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Commit 4a92602a authored by Tycho Andersen's avatar Tycho Andersen Committed by David S. Miller
Browse files

openvswitch: allow management from inside user namespaces 



Operations with the GENL_ADMIN_PERM flag fail permissions checks because
this flag means we call netlink_capable, which uses the init user ns.

Instead, let's introduce a new flag, GENL_UNS_ADMIN_PERM for operations
which should be allowed inside a user namespace.

The motivation for this is to be able to run openvswitch in unprivileged
containers. I've tested this and it seems to work, but I really have no
idea about the security consequences of this patch, so thoughts would be
much appreciated.

v2: use the GENL_UNS_ADMIN_PERM flag instead of a check in each function
v3: use separate ifs for UNS_ADMIN_PERM and ADMIN_PERM, instead of one
    massive one

Reported-by: default avatarJames Page <james.page@canonical.com>
Signed-off-by: default avatarTycho Andersen <tycho.andersen@canonical.com>
CC: Eric Biederman <ebiederm@xmission.com>
CC: Pravin Shelar <pshelar@ovn.org>
CC: Justin Pettit <jpettit@nicira.com>
CC: "David S. Miller" <davem@davemloft.net>
Acked-by: default avatarPravin B Shelar <pshelar@ovn.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4456ed04

include/uapi/linux/genetlink.h

+1 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ struct genlmsghdr { 
#define GENL_CMD_CAP_DO		0x02

#define GENL_CMD_CAP_DUMP	0x04

#define GENL_CMD_CAP_HASPOL	0x08

#define GENL_UNS_ADMIN_PERM	0x10



/*

 * List of reserved static generic netlink identifiers:

net/netlink/genetlink.c

+4 −0
Original line number Diff line number Diff line
@@ -580,6 +580,10 @@ static int genl_family_rcv_msg(struct genl_family *family, 
	    !netlink_capable(skb, CAP_NET_ADMIN))

		return -EPERM;



	if ((ops->flags & GENL_UNS_ADMIN_PERM) &&

	    !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))

		return -EPERM;



	if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {

		int rc;

net/openvswitch/datapath.c

+10 −10
Original line number Diff line number Diff line
@@ -654,7 +654,7 @@ static const struct nla_policy packet_policy[OVS_PACKET_ATTR_MAX + 1] = { 


static const struct genl_ops dp_packet_genl_ops[] = {

	{ .cmd = OVS_PACKET_CMD_EXECUTE,

	  .flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .flags = GENL_UNS_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .policy = packet_policy,

	  .doit = ovs_packet_cmd_execute

	}
@@ -1391,12 +1391,12 @@ static const struct nla_policy flow_policy[OVS_FLOW_ATTR_MAX + 1] = { 


static const struct genl_ops dp_flow_genl_ops[] = {

	{ .cmd = OVS_FLOW_CMD_NEW,

	  .flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .flags = GENL_UNS_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .policy = flow_policy,

	  .doit = ovs_flow_cmd_new

	},

	{ .cmd = OVS_FLOW_CMD_DEL,

	  .flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .flags = GENL_UNS_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .policy = flow_policy,

	  .doit = ovs_flow_cmd_del

	},
@@ -1407,7 +1407,7 @@ static const struct genl_ops dp_flow_genl_ops[] = { 
	  .dumpit = ovs_flow_cmd_dump

	},

	{ .cmd = OVS_FLOW_CMD_SET,

	  .flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .flags = GENL_UNS_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .policy = flow_policy,

	  .doit = ovs_flow_cmd_set,

	},
@@ -1777,12 +1777,12 @@ static const struct nla_policy datapath_policy[OVS_DP_ATTR_MAX + 1] = { 


static const struct genl_ops dp_datapath_genl_ops[] = {

	{ .cmd = OVS_DP_CMD_NEW,

	  .flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .flags = GENL_UNS_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .policy = datapath_policy,

	  .doit = ovs_dp_cmd_new

	},

	{ .cmd = OVS_DP_CMD_DEL,

	  .flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .flags = GENL_UNS_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .policy = datapath_policy,

	  .doit = ovs_dp_cmd_del

	},
@@ -1793,7 +1793,7 @@ static const struct genl_ops dp_datapath_genl_ops[] = { 
	  .dumpit = ovs_dp_cmd_dump

	},

	{ .cmd = OVS_DP_CMD_SET,

	  .flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .flags = GENL_UNS_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .policy = datapath_policy,

	  .doit = ovs_dp_cmd_set,

	},
@@ -2158,12 +2158,12 @@ static const struct nla_policy vport_policy[OVS_VPORT_ATTR_MAX + 1] = { 


static const struct genl_ops dp_vport_genl_ops[] = {

	{ .cmd = OVS_VPORT_CMD_NEW,

	  .flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .flags = GENL_UNS_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .policy = vport_policy,

	  .doit = ovs_vport_cmd_new

	},

	{ .cmd = OVS_VPORT_CMD_DEL,

	  .flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .flags = GENL_UNS_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .policy = vport_policy,

	  .doit = ovs_vport_cmd_del

	},
@@ -2174,7 +2174,7 @@ static const struct genl_ops dp_vport_genl_ops[] = { 
	  .dumpit = ovs_vport_cmd_dump

	},

	{ .cmd = OVS_VPORT_CMD_SET,

	  .flags = GENL_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .flags = GENL_UNS_ADMIN_PERM, /* Requires CAP_NET_ADMIN privilege. */

	  .policy = vport_policy,

	  .doit = ovs_vport_cmd_set,

	},