1 files changed, 611 insertions, 0 deletions

diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
new file mode 100644
index 000000000..28e44782c
--- /dev/null
+++ b/net/ipv6/reassembly.c
@@ -0,0 +1,611 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	IPv6 fragment reassembly
+ *	Linux INET6 implementation
+ *
+ *	Authors:
+ *	Pedro Roque		<roque@di.fc.ul.pt>
+ *
+ *	Based on: net/ipv4/ip_fragment.c
+ */
+
+/*
+ *	Fixes:
+ *	Andi Kleen	Make it work with multiple hosts.
+ *			More RFC compliance.
+ *
+ *      Horst von Brand Add missing #include <linux/string.h>
+ *	Alexey Kuznetsov	SMP races, threading, cleanup.
+ *	Patrick McHardy		LRU queue of frag heads for evictor.
+ *	Mitsuru KANDA @USAGI	Register inet6_protocol{}.
+ *	David Stevens and
+ *	YOSHIFUJI,H. @USAGI	Always remove fragment header to
+ *				calculate ICV correctly.
+ */
+
+#define pr_fmt(fmt) "IPv6: " fmt
+
+#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/jhash.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <linux/tcp.h>
+#include <linux/udp.h>
+
+#include <net/sock.h>
+#include <net/snmp.h>
+
+#include <net/ipv6.h>
+#include <net/ip6_route.h>
+#include <net/protocol.h>
+#include <net/transp_v6.h>
+#include <net/rawv6.h>
+#include <net/ndisc.h>
+#include <net/addrconf.h>
+#include <net/ipv6_frag.h>
+#include <net/inet_ecn.h>
+
+static const char ip6_frag_cache_name[] = "ip6-frags";
+
+static u8 ip6_frag_ecn(const struct ipv6hdr *ipv6h)
+{
+	return 1 << (ipv6_get_dsfield(ipv6h) & INET_ECN_MASK);
+}
+
+static struct inet_frags ip6_frags;
+
+static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *skb,
+			  struct sk_buff *prev_tail, struct net_device *dev);
+
+static void ip6_frag_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);
+}
+
+static struct frag_queue *
+fq_find(struct net *net, __be32 id, const struct ipv6hdr *hdr, int iif)
+{
+	struct frag_v6_compare_key key = {
+		.id = id,
+		.saddr = hdr->saddr,
+		.daddr = hdr->daddr,
+		.user = IP6_DEFRAG_LOCAL_DELIVER,
+		.iif = iif,
+	};
+	struct inet_frag_queue *q;
+
+	if (!(ipv6_addr_type(&hdr->daddr) & (IPV6_ADDR_MULTICAST |
+					    IPV6_ADDR_LINKLOCAL)))
+		key.iif = 0;
+
+	q = inet_frag_find(net->ipv6.fqdir, &key);
+	if (!q)
+		return NULL;
+
+	return container_of(q, struct frag_queue, q);
+}
+
+static int ip6_frag_queue(struct frag_queue *fq, struct sk_buff *skb,
+			  struct frag_hdr *fhdr, int nhoff,
+			  u32 *prob_offset)
+{
+	struct net *net = dev_net(skb_dst(skb)->dev);
+	int offset, end, fragsize;
+	struct sk_buff *prev_tail;
+	struct net_device *dev;
+	int err = -ENOENT;
+	u8 ecn;
+
+	if (fq->q.flags & INET_FRAG_COMPLETE)
+		goto err;
+
+	err = -EINVAL;
+	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) {
+		*prob_offset = (u8 *)&fhdr->frag_off - skb_network_header(skb);
+		/* note that if prob_offset is set, the skb is freed elsewhere,
+		 * we do not free it here.
+		 */
+		return -1;
+	}
+
+	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))
+			goto discard_fq;
+		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
+			 */
+			*prob_offset = offsetof(struct ipv6hdr, payload_len);
+			return -1;
+		}
+		if (end > fq->q.len) {
+			/* Some bits beyond end -> corruption. */
+			if (fq->q.flags & INET_FRAG_LAST_IN)
+				goto discard_fq;
+			fq->q.len = end;
+		}
+	}
+
+	if (end == offset)
+		goto discard_fq;
+
+	err = -ENOMEM;
+	/* Point into the IP datagram 'data' part. */
+	if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
+		goto discard_fq;
+
+	err = pskb_trim_rcsum(skb, end - offset);
+	if (err)
+		goto discard_fq;
+
+	/* Note : skb->rbnode and skb->dev share the same location. */
+	dev = skb->dev;
+	/* Makes sure compiler wont do silly aliasing games */
+	barrier();
+
+	prev_tail = fq->q.fragments_tail;
+	err = inet_frag_queue_insert(&fq->q, skb, offset, end);
+	if (err)
+		goto insert_error;
+
+	if (dev)
+		fq->iif = dev->ifindex;
+
+	fq->q.stamp = skb->tstamp;
+	fq->q.meat += skb->len;
+	fq->ecn |= ecn;
+	add_frag_mem_limit(fq->q.fqdir, skb->truesize);
+
+	fragsize = -skb_network_offset(skb) + skb->len;
+	if (fragsize > fq->q.max_size)
+		fq->q.max_size = fragsize;
+
+	/* 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 = ip6_frag_reasm(fq, skb, prev_tail, dev);
+		skb->_skb_refdst = orefdst;
+		return err;
+	}
+
+	skb_dst_drop(skb);
+	return -EINPROGRESS;
+
+insert_error:
+	if (err == IPFRAG_DUP) {
+		kfree_skb(skb);
+		return -EINVAL;
+	}
+	err = -EINVAL;
+	__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
+			IPSTATS_MIB_REASM_OVERLAPS);
+discard_fq:
+	inet_frag_kill(&fq->q);
+	__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
+			IPSTATS_MIB_REASMFAILS);
+err:
+	kfree_skb(skb);
+	return err;
+}
+
+/*
+ *	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 ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *skb,
+			  struct sk_buff *prev_tail, struct net_device *dev)
+{
+	struct net *net = fq->q.fqdir->net;
+	unsigned int nhoff;
+	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 out_fail;
+
+	reasm_data = inet_frag_reasm_prepare(&fq->q, skb, prev_tail);
+	if (!reasm_data)
+		goto out_oom;
+
+	payload_len = ((skb->data - skb_network_header(skb)) -
+		       sizeof(struct ipv6hdr) + fq->q.len -
+		       sizeof(struct frag_hdr));
+	if (payload_len > IPV6_MAXPLEN)
+		goto out_oversize;
+
+	/* We have to remove fragment header from datagram and to relocate
+	 * header in order to calculate ICV correctly. */
+	nhoff = fq->nhoffset;
+	skb_network_header(skb)[nhoff] = skb_transport_header(skb)[0];
+	memmove(skb->head + sizeof(struct frag_hdr), skb->head,
+		(skb->data - skb->head) - sizeof(struct frag_hdr));
+	if (skb_mac_header_was_set(skb))
+		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, true);
+
+	skb->dev = dev;
+	ipv6_hdr(skb)->payload_len = htons(payload_len);
+	ipv6_change_dsfield(ipv6_hdr(skb), 0xff, ecn);
+	IP6CB(skb)->nhoff = nhoff;
+	IP6CB(skb)->flags |= IP6SKB_FRAGMENTED;
+	IP6CB(skb)->frag_max_size = fq->q.max_size;
+
+	/* Yes, and fold redundant checksum back. 8) */
+	skb_postpush_rcsum(skb, skb_network_header(skb),
+			   skb_network_header_len(skb));
+
+	rcu_read_lock();
+	__IP6_INC_STATS(net, __in6_dev_stats_get(dev, skb), IPSTATS_MIB_REASMOKS);
+	rcu_read_unlock();
+	fq->q.rb_fragments = RB_ROOT;
+	fq->q.fragments_tail = NULL;
+	fq->q.last_run_head = NULL;
+	return 1;
+
+out_oversize:
+	net_dbg_ratelimited("ip6_frag_reasm: payload len = %d\n", payload_len);
+	goto out_fail;
+out_oom:
+	net_dbg_ratelimited("ip6_frag_reasm: no memory for reassembly\n");
+out_fail:
+	rcu_read_lock();
+	__IP6_INC_STATS(net, __in6_dev_stats_get(dev, skb), IPSTATS_MIB_REASMFAILS);
+	rcu_read_unlock();
+	inet_frag_kill(&fq->q);
+	return -1;
+}
+
+static int ipv6_frag_rcv(struct sk_buff *skb)
+{
+	struct frag_hdr *fhdr;
+	struct frag_queue *fq;
+	const struct ipv6hdr *hdr = ipv6_hdr(skb);
+	struct net *net = dev_net(skb_dst(skb)->dev);
+	u8 nexthdr;
+	int iif;
+
+	if (IP6CB(skb)->flags & IP6SKB_FRAGMENTED)
+		goto fail_hdr;
+
+	__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMREQDS);
+
+	/* Jumbo payload inhibits frag. header */
+	if (hdr->payload_len == 0)
+		goto fail_hdr;
+
+	if (!pskb_may_pull(skb, (skb_transport_offset(skb) +
+				 sizeof(struct frag_hdr))))
+		goto fail_hdr;
+
+	hdr = ipv6_hdr(skb);
+	fhdr = (struct frag_hdr *)skb_transport_header(skb);
+
+	if (!(fhdr->frag_off & htons(IP6_OFFSET | IP6_MF))) {
+		/* It is not a fragmented frame */
+		skb->transport_header += sizeof(struct frag_hdr);
+		__IP6_INC_STATS(net,
+				ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMOKS);
+
+		IP6CB(skb)->nhoff = (u8 *)fhdr - skb_network_header(skb);
+		IP6CB(skb)->flags |= IP6SKB_FRAGMENTED;
+		IP6CB(skb)->frag_max_size = ntohs(hdr->payload_len) +
+					    sizeof(struct ipv6hdr);
+		return 1;
+	}
+
+	/* RFC 8200, Section 4.5 Fragment Header:
+	 * If the first fragment does not include all headers through an
+	 * Upper-Layer header, then that fragment should be discarded and
+	 * an ICMP Parameter Problem, Code 3, message should be sent to
+	 * the source of the fragment, with the Pointer field set to zero.
+	 */
+	nexthdr = hdr->nexthdr;
+	if (ipv6frag_thdr_truncated(skb, skb_transport_offset(skb), &nexthdr)) {
+		__IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev),
+				IPSTATS_MIB_INHDRERRORS);
+		icmpv6_param_prob(skb, ICMPV6_HDR_INCOMP, 0);
+		return -1;
+	}
+
+	iif = skb->dev ? skb->dev->ifindex : 0;
+	fq = fq_find(net, fhdr->identification, hdr, iif);
+	if (fq) {
+		u32 prob_offset = 0;
+		int ret;
+
+		spin_lock(&fq->q.lock);
+
+		fq->iif = iif;
+		ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff,
+				     &prob_offset);
+
+		spin_unlock(&fq->q.lock);
+		inet_frag_put(&fq->q);
+		if (prob_offset) {
+			__IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev),
+					IPSTATS_MIB_INHDRERRORS);
+			/* icmpv6_param_prob() calls kfree_skb(skb) */
+			icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, prob_offset);
+		}
+		return ret;
+	}
+
+	__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMFAILS);
+	kfree_skb(skb);
+	return -1;
+
+fail_hdr:
+	__IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev),
+			IPSTATS_MIB_INHDRERRORS);
+	icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb_network_header_len(skb));
+	return -1;
+}
+
+static const struct inet6_protocol frag_protocol = {
+	.handler	=	ipv6_frag_rcv,
+	.flags		=	INET6_PROTO_NOPOLICY,
+};
+
+#ifdef CONFIG_SYSCTL
+
+static struct ctl_table ip6_frags_ns_ctl_table[] = {
+	{
+		.procname	= "ip6frag_high_thresh",
+		.maxlen		= sizeof(unsigned long),
+		.mode		= 0644,
+		.proc_handler	= proc_doulongvec_minmax,
+	},
+	{
+		.procname	= "ip6frag_low_thresh",
+		.maxlen		= sizeof(unsigned long),
+		.mode		= 0644,
+		.proc_handler	= proc_doulongvec_minmax,
+	},
+	{
+		.procname	= "ip6frag_time",
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{ }
+};
+
+/* secret interval has been deprecated */
+static int ip6_frags_secret_interval_unused;
+static struct ctl_table ip6_frags_ctl_table[] = {
+	{
+		.procname	= "ip6frag_secret_interval",
+		.data		= &ip6_frags_secret_interval_unused,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{ }
+};
+
+static int __net_init ip6_frags_ns_sysctl_register(struct net *net)
+{
+	struct ctl_table *table;
+	struct ctl_table_header *hdr;
+
+	table = ip6_frags_ns_ctl_table;
+	if (!net_eq(net, &init_net)) {
+		table = kmemdup(table, sizeof(ip6_frags_ns_ctl_table), GFP_KERNEL);
+		if (!table)
+			goto err_alloc;
+
+	}
+	table[0].data	= &net->ipv6.fqdir->high_thresh;
+	table[0].extra1	= &net->ipv6.fqdir->low_thresh;
+	table[1].data	= &net->ipv6.fqdir->low_thresh;
+	table[1].extra2	= &net->ipv6.fqdir->high_thresh;
+	table[2].data	= &net->ipv6.fqdir->timeout;
+
+	hdr = register_net_sysctl(net, "net/ipv6", table);
+	if (!hdr)
+		goto err_reg;
+
+	net->ipv6.sysctl.frags_hdr = hdr;
+	return 0;
+
+err_reg:
+	if (!net_eq(net, &init_net))
+		kfree(table);
+err_alloc:
+	return -ENOMEM;
+}
+
+static void __net_exit ip6_frags_ns_sysctl_unregister(struct net *net)
+{
+	struct ctl_table *table;
+
+	table = net->ipv6.sysctl.frags_hdr->ctl_table_arg;
+	unregister_net_sysctl_table(net->ipv6.sysctl.frags_hdr);
+	if (!net_eq(net, &init_net))
+		kfree(table);
+}
+
+static struct ctl_table_header *ip6_ctl_header;
+
+static int ip6_frags_sysctl_register(void)
+{
+	ip6_ctl_header = register_net_sysctl(&init_net, "net/ipv6",
+			ip6_frags_ctl_table);
+	return ip6_ctl_header == NULL ? -ENOMEM : 0;
+}
+
+static void ip6_frags_sysctl_unregister(void)
+{
+	unregister_net_sysctl_table(ip6_ctl_header);
+}
+#else
+static int ip6_frags_ns_sysctl_register(struct net *net)
+{
+	return 0;
+}
+
+static void ip6_frags_ns_sysctl_unregister(struct net *net)
+{
+}
+
+static int ip6_frags_sysctl_register(void)
+{
+	return 0;
+}
+
+static void ip6_frags_sysctl_unregister(void)
+{
+}
+#endif
+
+static int __net_init ipv6_frags_init_net(struct net *net)
+{
+	int res;
+
+	res = fqdir_init(&net->ipv6.fqdir, &ip6_frags, net);
+	if (res < 0)
+		return res;
+
+	net->ipv6.fqdir->high_thresh = IPV6_FRAG_HIGH_THRESH;
+	net->ipv6.fqdir->low_thresh = IPV6_FRAG_LOW_THRESH;
+	net->ipv6.fqdir->timeout = IPV6_FRAG_TIMEOUT;
+
+	res = ip6_frags_ns_sysctl_register(net);
+	if (res < 0)
+		fqdir_exit(net->ipv6.fqdir);
+	return res;
+}
+
+static void __net_exit ipv6_frags_pre_exit_net(struct net *net)
+{
+	fqdir_pre_exit(net->ipv6.fqdir);
+}
+
+static void __net_exit ipv6_frags_exit_net(struct net *net)
+{
+	ip6_frags_ns_sysctl_unregister(net);
+	fqdir_exit(net->ipv6.fqdir);
+}
+
+static struct pernet_operations ip6_frags_ops = {
+	.init		= ipv6_frags_init_net,
+	.pre_exit	= ipv6_frags_pre_exit_net,
+	.exit		= ipv6_frags_exit_net,
+};
+
+static const struct rhashtable_params ip6_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 __init ipv6_frag_init(void)
+{
+	int ret;
+
+	ip6_frags.constructor = ip6frag_init;
+	ip6_frags.destructor = NULL;
+	ip6_frags.qsize = sizeof(struct frag_queue);
+	ip6_frags.frag_expire = ip6_frag_expire;
+	ip6_frags.frags_cache_name = ip6_frag_cache_name;
+	ip6_frags.rhash_params = ip6_rhash_params;
+	ret = inet_frags_init(&ip6_frags);
+	if (ret)
+		goto out;
+
+	ret = inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT);
+	if (ret)
+		goto err_protocol;
+
+	ret = ip6_frags_sysctl_register();
+	if (ret)
+		goto err_sysctl;
+
+	ret = register_pernet_subsys(&ip6_frags_ops);
+	if (ret)
+		goto err_pernet;
+
+out:
+	return ret;
+
+err_pernet:
+	ip6_frags_sysctl_unregister();
+err_sysctl:
+	inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
+err_protocol:
+	inet_frags_fini(&ip6_frags);
+	goto out;
+}
+
+void ipv6_frag_exit(void)
+{
+	ip6_frags_sysctl_unregister();
+	unregister_pernet_subsys(&ip6_frags_ops);
+	inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
+	inet_frags_fini(&ip6_frags);
+}