From c862d7df67f26d86bb0de2ea863231d48d1396e9 Mon Sep 17 00:00:00 2001 From: Julian Orth Date: Tue, 11 Sep 2018 19:17:48 +0200 Subject: netlink: restrict access to the UDP socket To interact with the UDP socket the caller must either be in the network namespace of the socket or have CAP_NET_ADMIN in that network namespace. --- src/netlink.c | 21 ++++++++++++++++++--- src/uapi/wireguard.h | 7 +++++++ 2 files changed, 25 insertions(+), 3 deletions(-) diff --git a/src/netlink.c b/src/netlink.c index 96ad555..e17c3e1 100644 --- a/src/netlink.c +++ b/src/netlink.c @@ -173,6 +173,14 @@ static struct net *get_attr_net(struct nlattr *net_pid, struct nlattr *net_fd) return NULL; } +static int test_socket_net_capable(struct net *net) +{ + if (net != current->nsproxy->net_ns && + !ns_capable(net->user_ns, CAP_NET_ADMIN)) + return -EPERM; + return 0; +} + static int wg_get_device_start(struct netlink_callback *cb) { struct nlattr **attrs = genl_family_attrbuf(&genl_family); @@ -249,9 +257,12 @@ static int wg_get_device_dump(struct sk_buff *skb, struct netlink_callback *cb) genl_dump_check_consistent(cb, hdr); if (!last_peer_cursor) { - if (nla_put_u16(skb, WGDEVICE_A_LISTEN_PORT, - wg->incoming_port) || - nla_put_u32(skb, WGDEVICE_A_FWMARK, wg->fwmark) || + if (test_socket_net_capable(wg->creating_net) == 0) { + if (nla_put_u16(skb, WGDEVICE_A_LISTEN_PORT, + wg->incoming_port)) + goto out; + } + if (nla_put_u32(skb, WGDEVICE_A_FWMARK, wg->fwmark) || nla_put_u32(skb, WGDEVICE_A_IFINDEX, wg->dev->ifindex) || nla_put_string(skb, WGDEVICE_A_IFNAME, wg->dev->name)) goto out; @@ -338,7 +349,11 @@ static int wg_get_device_done(struct netlink_callback *cb) static int set_port(struct wg_device *wg, u16 port) { struct wg_peer *peer; + int ret; + ret = test_socket_net_capable(wg->creating_net); + if (ret) + return ret; if (wg->incoming_port == port) return 0; list_for_each_entry(peer, &wg->peer_list, peer_list) diff --git a/src/uapi/wireguard.h b/src/uapi/wireguard.h index bcfcf4f..8b60ad1 100644 --- a/src/uapi/wireguard.h +++ b/src/uapi/wireguard.h @@ -30,6 +30,9 @@ * socket. The caller must have CAP_NET_ADMIN in the namespace of the Wireguard * device. * + * If the caller is not in the transit namespace and does not have CAP_NET_ADMIN + * in the transit namespace, then the WGDEVICE_A_LISTEN_PORT is not returned. + * * The kernel will then return several messages (NLM_F_MULTI) containing the * following tree of nested items: * @@ -92,6 +95,10 @@ * of the netlink socket. The caller must have CAP_NET_ADMIN in the namespace of * the Wireguard device. * + * If WGDEVICE_A_LISTEN_PORT is provided and the calling process is not in the + * transit namespace, then the calling process must have CAP_NET_ADMIN the + * transit namespace. + * * WGDEVICE_A_IFINDEX: NLA_U32 * WGDEVICE_A_IFNAME: NLA_NUL_STRING, maxlen IFNAMESIZ - 1 * WGDEVICE_A_FLAGS: NLA_U32, 0 or WGDEVICE_F_REPLACE_PEERS if all current -- cgit v1.2.3-59-g8ed1b