2016-03-16 12:52:41

by Alexander Aring

Subject: [PATCH bluetooth-next] 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 <[email protected]>
---
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,
&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);
--
2.7.3

2016-03-16 15:44:14

by Stefan Schmidt

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

Hello.

On 16/03/16 13:52, 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.
>
> Signed-off-by: Alexander Aring <[email protected]>
> ---
> 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,
> &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);

Nicely spotted.

Reviewed-by: Stefan Schmidt <[email protected]>

regards
Stefan Schmidt

2016-03-16 13:39:53

by Jukka Rissanen

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

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 <[email protected]>



> Signed-off-by: Alexander Aring <[email protected]>
> ---
>  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

2016-04-08 17:32:17

by Marcel Holtmann

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

Hi Alex,

> 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 <[email protected]>
> ---
> net/6lowpan/iphc.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel