![Ilpo Järvinen](/assets/img/avatar_default.png)
Removes legacy reinvent-the-wheel type thing. The generic machinery integrates much better to automated debugging aids such as kerneloops.org (and others), and is unambiguous due to better naming. Non-intuively BUG_TRAP() is actually equal to WARN_ON() rather than BUG_ON() though some might actually be promoted to BUG_ON() but I left that to future. I could make at least one BUILD_BUG_ON conversion. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
716 lines
17 KiB
C
716 lines
17 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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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/jhash.h>
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#include <net/sock.h>
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#include <net/snmp.h>
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#include <net/inet_frag.h>
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#include <net/ipv6.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/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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#define NF_CT_FRAG6_HIGH_THRESH 262144 /* == 256*1024 */
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#define NF_CT_FRAG6_LOW_THRESH 196608 /* == 192*1024 */
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#define NF_CT_FRAG6_TIMEOUT IPV6_FRAG_TIMEOUT
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struct nf_ct_frag6_skb_cb
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{
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struct inet6_skb_parm h;
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int offset;
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struct sk_buff *orig;
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};
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#define NFCT_FRAG6_CB(skb) ((struct nf_ct_frag6_skb_cb*)((skb)->cb))
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struct nf_ct_frag6_queue
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{
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struct inet_frag_queue q;
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__be32 id; /* fragment id */
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struct in6_addr saddr;
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struct in6_addr daddr;
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unsigned int csum;
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__u16 nhoffset;
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};
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static struct inet_frags nf_frags;
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static struct netns_frags nf_init_frags;
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#ifdef CONFIG_SYSCTL
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struct ctl_table nf_ct_ipv6_sysctl_table[] = {
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{
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.procname = "nf_conntrack_frag6_timeout",
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.data = &nf_init_frags.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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.ctl_name = NET_NF_CONNTRACK_FRAG6_LOW_THRESH,
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.procname = "nf_conntrack_frag6_low_thresh",
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.data = &nf_init_frags.low_thresh,
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.maxlen = sizeof(unsigned int),
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.mode = 0644,
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.proc_handler = &proc_dointvec,
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},
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{
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.ctl_name = NET_NF_CONNTRACK_FRAG6_HIGH_THRESH,
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.procname = "nf_conntrack_frag6_high_thresh",
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.data = &nf_init_frags.high_thresh,
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.maxlen = sizeof(unsigned int),
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.mode = 0644,
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.proc_handler = &proc_dointvec,
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},
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{ .ctl_name = 0 }
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};
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#endif
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static unsigned int ip6qhashfn(__be32 id, const struct in6_addr *saddr,
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const struct in6_addr *daddr)
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{
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u32 a, b, c;
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a = (__force u32)saddr->s6_addr32[0];
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b = (__force u32)saddr->s6_addr32[1];
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c = (__force u32)saddr->s6_addr32[2];
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a += JHASH_GOLDEN_RATIO;
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b += JHASH_GOLDEN_RATIO;
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c += nf_frags.rnd;
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__jhash_mix(a, b, c);
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a += (__force u32)saddr->s6_addr32[3];
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b += (__force u32)daddr->s6_addr32[0];
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c += (__force u32)daddr->s6_addr32[1];
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__jhash_mix(a, b, c);
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a += (__force u32)daddr->s6_addr32[2];
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b += (__force u32)daddr->s6_addr32[3];
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c += (__force u32)id;
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__jhash_mix(a, b, c);
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return c & (INETFRAGS_HASHSZ - 1);
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}
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static unsigned int nf_hashfn(struct inet_frag_queue *q)
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{
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const struct nf_ct_frag6_queue *nq;
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nq = container_of(q, struct nf_ct_frag6_queue, q);
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return ip6qhashfn(nq->id, &nq->saddr, &nq->daddr);
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}
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static void nf_skb_free(struct sk_buff *skb)
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{
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if (NFCT_FRAG6_CB(skb)->orig)
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kfree_skb(NFCT_FRAG6_CB(skb)->orig);
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}
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/* Memory Tracking Functions. */
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static inline void frag_kfree_skb(struct sk_buff *skb, unsigned int *work)
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{
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if (work)
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*work -= skb->truesize;
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atomic_sub(skb->truesize, &nf_init_frags.mem);
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nf_skb_free(skb);
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kfree_skb(skb);
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}
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/* Destruction primitives. */
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static __inline__ void fq_put(struct nf_ct_frag6_queue *fq)
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{
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inet_frag_put(&fq->q, &nf_frags);
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}
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/* Kill fq entry. It is not destroyed immediately,
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* because caller (and someone more) holds reference count.
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*/
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static __inline__ void fq_kill(struct nf_ct_frag6_queue *fq)
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{
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inet_frag_kill(&fq->q, &nf_frags);
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}
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static void nf_ct_frag6_evictor(void)
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{
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local_bh_disable();
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inet_frag_evictor(&nf_init_frags, &nf_frags);
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local_bh_enable();
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}
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static void nf_ct_frag6_expire(unsigned long data)
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{
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struct nf_ct_frag6_queue *fq;
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fq = container_of((struct inet_frag_queue *)data,
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struct nf_ct_frag6_queue, q);
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spin_lock(&fq->q.lock);
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if (fq->q.last_in & INET_FRAG_COMPLETE)
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goto out;
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fq_kill(fq);
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out:
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spin_unlock(&fq->q.lock);
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fq_put(fq);
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}
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/* Creation primitives. */
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static __inline__ struct nf_ct_frag6_queue *
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fq_find(__be32 id, struct in6_addr *src, struct in6_addr *dst)
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{
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struct inet_frag_queue *q;
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struct ip6_create_arg arg;
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unsigned int hash;
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arg.id = id;
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arg.src = src;
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arg.dst = dst;
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read_lock_bh(&nf_frags.lock);
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hash = ip6qhashfn(id, src, dst);
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q = inet_frag_find(&nf_init_frags, &nf_frags, &arg, hash);
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local_bh_enable();
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if (q == NULL)
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goto oom;
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return container_of(q, struct nf_ct_frag6_queue, q);
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oom:
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pr_debug("Can't alloc new queue\n");
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return NULL;
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}
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static int nf_ct_frag6_queue(struct nf_ct_frag6_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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struct sk_buff *prev, *next;
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int offset, end;
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if (fq->q.last_in & INET_FRAG_COMPLETE) {
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pr_debug("Allready completed\n");
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goto err;
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}
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offset = ntohs(fhdr->frag_off) & ~0x7;
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end = offset + (ntohs(ipv6_hdr(skb)->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 -1;
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}
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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.last_in & 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.last_in |= 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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return -1;
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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.last_in & 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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/* Find out which fragments are in front and at the back of us
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* in the chain of fragments so far. We must know where to put
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* this fragment, right?
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*/
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prev = NULL;
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for (next = fq->q.fragments; next != NULL; next = next->next) {
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if (NFCT_FRAG6_CB(next)->offset >= offset)
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break; /* bingo! */
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prev = next;
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}
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/* We found where to put this one. Check for overlap with
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* preceding fragment, and, if needed, align things so that
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* any overlaps are eliminated.
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*/
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if (prev) {
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int i = (NFCT_FRAG6_CB(prev)->offset + prev->len) - offset;
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if (i > 0) {
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offset += i;
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if (end <= offset) {
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pr_debug("overlap\n");
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goto err;
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}
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if (!pskb_pull(skb, i)) {
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pr_debug("Can't pull\n");
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goto err;
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}
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if (skb->ip_summed != CHECKSUM_UNNECESSARY)
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skb->ip_summed = CHECKSUM_NONE;
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}
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}
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/* Look for overlap with succeeding segments.
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* If we can merge fragments, do it.
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*/
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while (next && NFCT_FRAG6_CB(next)->offset < end) {
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/* overlap is 'i' bytes */
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int i = end - NFCT_FRAG6_CB(next)->offset;
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if (i < next->len) {
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/* Eat head of the next overlapped fragment
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* and leave the loop. The next ones cannot overlap.
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*/
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pr_debug("Eat head of the overlapped parts.: %d", i);
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if (!pskb_pull(next, i))
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goto err;
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/* next fragment */
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NFCT_FRAG6_CB(next)->offset += i;
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fq->q.meat -= i;
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if (next->ip_summed != CHECKSUM_UNNECESSARY)
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next->ip_summed = CHECKSUM_NONE;
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break;
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} else {
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struct sk_buff *free_it = next;
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/* Old fragmnet is completely overridden with
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* new one drop it.
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*/
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next = next->next;
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if (prev)
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prev->next = next;
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else
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fq->q.fragments = next;
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fq->q.meat -= free_it->len;
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frag_kfree_skb(free_it, NULL);
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}
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}
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NFCT_FRAG6_CB(skb)->offset = offset;
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/* Insert this fragment in the chain of fragments. */
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skb->next = next;
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if (prev)
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prev->next = skb;
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else
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fq->q.fragments = skb;
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skb->dev = NULL;
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fq->q.stamp = skb->tstamp;
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fq->q.meat += skb->len;
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atomic_add(skb->truesize, &nf_init_frags.mem);
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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.last_in |= INET_FRAG_FIRST_IN;
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}
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write_lock(&nf_frags.lock);
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list_move_tail(&fq->q.lru_list, &nf_init_frags.lru_list);
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write_unlock(&nf_frags.lock);
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return 0;
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err:
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return -1;
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}
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/*
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* Check if this packet is complete.
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* Returns NULL on failure by any reason, and pointer
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* to current nexthdr field in reassembled frame.
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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 struct sk_buff *
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nf_ct_frag6_reasm(struct nf_ct_frag6_queue *fq, struct net_device *dev)
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{
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struct sk_buff *fp, *op, *head = fq->q.fragments;
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int payload_len;
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fq_kill(fq);
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WARN_ON(head == NULL);
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WARN_ON(NFCT_FRAG6_CB(head)->offset != 0);
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/* Unfragmented part is taken from the first segment. */
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payload_len = ((head->data - skb_network_header(head)) -
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sizeof(struct ipv6hdr) + fq->q.len -
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sizeof(struct frag_hdr));
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if (payload_len > IPV6_MAXPLEN) {
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pr_debug("payload len is too large.\n");
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goto out_oversize;
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}
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/* Head of list must not be cloned. */
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if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) {
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pr_debug("skb is cloned but can't expand head");
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goto out_oom;
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}
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/* If the first fragment is fragmented itself, we split
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* it to two chunks: the first with data and paged part
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* and the second, holding only fragments. */
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if (skb_shinfo(head)->frag_list) {
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struct sk_buff *clone;
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int i, plen = 0;
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if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) {
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pr_debug("Can't alloc skb\n");
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goto out_oom;
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}
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clone->next = head->next;
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head->next = clone;
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skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
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skb_shinfo(head)->frag_list = NULL;
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for (i=0; i<skb_shinfo(head)->nr_frags; i++)
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plen += skb_shinfo(head)->frags[i].size;
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clone->len = clone->data_len = head->data_len - plen;
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head->data_len -= clone->len;
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head->len -= clone->len;
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clone->csum = 0;
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clone->ip_summed = head->ip_summed;
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NFCT_FRAG6_CB(clone)->orig = NULL;
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atomic_add(clone->truesize, &nf_init_frags.mem);
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}
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/* We have to remove fragment header from datagram and to relocate
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* header in order to calculate ICV correctly. */
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skb_network_header(head)[fq->nhoffset] = skb_transport_header(head)[0];
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memmove(head->head + sizeof(struct frag_hdr), head->head,
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(head->data - head->head) - sizeof(struct frag_hdr));
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head->mac_header += sizeof(struct frag_hdr);
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head->network_header += sizeof(struct frag_hdr);
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skb_shinfo(head)->frag_list = head->next;
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skb_reset_transport_header(head);
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skb_push(head, head->data - skb_network_header(head));
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atomic_sub(head->truesize, &nf_init_frags.mem);
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for (fp=head->next; fp; fp = fp->next) {
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head->data_len += fp->len;
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head->len += fp->len;
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if (head->ip_summed != fp->ip_summed)
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head->ip_summed = CHECKSUM_NONE;
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else if (head->ip_summed == CHECKSUM_COMPLETE)
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head->csum = csum_add(head->csum, fp->csum);
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head->truesize += fp->truesize;
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atomic_sub(fp->truesize, &nf_init_frags.mem);
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}
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head->next = NULL;
|
|
head->dev = dev;
|
|
head->tstamp = fq->q.stamp;
|
|
ipv6_hdr(head)->payload_len = htons(payload_len);
|
|
|
|
/* Yes, and fold redundant checksum back. 8) */
|
|
if (head->ip_summed == CHECKSUM_COMPLETE)
|
|
head->csum = csum_partial(skb_network_header(head),
|
|
skb_network_header_len(head),
|
|
head->csum);
|
|
|
|
fq->q.fragments = NULL;
|
|
|
|
/* all original skbs are linked into the NFCT_FRAG6_CB(head).orig */
|
|
fp = skb_shinfo(head)->frag_list;
|
|
if (NFCT_FRAG6_CB(fp)->orig == NULL)
|
|
/* at above code, head skb is divided into two skbs. */
|
|
fp = fp->next;
|
|
|
|
op = NFCT_FRAG6_CB(head)->orig;
|
|
for (; fp; fp = fp->next) {
|
|
struct sk_buff *orig = NFCT_FRAG6_CB(fp)->orig;
|
|
|
|
op->next = orig;
|
|
op = orig;
|
|
NFCT_FRAG6_CB(fp)->orig = NULL;
|
|
}
|
|
|
|
return head;
|
|
|
|
out_oversize:
|
|
if (net_ratelimit())
|
|
printk(KERN_DEBUG "nf_ct_frag6_reasm: payload len = %d\n", payload_len);
|
|
goto out_fail;
|
|
out_oom:
|
|
if (net_ratelimit())
|
|
printk(KERN_DEBUG "nf_ct_frag6_reasm: no memory for reassembly\n");
|
|
out_fail:
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* 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
|
|
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 (len < (int)sizeof(struct ipv6_opt_hdr)) {
|
|
pr_debug("too short\n");
|
|
return -1;
|
|
}
|
|
if (nexthdr == NEXTHDR_NONE) {
|
|
pr_debug("next header is none\n");
|
|
return -1;
|
|
}
|
|
if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
|
|
BUG();
|
|
if (nexthdr == NEXTHDR_AUTH)
|
|
hdrlen = (hdr.hdrlen+2)<<2;
|
|
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;
|
|
}
|
|
|
|
struct sk_buff *nf_ct_frag6_gather(struct sk_buff *skb)
|
|
{
|
|
struct sk_buff *clone;
|
|
struct net_device *dev = skb->dev;
|
|
struct frag_hdr *fhdr;
|
|
struct nf_ct_frag6_queue *fq;
|
|
struct ipv6hdr *hdr;
|
|
int fhoff, nhoff;
|
|
u8 prevhdr;
|
|
struct sk_buff *ret_skb = NULL;
|
|
|
|
/* Jumbo payload inhibits frag. header */
|
|
if (ipv6_hdr(skb)->payload_len == 0) {
|
|
pr_debug("payload len = 0\n");
|
|
return skb;
|
|
}
|
|
|
|
if (find_prev_fhdr(skb, &prevhdr, &nhoff, &fhoff) < 0)
|
|
return skb;
|
|
|
|
clone = skb_clone(skb, GFP_ATOMIC);
|
|
if (clone == NULL) {
|
|
pr_debug("Can't clone skb\n");
|
|
return skb;
|
|
}
|
|
|
|
NFCT_FRAG6_CB(clone)->orig = skb;
|
|
|
|
if (!pskb_may_pull(clone, fhoff + sizeof(*fhdr))) {
|
|
pr_debug("message is too short.\n");
|
|
goto ret_orig;
|
|
}
|
|
|
|
skb_set_transport_header(clone, fhoff);
|
|
hdr = ipv6_hdr(clone);
|
|
fhdr = (struct frag_hdr *)skb_transport_header(clone);
|
|
|
|
if (!(fhdr->frag_off & htons(0xFFF9))) {
|
|
pr_debug("Invalid fragment offset\n");
|
|
/* It is not a fragmented frame */
|
|
goto ret_orig;
|
|
}
|
|
|
|
if (atomic_read(&nf_init_frags.mem) > nf_init_frags.high_thresh)
|
|
nf_ct_frag6_evictor();
|
|
|
|
fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr);
|
|
if (fq == NULL) {
|
|
pr_debug("Can't find and can't create new queue\n");
|
|
goto ret_orig;
|
|
}
|
|
|
|
spin_lock_bh(&fq->q.lock);
|
|
|
|
if (nf_ct_frag6_queue(fq, clone, fhdr, nhoff) < 0) {
|
|
spin_unlock_bh(&fq->q.lock);
|
|
pr_debug("Can't insert skb to queue\n");
|
|
fq_put(fq);
|
|
goto ret_orig;
|
|
}
|
|
|
|
if (fq->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
|
|
fq->q.meat == fq->q.len) {
|
|
ret_skb = nf_ct_frag6_reasm(fq, dev);
|
|
if (ret_skb == NULL)
|
|
pr_debug("Can't reassemble fragmented packets\n");
|
|
}
|
|
spin_unlock_bh(&fq->q.lock);
|
|
|
|
fq_put(fq);
|
|
return ret_skb;
|
|
|
|
ret_orig:
|
|
kfree_skb(clone);
|
|
return skb;
|
|
}
|
|
|
|
void nf_ct_frag6_output(unsigned int hooknum, struct sk_buff *skb,
|
|
struct net_device *in, struct net_device *out,
|
|
int (*okfn)(struct sk_buff *))
|
|
{
|
|
struct sk_buff *s, *s2;
|
|
|
|
for (s = NFCT_FRAG6_CB(skb)->orig; s;) {
|
|
nf_conntrack_put_reasm(s->nfct_reasm);
|
|
nf_conntrack_get_reasm(skb);
|
|
s->nfct_reasm = skb;
|
|
|
|
s2 = s->next;
|
|
s->next = NULL;
|
|
|
|
NF_HOOK_THRESH(PF_INET6, hooknum, s, in, out, okfn,
|
|
NF_IP6_PRI_CONNTRACK_DEFRAG + 1);
|
|
s = s2;
|
|
}
|
|
nf_conntrack_put_reasm(skb);
|
|
}
|
|
|
|
int nf_ct_frag6_init(void)
|
|
{
|
|
nf_frags.hashfn = nf_hashfn;
|
|
nf_frags.constructor = ip6_frag_init;
|
|
nf_frags.destructor = NULL;
|
|
nf_frags.skb_free = nf_skb_free;
|
|
nf_frags.qsize = sizeof(struct nf_ct_frag6_queue);
|
|
nf_frags.match = ip6_frag_match;
|
|
nf_frags.frag_expire = nf_ct_frag6_expire;
|
|
nf_frags.secret_interval = 10 * 60 * HZ;
|
|
nf_init_frags.timeout = IPV6_FRAG_TIMEOUT;
|
|
nf_init_frags.high_thresh = 256 * 1024;
|
|
nf_init_frags.low_thresh = 192 * 1024;
|
|
inet_frags_init_net(&nf_init_frags);
|
|
inet_frags_init(&nf_frags);
|
|
|
|
return 0;
|
|
}
|
|
|
|
void nf_ct_frag6_cleanup(void)
|
|
{
|
|
inet_frags_fini(&nf_frags);
|
|
|
|
nf_init_frags.low_thresh = 0;
|
|
nf_ct_frag6_evictor();
|
|
}
|