set, set->protocols_split[i])) {
+			*error_r = t_strdup_printf("protocols: "
+						   "Unknown protocol: %s",
+						   set->protocols_split[i]);
+			return FALSE;
+		}
+	}
+	t_array_init(&all_listeners, 64);
+	max_auth_client_processes = 0;
+	max_anvil_client_processes = 2; /* blocking, nonblocking pipes */
+	for (i = 0; i < count; i++) {
+		struct service_settings *service = services[i];
+
+		if (*service->protocol != '\0' &&
+		    !str_array_find((const char **)set->protocols_split,
+				    service->protocol)) {
+			/* protocol not enabled, ignore its settings */
+			continue;
+		}
+
+		if (*service->executable != '/' &&
+		    *service->executable != '\0') {
+			service->executable =
+				p_strconcat(pool, set->libexec_dir, "/",
+					    service->executable, NULL);
+		}
+		if (*service->chroot != '/' && *service->chroot != '\0') {
+			service->chroot =
+				p_strconcat(pool, set->base_dir, "/",
+					    service->chroot, NULL);
+		}
+		if (service->drop_priv_before_exec &&
+		    *service->chroot != '\0') {
+			*error_r = t_strdup_printf("service(%s): "
+				"drop_priv_before_exec=yes can't be "
+				"used with chroot", service->name);
+			return FALSE;
+		}
+		process_limit = service->process_limit;
+		if (process_limit == 0)
+			process_limit = set->default_process_limit;
+		if (service->process_min_avail > process_limit) {
+			*error_r = t_strdup_printf("service(%s): "
+				"process_min_avail is higher than process_limit",
+				service->name);
+			return FALSE;
+		}
+		if (service->vsz_limit < 1024*1024 && service->vsz_limit != 0) {
+			*error_r = t_strdup_printf("service(%s): "
+				"vsz_limit is too low", service->name);
+			return FALSE;
+		}
+
+#ifdef CONFIG_BINARY
+		default_service =
+			master_default_settings_get_service(service->name);
+		if (default_service != NULL &&
+		    default_service->process_limit_1 && process_limit > 1) {
+			*error_r = t_strdup_printf("service(%s): "
+				"process_limit must be 1", service->name);
+			return FALSE;
+		}
+#else
+		if (max_client_limit < service->client_limit) {
+			max_client_limit = service->client_limit;
+			max_client_limit_source = t_strdup_printf(
+				"service %s { client_limit }", service->name);
+		}
+#endif
+
+		if (*service->protocol != '\0') {
+			/* each imap/pop3/lmtp process can use up a connection,
+			   although if service_count=1 it's only temporary.
+			   imap-hibernate doesn't do any auth lookups. */
+			if ((service->service_count != 1 ||
+			     strcmp(service->type, "login") == 0) &&
+			    strcmp(service->name, "imap-hibernate") != 0) {
+				str_printfa(max_auth_client_processes_reason,
+					    " + service %s { process_limit=%u }",
+					    service->name, process_limit);
+				max_auth_client_processes += process_limit;
+			}
+		}
+		if (strcmp(service->type, "login") == 0 ||
+		    strcmp(service->name, "auth") == 0) {
+			max_anvil_client_processes += process_limit;
+			str_printfa(max_anvil_client_processes_reason,
+				    " + service %s { process_limit=%u }",
+				    service->name, process_limit);
+		}
+
+		if (!fix_file_listener_paths(&service->unix_listeners, pool,
+					     set, &all_listeners, error_r)) {
+			*error_r = t_strdup_printf("service(%s): unix_listener: %s",
+						   service->name, *error_r);
+			return FALSE;
+		}
+		if (!fix_file_listener_paths(&service->fifo_listeners, pool,
+					     set, &all_listeners, error_r)) {
+			*error_r = t_strdup_printf("service(%s): fifo_listener: %s",
+						   service->name, *error_r);
+			return FALSE;
+		}
+		add_inet_listeners(&service->inet_listeners, &all_listeners);
+	}
+
+	client_limit = service_get_client_limit(set, "auth");
+	if (client_limit < max_auth_client_processes && !warned_auth) {
+		warned_auth = TRUE;
+		str_delete(max_auth_client_processes_reason, 0, 3);
+		i_warning("service auth { client_limit=%u } is lower than "
+			  "required under max. load (%u). "
+			  "Counted for protocol services with service_count != 1: %s",
+			  client_limit, max_auth_client_processes,
+			  str_c(max_auth_client_processes_reason));
+	}
+
+	client_limit = service_get_client_limit(set, "anvil");
+	if (client_limit < max_anvil_client_processes && !warned_anvil) {
+		warned_anvil = TRUE;
+		str_delete(max_anvil_client_processes_reason, 0, 3);
+		i_warning("service anvil { client_limit=%u } is lower than "
+			  "required under max. load (%u). Counted with: %s",
+			  client_limit, max_anvil_client_processes,
+			  str_c(max_anvil_client_processes_reason));
+	}
+#ifndef CONFIG_BINARY
+	if (restrict_get_fd_limit(&fd_limit) == 0 &&
+	    fd_limit < (rlim_t)max_client_limit) {
+		i_warning("fd limit (ulimit -n) is lower than required "
+			  "under max. load (%u < %u), because of %s",
+			  (unsigned int)fd_limit, max_client_limit,
+			  max_client_limit_source);
+	}
+#endif
+
+	/* check for duplicate listeners */
+	array_sort(&all_listeners, i_strcmp_p);
+	strings = array_get(&all_listeners, &count);
+	for (i = 1; i < count; i++) {
+		if (strcmp(strings[i-1], strings[i]) == 0) {
+			*error_r = t_strdup_printf("duplicate listener: %s",
+						   strings[i]);
+			return FALSE;
+		}
+	}
+	return TRUE;
+}
+/* </settings checks> */
+
+static bool
+login_want_core_dumps(const struct master_settings *set, gid_t *gid_r)
+{
+	struct service_settings *service;
+	const char *error;
+	bool cores = FALSE;
+	uid_t uid;
+
+	*gid_r = (gid_t)-1;
+
+	array_foreach_elem(&set->services, service) {
+		if (service->parsed_type == SERVICE_TYPE_LOGIN) {
+			if (service->login_dump_core)
+				cores = TRUE;
+			(void)get_uidgid(service->user, &uid, gid_r, &error);
+			if (*service->group != '\0')
+				(void)get_gid(service->group, gid_r, &error);
+		}
+	}
+	return cores;
+}
+
+static bool
+settings_have_auth_unix_listeners_in(const struct master_settings *set,
+				     const char *dir)
+{
+	struct service_settings *service;
+	struct file_listener_settings *u;
+	size_t dir_len = strlen(dir);
+
+	array_foreach_elem(&set->services, service) {
+		if (array_is_created(&service->unix_listeners)) {
+			array_foreach_elem(&service->unix_listeners, u) {
+				if (strncmp(u->path, dir, dir_len) == 0 &&
+				    u->path[dir_len] == '/')
+					return TRUE;
+			}
+		}
+	}
+	return FALSE;
+}
+
+static void unlink_sockets(const char *path, const char *prefix)
+{
+	DIR *dirp;
+	struct dirent *dp;
+	struct stat st;
+	string_t *str;
+	size_t prefix_len;
+
+	dirp = opendir(path);
+	if (dirp == NULL) {
+		i_error("opendir(%s) failed: %m", path);
+		return;
+	}
+
+	prefix_len = strlen(prefix);
+	str = t_str_new(256);
+	while ((dp = readdir(dirp)) != NULL) {
+		if (dp->d_name[0] == '.')
+			continue;
+
+		if (strncmp(dp->d_name, prefix, prefix_len) != 0)
+			continue;
+
+		str_truncate(str, 0);
+		str_printfa(str, "%s/%s", path, dp->d_name);
+		if (lstat(str_c(str), &st) < 0) {
+			if (errno != ENOENT)
+				i_error("lstat(%s) failed: %m", str_c(str));
+			continue;
+		}
+		if (!S_ISSOCK(st.st_mode))
+			continue;
+
+		/* try to avoid unlinking sockets if someone's already
+		   listening in them. do this only at startup, because
+		   when SIGHUPing a child process might catch the new
+		   connection before it notices that it's supposed
+		   to die. */
+		if (!startup_finished) {
+			int fd = net_connect_unix(str_c(str));
+			if (fd != -1 || errno != ECONNREFUSED) {
+				i_fatal("Dovecot is already running? "
+					"Socket already exists: %s",
+					str_c(str));
+			}
+		}
+
+		i_unlink_if_exists(str_c(str));
+	}
+	(void)closedir(dirp);
+}
+
+static void
+mkdir_login_dir(const struct master_settings *set, const char *login_dir)
+{
+	mode_t mode;
+	gid_t gid;
+
+	if (settings_have_auth_unix_listeners_in(set, login_dir)) {
+		/* we are not using external authentication, so make sure the
+		   login directory exists with correct permissions and it's
+		   empty. with external auth we wouldn't want to delete
+		   existing sockets or break the permissions required by the
+		   auth server. */
+		mode = login_want_core_dumps(set, &gid) ? 0770 : 0750;
+		if (safe_mkdir(login_dir, mode, master_uid, gid) == 0) {
+			i_warning("Corrected permissions for login directory "
+				  "%s", login_dir);
+		}
+
+		unlink_sockets(login_dir, "");
+	} else {
+		/* still make sure that login directory exists */
+		if (mkdir(login_dir, 0755) < 0 && errno != EEXIST)
+			i_fatal("mkdir(%s) failed: %m", login_dir);
+	}
+}
+
+void master_settings_do_fixes(const struct master_settings *set)
+{
+	const char *empty_dir;
+	struct stat st;
+
+	/* since base dir is under /var/run by default, it may have been
+	   deleted. */
+	if (mkdir_parents(set->base_dir, 0755) < 0 && errno != EEXIST)
+		i_fatal("mkdir(%s) failed: %m", set->base_dir);
+	/* allow base_dir to be a symlink, so don't use lstat() */
+	if (stat(set->base_dir, &st) < 0)
+		i_fatal("stat(%s) failed: %m", set->base_dir);
+	if (!S_ISDIR(st.st_mode))
+		i_fatal("%s is not a directory", set->base_dir);
+	if ((st.st_mode & 0755) != 0755) {
+		i_warning("Fixing permissions of %s to be world-readable",
+			  set->base_dir);
+		if (chmod(set->base_dir, 0755) < 0)
+			i_error("chmod(%s) failed: %m", set->base_dir);
+	}
+
+	/* Make sure our permanent state directory exists */
+	if (mkdir_parents(set->state_dir, 0755) < 0 && errno != EEXIST)
+		i_fatal("mkdir(%s) failed: %m", set->state_dir);
+
+	mkdir_login_dir(set, t_strconcat(set->base_dir, "/login", NULL));
+	mkdir_login_dir(set, t_strconcat(set->base_dir, "/token-login", NULL));
+
+	empty_dir = t_strconcat(set->base_dir, "/empty", NULL);
+	if (safe_mkdir(empty_dir, 0755, master_uid, getegid()) == 0) {
+		i_warning("Corrected permissions for empty directory "
+			  "%s", empty_dir);
+	}
+}