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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, <[email protected]>
10 * Thomas Graf <[email protected]>
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/flow.h>
27#include <net/inet_dscp.h>
28#include <net/ip.h>
29#include <net/route.h>
30#include <net/tcp.h>
31#include <net/ip_fib.h>
32#include <net/nexthop.h>
33#include <net/fib_rules.h>
34#include <linux/indirect_call_wrapper.h>
35
36struct fib4_rule {
37 struct fib_rule common;
38 u8 dst_len;
39 u8 src_len;
40 dscp_t dscp;
41 dscp_t dscp_mask;
42 u8 dscp_full:1; /* DSCP or TOS selector */
43 __be32 src;
44 __be32 srcmask;
45 __be32 dst;
46 __be32 dstmask;
47#ifdef CONFIG_IP_ROUTE_CLASSID
48 u32 tclassid;
49#endif
50};
51
52static bool fib4_rule_matchall(const struct fib_rule *rule)
53{
54 struct fib4_rule *r = container_of(rule, struct fib4_rule, common);
55
56 if (r->dst_len || r->src_len || r->dscp)
57 return false;
58 return fib_rule_matchall(rule);
59}
60
61bool fib4_rule_default(const struct fib_rule *rule)
62{
63 if (!fib4_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL ||
64 rule->l3mdev)
65 return false;
66 if (rule->table != RT_TABLE_LOCAL && rule->table != RT_TABLE_MAIN &&
67 rule->table != RT_TABLE_DEFAULT)
68 return false;
69 return true;
70}
71EXPORT_SYMBOL_GPL(fib4_rule_default);
72
73int fib4_rules_dump(struct net *net, struct notifier_block *nb,
74 struct netlink_ext_ack *extack)
75{
76 return fib_rules_dump(net, nb, AF_INET, extack);
77}
78
79unsigned int fib4_rules_seq_read(const struct net *net)
80{
81 return fib_rules_seq_read(net, AF_INET);
82}
83
84int __fib_lookup(struct net *net, struct flowi4 *flp,
85 struct fib_result *res, unsigned int flags)
86{
87 struct fib_lookup_arg arg = {
88 .result = res,
89 .flags = flags,
90 };
91 int err;
92
93 /* update flow if oif or iif point to device enslaved to l3mdev */
94 l3mdev_update_flow(net, flowi4_to_flowi(flp));
95
96 err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);
97#ifdef CONFIG_IP_ROUTE_CLASSID
98 if (arg.rule)
99 res->tclassid = ((struct fib4_rule *)arg.rule)->tclassid;
100 else
101 res->tclassid = 0;
102#endif
103
104 if (err == -ESRCH)
105 err = -ENETUNREACH;
106
107 return err;
108}
109EXPORT_SYMBOL_GPL(__fib_lookup);
110
111INDIRECT_CALLABLE_SCOPE int fib4_rule_action(struct fib_rule *rule,
112 struct flowi *flp, int flags,
113 struct fib_lookup_arg *arg)
114{
115 int err = -EAGAIN;
116 struct fib_table *tbl;
117 u32 tb_id;
118
119 switch (rule->action) {
120 case FR_ACT_TO_TBL:
121 break;
122
123 case FR_ACT_UNREACHABLE:
124 return -ENETUNREACH;
125
126 case FR_ACT_PROHIBIT:
127 return -EACCES;
128
129 case FR_ACT_BLACKHOLE:
130 default:
131 return -EINVAL;
132 }
133
134 rcu_read_lock();
135
136 tb_id = fib_rule_get_table(rule, arg);
137 tbl = fib_get_table(rule->fr_net, tb_id);
138 if (tbl)
139 err = fib_table_lookup(tbl, &flp->u.ip4,
140 (struct fib_result *)arg->result,
141 arg->flags);
142
143 rcu_read_unlock();
144 return err;
145}
146
147INDIRECT_CALLABLE_SCOPE bool fib4_rule_suppress(struct fib_rule *rule,
148 int flags,
149 struct fib_lookup_arg *arg)
150{
151 struct fib_result *result = arg->result;
152 struct net_device *dev = NULL;
153
154 if (result->fi) {
155 struct fib_nh_common *nhc = fib_info_nhc(result->fi, 0);
156
157 dev = nhc->nhc_dev;
158 }
159
160 /* do not accept result if the route does
161 * not meet the required prefix length
162 */
163 if (result->prefixlen <= rule->suppress_prefixlen)
164 goto suppress_route;
165
166 /* do not accept result if the route uses a device
167 * belonging to a forbidden interface group
168 */
169 if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
170 goto suppress_route;
171
172 return false;
173
174suppress_route:
175 if (!(arg->flags & FIB_LOOKUP_NOREF))
176 fib_info_put(result->fi);
177 return true;
178}
179
180INDIRECT_CALLABLE_SCOPE int fib4_rule_match(struct fib_rule *rule,
181 struct flowi *fl, int flags)
182{
183 struct fib4_rule *r = (struct fib4_rule *) rule;
184 struct flowi4 *fl4 = &fl->u.ip4;
185 __be32 daddr = fl4->daddr;
186 __be32 saddr = fl4->saddr;
187
188 if (((saddr ^ r->src) & r->srcmask) ||
189 ((daddr ^ r->dst) & r->dstmask))
190 return 0;
191
192 /* When DSCP selector is used we need to match on the entire DSCP field
193 * in the flow information structure. When TOS selector is used we need
194 * to mask the upper three DSCP bits prior to matching to maintain
195 * legacy behavior.
196 */
197 if (r->dscp_full && (r->dscp ^ fl4->flowi4_dscp) & r->dscp_mask)
198 return 0;
199 else if (!r->dscp_full && r->dscp &&
200 !fib_dscp_masked_match(r->dscp, fl4))
201 return 0;
202
203 if (rule->ip_proto && (rule->ip_proto != fl4->flowi4_proto))
204 return 0;
205
206 if (!fib_rule_port_match(&rule->sport_range, rule->sport_mask,
207 fl4->fl4_sport))
208 return 0;
209
210 if (!fib_rule_port_match(&rule->dport_range, rule->dport_mask,
211 fl4->fl4_dport))
212 return 0;
213
214 return 1;
215}
216
217#define FIB_MAX_AUTO_TABLE_ID 4096
218
219static struct fib_table *fib_empty_table(struct net *net)
220{
221 u32 id = 1;
222
223 while (1) {
224 if (!fib_get_table(net, id))
225 return fib_new_table(net, id);
226
227 if (id++ == FIB_MAX_AUTO_TABLE_ID)
228 break;
229 }
230 return NULL;
231}
232
233static int fib4_nl2rule_dscp(const struct nlattr *nla, struct fib4_rule *rule4,
234 struct netlink_ext_ack *extack)
235{
236 if (rule4->dscp) {
237 NL_SET_ERR_MSG(extack, "Cannot specify both TOS and DSCP");
238 return -EINVAL;
239 }
240
241 rule4->dscp = inet_dsfield_to_dscp(nla_get_u8(nla) << 2);
242 rule4->dscp_mask = inet_dsfield_to_dscp(INET_DSCP_MASK);
243 rule4->dscp_full = true;
244
245 return 0;
246}
247
248static int fib4_nl2rule_dscp_mask(const struct nlattr *nla,
249 struct fib4_rule *rule4,
250 struct netlink_ext_ack *extack)
251{
252 dscp_t dscp_mask;
253
254 if (!rule4->dscp_full) {
255 NL_SET_ERR_MSG_ATTR(extack, nla,
256 "Cannot specify DSCP mask without DSCP value");
257 return -EINVAL;
258 }
259
260 dscp_mask = inet_dsfield_to_dscp(nla_get_u8(nla) << 2);
261 if (rule4->dscp & ~dscp_mask) {
262 NL_SET_ERR_MSG_ATTR(extack, nla, "Invalid DSCP mask");
263 return -EINVAL;
264 }
265
266 rule4->dscp_mask = dscp_mask;
267
268 return 0;
269}
270
271static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
272 struct fib_rule_hdr *frh,
273 struct nlattr **tb,
274 struct netlink_ext_ack *extack)
275{
276 struct fib4_rule *rule4 = (struct fib4_rule *)rule;
277 struct net *net = rule->fr_net;
278 int err = -EINVAL;
279
280 if (tb[FRA_FLOWLABEL] || tb[FRA_FLOWLABEL_MASK]) {
281 NL_SET_ERR_MSG(extack,
282 "Flow label cannot be specified for IPv4 FIB rules");
283 goto errout;
284 }
285
286 if (!inet_validate_dscp(frh->tos)) {
287 NL_SET_ERR_MSG(extack,
288 "Invalid dsfield (tos): ECN bits must be 0");
289 goto errout;
290 }
291 /* IPv4 currently doesn't handle high order DSCP bits correctly */
292 if (frh->tos & ~IPTOS_TOS_MASK) {
293 NL_SET_ERR_MSG(extack, "Invalid tos");
294 goto errout;
295 }
296 rule4->dscp = inet_dsfield_to_dscp(frh->tos);
297
298 if (tb[FRA_DSCP] &&
299 fib4_nl2rule_dscp(tb[FRA_DSCP], rule4, extack) < 0)
300 goto errout;
301
302 if (tb[FRA_DSCP_MASK] &&
303 fib4_nl2rule_dscp_mask(tb[FRA_DSCP_MASK], rule4, extack) < 0)
304 goto errout;
305
306 if (!net->ipv4.fib_has_custom_rules) {
307 /* split local/main if they are not already split */
308 err = fib_unmerge(net);
309 if (err)
310 goto errout;
311 }
312
313 if (rule->table == RT_TABLE_UNSPEC && !rule->l3mdev) {
314 if (rule->action == FR_ACT_TO_TBL) {
315 struct fib_table *table;
316
317 table = fib_empty_table(net);
318 if (!table) {
319 err = -ENOBUFS;
320 goto errout;
321 }
322
323 rule->table = table->tb_id;
324 }
325 }
326
327 if (frh->src_len)
328 rule4->src = nla_get_in_addr(tb[FRA_SRC]);
329
330 if (frh->dst_len)
331 rule4->dst = nla_get_in_addr(tb[FRA_DST]);
332
333#ifdef CONFIG_IP_ROUTE_CLASSID
334 if (tb[FRA_FLOW]) {
335 rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
336 if (rule4->tclassid)
337 atomic_inc(&net->ipv4.fib_num_tclassid_users);
338 }
339#endif
340
341 if (fib_rule_requires_fldissect(rule))
342 net->ipv4.fib_rules_require_fldissect++;
343
344 rule4->src_len = frh->src_len;
345 rule4->srcmask = inet_make_mask(rule4->src_len);
346 rule4->dst_len = frh->dst_len;
347 rule4->dstmask = inet_make_mask(rule4->dst_len);
348
349 net->ipv4.fib_has_custom_rules = true;
350
351 err = 0;
352errout:
353 return err;
354}
355
356static void fib4_rule_delete(struct fib_rule *rule)
357{
358 struct net *net = rule->fr_net;
359
360#ifdef CONFIG_IP_ROUTE_CLASSID
361 if (((struct fib4_rule *)rule)->tclassid)
362 atomic_dec(&net->ipv4.fib_num_tclassid_users);
363#endif
364
365 if (net->ipv4.fib_rules_require_fldissect &&
366 fib_rule_requires_fldissect(rule))
367 net->ipv4.fib_rules_require_fldissect--;
368}
369
370static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
371 struct nlattr **tb)
372{
373 struct fib4_rule *rule4 = (struct fib4_rule *) rule;
374
375 if (frh->src_len && (rule4->src_len != frh->src_len))
376 return 0;
377
378 if (frh->dst_len && (rule4->dst_len != frh->dst_len))
379 return 0;
380
381 if (frh->tos &&
382 (rule4->dscp_full ||
383 inet_dscp_to_dsfield(rule4->dscp) != frh->tos))
384 return 0;
385
386 if (tb[FRA_DSCP]) {
387 dscp_t dscp;
388
389 dscp = inet_dsfield_to_dscp(nla_get_u8(tb[FRA_DSCP]) << 2);
390 if (!rule4->dscp_full || rule4->dscp != dscp)
391 return 0;
392 }
393
394 if (tb[FRA_DSCP_MASK]) {
395 dscp_t dscp_mask;
396
397 dscp_mask = inet_dsfield_to_dscp(nla_get_u8(tb[FRA_DSCP_MASK]) << 2);
398 if (!rule4->dscp_full || rule4->dscp_mask != dscp_mask)
399 return 0;
400 }
401
402#ifdef CONFIG_IP_ROUTE_CLASSID
403 if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
404 return 0;
405#endif
406
407 if (frh->src_len && (rule4->src != nla_get_in_addr(tb[FRA_SRC])))
408 return 0;
409
410 if (frh->dst_len && (rule4->dst != nla_get_in_addr(tb[FRA_DST])))
411 return 0;
412
413 return 1;
414}
415
416static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
417 struct fib_rule_hdr *frh)
418{
419 struct fib4_rule *rule4 = (struct fib4_rule *) rule;
420
421 frh->dst_len = rule4->dst_len;
422 frh->src_len = rule4->src_len;
423
424 if (rule4->dscp_full) {
425 frh->tos = 0;
426 if (nla_put_u8(skb, FRA_DSCP,
427 inet_dscp_to_dsfield(rule4->dscp) >> 2) ||
428 nla_put_u8(skb, FRA_DSCP_MASK,
429 inet_dscp_to_dsfield(rule4->dscp_mask) >> 2))
430 goto nla_put_failure;
431 } else {
432 frh->tos = inet_dscp_to_dsfield(rule4->dscp);
433 }
434
435 if ((rule4->dst_len &&
436 nla_put_in_addr(skb, FRA_DST, rule4->dst)) ||
437 (rule4->src_len &&
438 nla_put_in_addr(skb, FRA_SRC, rule4->src)))
439 goto nla_put_failure;
440#ifdef CONFIG_IP_ROUTE_CLASSID
441 if (rule4->tclassid &&
442 nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
443 goto nla_put_failure;
444#endif
445 return 0;
446
447nla_put_failure:
448 return -ENOBUFS;
449}
450
451static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
452{
453 return nla_total_size(4) /* dst */
454 + nla_total_size(4) /* src */
455 + nla_total_size(4) /* flow */
456 + nla_total_size(1) /* dscp */
457 + nla_total_size(1); /* dscp mask */
458}
459
460static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
461{
462 rt_cache_flush(ops->fro_net);
463}
464
465static bool fib4_rule_need_rtnl(struct net *net)
466{
467 return !net->ipv4.fib_has_custom_rules;
468}
469
470static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {
471 .family = AF_INET,
472 .rule_size = sizeof(struct fib4_rule),
473 .addr_size = sizeof(u32),
474 .action = fib4_rule_action,
475 .suppress = fib4_rule_suppress,
476 .match = fib4_rule_match,
477 .configure = fib4_rule_configure,
478 .delete = fib4_rule_delete,
479 .compare = fib4_rule_compare,
480 .fill = fib4_rule_fill,
481 .nlmsg_payload = fib4_rule_nlmsg_payload,
482 .flush_cache = fib4_rule_flush_cache,
483 .need_rtnl = fib4_rule_need_rtnl,
484 .nlgroup = RTNLGRP_IPV4_RULE,
485 .owner = THIS_MODULE,
486};
487
488static int fib_default_rules_init(struct fib_rules_ops *ops)
489{
490 int err;
491
492 err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL);
493 if (err < 0)
494 return err;
495 err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN);
496 if (err < 0)
497 return err;
498 err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT);
499 if (err < 0)
500 return err;
501 return 0;
502}
503
504int __net_init fib4_rules_init(struct net *net)
505{
506 int err;
507 struct fib_rules_ops *ops;
508
509 ops = fib_rules_register(&fib4_rules_ops_template, net);
510 if (IS_ERR(ops))
511 return PTR_ERR(ops);
512
513 err = fib_default_rules_init(ops);
514 if (err < 0)
515 goto fail;
516 net->ipv4.rules_ops = ops;
517 net->ipv4.fib_has_custom_rules = false;
518 net->ipv4.fib_rules_require_fldissect = 0;
519 return 0;
520
521fail:
522 /* also cleans all rules already added */
523 fib_rules_unregister(ops);
524 return err;
525}
526
527void __net_exit fib4_rules_exit(struct net *net)
528{
529 fib_rules_unregister(net->ipv4.rules_ops);
530}