netdev - Re: [PATCH iproute2] tc: fix ipv6 filter selector attribute for some prefix lengths

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Date:   Wed, 27 Sep 2017 09:26:34 +0100
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     Yulia Kartseva <yulia.kartseva@...il.com>
Cc:     netdev@...r.kernel.org, shemminger@...ux-foundation.org
Subject: Re: [PATCH iproute2] tc: fix ipv6 filter selector attribute for
 some prefix lengths

On Mon, 25 Sep 2017 11:12:38 -0700
Yulia Kartseva <yulia.kartseva@...il.com> wrote:

> Wrong TCA_U32_SEL attribute packing if prefixLen AND 0x1f equals 0x1f.
> These are  /31, /63, /95 and /127 prefix lengths.
> 
> Example:
> # tc filter add dev eth0 protocol ipv6 parent b: prio 2307 u32 match
> ip6 dst face:b00f::/31
> # tc filter show dev eth0
> filter parent b: protocol ipv6 pref 2307 u32
> filter parent b: protocol ipv6 pref 2307 u32 fh 800: ht divisor 1
> filter parent b: protocol ipv6 pref 2307 u32 fh 800::800 order 2048
> key ht 800 bkt 0
>   match faceb00f/ffffffff at 24
> 
> 
> The correct match would be "faceb00e/fffffffe": don't count the last
> bit of the 4th byte as the network prefix. With fix:
> 
> # tc filter show dev eth0
> filter parent b: protocol ipv6 pref 2307 u32
> filter parent b: protocol ipv6 pref 2307 u32 fh 800: ht divisor 1
> filter parent b: protocol ipv6 pref 2307 u32 fh 800::800 order 2048
> key ht 800 bkt 0
>   match faceb00e/fffffffe at 24
> 
>  tc/f_u32.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/tc/f_u32.c b/tc/f_u32.c
> index 5815be9..14b9588 100644
> --- a/tc/f_u32.c
> +++ b/tc/f_u32.c
> @@ -385,8 +385,7 @@ static int parse_ip6_addr(int *argc_p, char ***argv_p,
> 
>   plen = addr.bitlen;
>   for (i = 0; i < plen; i += 32) {
> - /* if (((i + 31) & ~0x1F) <= plen) { */
> - if (i + 31 <= plen) {
> + if (i + 31 < plen) {
>   res = pack_key(sel, addr.data[i / 32],
>         0xFFFFFFFF, off + 4 * (i / 32), offmask);
>   if (res < 0)

This patch looks correct, but will not apply cleanly because
the mail system that you submitted it with is removing whitespace.
If possible use a different client, or send as an attachment.