netfilter: xt_osf: Add missing permission checks
CVE-2017-17450
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 <cernekee@chromium.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
(cherry picked from commit
916a27901de01446bcf57ecca4783f6cff493309)
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Acked-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>