Re: [PATCH v3] extensions: libxt_dccp: Add translation to nft

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Fri, Mar 04, 2016 at 03:31:45AM +0530, Shivani Bhardwaj wrote:
> Add translation for dccp to nftables.
> 
> Full translation of this match awaits the support for --dccp-option.
> 
> Examples:
> 
> $ sudo iptables-translate -A INPUT -p dccp -m dccp --sport 100
> nft add rule ip filter INPUT dccp sport 100 counter
> 
> $ sudo iptables-translate -A INPUT -p dccp -m dccp --dport 100:200
> nft add rule ip filter INPUT dccp dport 100-200 counter
> 
> $ sudo iptables-translate -A INPUT -p dccp -m dccp ! --dport 100
> nft add rule ip filter INPUT dccp dport != 100 counter
> 
> $ sudo iptables-translate -A INPUT -p dccp -m dccp --dport 100 --dccp-types REQUEST,RESPONSE,DATA,ACK,DATAACK,CLOSEREQ,CLOSE,SYNC,SYNCACK
> nft add rule ip filter INPUT dccp dport 100 dccp type {request, response, data, ack, dataack, closereq, close, sync, syncack} counter
> 
> Signed-off-by: Shivani Bhardwaj <shivanib134@gmail.com>
> ---
> Changes in v3:
> 	Return 0 if translation for dccp-option is demanded
> 
> Changes in v2:
>         Fix bugs and remove invalid dccp type
> 
> Following is not added in commit message as it is not translation code
> issue:
> * Since inversion of set is not possible in nftables, using dccp
> with rules like
> ...dccp type != {request, response}..
> * dccp type reset
> is going to throw errors.
> 
>  extensions/libxt_dccp.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 92 insertions(+)
> 
> diff --git a/extensions/libxt_dccp.c b/extensions/libxt_dccp.c
> index a35cabb..0d4f369 100644
> --- a/extensions/libxt_dccp.c
> +++ b/extensions/libxt_dccp.c
> @@ -277,6 +277,97 @@ static void dccp_save(const void *ip, const struct xt_entry_match *match)
>  	}
>  }
>  
> +static const char *const dccp_pkt_types_xlate[] = {
> +	[DCCP_PKT_REQUEST]      = "request",
> +	[DCCP_PKT_RESPONSE]     = "response",
> +	[DCCP_PKT_DATA]         = "data",
> +	[DCCP_PKT_ACK]          = "ack",
> +	[DCCP_PKT_DATAACK]      = "dataack",
> +	[DCCP_PKT_CLOSEREQ]     = "closereq",
> +	[DCCP_PKT_CLOSE]        = "close",
> +	[DCCP_PKT_RESET]        = "reset",
> +	[DCCP_PKT_SYNC]         = "sync",
> +	[DCCP_PKT_SYNCACK]      = "syncack",
> +};
> +
> +static int dccp_type_xlate(const struct xt_dccp_info *einfo,
> +			   struct xt_xlate *xl)
> +{
> +	bool have_type = false, set_need = false;
> +	uint16_t types = einfo->typemask;
> +
> +	if (types & (1 << DCCP_PKT_INVALID))
> +		return 0;
> +
> +	xt_xlate_add(xl, "dccp type%s ", einfo->invflags ? " !=" : "");
> +
> +	if ((types != 0) && !(types == (types & -types))) {
> +		xt_xlate_add(xl, "{");
> +		set_need = true;
> +	}
> +
> +	while (types) {
> +		unsigned int i;
> +
> +		for (i = 0; !(types & (1 << i)); i++);
> +
> +		if (have_type)
> +			xt_xlate_add(xl, ", ");
> +		else
> +			have_type = true;
> +
> +		xt_xlate_add(xl, "%s", dccp_pkt_types_xlate[i]);
> +
> +		types &= ~(1 << i);
> +	}
> +
> +	if (set_need)
> +		xt_xlate_add(xl, "}");
> +
> +	xt_xlate_add(xl, " ");
> +
> +	return 1;
> +}
> +
> +static int dccp_xlate(const struct xt_entry_match *match,
> +		      struct xt_xlate *xl, int numeric)
> +{
> +	const struct xt_dccp_info *einfo =
> +			(const struct xt_dccp_info *)match->data;
> +	int ret = 1;
> +
> +	xt_xlate_add(xl, "dccp ");
> +
> +	if (einfo->flags & XT_DCCP_SRC_PORTS) {
> +		if (einfo->spts[0] != einfo->spts[1])
> +			xt_xlate_add(xl, "sport%s %u-%u ",
> +				     einfo->invflags & XT_DCCP_SRC_PORTS ? " !=" : "",
> +				     einfo->spts[0], einfo->spts[1]);
> +		else
> +			xt_xlate_add(xl, "sport%s %u ",
> +				     einfo->invflags & XT_DCCP_SRC_PORTS ? " !=" : "",
> +				     einfo->spts[0]);
> +	}
> +
> +	if (einfo->flags & XT_DCCP_DEST_PORTS) {
> +		if (einfo->dpts[0] != einfo->dpts[1])
> +			xt_xlate_add(xl, "dport%s %u-%u ",
> +				     einfo->invflags & XT_DCCP_DEST_PORTS ? " !=" : "",
> +				     einfo->dpts[0], einfo->dpts[1]);
> +		else
> +			xt_xlate_add(xl, "dport%s %u ",
> +				     einfo->invflags & XT_DCCP_DEST_PORTS ? " !=" : "",
> +				     einfo->dpts[0]);
> +	}
> +
> +	if (einfo->flags & XT_DCCP_TYPE)
> +		ret = dccp_type_xlate(einfo, xl);
> +
> +	if (einfo->flags & XT_DCCP_OPTION)
> +		ret = 0;

Shouldn't you check fot this XT_DCCP_OPTION in first place?

Or you achieve the same effect? I don't remember how this is behaving
when we already translated many things but just one thing got left
behind.


> +
> +	return ret;
> +}
>  static struct xtables_match dccp_match = {
>  	.name		= "dccp",
>  	.family		= NFPROTO_UNSPEC,
> @@ -288,6 +379,7 @@ static struct xtables_match dccp_match = {
>  	.save		= dccp_save,
>  	.x6_parse	= dccp_parse,
>  	.x6_options	= dccp_opts,
> +	.xlate		= dccp_xlate,
>  };
>  
>  void _init(void)
> -- 
> 1.9.1
> 
> --
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