networkd: Introduce tun/tap device

This patch introduces TUN/TAP device creation support
to networkd.

Example conf to create a tap device:

file: tap.netdev
------------------
[NetDev]
Name=tap-test
Kind=tap

[Tap]
OneQueue=true
MultiQueue=true
PacketInfo=true
User=sus
Group=sus
------------------

Test:
1. output of ip link
tap-test: tap pi one_queue UNKNOWN_FLAGS:900 user 1000 group 1000

id:
uid=1000(sus) gid=10(wheel) groups=10(wheel),1000(sus)
context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023

Modifications:

Added:
1. file networkd-tuntap.c
3. netdev kind NETDEV_KIND_TUN and NETDEV_KIND_TAP
2. Tun and Tap Sections and config params to parse
   conf and gperf conf parameters

[tomegun: tweak the 'kind' checking for received ifindex]

4 files changed, 201 insertions, 7 deletions

diff --git a/src/network/networkd-netdev-gperf.gperf b/src/network/networkd-netdev-gperf.gperf
index 9125e1db4..5955f5195 100644
--- a/src/network/networkd-netdev-gperf.gperf
+++ b/src/network/networkd-netdev-gperf.gperf
@@ -38,3 +38,13 @@ VXLAN.Group,             config_parse_tunnel_address,        0,
 VXLAN.TOS,               config_parse_unsigned,              0,                             offsetof(NetDev, tos)
 VXLAN.TTL,               config_parse_unsigned,              0,                             offsetof(NetDev, ttl)
 VXLAN.MacLearning,       config_parse_bool,                  0,                             offsetof(NetDev, learning)
+Tun.OneQueue,            config_parse_bool,                  0,                             offsetof(NetDev, one_queue)
+Tun.MultiQueue,          config_parse_bool,                  0,                             offsetof(NetDev, multi_queue)
+Tun.PacketInfo,          config_parse_bool,                  0,                             offsetof(NetDev, packet_info)
+Tun.User,                config_parse_string,                0,                             offsetof(NetDev, user_name)
+Tun.Group,               config_parse_string,                0,                             offsetof(NetDev, group_name)
+Tap.OneQueue,            config_parse_bool,                  0,                             offsetof(NetDev, one_queue)
+Tap.MultiQueue,          config_parse_bool,                  0,                             offsetof(NetDev, multi_queue)
+Tap.PacketInfo,          config_parse_bool,                  0,                             offsetof(NetDev, packet_info)
+Tap.User,                config_parse_string,                0,                             offsetof(NetDev, user_name)
+Tap.Group,               config_parse_string,                0,                             offsetof(NetDev, group_name)
diff --git a/src/network/networkd-netdev.c b/src/network/networkd-netdev.c
index eaa8bede7..cc85e5348 100644
--- a/src/network/networkd-netdev.c
+++ b/src/network/networkd-netdev.c
@@ -41,6 +41,8 @@ static const char* const netdev_kind_table[_NETDEV_KIND_MAX] = {
         [NETDEV_KIND_VETH] = "veth",
         [NETDEV_KIND_VTI] = "vti",
         [NETDEV_KIND_DUMMY] = "dummy",
+        [NETDEV_KIND_TUN] = "tun",
+        [NETDEV_KIND_TAP] = "tap",
 };
 
 DEFINE_STRING_TABLE_LOOKUP(netdev_kind, NetDevKind);
@@ -86,6 +88,8 @@ static void netdev_free(NetDev *netdev) {
         free(netdev->ifname_peer);
         free(netdev->mac);
         free(netdev->mac_peer);
+        free(netdev->user_name);
+        free(netdev->group_name);
 
         condition_free_list(netdev->match_host);
         condition_free_list(netdev->match_virt);
@@ -484,15 +488,21 @@ int netdev_set_ifindex(NetDev *netdev, sd_rtnl_message *message) {
                 return r;
         }
 
-        kind = netdev_kind_to_string(netdev->kind);
-        if (!kind) {
-                log_error_netdev(netdev, "Could not get kind");
-                netdev_enter_failed(netdev);
-                return -EINVAL;
+        if (netdev->kind == NETDEV_KIND_TAP)
+                /* the kernel does not distinguish between tun and tap */
+                kind = "tun";
+        else {
+                kind = netdev_kind_to_string(netdev->kind);
+                if (!kind) {
+                        log_error_netdev(netdev, "Could not get kind");
+                        netdev_enter_failed(netdev);
+                        return -EINVAL;
+                }
         }
 
         if (!streq(kind, received_kind)) {
-                log_error_netdev(netdev, "Received newlink with wrong KIND %s, "
+                log_error_netdev(netdev,
+                                 "Received newlink with wrong KIND %s, "
                                  "expected %s", received_kind, kind);
                 netdev_enter_failed(netdev);
                 return r;
@@ -589,7 +599,7 @@ static int netdev_load_one(Manager *manager, const char *filename) {
         netdev->learning = true;
 
         r = config_parse(NULL, filename, file,
-                         "Match\0NetDev\0VLAN\0MACVLAN\0VXLAN\0Tunnel\0Peer\0",
+                         "Match\0NetDev\0VLAN\0MACVLAN\0VXLAN\0Tunnel\0Peer\0Tun\0Tap\0",
                          config_item_perf_lookup, (void*) network_netdev_gperf_lookup,
                          false, false, netdev);
         if (r < 0) {
@@ -695,6 +705,14 @@ static int netdev_load_one(Manager *manager, const char *filename) {
                 if (r < 0)
                         return r;
                 break;
+
+        case NETDEV_KIND_TUN:
+        case NETDEV_KIND_TAP:
+                r = netdev_create_tuntap(netdev);
+                if (r < 0)
+                        return r;
+                break;
+
         default:
                 break;
         }
diff --git a/src/network/networkd-tuntap.c b/src/network/networkd-tuntap.c
new file mode 100644
index 000000000..19dc2ad25
--- /dev/null
+++ b/src/network/networkd-tuntap.c
@@ -0,0 +1,157 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+    This file is part of systemd.
+
+    Copyright 2014 Susant Sahani <susant@redhat.com>
+
+    systemd is free software; you can redistribute it and/or modify it
+    under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 2.1 of the License, or
+    (at your option) any later version.
+
+    systemd is distributed in the hope that it will be useful, but
+    WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <sys/ioctl.h>
+#include <net/if.h>
+#include <linux/if_tun.h>
+
+#include "networkd.h"
+
+#define TUN_DEV "/dev/net/tun"
+
+
+static int netdev_fill_tuntap_message(NetDev *netdev, struct ifreq *ifr) {
+
+        assert(netdev);
+        assert(ifr);
+
+        memset(ifr, 0, sizeof(*ifr));
+
+        if (netdev->kind != NETDEV_KIND_TAP)
+                ifr->ifr_flags |= IFF_TUN;
+        else
+                ifr->ifr_flags |= IFF_TAP;
+
+        if (netdev->packet_info)
+                ifr->ifr_flags &= ~IFF_NO_PI;
+        else
+                ifr->ifr_flags |= IFF_NO_PI;
+
+        if (netdev->one_queue)
+                ifr->ifr_flags |= IFF_ONE_QUEUE;
+
+        if (netdev->multi_queue)
+                ifr->ifr_flags |= IFF_MULTI_QUEUE;
+
+        strncpy(ifr->ifr_name, netdev->ifname, IFNAMSIZ-1);
+
+        return 0;
+}
+
+static int netdev_tuntap_add(NetDev *netdev, struct ifreq *ifr) {
+        _cleanup_close_ int fd;
+        const char *user;
+        const char *group;
+        uid_t uid;
+        gid_t gid;
+        int r = 0;
+
+        fd = open(TUN_DEV, O_RDWR);
+        if (fd < 0) {
+                log_error_netdev(netdev,
+                                 "Failed to open tun dev: %s",
+                                 strerror(-r));
+                return r;
+        }
+
+        r = ioctl(fd, TUNSETIFF, ifr);
+        if (r < 0) {
+                log_error_netdev(netdev,
+                                 "TUNSETIFF failed on tun dev: %s",
+                                 strerror(-r));
+                return r;
+        }
+
+        if(netdev->user_name) {
+
+                user = netdev->user_name;
+
+                r = get_user_creds(&user, &uid, NULL, NULL, NULL);
+                if (r < 0) {
+                        log_error("Cannot resolve user name %s: %s",
+                                  netdev->user_name, strerror(-r));
+                        return 0;
+                }
+
+                r = ioctl(fd, TUNSETOWNER, uid);
+                if ( r < 0) {
+                        log_error_netdev(netdev,
+                                         "TUNSETOWNER failed on tun dev: %s",
+                                         strerror(-r));
+                }
+        }
+
+        if(netdev->group_name) {
+
+                group = netdev->group_name;
+
+                r = get_group_creds(&group, &gid);
+                if (r < 0) {
+                        log_error("Cannot resolve group name %s: %s",
+                                  netdev->group_name, strerror(-r));
+                        return 0;
+                }
+
+                r = ioctl(fd, TUNSETGROUP, gid);
+                if( r < 0) {
+                        log_error_netdev(netdev,
+                                         "TUNSETGROUP failed on tun dev: %s",
+                                         strerror(-r));
+                        return r;
+                }
+
+        }
+
+        r = ioctl(fd, TUNSETPERSIST, 1);
+        if (r < 0) {
+                log_error_netdev(netdev,
+                                 "TUNSETPERSIST failed on tun dev: %s",
+                                 strerror(-r));
+                return r;
+        }
+
+        return r;
+}
+
+int netdev_create_tuntap(NetDev *netdev) {
+        struct ifreq ifr;
+        int r;
+
+        assert(netdev);
+        assert(netdev->ifname);
+
+        switch(netdev->kind) {
+        case NETDEV_KIND_TUN:
+        case NETDEV_KIND_TAP:
+                break;
+        default:
+                return -ENOTSUP;
+        }
+
+        r = netdev_fill_tuntap_message(netdev, &ifr);
+        if(r < 0)
+                return r;
+
+        log_debug_netdev(netdev, "Creating tuntap netdev: %s",
+                         netdev_kind_to_string(netdev->kind));
+
+        return netdev_tuntap_add(netdev, &ifr);
+}
diff --git a/src/network/networkd.h b/src/network/networkd.h
index 0ba9ee588..67ca41b8a 100644
--- a/src/network/networkd.h
+++ b/src/network/networkd.h
@@ -82,6 +82,8 @@ typedef enum NetDevKind {
         NETDEV_KIND_VETH,
         NETDEV_KIND_VTI,
         NETDEV_KIND_DUMMY,
+        NETDEV_KIND_TUN,
+        NETDEV_KIND_TAP,
         _NETDEV_KIND_MAX,
         _NETDEV_KIND_INVALID = -1
 } NetDevKind;
@@ -110,6 +112,8 @@ struct NetDev {
         char *description;
         char *ifname;
         char *ifname_peer;
+        char *user_name;
+        char *group_name;
         size_t mtu;
         struct ether_addr *mac;
         struct ether_addr *mac_peer;
@@ -124,6 +128,10 @@ struct NetDev {
 
         bool tunnel_pmtudisc;
         bool learning;
+        bool one_queue;
+        bool multi_queue;
+        bool packet_info;
+
         unsigned ttl;
         unsigned tos;
         struct in_addr local;
@@ -359,6 +367,7 @@ int netdev_create_vxlan(NetDev *netdev, Link *link, sd_rtnl_message_handler_t ca
 int netdev_create_vlan(NetDev *netdev, Link *link, sd_rtnl_message_handler_t callback);
 int netdev_create_macvlan(NetDev *netdev, Link *link, sd_rtnl_message_handler_t callback);
 int netdev_create_dummy(NetDev *netdev, sd_rtnl_message_handler_t callback);
+int netdev_create_tuntap(NetDev *netdev);
 
 const char *netdev_kind_to_string(NetDevKind d) _const_;
 NetDevKind netdev_kind_from_string(const char *d) _pure_;