1 files changed, 550 insertions, 0 deletions
diff --git a/net/ieee802154/6lowpan/reassembly.c b/net/ieee802154/6lowpan/reassembly.c
new file mode 100644
index 000000000..be6f06ade
--- /dev/null
+++ b/net/ieee802154/6lowpan/reassembly.c
@@ -0,0 +1,550 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*	6LoWPAN fragment reassembly
+ *
+ *	Authors:
+ *	Alexander Aring		<aar@pengutronix.de>
+ *
+ *	Based on: net/ipv6/reassembly.c
+ */
+
+#define pr_fmt(fmt) "6LoWPAN: " fmt
+
+#include <linux/net.h>
+#include <linux/list.h>
+#include <linux/netdevice.h>
+#include <linux/random.h>
+#include <linux/jhash.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+
+#include <net/ieee802154_netdev.h>
+#include <net/6lowpan.h>
+#include <net/ipv6_frag.h>
+#include <net/inet_frag.h>
+#include <net/ip.h>
+
+#include "6lowpan_i.h"
+
+static const char lowpan_frags_cache_name[] = "lowpan-frags";
+
+static struct inet_frags lowpan_frags;
+
+static int lowpan_frag_reasm(struct lowpan_frag_queue *fq, struct sk_buff *skb,
+			     struct sk_buff *prev,  struct net_device *ldev);
+
+static void lowpan_frag_init(struct inet_frag_queue *q, const void *a)
+{
+	const struct frag_lowpan_compare_key *key = a;
+
+	BUILD_BUG_ON(sizeof(*key) > sizeof(q->key));
+	memcpy(&q->key, key, sizeof(*key));
+}
+
+static void lowpan_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);
+
+	spin_lock(&fq->q.lock);
+
+	if (fq->q.flags & INET_FRAG_COMPLETE)
+		goto out;
+
+	inet_frag_kill(&fq->q);
+out:
+	spin_unlock(&fq->q.lock);
+	inet_frag_put(&fq->q);
+}
+
+static inline struct lowpan_frag_queue *
+fq_find(struct net *net, const struct lowpan_802154_cb *cb,
+	const struct ieee802154_addr *src,
+	const struct ieee802154_addr *dst)
+{
+	struct netns_ieee802154_lowpan *ieee802154_lowpan =
+		net_ieee802154_lowpan(net);
+	struct frag_lowpan_compare_key key = {};
+	struct inet_frag_queue *q;
+
+	key.tag = cb->d_tag;
+	key.d_size = cb->d_size;
+	key.src = *src;
+	key.dst = *dst;
+
+	q = inet_frag_find(ieee802154_lowpan->fqdir, &key);
+	if (!q)
+		return NULL;
+
+	return container_of(q, struct lowpan_frag_queue, q);
+}
+
+static int lowpan_frag_queue(struct lowpan_frag_queue *fq,
+			     struct sk_buff *skb, u8 frag_type)
+{
+	struct sk_buff *prev_tail;
+	struct net_device *ldev;
+	int end, offset, err;
+
+	/* inet_frag_queue_* functions use skb->cb; see struct ipfrag_skb_cb
+	 * in inet_fragment.c
+	 */
+	BUILD_BUG_ON(sizeof(struct lowpan_802154_cb) > sizeof(struct inet_skb_parm));
+	BUILD_BUG_ON(sizeof(struct lowpan_802154_cb) > sizeof(struct inet6_skb_parm));
+
+	if (fq->q.flags & INET_FRAG_COMPLETE)
+		goto err;
+
+	offset = lowpan_802154_cb(skb)->d_offset << 3;
+	end = lowpan_802154_cb(skb)->d_size;
+
+	/* Is this the final fragment? */
+	if (offset + skb->len == end) {
+		/* 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 err;
+		fq->q.flags |= INET_FRAG_LAST_IN;
+		fq->q.len = end;
+	} else {
+		if (end > fq->q.len) {
+			/* Some bits beyond end -> corruption. */
+			if (fq->q.flags & INET_FRAG_LAST_IN)
+				goto err;
+			fq->q.len = end;
+		}
+	}
+
+	ldev = skb->dev;
+	if (ldev)
+		skb->dev = NULL;
+	barrier();
+
+	prev_tail = fq->q.fragments_tail;
+	err = inet_frag_queue_insert(&fq->q, skb, offset, end);
+	if (err)
+		goto err;
+
+	fq->q.stamp = skb->tstamp;
+	if (frag_type == LOWPAN_DISPATCH_FRAG1)
+		fq->q.flags |= INET_FRAG_FIRST_IN;
+
+	fq->q.meat += skb->len;
+	add_frag_mem_limit(fq->q.fqdir, skb->truesize);
+
+	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 = lowpan_frag_reasm(fq, skb, prev_tail, ldev);
+		skb->_skb_refdst = orefdst;
+		return res;
+	}
+	skb_dst_drop(skb);
+
+	return -1;
+err:
+	kfree_skb(skb);
+	return -1;
+}
+
+/*	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 lowpan_frag_reasm(struct lowpan_frag_queue *fq, struct sk_buff *skb,
+			     struct sk_buff *prev_tail, struct net_device *ldev)
+{
+	void *reasm_data;
+
+	inet_frag_kill(&fq->q);
+
+	reasm_data = inet_frag_reasm_prepare(&fq->q, skb, prev_tail);
+	if (!reasm_data)
+		goto out_oom;
+	inet_frag_reasm_finish(&fq->q, skb, reasm_data, false);
+
+	skb->dev = ldev;
+	skb->tstamp = fq->q.stamp;
+	fq->q.rb_fragments = RB_ROOT;
+	fq->q.fragments_tail = NULL;
+	fq->q.last_run_head = NULL;
+
+	return 1;
+out_oom:
+	net_dbg_ratelimited("lowpan_frag_reasm: no memory for reassembly\n");
+	return -1;
+}
+
+static int lowpan_frag_rx_handlers_result(struct sk_buff *skb,
+					  lowpan_rx_result res)
+{
+	switch (res) {
+	case RX_QUEUED:
+		return NET_RX_SUCCESS;
+	case RX_CONTINUE:
+		/* nobody cared about this packet */
+		net_warn_ratelimited("%s: received unknown dispatch\n",
+				     __func__);
+
+		fallthrough;
+	default:
+		/* all others failure */
+		return NET_RX_DROP;
+	}
+}
+
+static lowpan_rx_result lowpan_frag_rx_h_iphc(struct sk_buff *skb)
+{
+	int ret;
+
+	if (!lowpan_is_iphc(*skb_network_header(skb)))
+		return RX_CONTINUE;
+
+	ret = lowpan_iphc_decompress(skb);
+	if (ret < 0)
+		return RX_DROP;
+
+	return RX_QUEUED;
+}
+
+static int lowpan_invoke_frag_rx_handlers(struct sk_buff *skb)
+{
+	lowpan_rx_result res;
+
+#define CALL_RXH(rxh)			\
+	do {				\
+		res = rxh(skb);	\
+		if (res != RX_CONTINUE)	\
+			goto rxh_next;	\
+	} while (0)
+
+	/* likely at first */
+	CALL_RXH(lowpan_frag_rx_h_iphc);
+	CALL_RXH(lowpan_rx_h_ipv6);
+
+rxh_next:
+	return lowpan_frag_rx_handlers_result(skb, res);
+#undef CALL_RXH
+}
+
+#define LOWPAN_FRAG_DGRAM_SIZE_HIGH_MASK	0x07
+#define LOWPAN_FRAG_DGRAM_SIZE_HIGH_SHIFT	8
+
+static int lowpan_get_cb(struct sk_buff *skb, u8 frag_type,
+			 struct lowpan_802154_cb *cb)
+{
+	bool fail;
+	u8 high = 0, low = 0;
+	__be16 d_tag = 0;
+
+	fail = lowpan_fetch_skb(skb, &high, 1);
+	fail |= lowpan_fetch_skb(skb, &low, 1);
+	/* remove the dispatch value and use first three bits as high value
+	 * for the datagram size
+	 */
+	cb->d_size = (high & LOWPAN_FRAG_DGRAM_SIZE_HIGH_MASK) <<
+		LOWPAN_FRAG_DGRAM_SIZE_HIGH_SHIFT | low;
+	fail |= lowpan_fetch_skb(skb, &d_tag, 2);
+	cb->d_tag = ntohs(d_tag);
+
+	if (frag_type == LOWPAN_DISPATCH_FRAGN) {
+		fail |= lowpan_fetch_skb(skb, &cb->d_offset, 1);
+	} else {
+		skb_reset_network_header(skb);
+		cb->d_offset = 0;
+		/* check if datagram_size has ipv6hdr on FRAG1 */
+		fail |= cb->d_size < sizeof(struct ipv6hdr);
+		/* check if we can dereference the dispatch value */
+		fail |= !skb->len;
+	}
+
+	if (unlikely(fail))
+		return -EIO;
+
+	return 0;
+}
+
+int lowpan_frag_rcv(struct sk_buff *skb, u8 frag_type)
+{
+	struct lowpan_frag_queue *fq;
+	struct net *net = dev_net(skb->dev);
+	struct lowpan_802154_cb *cb = lowpan_802154_cb(skb);
+	struct ieee802154_hdr hdr = {};
+	int err;
+
+	if (ieee802154_hdr_peek_addrs(skb, &hdr) < 0)
+		goto err;
+
+	err = lowpan_get_cb(skb, frag_type, cb);
+	if (err < 0)
+		goto err;
+
+	if (frag_type == LOWPAN_DISPATCH_FRAG1) {
+		err = lowpan_invoke_frag_rx_handlers(skb);
+		if (err == NET_RX_DROP)
+			goto err;
+	}
+
+	if (cb->d_size > IPV6_MIN_MTU) {
+		net_warn_ratelimited("lowpan_frag_rcv: datagram size exceeds MTU\n");
+		goto err;
+	}
+
+	fq = fq_find(net, cb, &hdr.source, &hdr.dest);
+	if (fq != NULL) {
+		int ret;
+
+		spin_lock(&fq->q.lock);
+		ret = lowpan_frag_queue(fq, skb, frag_type);
+		spin_unlock(&fq->q.lock);
+
+		inet_frag_put(&fq->q);
+		return ret;
+	}
+
+err:
+	kfree_skb(skb);
+	return -1;
+}
+
+#ifdef CONFIG_SYSCTL
+
+static struct ctl_table lowpan_frags_ns_ctl_table[] = {
+	{
+		.procname	= "6lowpanfrag_high_thresh",
+		.maxlen		= sizeof(unsigned long),
+		.mode		= 0644,
+		.proc_handler	= proc_doulongvec_minmax,
+	},
+	{
+		.procname	= "6lowpanfrag_low_thresh",
+		.maxlen		= sizeof(unsigned long),
+		.mode		= 0644,
+		.proc_handler	= proc_doulongvec_minmax,
+	},
+	{
+		.procname	= "6lowpanfrag_time",
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{ }
+};
+
+/* secret interval has been deprecated */
+static int lowpan_frags_secret_interval_unused;
+static struct ctl_table lowpan_frags_ctl_table[] = {
+	{
+		.procname	= "6lowpanfrag_secret_interval",
+		.data		= &lowpan_frags_secret_interval_unused,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{ }
+};
+
+static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
+{
+	struct ctl_table *table;
+	struct ctl_table_header *hdr;
+	struct netns_ieee802154_lowpan *ieee802154_lowpan =
+		net_ieee802154_lowpan(net);
+
+	table = lowpan_frags_ns_ctl_table;
+	if (!net_eq(net, &init_net)) {
+		table = kmemdup(table, sizeof(lowpan_frags_ns_ctl_table),
+				GFP_KERNEL);
+		if (table == NULL)
+			goto err_alloc;
+
+		/* Don't export sysctls to unprivileged users */
+		if (net->user_ns != &init_user_ns)
+			table[0].procname = NULL;
+	}
+
+	table[0].data	= &ieee802154_lowpan->fqdir->high_thresh;
+	table[0].extra1	= &ieee802154_lowpan->fqdir->low_thresh;
+	table[1].data	= &ieee802154_lowpan->fqdir->low_thresh;
+	table[1].extra2	= &ieee802154_lowpan->fqdir->high_thresh;
+	table[2].data	= &ieee802154_lowpan->fqdir->timeout;
+
+	hdr = register_net_sysctl(net, "net/ieee802154/6lowpan", table);
+	if (hdr == NULL)
+		goto err_reg;
+
+	ieee802154_lowpan->sysctl.frags_hdr = hdr;
+	return 0;
+
+err_reg:
+	if (!net_eq(net, &init_net))
+		kfree(table);
+err_alloc:
+	return -ENOMEM;
+}
+
+static void __net_exit lowpan_frags_ns_sysctl_unregister(struct net *net)
+{
+	struct ctl_table *table;
+	struct netns_ieee802154_lowpan *ieee802154_lowpan =
+		net_ieee802154_lowpan(net);
+
+	table = ieee802154_lowpan->sysctl.frags_hdr->ctl_table_arg;
+	unregister_net_sysctl_table(ieee802154_lowpan->sysctl.frags_hdr);
+	if (!net_eq(net, &init_net))
+		kfree(table);
+}
+
+static struct ctl_table_header *lowpan_ctl_header;
+
+static int __init lowpan_frags_sysctl_register(void)
+{
+	lowpan_ctl_header = register_net_sysctl(&init_net,
+						"net/ieee802154/6lowpan",
+						lowpan_frags_ctl_table);
+	return lowpan_ctl_header == NULL ? -ENOMEM : 0;
+}
+
+static void lowpan_frags_sysctl_unregister(void)
+{
+	unregister_net_sysctl_table(lowpan_ctl_header);
+}
+#else
+static inline int lowpan_frags_ns_sysctl_register(struct net *net)
+{
+	return 0;
+}
+
+static inline void lowpan_frags_ns_sysctl_unregister(struct net *net)
+{
+}
+
+static inline int __init lowpan_frags_sysctl_register(void)
+{
+	return 0;
+}
+
+static inline void lowpan_frags_sysctl_unregister(void)
+{
+}
+#endif
+
+static int __net_init lowpan_frags_init_net(struct net *net)
+{
+	struct netns_ieee802154_lowpan *ieee802154_lowpan =
+		net_ieee802154_lowpan(net);
+	int res;
+
+
+	res = fqdir_init(&ieee802154_lowpan->fqdir, &lowpan_frags, net);
+	if (res < 0)
+		return res;
+
+	ieee802154_lowpan->fqdir->high_thresh = IPV6_FRAG_HIGH_THRESH;
+	ieee802154_lowpan->fqdir->low_thresh = IPV6_FRAG_LOW_THRESH;
+	ieee802154_lowpan->fqdir->timeout = IPV6_FRAG_TIMEOUT;
+
+	res = lowpan_frags_ns_sysctl_register(net);
+	if (res < 0)
+		fqdir_exit(ieee802154_lowpan->fqdir);
+	return res;
+}
+
+static void __net_exit lowpan_frags_pre_exit_net(struct net *net)
+{
+	struct netns_ieee802154_lowpan *ieee802154_lowpan =
+		net_ieee802154_lowpan(net);
+
+	fqdir_pre_exit(ieee802154_lowpan->fqdir);
+}
+
+static void __net_exit lowpan_frags_exit_net(struct net *net)
+{
+	struct netns_ieee802154_lowpan *ieee802154_lowpan =
+		net_ieee802154_lowpan(net);
+
+	lowpan_frags_ns_sysctl_unregister(net);
+	fqdir_exit(ieee802154_lowpan->fqdir);
+}
+
+static struct pernet_operations lowpan_frags_ops = {
+	.init		= lowpan_frags_init_net,
+	.pre_exit	= lowpan_frags_pre_exit_net,
+	.exit		= lowpan_frags_exit_net,
+};
+
+static u32 lowpan_key_hashfn(const void *data, u32 len, u32 seed)
+{
+	return jhash2(data,
+		      sizeof(struct frag_lowpan_compare_key) / sizeof(u32), seed);
+}
+
+static u32 lowpan_obj_hashfn(const void *data, u32 len, u32 seed)
+{
+	const struct inet_frag_queue *fq = data;
+
+	return jhash2((const u32 *)&fq->key,
+		      sizeof(struct frag_lowpan_compare_key) / sizeof(u32), seed);
+}
+
+static int lowpan_obj_cmpfn(struct rhashtable_compare_arg *arg, const void *ptr)
+{
+	const struct frag_lowpan_compare_key *key = arg->key;
+	const struct inet_frag_queue *fq = ptr;
+
+	return !!memcmp(&fq->key, key, sizeof(*key));
+}
+
+static const struct rhashtable_params lowpan_rhash_params = {
+	.head_offset		= offsetof(struct inet_frag_queue, node),
+	.hashfn			= lowpan_key_hashfn,
+	.obj_hashfn		= lowpan_obj_hashfn,
+	.obj_cmpfn		= lowpan_obj_cmpfn,
+	.automatic_shrinking	= true,
+};
+
+int __init lowpan_net_frag_init(void)
+{
+	int ret;
+
+	lowpan_frags.constructor = lowpan_frag_init;
+	lowpan_frags.destructor = NULL;
+	lowpan_frags.qsize = sizeof(struct frag_queue);
+	lowpan_frags.frag_expire = lowpan_frag_expire;
+	lowpan_frags.frags_cache_name = lowpan_frags_cache_name;
+	lowpan_frags.rhash_params = lowpan_rhash_params;
+	ret = inet_frags_init(&lowpan_frags);
+	if (ret)
+		goto out;
+
+	ret = lowpan_frags_sysctl_register();
+	if (ret)
+		goto err_sysctl;
+
+	ret = register_pernet_subsys(&lowpan_frags_ops);
+	if (ret)
+		goto err_pernet;
+out:
+	return ret;
+err_pernet:
+	lowpan_frags_sysctl_unregister();
+err_sysctl:
+	inet_frags_fini(&lowpan_frags);
+	return ret;
+}
+
+void lowpan_net_frag_exit(void)
+{
+	lowpan_frags_sysctl_unregister();
+	unregister_pernet_subsys(&lowpan_frags_ops);
+	inet_frags_fini(&lowpan_frags);
+}