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-rw-r--r--src/libcore/loopback-setup.c90
1 files changed, 90 insertions, 0 deletions
diff --git a/src/libcore/loopback-setup.c b/src/libcore/loopback-setup.c
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+++ b/src/libcore/loopback-setup.c
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+/***
+ This file is part of systemd.
+
+ Copyright 2010 Lennart Poettering
+
+ 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 <net/if.h>
+#include <stdlib.h>
+
+#include <systemd/sd-netlink.h>
+
+#include "loopback-setup.h"
+#include "missing.h"
+#include "netlink-util.h"
+
+static int start_loopback(sd_netlink *rtnl) {
+ _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *req = NULL;
+ int r;
+
+ r = sd_rtnl_message_new_link(rtnl, &req, RTM_SETLINK, LOOPBACK_IFINDEX);
+ if (r < 0)
+ return r;
+
+ r = sd_rtnl_message_link_set_flags(req, IFF_UP, IFF_UP);
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_call(rtnl, req, 0, NULL);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+static bool check_loopback(sd_netlink *rtnl) {
+ _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *req = NULL, *reply = NULL;
+ unsigned flags;
+ int r;
+
+ r = sd_rtnl_message_new_link(rtnl, &req, RTM_GETLINK, LOOPBACK_IFINDEX);
+ if (r < 0)
+ return false;
+
+ r = sd_netlink_call(rtnl, req, 0, &reply);
+ if (r < 0)
+ return false;
+
+ r = sd_rtnl_message_link_get_flags(reply, &flags);
+ if (r < 0)
+ return false;
+
+ return flags & IFF_UP;
+}
+
+int loopback_setup(void) {
+ _cleanup_(sd_netlink_unrefp) sd_netlink *rtnl = NULL;
+ int r;
+
+ r = sd_netlink_open(&rtnl);
+ if (r < 0)
+ return r;
+
+ r = start_loopback(rtnl);
+ if (r < 0) {
+
+ /* If we lack the permissions to configure the
+ * loopback device, but we find it to be already
+ * configured, let's exit cleanly, in order to
+ * supported unprivileged containers. */
+ if (r == -EPERM && check_loopback(rtnl))
+ return 0;
+
+ return log_warning_errno(r, "Failed to configure loopback device: %m");
+ }
+
+ return 0;
+}