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: James Page <james.page@canonical.com>
Signed-off-by: Tycho 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: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 10 deletions

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index deadfdab1bc3..d6f7fe92744a 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -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,
         },