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>

diff --git a/include/uapi/linux/genetlink.h b/include/uapi/linux/genetlink.h
index c3363ba1ae057f66dc5b878ee9fde7899857c450..5512c90af7e30f5593fbba398882f99a62fe65c0 100644 (file)
--- a/include/uapi/linux/genetlink.h
+++ b/include/uapi/linux/genetlink.h
@@ -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:

diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index f830326b3b1dbaf63e727e7a4f4f496d5108db64..0ffd721126e7fbb7d1b443e1346f305c08ae3a58 100644 (file)
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -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;
 

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index deadfdab1bc384c858642e176d690bcf62a103c0..d6f7fe92744a4baebed536f72aee9d4c3a66f30c 100644 (file)
--- 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,
        },