6lowpan: iphc: fix handling of link-local compression

This patch fixes handling in case of link-local address compression. A
IPv6 link-local address is defined as fe80::/10 prefix which is also
what ipv6_addr_type checks for link-local addresses.

But IPHC compression for link-local addresses are for fe80::/64 types
only. This patch adds additional checks for zero padded bits in case of
link-local address compression to match on a fe80::/64 address only.

Signed-off-by: Alexander Aring <aar@pengutronix.de>
Acked-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
Reviewed-by: Stefan Schmidt <stefan@osg.samsung.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

1 files changed, 9 insertions, 2 deletions

diff --git a/net/6lowpan/iphc.c b/net/6lowpan/iphc.c
index 99bb22aea346..68c80f3c9add 100644
--- a/net/6lowpan/iphc.c
+++ b/net/6lowpan/iphc.c
@@ -148,6 +148,11 @@
          (((a)->s6_addr16[6]) == 0) &&          \
          (((a)->s6_addr[14]) == 0))
 
+#define lowpan_is_linklocal_zero_padded(a)      \
+        (!(hdr->saddr.s6_addr[1] & 0x3f) &&     \
+         !hdr->saddr.s6_addr16[1] &&            \
+         !hdr->saddr.s6_addr32[1])
+
 #define LOWPAN_IPHC_CID_DCI(cid)        (cid & 0x0f)
 #define LOWPAN_IPHC_CID_SCI(cid)        ((cid & 0xf0) >> 4)
 
@@ -1101,7 +1106,8 @@ int lowpan_header_compress(struct sk_buff *skb, const struct net_device *dev,
                                                           true);
                         iphc1 |= LOWPAN_IPHC_SAC;
                 } else {
-                        if (ipv6_saddr_type & IPV6_ADDR_LINKLOCAL) {
+                        if (ipv6_saddr_type & IPV6_ADDR_LINKLOCAL &&
+                            lowpan_is_linklocal_zero_padded(hdr->saddr)) {
                                 iphc1 |= lowpan_compress_addr_64(&hc_ptr,
                                                                  &hdr->saddr,
                                                                  saddr, true);
@@ -1135,7 +1141,8 @@ int lowpan_header_compress(struct sk_buff *skb, const struct net_device *dev,
                                                           false);
                         iphc1 |= LOWPAN_IPHC_DAC;
                 } else {
-                        if (ipv6_daddr_type & IPV6_ADDR_LINKLOCAL) {
+                        if (ipv6_daddr_type & IPV6_ADDR_LINKLOCAL &&
+                            lowpan_is_linklocal_zero_padded(hdr->daddr)) {
                                 iphc1 |= lowpan_compress_addr_64(&hc_ptr,
                                                                  &hdr->daddr,
                                                                  daddr, false);