From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: [PATCH 04/12] netfilter: xt_connmark: Add bit mapping for bit-shift operation. Date: Mon, 23 Apr 2018 19:57:06 +0200 Message-ID: <20180423175714.9794-5-pablo@netfilter.org> References: <20180423175714.9794-1-pablo@netfilter.org> Cc: davem@davemloft.net, netdev@vger.kernel.org To: netfilter-devel@vger.kernel.org Return-path: Received: from mail.us.es ([193.147.175.20]:36214 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932320AbeDWR5Z (ORCPT ); Mon, 23 Apr 2018 13:57:25 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id 0358020A538 for ; Mon, 23 Apr 2018 19:56:54 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 1D5A2DA4FB for ; Mon, 23 Apr 2018 19:56:46 +0200 (CEST) In-Reply-To: <20180423175714.9794-1-pablo@netfilter.org> Sender: netdev-owner@vger.kernel.org List-ID: From: Jack Ma With the addition of bit-shift operations, we are able to shift ct/skbmark based on user requirements. However, this change might also cause the most left/right hand- side mark to be accidentially lost during shift operations. This patch adds the ability to 'grep' certain bits based on ctmask or nfmask out of the original mark. Then, apply shift operations to achieve a new mapping between ctmark and skb->mark. For example: If someone would like save the fourth F bits of ctmark 0xFFF(F)000F into the seventh hexadecimal (0) skb->mark 0xABC000(0)E. new_targetmark = (ctmark & ctmask) >> 12; (new) skb->mark = (skb->mark &~nfmask) ^ new_targetmark; This will preserve the other bits that are not related to this operation. Fixes: 472a73e00757 ("netfilter: xt_conntrack: Support bit-shifting for CONNMARK & MARK targets.") Reviewed-by: Florian Westphal Signed-off-by: Jack Ma Signed-off-by: Pablo Neira Ayuso --- net/netfilter/xt_connmark.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/net/netfilter/xt_connmark.c b/net/netfilter/xt_connmark.c index 773da82190dc..4b424e6caf3e 100644 --- a/net/netfilter/xt_connmark.c +++ b/net/netfilter/xt_connmark.c @@ -41,6 +41,7 @@ connmark_tg_shift(struct sk_buff *skb, u8 shift_bits, u8 shift_dir) { enum ip_conntrack_info ctinfo; + u_int32_t new_targetmark; struct nf_conn *ct; u_int32_t newmark; @@ -61,24 +62,26 @@ connmark_tg_shift(struct sk_buff *skb, } break; case XT_CONNMARK_SAVE: - newmark = (ct->mark & ~info->ctmask) ^ - (skb->mark & info->nfmask); + new_targetmark = (skb->mark & info->nfmask); if (shift_dir == D_SHIFT_RIGHT) - newmark >>= shift_bits; + new_targetmark >>= shift_bits; else - newmark <<= shift_bits; + new_targetmark <<= shift_bits; + newmark = (ct->mark & ~info->ctmask) ^ + new_targetmark; if (ct->mark != newmark) { ct->mark = newmark; nf_conntrack_event_cache(IPCT_MARK, ct); } break; case XT_CONNMARK_RESTORE: - newmark = (skb->mark & ~info->nfmask) ^ - (ct->mark & info->ctmask); + new_targetmark = (ct->mark & info->ctmask); if (shift_dir == D_SHIFT_RIGHT) - newmark >>= shift_bits; + new_targetmark >>= shift_bits; else - newmark <<= shift_bits; + new_targetmark <<= shift_bits; + newmark = (skb->mark & ~info->nfmask) ^ + new_targetmark; skb->mark = newmark; break; } -- 2.11.0