/* SPDX-License-Identifier: GPL-2.0-or-later */ /* * Copyright (C) 2004 - 2016 Red Hat, Inc. * Copyright (C) 2005 - 2008 Novell, Inc. */ #include "src/core/nm-default-daemon.h" #include "nm-firewall-utils.h" #include "libnm-glib-aux/nm-str-buf.h" #include "libnm-glib-aux/nm-io-utils.h" #include "libnm-platform/nm-platform.h" #include "nm-config.h" #include "NetworkManagerUtils.h" /*****************************************************************************/ static const struct { const char *name; const char *path; } FirewallBackends[] = { [NM_FIREWALL_BACKEND_NONE - 1] = { .name = "none", }, [NM_FIREWALL_BACKEND_NFTABLES - 1] = { .name = "nftables", .path = NFT_PATH, }, [NM_FIREWALL_BACKEND_IPTABLES - 1] = { .name = "iptables", .path = IPTABLES_PATH, }, }; /*****************************************************************************/ #define _SHARE_IPTABLES_SUBNET_TO_STR_LEN (INET_ADDRSTRLEN + 1 + 2 + 1) static const char * _share_iptables_subnet_to_str(char buf[static _SHARE_IPTABLES_SUBNET_TO_STR_LEN], in_addr_t addr, guint8 plen) { char buf_addr[INET_ADDRSTRLEN]; in_addr_t netmask; int l; netmask = _nm_utils_ip4_prefix_to_netmask(plen); l = g_snprintf(buf, _SHARE_IPTABLES_SUBNET_TO_STR_LEN, "%s/%u", _nm_utils_inet4_ntop(addr & netmask, buf_addr), plen); nm_assert(l < _SHARE_IPTABLES_SUBNET_TO_STR_LEN); return buf; } static char * _share_iptables_get_name(gboolean is_iptables_chain, const char *prefix, const char *ip_iface) { NMStrBuf strbuf = NM_STR_BUF_INIT(NM_UTILS_GET_NEXT_REALLOC_SIZE_40, FALSE); gsize ip_iface_len; nm_assert(prefix); nm_assert(ip_iface); /* This function is used to generate iptables chain names and comments. * Chain names must be shorter than 29 chars. Comments don't have this * limitation. * * Below we sanitize the ip_iface. If it's all benign, we use * - either "-$IP_IFACE" (at most 16 chars) * - otherwise, we base64 encode the name as "$(base64 $IP_IFACE)", at * most 20 chars. * * Since for benign names we already add a '-', prefix probably should not * contain a '-'. The '-' is necessary to distinguish between base64 encoding * an plain name. * * That means, for chain names the prefix must be at most 8 chars long. */ nm_assert(!is_iptables_chain || (strlen(prefix) <= 8)); nm_str_buf_append(&strbuf, prefix); ip_iface_len = strlen(ip_iface); G_STATIC_ASSERT_EXPR(NMP_IFNAMSIZ == 16); if (ip_iface_len >= NMP_IFNAMSIZ) { nm_assert_not_reached(); ip_iface_len = NMP_IFNAMSIZ - 1; } if (NM_STRCHAR_ALL(ip_iface, ch, (ch >= '0' && ch <= '9') || (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || NM_IN_SET(ch, '.', '_', '-', '+'))) { nm_str_buf_append_c(&strbuf, '-'); nm_str_buf_append(&strbuf, ip_iface); } else { gs_free char *s = NULL; s = g_base64_encode((const guchar *) ip_iface, ip_iface_len); nm_str_buf_append(&strbuf, s); } return nm_str_buf_finalize(&strbuf, NULL); } static gboolean _share_iptables_call_v(const char *const *argv) { gs_free_error GError *error = NULL; gs_free char *argv_str = NULL; int status; nm_log_dbg(LOGD_SHARING, "iptables: %s", (argv_str = g_strjoinv(" ", (char **) argv))); if (!g_spawn_sync("/", (char **) argv, (char **) NM_PTRARRAY_EMPTY(const char *), G_SPAWN_STDOUT_TO_DEV_NULL | G_SPAWN_STDERR_TO_DEV_NULL, NULL, NULL, NULL, NULL, &status, &error)) { nm_log_warn(LOGD_SHARING, "iptables: error executing command %s: %s", argv[0], error->message); return FALSE; } if (!g_spawn_check_exit_status(status, &error)) { nm_log_warn(LOGD_SHARING, "iptables: command %s failed: %s", argv[0], error->message); return FALSE; } return TRUE; } #define _share_iptables_call(...) _share_iptables_call_v(NM_MAKE_STRV(__VA_ARGS__)) static gboolean _share_iptables_chain_op(const char *table, const char *chain, const char *op) { return _share_iptables_call("" IPTABLES_PATH "", "--table", table, op, chain); } static gboolean _share_iptables_chain_delete(const char *table, const char *chain) { _share_iptables_chain_op(table, chain, "--flush"); return _share_iptables_chain_op(table, chain, "--delete-chain"); } static gboolean _share_iptables_chain_add(const char *table, const char *chain) { if (_share_iptables_chain_op(table, chain, "--new-chain")) return TRUE; _share_iptables_chain_delete(table, chain); return _share_iptables_chain_op(table, chain, "--new-chain"); } static void _share_iptables_set_masquerade(gboolean add, const char *ip_iface, in_addr_t addr, guint8 plen) { char str_subnet[_SHARE_IPTABLES_SUBNET_TO_STR_LEN]; gs_free char *comment_name = NULL; comment_name = _share_iptables_get_name(FALSE, "nm-shared", ip_iface); _share_iptables_subnet_to_str(str_subnet, addr, plen); _share_iptables_call("" IPTABLES_PATH "", "--table", "nat", add ? "--insert" : "--delete", "POSTROUTING", "--source", str_subnet, "!", "--destination", str_subnet, "--jump", "MASQUERADE", "-m", "comment", "--comment", comment_name); } static void _share_iptables_set_shared_chains_add(const char *chain_input, const char *chain_forward, const char *ip_iface, in_addr_t addr, guint plen) { const char *const input_params[][2] = { { "tcp", "67", }, { "udp", "67", }, { "tcp", "53", }, { "udp", "53", }, }; char str_subnet[_SHARE_IPTABLES_SUBNET_TO_STR_LEN]; int i; _share_iptables_subnet_to_str(str_subnet, addr, plen); _share_iptables_chain_add("filter", chain_input); for (i = 0; i < (int) G_N_ELEMENTS(input_params); i++) { _share_iptables_call("" IPTABLES_PATH "", "--table", "filter", "--append", chain_input, "--protocol", input_params[i][0], "--destination-port", input_params[i][1], "--jump", "ACCEPT"); } _share_iptables_chain_add("filter", chain_forward); _share_iptables_call("" IPTABLES_PATH "", "--table", "filter", "--append", chain_forward, "--destination", str_subnet, "--out-interface", ip_iface, "--match", "state", "--state", "ESTABLISHED,RELATED", "--jump", "ACCEPT"); _share_iptables_call("" IPTABLES_PATH "", "--table", "filter", "--append", chain_forward, "--source", str_subnet, "--in-interface", ip_iface, "--jump", "ACCEPT"); _share_iptables_call("" IPTABLES_PATH "", "--table", "filter", "--append", chain_forward, "--in-interface", ip_iface, "--out-interface", ip_iface, "--jump", "ACCEPT"); _share_iptables_call("" IPTABLES_PATH "", "--table", "filter", "--append", chain_forward, "--out-interface", ip_iface, "--jump", "REJECT"); _share_iptables_call("" IPTABLES_PATH "", "--table", "filter", "--append", chain_forward, "--in-interface", ip_iface, "--jump", "REJECT"); } static void _share_iptables_set_shared_chains_delete(const char *chain_input, const char *chain_forward) { _share_iptables_chain_delete("filter", chain_input); _share_iptables_chain_delete("filter", chain_forward); } _nm_unused static void _share_iptables_set_shared(gboolean add, const char *ip_iface, in_addr_t addr, guint plen) { gs_free char *comment_name = NULL; gs_free char *chain_input = NULL; gs_free char *chain_forward = NULL; comment_name = _share_iptables_get_name(FALSE, "nm-shared", ip_iface); chain_input = _share_iptables_get_name(TRUE, "nm-sh-in", ip_iface); chain_forward = _share_iptables_get_name(TRUE, "nm-sh-fw", ip_iface); if (add) _share_iptables_set_shared_chains_add(chain_input, chain_forward, ip_iface, addr, plen); _share_iptables_call("" IPTABLES_PATH "", "--table", "filter", add ? "--insert" : "--delete", "INPUT", "--in-interface", ip_iface, "--jump", chain_input, "-m", "comment", "--comment", comment_name); _share_iptables_call("" IPTABLES_PATH "", "--table", "filter", add ? "--insert" : "--delete", "FORWARD", "--jump", chain_forward, "-m", "comment", "--comment", comment_name); if (!add) _share_iptables_set_shared_chains_delete(chain_input, chain_forward); } /*****************************************************************************/ typedef struct { GTask *task; GSubprocess *subprocess; GSource *timeout_source; GCancellable *intern_cancellable; char *identifier; gulong cancellable_id; } FwNftCallData; static void _fw_nft_call_data_free(FwNftCallData *call_data, GError *error_take) { nm_clear_g_signal_handler(g_task_get_cancellable(call_data->task), &call_data->cancellable_id); nm_clear_g_cancellable(&call_data->intern_cancellable); nm_clear_g_source_inst(&call_data->timeout_source); if (error_take) g_task_return_error(call_data->task, error_take); else g_task_return_boolean(call_data->task, TRUE); g_object_unref(call_data->task); nm_g_object_unref(call_data->subprocess); g_free(call_data->identifier); nm_g_slice_free(call_data); } static void _fw_nft_call_communicate_cb(GObject *source, GAsyncResult *result, gpointer user_data) { FwNftCallData *call_data = user_data; gs_free_error GError *error = NULL; gs_unref_bytes GBytes *stdout_buf = NULL; gs_unref_bytes GBytes *stderr_buf = NULL; nm_assert(source == (gpointer) call_data->subprocess); if (!g_subprocess_communicate_finish(G_SUBPROCESS(source), result, &stdout_buf, &stderr_buf, &error)) { /* on any error, the process might still be running. We need to abort it in * the background... */ if (!nm_utils_error_is_cancelled(error)) { nm_log_dbg(LOGD_SHARING, "firewall: nft[%s]: communication failed: %s. Kill process", call_data->identifier, error->message); } else if (!call_data->timeout_source) { nm_log_dbg(LOGD_SHARING, "firewall: ntf[%s]: communication timed out. Kill process", call_data->identifier); nm_clear_error(&error); nm_utils_error_set(&error, NM_UTILS_ERROR_UNKNOWN, "timeout communicating with nft"); } else { nm_log_dbg(LOGD_SHARING, "firewall: ntf[%s]: communication cancelled. Kill process", call_data->identifier); } { _nm_unused nm_auto_pop_gmaincontext GMainContext *main_context = nm_g_main_context_push_thread_default_if_necessary(NULL); nm_shutdown_wait_obj_register_object(call_data->subprocess, "nft-terminate"); G_STATIC_ASSERT_EXPR(200 < NM_SHUTDOWN_TIMEOUT_ADDITIONAL_MSEC * 2 / 3); nm_g_subprocess_terminate_in_background(call_data->subprocess, 200); } } else if (g_subprocess_get_successful(call_data->subprocess)) { nm_log_dbg(LOGD_SHARING, "firewall: nft[%s]: command successful", call_data->identifier); } else { gs_free char *ss_stdout = NULL; gs_free char *ss_stderr = NULL; gboolean print_stdout = (stdout_buf && g_bytes_get_size(stdout_buf) > 0); gboolean print_stderr = (stderr_buf && g_bytes_get_size(stderr_buf) > 0); nm_log_warn(LOGD_SHARING, "firewall: nft[%s]: command failed:%s%s%s%s%s%s%s", call_data->identifier, print_stdout || print_stderr ? "" : " unknown reason", NM_PRINT_FMT_QUOTED( print_stdout, " (stdout: \"", nm_utils_buf_utf8safe_escape_bytes(stdout_buf, NM_UTILS_STR_UTF8_SAFE_FLAG_ESCAPE_CTRL, &ss_stdout), "\")", ""), NM_PRINT_FMT_QUOTED( print_stderr, " (stderr: \"", nm_utils_buf_utf8safe_escape_bytes(stderr_buf, NM_UTILS_STR_UTF8_SAFE_FLAG_ESCAPE_CTRL, &ss_stderr), "\")", "")); } _fw_nft_call_data_free(call_data, g_steal_pointer(&error)); } static void _fw_nft_call_cancelled_cb(GCancellable *cancellable, gpointer user_data) { FwNftCallData *call_data = user_data; if (call_data->cancellable_id == 0) return; nm_log_dbg(LOGD_SHARING, "firewall: nft[%s]: operation cancelled", call_data->identifier); nm_clear_g_signal_handler(g_task_get_cancellable(call_data->task), &call_data->cancellable_id); nm_clear_g_cancellable(&call_data->intern_cancellable); } static gboolean _fw_nft_call_timeout_cb(gpointer user_data) { FwNftCallData *call_data = user_data; nm_clear_g_source_inst(&call_data->timeout_source); nm_log_dbg(LOGD_SHARING, "firewall: nft[%s]: cancel operation after timeout", call_data->identifier); nm_clear_g_cancellable(&call_data->intern_cancellable); return G_SOURCE_CONTINUE; } static void _fw_nft_call(GBytes *stdin_buf, GCancellable *cancellable, GAsyncReadyCallback callback, gpointer callback_user_data) { gs_unref_object GSubprocessLauncher *subprocess_launcher = NULL; gs_free_error GError *error = NULL; FwNftCallData *call_data; call_data = g_slice_new(FwNftCallData); *call_data = (FwNftCallData){ .task = nm_g_task_new(NULL, cancellable, _fw_nft_call, callback, callback_user_data), .subprocess = NULL, .timeout_source = NULL, }; if (cancellable) { call_data->cancellable_id = g_cancellable_connect(cancellable, G_CALLBACK(_fw_nft_call_cancelled_cb), call_data, NULL); if (call_data->cancellable_id == 0) { nm_log_dbg(LOGD_SHARING, "firewall: nft: already cancelled"); nm_utils_error_set_cancelled(&error, FALSE, NULL); _fw_nft_call_data_free(call_data, g_steal_pointer(&error)); return; } } subprocess_launcher = g_subprocess_launcher_new(G_SUBPROCESS_FLAGS_STDIN_PIPE | G_SUBPROCESS_FLAGS_STDOUT_PIPE | G_SUBPROCESS_FLAGS_STDERR_PIPE); g_subprocess_launcher_set_environ(subprocess_launcher, NM_STRV_EMPTY()); call_data->subprocess = g_subprocess_launcher_spawnv(subprocess_launcher, NM_MAKE_STRV(NFT_PATH, "-f", "-"), &error); if (!call_data->subprocess) { nm_log_dbg(LOGD_SHARING, "firewall: nft: spawning nft failed: %s", error->message); _fw_nft_call_data_free(call_data, g_steal_pointer(&error)); return; } call_data->identifier = g_strdup(g_subprocess_get_identifier(call_data->subprocess)); nm_log_dbg(LOGD_SHARING, "firewall: nft[%s]: communicate with nft", call_data->identifier); nm_shutdown_wait_obj_register_object(call_data->task, "nft-call"); call_data->intern_cancellable = g_cancellable_new(), g_subprocess_communicate_async(call_data->subprocess, stdin_buf, call_data->intern_cancellable, _fw_nft_call_communicate_cb, call_data); call_data->timeout_source = nm_g_source_attach(nm_g_timeout_source_new((NM_SHUTDOWN_TIMEOUT_1500_MSEC * 2) / 3, G_PRIORITY_DEFAULT, _fw_nft_call_timeout_cb, call_data, NULL), g_task_get_context(call_data->task)); } static gboolean _fw_nft_call_finish(GAsyncResult *result, GError **error) { g_return_val_if_fail(nm_g_task_is_valid(result, NULL, _fw_nft_call), FALSE); return g_task_propagate_boolean(G_TASK(result), error); } /*****************************************************************************/ typedef struct { GMainLoop *loop; GError **error; gboolean success; } FwNftCallSyncData; static void _fw_nft_call_sync_done(GObject *source, GAsyncResult *result, gpointer user_data) { FwNftCallSyncData *data = user_data; data->success = _fw_nft_call_finish(result, data->error); g_main_loop_quit(data->loop); } static gboolean _fw_nft_call_sync(GBytes *stdin_buf, GError **error) { nm_auto_pop_and_unref_gmaincontext GMainContext *main_context = nm_g_main_context_push_thread_default(g_main_context_new()); nm_auto_unref_gmainloop GMainLoop *main_loop = g_main_loop_new(main_context, FALSE); FwNftCallSyncData data = (FwNftCallSyncData){ .loop = main_loop, .error = error, }; _fw_nft_call(stdin_buf, NULL, _fw_nft_call_sync_done, &data); g_main_loop_run(main_loop); return data.success; } /*****************************************************************************/ static void _fw_nft_set(gboolean add, const char *ip_iface, in_addr_t addr, guint8 plen) { nm_auto_str_buf NMStrBuf strbuf = NM_STR_BUF_INIT(NM_UTILS_GET_NEXT_REALLOC_SIZE_1000, FALSE); gs_unref_bytes GBytes *stdin_buf = NULL; gs_free char *table_name = NULL; gs_free char *ss1 = NULL; char str_subnet[_SHARE_IPTABLES_SUBNET_TO_STR_LEN]; table_name = _share_iptables_get_name(FALSE, "nm-shared", ip_iface); _share_iptables_subnet_to_str(str_subnet, addr, plen); #define _append(p_strbuf, fmt, ...) nm_str_buf_append_printf((p_strbuf), "" fmt "\n", ##__VA_ARGS__) _append(&strbuf, "add table ip %s", table_name); _append(&strbuf, "%s table ip %s", add ? "flush" : "delete", table_name); if (add) { _append(&strbuf, "add chain ip %s nat_postrouting {" " type nat hook postrouting priority 100; policy accept; " "};", table_name); _append(&strbuf, "add rule ip %s nat_postrouting ip saddr %s ip daddr != %s masquerade;", table_name, str_subnet, str_subnet); /* This filter_input chain serves no real purpose, because "accept" only stops * evaluation of the current rule. It cannot fully accept the packet. Since * this chain has no other rules, it is useless in this form. */ /* _append(&strbuf, "add chain ip %s filter_input {" " type filter hook input priority 0; policy accept; " "};", table_name); _append(&strbuf, "add rule ip %s filter_input tcp dport { 67, 53 } accept;", table_name); _append(&strbuf, "add rule ip %s filter_input udp dport { 67, 53 } accept;", table_name); */ _append(&strbuf, "add chain ip %s filter_forward {" " type filter hook forward priority 0; policy accept; " "};", table_name); _append(&strbuf, "add rule ip %s filter_forward ip daddr %s oifname \"%s\" " " ct state { established, related } accept;", table_name, str_subnet, ip_iface); _append(&strbuf, "add rule ip %s filter_forward ip saddr %s iifname \"%s\" accept;", table_name, str_subnet, ip_iface); _append(&strbuf, "add rule ip %s filter_forward iifname \"%s\" oifname \"%s\" accept;", table_name, ip_iface, ip_iface); _append(&strbuf, "add rule ip %s filter_forward iifname \"%s\" reject;", table_name, ip_iface); _append(&strbuf, "add rule ip %s filter_forward oifname \"%s\" reject;", table_name, ip_iface); } nm_log_trace(LOGD_SHARING, "firewall: nft command: [ %s ]", nm_utils_str_utf8safe_escape(nm_str_buf_get_str(&strbuf), NM_UTILS_STR_UTF8_SAFE_FLAG_ESCAPE_CTRL, &ss1)); stdin_buf = nm_str_buf_finalize_to_gbytes(&strbuf); _fw_nft_call_sync(stdin_buf, NULL); } /*****************************************************************************/ struct _NMFirewallConfig { char *ip_iface; in_addr_t addr; guint8 plen; }; NMFirewallConfig * nm_firewall_config_new(const char *ip_iface, in_addr_t addr, guint8 plen) { NMFirewallConfig *self; nm_assert(ip_iface); nm_assert(addr != 0u); nm_assert(plen <= 32); self = g_slice_new(NMFirewallConfig); *self = (NMFirewallConfig){ .ip_iface = g_strdup(ip_iface), .addr = addr, .plen = plen, }; return self; } void nm_firewall_config_free(NMFirewallConfig *self) { if (!self) return; g_free(self->ip_iface); nm_g_slice_free(self); } void nm_firewall_config_apply(NMFirewallConfig *self, gboolean shared) { switch (nm_firewall_utils_get_backend()) { case NM_FIREWALL_BACKEND_IPTABLES: _share_iptables_set_masquerade(shared, self->ip_iface, self->addr, self->plen); _share_iptables_set_shared(shared, self->ip_iface, self->addr, self->plen); break; case NM_FIREWALL_BACKEND_NFTABLES: _fw_nft_set(shared, self->ip_iface, self->addr, self->plen); break; case NM_FIREWALL_BACKEND_NONE: break; default: nm_assert_not_reached(); break; } } /*****************************************************************************/ static NMFirewallBackend _firewall_backend_detect(void) { if (g_file_test(NFT_PATH, G_FILE_TEST_IS_EXECUTABLE)) return NM_FIREWALL_BACKEND_NFTABLES; if (g_file_test(IPTABLES_PATH, G_FILE_TEST_IS_EXECUTABLE)) return NM_FIREWALL_BACKEND_IPTABLES; return NM_FIREWALL_BACKEND_NFTABLES; } NMFirewallBackend nm_firewall_utils_get_backend(void) { static int backend = NM_FIREWALL_BACKEND_UNKNOWN; int b; again: b = g_atomic_int_get(&backend); if (b == NM_FIREWALL_BACKEND_UNKNOWN) { gs_free char *conf_value = NULL; gboolean detect; int i; conf_value = nm_config_data_get_value(NM_CONFIG_GET_DATA_ORIG, NM_CONFIG_KEYFILE_GROUP_MAIN, NM_CONFIG_KEYFILE_KEY_MAIN_FIREWALL_BACKEND, NM_CONFIG_GET_VALUE_STRIP | NM_CONFIG_GET_VALUE_NO_EMPTY); if (conf_value) { for (i = 0; i < (int) G_N_ELEMENTS(FirewallBackends); i++) { if (!g_ascii_strcasecmp(conf_value, FirewallBackends[i].name)) { b = (i + 1); break; } } } detect = (b == NM_FIREWALL_BACKEND_UNKNOWN); if (detect) b = _firewall_backend_detect(); nm_assert(NM_IN_SET(b, NM_FIREWALL_BACKEND_NONE, NM_FIREWALL_BACKEND_IPTABLES, NM_FIREWALL_BACKEND_NFTABLES)); if (!g_atomic_int_compare_and_exchange(&backend, NM_FIREWALL_BACKEND_UNKNOWN, b)) goto again; nm_log_dbg(LOGD_SHARING, "firewall: use %s backend%s%s%s%s%s%s%s", FirewallBackends[b - 1].name, NM_PRINT_FMT_QUOTED(FirewallBackends[b - 1].path, " (", FirewallBackends[b - 1].path, ")", ""), detect ? " (detected)" : "", NM_PRINT_FMT_QUOTED(detect && conf_value, " (invalid setting \"", conf_value, "\")", "")); } nm_assert(NM_IN_SET(b, NM_FIREWALL_BACKEND_NONE, NM_FIREWALL_BACKEND_IPTABLES, NM_FIREWALL_BACKEND_NFTABLES)); return b; }