diff options
| author | Nikolaos Gkarlis <nickgarlis@gmail.com> | 2026-04-02 20:14:32 +0200 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-04-03 15:07:18 -0700 |
| commit | 7b735ef81286007794a227ce2539419479c02a5f (patch) | |
| tree | 9a89ef42171def20bc2a22d5beb6f8bfcac0d59e | |
| parent | 1979645e1842cb7017525a61a0e0e0beb924d02a (diff) | |
rtnetlink: add missing netlink_ns_capable() check for peer netns
rtnl_newlink() lacks a CAP_NET_ADMIN capability check on the peer
network namespace when creating paired devices (veth, vxcan,
netkit). This allows an unprivileged user with a user namespace
to create interfaces in arbitrary network namespaces, including
init_net.
Add a netlink_ns_capable() check for CAP_NET_ADMIN in the peer
namespace before allowing device creation to proceed.
Fixes: 81adee47dfb6 ("net: Support specifying the network namespace upon device creation.")
Signed-off-by: Nikolaos Gkarlis <nickgarlis@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260402181432.4126920-1-nickgarlis@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | net/core/rtnetlink.c | 40 |
1 files changed, 27 insertions, 13 deletions
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index fae8034efbff..69daba3ddaf0 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -3894,28 +3894,42 @@ out_unregister: goto out; } -static struct net *rtnl_get_peer_net(const struct rtnl_link_ops *ops, +static struct net *rtnl_get_peer_net(struct sk_buff *skb, + const struct rtnl_link_ops *ops, struct nlattr *tbp[], struct nlattr *data[], struct netlink_ext_ack *extack) { - struct nlattr *tb[IFLA_MAX + 1]; + struct nlattr *tb[IFLA_MAX + 1], **attrs; + struct net *net; int err; - if (!data || !data[ops->peer_type]) - return rtnl_link_get_net_ifla(tbp); - - err = rtnl_nla_parse_ifinfomsg(tb, data[ops->peer_type], extack); - if (err < 0) - return ERR_PTR(err); - - if (ops->validate) { - err = ops->validate(tb, NULL, extack); + if (!data || !data[ops->peer_type]) { + attrs = tbp; + } else { + err = rtnl_nla_parse_ifinfomsg(tb, data[ops->peer_type], extack); if (err < 0) return ERR_PTR(err); + + if (ops->validate) { + err = ops->validate(tb, NULL, extack); + if (err < 0) + return ERR_PTR(err); + } + + attrs = tb; } - return rtnl_link_get_net_ifla(tb); + net = rtnl_link_get_net_ifla(attrs); + if (IS_ERR_OR_NULL(net)) + return net; + + if (!netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN)) { + put_net(net); + return ERR_PTR(-EPERM); + } + + return net; } static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, @@ -4054,7 +4068,7 @@ static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, } if (ops->peer_type) { - peer_net = rtnl_get_peer_net(ops, tb, data, extack); + peer_net = rtnl_get_peer_net(skb, ops, tb, data, extack); if (IS_ERR(peer_net)) { ret = PTR_ERR(peer_net); goto put_ops; |