// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* IPv6 fragment reassembly for connection tracking
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*
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* Copyright (C)2004 USAGI/WIDE Project
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*
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* Author:
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* Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
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*
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* Based on: net/ipv6/reassembly.c
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*/
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#define pr_fmt(fmt) "IPv6-nf: " fmt
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#include <linux/errno.h>
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#include <linux/types.h>
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#include <linux/string.h>
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#include <linux/socket.h>
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#include <linux/sockios.h>
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#include <linux/jiffies.h>
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#include <linux/net.h>
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#include <linux/list.h>
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#include <linux/netdevice.h>
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#include <linux/in6.h>
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#include <linux/ipv6.h>
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#include <linux/icmpv6.h>
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#include <linux/random.h>
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#include <linux/slab.h>
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#include <net/sock.h>
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#include <net/snmp.h>
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#include <net/ipv6_frag.h>
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#include <net/protocol.h>
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#include <net/transp_v6.h>
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#include <net/rawv6.h>
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#include <net/ndisc.h>
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#include <net/addrconf.h>
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#include <net/inet_ecn.h>
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#include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
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#include <linux/sysctl.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv6.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
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static const char nf_frags_cache_name[] = "nf-frags";
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static struct inet_frags nf_frags;
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#ifdef CONFIG_SYSCTL
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static struct ctl_table nf_ct_frag6_sysctl_table[] = {
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{
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.procname = "nf_conntrack_frag6_timeout",
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.maxlen = sizeof(unsigned int),
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.mode = 0644,
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.proc_handler = proc_dointvec_jiffies,
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},
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{
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.procname = "nf_conntrack_frag6_low_thresh",
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.maxlen = sizeof(unsigned long),
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.mode = 0644,
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.proc_handler = proc_doulongvec_minmax,
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},
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{
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.procname = "nf_conntrack_frag6_high_thresh",
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.maxlen = sizeof(unsigned long),
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.mode = 0644,
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.proc_handler = proc_doulongvec_minmax,
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},
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{ }
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};
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static int nf_ct_frag6_sysctl_register(struct net *net)
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{
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struct ctl_table *table;
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struct ctl_table_header *hdr;
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table = nf_ct_frag6_sysctl_table;
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if (!net_eq(net, &init_net)) {
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table = kmemdup(table, sizeof(nf_ct_frag6_sysctl_table),
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GFP_KERNEL);
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if (table == NULL)
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goto err_alloc;
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}
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table[0].data = &net->nf_frag.fqdir->timeout;
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table[1].data = &net->nf_frag.fqdir->low_thresh;
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table[1].extra2 = &net->nf_frag.fqdir->high_thresh;
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table[2].data = &net->nf_frag.fqdir->high_thresh;
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table[2].extra1 = &net->nf_frag.fqdir->low_thresh;
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table[2].extra2 = &init_net.nf_frag.fqdir->high_thresh;
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hdr = register_net_sysctl(net, "net/netfilter", table);
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if (hdr == NULL)
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goto err_reg;
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net->nf_frag_frags_hdr = hdr;
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return 0;
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err_reg:
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if (!net_eq(net, &init_net))
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kfree(table);
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err_alloc:
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return -ENOMEM;
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}
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static void __net_exit nf_ct_frags6_sysctl_unregister(struct net *net)
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{
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struct ctl_table *table;
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table = net->nf_frag_frags_hdr->ctl_table_arg;
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unregister_net_sysctl_table(net->nf_frag_frags_hdr);
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if (!net_eq(net, &init_net))
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kfree(table);
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}
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#else
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static int nf_ct_frag6_sysctl_register(struct net *net)
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{
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return 0;
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}
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static void __net_exit nf_ct_frags6_sysctl_unregister(struct net *net)
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{
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}
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#endif
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static int nf_ct_frag6_reasm(struct frag_queue *fq, struct sk_buff *skb,
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struct sk_buff *prev_tail, struct net_device *dev);
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static inline u8 ip6_frag_ecn(const struct ipv6hdr *ipv6h)
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{
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return 1 << (ipv6_get_dsfield(ipv6h) & INET_ECN_MASK);
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}
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static void nf_ct_frag6_expire(struct timer_list *t)
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{
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struct inet_frag_queue *frag = from_timer(frag, t, timer);
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struct frag_queue *fq;
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fq = container_of(frag, struct frag_queue, q);
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ip6frag_expire_frag_queue(fq->q.fqdir->net, fq);
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}
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/* Creation primitives. */
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static struct frag_queue *fq_find(struct net *net, __be32 id, u32 user,
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const struct ipv6hdr *hdr, int iif)
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{
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struct frag_v6_compare_key key = {
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.id = id,
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.saddr = hdr->saddr,
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.daddr = hdr->daddr,
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.user = user,
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.iif = iif,
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};
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struct inet_frag_queue *q;
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q = inet_frag_find(net->nf_frag.fqdir, &key);
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if (!q)
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return NULL;
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return container_of(q, struct frag_queue, q);
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}
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static int nf_ct_frag6_queue(struct frag_queue *fq, struct sk_buff *skb,
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const struct frag_hdr *fhdr, int nhoff)
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{
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unsigned int payload_len;
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struct net_device *dev;
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struct sk_buff *prev;
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int offset, end, err;
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u8 ecn;
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if (fq->q.flags & INET_FRAG_COMPLETE) {
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pr_debug("Already completed\n");
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goto err;
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}
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payload_len = ntohs(ipv6_hdr(skb)->payload_len);
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offset = ntohs(fhdr->frag_off) & ~0x7;
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end = offset + (payload_len -
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((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1)));
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if ((unsigned int)end > IPV6_MAXPLEN) {
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pr_debug("offset is too large.\n");
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return -EINVAL;
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}
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ecn = ip6_frag_ecn(ipv6_hdr(skb));
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if (skb->ip_summed == CHECKSUM_COMPLETE) {
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const unsigned char *nh = skb_network_header(skb);
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skb->csum = csum_sub(skb->csum,
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csum_partial(nh, (u8 *)(fhdr + 1) - nh,
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0));
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}
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/* Is this the final fragment? */
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if (!(fhdr->frag_off & htons(IP6_MF))) {
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/* If we already have some bits beyond end
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* or have different end, the segment is corrupted.
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*/
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if (end < fq->q.len ||
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((fq->q.flags & INET_FRAG_LAST_IN) && end != fq->q.len)) {
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pr_debug("already received last fragment\n");
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goto err;
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}
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fq->q.flags |= INET_FRAG_LAST_IN;
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fq->q.len = end;
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} else {
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/* Check if the fragment is rounded to 8 bytes.
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* Required by the RFC.
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*/
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if (end & 0x7) {
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/* RFC2460 says always send parameter problem in
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* this case. -DaveM
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*/
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pr_debug("end of fragment not rounded to 8 bytes.\n");
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inet_frag_kill(&fq->q);
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return -EPROTO;
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}
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if (end > fq->q.len) {
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/* Some bits beyond end -> corruption. */
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if (fq->q.flags & INET_FRAG_LAST_IN) {
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pr_debug("last packet already reached.\n");
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goto err;
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}
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fq->q.len = end;
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}
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}
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if (end == offset)
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goto err;
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/* Point into the IP datagram 'data' part. */
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if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data)) {
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pr_debug("queue: message is too short.\n");
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goto err;
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}
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if (pskb_trim_rcsum(skb, end - offset)) {
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pr_debug("Can't trim\n");
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goto err;
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}
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/* Note : skb->rbnode and skb->dev share the same location. */
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dev = skb->dev;
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/* Makes sure compiler wont do silly aliasing games */
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barrier();
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prev = fq->q.fragments_tail;
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err = inet_frag_queue_insert(&fq->q, skb, offset, end);
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if (err) {
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if (err == IPFRAG_DUP) {
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/* No error for duplicates, pretend they got queued. */
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kfree_skb(skb);
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return -EINPROGRESS;
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}
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goto insert_error;
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}
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if (dev)
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fq->iif = dev->ifindex;
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fq->q.stamp = skb->tstamp;
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fq->q.meat += skb->len;
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fq->ecn |= ecn;
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if (payload_len > fq->q.max_size)
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fq->q.max_size = payload_len;
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add_frag_mem_limit(fq->q.fqdir, skb->truesize);
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/* The first fragment.
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* nhoffset is obtained from the first fragment, of course.
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*/
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if (offset == 0) {
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fq->nhoffset = nhoff;
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fq->q.flags |= INET_FRAG_FIRST_IN;
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}
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if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
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fq->q.meat == fq->q.len) {
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unsigned long orefdst = skb->_skb_refdst;
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skb->_skb_refdst = 0UL;
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err = nf_ct_frag6_reasm(fq, skb, prev, dev);
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skb->_skb_refdst = orefdst;
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/* After queue has assumed skb ownership, only 0 or
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* -EINPROGRESS must be returned.
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*/
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return err ? -EINPROGRESS : 0;
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}
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skb_dst_drop(skb);
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return -EINPROGRESS;
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insert_error:
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inet_frag_kill(&fq->q);
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err:
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skb_dst_drop(skb);
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return -EINVAL;
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}
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/*
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* Check if this packet is complete.
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*
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* It is called with locked fq, and caller must check that
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* queue is eligible for reassembly i.e. it is not COMPLETE,
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* the last and the first frames arrived and all the bits are here.
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*/
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static int nf_ct_frag6_reasm(struct frag_queue *fq, struct sk_buff *skb,
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struct sk_buff *prev_tail, struct net_device *dev)
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{
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void *reasm_data;
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int payload_len;
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u8 ecn;
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inet_frag_kill(&fq->q);
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ecn = ip_frag_ecn_table[fq->ecn];
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if (unlikely(ecn == 0xff))
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goto err;
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reasm_data = inet_frag_reasm_prepare(&fq->q, skb, prev_tail);
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if (!reasm_data)
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goto err;
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payload_len = ((skb->data - skb_network_header(skb)) -
|
sizeof(struct ipv6hdr) + fq->q.len -
|
sizeof(struct frag_hdr));
|
if (payload_len > IPV6_MAXPLEN) {
|
net_dbg_ratelimited("nf_ct_frag6_reasm: payload len = %d\n",
|
payload_len);
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goto err;
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}
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/* We have to remove fragment header from datagram and to relocate
|
* header in order to calculate ICV correctly. */
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skb_network_header(skb)[fq->nhoffset] = skb_transport_header(skb)[0];
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memmove(skb->head + sizeof(struct frag_hdr), skb->head,
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(skb->data - skb->head) - sizeof(struct frag_hdr));
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skb->mac_header += sizeof(struct frag_hdr);
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skb->network_header += sizeof(struct frag_hdr);
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|
skb_reset_transport_header(skb);
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inet_frag_reasm_finish(&fq->q, skb, reasm_data, false);
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skb->ignore_df = 1;
|
skb->dev = dev;
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ipv6_hdr(skb)->payload_len = htons(payload_len);
|
ipv6_change_dsfield(ipv6_hdr(skb), 0xff, ecn);
|
IP6CB(skb)->frag_max_size = sizeof(struct ipv6hdr) + fq->q.max_size;
|
IP6CB(skb)->flags |= IP6SKB_FRAGMENTED;
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|
/* Yes, and fold redundant checksum back. 8) */
|
if (skb->ip_summed == CHECKSUM_COMPLETE)
|
skb->csum = csum_partial(skb_network_header(skb),
|
skb_network_header_len(skb),
|
skb->csum);
|
|
fq->q.rb_fragments = RB_ROOT;
|
fq->q.fragments_tail = NULL;
|
fq->q.last_run_head = NULL;
|
|
return 0;
|
|
err:
|
inet_frag_kill(&fq->q);
|
return -EINVAL;
|
}
|
|
/*
|
* find the header just before Fragment Header.
|
*
|
* if success return 0 and set ...
|
* (*prevhdrp): the value of "Next Header Field" in the header
|
* just before Fragment Header.
|
* (*prevhoff): the offset of "Next Header Field" in the header
|
* just before Fragment Header.
|
* (*fhoff) : the offset of Fragment Header.
|
*
|
* Based on ipv6_skip_hdr() in net/ipv6/exthdr.c
|
*
|
*/
|
static int
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find_prev_fhdr(struct sk_buff *skb, u8 *prevhdrp, int *prevhoff, int *fhoff)
|
{
|
u8 nexthdr = ipv6_hdr(skb)->nexthdr;
|
const int netoff = skb_network_offset(skb);
|
u8 prev_nhoff = netoff + offsetof(struct ipv6hdr, nexthdr);
|
int start = netoff + sizeof(struct ipv6hdr);
|
int len = skb->len - start;
|
u8 prevhdr = NEXTHDR_IPV6;
|
|
while (nexthdr != NEXTHDR_FRAGMENT) {
|
struct ipv6_opt_hdr hdr;
|
int hdrlen;
|
|
if (!ipv6_ext_hdr(nexthdr)) {
|
return -1;
|
}
|
if (nexthdr == NEXTHDR_NONE) {
|
pr_debug("next header is none\n");
|
return -1;
|
}
|
if (len < (int)sizeof(struct ipv6_opt_hdr)) {
|
pr_debug("too short\n");
|
return -1;
|
}
|
if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
|
BUG();
|
if (nexthdr == NEXTHDR_AUTH)
|
hdrlen = ipv6_authlen(&hdr);
|
else
|
hdrlen = ipv6_optlen(&hdr);
|
|
prevhdr = nexthdr;
|
prev_nhoff = start;
|
|
nexthdr = hdr.nexthdr;
|
len -= hdrlen;
|
start += hdrlen;
|
}
|
|
if (len < 0)
|
return -1;
|
|
*prevhdrp = prevhdr;
|
*prevhoff = prev_nhoff;
|
*fhoff = start;
|
|
return 0;
|
}
|
|
int nf_ct_frag6_gather(struct net *net, struct sk_buff *skb, u32 user)
|
{
|
u16 savethdr = skb->transport_header;
|
u8 nexthdr = NEXTHDR_FRAGMENT;
|
int fhoff, nhoff, ret;
|
struct frag_hdr *fhdr;
|
struct frag_queue *fq;
|
struct ipv6hdr *hdr;
|
u8 prevhdr;
|
|
/* Jumbo payload inhibits frag. header */
|
if (ipv6_hdr(skb)->payload_len == 0) {
|
pr_debug("payload len = 0\n");
|
return 0;
|
}
|
|
if (find_prev_fhdr(skb, &prevhdr, &nhoff, &fhoff) < 0)
|
return 0;
|
|
/* Discard the first fragment if it does not include all headers
|
* RFC 8200, Section 4.5
|
*/
|
if (ipv6frag_thdr_truncated(skb, fhoff, &nexthdr)) {
|
pr_debug("Drop incomplete fragment\n");
|
return 0;
|
}
|
|
if (!pskb_may_pull(skb, fhoff + sizeof(*fhdr)))
|
return -ENOMEM;
|
|
skb_set_transport_header(skb, fhoff);
|
hdr = ipv6_hdr(skb);
|
fhdr = (struct frag_hdr *)skb_transport_header(skb);
|
|
skb_orphan(skb);
|
fq = fq_find(net, fhdr->identification, user, hdr,
|
skb->dev ? skb->dev->ifindex : 0);
|
if (fq == NULL) {
|
pr_debug("Can't find and can't create new queue\n");
|
return -ENOMEM;
|
}
|
|
spin_lock_bh(&fq->q.lock);
|
|
ret = nf_ct_frag6_queue(fq, skb, fhdr, nhoff);
|
if (ret == -EPROTO) {
|
skb->transport_header = savethdr;
|
ret = 0;
|
}
|
|
spin_unlock_bh(&fq->q.lock);
|
inet_frag_put(&fq->q);
|
return ret;
|
}
|
EXPORT_SYMBOL_GPL(nf_ct_frag6_gather);
|
|
static int nf_ct_net_init(struct net *net)
|
{
|
int res;
|
|
res = fqdir_init(&net->nf_frag.fqdir, &nf_frags, net);
|
if (res < 0)
|
return res;
|
|
net->nf_frag.fqdir->high_thresh = IPV6_FRAG_HIGH_THRESH;
|
net->nf_frag.fqdir->low_thresh = IPV6_FRAG_LOW_THRESH;
|
net->nf_frag.fqdir->timeout = IPV6_FRAG_TIMEOUT;
|
|
res = nf_ct_frag6_sysctl_register(net);
|
if (res < 0)
|
fqdir_exit(net->nf_frag.fqdir);
|
return res;
|
}
|
|
static void nf_ct_net_pre_exit(struct net *net)
|
{
|
fqdir_pre_exit(net->nf_frag.fqdir);
|
}
|
|
static void nf_ct_net_exit(struct net *net)
|
{
|
nf_ct_frags6_sysctl_unregister(net);
|
fqdir_exit(net->nf_frag.fqdir);
|
}
|
|
static struct pernet_operations nf_ct_net_ops = {
|
.init = nf_ct_net_init,
|
.pre_exit = nf_ct_net_pre_exit,
|
.exit = nf_ct_net_exit,
|
};
|
|
static const struct rhashtable_params nfct_rhash_params = {
|
.head_offset = offsetof(struct inet_frag_queue, node),
|
.hashfn = ip6frag_key_hashfn,
|
.obj_hashfn = ip6frag_obj_hashfn,
|
.obj_cmpfn = ip6frag_obj_cmpfn,
|
.automatic_shrinking = true,
|
};
|
|
int nf_ct_frag6_init(void)
|
{
|
int ret = 0;
|
|
nf_frags.constructor = ip6frag_init;
|
nf_frags.destructor = NULL;
|
nf_frags.qsize = sizeof(struct frag_queue);
|
nf_frags.frag_expire = nf_ct_frag6_expire;
|
nf_frags.frags_cache_name = nf_frags_cache_name;
|
nf_frags.rhash_params = nfct_rhash_params;
|
ret = inet_frags_init(&nf_frags);
|
if (ret)
|
goto out;
|
ret = register_pernet_subsys(&nf_ct_net_ops);
|
if (ret)
|
inet_frags_fini(&nf_frags);
|
|
out:
|
return ret;
|
}
|
|
void nf_ct_frag6_cleanup(void)
|
{
|
unregister_pernet_subsys(&nf_ct_net_ops);
|
inet_frags_fini(&nf_frags);
|
}
|
