Re: [PATCH bluetooth-next] 6lowpan: iphc: fix handling of link-local compression

[Jukka Rissanen <jukka.rissanen@linux.intel.com>]

Hi Alex,

On Wed, 2016-03-16 at 13:52 +0100, Alexander Aring wrote:
> 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.

Makes sense although this is probably very unlikely thing to happen.

Acked-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>



> Signed-off-by: Alexander Aring <aar@pengutronix.de>
> ---
>  net/6lowpan/iphc.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/net/6lowpan/iphc.c b/net/6lowpan/iphc.c
> index 99bb22a..68c80f3 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,
>  								 &hd
> r->saddr,
>  								 sad
> dr, 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,
>  								 &hd
> r->daddr,
>  								 dad
> dr, false);


Cheers,
Jukka