Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index d3fd2d7..1f5d4d1 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *	IPv6 fragment reassembly
  *	Linux INET6 implementation
@@ -6,11 +7,6 @@
  *	Pedro Roque		<roque@di.fc.ul.pt>
  *
  *	Based on: net/ipv4/ip_fragment.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.
  */
 
 /*
@@ -69,19 +65,17 @@
 
 static struct inet_frags ip6_frags;
 
-static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
-			  struct net_device *dev);
+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;
-	struct net *net;
 
 	fq = container_of(frag, struct frag_queue, q);
-	net = container_of(fq->q.net, struct net, ipv6.frags);
 
-	ip6frag_expire_frag_queue(net, fq);
+	ip6frag_expire_frag_queue(fq->q.fqdir->net, fq);
 }
 
 static struct frag_queue *
@@ -100,7 +94,7 @@
 					    IPV6_ADDR_LINKLOCAL)))
 		key.iif = 0;
 
-	q = inet_frag_find(&net->ipv6.frags, &key);
+	q = inet_frag_find(net->ipv6.fqdir, &key);
 	if (!q)
 		return NULL;
 
@@ -111,21 +105,26 @@
 			  struct frag_hdr *fhdr, int nhoff,
 			  u32 *prob_offset)
 {
-	struct sk_buff *prev, *next;
-	struct net_device *dev;
-	int offset, end, fragsize;
 	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;
 	}
 
@@ -145,7 +144,7 @@
 		 */
 		if (end < fq->q.len ||
 		    ((fq->q.flags & INET_FRAG_LAST_IN) && end != fq->q.len))
-			goto err;
+			goto discard_fq;
 		fq->q.flags |= INET_FRAG_LAST_IN;
 		fq->q.len = end;
 	} else {
@@ -162,75 +161,40 @@
 		if (end > fq->q.len) {
 			/* Some bits beyond end -> corruption. */
 			if (fq->q.flags & INET_FRAG_LAST_IN)
-				goto err;
+				goto discard_fq;
 			fq->q.len = end;
 		}
 	}
 
 	if (end == offset)
-		goto err;
+		goto discard_fq;
 
+	err = -ENOMEM;
 	/* Point into the IP datagram 'data' part. */
 	if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data))
-		goto err;
-
-	if (pskb_trim_rcsum(skb, end - offset))
-		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 || prev->ip_defrag_offset < offset) {
-		next = NULL;
-		goto found;
-	}
-	prev = NULL;
-	for (next = fq->q.fragments; next != NULL; next = next->next) {
-		if (next->ip_defrag_offset >= offset)
-			break;	/* bingo! */
-		prev = next;
-	}
-
-found:
-	/* RFC5722, Section 4, amended by Errata ID : 3089
-	 *                          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) MUST be silently discarded.
-	 */
-
-	/* Check for overlap with preceding fragment. */
-	if (prev &&
-	    (prev->ip_defrag_offset + prev->len) > offset)
 		goto discard_fq;
 
-	/* Look for overlap with succeeding segment. */
-	if (next && next->ip_defrag_offset < end)
+	err = pskb_trim_rcsum(skb, end - offset);
+	if (err)
 		goto discard_fq;
 
-	/* Note : skb->ip_defrag_offset and skb->dev share the same location */
+	/* Note : skb->rbnode and skb->dev share the same location. */
 	dev = skb->dev;
-	if (dev)
-		fq->iif = dev->ifindex;
 	/* Makes sure compiler wont do silly aliasing games */
 	barrier();
-	skb->ip_defrag_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;
+	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.net, skb->truesize);
+	add_frag_mem_limit(fq->q.fqdir, skb->truesize);
 
 	fragsize = -skb_network_offset(skb) + skb->len;
 	if (fragsize > fq->q.max_size)
@@ -246,44 +210,48 @@
 
 	if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
 	    fq->q.meat == fq->q.len) {
-		int res;
 		unsigned long orefdst = skb->_skb_refdst;
 
 		skb->_skb_refdst = 0UL;
-		res = ip6_frag_reasm(fq, prev, dev);
+		err = ip6_frag_reasm(fq, skb, prev_tail, dev);
 		skb->_skb_refdst = orefdst;
-		return res;
+		return err;
 	}
 
 	skb_dst_drop(skb);
-	return -1;
+	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);
-err:
 	__IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
 			IPSTATS_MIB_REASMFAILS);
+err:
 	kfree_skb(skb);
-	return -1;
+	return err;
 }
 
 /*
  *	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 int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev,
-			  struct net_device *dev)
+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 = container_of(fq->q.net, struct net, ipv6.frags);
-	struct sk_buff *fp, *head = fq->q.fragments;
-	int    payload_len, delta;
+	struct net *net = fq->q.fqdir->net;
 	unsigned int nhoff;
-	int sum_truesize;
+	void *reasm_data;
+	int payload_len;
 	u8 ecn;
 
 	inet_frag_kill(&fq->q);
@@ -292,127 +260,47 @@
 	if (unlikely(ecn == 0xff))
 		goto out_fail;
 
-	/* Make the one we just received the head. */
-	if (prev) {
-		head = prev->next;
-		fp = skb_clone(head, GFP_ATOMIC);
+	reasm_data = inet_frag_reasm_prepare(&fq->q, skb, prev_tail);
+	if (!reasm_data)
+		goto out_oom;
 
-		if (!fp)
-			goto out_oom;
-
-		fp->next = head->next;
-		if (!fp->next)
-			fq->q.fragments_tail = fp;
-		prev->next = fp;
-
-		skb_morph(head, fq->q.fragments);
-		head->next = fq->q.fragments->next;
-
-		consume_skb(fq->q.fragments);
-		fq->q.fragments = head;
-	}
-
-	WARN_ON(head == NULL);
-	WARN_ON(head->ip_defrag_offset != 0);
-
-	/* Unfragmented part is taken from the first segment. */
-	payload_len = ((head->data - skb_network_header(head)) -
+	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;
 
-	delta = - head->truesize;
-
-	/* Head of list must not be cloned. */
-	if (skb_unclone(head, GFP_ATOMIC))
-		goto out_oom;
-
-	delta += head->truesize;
-	if (delta)
-		add_frag_mem_limit(fq->q.net, delta);
-
-	/* 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;
-
-		clone = alloc_skb(0, GFP_ATOMIC);
-		if (!clone)
-			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_frag_size(&skb_shinfo(head)->frags[i]);
-		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;
-		add_frag_mem_limit(fq->q.net, clone->truesize);
-	}
-
 	/* We have to remove fragment header from datagram and to relocate
 	 * header in order to calculate ICV correctly. */
 	nhoff = fq->nhoffset;
-	skb_network_header(head)[nhoff] = skb_transport_header(head)[0];
-	memmove(head->head + sizeof(struct frag_hdr), head->head,
-		(head->data - head->head) - sizeof(struct frag_hdr));
-	if (skb_mac_header_was_set(head))
-		head->mac_header += sizeof(struct frag_hdr);
-	head->network_header += sizeof(struct frag_hdr);
+	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(head);
-	skb_push(head, head->data - skb_network_header(head));
+	skb_reset_transport_header(skb);
 
-	sum_truesize = head->truesize;
-	for (fp = head->next; fp;) {
-		bool headstolen;
-		int delta;
-		struct sk_buff *next = fp->next;
+	inet_frag_reasm_finish(&fq->q, skb, reasm_data, true);
 
-		sum_truesize += fp->truesize;
-		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);
-
-		if (skb_try_coalesce(head, fp, &headstolen, &delta)) {
-			kfree_skb_partial(fp, headstolen);
-		} else {
-			if (!skb_shinfo(head)->frag_list)
-				skb_shinfo(head)->frag_list = fp;
-			head->data_len += fp->len;
-			head->len += fp->len;
-			head->truesize += fp->truesize;
-		}
-		fp = next;
-	}
-	sub_frag_mem_limit(fq->q.net, sum_truesize);
-
-	head->next = NULL;
-	head->dev = dev;
-	head->tstamp = fq->q.stamp;
-	ipv6_hdr(head)->payload_len = htons(payload_len);
-	ipv6_change_dsfield(ipv6_hdr(head), 0xff, ecn);
-	IP6CB(head)->nhoff = nhoff;
-	IP6CB(head)->flags |= IP6SKB_FRAGMENTED;
-	IP6CB(head)->frag_max_size = fq->q.max_size;
+	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(head, skb_network_header(head),
-			   skb_network_header_len(head));
+	skb_postpush_rcsum(skb, skb_network_header(skb),
+			   skb_network_header_len(skb));
 
 	rcu_read_lock();
-	__IP6_INC_STATS(net, __in6_dev_get(dev), IPSTATS_MIB_REASMOKS);
+	__IP6_INC_STATS(net, __in6_dev_stats_get(dev, skb), IPSTATS_MIB_REASMOKS);
 	rcu_read_unlock();
-	fq->q.fragments = NULL;
 	fq->q.rb_fragments = RB_ROOT;
 	fq->q.fragments_tail = NULL;
+	fq->q.last_run_head = NULL;
 	return 1;
 
 out_oversize:
@@ -422,8 +310,9 @@
 	net_dbg_ratelimited("ip6_frag_reasm: no memory for reassembly\n");
 out_fail:
 	rcu_read_lock();
-	__IP6_INC_STATS(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
+	__IP6_INC_STATS(net, __in6_dev_stats_get(dev, skb), IPSTATS_MIB_REASMFAILS);
 	rcu_read_unlock();
+	inet_frag_kill(&fq->q);
 	return -1;
 }
 
@@ -462,10 +351,6 @@
 		return 1;
 	}
 
-	if (skb->len - skb_network_offset(skb) < IPV6_MIN_MTU &&
-	    fhdr->frag_off & htons(IP6_MF))
-		goto fail_hdr;
-
 	iif = skb->dev ? skb->dev->ifindex : 0;
 	fq = fq_find(net, fhdr->identification, hdr, iif);
 	if (fq) {
@@ -483,6 +368,7 @@
 		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;
@@ -509,23 +395,18 @@
 static struct ctl_table ip6_frags_ns_ctl_table[] = {
 	{
 		.procname	= "ip6frag_high_thresh",
-		.data		= &init_net.ipv6.frags.high_thresh,
 		.maxlen		= sizeof(unsigned long),
 		.mode		= 0644,
 		.proc_handler	= proc_doulongvec_minmax,
-		.extra1		= &init_net.ipv6.frags.low_thresh
 	},
 	{
 		.procname	= "ip6frag_low_thresh",
-		.data		= &init_net.ipv6.frags.low_thresh,
 		.maxlen		= sizeof(unsigned long),
 		.mode		= 0644,
 		.proc_handler	= proc_doulongvec_minmax,
-		.extra2		= &init_net.ipv6.frags.high_thresh
 	},
 	{
 		.procname	= "ip6frag_time",
-		.data		= &init_net.ipv6.frags.timeout,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
@@ -557,13 +438,12 @@
 		if (!table)
 			goto err_alloc;
 
-		table[0].data = &net->ipv6.frags.high_thresh;
-		table[0].extra1 = &net->ipv6.frags.low_thresh;
-		table[0].extra2 = &init_net.ipv6.frags.high_thresh;
-		table[1].data = &net->ipv6.frags.low_thresh;
-		table[1].extra2 = &net->ipv6.frags.high_thresh;
-		table[2].data = &net->ipv6.frags.timeout;
 	}
+	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)
@@ -626,30 +506,35 @@
 {
 	int res;
 
-	net->ipv6.frags.high_thresh = IPV6_FRAG_HIGH_THRESH;
-	net->ipv6.frags.low_thresh = IPV6_FRAG_LOW_THRESH;
-	net->ipv6.frags.timeout = IPV6_FRAG_TIMEOUT;
-	net->ipv6.frags.f = &ip6_frags;
-
-	res = inet_frags_init_net(&net->ipv6.frags);
+	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)
-		inet_frags_exit_net(&net->ipv6.frags);
+		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);
-	inet_frags_exit_net(&net->ipv6.frags);
+	fqdir_exit(net->ipv6.fqdir);
 }
 
 static struct pernet_operations ip6_frags_ops = {
-	.init = ipv6_frags_init_net,
-	.exit = ipv6_frags_exit_net,
+	.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 = {
@@ -700,8 +585,8 @@
 
 void ipv6_frag_exit(void)
 {
-	inet_frags_fini(&ip6_frags);
 	ip6_frags_sysctl_unregister();
 	unregister_pernet_subsys(&ip6_frags_ops);
 	inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
+	inet_frags_fini(&ip6_frags);
 }