1 files changed, 568 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 000000000..38db0064d
--- /dev/null
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -0,0 +1,568 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * 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
+ */
+
+#define pr_fmt(fmt) "IPv6-nf: " fmt
+
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/net.h>
+#include <linux/netdevice.h>
+#include <linux/ipv6.h>
+#include <linux/slab.h>
+
+#include <net/ipv6_frag.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>
+#include <net/netns/generic.h>
+
+static const char nf_frags_cache_name[] = "nf-frags";
+
+static unsigned int nf_frag_pernet_id __read_mostly;
+static struct inet_frags nf_frags;
+
+static struct nft_ct_frag6_pernet *nf_frag_pernet(struct net *net)
+{
+	return net_generic(net, nf_frag_pernet_id);
+}
+
+#ifdef CONFIG_SYSCTL
+
+static struct ctl_table nf_ct_frag6_sysctl_table[] = {
+	{
+		.procname	= "nf_conntrack_frag6_timeout",
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{
+		.procname	= "nf_conntrack_frag6_low_thresh",
+		.maxlen		= sizeof(unsigned long),
+		.mode		= 0644,
+		.proc_handler	= proc_doulongvec_minmax,
+	},
+	{
+		.procname	= "nf_conntrack_frag6_high_thresh",
+		.maxlen		= sizeof(unsigned long),
+		.mode		= 0644,
+		.proc_handler	= proc_doulongvec_minmax,
+	},
+	{ }
+};
+
+static int nf_ct_frag6_sysctl_register(struct net *net)
+{
+	struct nft_ct_frag6_pernet *nf_frag;
+	struct ctl_table *table;
+	struct ctl_table_header *hdr;
+
+	table = nf_ct_frag6_sysctl_table;
+	if (!net_eq(net, &init_net)) {
+		table = kmemdup(table, sizeof(nf_ct_frag6_sysctl_table),
+				GFP_KERNEL);
+		if (table == NULL)
+			goto err_alloc;
+	}
+
+	nf_frag = nf_frag_pernet(net);
+
+	table[0].data	= &nf_frag->fqdir->timeout;
+	table[1].data	= &nf_frag->fqdir->low_thresh;
+	table[1].extra2	= &nf_frag->fqdir->high_thresh;
+	table[2].data	= &nf_frag->fqdir->high_thresh;
+	table[2].extra1	= &nf_frag->fqdir->low_thresh;
+
+	hdr = register_net_sysctl(net, "net/netfilter", table);
+	if (hdr == NULL)
+		goto err_reg;
+
+	nf_frag->nf_frag_frags_hdr = hdr;
+	return 0;
+
+err_reg:
+	if (!net_eq(net, &init_net))
+		kfree(table);
+err_alloc:
+	return -ENOMEM;
+}
+
+static void __net_exit nf_ct_frags6_sysctl_unregister(struct net *net)
+{
+	struct nft_ct_frag6_pernet *nf_frag = nf_frag_pernet(net);
+	struct ctl_table *table;
+
+	table = nf_frag->nf_frag_frags_hdr->ctl_table_arg;
+	unregister_net_sysctl_table(nf_frag->nf_frag_frags_hdr);
+	if (!net_eq(net, &init_net))
+		kfree(table);
+}
+
+#else
+static int nf_ct_frag6_sysctl_register(struct net *net)
+{
+	return 0;
+}
+static void __net_exit nf_ct_frags6_sysctl_unregister(struct net *net)
+{
+}
+#endif
+
+static int nf_ct_frag6_reasm(struct frag_queue *fq, struct sk_buff *skb,
+			     struct sk_buff *prev_tail, struct net_device *dev);
+
+static inline u8 ip6_frag_ecn(const struct ipv6hdr *ipv6h)
+{
+	return 1 << (ipv6_get_dsfield(ipv6h) & INET_ECN_MASK);
+}
+
+static void nf_ct_frag6_expire(struct timer_list *t)
+{
+	struct inet_frag_queue *frag = from_timer(frag, t, timer);
+	struct frag_queue *fq;
+
+	fq = container_of(frag, struct frag_queue, q);
+
+	ip6frag_expire_frag_queue(fq->q.fqdir->net, fq);
+}
+
+/* Creation primitives. */
+static struct frag_queue *fq_find(struct net *net, __be32 id, u32 user,
+				  const struct ipv6hdr *hdr, int iif)
+{
+	struct nft_ct_frag6_pernet *nf_frag = nf_frag_pernet(net);
+	struct frag_v6_compare_key key = {
+		.id = id,
+		.saddr = hdr->saddr,
+		.daddr = hdr->daddr,
+		.user = user,
+		.iif = iif,
+	};
+	struct inet_frag_queue *q;
+
+	q = inet_frag_find(nf_frag->fqdir, &key);
+	if (!q)
+		return NULL;
+
+	return container_of(q, struct frag_queue, q);
+}
+
+
+static int nf_ct_frag6_queue(struct frag_queue *fq, struct sk_buff *skb,
+			     const struct frag_hdr *fhdr, int nhoff)
+{
+	unsigned int payload_len;
+	struct net_device *dev;
+	struct sk_buff *prev;
+	int offset, end, err;
+	u8 ecn;
+
+	if (fq->q.flags & INET_FRAG_COMPLETE) {
+		pr_debug("Already completed\n");
+		goto err;
+	}
+
+	payload_len = ntohs(ipv6_hdr(skb)->payload_len);
+
+	offset = ntohs(fhdr->frag_off) & ~0x7;
+	end = offset + (payload_len -
+			((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1)));
+
+	if ((unsigned int)end > IPV6_MAXPLEN) {
+		pr_debug("offset is too large.\n");
+		return -EINVAL;
+	}
+
+	ecn = ip6_frag_ecn(ipv6_hdr(skb));
+
+	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.flags & INET_FRAG_LAST_IN) && end != fq->q.len)) {
+			pr_debug("already received last fragment\n");
+			goto err;
+		}
+		fq->q.flags |= 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");
+			inet_frag_kill(&fq->q);
+			return -EPROTO;
+		}
+		if (end > fq->q.len) {
+			/* Some bits beyond end -> corruption. */
+			if (fq->q.flags & 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;
+	}
+
+	/* Note : skb->rbnode and skb->dev share the same location. */
+	dev = skb->dev;
+	/* Makes sure compiler wont do silly aliasing games */
+	barrier();
+
+	prev = fq->q.fragments_tail;
+	err = inet_frag_queue_insert(&fq->q, skb, offset, end);
+	if (err) {
+		if (err == IPFRAG_DUP) {
+			/* No error for duplicates, pretend they got queued. */
+			kfree_skb(skb);
+			return -EINPROGRESS;
+		}
+		goto insert_error;
+	}
+
+	if (dev)
+		fq->iif = dev->ifindex;
+
+	fq->q.stamp = skb->tstamp;
+	fq->q.mono_delivery_time = skb->mono_delivery_time;
+	fq->q.meat += skb->len;
+	fq->ecn |= ecn;
+	if (payload_len > fq->q.max_size)
+		fq->q.max_size = payload_len;
+	add_frag_mem_limit(fq->q.fqdir, skb->truesize);
+
+	/* The first fragment.
+	 * nhoffset is obtained from the first fragment, of course.
+	 */
+	if (offset == 0) {
+		fq->nhoffset = nhoff;
+		fq->q.flags |= INET_FRAG_FIRST_IN;
+	}
+
+	if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
+	    fq->q.meat == fq->q.len) {
+		unsigned long orefdst = skb->_skb_refdst;
+
+		skb->_skb_refdst = 0UL;
+		err = nf_ct_frag6_reasm(fq, skb, prev, dev);
+		skb->_skb_refdst = orefdst;
+
+		/* After queue has assumed skb ownership, only 0 or
+		 * -EINPROGRESS must be returned.
+		 */
+		return err ? -EINPROGRESS : 0;
+	}
+
+	skb_dst_drop(skb);
+	return -EINPROGRESS;
+
+insert_error:
+	inet_frag_kill(&fq->q);
+err:
+	skb_dst_drop(skb);
+	return -EINVAL;
+}
+
+/*
+ *	Check if this packet is complete.
+ *
+ *	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 int nf_ct_frag6_reasm(struct frag_queue *fq, struct sk_buff *skb,
+			     struct sk_buff *prev_tail, struct net_device *dev)
+{
+	void *reasm_data;
+	int payload_len;
+	u8 ecn;
+
+	inet_frag_kill(&fq->q);
+
+	ecn = ip_frag_ecn_table[fq->ecn];
+	if (unlikely(ecn == 0xff))
+		goto err;
+
+	reasm_data = inet_frag_reasm_prepare(&fq->q, skb, prev_tail);
+	if (!reasm_data)
+		goto err;
+
+	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);
+		goto err;
+	}
+
+	/* We have to remove fragment header from datagram and to relocate
+	 * header in order to calculate ICV correctly. */
+	skb_network_header(skb)[fq->nhoffset] = skb_transport_header(skb)[0];
+	memmove(skb->head + sizeof(struct frag_hdr), skb->head,
+		(skb->data - skb->head) - sizeof(struct frag_hdr));
+	skb->mac_header += sizeof(struct frag_hdr);
+	skb->network_header += sizeof(struct frag_hdr);
+
+	skb_reset_transport_header(skb);
+
+	inet_frag_reasm_finish(&fq->q, skb, reasm_data, false);
+
+	skb->ignore_df = 1;
+	skb->dev = dev;
+	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;
+
+	/* 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
+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)
+{
+	struct nft_ct_frag6_pernet *nf_frag  = nf_frag_pernet(net);
+	int res;
+
+	res = fqdir_init(&nf_frag->fqdir, &nf_frags, net);
+	if (res < 0)
+		return res;
+
+	nf_frag->fqdir->high_thresh = IPV6_FRAG_HIGH_THRESH;
+	nf_frag->fqdir->low_thresh = IPV6_FRAG_LOW_THRESH;
+	nf_frag->fqdir->timeout = IPV6_FRAG_TIMEOUT;
+
+	res = nf_ct_frag6_sysctl_register(net);
+	if (res < 0)
+		fqdir_exit(nf_frag->fqdir);
+	return res;
+}
+
+static void nf_ct_net_pre_exit(struct net *net)
+{
+	struct nft_ct_frag6_pernet *nf_frag  = nf_frag_pernet(net);
+
+	fqdir_pre_exit(nf_frag->fqdir);
+}
+
+static void nf_ct_net_exit(struct net *net)
+{
+	struct nft_ct_frag6_pernet *nf_frag  = nf_frag_pernet(net);
+
+	nf_ct_frags6_sysctl_unregister(net);
+	fqdir_exit(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,
+	.id		= &nf_frag_pernet_id,
+	.size		= sizeof(struct nft_ct_frag6_pernet),
+};
+
+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);
+}