Merge tag 'perf-tools-fixes-for-v6.6-2-2023-10-20' of git://git.kernel.org/pub/scm...
[platform/kernel/linux-rpi.git] / net / mctp / route.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Management Component Transport Protocol (MCTP) - routing
4  * implementation.
5  *
6  * This is currently based on a simple routing table, with no dst cache. The
7  * number of routes should stay fairly small, so the lookup cost is small.
8  *
9  * Copyright (c) 2021 Code Construct
10  * Copyright (c) 2021 Google
11  */
12
13 #include <linux/idr.h>
14 #include <linux/kconfig.h>
15 #include <linux/mctp.h>
16 #include <linux/netdevice.h>
17 #include <linux/rtnetlink.h>
18 #include <linux/skbuff.h>
19
20 #include <uapi/linux/if_arp.h>
21
22 #include <net/mctp.h>
23 #include <net/mctpdevice.h>
24 #include <net/netlink.h>
25 #include <net/sock.h>
26
27 #include <trace/events/mctp.h>
28
29 static const unsigned int mctp_message_maxlen = 64 * 1024;
30 static const unsigned long mctp_key_lifetime = 6 * CONFIG_HZ;
31
32 static void mctp_flow_prepare_output(struct sk_buff *skb, struct mctp_dev *dev);
33
34 /* route output callbacks */
35 static int mctp_route_discard(struct mctp_route *route, struct sk_buff *skb)
36 {
37         kfree_skb(skb);
38         return 0;
39 }
40
41 static struct mctp_sock *mctp_lookup_bind(struct net *net, struct sk_buff *skb)
42 {
43         struct mctp_skb_cb *cb = mctp_cb(skb);
44         struct mctp_hdr *mh;
45         struct sock *sk;
46         u8 type;
47
48         WARN_ON(!rcu_read_lock_held());
49
50         /* TODO: look up in skb->cb? */
51         mh = mctp_hdr(skb);
52
53         if (!skb_headlen(skb))
54                 return NULL;
55
56         type = (*(u8 *)skb->data) & 0x7f;
57
58         sk_for_each_rcu(sk, &net->mctp.binds) {
59                 struct mctp_sock *msk = container_of(sk, struct mctp_sock, sk);
60
61                 if (msk->bind_net != MCTP_NET_ANY && msk->bind_net != cb->net)
62                         continue;
63
64                 if (msk->bind_type != type)
65                         continue;
66
67                 if (!mctp_address_matches(msk->bind_addr, mh->dest))
68                         continue;
69
70                 return msk;
71         }
72
73         return NULL;
74 }
75
76 static bool mctp_key_match(struct mctp_sk_key *key, mctp_eid_t local,
77                            mctp_eid_t peer, u8 tag)
78 {
79         if (!mctp_address_matches(key->local_addr, local))
80                 return false;
81
82         if (key->peer_addr != peer)
83                 return false;
84
85         if (key->tag != tag)
86                 return false;
87
88         return true;
89 }
90
91 /* returns a key (with key->lock held, and refcounted), or NULL if no such
92  * key exists.
93  */
94 static struct mctp_sk_key *mctp_lookup_key(struct net *net, struct sk_buff *skb,
95                                            mctp_eid_t peer,
96                                            unsigned long *irqflags)
97         __acquires(&key->lock)
98 {
99         struct mctp_sk_key *key, *ret;
100         unsigned long flags;
101         struct mctp_hdr *mh;
102         u8 tag;
103
104         mh = mctp_hdr(skb);
105         tag = mh->flags_seq_tag & (MCTP_HDR_TAG_MASK | MCTP_HDR_FLAG_TO);
106
107         ret = NULL;
108         spin_lock_irqsave(&net->mctp.keys_lock, flags);
109
110         hlist_for_each_entry(key, &net->mctp.keys, hlist) {
111                 if (!mctp_key_match(key, mh->dest, peer, tag))
112                         continue;
113
114                 spin_lock(&key->lock);
115                 if (key->valid) {
116                         refcount_inc(&key->refs);
117                         ret = key;
118                         break;
119                 }
120                 spin_unlock(&key->lock);
121         }
122
123         if (ret) {
124                 spin_unlock(&net->mctp.keys_lock);
125                 *irqflags = flags;
126         } else {
127                 spin_unlock_irqrestore(&net->mctp.keys_lock, flags);
128         }
129
130         return ret;
131 }
132
133 static struct mctp_sk_key *mctp_key_alloc(struct mctp_sock *msk,
134                                           mctp_eid_t local, mctp_eid_t peer,
135                                           u8 tag, gfp_t gfp)
136 {
137         struct mctp_sk_key *key;
138
139         key = kzalloc(sizeof(*key), gfp);
140         if (!key)
141                 return NULL;
142
143         key->peer_addr = peer;
144         key->local_addr = local;
145         key->tag = tag;
146         key->sk = &msk->sk;
147         key->valid = true;
148         spin_lock_init(&key->lock);
149         refcount_set(&key->refs, 1);
150         sock_hold(key->sk);
151
152         return key;
153 }
154
155 void mctp_key_unref(struct mctp_sk_key *key)
156 {
157         unsigned long flags;
158
159         if (!refcount_dec_and_test(&key->refs))
160                 return;
161
162         /* even though no refs exist here, the lock allows us to stay
163          * consistent with the locking requirement of mctp_dev_release_key
164          */
165         spin_lock_irqsave(&key->lock, flags);
166         mctp_dev_release_key(key->dev, key);
167         spin_unlock_irqrestore(&key->lock, flags);
168
169         sock_put(key->sk);
170         kfree(key);
171 }
172
173 static int mctp_key_add(struct mctp_sk_key *key, struct mctp_sock *msk)
174 {
175         struct net *net = sock_net(&msk->sk);
176         struct mctp_sk_key *tmp;
177         unsigned long flags;
178         int rc = 0;
179
180         spin_lock_irqsave(&net->mctp.keys_lock, flags);
181
182         if (sock_flag(&msk->sk, SOCK_DEAD)) {
183                 rc = -EINVAL;
184                 goto out_unlock;
185         }
186
187         hlist_for_each_entry(tmp, &net->mctp.keys, hlist) {
188                 if (mctp_key_match(tmp, key->local_addr, key->peer_addr,
189                                    key->tag)) {
190                         spin_lock(&tmp->lock);
191                         if (tmp->valid)
192                                 rc = -EEXIST;
193                         spin_unlock(&tmp->lock);
194                         if (rc)
195                                 break;
196                 }
197         }
198
199         if (!rc) {
200                 refcount_inc(&key->refs);
201                 key->expiry = jiffies + mctp_key_lifetime;
202                 timer_reduce(&msk->key_expiry, key->expiry);
203
204                 hlist_add_head(&key->hlist, &net->mctp.keys);
205                 hlist_add_head(&key->sklist, &msk->keys);
206         }
207
208 out_unlock:
209         spin_unlock_irqrestore(&net->mctp.keys_lock, flags);
210
211         return rc;
212 }
213
214 /* Helper for mctp_route_input().
215  * We're done with the key; unlock and unref the key.
216  * For the usual case of automatic expiry we remove the key from lists.
217  * In the case that manual allocation is set on a key we release the lock
218  * and local ref, reset reassembly, but don't remove from lists.
219  */
220 static void __mctp_key_done_in(struct mctp_sk_key *key, struct net *net,
221                                unsigned long flags, unsigned long reason)
222 __releases(&key->lock)
223 {
224         struct sk_buff *skb;
225
226         trace_mctp_key_release(key, reason);
227         skb = key->reasm_head;
228         key->reasm_head = NULL;
229
230         if (!key->manual_alloc) {
231                 key->reasm_dead = true;
232                 key->valid = false;
233                 mctp_dev_release_key(key->dev, key);
234         }
235         spin_unlock_irqrestore(&key->lock, flags);
236
237         if (!key->manual_alloc) {
238                 spin_lock_irqsave(&net->mctp.keys_lock, flags);
239                 if (!hlist_unhashed(&key->hlist)) {
240                         hlist_del_init(&key->hlist);
241                         hlist_del_init(&key->sklist);
242                         mctp_key_unref(key);
243                 }
244                 spin_unlock_irqrestore(&net->mctp.keys_lock, flags);
245         }
246
247         /* and one for the local reference */
248         mctp_key_unref(key);
249
250         kfree_skb(skb);
251 }
252
253 #ifdef CONFIG_MCTP_FLOWS
254 static void mctp_skb_set_flow(struct sk_buff *skb, struct mctp_sk_key *key)
255 {
256         struct mctp_flow *flow;
257
258         flow = skb_ext_add(skb, SKB_EXT_MCTP);
259         if (!flow)
260                 return;
261
262         refcount_inc(&key->refs);
263         flow->key = key;
264 }
265
266 static void mctp_flow_prepare_output(struct sk_buff *skb, struct mctp_dev *dev)
267 {
268         struct mctp_sk_key *key;
269         struct mctp_flow *flow;
270
271         flow = skb_ext_find(skb, SKB_EXT_MCTP);
272         if (!flow)
273                 return;
274
275         key = flow->key;
276
277         if (WARN_ON(key->dev && key->dev != dev))
278                 return;
279
280         mctp_dev_set_key(dev, key);
281 }
282 #else
283 static void mctp_skb_set_flow(struct sk_buff *skb, struct mctp_sk_key *key) {}
284 static void mctp_flow_prepare_output(struct sk_buff *skb, struct mctp_dev *dev) {}
285 #endif
286
287 static int mctp_frag_queue(struct mctp_sk_key *key, struct sk_buff *skb)
288 {
289         struct mctp_hdr *hdr = mctp_hdr(skb);
290         u8 exp_seq, this_seq;
291
292         this_seq = (hdr->flags_seq_tag >> MCTP_HDR_SEQ_SHIFT)
293                 & MCTP_HDR_SEQ_MASK;
294
295         if (!key->reasm_head) {
296                 key->reasm_head = skb;
297                 key->reasm_tailp = &(skb_shinfo(skb)->frag_list);
298                 key->last_seq = this_seq;
299                 return 0;
300         }
301
302         exp_seq = (key->last_seq + 1) & MCTP_HDR_SEQ_MASK;
303
304         if (this_seq != exp_seq)
305                 return -EINVAL;
306
307         if (key->reasm_head->len + skb->len > mctp_message_maxlen)
308                 return -EINVAL;
309
310         skb->next = NULL;
311         skb->sk = NULL;
312         *key->reasm_tailp = skb;
313         key->reasm_tailp = &skb->next;
314
315         key->last_seq = this_seq;
316
317         key->reasm_head->data_len += skb->len;
318         key->reasm_head->len += skb->len;
319         key->reasm_head->truesize += skb->truesize;
320
321         return 0;
322 }
323
324 static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
325 {
326         struct mctp_sk_key *key, *any_key = NULL;
327         struct net *net = dev_net(skb->dev);
328         struct mctp_sock *msk;
329         struct mctp_hdr *mh;
330         unsigned long f;
331         u8 tag, flags;
332         int rc;
333
334         msk = NULL;
335         rc = -EINVAL;
336
337         /* we may be receiving a locally-routed packet; drop source sk
338          * accounting
339          */
340         skb_orphan(skb);
341
342         /* ensure we have enough data for a header and a type */
343         if (skb->len < sizeof(struct mctp_hdr) + 1)
344                 goto out;
345
346         /* grab header, advance data ptr */
347         mh = mctp_hdr(skb);
348         skb_pull(skb, sizeof(struct mctp_hdr));
349
350         if (mh->ver != 1)
351                 goto out;
352
353         flags = mh->flags_seq_tag & (MCTP_HDR_FLAG_SOM | MCTP_HDR_FLAG_EOM);
354         tag = mh->flags_seq_tag & (MCTP_HDR_TAG_MASK | MCTP_HDR_FLAG_TO);
355
356         rcu_read_lock();
357
358         /* lookup socket / reasm context, exactly matching (src,dest,tag).
359          * we hold a ref on the key, and key->lock held.
360          */
361         key = mctp_lookup_key(net, skb, mh->src, &f);
362
363         if (flags & MCTP_HDR_FLAG_SOM) {
364                 if (key) {
365                         msk = container_of(key->sk, struct mctp_sock, sk);
366                 } else {
367                         /* first response to a broadcast? do a more general
368                          * key lookup to find the socket, but don't use this
369                          * key for reassembly - we'll create a more specific
370                          * one for future packets if required (ie, !EOM).
371                          */
372                         any_key = mctp_lookup_key(net, skb, MCTP_ADDR_ANY, &f);
373                         if (any_key) {
374                                 msk = container_of(any_key->sk,
375                                                    struct mctp_sock, sk);
376                                 spin_unlock_irqrestore(&any_key->lock, f);
377                         }
378                 }
379
380                 if (!key && !msk && (tag & MCTP_HDR_FLAG_TO))
381                         msk = mctp_lookup_bind(net, skb);
382
383                 if (!msk) {
384                         rc = -ENOENT;
385                         goto out_unlock;
386                 }
387
388                 /* single-packet message? deliver to socket, clean up any
389                  * pending key.
390                  */
391                 if (flags & MCTP_HDR_FLAG_EOM) {
392                         sock_queue_rcv_skb(&msk->sk, skb);
393                         if (key) {
394                                 /* we've hit a pending reassembly; not much we
395                                  * can do but drop it
396                                  */
397                                 __mctp_key_done_in(key, net, f,
398                                                    MCTP_TRACE_KEY_REPLIED);
399                                 key = NULL;
400                         }
401                         rc = 0;
402                         goto out_unlock;
403                 }
404
405                 /* broadcast response or a bind() - create a key for further
406                  * packets for this message
407                  */
408                 if (!key) {
409                         key = mctp_key_alloc(msk, mh->dest, mh->src,
410                                              tag, GFP_ATOMIC);
411                         if (!key) {
412                                 rc = -ENOMEM;
413                                 goto out_unlock;
414                         }
415
416                         /* we can queue without the key lock here, as the
417                          * key isn't observable yet
418                          */
419                         mctp_frag_queue(key, skb);
420
421                         /* if the key_add fails, we've raced with another
422                          * SOM packet with the same src, dest and tag. There's
423                          * no way to distinguish future packets, so all we
424                          * can do is drop; we'll free the skb on exit from
425                          * this function.
426                          */
427                         rc = mctp_key_add(key, msk);
428                         if (!rc)
429                                 trace_mctp_key_acquire(key);
430
431                         /* we don't need to release key->lock on exit, so
432                          * clean up here and suppress the unlock via
433                          * setting to NULL
434                          */
435                         mctp_key_unref(key);
436                         key = NULL;
437
438                 } else {
439                         if (key->reasm_head || key->reasm_dead) {
440                                 /* duplicate start? drop everything */
441                                 __mctp_key_done_in(key, net, f,
442                                                    MCTP_TRACE_KEY_INVALIDATED);
443                                 rc = -EEXIST;
444                                 key = NULL;
445                         } else {
446                                 rc = mctp_frag_queue(key, skb);
447                         }
448                 }
449
450         } else if (key) {
451                 /* this packet continues a previous message; reassemble
452                  * using the message-specific key
453                  */
454
455                 /* we need to be continuing an existing reassembly... */
456                 if (!key->reasm_head)
457                         rc = -EINVAL;
458                 else
459                         rc = mctp_frag_queue(key, skb);
460
461                 /* end of message? deliver to socket, and we're done with
462                  * the reassembly/response key
463                  */
464                 if (!rc && flags & MCTP_HDR_FLAG_EOM) {
465                         sock_queue_rcv_skb(key->sk, key->reasm_head);
466                         key->reasm_head = NULL;
467                         __mctp_key_done_in(key, net, f, MCTP_TRACE_KEY_REPLIED);
468                         key = NULL;
469                 }
470
471         } else {
472                 /* not a start, no matching key */
473                 rc = -ENOENT;
474         }
475
476 out_unlock:
477         rcu_read_unlock();
478         if (key) {
479                 spin_unlock_irqrestore(&key->lock, f);
480                 mctp_key_unref(key);
481         }
482         if (any_key)
483                 mctp_key_unref(any_key);
484 out:
485         if (rc)
486                 kfree_skb(skb);
487         return rc;
488 }
489
490 static unsigned int mctp_route_mtu(struct mctp_route *rt)
491 {
492         return rt->mtu ?: READ_ONCE(rt->dev->dev->mtu);
493 }
494
495 static int mctp_route_output(struct mctp_route *route, struct sk_buff *skb)
496 {
497         struct mctp_skb_cb *cb = mctp_cb(skb);
498         struct mctp_hdr *hdr = mctp_hdr(skb);
499         char daddr_buf[MAX_ADDR_LEN];
500         char *daddr = NULL;
501         unsigned int mtu;
502         int rc;
503
504         skb->protocol = htons(ETH_P_MCTP);
505
506         mtu = READ_ONCE(skb->dev->mtu);
507         if (skb->len > mtu) {
508                 kfree_skb(skb);
509                 return -EMSGSIZE;
510         }
511
512         if (cb->ifindex) {
513                 /* direct route; use the hwaddr we stashed in sendmsg */
514                 if (cb->halen != skb->dev->addr_len) {
515                         /* sanity check, sendmsg should have already caught this */
516                         kfree_skb(skb);
517                         return -EMSGSIZE;
518                 }
519                 daddr = cb->haddr;
520         } else {
521                 /* If lookup fails let the device handle daddr==NULL */
522                 if (mctp_neigh_lookup(route->dev, hdr->dest, daddr_buf) == 0)
523                         daddr = daddr_buf;
524         }
525
526         rc = dev_hard_header(skb, skb->dev, ntohs(skb->protocol),
527                              daddr, skb->dev->dev_addr, skb->len);
528         if (rc < 0) {
529                 kfree_skb(skb);
530                 return -EHOSTUNREACH;
531         }
532
533         mctp_flow_prepare_output(skb, route->dev);
534
535         rc = dev_queue_xmit(skb);
536         if (rc)
537                 rc = net_xmit_errno(rc);
538
539         return rc;
540 }
541
542 /* route alloc/release */
543 static void mctp_route_release(struct mctp_route *rt)
544 {
545         if (refcount_dec_and_test(&rt->refs)) {
546                 mctp_dev_put(rt->dev);
547                 kfree_rcu(rt, rcu);
548         }
549 }
550
551 /* returns a route with the refcount at 1 */
552 static struct mctp_route *mctp_route_alloc(void)
553 {
554         struct mctp_route *rt;
555
556         rt = kzalloc(sizeof(*rt), GFP_KERNEL);
557         if (!rt)
558                 return NULL;
559
560         INIT_LIST_HEAD(&rt->list);
561         refcount_set(&rt->refs, 1);
562         rt->output = mctp_route_discard;
563
564         return rt;
565 }
566
567 unsigned int mctp_default_net(struct net *net)
568 {
569         return READ_ONCE(net->mctp.default_net);
570 }
571
572 int mctp_default_net_set(struct net *net, unsigned int index)
573 {
574         if (index == 0)
575                 return -EINVAL;
576         WRITE_ONCE(net->mctp.default_net, index);
577         return 0;
578 }
579
580 /* tag management */
581 static void mctp_reserve_tag(struct net *net, struct mctp_sk_key *key,
582                              struct mctp_sock *msk)
583 {
584         struct netns_mctp *mns = &net->mctp;
585
586         lockdep_assert_held(&mns->keys_lock);
587
588         key->expiry = jiffies + mctp_key_lifetime;
589         timer_reduce(&msk->key_expiry, key->expiry);
590
591         /* we hold the net->key_lock here, allowing updates to both
592          * then net and sk
593          */
594         hlist_add_head_rcu(&key->hlist, &mns->keys);
595         hlist_add_head_rcu(&key->sklist, &msk->keys);
596         refcount_inc(&key->refs);
597 }
598
599 /* Allocate a locally-owned tag value for (saddr, daddr), and reserve
600  * it for the socket msk
601  */
602 struct mctp_sk_key *mctp_alloc_local_tag(struct mctp_sock *msk,
603                                          mctp_eid_t daddr, mctp_eid_t saddr,
604                                          bool manual, u8 *tagp)
605 {
606         struct net *net = sock_net(&msk->sk);
607         struct netns_mctp *mns = &net->mctp;
608         struct mctp_sk_key *key, *tmp;
609         unsigned long flags;
610         u8 tagbits;
611
612         /* for NULL destination EIDs, we may get a response from any peer */
613         if (daddr == MCTP_ADDR_NULL)
614                 daddr = MCTP_ADDR_ANY;
615
616         /* be optimistic, alloc now */
617         key = mctp_key_alloc(msk, saddr, daddr, 0, GFP_KERNEL);
618         if (!key)
619                 return ERR_PTR(-ENOMEM);
620
621         /* 8 possible tag values */
622         tagbits = 0xff;
623
624         spin_lock_irqsave(&mns->keys_lock, flags);
625
626         /* Walk through the existing keys, looking for potential conflicting
627          * tags. If we find a conflict, clear that bit from tagbits
628          */
629         hlist_for_each_entry(tmp, &mns->keys, hlist) {
630                 /* We can check the lookup fields (*_addr, tag) without the
631                  * lock held, they don't change over the lifetime of the key.
632                  */
633
634                 /* if we don't own the tag, it can't conflict */
635                 if (tmp->tag & MCTP_HDR_FLAG_TO)
636                         continue;
637
638                 if (!(mctp_address_matches(tmp->peer_addr, daddr) &&
639                       mctp_address_matches(tmp->local_addr, saddr)))
640                         continue;
641
642                 spin_lock(&tmp->lock);
643                 /* key must still be valid. If we find a match, clear the
644                  * potential tag value
645                  */
646                 if (tmp->valid)
647                         tagbits &= ~(1 << tmp->tag);
648                 spin_unlock(&tmp->lock);
649
650                 if (!tagbits)
651                         break;
652         }
653
654         if (tagbits) {
655                 key->tag = __ffs(tagbits);
656                 mctp_reserve_tag(net, key, msk);
657                 trace_mctp_key_acquire(key);
658
659                 key->manual_alloc = manual;
660                 *tagp = key->tag;
661         }
662
663         spin_unlock_irqrestore(&mns->keys_lock, flags);
664
665         if (!tagbits) {
666                 kfree(key);
667                 return ERR_PTR(-EBUSY);
668         }
669
670         return key;
671 }
672
673 static struct mctp_sk_key *mctp_lookup_prealloc_tag(struct mctp_sock *msk,
674                                                     mctp_eid_t daddr,
675                                                     u8 req_tag, u8 *tagp)
676 {
677         struct net *net = sock_net(&msk->sk);
678         struct netns_mctp *mns = &net->mctp;
679         struct mctp_sk_key *key, *tmp;
680         unsigned long flags;
681
682         req_tag &= ~(MCTP_TAG_PREALLOC | MCTP_TAG_OWNER);
683         key = NULL;
684
685         spin_lock_irqsave(&mns->keys_lock, flags);
686
687         hlist_for_each_entry(tmp, &mns->keys, hlist) {
688                 if (tmp->tag != req_tag)
689                         continue;
690
691                 if (!mctp_address_matches(tmp->peer_addr, daddr))
692                         continue;
693
694                 if (!tmp->manual_alloc)
695                         continue;
696
697                 spin_lock(&tmp->lock);
698                 if (tmp->valid) {
699                         key = tmp;
700                         refcount_inc(&key->refs);
701                         spin_unlock(&tmp->lock);
702                         break;
703                 }
704                 spin_unlock(&tmp->lock);
705         }
706         spin_unlock_irqrestore(&mns->keys_lock, flags);
707
708         if (!key)
709                 return ERR_PTR(-ENOENT);
710
711         if (tagp)
712                 *tagp = key->tag;
713
714         return key;
715 }
716
717 /* routing lookups */
718 static bool mctp_rt_match_eid(struct mctp_route *rt,
719                               unsigned int net, mctp_eid_t eid)
720 {
721         return READ_ONCE(rt->dev->net) == net &&
722                 rt->min <= eid && rt->max >= eid;
723 }
724
725 /* compares match, used for duplicate prevention */
726 static bool mctp_rt_compare_exact(struct mctp_route *rt1,
727                                   struct mctp_route *rt2)
728 {
729         ASSERT_RTNL();
730         return rt1->dev->net == rt2->dev->net &&
731                 rt1->min == rt2->min &&
732                 rt1->max == rt2->max;
733 }
734
735 struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet,
736                                      mctp_eid_t daddr)
737 {
738         struct mctp_route *tmp, *rt = NULL;
739
740         rcu_read_lock();
741
742         list_for_each_entry_rcu(tmp, &net->mctp.routes, list) {
743                 /* TODO: add metrics */
744                 if (mctp_rt_match_eid(tmp, dnet, daddr)) {
745                         if (refcount_inc_not_zero(&tmp->refs)) {
746                                 rt = tmp;
747                                 break;
748                         }
749                 }
750         }
751
752         rcu_read_unlock();
753
754         return rt;
755 }
756
757 static struct mctp_route *mctp_route_lookup_null(struct net *net,
758                                                  struct net_device *dev)
759 {
760         struct mctp_route *tmp, *rt = NULL;
761
762         rcu_read_lock();
763
764         list_for_each_entry_rcu(tmp, &net->mctp.routes, list) {
765                 if (tmp->dev->dev == dev && tmp->type == RTN_LOCAL &&
766                     refcount_inc_not_zero(&tmp->refs)) {
767                         rt = tmp;
768                         break;
769                 }
770         }
771
772         rcu_read_unlock();
773
774         return rt;
775 }
776
777 static int mctp_do_fragment_route(struct mctp_route *rt, struct sk_buff *skb,
778                                   unsigned int mtu, u8 tag)
779 {
780         const unsigned int hlen = sizeof(struct mctp_hdr);
781         struct mctp_hdr *hdr, *hdr2;
782         unsigned int pos, size, headroom;
783         struct sk_buff *skb2;
784         int rc;
785         u8 seq;
786
787         hdr = mctp_hdr(skb);
788         seq = 0;
789         rc = 0;
790
791         if (mtu < hlen + 1) {
792                 kfree_skb(skb);
793                 return -EMSGSIZE;
794         }
795
796         /* keep same headroom as the original skb */
797         headroom = skb_headroom(skb);
798
799         /* we've got the header */
800         skb_pull(skb, hlen);
801
802         for (pos = 0; pos < skb->len;) {
803                 /* size of message payload */
804                 size = min(mtu - hlen, skb->len - pos);
805
806                 skb2 = alloc_skb(headroom + hlen + size, GFP_KERNEL);
807                 if (!skb2) {
808                         rc = -ENOMEM;
809                         break;
810                 }
811
812                 /* generic skb copy */
813                 skb2->protocol = skb->protocol;
814                 skb2->priority = skb->priority;
815                 skb2->dev = skb->dev;
816                 memcpy(skb2->cb, skb->cb, sizeof(skb2->cb));
817
818                 if (skb->sk)
819                         skb_set_owner_w(skb2, skb->sk);
820
821                 /* establish packet */
822                 skb_reserve(skb2, headroom);
823                 skb_reset_network_header(skb2);
824                 skb_put(skb2, hlen + size);
825                 skb2->transport_header = skb2->network_header + hlen;
826
827                 /* copy header fields, calculate SOM/EOM flags & seq */
828                 hdr2 = mctp_hdr(skb2);
829                 hdr2->ver = hdr->ver;
830                 hdr2->dest = hdr->dest;
831                 hdr2->src = hdr->src;
832                 hdr2->flags_seq_tag = tag &
833                         (MCTP_HDR_TAG_MASK | MCTP_HDR_FLAG_TO);
834
835                 if (pos == 0)
836                         hdr2->flags_seq_tag |= MCTP_HDR_FLAG_SOM;
837
838                 if (pos + size == skb->len)
839                         hdr2->flags_seq_tag |= MCTP_HDR_FLAG_EOM;
840
841                 hdr2->flags_seq_tag |= seq << MCTP_HDR_SEQ_SHIFT;
842
843                 /* copy message payload */
844                 skb_copy_bits(skb, pos, skb_transport_header(skb2), size);
845
846                 /* do route */
847                 rc = rt->output(rt, skb2);
848                 if (rc)
849                         break;
850
851                 seq = (seq + 1) & MCTP_HDR_SEQ_MASK;
852                 pos += size;
853         }
854
855         consume_skb(skb);
856         return rc;
857 }
858
859 int mctp_local_output(struct sock *sk, struct mctp_route *rt,
860                       struct sk_buff *skb, mctp_eid_t daddr, u8 req_tag)
861 {
862         struct mctp_sock *msk = container_of(sk, struct mctp_sock, sk);
863         struct mctp_skb_cb *cb = mctp_cb(skb);
864         struct mctp_route tmp_rt = {0};
865         struct mctp_sk_key *key;
866         struct mctp_hdr *hdr;
867         unsigned long flags;
868         unsigned int mtu;
869         mctp_eid_t saddr;
870         bool ext_rt;
871         int rc;
872         u8 tag;
873
874         rc = -ENODEV;
875
876         if (rt) {
877                 ext_rt = false;
878                 if (WARN_ON(!rt->dev))
879                         goto out_release;
880
881         } else if (cb->ifindex) {
882                 struct net_device *dev;
883
884                 ext_rt = true;
885                 rt = &tmp_rt;
886
887                 rcu_read_lock();
888                 dev = dev_get_by_index_rcu(sock_net(sk), cb->ifindex);
889                 if (!dev) {
890                         rcu_read_unlock();
891                         return rc;
892                 }
893                 rt->dev = __mctp_dev_get(dev);
894                 rcu_read_unlock();
895
896                 if (!rt->dev)
897                         goto out_release;
898
899                 /* establish temporary route - we set up enough to keep
900                  * mctp_route_output happy
901                  */
902                 rt->output = mctp_route_output;
903                 rt->mtu = 0;
904
905         } else {
906                 return -EINVAL;
907         }
908
909         spin_lock_irqsave(&rt->dev->addrs_lock, flags);
910         if (rt->dev->num_addrs == 0) {
911                 rc = -EHOSTUNREACH;
912         } else {
913                 /* use the outbound interface's first address as our source */
914                 saddr = rt->dev->addrs[0];
915                 rc = 0;
916         }
917         spin_unlock_irqrestore(&rt->dev->addrs_lock, flags);
918
919         if (rc)
920                 goto out_release;
921
922         if (req_tag & MCTP_TAG_OWNER) {
923                 if (req_tag & MCTP_TAG_PREALLOC)
924                         key = mctp_lookup_prealloc_tag(msk, daddr,
925                                                        req_tag, &tag);
926                 else
927                         key = mctp_alloc_local_tag(msk, daddr, saddr,
928                                                    false, &tag);
929
930                 if (IS_ERR(key)) {
931                         rc = PTR_ERR(key);
932                         goto out_release;
933                 }
934                 mctp_skb_set_flow(skb, key);
935                 /* done with the key in this scope */
936                 mctp_key_unref(key);
937                 tag |= MCTP_HDR_FLAG_TO;
938         } else {
939                 key = NULL;
940                 tag = req_tag & MCTP_TAG_MASK;
941         }
942
943         skb->protocol = htons(ETH_P_MCTP);
944         skb->priority = 0;
945         skb_reset_transport_header(skb);
946         skb_push(skb, sizeof(struct mctp_hdr));
947         skb_reset_network_header(skb);
948         skb->dev = rt->dev->dev;
949
950         /* cb->net will have been set on initial ingress */
951         cb->src = saddr;
952
953         /* set up common header fields */
954         hdr = mctp_hdr(skb);
955         hdr->ver = 1;
956         hdr->dest = daddr;
957         hdr->src = saddr;
958
959         mtu = mctp_route_mtu(rt);
960
961         if (skb->len + sizeof(struct mctp_hdr) <= mtu) {
962                 hdr->flags_seq_tag = MCTP_HDR_FLAG_SOM |
963                         MCTP_HDR_FLAG_EOM | tag;
964                 rc = rt->output(rt, skb);
965         } else {
966                 rc = mctp_do_fragment_route(rt, skb, mtu, tag);
967         }
968
969 out_release:
970         if (!ext_rt)
971                 mctp_route_release(rt);
972
973         mctp_dev_put(tmp_rt.dev);
974
975         return rc;
976 }
977
978 /* route management */
979 static int mctp_route_add(struct mctp_dev *mdev, mctp_eid_t daddr_start,
980                           unsigned int daddr_extent, unsigned int mtu,
981                           unsigned char type)
982 {
983         int (*rtfn)(struct mctp_route *rt, struct sk_buff *skb);
984         struct net *net = dev_net(mdev->dev);
985         struct mctp_route *rt, *ert;
986
987         if (!mctp_address_unicast(daddr_start))
988                 return -EINVAL;
989
990         if (daddr_extent > 0xff || daddr_start + daddr_extent >= 255)
991                 return -EINVAL;
992
993         switch (type) {
994         case RTN_LOCAL:
995                 rtfn = mctp_route_input;
996                 break;
997         case RTN_UNICAST:
998                 rtfn = mctp_route_output;
999                 break;
1000         default:
1001                 return -EINVAL;
1002         }
1003
1004         rt = mctp_route_alloc();
1005         if (!rt)
1006                 return -ENOMEM;
1007
1008         rt->min = daddr_start;
1009         rt->max = daddr_start + daddr_extent;
1010         rt->mtu = mtu;
1011         rt->dev = mdev;
1012         mctp_dev_hold(rt->dev);
1013         rt->type = type;
1014         rt->output = rtfn;
1015
1016         ASSERT_RTNL();
1017         /* Prevent duplicate identical routes. */
1018         list_for_each_entry(ert, &net->mctp.routes, list) {
1019                 if (mctp_rt_compare_exact(rt, ert)) {
1020                         mctp_route_release(rt);
1021                         return -EEXIST;
1022                 }
1023         }
1024
1025         list_add_rcu(&rt->list, &net->mctp.routes);
1026
1027         return 0;
1028 }
1029
1030 static int mctp_route_remove(struct mctp_dev *mdev, mctp_eid_t daddr_start,
1031                              unsigned int daddr_extent, unsigned char type)
1032 {
1033         struct net *net = dev_net(mdev->dev);
1034         struct mctp_route *rt, *tmp;
1035         mctp_eid_t daddr_end;
1036         bool dropped;
1037
1038         if (daddr_extent > 0xff || daddr_start + daddr_extent >= 255)
1039                 return -EINVAL;
1040
1041         daddr_end = daddr_start + daddr_extent;
1042         dropped = false;
1043
1044         ASSERT_RTNL();
1045
1046         list_for_each_entry_safe(rt, tmp, &net->mctp.routes, list) {
1047                 if (rt->dev == mdev &&
1048                     rt->min == daddr_start && rt->max == daddr_end &&
1049                     rt->type == type) {
1050                         list_del_rcu(&rt->list);
1051                         /* TODO: immediate RTM_DELROUTE */
1052                         mctp_route_release(rt);
1053                         dropped = true;
1054                 }
1055         }
1056
1057         return dropped ? 0 : -ENOENT;
1058 }
1059
1060 int mctp_route_add_local(struct mctp_dev *mdev, mctp_eid_t addr)
1061 {
1062         return mctp_route_add(mdev, addr, 0, 0, RTN_LOCAL);
1063 }
1064
1065 int mctp_route_remove_local(struct mctp_dev *mdev, mctp_eid_t addr)
1066 {
1067         return mctp_route_remove(mdev, addr, 0, RTN_LOCAL);
1068 }
1069
1070 /* removes all entries for a given device */
1071 void mctp_route_remove_dev(struct mctp_dev *mdev)
1072 {
1073         struct net *net = dev_net(mdev->dev);
1074         struct mctp_route *rt, *tmp;
1075
1076         ASSERT_RTNL();
1077         list_for_each_entry_safe(rt, tmp, &net->mctp.routes, list) {
1078                 if (rt->dev == mdev) {
1079                         list_del_rcu(&rt->list);
1080                         /* TODO: immediate RTM_DELROUTE */
1081                         mctp_route_release(rt);
1082                 }
1083         }
1084 }
1085
1086 /* Incoming packet-handling */
1087
1088 static int mctp_pkttype_receive(struct sk_buff *skb, struct net_device *dev,
1089                                 struct packet_type *pt,
1090                                 struct net_device *orig_dev)
1091 {
1092         struct net *net = dev_net(dev);
1093         struct mctp_dev *mdev;
1094         struct mctp_skb_cb *cb;
1095         struct mctp_route *rt;
1096         struct mctp_hdr *mh;
1097
1098         rcu_read_lock();
1099         mdev = __mctp_dev_get(dev);
1100         rcu_read_unlock();
1101         if (!mdev) {
1102                 /* basic non-data sanity checks */
1103                 goto err_drop;
1104         }
1105
1106         if (!pskb_may_pull(skb, sizeof(struct mctp_hdr)))
1107                 goto err_drop;
1108
1109         skb_reset_transport_header(skb);
1110         skb_reset_network_header(skb);
1111
1112         /* We have enough for a header; decode and route */
1113         mh = mctp_hdr(skb);
1114         if (mh->ver < MCTP_VER_MIN || mh->ver > MCTP_VER_MAX)
1115                 goto err_drop;
1116
1117         /* source must be valid unicast or null; drop reserved ranges and
1118          * broadcast
1119          */
1120         if (!(mctp_address_unicast(mh->src) || mctp_address_null(mh->src)))
1121                 goto err_drop;
1122
1123         /* dest address: as above, but allow broadcast */
1124         if (!(mctp_address_unicast(mh->dest) || mctp_address_null(mh->dest) ||
1125               mctp_address_broadcast(mh->dest)))
1126                 goto err_drop;
1127
1128         /* MCTP drivers must populate halen/haddr */
1129         if (dev->type == ARPHRD_MCTP) {
1130                 cb = mctp_cb(skb);
1131         } else {
1132                 cb = __mctp_cb(skb);
1133                 cb->halen = 0;
1134         }
1135         cb->net = READ_ONCE(mdev->net);
1136         cb->ifindex = dev->ifindex;
1137
1138         rt = mctp_route_lookup(net, cb->net, mh->dest);
1139
1140         /* NULL EID, but addressed to our physical address */
1141         if (!rt && mh->dest == MCTP_ADDR_NULL && skb->pkt_type == PACKET_HOST)
1142                 rt = mctp_route_lookup_null(net, dev);
1143
1144         if (!rt)
1145                 goto err_drop;
1146
1147         rt->output(rt, skb);
1148         mctp_route_release(rt);
1149         mctp_dev_put(mdev);
1150
1151         return NET_RX_SUCCESS;
1152
1153 err_drop:
1154         kfree_skb(skb);
1155         mctp_dev_put(mdev);
1156         return NET_RX_DROP;
1157 }
1158
1159 static struct packet_type mctp_packet_type = {
1160         .type = cpu_to_be16(ETH_P_MCTP),
1161         .func = mctp_pkttype_receive,
1162 };
1163
1164 /* netlink interface */
1165
1166 static const struct nla_policy rta_mctp_policy[RTA_MAX + 1] = {
1167         [RTA_DST]               = { .type = NLA_U8 },
1168         [RTA_METRICS]           = { .type = NLA_NESTED },
1169         [RTA_OIF]               = { .type = NLA_U32 },
1170 };
1171
1172 /* Common part for RTM_NEWROUTE and RTM_DELROUTE parsing.
1173  * tb must hold RTA_MAX+1 elements.
1174  */
1175 static int mctp_route_nlparse(struct sk_buff *skb, struct nlmsghdr *nlh,
1176                               struct netlink_ext_ack *extack,
1177                               struct nlattr **tb, struct rtmsg **rtm,
1178                               struct mctp_dev **mdev, mctp_eid_t *daddr_start)
1179 {
1180         struct net *net = sock_net(skb->sk);
1181         struct net_device *dev;
1182         unsigned int ifindex;
1183         int rc;
1184
1185         rc = nlmsg_parse(nlh, sizeof(struct rtmsg), tb, RTA_MAX,
1186                          rta_mctp_policy, extack);
1187         if (rc < 0) {
1188                 NL_SET_ERR_MSG(extack, "incorrect format");
1189                 return rc;
1190         }
1191
1192         if (!tb[RTA_DST]) {
1193                 NL_SET_ERR_MSG(extack, "dst EID missing");
1194                 return -EINVAL;
1195         }
1196         *daddr_start = nla_get_u8(tb[RTA_DST]);
1197
1198         if (!tb[RTA_OIF]) {
1199                 NL_SET_ERR_MSG(extack, "ifindex missing");
1200                 return -EINVAL;
1201         }
1202         ifindex = nla_get_u32(tb[RTA_OIF]);
1203
1204         *rtm = nlmsg_data(nlh);
1205         if ((*rtm)->rtm_family != AF_MCTP) {
1206                 NL_SET_ERR_MSG(extack, "route family must be AF_MCTP");
1207                 return -EINVAL;
1208         }
1209
1210         dev = __dev_get_by_index(net, ifindex);
1211         if (!dev) {
1212                 NL_SET_ERR_MSG(extack, "bad ifindex");
1213                 return -ENODEV;
1214         }
1215         *mdev = mctp_dev_get_rtnl(dev);
1216         if (!*mdev)
1217                 return -ENODEV;
1218
1219         if (dev->flags & IFF_LOOPBACK) {
1220                 NL_SET_ERR_MSG(extack, "no routes to loopback");
1221                 return -EINVAL;
1222         }
1223
1224         return 0;
1225 }
1226
1227 static const struct nla_policy rta_metrics_policy[RTAX_MAX + 1] = {
1228         [RTAX_MTU]              = { .type = NLA_U32 },
1229 };
1230
1231 static int mctp_newroute(struct sk_buff *skb, struct nlmsghdr *nlh,
1232                          struct netlink_ext_ack *extack)
1233 {
1234         struct nlattr *tb[RTA_MAX + 1];
1235         struct nlattr *tbx[RTAX_MAX + 1];
1236         mctp_eid_t daddr_start;
1237         struct mctp_dev *mdev;
1238         struct rtmsg *rtm;
1239         unsigned int mtu;
1240         int rc;
1241
1242         rc = mctp_route_nlparse(skb, nlh, extack, tb,
1243                                 &rtm, &mdev, &daddr_start);
1244         if (rc < 0)
1245                 return rc;
1246
1247         if (rtm->rtm_type != RTN_UNICAST) {
1248                 NL_SET_ERR_MSG(extack, "rtm_type must be RTN_UNICAST");
1249                 return -EINVAL;
1250         }
1251
1252         mtu = 0;
1253         if (tb[RTA_METRICS]) {
1254                 rc = nla_parse_nested(tbx, RTAX_MAX, tb[RTA_METRICS],
1255                                       rta_metrics_policy, NULL);
1256                 if (rc < 0)
1257                         return rc;
1258                 if (tbx[RTAX_MTU])
1259                         mtu = nla_get_u32(tbx[RTAX_MTU]);
1260         }
1261
1262         rc = mctp_route_add(mdev, daddr_start, rtm->rtm_dst_len, mtu,
1263                             rtm->rtm_type);
1264         return rc;
1265 }
1266
1267 static int mctp_delroute(struct sk_buff *skb, struct nlmsghdr *nlh,
1268                          struct netlink_ext_ack *extack)
1269 {
1270         struct nlattr *tb[RTA_MAX + 1];
1271         mctp_eid_t daddr_start;
1272         struct mctp_dev *mdev;
1273         struct rtmsg *rtm;
1274         int rc;
1275
1276         rc = mctp_route_nlparse(skb, nlh, extack, tb,
1277                                 &rtm, &mdev, &daddr_start);
1278         if (rc < 0)
1279                 return rc;
1280
1281         /* we only have unicast routes */
1282         if (rtm->rtm_type != RTN_UNICAST)
1283                 return -EINVAL;
1284
1285         rc = mctp_route_remove(mdev, daddr_start, rtm->rtm_dst_len, RTN_UNICAST);
1286         return rc;
1287 }
1288
1289 static int mctp_fill_rtinfo(struct sk_buff *skb, struct mctp_route *rt,
1290                             u32 portid, u32 seq, int event, unsigned int flags)
1291 {
1292         struct nlmsghdr *nlh;
1293         struct rtmsg *hdr;
1294         void *metrics;
1295
1296         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*hdr), flags);
1297         if (!nlh)
1298                 return -EMSGSIZE;
1299
1300         hdr = nlmsg_data(nlh);
1301         hdr->rtm_family = AF_MCTP;
1302
1303         /* we use the _len fields as a number of EIDs, rather than
1304          * a number of bits in the address
1305          */
1306         hdr->rtm_dst_len = rt->max - rt->min;
1307         hdr->rtm_src_len = 0;
1308         hdr->rtm_tos = 0;
1309         hdr->rtm_table = RT_TABLE_DEFAULT;
1310         hdr->rtm_protocol = RTPROT_STATIC; /* everything is user-defined */
1311         hdr->rtm_scope = RT_SCOPE_LINK; /* TODO: scope in mctp_route? */
1312         hdr->rtm_type = rt->type;
1313
1314         if (nla_put_u8(skb, RTA_DST, rt->min))
1315                 goto cancel;
1316
1317         metrics = nla_nest_start_noflag(skb, RTA_METRICS);
1318         if (!metrics)
1319                 goto cancel;
1320
1321         if (rt->mtu) {
1322                 if (nla_put_u32(skb, RTAX_MTU, rt->mtu))
1323                         goto cancel;
1324         }
1325
1326         nla_nest_end(skb, metrics);
1327
1328         if (rt->dev) {
1329                 if (nla_put_u32(skb, RTA_OIF, rt->dev->dev->ifindex))
1330                         goto cancel;
1331         }
1332
1333         /* TODO: conditional neighbour physaddr? */
1334
1335         nlmsg_end(skb, nlh);
1336
1337         return 0;
1338
1339 cancel:
1340         nlmsg_cancel(skb, nlh);
1341         return -EMSGSIZE;
1342 }
1343
1344 static int mctp_dump_rtinfo(struct sk_buff *skb, struct netlink_callback *cb)
1345 {
1346         struct net *net = sock_net(skb->sk);
1347         struct mctp_route *rt;
1348         int s_idx, idx;
1349
1350         /* TODO: allow filtering on route data, possibly under
1351          * cb->strict_check
1352          */
1353
1354         /* TODO: change to struct overlay */
1355         s_idx = cb->args[0];
1356         idx = 0;
1357
1358         rcu_read_lock();
1359         list_for_each_entry_rcu(rt, &net->mctp.routes, list) {
1360                 if (idx++ < s_idx)
1361                         continue;
1362                 if (mctp_fill_rtinfo(skb, rt,
1363                                      NETLINK_CB(cb->skb).portid,
1364                                      cb->nlh->nlmsg_seq,
1365                                      RTM_NEWROUTE, NLM_F_MULTI) < 0)
1366                         break;
1367         }
1368
1369         rcu_read_unlock();
1370         cb->args[0] = idx;
1371
1372         return skb->len;
1373 }
1374
1375 /* net namespace implementation */
1376 static int __net_init mctp_routes_net_init(struct net *net)
1377 {
1378         struct netns_mctp *ns = &net->mctp;
1379
1380         INIT_LIST_HEAD(&ns->routes);
1381         INIT_HLIST_HEAD(&ns->binds);
1382         mutex_init(&ns->bind_lock);
1383         INIT_HLIST_HEAD(&ns->keys);
1384         spin_lock_init(&ns->keys_lock);
1385         WARN_ON(mctp_default_net_set(net, MCTP_INITIAL_DEFAULT_NET));
1386         return 0;
1387 }
1388
1389 static void __net_exit mctp_routes_net_exit(struct net *net)
1390 {
1391         struct mctp_route *rt;
1392
1393         rcu_read_lock();
1394         list_for_each_entry_rcu(rt, &net->mctp.routes, list)
1395                 mctp_route_release(rt);
1396         rcu_read_unlock();
1397 }
1398
1399 static struct pernet_operations mctp_net_ops = {
1400         .init = mctp_routes_net_init,
1401         .exit = mctp_routes_net_exit,
1402 };
1403
1404 int __init mctp_routes_init(void)
1405 {
1406         dev_add_pack(&mctp_packet_type);
1407
1408         rtnl_register_module(THIS_MODULE, PF_MCTP, RTM_GETROUTE,
1409                              NULL, mctp_dump_rtinfo, 0);
1410         rtnl_register_module(THIS_MODULE, PF_MCTP, RTM_NEWROUTE,
1411                              mctp_newroute, NULL, 0);
1412         rtnl_register_module(THIS_MODULE, PF_MCTP, RTM_DELROUTE,
1413                              mctp_delroute, NULL, 0);
1414
1415         return register_pernet_subsys(&mctp_net_ops);
1416 }
1417
1418 void mctp_routes_exit(void)
1419 {
1420         unregister_pernet_subsys(&mctp_net_ops);
1421         rtnl_unregister(PF_MCTP, RTM_DELROUTE);
1422         rtnl_unregister(PF_MCTP, RTM_NEWROUTE);
1423         rtnl_unregister(PF_MCTP, RTM_GETROUTE);
1424         dev_remove_pack(&mctp_packet_type);
1425 }
1426
1427 #if IS_ENABLED(CONFIG_MCTP_TEST)
1428 #include "test/route-test.c"
1429 #endif