From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: [PATCH 09/12] netfilter: xt_osf: Add missing permission checks Date: Wed, 13 Dec 2017 19:45:17 +0100 Message-ID: <20171213184520.8193-10-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: In-Reply-To: <20171213184520.8193-1-pablo@netfilter.org> Sender: netdev-owner@vger.kernel.org List-Id: netfilter-devel.vger.kernel.org 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, xt_osf_fingers 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: vpnns -- nfnl_osf -f /tmp/pf.os vpnns -- nfnl_osf -f /tmp/pf.os -d These non-root operations successfully modify the systemwide OS fingerprint list. Add new capable() checks so that they can't. Signed-off-by: Kevin Cernekee Signed-off-by: Pablo Neira Ayuso --- net/netfilter/xt_osf.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/net/netfilter/xt_osf.c b/net/netfilter/xt_osf.c index 36e14b1f061d..a34f314a8c23 100644 --- a/net/netfilter/xt_osf.c +++ b/net/netfilter/xt_osf.c @@ -19,6 +19,7 @@ #include #include +#include #include #include #include @@ -70,6 +71,9 @@ static int xt_osf_add_callback(struct net *net, struct sock *ctnl, struct xt_osf_finger *kf = NULL, *sf; int err = 0; + if (!capable(CAP_NET_ADMIN)) + return -EPERM; + if (!osf_attrs[OSF_ATTR_FINGER]) return -EINVAL; @@ -115,6 +119,9 @@ static int xt_osf_remove_callback(struct net *net, struct sock *ctnl, struct xt_osf_finger *sf; int err = -ENOENT; + if (!capable(CAP_NET_ADMIN)) + return -EPERM; + if (!osf_attrs[OSF_ATTR_FINGER]) return -EINVAL; -- 2.11.0