2 * firewall3 - 3rd OpenWrt UCI firewall implementation
4 * Copyright (C) 2013 Jo-Philipp Wich <jo@mein.io>
6 * Permission to use, copy, modify, and/or distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
22 #define C(f, tbl, def, fmt) \
23 { FW3_FAMILY_##f, FW3_TABLE_##tbl, FW3_FLAG_##def, fmt }
25 static const struct fw3_chain_spec default_chains[] = {
26 C(ANY, FILTER, UNSPEC, "reject"),
27 C(ANY, FILTER, CUSTOM_CHAINS, "input_rule"),
28 C(ANY, FILTER, CUSTOM_CHAINS, "output_rule"),
29 C(ANY, FILTER, CUSTOM_CHAINS, "forwarding_rule"),
30 C(ANY, FILTER, SYN_FLOOD, "syn_flood"),
32 C(V4, NAT, CUSTOM_CHAINS, "prerouting_rule"),
33 C(V4, NAT, CUSTOM_CHAINS, "postrouting_rule"),
38 const struct fw3_option fw3_flag_opts[] = {
39 FW3_OPT("input", target, defaults, policy_input),
40 FW3_OPT("forward", target, defaults, policy_forward),
41 FW3_OPT("output", target, defaults, policy_output),
43 FW3_OPT("drop_invalid", bool, defaults, drop_invalid),
45 FW3_OPT("syn_flood", bool, defaults, syn_flood),
46 FW3_OPT("synflood_protect", bool, defaults, syn_flood),
47 FW3_OPT("synflood_rate", limit, defaults, syn_flood_rate),
48 FW3_OPT("synflood_burst", int, defaults, syn_flood_rate.burst),
50 FW3_OPT("tcp_syncookies", bool, defaults, tcp_syncookies),
51 FW3_OPT("tcp_ecn", int, defaults, tcp_ecn),
52 FW3_OPT("tcp_window_scaling", bool, defaults, tcp_window_scaling),
54 FW3_OPT("accept_redirects", bool, defaults, accept_redirects),
55 FW3_OPT("accept_source_route", bool, defaults, accept_source_route),
57 FW3_OPT("auto_helper", bool, defaults, auto_helper),
58 FW3_OPT("custom_chains", bool, defaults, custom_chains),
59 FW3_OPT("disable_ipv6", bool, defaults, disable_ipv6),
61 FW3_OPT("__flags_v4", int, defaults, flags[0]),
62 FW3_OPT("__flags_v6", int, defaults, flags[1]),
69 check_policy(struct uci_element *e, enum fw3_flag *pol, const char *name)
71 if (*pol == FW3_FLAG_UNSPEC)
73 warn_elem(e, "has no %s policy specified, defaulting to DROP", name);
76 else if (*pol > FW3_FLAG_DROP)
78 warn_elem(e, "has invalid %s policy, defaulting to DROP", name);
84 fw3_load_defaults(struct fw3_state *state, struct uci_package *p)
86 struct uci_section *s;
87 struct uci_element *e;
88 struct fw3_defaults *defs = &state->defaults;
92 defs->syn_flood_rate.rate = 25;
93 defs->syn_flood_rate.burst = 50;
94 defs->tcp_syncookies = true;
95 defs->tcp_window_scaling = true;
96 defs->custom_chains = true;
97 defs->auto_helper = true;
99 uci_foreach_element(&p->sections, e)
101 s = uci_to_section(e);
103 if (strcmp(s->type, "defaults"))
108 warn_elem(e, "ignoring duplicate section");
112 if(!fw3_parse_options(&state->defaults, fw3_flag_opts, s))
113 warn_elem(e, "has invalid options");
115 check_policy(e, &defs->policy_input, "input");
116 check_policy(e, &defs->policy_output, "output");
117 check_policy(e, &defs->policy_forward, "forward");
122 fw3_print_default_chains(struct fw3_ipt_handle *handle, struct fw3_state *state,
125 struct fw3_defaults *defs = &state->defaults;
126 const struct fw3_chain_spec *c;
129 ((t == FW3_FLAG_REJECT) ? FW3_FLAG_DROP : t)
131 if (handle->family == FW3_FAMILY_V6 && defs->disable_ipv6)
134 if (handle->table == FW3_TABLE_FILTER)
136 fw3_ipt_set_policy(handle, "INPUT", policy(defs->policy_input));
137 fw3_ipt_set_policy(handle, "OUTPUT", policy(defs->policy_output));
138 fw3_ipt_set_policy(handle, "FORWARD", policy(defs->policy_forward));
141 if (defs->custom_chains)
142 set(defs->flags, handle->family, FW3_FLAG_CUSTOM_CHAINS);
145 set(defs->flags, handle->family, FW3_FLAG_SYN_FLOOD);
147 for (c = default_chains; c->format; c++)
149 /* don't touch user chains on selective stop */
150 if (reload && c->flag == FW3_FLAG_CUSTOM_CHAINS)
153 if (!fw3_is_family(c, handle->family))
156 if (c->table != handle->table)
160 !fw3_hasbit(defs->flags[handle->family == FW3_FAMILY_V6], c->flag))
163 fw3_ipt_create_chain(handle, c->format);
166 set(defs->flags, handle->family, handle->table);
170 fw3_print_default_head_rules(struct fw3_ipt_handle *handle,
171 struct fw3_state *state, bool reload)
174 struct fw3_defaults *defs = &state->defaults;
175 struct fw3_device lodev = { .set = true };
176 struct fw3_protocol tcp = { .protocol = 6 };
177 struct fw3_ipt_rule *r;
179 const char *chains[] = {
182 "FORWARD", "forwarding",
185 switch (handle->table)
187 case FW3_TABLE_FILTER:
189 sprintf(lodev.name, "lo");
191 r = fw3_ipt_rule_create(handle, NULL, &lodev, NULL, NULL, NULL);
192 fw3_ipt_rule_target(r, "ACCEPT");
193 fw3_ipt_rule_append(r, "INPUT");
195 r = fw3_ipt_rule_create(handle, NULL, NULL, &lodev, NULL, NULL);
196 fw3_ipt_rule_target(r, "ACCEPT");
197 fw3_ipt_rule_append(r, "OUTPUT");
199 if (defs->custom_chains)
201 for (i = 0; i < ARRAY_SIZE(chains); i += 2)
203 r = fw3_ipt_rule_new(handle);
204 fw3_ipt_rule_comment(r, "user chain for %s", chains[i+1]);
205 fw3_ipt_rule_target(r, "%s_rule", chains[i+1]);
206 fw3_ipt_rule_append(r, chains[i]);
210 for (i = 0; i < ARRAY_SIZE(chains); i += 2)
212 r = fw3_ipt_rule_new(handle);
213 fw3_ipt_rule_extra(r, "-m conntrack --ctstate RELATED,ESTABLISHED");
214 fw3_ipt_rule_target(r, "ACCEPT");
215 fw3_ipt_rule_append(r, chains[i]);
217 if (defs->drop_invalid)
219 r = fw3_ipt_rule_new(handle);
220 fw3_ipt_rule_extra(r, "-m conntrack --ctstate INVALID");
221 fw3_ipt_rule_target(r, "DROP");
222 fw3_ipt_rule_append(r, chains[i]);
228 r = fw3_ipt_rule_create(handle, &tcp, NULL, NULL, NULL, NULL);
229 fw3_ipt_rule_extra(r, "--syn");
230 fw3_ipt_rule_limit(r, &defs->syn_flood_rate);
231 fw3_ipt_rule_target(r, "RETURN");
232 fw3_ipt_rule_append(r, "syn_flood");
234 r = fw3_ipt_rule_new(handle);
235 fw3_ipt_rule_target(r, "DROP");
236 fw3_ipt_rule_append(r, "syn_flood");
238 r = fw3_ipt_rule_create(handle, &tcp, NULL, NULL, NULL, NULL);
239 fw3_ipt_rule_extra(r, "--syn");
240 fw3_ipt_rule_target(r, "syn_flood");
241 fw3_ipt_rule_append(r, "INPUT");
244 r = fw3_ipt_rule_create(handle, &tcp, NULL, NULL, NULL, NULL);
245 fw3_ipt_rule_target(r, "REJECT");
246 fw3_ipt_rule_addarg(r, false, "--reject-with", "tcp-reset");
247 fw3_ipt_rule_append(r, "reject");
249 r = fw3_ipt_rule_new(handle);
250 fw3_ipt_rule_target(r, "REJECT");
251 fw3_ipt_rule_addarg(r, false, "--reject-with", "port-unreach");
252 fw3_ipt_rule_append(r, "reject");
257 if (defs->custom_chains)
259 r = fw3_ipt_rule_new(handle);
260 fw3_ipt_rule_comment(r, "user chain for prerouting");
261 fw3_ipt_rule_target(r, "prerouting_rule");
262 fw3_ipt_rule_append(r, "PREROUTING");
264 r = fw3_ipt_rule_new(handle);
265 fw3_ipt_rule_comment(r, "user chain for postrouting");
266 fw3_ipt_rule_target(r, "postrouting_rule");
267 fw3_ipt_rule_append(r, "POSTROUTING");
277 fw3_print_default_tail_rules(struct fw3_ipt_handle *handle,
278 struct fw3_state *state, bool reload)
280 struct fw3_defaults *defs = &state->defaults;
281 struct fw3_ipt_rule *r;
283 if (handle->table != FW3_TABLE_FILTER)
286 if (defs->policy_input == FW3_FLAG_REJECT)
288 r = fw3_ipt_rule_new(handle);
293 fw3_ipt_rule_target(r, "reject");
294 fw3_ipt_rule_append(r, "INPUT");
297 if (defs->policy_output == FW3_FLAG_REJECT)
299 r = fw3_ipt_rule_new(handle);
304 fw3_ipt_rule_target(r, "reject");
305 fw3_ipt_rule_append(r, "OUTPUT");
308 if (defs->policy_forward == FW3_FLAG_REJECT)
310 r = fw3_ipt_rule_new(handle);
315 fw3_ipt_rule_target(r, "reject");
316 fw3_ipt_rule_append(r, "FORWARD");
321 set_default(const char *name, int set)
324 char path[sizeof("/proc/sys/net/ipv4/tcp_window_scaling\0")];
326 snprintf(path, sizeof(path), "/proc/sys/net/ipv4/tcp_%s", name);
328 info(" * Set tcp_%s to %s", name, set ? "on" : "off", name);
330 if (!(f = fopen(path, "w")))
332 info(" ! Unable to write value: %s", strerror(errno));
336 fprintf(f, "%u\n", set);
341 fw3_set_defaults(struct fw3_state *state)
343 set_default("ecn", state->defaults.tcp_ecn);
344 set_default("syncookies", state->defaults.tcp_syncookies);
345 set_default("window_scaling", state->defaults.tcp_window_scaling);
349 fw3_flush_rules(struct fw3_ipt_handle *handle, struct fw3_state *state,
352 enum fw3_flag policy = reload ? FW3_FLAG_DROP : FW3_FLAG_ACCEPT;
353 struct fw3_defaults *defs = &state->defaults;
354 const struct fw3_chain_spec *c;
356 if (!has(defs->flags, handle->family, handle->table))
359 if (handle->table == FW3_TABLE_FILTER)
361 fw3_ipt_set_policy(handle, "INPUT", policy);
362 fw3_ipt_set_policy(handle, "OUTPUT", policy);
363 fw3_ipt_set_policy(handle, "FORWARD", policy);
366 fw3_ipt_delete_id_rules(handle, "INPUT");
367 fw3_ipt_delete_id_rules(handle, "OUTPUT");
368 fw3_ipt_delete_id_rules(handle, "FORWARD");
369 fw3_ipt_delete_id_rules(handle, "PREROUTING");
370 fw3_ipt_delete_id_rules(handle, "POSTROUTING");
372 for (c = default_chains; c->format; c++)
374 /* don't touch user chains on selective stop */
375 if (reload && c->flag == FW3_FLAG_CUSTOM_CHAINS)
378 if (!fw3_is_family(c, handle->family))
381 if (c->table != handle->table)
384 if (c->flag && !has(defs->flags, handle->family, c->flag))
387 fw3_ipt_flush_chain(handle, c->format);
389 /* keep certain basic chains that do not depend on any settings to
390 avoid purging unrelated user rules pointing to them */
391 if (reload && !c->flag)
394 fw3_ipt_delete_chain(handle, c->format);
397 del(defs->flags, handle->family, handle->table);
401 fw3_flush_all(struct fw3_ipt_handle *handle)
403 if (handle->table == FW3_TABLE_FILTER)
405 fw3_ipt_set_policy(handle, "INPUT", FW3_FLAG_ACCEPT);
406 fw3_ipt_set_policy(handle, "OUTPUT", FW3_FLAG_ACCEPT);
407 fw3_ipt_set_policy(handle, "FORWARD", FW3_FLAG_ACCEPT);
410 fw3_ipt_flush(handle);