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