[linux-2.6-block.git] / net / ipv6 / reassembly.c

// 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,
			  int *refs);

static void ip6_frag_expire(struct timer_list *t)
{
	struct inet_frag_queue *frag = timer_container_of(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, int *refs)
{
	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;
	SKB_DR(reason);
	u8 ecn;

	/* If reassembly is already done, @skb must be a duplicate frag. */
	if (fq->q.flags & INET_FRAG_COMPLETE) {
		SKB_DR_SET(reason, DUP_FRAG);
		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.tstamp_type = skb->tstamp_type;
	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, refs);
		skb->_skb_refdst = orefdst;
		return err;
	}

	skb_dst_drop(skb);
	return -EINPROGRESS;

insert_error:
	if (err == IPFRAG_DUP) {
		SKB_DR_SET(reason, DUP_FRAG);
		err = -EINVAL;
		goto err;
	}
	err = -EINVAL;
	__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
			IPSTATS_MIB_REASM_OVERLAPS);
discard_fq:
	inet_frag_kill(&fq->q, refs);
	__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
			IPSTATS_MIB_REASMFAILS);
err:
	kfree_skb_reason(skb, reason);
	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,
			  int *refs)
{
	struct net *net = fq->q.fqdir->net;
	unsigned int nhoff;
	void *reasm_data;
	int payload_len;
	u8 ecn;

	inet_frag_kill(&fq->q, refs);

	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_network_offset(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));

	__IP6_INC_STATS(net, __in6_dev_stats_get(dev, skb), IPSTATS_MIB_REASMOKS);
	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:
	__IP6_INC_STATS(net, __in6_dev_stats_get(dev, skb), IPSTATS_MIB_REASMFAILS);
	inet_frag_kill(&fq->q, refs);
	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_network_offset(skb) + sizeof(struct ipv6hdr), &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;
	rcu_read_lock();
	fq = fq_find(net, fhdr->identification, hdr, iif);
	if (fq) {
		u32 prob_offset = 0;
		int ret, refs = 0;

		spin_lock(&fq->q.lock);

		fq->iif = iif;
		ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff,
				     &prob_offset, &refs);

		spin_unlock(&fq->q.lock);
		rcu_read_unlock();
		inet_frag_putn(&fq->q, refs);
		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;
	}
	rcu_read_unlock();

	__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_sz(net, "net/ipv6", table,
				     ARRAY_SIZE(ip6_frags_ns_ctl_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)
{
	const 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);
}
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0-or-later
	2	/*
	3	* IPv6 fragment reassembly
	4	* Linux INET6 implementation
	5	*
	6	* Authors:
	7	* Pedro Roque <roque@di.fc.ul.pt>
	8	*
	9	* Based on: net/ipv4/ip_fragment.c
	10	*/
	11
	12	/*
	13	* Fixes:
	14	* Andi Kleen Make it work with multiple hosts.
	15	* More RFC compliance.
	16	*
	17	* Horst von Brand Add missing #include <linux/string.h>
	18	* Alexey Kuznetsov SMP races, threading, cleanup.
	19	* Patrick McHardy LRU queue of frag heads for evictor.
	20	* Mitsuru KANDA @USAGI Register inet6_protocol{}.
	21	* David Stevens and
	22	* YOSHIFUJI,H. @USAGI Always remove fragment header to
	23	* calculate ICV correctly.
	24	*/
	25
	26	#define pr_fmt(fmt) "IPv6: " fmt
	27
	28	#include <linux/errno.h>
	29	#include <linux/types.h>
	30	#include <linux/string.h>
	31	#include <linux/socket.h>
	32	#include <linux/sockios.h>
	33	#include <linux/jiffies.h>
	34	#include <linux/net.h>
	35	#include <linux/list.h>
	36	#include <linux/netdevice.h>
	37	#include <linux/in6.h>
	38	#include <linux/ipv6.h>
	39	#include <linux/icmpv6.h>
	40	#include <linux/random.h>
	41	#include <linux/jhash.h>
	42	#include <linux/skbuff.h>
	43	#include <linux/slab.h>
	44	#include <linux/export.h>
	45	#include <linux/tcp.h>
	46	#include <linux/udp.h>
	47
	48	#include <net/sock.h>
	49	#include <net/snmp.h>
	50
	51	#include <net/ipv6.h>
	52	#include <net/ip6_route.h>
	53	#include <net/protocol.h>
	54	#include <net/transp_v6.h>
	55	#include <net/rawv6.h>
	56	#include <net/ndisc.h>
	57	#include <net/addrconf.h>
	58	#include <net/ipv6_frag.h>
	59	#include <net/inet_ecn.h>
	60
	61	static const char ip6_frag_cache_name[] = "ip6-frags";
	62
	63	static u8 ip6_frag_ecn(const struct ipv6hdr *ipv6h)
	64	{
	65	return 1 << (ipv6_get_dsfield(ipv6h) & INET_ECN_MASK);
	66	}
	67
	68	static struct inet_frags ip6_frags;
	69
	70	static int ip6_frag_reasm(struct frag_queue fq, struct sk_buff skb,
	71	struct sk_buff prev_tail, struct net_device dev,
	72	int *refs);
	73
	74	static void ip6_frag_expire(struct timer_list *t)
	75	{
	76	struct inet_frag_queue *frag = timer_container_of(frag, t, timer);
	77	struct frag_queue *fq;
	78
	79	fq = container_of(frag, struct frag_queue, q);
	80
	81	ip6frag_expire_frag_queue(fq->q.fqdir->net, fq);
	82	}
	83
	84	static struct frag_queue *
	85	fq_find(struct net net, __be32 id, const struct ipv6hdr hdr, int iif)
	86	{
	87	struct frag_v6_compare_key key = {
	88	.id = id,
	89	.saddr = hdr->saddr,
	90	.daddr = hdr->daddr,
	91	.user = IP6_DEFRAG_LOCAL_DELIVER,
	92	.iif = iif,
	93	};
	94	struct inet_frag_queue *q;
	95
	96	if (!(ipv6_addr_type(&hdr->daddr) & (IPV6_ADDR_MULTICAST \|
	97	IPV6_ADDR_LINKLOCAL)))
	98	key.iif = 0;
	99
	100	q = inet_frag_find(net->ipv6.fqdir, &key);
	101	if (!q)
	102	return NULL;
	103
	104	return container_of(q, struct frag_queue, q);
	105	}
	106
	107	static int ip6_frag_queue(struct frag_queue fq, struct sk_buff skb,
	108	struct frag_hdr *fhdr, int nhoff,
	109	u32 prob_offset, int refs)
	110	{
	111	struct net *net = dev_net(skb_dst(skb)->dev);
	112	int offset, end, fragsize;
	113	struct sk_buff *prev_tail;
	114	struct net_device *dev;
	115	int err = -ENOENT;
	116	SKB_DR(reason);
	117	u8 ecn;
	118
	119	/* If reassembly is already done, @skb must be a duplicate frag. */
	120	if (fq->q.flags & INET_FRAG_COMPLETE) {
	121	SKB_DR_SET(reason, DUP_FRAG);
	122	goto err;
	123	}
	124
	125	err = -EINVAL;
	126	offset = ntohs(fhdr->frag_off) & ~0x7;
	127	end = offset + (ntohs(ipv6_hdr(skb)->payload_len) -
	128	((u8 )(fhdr + 1) - (u8 )(ipv6_hdr(skb) + 1)));
	129
	130	if ((unsigned int)end > IPV6_MAXPLEN) {
	131	prob_offset = (u8 )&fhdr->frag_off - skb_network_header(skb);
	132	/* note that if prob_offset is set, the skb is freed elsewhere,
	133	* we do not free it here.
	134	*/
	135	return -1;
	136	}
	137
	138	ecn = ip6_frag_ecn(ipv6_hdr(skb));
	139
	140	if (skb->ip_summed == CHECKSUM_COMPLETE) {
	141	const unsigned char *nh = skb_network_header(skb);
	142	skb->csum = csum_sub(skb->csum,
	143	csum_partial(nh, (u8 *)(fhdr + 1) - nh,
	144	0));
	145	}
	146
	147	/* Is this the final fragment? */
	148	if (!(fhdr->frag_off & htons(IP6_MF))) {
	149	/* If we already have some bits beyond end
	150	* or have different end, the segment is corrupted.
	151	*/
	152	if (end < fq->q.len \|\|
	153	((fq->q.flags & INET_FRAG_LAST_IN) && end != fq->q.len))
	154	goto discard_fq;
	155	fq->q.flags \|= INET_FRAG_LAST_IN;
	156	fq->q.len = end;
	157	} else {
	158	/* Check if the fragment is rounded to 8 bytes.
	159	* Required by the RFC.
	160	*/
	161	if (end & 0x7) {
	162	/* RFC2460 says always send parameter problem in
	163	* this case. -DaveM
	164	*/
	165	*prob_offset = offsetof(struct ipv6hdr, payload_len);
	166	return -1;
	167	}
	168	if (end > fq->q.len) {
	169	/* Some bits beyond end -> corruption. */
	170	if (fq->q.flags & INET_FRAG_LAST_IN)
	171	goto discard_fq;
	172	fq->q.len = end;
	173	}
	174	}
	175
	176	if (end == offset)
	177	goto discard_fq;
	178
	179	err = -ENOMEM;
	180	/* Point into the IP datagram 'data' part. */
	181	if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
	182	goto discard_fq;
	183
	184	err = pskb_trim_rcsum(skb, end - offset);
	185	if (err)
	186	goto discard_fq;
	187
	188	/* Note : skb->rbnode and skb->dev share the same location. */
	189	dev = skb->dev;
	190	/* Makes sure compiler wont do silly aliasing games */
	191	barrier();
	192
	193	prev_tail = fq->q.fragments_tail;
	194	err = inet_frag_queue_insert(&fq->q, skb, offset, end);
	195	if (err)
	196	goto insert_error;
	197
	198	if (dev)
	199	fq->iif = dev->ifindex;
	200
	201	fq->q.stamp = skb->tstamp;
	202	fq->q.tstamp_type = skb->tstamp_type;
	203	fq->q.meat += skb->len;
	204	fq->ecn \|= ecn;
	205	add_frag_mem_limit(fq->q.fqdir, skb->truesize);
	206
	207	fragsize = -skb_network_offset(skb) + skb->len;
	208	if (fragsize > fq->q.max_size)
	209	fq->q.max_size = fragsize;
	210
	211	/* The first fragment.
	212	* nhoffset is obtained from the first fragment, of course.
	213	*/
	214	if (offset == 0) {
	215	fq->nhoffset = nhoff;
	216	fq->q.flags \|= INET_FRAG_FIRST_IN;
	217	}
	218
	219	if (fq->q.flags == (INET_FRAG_FIRST_IN \| INET_FRAG_LAST_IN) &&
	220	fq->q.meat == fq->q.len) {
	221	unsigned long orefdst = skb->_skb_refdst;
	222
	223	skb->_skb_refdst = 0UL;
	224	err = ip6_frag_reasm(fq, skb, prev_tail, dev, refs);
	225	skb->_skb_refdst = orefdst;
	226	return err;
	227	}
	228
	229	skb_dst_drop(skb);
	230	return -EINPROGRESS;
	231
	232	insert_error:
	233	if (err == IPFRAG_DUP) {
	234	SKB_DR_SET(reason, DUP_FRAG);
	235	err = -EINVAL;
	236	goto err;
	237	}
	238	err = -EINVAL;
	239	__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
	240	IPSTATS_MIB_REASM_OVERLAPS);
	241	discard_fq:
	242	inet_frag_kill(&fq->q, refs);
	243	__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
	244	IPSTATS_MIB_REASMFAILS);
	245	err:
	246	kfree_skb_reason(skb, reason);
	247	return err;
	248	}
	249
	250	/*
	251	* Check if this packet is complete.
	252	*
	253	* It is called with locked fq, and caller must check that
	254	* queue is eligible for reassembly i.e. it is not COMPLETE,
	255	* the last and the first frames arrived and all the bits are here.
	256	*/
	257	static int ip6_frag_reasm(struct frag_queue fq, struct sk_buff skb,
	258	struct sk_buff prev_tail, struct net_device dev,
	259	int *refs)
	260	{
	261	struct net *net = fq->q.fqdir->net;
	262	unsigned int nhoff;
	263	void *reasm_data;
	264	int payload_len;
	265	u8 ecn;
	266
	267	inet_frag_kill(&fq->q, refs);
	268
	269	ecn = ip_frag_ecn_table[fq->ecn];
	270	if (unlikely(ecn == 0xff))
	271	goto out_fail;
	272
	273	reasm_data = inet_frag_reasm_prepare(&fq->q, skb, prev_tail);
	274	if (!reasm_data)
	275	goto out_oom;
	276
	277	payload_len = -skb_network_offset(skb) -
	278	sizeof(struct ipv6hdr) + fq->q.len -
	279	sizeof(struct frag_hdr);
	280	if (payload_len > IPV6_MAXPLEN)
	281	goto out_oversize;
	282
	283	/* We have to remove fragment header from datagram and to relocate
	284	* header in order to calculate ICV correctly. */
	285	nhoff = fq->nhoffset;
	286	skb_network_header(skb)[nhoff] = skb_transport_header(skb)[0];
	287	memmove(skb->head + sizeof(struct frag_hdr), skb->head,
	288	(skb->data - skb->head) - sizeof(struct frag_hdr));
	289	if (skb_mac_header_was_set(skb))
	290	skb->mac_header += sizeof(struct frag_hdr);
	291	skb->network_header += sizeof(struct frag_hdr);
	292
	293	skb_reset_transport_header(skb);
	294
	295	inet_frag_reasm_finish(&fq->q, skb, reasm_data, true);
	296
	297	skb->dev = dev;
	298	ipv6_hdr(skb)->payload_len = htons(payload_len);
	299	ipv6_change_dsfield(ipv6_hdr(skb), 0xff, ecn);
	300	IP6CB(skb)->nhoff = nhoff;
	301	IP6CB(skb)->flags \|= IP6SKB_FRAGMENTED;
	302	IP6CB(skb)->frag_max_size = fq->q.max_size;
	303
	304	/* Yes, and fold redundant checksum back. 8) */
	305	skb_postpush_rcsum(skb, skb_network_header(skb),
	306	skb_network_header_len(skb));
	307
	308	__IP6_INC_STATS(net, __in6_dev_stats_get(dev, skb), IPSTATS_MIB_REASMOKS);
	309	fq->q.rb_fragments = RB_ROOT;
	310	fq->q.fragments_tail = NULL;
	311	fq->q.last_run_head = NULL;
	312	return 1;
	313
	314	out_oversize:
	315	net_dbg_ratelimited("ip6_frag_reasm: payload len = %d\n", payload_len);
	316	goto out_fail;
	317	out_oom:
	318	net_dbg_ratelimited("ip6_frag_reasm: no memory for reassembly\n");
	319	out_fail:
	320	__IP6_INC_STATS(net, __in6_dev_stats_get(dev, skb), IPSTATS_MIB_REASMFAILS);
	321	inet_frag_kill(&fq->q, refs);
	322	return -1;
	323	}
	324
	325	static int ipv6_frag_rcv(struct sk_buff *skb)
	326	{
	327	struct frag_hdr *fhdr;
	328	struct frag_queue *fq;
	329	const struct ipv6hdr *hdr = ipv6_hdr(skb);
	330	struct net *net = dev_net(skb_dst(skb)->dev);
	331	u8 nexthdr;
	332	int iif;
	333
	334	if (IP6CB(skb)->flags & IP6SKB_FRAGMENTED)
	335	goto fail_hdr;
	336
	337	__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMREQDS);
	338
	339	/* Jumbo payload inhibits frag. header */
	340	if (hdr->payload_len == 0)
	341	goto fail_hdr;
	342
	343	if (!pskb_may_pull(skb, (skb_transport_offset(skb) +
	344	sizeof(struct frag_hdr))))
	345	goto fail_hdr;
	346
	347	hdr = ipv6_hdr(skb);
	348	fhdr = (struct frag_hdr *)skb_transport_header(skb);
	349
	350	if (!(fhdr->frag_off & htons(IP6_OFFSET \| IP6_MF))) {
	351	/* It is not a fragmented frame */
	352	skb->transport_header += sizeof(struct frag_hdr);
	353	__IP6_INC_STATS(net,
	354	ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMOKS);
	355
	356	IP6CB(skb)->nhoff = (u8 *)fhdr - skb_network_header(skb);
	357	IP6CB(skb)->flags \|= IP6SKB_FRAGMENTED;
	358	IP6CB(skb)->frag_max_size = ntohs(hdr->payload_len) +
	359	sizeof(struct ipv6hdr);
	360	return 1;
	361	}
	362
	363	/* RFC 8200, Section 4.5 Fragment Header:
	364	* If the first fragment does not include all headers through an
	365	* Upper-Layer header, then that fragment should be discarded and
	366	* an ICMP Parameter Problem, Code 3, message should be sent to
	367	* the source of the fragment, with the Pointer field set to zero.
	368	*/
	369	nexthdr = hdr->nexthdr;
	370	if (ipv6frag_thdr_truncated(skb, skb_network_offset(skb) + sizeof(struct ipv6hdr), &nexthdr)) {
	371	__IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev),
	372	IPSTATS_MIB_INHDRERRORS);
	373	icmpv6_param_prob(skb, ICMPV6_HDR_INCOMP, 0);
	374	return -1;
	375	}
	376
	377	iif = skb->dev ? skb->dev->ifindex : 0;
	378	rcu_read_lock();
	379	fq = fq_find(net, fhdr->identification, hdr, iif);
	380	if (fq) {
	381	u32 prob_offset = 0;
	382	int ret, refs = 0;
	383
	384	spin_lock(&fq->q.lock);
	385
	386	fq->iif = iif;
	387	ret = ip6_frag_queue(fq, skb, fhdr, IP6CB(skb)->nhoff,
	388	&prob_offset, &refs);
	389
	390	spin_unlock(&fq->q.lock);
	391	rcu_read_unlock();
	392	inet_frag_putn(&fq->q, refs);
	393	if (prob_offset) {
	394	__IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev),
	395	IPSTATS_MIB_INHDRERRORS);
	396	/* icmpv6_param_prob() calls kfree_skb(skb) */
	397	icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, prob_offset);
	398	}
	399	return ret;
	400	}
	401	rcu_read_unlock();
	402
	403	__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_REASMFAILS);
	404	kfree_skb(skb);
	405	return -1;
	406
	407	fail_hdr:
	408	__IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev),
	409	IPSTATS_MIB_INHDRERRORS);
	410	icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, skb_network_header_len(skb));
	411	return -1;
	412	}
	413
	414	static const struct inet6_protocol frag_protocol = {
	415	.handler = ipv6_frag_rcv,
	416	.flags = INET6_PROTO_NOPOLICY,
	417	};
	418
	419	#ifdef CONFIG_SYSCTL
	420
	421	static struct ctl_table ip6_frags_ns_ctl_table[] = {
	422	{
	423	.procname = "ip6frag_high_thresh",
	424	.maxlen = sizeof(unsigned long),
	425	.mode = 0644,
	426	.proc_handler = proc_doulongvec_minmax,
	427	},
	428	{
	429	.procname = "ip6frag_low_thresh",
	430	.maxlen = sizeof(unsigned long),
	431	.mode = 0644,
	432	.proc_handler = proc_doulongvec_minmax,
	433	},
	434	{
	435	.procname = "ip6frag_time",
	436	.maxlen = sizeof(int),
	437	.mode = 0644,
	438	.proc_handler = proc_dointvec_jiffies,
	439	},
	440	};
	441
	442	/* secret interval has been deprecated */
	443	static int ip6_frags_secret_interval_unused;
	444	static struct ctl_table ip6_frags_ctl_table[] = {
	445	{
	446	.procname = "ip6frag_secret_interval",
	447	.data = &ip6_frags_secret_interval_unused,
	448	.maxlen = sizeof(int),
	449	.mode = 0644,
	450	.proc_handler = proc_dointvec_jiffies,
	451	},
	452	};
	453
	454	static int __net_init ip6_frags_ns_sysctl_register(struct net *net)
	455	{
	456	struct ctl_table *table;
	457	struct ctl_table_header *hdr;
	458
	459	table = ip6_frags_ns_ctl_table;
	460	if (!net_eq(net, &init_net)) {
	461	table = kmemdup(table, sizeof(ip6_frags_ns_ctl_table), GFP_KERNEL);
	462	if (!table)
	463	goto err_alloc;
	464
	465	}
	466	table[0].data = &net->ipv6.fqdir->high_thresh;
	467	table[0].extra1 = &net->ipv6.fqdir->low_thresh;
	468	table[1].data = &net->ipv6.fqdir->low_thresh;
	469	table[1].extra2 = &net->ipv6.fqdir->high_thresh;
	470	table[2].data = &net->ipv6.fqdir->timeout;
	471
	472	hdr = register_net_sysctl_sz(net, "net/ipv6", table,
	473	ARRAY_SIZE(ip6_frags_ns_ctl_table));
	474	if (!hdr)
	475	goto err_reg;
	476
	477	net->ipv6.sysctl.frags_hdr = hdr;
	478	return 0;
	479
	480	err_reg:
	481	if (!net_eq(net, &init_net))
	482	kfree(table);
	483	err_alloc:
	484	return -ENOMEM;
	485	}
	486
	487	static void __net_exit ip6_frags_ns_sysctl_unregister(struct net *net)
	488	{
	489	const struct ctl_table *table;
	490
	491	table = net->ipv6.sysctl.frags_hdr->ctl_table_arg;
	492	unregister_net_sysctl_table(net->ipv6.sysctl.frags_hdr);
	493	if (!net_eq(net, &init_net))
	494	kfree(table);
	495	}
	496
	497	static struct ctl_table_header *ip6_ctl_header;
	498
	499	static int ip6_frags_sysctl_register(void)
	500	{
	501	ip6_ctl_header = register_net_sysctl(&init_net, "net/ipv6",
	502	ip6_frags_ctl_table);
	503	return ip6_ctl_header == NULL ? -ENOMEM : 0;
	504	}
	505
	506	static void ip6_frags_sysctl_unregister(void)
	507	{
	508	unregister_net_sysctl_table(ip6_ctl_header);
	509	}
	510	#else
	511	static int ip6_frags_ns_sysctl_register(struct net *net)
	512	{
	513	return 0;
	514	}
	515
	516	static void ip6_frags_ns_sysctl_unregister(struct net *net)
	517	{
	518	}
	519
	520	static int ip6_frags_sysctl_register(void)
	521	{
	522	return 0;
	523	}
	524
	525	static void ip6_frags_sysctl_unregister(void)
	526	{
	527	}
	528	#endif
	529
	530	static int __net_init ipv6_frags_init_net(struct net *net)
	531	{
	532	int res;
	533
	534	res = fqdir_init(&net->ipv6.fqdir, &ip6_frags, net);
	535	if (res < 0)
	536	return res;
	537
	538	net->ipv6.fqdir->high_thresh = IPV6_FRAG_HIGH_THRESH;
	539	net->ipv6.fqdir->low_thresh = IPV6_FRAG_LOW_THRESH;
	540	net->ipv6.fqdir->timeout = IPV6_FRAG_TIMEOUT;
	541
	542	res = ip6_frags_ns_sysctl_register(net);
	543	if (res < 0)
	544	fqdir_exit(net->ipv6.fqdir);
	545	return res;
	546	}
	547
	548	static void __net_exit ipv6_frags_pre_exit_net(struct net *net)
	549	{
	550	fqdir_pre_exit(net->ipv6.fqdir);
	551	}
	552
	553	static void __net_exit ipv6_frags_exit_net(struct net *net)
	554	{
	555	ip6_frags_ns_sysctl_unregister(net);
	556	fqdir_exit(net->ipv6.fqdir);
	557	}
	558
	559	static struct pernet_operations ip6_frags_ops = {
	560	.init = ipv6_frags_init_net,
	561	.pre_exit = ipv6_frags_pre_exit_net,
	562	.exit = ipv6_frags_exit_net,
	563	};
	564
	565	static const struct rhashtable_params ip6_rhash_params = {
	566	.head_offset = offsetof(struct inet_frag_queue, node),
	567	.hashfn = ip6frag_key_hashfn,
	568	.obj_hashfn = ip6frag_obj_hashfn,
	569	.obj_cmpfn = ip6frag_obj_cmpfn,
	570	.automatic_shrinking = true,
	571	};
	572
	573	int __init ipv6_frag_init(void)
	574	{
	575	int ret;
	576
	577	ip6_frags.constructor = ip6frag_init;
	578	ip6_frags.destructor = NULL;
	579	ip6_frags.qsize = sizeof(struct frag_queue);
	580	ip6_frags.frag_expire = ip6_frag_expire;
	581	ip6_frags.frags_cache_name = ip6_frag_cache_name;
	582	ip6_frags.rhash_params = ip6_rhash_params;
	583	ret = inet_frags_init(&ip6_frags);
	584	if (ret)
	585	goto out;
	586
	587	ret = inet6_add_protocol(&frag_protocol, IPPROTO_FRAGMENT);
	588	if (ret)
	589	goto err_protocol;
	590
	591	ret = ip6_frags_sysctl_register();
	592	if (ret)
	593	goto err_sysctl;
	594
	595	ret = register_pernet_subsys(&ip6_frags_ops);
	596	if (ret)
	597	goto err_pernet;
	598
	599	out:
	600	return ret;
	601
	602	err_pernet:
	603	ip6_frags_sysctl_unregister();
	604	err_sysctl:
	605	inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
	606	err_protocol:
	607	inet_frags_fini(&ip6_frags);
	608	goto out;
	609	}
	610
	611	void ipv6_frag_exit(void)
	612	{
	613	ip6_frags_sysctl_unregister();
	614	unregister_pernet_subsys(&ip6_frags_ops);
	615	inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
	616	inet_frags_fini(&ip6_frags);
	617	}