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![Yu Zhe](/assets/img/avatar_default.png)
remove unnecessary void* type castings. Signed-off-by: Yu Zhe <yuzhe@nfschina.com> Signed-off-by: David S. Miller <davem@davemloft.net>
602 lines
15 KiB
C
602 lines
15 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* inet fragments management
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*
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* Authors: Pavel Emelyanov <xemul@openvz.org>
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* Started as consolidation of ipv4/ip_fragment.c,
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* ipv6/reassembly. and ipv6 nf conntrack reassembly
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*/
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#include <linux/list.h>
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#include <linux/spinlock.h>
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#include <linux/module.h>
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#include <linux/timer.h>
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#include <linux/mm.h>
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#include <linux/random.h>
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#include <linux/skbuff.h>
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#include <linux/rtnetlink.h>
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#include <linux/slab.h>
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#include <linux/rhashtable.h>
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#include <net/sock.h>
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#include <net/inet_frag.h>
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#include <net/inet_ecn.h>
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#include <net/ip.h>
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#include <net/ipv6.h>
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/* Use skb->cb to track consecutive/adjacent fragments coming at
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* the end of the queue. Nodes in the rb-tree queue will
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* contain "runs" of one or more adjacent fragments.
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*
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* Invariants:
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* - next_frag is NULL at the tail of a "run";
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* - the head of a "run" has the sum of all fragment lengths in frag_run_len.
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*/
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struct ipfrag_skb_cb {
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union {
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struct inet_skb_parm h4;
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struct inet6_skb_parm h6;
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};
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struct sk_buff *next_frag;
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int frag_run_len;
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};
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#define FRAG_CB(skb) ((struct ipfrag_skb_cb *)((skb)->cb))
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static void fragcb_clear(struct sk_buff *skb)
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{
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RB_CLEAR_NODE(&skb->rbnode);
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FRAG_CB(skb)->next_frag = NULL;
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FRAG_CB(skb)->frag_run_len = skb->len;
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}
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/* Append skb to the last "run". */
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static void fragrun_append_to_last(struct inet_frag_queue *q,
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struct sk_buff *skb)
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{
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fragcb_clear(skb);
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FRAG_CB(q->last_run_head)->frag_run_len += skb->len;
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FRAG_CB(q->fragments_tail)->next_frag = skb;
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q->fragments_tail = skb;
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}
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/* Create a new "run" with the skb. */
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static void fragrun_create(struct inet_frag_queue *q, struct sk_buff *skb)
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{
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BUILD_BUG_ON(sizeof(struct ipfrag_skb_cb) > sizeof(skb->cb));
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fragcb_clear(skb);
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if (q->last_run_head)
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rb_link_node(&skb->rbnode, &q->last_run_head->rbnode,
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&q->last_run_head->rbnode.rb_right);
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else
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rb_link_node(&skb->rbnode, NULL, &q->rb_fragments.rb_node);
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rb_insert_color(&skb->rbnode, &q->rb_fragments);
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q->fragments_tail = skb;
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q->last_run_head = skb;
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}
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/* Given the OR values of all fragments, apply RFC 3168 5.3 requirements
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* Value : 0xff if frame should be dropped.
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* 0 or INET_ECN_CE value, to be ORed in to final iph->tos field
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*/
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const u8 ip_frag_ecn_table[16] = {
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/* at least one fragment had CE, and others ECT_0 or ECT_1 */
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[IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0] = INET_ECN_CE,
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[IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1] = INET_ECN_CE,
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[IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = INET_ECN_CE,
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/* invalid combinations : drop frame */
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[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE] = 0xff,
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[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0] = 0xff,
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[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_1] = 0xff,
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[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff,
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[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0] = 0xff,
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[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1] = 0xff,
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[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff,
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};
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EXPORT_SYMBOL(ip_frag_ecn_table);
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int inet_frags_init(struct inet_frags *f)
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{
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f->frags_cachep = kmem_cache_create(f->frags_cache_name, f->qsize, 0, 0,
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NULL);
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if (!f->frags_cachep)
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return -ENOMEM;
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refcount_set(&f->refcnt, 1);
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init_completion(&f->completion);
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return 0;
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}
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EXPORT_SYMBOL(inet_frags_init);
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void inet_frags_fini(struct inet_frags *f)
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{
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if (refcount_dec_and_test(&f->refcnt))
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complete(&f->completion);
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wait_for_completion(&f->completion);
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kmem_cache_destroy(f->frags_cachep);
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f->frags_cachep = NULL;
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}
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EXPORT_SYMBOL(inet_frags_fini);
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/* called from rhashtable_free_and_destroy() at netns_frags dismantle */
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static void inet_frags_free_cb(void *ptr, void *arg)
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{
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struct inet_frag_queue *fq = ptr;
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int count;
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count = del_timer_sync(&fq->timer) ? 1 : 0;
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spin_lock_bh(&fq->lock);
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if (!(fq->flags & INET_FRAG_COMPLETE)) {
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fq->flags |= INET_FRAG_COMPLETE;
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count++;
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} else if (fq->flags & INET_FRAG_HASH_DEAD) {
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count++;
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}
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spin_unlock_bh(&fq->lock);
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if (refcount_sub_and_test(count, &fq->refcnt))
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inet_frag_destroy(fq);
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}
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static LLIST_HEAD(fqdir_free_list);
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static void fqdir_free_fn(struct work_struct *work)
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{
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struct llist_node *kill_list;
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struct fqdir *fqdir, *tmp;
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struct inet_frags *f;
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/* Atomically snapshot the list of fqdirs to free */
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kill_list = llist_del_all(&fqdir_free_list);
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/* We need to make sure all ongoing call_rcu(..., inet_frag_destroy_rcu)
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* have completed, since they need to dereference fqdir.
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* Would it not be nice to have kfree_rcu_barrier() ? :)
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*/
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rcu_barrier();
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llist_for_each_entry_safe(fqdir, tmp, kill_list, free_list) {
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f = fqdir->f;
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if (refcount_dec_and_test(&f->refcnt))
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complete(&f->completion);
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kfree(fqdir);
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}
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}
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static DECLARE_WORK(fqdir_free_work, fqdir_free_fn);
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static void fqdir_work_fn(struct work_struct *work)
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{
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struct fqdir *fqdir = container_of(work, struct fqdir, destroy_work);
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rhashtable_free_and_destroy(&fqdir->rhashtable, inet_frags_free_cb, NULL);
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if (llist_add(&fqdir->free_list, &fqdir_free_list))
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queue_work(system_wq, &fqdir_free_work);
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}
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int fqdir_init(struct fqdir **fqdirp, struct inet_frags *f, struct net *net)
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{
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struct fqdir *fqdir = kzalloc(sizeof(*fqdir), GFP_KERNEL);
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int res;
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if (!fqdir)
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return -ENOMEM;
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fqdir->f = f;
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fqdir->net = net;
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res = rhashtable_init(&fqdir->rhashtable, &fqdir->f->rhash_params);
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if (res < 0) {
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kfree(fqdir);
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return res;
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}
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refcount_inc(&f->refcnt);
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*fqdirp = fqdir;
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return 0;
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}
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EXPORT_SYMBOL(fqdir_init);
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static struct workqueue_struct *inet_frag_wq;
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static int __init inet_frag_wq_init(void)
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{
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inet_frag_wq = create_workqueue("inet_frag_wq");
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if (!inet_frag_wq)
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panic("Could not create inet frag workq");
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return 0;
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}
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pure_initcall(inet_frag_wq_init);
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void fqdir_exit(struct fqdir *fqdir)
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{
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INIT_WORK(&fqdir->destroy_work, fqdir_work_fn);
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queue_work(inet_frag_wq, &fqdir->destroy_work);
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}
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EXPORT_SYMBOL(fqdir_exit);
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void inet_frag_kill(struct inet_frag_queue *fq)
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{
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if (del_timer(&fq->timer))
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refcount_dec(&fq->refcnt);
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if (!(fq->flags & INET_FRAG_COMPLETE)) {
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struct fqdir *fqdir = fq->fqdir;
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fq->flags |= INET_FRAG_COMPLETE;
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rcu_read_lock();
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/* The RCU read lock provides a memory barrier
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* guaranteeing that if fqdir->dead is false then
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* the hash table destruction will not start until
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* after we unlock. Paired with fqdir_pre_exit().
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*/
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if (!READ_ONCE(fqdir->dead)) {
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rhashtable_remove_fast(&fqdir->rhashtable, &fq->node,
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fqdir->f->rhash_params);
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refcount_dec(&fq->refcnt);
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} else {
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fq->flags |= INET_FRAG_HASH_DEAD;
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}
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rcu_read_unlock();
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}
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}
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EXPORT_SYMBOL(inet_frag_kill);
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static void inet_frag_destroy_rcu(struct rcu_head *head)
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{
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struct inet_frag_queue *q = container_of(head, struct inet_frag_queue,
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rcu);
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struct inet_frags *f = q->fqdir->f;
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if (f->destructor)
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f->destructor(q);
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kmem_cache_free(f->frags_cachep, q);
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}
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unsigned int inet_frag_rbtree_purge(struct rb_root *root)
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{
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struct rb_node *p = rb_first(root);
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unsigned int sum = 0;
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while (p) {
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struct sk_buff *skb = rb_entry(p, struct sk_buff, rbnode);
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p = rb_next(p);
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rb_erase(&skb->rbnode, root);
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while (skb) {
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struct sk_buff *next = FRAG_CB(skb)->next_frag;
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sum += skb->truesize;
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kfree_skb(skb);
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skb = next;
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}
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}
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return sum;
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}
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EXPORT_SYMBOL(inet_frag_rbtree_purge);
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void inet_frag_destroy(struct inet_frag_queue *q)
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{
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struct fqdir *fqdir;
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unsigned int sum, sum_truesize = 0;
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struct inet_frags *f;
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WARN_ON(!(q->flags & INET_FRAG_COMPLETE));
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WARN_ON(del_timer(&q->timer) != 0);
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/* Release all fragment data. */
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fqdir = q->fqdir;
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f = fqdir->f;
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sum_truesize = inet_frag_rbtree_purge(&q->rb_fragments);
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sum = sum_truesize + f->qsize;
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call_rcu(&q->rcu, inet_frag_destroy_rcu);
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sub_frag_mem_limit(fqdir, sum);
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}
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EXPORT_SYMBOL(inet_frag_destroy);
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static struct inet_frag_queue *inet_frag_alloc(struct fqdir *fqdir,
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struct inet_frags *f,
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void *arg)
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{
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struct inet_frag_queue *q;
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q = kmem_cache_zalloc(f->frags_cachep, GFP_ATOMIC);
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if (!q)
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return NULL;
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q->fqdir = fqdir;
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f->constructor(q, arg);
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add_frag_mem_limit(fqdir, f->qsize);
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timer_setup(&q->timer, f->frag_expire, 0);
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spin_lock_init(&q->lock);
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refcount_set(&q->refcnt, 3);
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return q;
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}
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static struct inet_frag_queue *inet_frag_create(struct fqdir *fqdir,
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void *arg,
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struct inet_frag_queue **prev)
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{
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struct inet_frags *f = fqdir->f;
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struct inet_frag_queue *q;
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q = inet_frag_alloc(fqdir, f, arg);
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if (!q) {
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*prev = ERR_PTR(-ENOMEM);
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return NULL;
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}
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mod_timer(&q->timer, jiffies + fqdir->timeout);
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*prev = rhashtable_lookup_get_insert_key(&fqdir->rhashtable, &q->key,
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&q->node, f->rhash_params);
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if (*prev) {
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q->flags |= INET_FRAG_COMPLETE;
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inet_frag_kill(q);
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inet_frag_destroy(q);
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return NULL;
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}
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return q;
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}
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/* TODO : call from rcu_read_lock() and no longer use refcount_inc_not_zero() */
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struct inet_frag_queue *inet_frag_find(struct fqdir *fqdir, void *key)
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{
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/* This pairs with WRITE_ONCE() in fqdir_pre_exit(). */
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long high_thresh = READ_ONCE(fqdir->high_thresh);
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struct inet_frag_queue *fq = NULL, *prev;
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if (!high_thresh || frag_mem_limit(fqdir) > high_thresh)
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return NULL;
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rcu_read_lock();
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prev = rhashtable_lookup(&fqdir->rhashtable, key, fqdir->f->rhash_params);
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if (!prev)
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fq = inet_frag_create(fqdir, key, &prev);
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if (!IS_ERR_OR_NULL(prev)) {
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fq = prev;
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if (!refcount_inc_not_zero(&fq->refcnt))
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fq = NULL;
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}
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rcu_read_unlock();
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return fq;
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}
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EXPORT_SYMBOL(inet_frag_find);
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int inet_frag_queue_insert(struct inet_frag_queue *q, struct sk_buff *skb,
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int offset, int end)
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{
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struct sk_buff *last = q->fragments_tail;
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/* RFC5722, Section 4, amended by Errata ID : 3089
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* When reassembling an IPv6 datagram, if
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* one or more its constituent fragments is determined to be an
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* overlapping fragment, the entire datagram (and any constituent
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* fragments) MUST be silently discarded.
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*
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* Duplicates, however, should be ignored (i.e. skb dropped, but the
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* queue/fragments kept for later reassembly).
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*/
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if (!last)
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fragrun_create(q, skb); /* First fragment. */
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else if (last->ip_defrag_offset + last->len < end) {
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/* This is the common case: skb goes to the end. */
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/* Detect and discard overlaps. */
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if (offset < last->ip_defrag_offset + last->len)
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return IPFRAG_OVERLAP;
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if (offset == last->ip_defrag_offset + last->len)
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fragrun_append_to_last(q, skb);
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else
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fragrun_create(q, skb);
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} else {
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/* Binary search. Note that skb can become the first fragment,
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* but not the last (covered above).
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*/
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struct rb_node **rbn, *parent;
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rbn = &q->rb_fragments.rb_node;
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do {
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struct sk_buff *curr;
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int curr_run_end;
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parent = *rbn;
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curr = rb_to_skb(parent);
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curr_run_end = curr->ip_defrag_offset +
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FRAG_CB(curr)->frag_run_len;
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if (end <= curr->ip_defrag_offset)
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rbn = &parent->rb_left;
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else if (offset >= curr_run_end)
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rbn = &parent->rb_right;
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else if (offset >= curr->ip_defrag_offset &&
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end <= curr_run_end)
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return IPFRAG_DUP;
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else
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return IPFRAG_OVERLAP;
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} while (*rbn);
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/* Here we have parent properly set, and rbn pointing to
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* one of its NULL left/right children. Insert skb.
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*/
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fragcb_clear(skb);
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rb_link_node(&skb->rbnode, parent, rbn);
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rb_insert_color(&skb->rbnode, &q->rb_fragments);
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}
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skb->ip_defrag_offset = offset;
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return IPFRAG_OK;
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}
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EXPORT_SYMBOL(inet_frag_queue_insert);
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void *inet_frag_reasm_prepare(struct inet_frag_queue *q, struct sk_buff *skb,
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struct sk_buff *parent)
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{
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struct sk_buff *fp, *head = skb_rb_first(&q->rb_fragments);
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struct sk_buff **nextp;
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int delta;
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if (head != skb) {
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fp = skb_clone(skb, GFP_ATOMIC);
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if (!fp)
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return NULL;
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FRAG_CB(fp)->next_frag = FRAG_CB(skb)->next_frag;
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if (RB_EMPTY_NODE(&skb->rbnode))
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FRAG_CB(parent)->next_frag = fp;
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else
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rb_replace_node(&skb->rbnode, &fp->rbnode,
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&q->rb_fragments);
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if (q->fragments_tail == skb)
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q->fragments_tail = fp;
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skb_morph(skb, head);
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FRAG_CB(skb)->next_frag = FRAG_CB(head)->next_frag;
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rb_replace_node(&head->rbnode, &skb->rbnode,
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&q->rb_fragments);
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consume_skb(head);
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head = skb;
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}
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WARN_ON(head->ip_defrag_offset != 0);
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delta = -head->truesize;
|
|
|
|
/* Head of list must not be cloned. */
|
|
if (skb_unclone(head, GFP_ATOMIC))
|
|
return NULL;
|
|
|
|
delta += head->truesize;
|
|
if (delta)
|
|
add_frag_mem_limit(q->fqdir, delta);
|
|
|
|
/* If the first fragment is fragmented itself, we split
|
|
* it to two chunks: the first with data and paged part
|
|
* and the second, holding only fragments.
|
|
*/
|
|
if (skb_has_frag_list(head)) {
|
|
struct sk_buff *clone;
|
|
int i, plen = 0;
|
|
|
|
clone = alloc_skb(0, GFP_ATOMIC);
|
|
if (!clone)
|
|
return NULL;
|
|
skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
|
|
skb_frag_list_init(head);
|
|
for (i = 0; i < skb_shinfo(head)->nr_frags; i++)
|
|
plen += skb_frag_size(&skb_shinfo(head)->frags[i]);
|
|
clone->data_len = head->data_len - plen;
|
|
clone->len = clone->data_len;
|
|
head->truesize += clone->truesize;
|
|
clone->csum = 0;
|
|
clone->ip_summed = head->ip_summed;
|
|
add_frag_mem_limit(q->fqdir, clone->truesize);
|
|
skb_shinfo(head)->frag_list = clone;
|
|
nextp = &clone->next;
|
|
} else {
|
|
nextp = &skb_shinfo(head)->frag_list;
|
|
}
|
|
|
|
return nextp;
|
|
}
|
|
EXPORT_SYMBOL(inet_frag_reasm_prepare);
|
|
|
|
void inet_frag_reasm_finish(struct inet_frag_queue *q, struct sk_buff *head,
|
|
void *reasm_data, bool try_coalesce)
|
|
{
|
|
struct sk_buff **nextp = reasm_data;
|
|
struct rb_node *rbn;
|
|
struct sk_buff *fp;
|
|
int sum_truesize;
|
|
|
|
skb_push(head, head->data - skb_network_header(head));
|
|
|
|
/* Traverse the tree in order, to build frag_list. */
|
|
fp = FRAG_CB(head)->next_frag;
|
|
rbn = rb_next(&head->rbnode);
|
|
rb_erase(&head->rbnode, &q->rb_fragments);
|
|
|
|
sum_truesize = head->truesize;
|
|
while (rbn || fp) {
|
|
/* fp points to the next sk_buff in the current run;
|
|
* rbn points to the next run.
|
|
*/
|
|
/* Go through the current run. */
|
|
while (fp) {
|
|
struct sk_buff *next_frag = FRAG_CB(fp)->next_frag;
|
|
bool stolen;
|
|
int delta;
|
|
|
|
sum_truesize += fp->truesize;
|
|
if (head->ip_summed != fp->ip_summed)
|
|
head->ip_summed = CHECKSUM_NONE;
|
|
else if (head->ip_summed == CHECKSUM_COMPLETE)
|
|
head->csum = csum_add(head->csum, fp->csum);
|
|
|
|
if (try_coalesce && skb_try_coalesce(head, fp, &stolen,
|
|
&delta)) {
|
|
kfree_skb_partial(fp, stolen);
|
|
} else {
|
|
fp->prev = NULL;
|
|
memset(&fp->rbnode, 0, sizeof(fp->rbnode));
|
|
fp->sk = NULL;
|
|
|
|
head->data_len += fp->len;
|
|
head->len += fp->len;
|
|
head->truesize += fp->truesize;
|
|
|
|
*nextp = fp;
|
|
nextp = &fp->next;
|
|
}
|
|
|
|
fp = next_frag;
|
|
}
|
|
/* Move to the next run. */
|
|
if (rbn) {
|
|
struct rb_node *rbnext = rb_next(rbn);
|
|
|
|
fp = rb_to_skb(rbn);
|
|
rb_erase(rbn, &q->rb_fragments);
|
|
rbn = rbnext;
|
|
}
|
|
}
|
|
sub_frag_mem_limit(q->fqdir, sum_truesize);
|
|
|
|
*nextp = NULL;
|
|
skb_mark_not_on_list(head);
|
|
head->prev = NULL;
|
|
head->tstamp = q->stamp;
|
|
head->mono_delivery_time = q->mono_delivery_time;
|
|
}
|
|
EXPORT_SYMBOL(inet_frag_reasm_finish);
|
|
|
|
struct sk_buff *inet_frag_pull_head(struct inet_frag_queue *q)
|
|
{
|
|
struct sk_buff *head, *skb;
|
|
|
|
head = skb_rb_first(&q->rb_fragments);
|
|
if (!head)
|
|
return NULL;
|
|
skb = FRAG_CB(head)->next_frag;
|
|
if (skb)
|
|
rb_replace_node(&head->rbnode, &skb->rbnode,
|
|
&q->rb_fragments);
|
|
else
|
|
rb_erase(&head->rbnode, &q->rb_fragments);
|
|
memset(&head->rbnode, 0, sizeof(head->rbnode));
|
|
barrier();
|
|
|
|
if (head == q->fragments_tail)
|
|
q->fragments_tail = NULL;
|
|
|
|
sub_frag_mem_limit(q->fqdir, head->truesize);
|
|
|
|
return head;
|
|
}
|
|
EXPORT_SYMBOL(inet_frag_pull_head);
|