ipv4/inet_fragment.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * inet fragments management
   4  *
   5  *              Authors:        Pavel Emelyanov <xemul@openvz.org>
   6  *                              Started as consolidation of ipv4/ip_fragment.c,
   7  *                              ipv6/reassembly. and ipv6 nf conntrack reassembly
   8  */
   9
  10 #include <linux/list.h>
  11 #include <linux/spinlock.h>
  12 #include <linux/module.h>
  13 #include <linux/timer.h>
  14 #include <linux/mm.h>
  15 #include <linux/random.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/rtnetlink.h>
  18 #include <linux/slab.h>
  19 #include <linux/rhashtable.h>
  20
  21 #include <net/sock.h>
  22 #include <net/inet_frag.h>
  23 #include <net/inet_ecn.h>
  24 #include <net/ip.h>
  25 #include <net/ipv6.h>
  26
  27 #include "../core/sock_destructor.h"
  28
  29 /* Use skb->cb to track consecutive/adjacent fragments coming at
  30  * the end of the queue. Nodes in the rb-tree queue will
  31  * contain "runs" of one or more adjacent fragments.
  32  *
  33  * Invariants:
  34  * - next_frag is NULL at the tail of a "run";
  35  * - the head of a "run" has the sum of all fragment lengths in frag_run_len.
  36  */
  37 struct ipfrag_skb_cb {
  38         union {
  39                 struct inet_skb_parm    h4;
  40                 struct inet6_skb_parm   h6;
  41         };
  42         struct sk_buff          *next_frag;
  43         int                     frag_run_len;
  44         int                     ip_defrag_offset;
  45 };
  46
  47 #define FRAG_CB(skb)            ((struct ipfrag_skb_cb *)((skb)->cb))
  48
  49 static void fragcb_clear(struct sk_buff *skb)
  50 {
  51         RB_CLEAR_NODE(&skb->rbnode);
  52         FRAG_CB(skb)->next_frag = NULL;
  53         FRAG_CB(skb)->frag_run_len = skb->len;
  54 }
  55
  56 /* Append skb to the last "run". */
  57 static void fragrun_append_to_last(struct inet_frag_queue *q,
  58                                    struct sk_buff *skb)
  59 {
  60         fragcb_clear(skb);
  61
  62         FRAG_CB(q->last_run_head)->frag_run_len += skb->len;
  63         FRAG_CB(q->fragments_tail)->next_frag = skb;
  64         q->fragments_tail = skb;
  65 }
  66
  67 /* Create a new "run" with the skb. */
  68 static void fragrun_create(struct inet_frag_queue *q, struct sk_buff *skb)
  69 {
  70         BUILD_BUG_ON(sizeof(struct ipfrag_skb_cb) > sizeof(skb->cb));
  71         fragcb_clear(skb);
  72
  73         if (q->last_run_head)
  74                 rb_link_node(&skb->rbnode, &q->last_run_head->rbnode,
  75                              &q->last_run_head->rbnode.rb_right);
  76         else
  77                 rb_link_node(&skb->rbnode, NULL, &q->rb_fragments.rb_node);
  78         rb_insert_color(&skb->rbnode, &q->rb_fragments);
  79
  80         q->fragments_tail = skb;
  81         q->last_run_head = skb;
  82 }
  83
  84 /* Given the OR values of all fragments, apply RFC 3168 5.3 requirements
  85  * Value : 0xff if frame should be dropped.
  86  *         0 or INET_ECN_CE value, to be ORed in to final iph->tos field
  87  */
  88 const u8 ip_frag_ecn_table[16] = {
  89         /* at least one fragment had CE, and others ECT_0 or ECT_1 */
  90         [IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0]                      = INET_ECN_CE,
  91         [IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1]                      = INET_ECN_CE,
  92         [IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1]   = INET_ECN_CE,
  93
  94         /* invalid combinations : drop frame */
  95         [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE] = 0xff,
  96         [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0] = 0xff,
  97         [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_1] = 0xff,
  98         [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff,
  99         [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0] = 0xff,
 100         [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1] = 0xff,
 101         [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff,
 102 };
 103 EXPORT_SYMBOL(ip_frag_ecn_table);
 104
 105 int inet_frags_init(struct inet_frags *f)
 106 {
 107         f->frags_cachep = kmem_cache_create(f->frags_cache_name, f->qsize, 0, 0,
 108                                             NULL);
 109         if (!f->frags_cachep)
 110                 return -ENOMEM;
 111
 112         refcount_set(&f->refcnt, 1);
 113         init_completion(&f->completion);
 114         return 0;
 115 }
 116 EXPORT_SYMBOL(inet_frags_init);
 117
 118 void inet_frags_fini(struct inet_frags *f)
 119 {
 120         if (refcount_dec_and_test(&f->refcnt))
 121                 complete(&f->completion);
 122
 123         wait_for_completion(&f->completion);
 124
 125         kmem_cache_destroy(f->frags_cachep);
 126         f->frags_cachep = NULL;
 127 }
 128 EXPORT_SYMBOL(inet_frags_fini);
 129
 130 /* called from rhashtable_free_and_destroy() at netns_frags dismantle */
 131 static void inet_frags_free_cb(void *ptr, void *arg)
 132 {
 133         struct inet_frag_queue *fq = ptr;
 134         int count;
 135
 136         count = del_timer_sync(&fq->timer) ? 1 : 0;
 137
 138         spin_lock_bh(&fq->lock);
 139         fq->flags |= INET_FRAG_DROP;
 140         if (!(fq->flags & INET_FRAG_COMPLETE)) {
 141                 fq->flags |= INET_FRAG_COMPLETE;
 142                 count++;
 143         } else if (fq->flags & INET_FRAG_HASH_DEAD) {
 144                 count++;
 145         }
 146         spin_unlock_bh(&fq->lock);
 147
 148         if (refcount_sub_and_test(count, &fq->refcnt))
 149                 inet_frag_destroy(fq);
 150 }
 151
 152 static LLIST_HEAD(fqdir_free_list);
 153
 154 static void fqdir_free_fn(struct work_struct *work)
 155 {
 156         struct llist_node *kill_list;
 157         struct fqdir *fqdir, *tmp;
 158         struct inet_frags *f;
 159
 160         /* Atomically snapshot the list of fqdirs to free */
 161         kill_list = llist_del_all(&fqdir_free_list);
 162
 163         /* We need to make sure all ongoing call_rcu(..., inet_frag_destroy_rcu)
 164          * have completed, since they need to dereference fqdir.
 165          * Would it not be nice to have kfree_rcu_barrier() ? :)
 166          */
 167         rcu_barrier();
 168
 169         llist_for_each_entry_safe(fqdir, tmp, kill_list, free_list) {
 170                 f = fqdir->f;
 171                 if (refcount_dec_and_test(&f->refcnt))
 172                         complete(&f->completion);
 173
 174                 kfree(fqdir);
 175         }
 176 }
 177
 178 static DECLARE_WORK(fqdir_free_work, fqdir_free_fn);
 179
 180 static void fqdir_work_fn(struct work_struct *work)
 181 {
 182         struct fqdir *fqdir = container_of(work, struct fqdir, destroy_work);
 183
 184         rhashtable_free_and_destroy(&fqdir->rhashtable, inet_frags_free_cb, NULL);
 185
 186         if (llist_add(&fqdir->free_list, &fqdir_free_list))
 187                 queue_work(system_wq, &fqdir_free_work);
 188 }
 189
 190 int fqdir_init(struct fqdir **fqdirp, struct inet_frags *f, struct net *net)
 191 {
 192         struct fqdir *fqdir = kzalloc(sizeof(*fqdir), GFP_KERNEL);
 193         int res;
 194
 195         if (!fqdir)
 196                 return -ENOMEM;
 197         fqdir->f = f;
 198         fqdir->net = net;
 199         res = rhashtable_init(&fqdir->rhashtable, &fqdir->f->rhash_params);
 200         if (res < 0) {
 201                 kfree(fqdir);
 202                 return res;
 203         }
 204         refcount_inc(&f->refcnt);
 205         *fqdirp = fqdir;
 206         return 0;
 207 }
 208 EXPORT_SYMBOL(fqdir_init);
 209
 210 static struct workqueue_struct *inet_frag_wq;
 211
 212 static int __init inet_frag_wq_init(void)
 213 {
 214         inet_frag_wq = create_workqueue("inet_frag_wq");
 215         if (!inet_frag_wq)
 216                 panic("Could not create inet frag workq");
 217         return 0;
 218 }
 219
 220 pure_initcall(inet_frag_wq_init);
 221
 222 void fqdir_exit(struct fqdir *fqdir)
 223 {
 224         INIT_WORK(&fqdir->destroy_work, fqdir_work_fn);
 225         queue_work(inet_frag_wq, &fqdir->destroy_work);
 226 }
 227 EXPORT_SYMBOL(fqdir_exit);
 228
 229 void inet_frag_kill(struct inet_frag_queue *fq)
 230 {
 231         if (del_timer(&fq->timer))
 232                 refcount_dec(&fq->refcnt);
 233
 234         if (!(fq->flags & INET_FRAG_COMPLETE)) {
 235                 struct fqdir *fqdir = fq->fqdir;
 236
 237                 fq->flags |= INET_FRAG_COMPLETE;
 238                 rcu_read_lock();
 239                 /* The RCU read lock provides a memory barrier
 240                  * guaranteeing that if fqdir->dead is false then
 241                  * the hash table destruction will not start until
 242                  * after we unlock.  Paired with fqdir_pre_exit().
 243                  */
 244                 if (!READ_ONCE(fqdir->dead)) {
 245                         rhashtable_remove_fast(&fqdir->rhashtable, &fq->node,
 246                                                fqdir->f->rhash_params);
 247                         refcount_dec(&fq->refcnt);
 248                 } else {
 249                         fq->flags |= INET_FRAG_HASH_DEAD;
 250                 }
 251                 rcu_read_unlock();
 252         }
 253 }
 254 EXPORT_SYMBOL(inet_frag_kill);
 255
 256 static void inet_frag_destroy_rcu(struct rcu_head *head)
 257 {
 258         struct inet_frag_queue *q = container_of(head, struct inet_frag_queue,
 259                                                  rcu);
 260         struct inet_frags *f = q->fqdir->f;
 261
 262         if (f->destructor)
 263                 f->destructor(q);
 264         kmem_cache_free(f->frags_cachep, q);
 265 }
 266
 267 unsigned int inet_frag_rbtree_purge(struct rb_root *root,
 268                                     enum skb_drop_reason reason)
 269 {
 270         struct rb_node *p = rb_first(root);
 271         unsigned int sum = 0;
 272
 273         while (p) {
 274                 struct sk_buff *skb = rb_entry(p, struct sk_buff, rbnode);
 275
 276                 p = rb_next(p);
 277                 rb_erase(&skb->rbnode, root);
 278                 while (skb) {
 279                         struct sk_buff *next = FRAG_CB(skb)->next_frag;
 280
 281                         sum += skb->truesize;
 282                         kfree_skb_reason(skb, reason);
 283                         skb = next;
 284                 }
 285         }
 286         return sum;
 287 }
 288 EXPORT_SYMBOL(inet_frag_rbtree_purge);
 289
 290 void inet_frag_destroy(struct inet_frag_queue *q)
 291 {
 292         unsigned int sum, sum_truesize = 0;
 293         enum skb_drop_reason reason;
 294         struct inet_frags *f;
 295         struct fqdir *fqdir;
 296
 297         WARN_ON(!(q->flags & INET_FRAG_COMPLETE));
 298         reason = (q->flags & INET_FRAG_DROP) ?
 299                         SKB_DROP_REASON_FRAG_REASM_TIMEOUT :
 300                         SKB_CONSUMED;
 301         WARN_ON(del_timer(&q->timer) != 0);
 302
 303         /* Release all fragment data. */
 304         fqdir = q->fqdir;
 305         f = fqdir->f;
 306         sum_truesize = inet_frag_rbtree_purge(&q->rb_fragments, reason);
 307         sum = sum_truesize + f->qsize;
 308
 309         call_rcu(&q->rcu, inet_frag_destroy_rcu);
 310
 311         sub_frag_mem_limit(fqdir, sum);
 312 }
 313 EXPORT_SYMBOL(inet_frag_destroy);
 314
 315 static struct inet_frag_queue *inet_frag_alloc(struct fqdir *fqdir,
 316                                                struct inet_frags *f,
 317                                                void *arg)
 318 {
 319         struct inet_frag_queue *q;
 320
 321         q = kmem_cache_zalloc(f->frags_cachep, GFP_ATOMIC);
 322         if (!q)
 323                 return NULL;
 324
 325         q->fqdir = fqdir;
 326         f->constructor(q, arg);
 327         add_frag_mem_limit(fqdir, f->qsize);
 328
 329         timer_setup(&q->timer, f->frag_expire, 0);
 330         spin_lock_init(&q->lock);
 331         refcount_set(&q->refcnt, 3);
 332
 333         return q;
 334 }
 335
 336 static struct inet_frag_queue *inet_frag_create(struct fqdir *fqdir,
 337                                                 void *arg,
 338                                                 struct inet_frag_queue **prev)
 339 {
 340         struct inet_frags *f = fqdir->f;
 341         struct inet_frag_queue *q;
 342
 343         q = inet_frag_alloc(fqdir, f, arg);
 344         if (!q) {
 345                 *prev = ERR_PTR(-ENOMEM);
 346                 return NULL;
 347         }
 348         mod_timer(&q->timer, jiffies + fqdir->timeout);
 349
 350         *prev = rhashtable_lookup_get_insert_key(&fqdir->rhashtable, &q->key,
 351                                                  &q->node, f->rhash_params);
 352         if (*prev) {
 353                 q->flags |= INET_FRAG_COMPLETE;
 354                 inet_frag_kill(q);
 355                 inet_frag_destroy(q);
 356                 return NULL;
 357         }
 358         return q;
 359 }
 360
 361 /* TODO : call from rcu_read_lock() and no longer use refcount_inc_not_zero() */
 362 struct inet_frag_queue *inet_frag_find(struct fqdir *fqdir, void *key)
 363 {
 364         /* This pairs with WRITE_ONCE() in fqdir_pre_exit(). */
 365         long high_thresh = READ_ONCE(fqdir->high_thresh);
 366         struct inet_frag_queue *fq = NULL, *prev;
 367
 368         if (!high_thresh || frag_mem_limit(fqdir) > high_thresh)
 369                 return NULL;
 370
 371         rcu_read_lock();
 372
 373         prev = rhashtable_lookup(&fqdir->rhashtable, key, fqdir->f->rhash_params);
 374         if (!prev)
 375                 fq = inet_frag_create(fqdir, key, &prev);
 376         if (!IS_ERR_OR_NULL(prev)) {
 377                 fq = prev;
 378                 if (!refcount_inc_not_zero(&fq->refcnt))
 379                         fq = NULL;
 380         }
 381         rcu_read_unlock();
 382         return fq;
 383 }
 384 EXPORT_SYMBOL(inet_frag_find);
 385
 386 int inet_frag_queue_insert(struct inet_frag_queue *q, struct sk_buff *skb,
 387                            int offset, int end)
 388 {
 389         struct sk_buff *last = q->fragments_tail;
 390
 391         /* RFC5722, Section 4, amended by Errata ID : 3089
 392          *                          When reassembling an IPv6 datagram, if
 393          *   one or more its constituent fragments is determined to be an
 394          *   overlapping fragment, the entire datagram (and any constituent
 395          *   fragments) MUST be silently discarded.
 396          *
 397          * Duplicates, however, should be ignored (i.e. skb dropped, but the
 398          * queue/fragments kept for later reassembly).
 399          */
 400         if (!last)
 401                 fragrun_create(q, skb);  /* First fragment. */
 402         else if (FRAG_CB(last)->ip_defrag_offset + last->len < end) {
 403                 /* This is the common case: skb goes to the end. */
 404                 /* Detect and discard overlaps. */
 405                 if (offset < FRAG_CB(last)->ip_defrag_offset + last->len)
 406                         return IPFRAG_OVERLAP;
 407                 if (offset == FRAG_CB(last)->ip_defrag_offset + last->len)
 408                         fragrun_append_to_last(q, skb);
 409                 else
 410                         fragrun_create(q, skb);
 411         } else {
 412                 /* Binary search. Note that skb can become the first fragment,
 413                  * but not the last (covered above).
 414                  */
 415                 struct rb_node **rbn, *parent;
 416
 417                 rbn = &q->rb_fragments.rb_node;
 418                 do {
 419                         struct sk_buff *curr;
 420                         int curr_run_end;
 421
 422                         parent = *rbn;
 423                         curr = rb_to_skb(parent);
 424                         curr_run_end = FRAG_CB(curr)->ip_defrag_offset +
 425                                         FRAG_CB(curr)->frag_run_len;
 426                         if (end <= FRAG_CB(curr)->ip_defrag_offset)
 427                                 rbn = &parent->rb_left;
 428                         else if (offset >= curr_run_end)
 429                                 rbn = &parent->rb_right;
 430                         else if (offset >= FRAG_CB(curr)->ip_defrag_offset &&
 431                                  end <= curr_run_end)
 432                                 return IPFRAG_DUP;
 433                         else
 434                                 return IPFRAG_OVERLAP;
 435                 } while (*rbn);
 436                 /* Here we have parent properly set, and rbn pointing to
 437                  * one of its NULL left/right children. Insert skb.
 438                  */
 439                 fragcb_clear(skb);
 440                 rb_link_node(&skb->rbnode, parent, rbn);
 441                 rb_insert_color(&skb->rbnode, &q->rb_fragments);
 442         }
 443
 444         FRAG_CB(skb)->ip_defrag_offset = offset;
 445
 446         return IPFRAG_OK;
 447 }
 448 EXPORT_SYMBOL(inet_frag_queue_insert);
 449
 450 void *inet_frag_reasm_prepare(struct inet_frag_queue *q, struct sk_buff *skb,
 451                               struct sk_buff *parent)
 452 {
 453         struct sk_buff *fp, *head = skb_rb_first(&q->rb_fragments);
 454         void (*destructor)(struct sk_buff *);
 455         unsigned int orig_truesize = 0;
 456         struct sk_buff **nextp = NULL;
 457         struct sock *sk = skb->sk;
 458         int delta;
 459
 460         if (sk && is_skb_wmem(skb)) {
 461                 /* TX: skb->sk might have been passed as argument to
 462                  * dst->output and must remain valid until tx completes.
 463                  *
 464                  * Move sk to reassembled skb and fix up wmem accounting.
 465                  */
 466                 orig_truesize = skb->truesize;
 467                 destructor = skb->destructor;
 468         }
 469
 470         if (head != skb) {
 471                 fp = skb_clone(skb, GFP_ATOMIC);
 472                 if (!fp) {
 473                         head = skb;
 474                         goto out_restore_sk;
 475                 }
 476                 FRAG_CB(fp)->next_frag = FRAG_CB(skb)->next_frag;
 477                 if (RB_EMPTY_NODE(&skb->rbnode))
 478                         FRAG_CB(parent)->next_frag = fp;
 479                 else
 480                         rb_replace_node(&skb->rbnode, &fp->rbnode,
 481                                         &q->rb_fragments);
 482                 if (q->fragments_tail == skb)
 483                         q->fragments_tail = fp;
 484
 485                 if (orig_truesize) {
 486                         /* prevent skb_morph from releasing sk */
 487                         skb->sk = NULL;
 488                         skb->destructor = NULL;
 489                 }
 490                 skb_morph(skb, head);
 491                 FRAG_CB(skb)->next_frag = FRAG_CB(head)->next_frag;
 492                 rb_replace_node(&head->rbnode, &skb->rbnode,
 493                                 &q->rb_fragments);
 494                 consume_skb(head);
 495                 head = skb;
 496         }
 497         WARN_ON(FRAG_CB(head)->ip_defrag_offset != 0);
 498
 499         delta = -head->truesize;
 500
 501         /* Head of list must not be cloned. */
 502         if (skb_unclone(head, GFP_ATOMIC))
 503                 goto out_restore_sk;
 504
 505         delta += head->truesize;
 506         if (delta)
 507                 add_frag_mem_limit(q->fqdir, delta);
 508
 509         /* If the first fragment is fragmented itself, we split
 510          * it to two chunks: the first with data and paged part
 511          * and the second, holding only fragments.
 512          */
 513         if (skb_has_frag_list(head)) {
 514                 struct sk_buff *clone;
 515                 int i, plen = 0;
 516
 517                 clone = alloc_skb(0, GFP_ATOMIC);
 518                 if (!clone)
 519                         goto out_restore_sk;
 520                 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
 521                 skb_frag_list_init(head);
 522                 for (i = 0; i < skb_shinfo(head)->nr_frags; i++)
 523                         plen += skb_frag_size(&skb_shinfo(head)->frags[i]);
 524                 clone->data_len = head->data_len - plen;
 525                 clone->len = clone->data_len;
 526                 head->truesize += clone->truesize;
 527                 clone->csum = 0;
 528                 clone->ip_summed = head->ip_summed;
 529                 add_frag_mem_limit(q->fqdir, clone->truesize);
 530                 skb_shinfo(head)->frag_list = clone;
 531                 nextp = &clone->next;
 532         } else {
 533                 nextp = &skb_shinfo(head)->frag_list;
 534         }
 535
 536 out_restore_sk:
 537         if (orig_truesize) {
 538                 int ts_delta = head->truesize - orig_truesize;
 539
 540                 /* if this reassembled skb is fragmented later,
 541                  * fraglist skbs will get skb->sk assigned from head->sk,
 542                  * and each frag skb will be released via sock_wfree.
 543                  *
 544                  * Update sk_wmem_alloc.
 545                  */
 546                 head->sk = sk;
 547                 head->destructor = destructor;
 548                 refcount_add(ts_delta, &sk->sk_wmem_alloc);
 549         }
 550
 551         return nextp;
 552 }
 553 EXPORT_SYMBOL(inet_frag_reasm_prepare);
 554
 555 void inet_frag_reasm_finish(struct inet_frag_queue *q, struct sk_buff *head,
 556                             void *reasm_data, bool try_coalesce)
 557 {
 558         struct sock *sk = is_skb_wmem(head) ? head->sk : NULL;
 559         const unsigned int head_truesize = head->truesize;
 560         struct sk_buff **nextp = reasm_data;
 561         struct rb_node *rbn;
 562         struct sk_buff *fp;
 563         int sum_truesize;
 564
 565         skb_push(head, head->data - skb_network_header(head));
 566
 567         /* Traverse the tree in order, to build frag_list. */
 568         fp = FRAG_CB(head)->next_frag;
 569         rbn = rb_next(&head->rbnode);
 570         rb_erase(&head->rbnode, &q->rb_fragments);
 571
 572         sum_truesize = head->truesize;
 573         while (rbn || fp) {
 574                 /* fp points to the next sk_buff in the current run;
 575                  * rbn points to the next run.
 576                  */
 577                 /* Go through the current run. */
 578                 while (fp) {
 579                         struct sk_buff *next_frag = FRAG_CB(fp)->next_frag;
 580                         bool stolen;
 581                         int delta;
 582
 583                         sum_truesize += fp->truesize;
 584                         if (head->ip_summed != fp->ip_summed)
 585                                 head->ip_summed = CHECKSUM_NONE;
 586                         else if (head->ip_summed == CHECKSUM_COMPLETE)
 587                                 head->csum = csum_add(head->csum, fp->csum);
 588
 589                         if (try_coalesce && skb_try_coalesce(head, fp, &stolen,
 590                                                              &delta)) {
 591                                 kfree_skb_partial(fp, stolen);
 592                         } else {
 593                                 fp->prev = NULL;
 594                                 memset(&fp->rbnode, 0, sizeof(fp->rbnode));
 595                                 fp->sk = NULL;
 596
 597                                 head->data_len += fp->len;
 598                                 head->len += fp->len;
 599                                 head->truesize += fp->truesize;
 600
 601                                 *nextp = fp;
 602                                 nextp = &fp->next;
 603                         }
 604
 605                         fp = next_frag;
 606                 }
 607                 /* Move to the next run. */
 608                 if (rbn) {
 609                         struct rb_node *rbnext = rb_next(rbn);
 610
 611                         fp = rb_to_skb(rbn);
 612                         rb_erase(rbn, &q->rb_fragments);
 613                         rbn = rbnext;
 614                 }
 615         }
 616         sub_frag_mem_limit(q->fqdir, sum_truesize);
 617
 618         *nextp = NULL;
 619         skb_mark_not_on_list(head);
 620         head->prev = NULL;
 621         head->tstamp = q->stamp;
 622         head->mono_delivery_time = q->mono_delivery_time;
 623
 624         if (sk)
 625                 refcount_add(sum_truesize - head_truesize, &sk->sk_wmem_alloc);
 626 }
 627 EXPORT_SYMBOL(inet_frag_reasm_finish);
 628
 629 struct sk_buff *inet_frag_pull_head(struct inet_frag_queue *q)
 630 {
 631         struct sk_buff *head, *skb;
 632
 633         head = skb_rb_first(&q->rb_fragments);
 634         if (!head)
 635                 return NULL;
 636         skb = FRAG_CB(head)->next_frag;
 637         if (skb)
 638                 rb_replace_node(&head->rbnode, &skb->rbnode,
 639                                 &q->rb_fragments);
 640         else
 641                 rb_erase(&head->rbnode, &q->rb_fragments);
 642         memset(&head->rbnode, 0, sizeof(head->rbnode));
 643         barrier();
 644
 645         if (head == q->fragments_tail)
 646                 q->fragments_tail = NULL;
 647
 648         sub_frag_mem_limit(q->fqdir, head->truesize);
 649
 650         return head;
 651 }
 652 EXPORT_SYMBOL(inet_frag_pull_head);