@@ -14,6 +14,7 @@
*/
struct genl_multicast_group {
char name[GENL_NAMSIZ];
+ u8 flags;
};
struct genl_ops;
@@ -1360,11 +1360,43 @@ static struct genl_family genl_ctrl __ro_after_init = {
.netnsok = true,
};
+static int genl_bind(struct net *net, int group)
+{
+ const struct genl_family *family;
+ unsigned int id;
+ int ret = 0;
+
+ genl_lock_all();
+
+ idr_for_each_entry(&genl_fam_idr, family, id) {
+ const struct genl_multicast_group *grp;
+ int i;
+
+ if (family->n_mcgrps == 0)
+ continue;
+
+ i = group - family->mcgrp_offset;
+ if (i < 0 || i >= family->n_mcgrps)
+ continue;
+
+ grp = &family->mcgrps[i];
+ if ((grp->flags & GENL_UNS_ADMIN_PERM) &&
+ !ns_capable(net->user_ns, CAP_NET_ADMIN))
+ ret = -EPERM;
+
+ break;
+ }
+
+ genl_unlock_all();
+ return ret;
+}
+
static int __net_init genl_pernet_init(struct net *net)
{
struct netlink_kernel_cfg cfg = {
.input = genl_rcv,
.flags = NL_CFG_F_NONROOT_RECV,
+ .bind = genl_bind,
};
/* we'll bump the group number right afterwards */
genetlink sets NL_CFG_F_NONROOT_RECV for its netlink socket so anyone can subscribe to multicast messages. rtnetlink doesn't allow this unconditionally, rtnetlink_bind() restricts bind requests to CAP_NET_ADMIN for a few groups. This allows to set GENL_UNS_ADMIN_PERM flag on genl mcast groups to mandate CAP_NET_ADMIN. This will be used by the upcoming mptcp netlink event facility which exposes the token (mptcp connection identifier) to userspace. Signed-off-by: Florian Westphal <fw@strlen.de> --- include/net/genetlink.h | 1 + net/netlink/genetlink.c | 32 ++++++++++++++++++++++++++++++++ 2 files changed, 33 insertions(+)