From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: [PATCH 07/12] netfilter: nfnetlink_cthelper: Add missing permission checks Date: Wed, 13 Dec 2017 19:45:15 +0100 Message-ID: <20171213184520.8193-8-pablo@netfilter.org> References: <20171213184520.8193-1-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]:42558 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753718AbdLMSpg (ORCPT ); Wed, 13 Dec 2017 13:45:36 -0500 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id 7741B174D02 for ; Wed, 13 Dec 2017 19:45:34 +0100 (CET) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 65A0E8E791 for ; Wed, 13 Dec 2017 19:45:34 +0100 (CET) In-Reply-To: <20171213184520.8193-1-pablo@netfilter.org> Sender: netfilter-devel-owner@vger.kernel.org List-ID: From: Kevin Cernekee The capability check in nfnetlink_rcv() verifies that the caller has CAP_NET_ADMIN in the namespace that "owns" the netlink socket. However, nfnl_cthelper_list is shared by all net namespaces on the system. An unprivileged user can create user and net namespaces in which he holds CAP_NET_ADMIN to bypass the netlink_net_capable() check: $ nfct helper list nfct v1.4.4: netlink error: Operation not permitted $ vpnns -- nfct helper list { .name = ftp, .queuenum = 0, .l3protonum = 2, .l4protonum = 6, .priv_data_len = 24, .status = enabled, }; Add capable() checks in nfnetlink_cthelper, as this is cleaner than trying to generalize the solution. Signed-off-by: Kevin Cernekee Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nfnetlink_cthelper.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/net/netfilter/nfnetlink_cthelper.c b/net/netfilter/nfnetlink_cthelper.c index 41628b393673..d33ce6d5ebce 100644 --- a/net/netfilter/nfnetlink_cthelper.c +++ b/net/netfilter/nfnetlink_cthelper.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include @@ -407,6 +408,9 @@ static int nfnl_cthelper_new(struct net *net, struct sock *nfnl, struct nfnl_cthelper *nlcth; int ret = 0; + if (!capable(CAP_NET_ADMIN)) + return -EPERM; + if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE]) return -EINVAL; @@ -611,6 +615,9 @@ static int nfnl_cthelper_get(struct net *net, struct sock *nfnl, struct nfnl_cthelper *nlcth; bool tuple_set = false; + if (!capable(CAP_NET_ADMIN)) + return -EPERM; + if (nlh->nlmsg_flags & NLM_F_DUMP) { struct netlink_dump_control c = { .dump = nfnl_cthelper_dump_table, @@ -678,6 +685,9 @@ static int nfnl_cthelper_del(struct net *net, struct sock *nfnl, struct nfnl_cthelper *nlcth, *n; int j = 0, ret; + if (!capable(CAP_NET_ADMIN)) + return -EPERM; + if (tb[NFCTH_NAME]) helper_name = nla_data(tb[NFCTH_NAME]); -- 2.11.0