Merge branch '6lowpan'

Tony Cheneau says:

====================
This patchset fixes serious bugs within the 6LoWPAN modules. I wrote a script
(available at [1]) to prove the issues are real.  One can try and see that
without these patches, most of the test fail (e.g. packet dropped by the
receiver or node crashing). With all patches applied, all tests succeed. The
tests themselves are very basic: sending ICMP packets, sending UDP packets,
sending TCP packets, varying size of the packets. This actually triggers some
6LoWPAN specific code, namely fragmentation, packet reassembly and header
compression.

This code passed the checkpatch.pl tool with a few warnings, that I believe
are OK. It should apply cleanly on the latest net-next.

[1]: https://github.com/tcheneau/linux802154-regression-tests
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ieee802154/6lowpan.c

@@ -104,6 +104,7 @@ static const u8 lowpan_llprefix[] = {0xfe, 0x80};
 struct lowpan_dev_info {
 	struct net_device	*real_dev; /* real WPAN device ptr */
 	struct mutex		dev_list_mtx; /* mutex for list ops */
+	unsigned short fragment_tag;
 };
 
 struct lowpan_dev_record {
@@ -120,7 +121,6 @@ struct lowpan_fragment {
 	struct list_head	list;		/* fragments list */
 };
 
-static unsigned short fragment_tag;
 static LIST_HEAD(lowpan_fragments);
 static DEFINE_SPINLOCK(flist_lock);
 
@@ -284,6 +284,9 @@ lowpan_compress_udp_header(u8 **hc06_ptr, struct sk_buff *skb)
 	/* checksum is always inline */
 	memcpy(*hc06_ptr, &uh->check, 2);
 	*hc06_ptr += 2;
+
+	/* skip the UDP header */
+	skb_pull(skb, sizeof(struct udphdr));
 }
 
 static inline int lowpan_fetch_skb_u8(struct sk_buff *skb, u8 *val)
@@ -309,9 +312,8 @@ static inline int lowpan_fetch_skb_u16(struct sk_buff *skb, u16 *val)
 }
 
 static int
-lowpan_uncompress_udp_header(struct sk_buff *skb)
+lowpan_uncompress_udp_header(struct sk_buff *skb, struct udphdr *uh)
 {
-	struct udphdr *uh = udp_hdr(skb);
 	u8 tmp;
 
 	if (!uh)
@@ -358,6 +360,14 @@ lowpan_uncompress_udp_header(struct sk_buff *skb)
 		/* copy checksum */
 		memcpy(&uh->check, &skb->data[0], 2);
 		skb_pull(skb, 2);
+
+		/*
+		 * UDP lenght needs to be infered from the lower layers
+		 * here, we obtain the hint from the remaining size of the
+		 * frame
+		 */
+		uh->len = htons(skb->len + sizeof(struct udphdr));
+		pr_debug("uncompressed UDP length: src = %d", uh->len);
 	} else {
 		pr_debug("ERROR: unsupported NH format\n");
 		goto err;
@@ -572,17 +582,31 @@ static int lowpan_header_create(struct sk_buff *skb,
 	 * this isn't implemented in mainline yet, so currently we assign 0xff
 	 */
 	{
+		mac_cb(skb)->flags = IEEE802154_FC_TYPE_DATA;
+		mac_cb(skb)->seq = ieee802154_mlme_ops(dev)->get_dsn(dev);
+
 		/* prepare wpan address data */
 		sa.addr_type = IEEE802154_ADDR_LONG;
-		sa.pan_id = 0xff;
+		sa.pan_id = ieee802154_mlme_ops(dev)->get_pan_id(dev);
 
-		da.addr_type = IEEE802154_ADDR_LONG;
-		da.pan_id = 0xff;
+		memcpy(&(sa.hwaddr), saddr, 8);
+		/* intra-PAN communications */
+		da.pan_id = ieee802154_mlme_ops(dev)->get_pan_id(dev);
 
+		/*
+		 * if the destination address is the broadcast address, use the
+		 * corresponding short address
+		 */
+		if (lowpan_is_addr_broadcast(daddr)) {
+			da.addr_type = IEEE802154_ADDR_SHORT;
+			da.short_addr = IEEE802154_ADDR_BROADCAST;
+		} else {
+			da.addr_type = IEEE802154_ADDR_LONG;
 			memcpy(&(da.hwaddr), daddr, 8);
-		memcpy(&(sa.hwaddr), saddr, 8);
 
-		mac_cb(skb)->flags = IEEE802154_FC_TYPE_DATA;
+			/* request acknowledgment */
+			mac_cb(skb)->flags |= MAC_CB_FLAG_ACKREQ;
+		}
 
 		return dev_hard_header(skb, lowpan_dev_info(dev)->real_dev,
 				type, (void *)&da, (void *)&sa, skb->len);
@@ -650,7 +674,7 @@ static void lowpan_fragment_timer_expired(unsigned long entry_addr)
 }
 
 static struct lowpan_fragment *
-lowpan_alloc_new_frame(struct sk_buff *skb, u8 len, u16 tag)
+lowpan_alloc_new_frame(struct sk_buff *skb, u16 len, u16 tag)
 {
 	struct lowpan_fragment *frame;
 
@@ -720,7 +744,7 @@ lowpan_process_data(struct sk_buff *skb)
 	{
 		struct lowpan_fragment *frame;
 		/* slen stores the rightmost 8 bits of the 11 bits length */
-		u8 slen, offset;
+		u8 slen, offset = 0;
 		u16 len, tag;
 		bool found = false;
 
@@ -731,6 +755,18 @@ lowpan_process_data(struct sk_buff *skb)
 		/* adds the 3 MSB to the 8 LSB to retrieve the 11 bits length */
 		len = ((iphc0 & 7) << 8) | slen;
 
+		if ((iphc0 & LOWPAN_DISPATCH_MASK) == LOWPAN_DISPATCH_FRAG1) {
+			pr_debug("%s received a FRAG1 packet (tag: %d, "
+				 "size of the entire IP packet: %d)",
+				 __func__, tag, len);
+		} else { /* FRAGN */
+			if (lowpan_fetch_skb_u8(skb, &offset))
+				goto unlock_and_drop;
+			pr_debug("%s received a FRAGN packet (tag: %d, "
+				 "size of the entire IP packet: %d, "
+				 "offset: %d)", __func__, tag, len, offset * 8);
+		}
+
 		/*
 		 * check if frame assembling with the same tag is
 		 * already in progress
@@ -745,17 +781,13 @@ lowpan_process_data(struct sk_buff *skb)
 
 		/* alloc new frame structure */
 		if (!found) {
+			pr_debug("%s first fragment received for tag %d, "
+				 "begin packet reassembly", __func__, tag);
 			frame = lowpan_alloc_new_frame(skb, len, tag);
 			if (!frame)
 				goto unlock_and_drop;
 		}
 
-		if ((iphc0 & LOWPAN_DISPATCH_MASK) == LOWPAN_DISPATCH_FRAG1)
-			goto unlock_and_drop;
-
-		if (lowpan_fetch_skb_u8(skb, &offset)) /* fetch offset */
-			goto unlock_and_drop;
-
 		/* if payload fits buffer, copy it */
 		if (likely((offset * 8 + skb->len) <= frame->length))
 			skb_copy_to_linear_data_offset(frame->skb, offset * 8,
@@ -773,6 +805,9 @@ lowpan_process_data(struct sk_buff *skb)
 			list_del(&frame->list);
 			spin_unlock_bh(&flist_lock);
 
+			pr_debug("%s successfully reassembled fragment "
+				 "(tag %d)", __func__, tag);
+
 			dev_kfree_skb(skb);
 			skb = frame->skb;
 			kfree(frame);
@@ -918,10 +953,35 @@ lowpan_process_data(struct sk_buff *skb)
 	}
 
 	/* UDP data uncompression */
-	if (iphc0 & LOWPAN_IPHC_NH_C)
-		if (lowpan_uncompress_udp_header(skb))
+	if (iphc0 & LOWPAN_IPHC_NH_C) {
+		struct udphdr uh;
+		struct sk_buff *new;
+		if (lowpan_uncompress_udp_header(skb, &uh))
 			goto drop;
 
+		/*
+		 * replace the compressed UDP head by the uncompressed UDP
+		 * header
+		 */
+		new = skb_copy_expand(skb, sizeof(struct udphdr),
+				      skb_tailroom(skb), GFP_ATOMIC);
+		kfree_skb(skb);
+
+		if (!new)
+			return -ENOMEM;
+
+		skb = new;
+
+		skb_push(skb, sizeof(struct udphdr));
+		skb_reset_transport_header(skb);
+		skb_copy_to_linear_data(skb, &uh, sizeof(struct udphdr));
+
+		lowpan_raw_dump_table(__func__, "raw UDP header dump",
+				      (u8 *)&uh, sizeof(uh));
+
+		hdr.nexthdr = UIP_PROTO_UDP;
+	}
+
 	/* Not fragmented package */
 	hdr.payload_len = htons(skb->len);
 
@@ -969,13 +1029,13 @@ static int lowpan_get_mac_header_length(struct sk_buff *skb)
 
 static int
 lowpan_fragment_xmit(struct sk_buff *skb, u8 *head,
-			int mlen, int plen, int offset)
+			int mlen, int plen, int offset, int type)
 {
 	struct sk_buff *frag;
 	int hlen, ret;
 
-	/* if payload length is zero, therefore it's a first fragment */
-	hlen = (plen == 0 ? LOWPAN_FRAG1_HEAD_SIZE :  LOWPAN_FRAGN_HEAD_SIZE);
+	hlen = (type == LOWPAN_DISPATCH_FRAG1) ?
+			LOWPAN_FRAG1_HEAD_SIZE : LOWPAN_FRAGN_HEAD_SIZE;
 
 	lowpan_raw_dump_inline(__func__, "6lowpan fragment header", head, hlen);
 
@@ -1003,14 +1063,14 @@ lowpan_fragment_xmit(struct sk_buff *skb, u8 *head,
 }
 
 static int
-lowpan_skb_fragmentation(struct sk_buff *skb)
+lowpan_skb_fragmentation(struct sk_buff *skb, struct net_device *dev)
 {
 	int  err, header_length, payload_length, tag, offset = 0;
 	u8 head[5];
 
 	header_length = lowpan_get_mac_header_length(skb);
 	payload_length = skb->len - header_length;
-	tag = fragment_tag++;
+	tag = lowpan_dev_info(dev)->fragment_tag++;
 
 	/* first fragment header */
 	head[0] = LOWPAN_DISPATCH_FRAG1 | ((payload_length >> 8) & 0x7);
@@ -1018,7 +1078,16 @@ lowpan_skb_fragmentation(struct sk_buff *skb)
 	head[2] = tag >> 8;
 	head[3] = tag & 0xff;
 
-	err = lowpan_fragment_xmit(skb, head, header_length, 0, 0);
+	err = lowpan_fragment_xmit(skb, head, header_length, LOWPAN_FRAG_SIZE,
+				   0, LOWPAN_DISPATCH_FRAG1);
+
+	if (err) {
+		pr_debug("%s unable to send FRAG1 packet (tag: %d)",
+			 __func__, tag);
+		goto exit;
+	}
+
+	offset = LOWPAN_FRAG_SIZE;
 
 	/* next fragment header */
 	head[0] &= ~LOWPAN_DISPATCH_FRAG1;
@@ -1033,10 +1102,17 @@ lowpan_skb_fragmentation(struct sk_buff *skb)
 			len = payload_length - offset;
 
 		err = lowpan_fragment_xmit(skb, head, header_length,
-							len, offset);
+					   len, offset, LOWPAN_DISPATCH_FRAGN);
+		if (err) {
+			pr_debug("%s unable to send a subsequent FRAGN packet "
+				 "(tag: %d, offset: %d", __func__, tag, offset);
+			goto exit;
+		}
+
 		offset += len;
 	}
 
+exit:
 	return err;
 }
 
@@ -1059,7 +1135,7 @@ static netdev_tx_t lowpan_xmit(struct sk_buff *skb, struct net_device *dev)
 	}
 
 	pr_debug("frame is too big, fragmentation is needed\n");
-	err = lowpan_skb_fragmentation(skb);
+	err = lowpan_skb_fragmentation(skb, dev);
 error:
 	dev_kfree_skb(skb);
 out:
@@ -1087,6 +1163,12 @@ static u16 lowpan_get_short_addr(const struct net_device *dev)
 	return ieee802154_mlme_ops(real_dev)->get_short_addr(real_dev);
 }
 
+static u8 lowpan_get_dsn(const struct net_device *dev)
+{
+	struct net_device *real_dev = lowpan_dev_info(dev)->real_dev;
+	return ieee802154_mlme_ops(real_dev)->get_dsn(real_dev);
+}
+
 static struct header_ops lowpan_header_ops = {
 	.create	= lowpan_header_create,
 };
@@ -1100,6 +1182,7 @@ static struct ieee802154_mlme_ops lowpan_mlme = {
 	.get_pan_id = lowpan_get_pan_id,
 	.get_phy = lowpan_get_phy,
 	.get_short_addr = lowpan_get_short_addr,
+	.get_dsn = lowpan_get_dsn,
 };
 
 static void lowpan_setup(struct net_device *dev)
@@ -1203,6 +1286,7 @@ static int lowpan_newlink(struct net *src_net, struct net_device *dev,
 		return -ENODEV;
 
 	lowpan_dev_info(dev)->real_dev = real_dev;
+	lowpan_dev_info(dev)->fragment_tag = 0;
 	mutex_init(&lowpan_dev_info(dev)->dev_list_mtx);
 
 	entry = kzalloc(sizeof(struct lowpan_dev_record), GFP_KERNEL);

net/ieee802154/6lowpan.h

@@ -92,9 +92,10 @@
  */
 #define lowpan_is_iid_16_bit_compressable(a)	\
 	((((a)->s6_addr16[4]) == 0) &&		\
-	 (((a)->s6_addr16[5]) == 0) &&		\
-	 (((a)->s6_addr16[6]) == 0) &&		\
-	 ((((a)->s6_addr[14]) & 0x80) == 0))
+	 (((a)->s6_addr[10]) == 0) &&		\
+	 (((a)->s6_addr[11]) == 0xff) &&	\
+	 (((a)->s6_addr[12]) == 0xfe) &&	\
+	 (((a)->s6_addr[13]) == 0))
 
 /* multicast address */
 #define is_addr_mcast(a) (((a)->s6_addr[0]) == 0xFF)

net/mac802154/mac802154.h

@@ -114,5 +114,6 @@ void mac802154_dev_set_ieee_addr(struct net_device *dev);
 u16 mac802154_dev_get_pan_id(const struct net_device *dev);
 void mac802154_dev_set_pan_id(struct net_device *dev, u16 val);
 void mac802154_dev_set_page_channel(struct net_device *dev, u8 page, u8 chan);
+u8 mac802154_dev_get_dsn(const struct net_device *dev);
 
 #endif /* MAC802154_H */

net/mac802154/mac_cmd.c

@@ -73,4 +73,5 @@ struct ieee802154_mlme_ops mac802154_mlme_wpan = {
 	.start_req = mac802154_mlme_start_req,
 	.get_pan_id = mac802154_dev_get_pan_id,
 	.get_short_addr = mac802154_dev_get_short_addr,
+	.get_dsn = mac802154_dev_get_dsn,
 };

net/mac802154/mib.c

@@ -159,6 +159,15 @@ void mac802154_dev_set_pan_id(struct net_device *dev, u16 val)
 	}
 }
 
+u8 mac802154_dev_get_dsn(const struct net_device *dev)
+{
+	struct mac802154_sub_if_data *priv = netdev_priv(dev);
+
+	BUG_ON(dev->type != ARPHRD_IEEE802154);
+
+	return priv->dsn++;
+}
+
 static void phy_chan_notify(struct work_struct *work)
 {
 	struct phy_chan_notify_work *nw = container_of(work,

net/mac802154/wpan.c

@@ -145,6 +145,8 @@ static int mac802154_header_create(struct sk_buff *skb,
 
 	head[pos++] = mac_cb(skb)->seq; /* DSN/BSN */
 	fc = mac_cb_type(skb);
+	if (mac_cb_is_ackreq(skb))
+		fc |= IEEE802154_FC_ACK_REQ;
 
 	if (!saddr) {
 		spin_lock_bh(&priv->mib_lock);