1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
6 *
7 * IPv4 Forwarding Information Base: policy rules.
8 *
9 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
10 * Thomas Graf <tgraf@suug.ch>
11 *
12 * Fixes:
13 * Rani Assaf : local_rule cannot be deleted
14 * Marc Boucher : routing by fwmark
15 */
16
17 #include <linux/types.h>
18 #include <linux/kernel.h>
19 #include <linux/netdevice.h>
20 #include <linux/netlink.h>
21 #include <linux/inetdevice.h>
22 #include <linux/init.h>
23 #include <linux/list.h>
24 #include <linux/rcupdate.h>
25 #include <linux/export.h>
26 #include <net/ip.h>
27 #include <net/route.h>
28 #include <net/tcp.h>
29 #include <net/ip_fib.h>
30 #include <net/nexthop.h>
31 #include <net/fib_rules.h>
32 #include <linux/indirect_call_wrapper.h>
33
34 struct fib4_rule {
35 struct fib_rule common;
36 u8 dst_len;
37 u8 src_len;
38 u8 tos;
39 __be32 src;
40 __be32 srcmask;
41 __be32 dst;
42 __be32 dstmask;
43 #ifdef CONFIG_IP_ROUTE_CLASSID
44 u32 tclassid;
45 #endif
46 };
47
fib4_rule_matchall(const struct fib_rule * rule)48 static bool fib4_rule_matchall(const struct fib_rule *rule)
49 {
50 struct fib4_rule *r = container_of(rule, struct fib4_rule, common);
51
52 if (r->dst_len || r->src_len || r->tos)
53 return false;
54 return fib_rule_matchall(rule);
55 }
56
fib4_rule_default(const struct fib_rule * rule)57 bool fib4_rule_default(const struct fib_rule *rule)
58 {
59 if (!fib4_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL ||
60 rule->l3mdev)
61 return false;
62 if (rule->table != RT_TABLE_LOCAL && rule->table != RT_TABLE_MAIN &&
63 rule->table != RT_TABLE_DEFAULT)
64 return false;
65 return true;
66 }
67 EXPORT_SYMBOL_GPL(fib4_rule_default);
68
fib4_rules_dump(struct net * net,struct notifier_block * nb,struct netlink_ext_ack * extack)69 int fib4_rules_dump(struct net *net, struct notifier_block *nb,
70 struct netlink_ext_ack *extack)
71 {
72 return fib_rules_dump(net, nb, AF_INET, extack);
73 }
74
fib4_rules_seq_read(struct net * net)75 unsigned int fib4_rules_seq_read(struct net *net)
76 {
77 return fib_rules_seq_read(net, AF_INET);
78 }
79
__fib_lookup(struct net * net,struct flowi4 * flp,struct fib_result * res,unsigned int flags)80 int __fib_lookup(struct net *net, struct flowi4 *flp,
81 struct fib_result *res, unsigned int flags)
82 {
83 struct fib_lookup_arg arg = {
84 .result = res,
85 .flags = flags,
86 };
87 int err;
88
89 /* update flow if oif or iif point to device enslaved to l3mdev */
90 l3mdev_update_flow(net, flowi4_to_flowi(flp));
91
92 err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);
93 #ifdef CONFIG_IP_ROUTE_CLASSID
94 if (arg.rule)
95 res->tclassid = ((struct fib4_rule *)arg.rule)->tclassid;
96 else
97 res->tclassid = 0;
98 #endif
99
100 if (err == -ESRCH)
101 err = -ENETUNREACH;
102
103 return err;
104 }
105 EXPORT_SYMBOL_GPL(__fib_lookup);
106
fib4_rule_action(struct fib_rule * rule,struct flowi * flp,int flags,struct fib_lookup_arg * arg)107 INDIRECT_CALLABLE_SCOPE int fib4_rule_action(struct fib_rule *rule,
108 struct flowi *flp, int flags,
109 struct fib_lookup_arg *arg)
110 {
111 int err = -EAGAIN;
112 struct fib_table *tbl;
113 u32 tb_id;
114
115 switch (rule->action) {
116 case FR_ACT_TO_TBL:
117 break;
118
119 case FR_ACT_UNREACHABLE:
120 return -ENETUNREACH;
121
122 case FR_ACT_PROHIBIT:
123 return -EACCES;
124
125 case FR_ACT_BLACKHOLE:
126 default:
127 return -EINVAL;
128 }
129
130 rcu_read_lock();
131
132 tb_id = fib_rule_get_table(rule, arg);
133 tbl = fib_get_table(rule->fr_net, tb_id);
134 if (tbl)
135 err = fib_table_lookup(tbl, &flp->u.ip4,
136 (struct fib_result *)arg->result,
137 arg->flags);
138
139 rcu_read_unlock();
140 return err;
141 }
142
fib4_rule_suppress(struct fib_rule * rule,struct fib_lookup_arg * arg)143 INDIRECT_CALLABLE_SCOPE bool fib4_rule_suppress(struct fib_rule *rule,
144 struct fib_lookup_arg *arg)
145 {
146 struct fib_result *result = (struct fib_result *) arg->result;
147 struct net_device *dev = NULL;
148
149 if (result->fi) {
150 struct fib_nh_common *nhc = fib_info_nhc(result->fi, 0);
151
152 dev = nhc->nhc_dev;
153 }
154
155 /* do not accept result if the route does
156 * not meet the required prefix length
157 */
158 if (result->prefixlen <= rule->suppress_prefixlen)
159 goto suppress_route;
160
161 /* do not accept result if the route uses a device
162 * belonging to a forbidden interface group
163 */
164 if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
165 goto suppress_route;
166
167 return false;
168
169 suppress_route:
170 if (!(arg->flags & FIB_LOOKUP_NOREF))
171 fib_info_put(result->fi);
172 return true;
173 }
174
fib4_rule_match(struct fib_rule * rule,struct flowi * fl,int flags)175 INDIRECT_CALLABLE_SCOPE int fib4_rule_match(struct fib_rule *rule,
176 struct flowi *fl, int flags)
177 {
178 struct fib4_rule *r = (struct fib4_rule *) rule;
179 struct flowi4 *fl4 = &fl->u.ip4;
180 __be32 daddr = fl4->daddr;
181 __be32 saddr = fl4->saddr;
182
183 if (((saddr ^ r->src) & r->srcmask) ||
184 ((daddr ^ r->dst) & r->dstmask))
185 return 0;
186
187 if (r->tos && (r->tos != fl4->flowi4_tos))
188 return 0;
189
190 if (rule->ip_proto && (rule->ip_proto != fl4->flowi4_proto))
191 return 0;
192
193 if (fib_rule_port_range_set(&rule->sport_range) &&
194 !fib_rule_port_inrange(&rule->sport_range, fl4->fl4_sport))
195 return 0;
196
197 if (fib_rule_port_range_set(&rule->dport_range) &&
198 !fib_rule_port_inrange(&rule->dport_range, fl4->fl4_dport))
199 return 0;
200
201 return 1;
202 }
203
fib_empty_table(struct net * net)204 static struct fib_table *fib_empty_table(struct net *net)
205 {
206 u32 id = 1;
207
208 while (1) {
209 if (!fib_get_table(net, id))
210 return fib_new_table(net, id);
211
212 if (id++ == RT_TABLE_MAX)
213 break;
214 }
215 return NULL;
216 }
217
218 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
219 FRA_GENERIC_POLICY,
220 [FRA_FLOW] = { .type = NLA_U32 },
221 };
222
fib4_rule_configure(struct fib_rule * rule,struct sk_buff * skb,struct fib_rule_hdr * frh,struct nlattr ** tb,struct netlink_ext_ack * extack)223 static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
224 struct fib_rule_hdr *frh,
225 struct nlattr **tb,
226 struct netlink_ext_ack *extack)
227 {
228 struct net *net = sock_net(skb->sk);
229 int err = -EINVAL;
230 struct fib4_rule *rule4 = (struct fib4_rule *) rule;
231
232 if (frh->tos & ~IPTOS_TOS_MASK) {
233 NL_SET_ERR_MSG(extack, "Invalid tos");
234 goto errout;
235 }
236
237 /* split local/main if they are not already split */
238 err = fib_unmerge(net);
239 if (err)
240 goto errout;
241
242 if (rule->table == RT_TABLE_UNSPEC && !rule->l3mdev) {
243 if (rule->action == FR_ACT_TO_TBL) {
244 struct fib_table *table;
245
246 table = fib_empty_table(net);
247 if (!table) {
248 err = -ENOBUFS;
249 goto errout;
250 }
251
252 rule->table = table->tb_id;
253 }
254 }
255
256 if (frh->src_len)
257 rule4->src = nla_get_in_addr(tb[FRA_SRC]);
258
259 if (frh->dst_len)
260 rule4->dst = nla_get_in_addr(tb[FRA_DST]);
261
262 #ifdef CONFIG_IP_ROUTE_CLASSID
263 if (tb[FRA_FLOW]) {
264 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
265 if (rule4->tclassid)
266 net->ipv4.fib_num_tclassid_users++;
267 }
268 #endif
269
270 if (fib_rule_requires_fldissect(rule))
271 net->ipv4.fib_rules_require_fldissect++;
272
273 rule4->src_len = frh->src_len;
274 rule4->srcmask = inet_make_mask(rule4->src_len);
275 rule4->dst_len = frh->dst_len;
276 rule4->dstmask = inet_make_mask(rule4->dst_len);
277 rule4->tos = frh->tos;
278
279 net->ipv4.fib_has_custom_rules = true;
280
281 err = 0;
282 errout:
283 return err;
284 }
285
fib4_rule_delete(struct fib_rule * rule)286 static int fib4_rule_delete(struct fib_rule *rule)
287 {
288 struct net *net = rule->fr_net;
289 int err;
290
291 /* split local/main if they are not already split */
292 err = fib_unmerge(net);
293 if (err)
294 goto errout;
295
296 #ifdef CONFIG_IP_ROUTE_CLASSID
297 if (((struct fib4_rule *)rule)->tclassid)
298 net->ipv4.fib_num_tclassid_users--;
299 #endif
300 net->ipv4.fib_has_custom_rules = true;
301
302 if (net->ipv4.fib_rules_require_fldissect &&
303 fib_rule_requires_fldissect(rule))
304 net->ipv4.fib_rules_require_fldissect--;
305 errout:
306 return err;
307 }
308
fib4_rule_compare(struct fib_rule * rule,struct fib_rule_hdr * frh,struct nlattr ** tb)309 static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
310 struct nlattr **tb)
311 {
312 struct fib4_rule *rule4 = (struct fib4_rule *) rule;
313
314 if (frh->src_len && (rule4->src_len != frh->src_len))
315 return 0;
316
317 if (frh->dst_len && (rule4->dst_len != frh->dst_len))
318 return 0;
319
320 if (frh->tos && (rule4->tos != frh->tos))
321 return 0;
322
323 #ifdef CONFIG_IP_ROUTE_CLASSID
324 if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
325 return 0;
326 #endif
327
328 if (frh->src_len && (rule4->src != nla_get_in_addr(tb[FRA_SRC])))
329 return 0;
330
331 if (frh->dst_len && (rule4->dst != nla_get_in_addr(tb[FRA_DST])))
332 return 0;
333
334 return 1;
335 }
336
fib4_rule_fill(struct fib_rule * rule,struct sk_buff * skb,struct fib_rule_hdr * frh)337 static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
338 struct fib_rule_hdr *frh)
339 {
340 struct fib4_rule *rule4 = (struct fib4_rule *) rule;
341
342 frh->dst_len = rule4->dst_len;
343 frh->src_len = rule4->src_len;
344 frh->tos = rule4->tos;
345
346 if ((rule4->dst_len &&
347 nla_put_in_addr(skb, FRA_DST, rule4->dst)) ||
348 (rule4->src_len &&
349 nla_put_in_addr(skb, FRA_SRC, rule4->src)))
350 goto nla_put_failure;
351 #ifdef CONFIG_IP_ROUTE_CLASSID
352 if (rule4->tclassid &&
353 nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
354 goto nla_put_failure;
355 #endif
356 return 0;
357
358 nla_put_failure:
359 return -ENOBUFS;
360 }
361
fib4_rule_nlmsg_payload(struct fib_rule * rule)362 static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
363 {
364 return nla_total_size(4) /* dst */
365 + nla_total_size(4) /* src */
366 + nla_total_size(4); /* flow */
367 }
368
fib4_rule_flush_cache(struct fib_rules_ops * ops)369 static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
370 {
371 rt_cache_flush(ops->fro_net);
372 }
373
374 static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {
375 .family = AF_INET,
376 .rule_size = sizeof(struct fib4_rule),
377 .addr_size = sizeof(u32),
378 .action = fib4_rule_action,
379 .suppress = fib4_rule_suppress,
380 .match = fib4_rule_match,
381 .configure = fib4_rule_configure,
382 .delete = fib4_rule_delete,
383 .compare = fib4_rule_compare,
384 .fill = fib4_rule_fill,
385 .nlmsg_payload = fib4_rule_nlmsg_payload,
386 .flush_cache = fib4_rule_flush_cache,
387 .nlgroup = RTNLGRP_IPV4_RULE,
388 .policy = fib4_rule_policy,
389 .owner = THIS_MODULE,
390 };
391
fib_default_rules_init(struct fib_rules_ops * ops)392 static int fib_default_rules_init(struct fib_rules_ops *ops)
393 {
394 int err;
395
396 err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
397 if (err < 0)
398 return err;
399 err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
400 if (err < 0)
401 return err;
402 err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
403 if (err < 0)
404 return err;
405 return 0;
406 }
407
fib4_rules_init(struct net * net)408 int __net_init fib4_rules_init(struct net *net)
409 {
410 int err;
411 struct fib_rules_ops *ops;
412
413 ops = fib_rules_register(&fib4_rules_ops_template, net);
414 if (IS_ERR(ops))
415 return PTR_ERR(ops);
416
417 err = fib_default_rules_init(ops);
418 if (err < 0)
419 goto fail;
420 net->ipv4.rules_ops = ops;
421 net->ipv4.fib_has_custom_rules = false;
422 net->ipv4.fib_rules_require_fldissect = 0;
423 return 0;
424
425 fail:
426 /* also cleans all rules already added */
427 fib_rules_unregister(ops);
428 return err;
429 }
430
fib4_rules_exit(struct net * net)431 void __net_exit fib4_rules_exit(struct net *net)
432 {
433 fib_rules_unregister(net->ipv4.rules_ops);
434 }
435
