On 02/16/2014 01:27 PM, Patrick McHardy wrote: > On Sun, Feb 16, 2014 at 01:09:43PM +0100, Nikolay Aleksandrov wrote: >> On 02/16/2014 01:07 PM, Patrick McHardy wrote: >>> On Sun, Feb 16, 2014 at 12:54:40PM +0100, Nikolay Aleksandrov wrote: >>>> Add a check if payload's offset is a power of 2 when selecting ops. >>>> The fast ops were meant for well aligned offsets, also this fixes a >>>> small bug when using unaligned offset and length of 3 which causes >>>> only 1 byte to be loaded because the fast ops are chosen. >>>> >>>> Signed-off-by: Nikolay Aleksandrov <nikolay@xxxxxxxxxx> >>>> --- >>>> I broke the line since it was >80 chars. >>>> This patch applies to Dave's -net tree. >>>> >>>> net/netfilter/nft_payload.c | 4 +++- >>>> 1 file changed, 3 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/net/netfilter/nft_payload.c b/net/netfilter/nft_payload.c >>>> index a2aeb31..15a3dcb 100644 >>>> --- a/net/netfilter/nft_payload.c >>>> +++ b/net/netfilter/nft_payload.c >>>> @@ -135,7 +135,9 @@ nft_payload_select_ops(const struct nft_ctx *ctx, >>>> if (len == 0 || len > FIELD_SIZEOF(struct nft_data, data)) >>>> return ERR_PTR(-EINVAL); >>>> >>>> - if (len <= 4 && IS_ALIGNED(offset, len) && base != NFT_PAYLOAD_LL_HEADER) >>>> + if (len <= 4 && IS_ALIGNED(offset, len) && >>>> + base != NFT_PAYLOAD_LL_HEADER && >>>> + !(offset & (offset - 1))) >>> >>> Small cosmetic note: we have is_power_of_2(), which does exactly this. >>> >> I didn't choose is_power_of_2 because it also checks if x is != 0, so I >> thought we can allow for 0 offset with the fast ops. > > Sorry for not noticing before, but I'd propose to check length for power > of two. We're trying to determine whether the load is well aligned. > hehe, I was wondering why the offset but decided to just go with it, should've asked. Okay, going for v3 I guess. >> >>> Also I think the more logical order would be: >>> >>> len <= 4 && is_power_of_2 && IS_ALIGNED && base ... >>> >> Okay :-) >> >>>> return &nft_payload_fast_ops; >>>> else >>>> return &nft_payload_ops; >>>> -- >>>> 1.8.4.2 -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
