LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Florian Westphal <fw@strlen.de>
To: Cole Dishington <Cole.Dishington@alliedtelesis.co.nz>
Cc: pablo@netfilter.org, kadlec@netfilter.org, fw@strlen.de,
	davem@davemloft.net, kuba@kernel.org, shuah@kernel.org,
	linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org,
	coreteam@netfilter.org, netdev@vger.kernel.org,
	linux-kselftest@vger.kernel.org,
	Anthony Lineham <anthony.lineham@alliedtelesis.co.nz>,
	Scott Parlane <scott.parlane@alliedtelesis.co.nz>,
	Blair Steven <blair.steven@alliedtelesis.co.nz>
Subject: Re: [PATCH 2/3] net: netfilter: Add RFC-7597 Section 5.1 PSID support
Date: Fri, 16 Jul 2021 17:18:33 +0200	[thread overview]
Message-ID: <20210716151833.GD9904@breakpoint.cc> (raw)
In-Reply-To: <20210716002742.31078-3-Cole.Dishington@alliedtelesis.co.nz>

Cole Dishington <Cole.Dishington@alliedtelesis.co.nz> wrote:
> diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
> index 7de595ead06a..4a9448684504 100644
> --- a/net/netfilter/nf_nat_core.c
> +++ b/net/netfilter/nf_nat_core.c
> @@ -195,13 +195,36 @@ static bool nf_nat_inet_in_range(const struct nf_conntrack_tuple *t,
>  static bool l4proto_in_range(const struct nf_conntrack_tuple *tuple,
>  			     enum nf_nat_manip_type maniptype,
>  			     const union nf_conntrack_man_proto *min,
> -			     const union nf_conntrack_man_proto *max)
> +			     const union nf_conntrack_man_proto *max,
> +			     const union nf_conntrack_man_proto *base,
> +			     bool is_psid)
>  {
>  	__be16 port;
> +	u16 psid, psid_mask, offset_mask;
> +
> +	/* In this case we are in PSID mode, avoid checking all ranges by computing bitmasks */
> +	if (is_psid) {
> +		u16 power_j = ntohs(max->all) - ntohs(min->all) + 1;
> +		u32 offset = ntohs(base->all);
> +		u16 power_a;
> +
> +		if (offset == 0)
> +			offset = 1 << 16;
> +
> +		power_a = (1 << 16) / offset;

Since the dividie is only needed nat setup and not for each packet I
think its ok.

> +	if (range->flags & NF_NAT_RANGE_PSID) {
> +		u16 base = ntohs(range->base_proto.all);
> +		u16 min =  ntohs(range->min_proto.all);
> +		u16 off = 0;
> +
> +		/* If offset=0, port range is in one contiguous block */
> +		if (base)
> +			off = prandom_u32() % (((1 << 16) / base) - 1);

Bases 32769 > gives 0 for the modulo value, so perhaps compute that
independently.

You could reject > 32769 in the iptables checkentry target.

Also, base of 21846 and above always give 0 result (% 1).

I don't know psid well enough to give a recommendation here.

If such inputs are nonsensical, just reject it when userspace asks for
this and add a 

if (WARN_ON_ONCE(base > bogus))
	return NF_DROP;

with s small coment explaining that xtables is supposed to not provide
such value.

Other than this I think its ok.

I still dislike the 'bool is_psid' in the nat core, but I can't find
a better solution.

  reply	other threads:[~2021-07-16 15:18 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-22  2:35 [PATCH] " Cole Dishington
2021-04-26 12:23 ` Florian Westphal
2021-06-29  0:48   ` Cole Dishington
2021-06-30 14:20     ` Florian Westphal
     [not found]       ` <20210705040856.25191-1-Cole.Dishington@alliedtelesis.co.nz>
2021-07-05  4:08         ` [PATCH] net: netfilter: Add RFC-7597 Section 5.1 PSID support xtables API Cole Dishington
2021-07-05  4:08         ` [PATCH] net: netfilter: Add RFC-7597 Section 5.1 PSID support Cole Dishington
2021-07-05 10:39           ` Florian Westphal
2021-07-16  0:27             ` [PATCH 0/3] " Cole Dishington
2021-07-16  0:27               ` [PATCH 1/3] net: netfilter: Add RFC-7597 Section 5.1 PSID support xtables API Cole Dishington
2021-07-16  0:27               ` [PATCH 2/3] net: netfilter: Add RFC-7597 Section 5.1 PSID support Cole Dishington
2021-07-16 15:18                 ` Florian Westphal [this message]
2021-07-19  1:21                   ` Cole Dishington
2021-07-22  7:17                     ` Florian Westphal
2021-07-25 23:28                       ` Cole Dishington
2021-07-26 14:37                         ` Florian Westphal
2021-08-09  4:10                           ` [PATCH net-next 0/3] " Cole Dishington
2021-08-09  4:10                             ` [PATCH net-next 1/3] net: netfilter: Add RFC-7597 Section 5.1 PSID support xtables API Cole Dishington
2021-08-09  4:10                             ` [PATCH net-next 2/3] net: netfilter: Add RFC-7597 Section 5.1 PSID support Cole Dishington
2021-08-25 17:05                               ` Pablo Neira Ayuso
2021-08-29 21:30                                 ` Cole Dishington
2021-08-09  4:10                             ` [PATCH net-next 3/3] selftests: netfilter: Add RFC-7597 Section 5.1 PSID selftests Cole Dishington
2021-07-16  0:27               ` [PATCH " Cole Dishington
2021-07-05  4:08         ` [PATCH] " Cole Dishington

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210716151833.GD9904@breakpoint.cc \
    --to=fw@strlen.de \
    --cc=Cole.Dishington@alliedtelesis.co.nz \
    --cc=anthony.lineham@alliedtelesis.co.nz \
    --cc=blair.steven@alliedtelesis.co.nz \
    --cc=coreteam@netfilter.org \
    --cc=davem@davemloft.net \
    --cc=kadlec@netfilter.org \
    --cc=kuba@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=netfilter-devel@vger.kernel.org \
    --cc=pablo@netfilter.org \
    --cc=scott.parlane@alliedtelesis.co.nz \
    --cc=shuah@kernel.org \
    --subject='Re: [PATCH 2/3] net: netfilter: Add RFC-7597 Section 5.1 PSID support' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).