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76917807 LP |
1 | /*** |
2 | This file is part of systemd. | |
3 | ||
4 | Copyright 2015 Lennart Poettering | |
5 | ||
6 | systemd is free software; you can redistribute it and/or modify it | |
7 | under the terms of the GNU Lesser General Public License as published by | |
8 | the Free Software Foundation; either version 2.1 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | systemd is distributed in the hope that it will be useful, but | |
12 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Lesser General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Lesser General Public License | |
17 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
18 | ***/ | |
19 | ||
2dc95d98 ZJS |
20 | /* Temporary work-around for broken glibc vs. linux kernel header definitions |
21 | * This is already fixed upstream, remove this when distributions have updated. | |
22 | */ | |
08ce521f LP |
23 | #define _NET_IF_H 1 |
24 | ||
a8fbdf54 | 25 | #include <alloca.h> |
76917807 | 26 | #include <arpa/inet.h> |
a8fbdf54 TA |
27 | #include <endian.h> |
28 | #include <errno.h> | |
a8fbdf54 TA |
29 | #include <stddef.h> |
30 | #include <string.h> | |
31 | #include <sys/socket.h> | |
08ce521f | 32 | #include <net/if.h> |
08ce521f | 33 | #ifndef IFNAMSIZ |
6f270e6b | 34 | #define IFNAMSIZ 16 |
08ce521f | 35 | #endif |
6f270e6b | 36 | #include <linux/if.h> |
76917807 LP |
37 | #include <linux/netfilter_ipv4/ip_tables.h> |
38 | #include <linux/netfilter/nf_nat.h> | |
39 | #include <linux/netfilter/xt_addrtype.h> | |
40 | #include <libiptc/libiptc.h> | |
41 | ||
b5efdb8a | 42 | #include "alloc-util.h" |
12c2884c | 43 | #include "firewall-util.h" |
a8fbdf54 TA |
44 | #include "in-addr-util.h" |
45 | #include "macro.h" | |
d31645ad | 46 | #include "socket-util.h" |
76917807 LP |
47 | |
48 | DEFINE_TRIVIAL_CLEANUP_FUNC(struct xtc_handle*, iptc_free); | |
49 | ||
50 | static int entry_fill_basics( | |
51 | struct ipt_entry *entry, | |
52 | int protocol, | |
53 | const char *in_interface, | |
54 | const union in_addr_union *source, | |
55 | unsigned source_prefixlen, | |
56 | const char *out_interface, | |
57 | const union in_addr_union *destination, | |
58 | unsigned destination_prefixlen) { | |
59 | ||
60 | assert(entry); | |
61 | ||
d31645ad | 62 | if (out_interface && !ifname_valid(out_interface)) |
76917807 | 63 | return -EINVAL; |
d31645ad | 64 | if (in_interface && !ifname_valid(in_interface)) |
76917807 LP |
65 | return -EINVAL; |
66 | ||
67 | entry->ip.proto = protocol; | |
68 | ||
69 | if (in_interface) { | |
70 | strcpy(entry->ip.iniface, in_interface); | |
71 | memset(entry->ip.iniface_mask, 0xFF, strlen(in_interface)+1); | |
72 | } | |
73 | if (source) { | |
74 | entry->ip.src = source->in; | |
5a941f5f | 75 | in4_addr_prefixlen_to_netmask(&entry->ip.smsk, source_prefixlen); |
76917807 LP |
76 | } |
77 | ||
78 | if (out_interface) { | |
f2850127 ZJS |
79 | size_t l = strlen(out_interface); |
80 | assert(l < sizeof entry->ip.outiface && l < sizeof entry->ip.outiface_mask); | |
81 | ||
76917807 | 82 | strcpy(entry->ip.outiface, out_interface); |
f2850127 | 83 | memset(entry->ip.outiface_mask, 0xFF, l + 1); |
76917807 LP |
84 | } |
85 | if (destination) { | |
86 | entry->ip.dst = destination->in; | |
5a941f5f | 87 | in4_addr_prefixlen_to_netmask(&entry->ip.dmsk, destination_prefixlen); |
76917807 LP |
88 | } |
89 | ||
90 | return 0; | |
91 | } | |
92 | ||
93 | int fw_add_masquerade( | |
94 | bool add, | |
95 | int af, | |
96 | int protocol, | |
97 | const union in_addr_union *source, | |
98 | unsigned source_prefixlen, | |
99 | const char *out_interface, | |
100 | const union in_addr_union *destination, | |
101 | unsigned destination_prefixlen) { | |
102 | ||
103 | _cleanup_(iptc_freep) struct xtc_handle *h = NULL; | |
104 | struct ipt_entry *entry, *mask; | |
105 | struct ipt_entry_target *t; | |
106 | size_t sz; | |
107 | struct nf_nat_ipv4_multi_range_compat *mr; | |
108 | int r; | |
109 | ||
110 | if (af != AF_INET) | |
15411c0c | 111 | return -EOPNOTSUPP; |
76917807 | 112 | |
4c701096 | 113 | if (!IN_SET(protocol, 0, IPPROTO_TCP, IPPROTO_UDP)) |
15411c0c | 114 | return -EOPNOTSUPP; |
76917807 LP |
115 | |
116 | h = iptc_init("nat"); | |
117 | if (!h) | |
118 | return -errno; | |
119 | ||
120 | sz = XT_ALIGN(sizeof(struct ipt_entry)) + | |
121 | XT_ALIGN(sizeof(struct ipt_entry_target)) + | |
122 | XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)); | |
123 | ||
124 | /* Put together the entry we want to add or remove */ | |
125 | entry = alloca0(sz); | |
126 | entry->next_offset = sz; | |
127 | entry->target_offset = XT_ALIGN(sizeof(struct ipt_entry)); | |
128 | r = entry_fill_basics(entry, protocol, NULL, source, source_prefixlen, out_interface, destination, destination_prefixlen); | |
129 | if (r < 0) | |
130 | return r; | |
131 | ||
132 | /* Fill in target part */ | |
133 | t = ipt_get_target(entry); | |
134 | t->u.target_size = | |
135 | XT_ALIGN(sizeof(struct ipt_entry_target)) + | |
136 | XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)); | |
137 | strncpy(t->u.user.name, "MASQUERADE", sizeof(t->u.user.name)); | |
138 | mr = (struct nf_nat_ipv4_multi_range_compat*) t->data; | |
139 | mr->rangesize = 1; | |
140 | ||
141 | /* Create a search mask entry */ | |
142 | mask = alloca(sz); | |
143 | memset(mask, 0xFF, sz); | |
144 | ||
145 | if (add) { | |
146 | if (iptc_check_entry("POSTROUTING", entry, (unsigned char*) mask, h)) | |
147 | return 0; | |
148 | if (errno != ENOENT) /* if other error than not existing yet, fail */ | |
149 | return -errno; | |
150 | ||
151 | if (!iptc_insert_entry("POSTROUTING", entry, 0, h)) | |
152 | return -errno; | |
153 | } else { | |
154 | if (!iptc_delete_entry("POSTROUTING", entry, (unsigned char*) mask, h)) { | |
155 | if (errno == ENOENT) /* if it's already gone, all is good! */ | |
156 | return 0; | |
157 | ||
158 | return -errno; | |
159 | } | |
160 | } | |
161 | ||
162 | if (!iptc_commit(h)) | |
163 | return -errno; | |
164 | ||
165 | return 0; | |
166 | } | |
167 | ||
168 | int fw_add_local_dnat( | |
169 | bool add, | |
170 | int af, | |
171 | int protocol, | |
172 | const char *in_interface, | |
173 | const union in_addr_union *source, | |
174 | unsigned source_prefixlen, | |
175 | const union in_addr_union *destination, | |
176 | unsigned destination_prefixlen, | |
177 | uint16_t local_port, | |
178 | const union in_addr_union *remote, | |
179 | uint16_t remote_port, | |
180 | const union in_addr_union *previous_remote) { | |
181 | ||
182 | ||
183 | _cleanup_(iptc_freep) struct xtc_handle *h = NULL; | |
184 | struct ipt_entry *entry, *mask; | |
185 | struct ipt_entry_target *t; | |
186 | struct ipt_entry_match *m; | |
187 | struct xt_addrtype_info_v1 *at; | |
188 | struct nf_nat_ipv4_multi_range_compat *mr; | |
189 | size_t sz, msz; | |
190 | int r; | |
191 | ||
192 | assert(add || !previous_remote); | |
193 | ||
194 | if (af != AF_INET) | |
15411c0c | 195 | return -EOPNOTSUPP; |
76917807 | 196 | |
4c701096 | 197 | if (!IN_SET(protocol, IPPROTO_TCP, IPPROTO_UDP)) |
15411c0c | 198 | return -EOPNOTSUPP; |
76917807 LP |
199 | |
200 | if (local_port <= 0) | |
201 | return -EINVAL; | |
202 | ||
203 | if (remote_port <= 0) | |
204 | return -EINVAL; | |
205 | ||
206 | h = iptc_init("nat"); | |
207 | if (!h) | |
208 | return -errno; | |
209 | ||
210 | sz = XT_ALIGN(sizeof(struct ipt_entry)) + | |
211 | XT_ALIGN(sizeof(struct ipt_entry_match)) + | |
212 | XT_ALIGN(sizeof(struct xt_addrtype_info_v1)) + | |
213 | XT_ALIGN(sizeof(struct ipt_entry_target)) + | |
214 | XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)); | |
215 | ||
216 | if (protocol == IPPROTO_TCP) | |
217 | msz = XT_ALIGN(sizeof(struct ipt_entry_match)) + | |
218 | XT_ALIGN(sizeof(struct xt_tcp)); | |
219 | else | |
220 | msz = XT_ALIGN(sizeof(struct ipt_entry_match)) + | |
221 | XT_ALIGN(sizeof(struct xt_udp)); | |
222 | ||
223 | sz += msz; | |
224 | ||
225 | /* Fill in basic part */ | |
226 | entry = alloca0(sz); | |
227 | entry->next_offset = sz; | |
228 | entry->target_offset = | |
229 | XT_ALIGN(sizeof(struct ipt_entry)) + | |
230 | XT_ALIGN(sizeof(struct ipt_entry_match)) + | |
231 | XT_ALIGN(sizeof(struct xt_addrtype_info_v1)) + | |
232 | msz; | |
233 | r = entry_fill_basics(entry, protocol, in_interface, source, source_prefixlen, NULL, destination, destination_prefixlen); | |
234 | if (r < 0) | |
235 | return r; | |
236 | ||
237 | /* Fill in first match */ | |
238 | m = (struct ipt_entry_match*) ((uint8_t*) entry + XT_ALIGN(sizeof(struct ipt_entry))); | |
239 | m->u.match_size = msz; | |
240 | if (protocol == IPPROTO_TCP) { | |
241 | struct xt_tcp *tcp; | |
242 | ||
243 | strncpy(m->u.user.name, "tcp", sizeof(m->u.user.name)); | |
244 | tcp = (struct xt_tcp*) m->data; | |
245 | tcp->dpts[0] = tcp->dpts[1] = local_port; | |
246 | tcp->spts[0] = 0; | |
247 | tcp->spts[1] = 0xFFFF; | |
248 | ||
249 | } else { | |
250 | struct xt_udp *udp; | |
251 | ||
252 | strncpy(m->u.user.name, "udp", sizeof(m->u.user.name)); | |
253 | udp = (struct xt_udp*) m->data; | |
254 | udp->dpts[0] = udp->dpts[1] = local_port; | |
255 | udp->spts[0] = 0; | |
256 | udp->spts[1] = 0xFFFF; | |
257 | } | |
258 | ||
259 | /* Fill in second match */ | |
260 | m = (struct ipt_entry_match*) ((uint8_t*) entry + XT_ALIGN(sizeof(struct ipt_entry)) + msz); | |
261 | m->u.match_size = | |
262 | XT_ALIGN(sizeof(struct ipt_entry_match)) + | |
263 | XT_ALIGN(sizeof(struct xt_addrtype_info_v1)); | |
264 | strncpy(m->u.user.name, "addrtype", sizeof(m->u.user.name)); | |
265 | m->u.user.revision = 1; | |
266 | at = (struct xt_addrtype_info_v1*) m->data; | |
267 | at->dest = XT_ADDRTYPE_LOCAL; | |
268 | ||
269 | /* Fill in target part */ | |
270 | t = ipt_get_target(entry); | |
271 | t->u.target_size = | |
272 | XT_ALIGN(sizeof(struct ipt_entry_target)) + | |
273 | XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)); | |
274 | strncpy(t->u.user.name, "DNAT", sizeof(t->u.user.name)); | |
275 | mr = (struct nf_nat_ipv4_multi_range_compat*) t->data; | |
276 | mr->rangesize = 1; | |
277 | mr->range[0].flags = NF_NAT_RANGE_PROTO_SPECIFIED|NF_NAT_RANGE_MAP_IPS; | |
278 | mr->range[0].min_ip = mr->range[0].max_ip = remote->in.s_addr; | |
279 | if (protocol == IPPROTO_TCP) | |
280 | mr->range[0].min.tcp.port = mr->range[0].max.tcp.port = htons(remote_port); | |
281 | else | |
282 | mr->range[0].min.udp.port = mr->range[0].max.udp.port = htons(remote_port); | |
283 | ||
284 | mask = alloca0(sz); | |
285 | memset(mask, 0xFF, sz); | |
286 | ||
287 | if (add) { | |
288 | /* Add the PREROUTING rule, if it is missing so far */ | |
289 | if (!iptc_check_entry("PREROUTING", entry, (unsigned char*) mask, h)) { | |
290 | if (errno != ENOENT) | |
291 | return -EINVAL; | |
292 | ||
293 | if (!iptc_insert_entry("PREROUTING", entry, 0, h)) | |
294 | return -errno; | |
295 | } | |
296 | ||
297 | /* If a previous remote is set, remove its entry */ | |
298 | if (previous_remote && previous_remote->in.s_addr != remote->in.s_addr) { | |
299 | mr->range[0].min_ip = mr->range[0].max_ip = previous_remote->in.s_addr; | |
300 | ||
301 | if (!iptc_delete_entry("PREROUTING", entry, (unsigned char*) mask, h)) { | |
302 | if (errno != ENOENT) | |
303 | return -errno; | |
304 | } | |
305 | ||
306 | mr->range[0].min_ip = mr->range[0].max_ip = remote->in.s_addr; | |
307 | } | |
308 | ||
309 | /* Add the OUTPUT rule, if it is missing so far */ | |
310 | if (!in_interface) { | |
311 | ||
312 | /* Don't apply onto loopback addresses */ | |
313 | if (!destination) { | |
314 | entry->ip.dst.s_addr = htobe32(0x7F000000); | |
315 | entry->ip.dmsk.s_addr = htobe32(0xFF000000); | |
316 | entry->ip.invflags = IPT_INV_DSTIP; | |
317 | } | |
318 | ||
319 | if (!iptc_check_entry("OUTPUT", entry, (unsigned char*) mask, h)) { | |
320 | if (errno != ENOENT) | |
321 | return -errno; | |
322 | ||
323 | if (!iptc_insert_entry("OUTPUT", entry, 0, h)) | |
324 | return -errno; | |
325 | } | |
326 | ||
327 | /* If a previous remote is set, remove its entry */ | |
328 | if (previous_remote && previous_remote->in.s_addr != remote->in.s_addr) { | |
329 | mr->range[0].min_ip = mr->range[0].max_ip = previous_remote->in.s_addr; | |
330 | ||
331 | if (!iptc_delete_entry("OUTPUT", entry, (unsigned char*) mask, h)) { | |
332 | if (errno != ENOENT) | |
333 | return -errno; | |
334 | } | |
335 | } | |
336 | } | |
337 | } else { | |
338 | if (!iptc_delete_entry("PREROUTING", entry, (unsigned char*) mask, h)) { | |
339 | if (errno != ENOENT) | |
340 | return -errno; | |
341 | } | |
342 | ||
343 | if (!in_interface) { | |
344 | if (!destination) { | |
345 | entry->ip.dst.s_addr = htobe32(0x7F000000); | |
346 | entry->ip.dmsk.s_addr = htobe32(0xFF000000); | |
347 | entry->ip.invflags = IPT_INV_DSTIP; | |
348 | } | |
349 | ||
350 | if (!iptc_delete_entry("OUTPUT", entry, (unsigned char*) mask, h)) { | |
351 | if (errno != ENOENT) | |
352 | return -errno; | |
353 | } | |
354 | } | |
355 | } | |
356 | ||
357 | if (!iptc_commit(h)) | |
358 | return -errno; | |
359 | ||
360 | return 0; | |
361 | } |