1 files changed, 651 insertions, 0 deletions

diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
new file mode 100644
index 00000000..08572726
--- /dev/null
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -0,0 +1,651 @@
+/*
+ * IPv6 fragment reassembly for connection tracking
+ *
+ * Copyright (C)2004 USAGI/WIDE Project
+ *
+ * Author:
+ *	Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
+ *
+ * Based on: net/ipv6/reassembly.c
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/socket.h>
+#include <linux/sockios.h>
+#include <linux/jiffies.h>
+#include <linux/net.h>
+#include <linux/list.h>
+#include <linux/netdevice.h>
+#include <linux/in6.h>
+#include <linux/ipv6.h>
+#include <linux/icmpv6.h>
+#include <linux/random.h>
+#include <linux/slab.h>
+
+#include <net/sock.h>
+#include <net/snmp.h>
+#include <net/inet_frag.h>
+
+#include <net/ipv6.h>
+#include <net/protocol.h>
+#include <net/transp_v6.h>
+#include <net/rawv6.h>
+#include <net/ndisc.h>
+#include <net/addrconf.h>
+#include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
+#include <linux/sysctl.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv6.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
+
+
+struct nf_ct_frag6_skb_cb
+{
+	struct inet6_skb_parm	h;
+	int			offset;
+	struct sk_buff		*orig;
+};
+
+#define NFCT_FRAG6_CB(skb)	((struct nf_ct_frag6_skb_cb*)((skb)->cb))
+
+struct nf_ct_frag6_queue
+{
+	struct inet_frag_queue	q;
+
+	__be32			id;		/* fragment id		*/
+	u32			user;
+	struct in6_addr		saddr;
+	struct in6_addr		daddr;
+
+	unsigned int		csum;
+	__u16			nhoffset;
+};
+
+static struct inet_frags nf_frags;
+static struct netns_frags nf_init_frags;
+
+#ifdef CONFIG_SYSCTL
+static struct ctl_table nf_ct_frag6_sysctl_table[] = {
+	{
+		.procname	= "nf_conntrack_frag6_timeout",
+		.data		= &nf_init_frags.timeout,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{
+		.procname	= "nf_conntrack_frag6_low_thresh",
+		.data		= &nf_init_frags.low_thresh,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "nf_conntrack_frag6_high_thresh",
+		.data		= &nf_init_frags.high_thresh,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{ }
+};
+
+static struct ctl_table_header *nf_ct_frag6_sysctl_header;
+#endif
+
+static unsigned int nf_hashfn(struct inet_frag_queue *q)
+{
+	const struct nf_ct_frag6_queue *nq;
+
+	nq = container_of(q, struct nf_ct_frag6_queue, q);
+	return inet6_hash_frag(nq->id, &nq->saddr, &nq->daddr, nf_frags.rnd);
+}
+
+static void nf_skb_free(struct sk_buff *skb)
+{
+	if (NFCT_FRAG6_CB(skb)->orig)
+		kfree_skb(NFCT_FRAG6_CB(skb)->orig);
+}
+
+/* Destruction primitives. */
+
+static __inline__ void fq_put(struct nf_ct_frag6_queue *fq)
+{
+	inet_frag_put(&fq->q, &nf_frags);
+}
+
+/* Kill fq entry. It is not destroyed immediately,
+ * because caller (and someone more) holds reference count.
+ */
+static __inline__ void fq_kill(struct nf_ct_frag6_queue *fq)
+{
+	inet_frag_kill(&fq->q, &nf_frags);
+}
+
+static void nf_ct_frag6_evictor(void)
+{
+	local_bh_disable();
+	inet_frag_evictor(&nf_init_frags, &nf_frags);
+	local_bh_enable();
+}
+
+static void nf_ct_frag6_expire(unsigned long data)
+{
+	struct nf_ct_frag6_queue *fq;
+
+	fq = container_of((struct inet_frag_queue *)data,
+			struct nf_ct_frag6_queue, q);
+
+	spin_lock(&fq->q.lock);
+
+	if (fq->q.last_in & INET_FRAG_COMPLETE)
+		goto out;
+
+	fq_kill(fq);
+
+out:
+	spin_unlock(&fq->q.lock);
+	fq_put(fq);
+}
+
+/* Creation primitives. */
+
+static __inline__ struct nf_ct_frag6_queue *
+fq_find(__be32 id, u32 user, struct in6_addr *src, struct in6_addr *dst)
+{
+	struct inet_frag_queue *q;
+	struct ip6_create_arg arg;
+	unsigned int hash;
+
+	arg.id = id;
+	arg.user = user;
+	arg.src = src;
+	arg.dst = dst;
+
+	read_lock_bh(&nf_frags.lock);
+	hash = inet6_hash_frag(id, src, dst, nf_frags.rnd);
+
+	q = inet_frag_find(&nf_init_frags, &nf_frags, &arg, hash);
+	local_bh_enable();
+	if (q == NULL)
+		goto oom;
+
+	return container_of(q, struct nf_ct_frag6_queue, q);
+
+oom:
+	pr_debug("Can't alloc new queue\n");
+	return NULL;
+}
+
+
+static int nf_ct_frag6_queue(struct nf_ct_frag6_queue *fq, struct sk_buff *skb,
+			     const struct frag_hdr *fhdr, int nhoff)
+{
+	struct sk_buff *prev, *next;
+	int offset, end;
+
+	if (fq->q.last_in & INET_FRAG_COMPLETE) {
+		pr_debug("Already completed\n");
+		goto err;
+	}
+
+	offset = ntohs(fhdr->frag_off) & ~0x7;
+	end = offset + (ntohs(ipv6_hdr(skb)->payload_len) -
+			((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1)));
+
+	if ((unsigned int)end > IPV6_MAXPLEN) {
+		pr_debug("offset is too large.\n");
+		return -1;
+	}
+
+	if (skb->ip_summed == CHECKSUM_COMPLETE) {
+		const unsigned char *nh = skb_network_header(skb);
+		skb->csum = csum_sub(skb->csum,
+				     csum_partial(nh, (u8 *)(fhdr + 1) - nh,
+						  0));
+	}
+
+	/* Is this the final fragment? */
+	if (!(fhdr->frag_off & htons(IP6_MF))) {
+		/* If we already have some bits beyond end
+		 * or have different end, the segment is corrupted.
+		 */
+		if (end < fq->q.len ||
+		    ((fq->q.last_in & INET_FRAG_LAST_IN) && end != fq->q.len)) {
+			pr_debug("already received last fragment\n");
+			goto err;
+		}
+		fq->q.last_in |= INET_FRAG_LAST_IN;
+		fq->q.len = end;
+	} else {
+		/* Check if the fragment is rounded to 8 bytes.
+		 * Required by the RFC.
+		 */
+		if (end & 0x7) {
+			/* RFC2460 says always send parameter problem in
+			 * this case. -DaveM
+			 */
+			pr_debug("end of fragment not rounded to 8 bytes.\n");
+			return -1;
+		}
+		if (end > fq->q.len) {
+			/* Some bits beyond end -> corruption. */
+			if (fq->q.last_in & INET_FRAG_LAST_IN) {
+				pr_debug("last packet already reached.\n");
+				goto err;
+			}
+			fq->q.len = end;
+		}
+	}
+
+	if (end == offset)
+		goto err;
+
+	/* Point into the IP datagram 'data' part. */
+	if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data)) {
+		pr_debug("queue: message is too short.\n");
+		goto err;
+	}
+	if (pskb_trim_rcsum(skb, end - offset)) {
+		pr_debug("Can't trim\n");
+		goto err;
+	}
+
+	/* Find out which fragments are in front and at the back of us
+	 * in the chain of fragments so far.  We must know where to put
+	 * this fragment, right?
+	 */
+	prev = fq->q.fragments_tail;
+	if (!prev || NFCT_FRAG6_CB(prev)->offset < offset) {
+		next = NULL;
+		goto found;
+	}
+	prev = NULL;
+	for (next = fq->q.fragments; next != NULL; next = next->next) {
+		if (NFCT_FRAG6_CB(next)->offset >= offset)
+			break;	/* bingo! */
+		prev = next;
+	}
+
+found:
+	/* RFC5722, Section 4:
+	 *                                  When reassembling an IPv6 datagram, if
+	 *   one or more its constituent fragments is determined to be an
+	 *   overlapping fragment, the entire datagram (and any constituent
+	 *   fragments, including those not yet received) MUST be silently
+	 *   discarded.
+	 */
+
+	/* Check for overlap with preceding fragment. */
+	if (prev &&
+	    (NFCT_FRAG6_CB(prev)->offset + prev->len) > offset)
+		goto discard_fq;
+
+	/* Look for overlap with succeeding segment. */
+	if (next && NFCT_FRAG6_CB(next)->offset < end)
+		goto discard_fq;
+
+	NFCT_FRAG6_CB(skb)->offset = offset;
+
+	/* Insert this fragment in the chain of fragments. */
+	skb->next = next;
+	if (!next)
+		fq->q.fragments_tail = skb;
+	if (prev)
+		prev->next = skb;
+	else
+		fq->q.fragments = skb;
+
+	skb->dev = NULL;
+	fq->q.stamp = skb->tstamp;
+	fq->q.meat += skb->len;
+	atomic_add(skb->truesize, &nf_init_frags.mem);
+
+	/* The first fragment.
+	 * nhoffset is obtained from the first fragment, of course.
+	 */
+	if (offset == 0) {
+		fq->nhoffset = nhoff;
+		fq->q.last_in |= INET_FRAG_FIRST_IN;
+	}
+	write_lock(&nf_frags.lock);
+	list_move_tail(&fq->q.lru_list, &nf_init_frags.lru_list);
+	write_unlock(&nf_frags.lock);
+	return 0;
+
+discard_fq:
+	fq_kill(fq);
+err:
+	return -1;
+}
+
+/*
+ *	Check if this packet is complete.
+ *	Returns NULL on failure by any reason, and pointer
+ *	to current nexthdr field in reassembled frame.
+ *
+ *	It is called with locked fq, and caller must check that
+ *	queue is eligible for reassembly i.e. it is not COMPLETE,
+ *	the last and the first frames arrived and all the bits are here.
+ */
+static struct sk_buff *
+nf_ct_frag6_reasm(struct nf_ct_frag6_queue *fq, struct net_device *dev)
+{
+	struct sk_buff *fp, *op, *head = fq->q.fragments;
+	int    payload_len;
+
+	fq_kill(fq);
+
+	WARN_ON(head == NULL);
+	WARN_ON(NFCT_FRAG6_CB(head)->offset != 0);
+
+	/* Unfragmented part is taken from the first segment. */
+	payload_len = ((head->data - skb_network_header(head)) -
+		       sizeof(struct ipv6hdr) + fq->q.len -
+		       sizeof(struct frag_hdr));
+	if (payload_len > IPV6_MAXPLEN) {
+		pr_debug("payload len is too large.\n");
+		goto out_oversize;
+	}
+
+	/* Head of list must not be cloned. */
+	if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) {
+		pr_debug("skb is cloned but can't expand head");
+		goto out_oom;
+	}
+
+	/* 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;
+
+		if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) {
+			pr_debug("Can't alloc skb\n");
+			goto out_oom;
+		}
+		clone->next = head->next;
+		head->next = clone;
+		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_shinfo(head)->frags[i].size;
+		clone->len = clone->data_len = head->data_len - plen;
+		head->data_len -= clone->len;
+		head->len -= clone->len;
+		clone->csum = 0;
+		clone->ip_summed = head->ip_summed;
+
+		NFCT_FRAG6_CB(clone)->orig = NULL;
+		atomic_add(clone->truesize, &nf_init_frags.mem);
+	}
+
+	/* We have to remove fragment header from datagram and to relocate
+	 * header in order to calculate ICV correctly. */
+	skb_network_header(head)[fq->nhoffset] = skb_transport_header(head)[0];
+	memmove(head->head + sizeof(struct frag_hdr), head->head,
+		(head->data - head->head) - sizeof(struct frag_hdr));
+	head->mac_header += sizeof(struct frag_hdr);
+	head->network_header += sizeof(struct frag_hdr);
+
+	skb_shinfo(head)->frag_list = head->next;
+	skb_reset_transport_header(head);
+	skb_push(head, head->data - skb_network_header(head));
+
+	for (fp=head->next; fp; fp = fp->next) {
+		head->data_len += fp->len;
+		head->len += fp->len;
+		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);
+		head->truesize += fp->truesize;
+	}
+	atomic_sub(head->truesize, &nf_init_frags.mem);
+
+	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;
+	fq->q.fragments_tail = NULL;
+
+	/* all original skbs are linked into the NFCT_FRAG6_CB(head).orig */
+	fp = skb_shinfo(head)->frag_list;
+	if (fp && 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 (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 = (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, u32 user)
+{
+	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 (atomic_read(&nf_init_frags.mem) > nf_init_frags.high_thresh)
+		nf_ct_frag6_evictor();
+
+	fq = fq_find(fhdr->identification, user, &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(NFPROTO_IPV6, 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 = IPV6_FRAG_HIGH_THRESH;
+	nf_init_frags.low_thresh = IPV6_FRAG_LOW_THRESH;
+	inet_frags_init_net(&nf_init_frags);
+	inet_frags_init(&nf_frags);
+
+#ifdef CONFIG_SYSCTL
+	nf_ct_frag6_sysctl_header = register_sysctl_paths(nf_net_netfilter_sysctl_path,
+							  nf_ct_frag6_sysctl_table);
+	if (!nf_ct_frag6_sysctl_header) {
+		inet_frags_fini(&nf_frags);
+		return -ENOMEM;
+	}
+#endif
+
+	return 0;
+}
+
+void nf_ct_frag6_cleanup(void)
+{
+#ifdef CONFIG_SYSCTL
+	unregister_sysctl_table(nf_ct_frag6_sysctl_header);
+	nf_ct_frag6_sysctl_header = NULL;
+#endif
+	inet_frags_fini(&nf_frags);
+
+	nf_init_frags.low_thresh = 0;
+	nf_ct_frag6_evictor();
+}