From a5fad9610f4a757d3822a3383a91fe63b950fc0b Mon Sep 17 00:00:00 2001 From: Kevin Cernekee Date: Tue, 5 Dec 2017 15:42:41 -0800 Subject: [PATCH] netfilter: xt_osf: Add missing permission checks 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 (cherry picked from commit 916a27901de01446bcf57ecca4783f6cff493309) Orabug: 29037831 CVE: CVE-2017-17450 Signed-off-by: John Donnelly Reviewed-by: Darren Kenny Signed-off-by: Brian Maly --- 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 0778855ea5e75..20f7bd64ad403 100644 --- a/net/netfilter/xt_osf.c +++ b/net/netfilter/xt_osf.c @@ -19,6 +19,7 @@ #include #include +#include #include #include #include @@ -69,6 +70,9 @@ static int xt_osf_add_callback(struct sock *ctnl, struct sk_buff *skb, 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; @@ -112,6 +116,9 @@ static int xt_osf_remove_callback(struct sock *ctnl, struct sk_buff *skb, struct xt_osf_finger *sf; int err = -ENOENT; + if (!capable(CAP_NET_ADMIN)) + return -EPERM; + if (!osf_attrs[OSF_ATTR_FINGER]) return -EINVAL; -- 2.50.1