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openvswitch: allow management from inside user namespaces

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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>
This commit is contained in:
Tycho Andersen 2016-02-05 09:20:52 -07:00 committed by David S. Miller
parent 4456ed04ea
commit 4a92602aa1
3 changed files with 15 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/uapi/linux/genetlink.h
View File

@ -21,6 +21,7 @@ struct genlmsghdr {
#define GENL_CMD_CAP_DO 0x02 #define GENL_CMD_CAP_DO 0x02
#define GENL_CMD_CAP_DUMP 0x04 #define GENL_CMD_CAP_DUMP 0x04
#define GENL_CMD_CAP_HASPOL 0x08 #define GENL_CMD_CAP_HASPOL 0x08
#define GENL_UNS_ADMIN_PERM 0x10
/* /*
* List of reserved static generic netlink identifiers: * List of reserved static generic netlink identifiers:

4
net/netlink/genetlink.c
View File

@ -580,6 +580,10 @@ static int genl_family_rcv_msg(struct genl_family *family,
!netlink_capable(skb, CAP_NET_ADMIN)) !netlink_capable(skb, CAP_NET_ADMIN))
return -EPERM; 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) { if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP) {
int rc; int rc;

20
net/openvswitch/datapath.c
View File

@ -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[] = { static const struct genl_ops dp_packet_genl_ops[] = {
{ .cmd = OVS_PACKET_CMD_EXECUTE, { .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, .policy = packet_policy,
.doit = ovs_packet_cmd_execute .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[] = { static const struct genl_ops dp_flow_genl_ops[] = {
{ .cmd = OVS_FLOW_CMD_NEW, { .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, .policy = flow_policy,
.doit = ovs_flow_cmd_new .doit = ovs_flow_cmd_new
}, },
{ .cmd = OVS_FLOW_CMD_DEL, { .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, .policy = flow_policy,
.doit = ovs_flow_cmd_del .doit = ovs_flow_cmd_del
}, },
@ -1407,7 +1407,7 @@ static const struct genl_ops dp_flow_genl_ops[] = {
.dumpit = ovs_flow_cmd_dump .dumpit = ovs_flow_cmd_dump
}, },
{ .cmd = OVS_FLOW_CMD_SET, { .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, .policy = flow_policy,
.doit = ovs_flow_cmd_set, .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[] = { static const struct genl_ops dp_datapath_genl_ops[] = {
{ .cmd = OVS_DP_CMD_NEW, { .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, .policy = datapath_policy,
.doit = ovs_dp_cmd_new .doit = ovs_dp_cmd_new
}, },
{ .cmd = OVS_DP_CMD_DEL, { .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, .policy = datapath_policy,
.doit = ovs_dp_cmd_del .doit = ovs_dp_cmd_del
}, },
@ -1793,7 +1793,7 @@ static const struct genl_ops dp_datapath_genl_ops[] = {
.dumpit = ovs_dp_cmd_dump .dumpit = ovs_dp_cmd_dump
}, },
{ .cmd = OVS_DP_CMD_SET, { .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, .policy = datapath_policy,
.doit = ovs_dp_cmd_set, .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[] = { static const struct genl_ops dp_vport_genl_ops[] = {
{ .cmd = OVS_VPORT_CMD_NEW, { .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, .policy = vport_policy,
.doit = ovs_vport_cmd_new .doit = ovs_vport_cmd_new
}, },
{ .cmd = OVS_VPORT_CMD_DEL, { .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, .policy = vport_policy,
.doit = ovs_vport_cmd_del .doit = ovs_vport_cmd_del
}, },
@ -2174,7 +2174,7 @@ static const struct genl_ops dp_vport_genl_ops[] = {
.dumpit = ovs_vport_cmd_dump .dumpit = ovs_vport_cmd_dump
}, },
{ .cmd = OVS_VPORT_CMD_SET, { .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, .policy = vport_policy,
.doit = ovs_vport_cmd_set, .doit = ovs_vport_cmd_set,
}, },