This is a partial backport of upstream commit 4d54cc32112d ("mptcp:
avoid lock_fast usage in accept path"). It is only a partial backport
because the patch in the link below was erroneously squash-merged into
upstream commit 4d54cc32112d ("mptcp: avoid lock_fast usage in accept
path"). Below is the original patch description from Florian Westphal:
"
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.
"
Link: https://lore.kernel.org/mptcp/20210213000001.379332-8-mathew.j.martineau@linux.intel.com/
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
284c1d76dd