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]

1 files changed, 157 insertions, 0 deletions

diff --git a/src/network/networkd-tuntap.c b/src/network/networkd-tuntap.c
new file mode 100644
index 0000000000..19dc2ad252
--- /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);
+}