Jean-Michel DILLY wrote:
> Hi,
>
> Here is the signed-off patch.
>
> Signed-off-by: Jean-Michel DILLY <jm@xxxxxxxx>
> ---
> diff --git a/ip6t_NPT.c b/linux-3.8-rc4/net/ipv6/netfilter/ip6t_NPT.c
> index 787748b..29ef720 100644
> --- a/ip6t_NPT.c
> +++ b/linux-3.8-rc4/net/ipv6/netfilter/ip6t_NPT.c
> @@ -14,24 +14,44 @@
> #include <linux/netfilter_ipv6/ip6t_NPT.h>
> #include <linux/netfilter/x_tables.h>
>
> +static __sum16 csum16_add(__sum16 a, __sum16 b)
> +{
> + __u16 result;
> +
> + result = (__force __u16) a + (__force __u16) b;
> + result += result < (__force __u16)b;
> +
> +
> + return (__force __sum16) result;
> +}
> +
> +static __sum16 csum16_complement(__sum16 a)
> +{
> + return (__force __sum16)(0xffff - (__force u16)a);
> +}
> +
> +static __sum16 csum16_sub(__sum16 a, __sum16 b)
> +{
> + return csum16_add(a, csum16_complement(b));
> +}
>
> static int ip6t_npt_checkentry(const struct xt_tgchk_param *par)
> {
> struct ip6t_npt_tginfo *npt = par->targinfo;
> - __wsum src_sum = 0, dst_sum = 0;
> + __sum16 src_sum = 0, dst_sum = 0;
> unsigned int i;
>
> if (npt->src_pfx_len > 64 || npt->dst_pfx_len > 64)
> return -EINVAL;
>
> for (i = 0; i < ARRAY_SIZE(npt->src_pfx.in6.s6_addr16); i++) {
> - src_sum = csum_add(src_sum,
> - (__force __wsum)npt->src_pfx.in6.s6_addr16[i]);
> - dst_sum = csum_add(dst_sum,
> - (__force __wsum)npt->dst_pfx.in6.s6_addr16[i]);
> + src_sum = csum16_add(src_sum,
> + (__force __sum16)npt->src_pfx.in6.s6_addr16[i]);
> + dst_sum = csum16_add(dst_sum,
> + (__force __sum16)npt->dst_pfx.in6.s6_addr16[i]);
> }
>
> - npt->adjustment = (__force __sum16) csum_sub(src_sum, dst_sum);
> + npt->adjustment = csum16_sub(src_sum, dst_sum);
> return 0;
> }
>
> @@ -67,8 +87,8 @@ static bool ip6t_npt_map_pfx(const struct ip6t_npt_tginfo *npt,
> return false;
> }
>
> - sum = (__force __sum16) csum_add((__force __wsum)addr->s6_addr16[idx],
> - npt->adjustment);
> + sum = csum16_add((__force __sum16)addr->s6_addr16[idx],
> + npt->adjustment);
> if (sum == CSUM_MANGLED_0)
> sum = 0;
> *(__force __sum16 *)&addr->s6_addr16[idx] = sum;
>
> Le 24 janv. 2013 à 23:49, Florian Westphal a écrit :
>
>> Jean-Michel DILLY <jm@xxxxxxxx> wrote:
>>> Hi all,
>>> This patch doesn't work as expected. I tried with few IP and each time 0x0100 were missing. csum_add seems buggy too.
>>> I have reimplemented csum16s functions with the Ulrich's fix. It seems to work now.
>>> I'm a noob, so I guess someone will propose a better patch for this.
>>
>> We can't use csum_add after all, patch looks correct.
>>
>> Can you re-send with proper Signoff?
>>
>> [ carry detection breaks on overflow, e.g. a==1 and b=0xffff yields
>> 0 for csum_add (65536 < 1) and 1 for csum16_add (0 < 1) ]
Well... why do you fill npt->adjustment?
I think we can do checksumming in ip6t_npt_map_pfx()
with csum_partial(), csum_block_add()/csum_block_sub() and
csum_fold().
--yoshfuji
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