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Date:   Wed, 31 Mar 2021 22:22:30 +0200
From:   Pablo Neira Ayuso <pablo@netfilter.org>
To:     Richard Guy Briggs <rgb@redhat.com>
Cc:     Linux-Audit Mailing List <linux-audit@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>,
        netfilter-devel@vger.kernel.org, Paul Moore <paul@paul-moore.com>,
        Eric Paris <eparis@parisplace.org>,
        Steve Grubb <sgrubb@redhat.com>,
        Florian Westphal <fw@strlen.de>, Phil Sutter <phil@nwl.cc>,
        twoerner@redhat.com, tgraf@infradead.org, dan.carpenter@oracle.com,
        Jones Desougi <jones.desougi+netfilter@gmail.com>
Subject: Re: [PATCH v5] audit: log nftables configuration change events once
 per table
Message-ID: <20210331202230.GA4109@salvia>
References: <28de34275f58b45fd4626a92ccae96b6d2b4e287.1616702731.git.rgb@redhat.com>
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On Fri, Mar 26, 2021 at 01:38:59PM -0400, Richard Guy Briggs wrote:
> Reduce logging of nftables events to a level similar to iptables.
> Restore the table field to list the table, adding the generation.
> 
> Indicate the op as the most significant operation in the event.

There's a UAF, Florian reported. I'm attaching an incremental fix.

nf_tables_commit_audit_collect() refers to the trans object which
might have been already released.

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Content-Disposition: attachment; filename="fix-uaf.patch"

commit e4d272948d25b66d86fc241cefd95281bfb1079e
Author: Pablo Neira Ayuso <pablo@netfilter.org>
Date:   Wed Mar 31 22:19:51 2021 +0200

    netfilter: nf_tables: use-after-free
    
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 5dd4bb7cabf5..01674c0d9103 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -8063,6 +8063,8 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
 	net->nft.gencursor = nft_gencursor_next(net);
 
 	list_for_each_entry_safe(trans, next, &net->nft.commit_list, list) {
+		nf_tables_commit_audit_collect(&adl, trans->ctx.table,
+					       trans->msg_type);
 		switch (trans->msg_type) {
 		case NFT_MSG_NEWTABLE:
 			if (nft_trans_table_update(trans)) {
@@ -8211,8 +8213,6 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
 			}
 			break;
 		}
-		nf_tables_commit_audit_collect(&adl, trans->ctx.table,
-					       trans->msg_type);
 	}
 
 	nft_commit_notify(net, NETLINK_CB(skb).portid);

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