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-rw-r--r--src/resolve/resolved.c99
-rw-r--r--src/resolve/resolved.conf.in34
2 files changed, 133 insertions, 0 deletions
diff --git a/src/resolve/resolved.c b/src/resolve/resolved.c
new file mode 100644
index 0000000..d3bc902
--- /dev/null
+++ b/src/resolve/resolved.c
@@ -0,0 +1,99 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "sd-daemon.h"
+#include "sd-event.h"
+
+#include "bus-log-control-api.h"
+#include "capability-util.h"
+#include "daemon-util.h"
+#include "main-func.h"
+#include "mkdir-label.h"
+#include "resolved-bus.h"
+#include "resolved-conf.h"
+#include "resolved-manager.h"
+#include "resolved-resolv-conf.h"
+#include "selinux-util.h"
+#include "service-util.h"
+#include "signal-util.h"
+#include "user-util.h"
+
+static int run(int argc, char *argv[]) {
+ _cleanup_(manager_freep) Manager *m = NULL;
+ _unused_ _cleanup_(notify_on_cleanup) const char *notify_stop = NULL;
+ int r;
+
+ log_setup();
+
+ r = service_parse_argv("systemd-resolved.service",
+ "Provide name resolution with caching using DNS, mDNS, LLMNR.",
+ BUS_IMPLEMENTATIONS(&manager_object,
+ &log_control_object),
+ argc, argv);
+ if (r <= 0)
+ return r;
+
+ umask(0022);
+
+ r = mac_selinux_init();
+ if (r < 0)
+ return r;
+
+ /* Drop privileges, but only if we have been started as root. If we are not running as root we assume most
+ * privileges are already dropped and we can't create our directory. */
+ if (getuid() == 0) {
+ const char *user = "systemd-resolve";
+ uid_t uid;
+ gid_t gid;
+
+ r = get_user_creds(&user, &uid, &gid, NULL, NULL, 0);
+ if (r < 0)
+ return log_error_errno(r, "Cannot resolve user name %s: %m", user);
+
+ /* As we're root, we can create the directory where resolv.conf will live */
+ r = mkdir_safe_label("/run/systemd/resolve", 0755, uid, gid, MKDIR_WARN_MODE);
+ if (r < 0)
+ return log_error_errno(r, "Could not create runtime directory: %m");
+
+ /* Drop privileges, but keep three caps. Note that we drop two of those too, later on (see below) */
+ r = drop_privileges(uid, gid,
+ (UINT64_C(1) << CAP_NET_RAW)| /* needed for SO_BINDTODEVICE */
+ (UINT64_C(1) << CAP_NET_BIND_SERVICE)| /* needed to bind on port 53 */
+ (UINT64_C(1) << CAP_SETPCAP) /* needed in order to drop the caps later */);
+ if (r < 0)
+ return log_error_errno(r, "Failed to drop privileges: %m");
+ }
+
+ assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, SIGUSR1, SIGUSR2, SIGRTMIN+1, -1) >= 0);
+
+ r = manager_new(&m);
+ if (r < 0)
+ return log_error_errno(r, "Could not create manager: %m");
+
+ r = manager_start(m);
+ if (r < 0)
+ return log_error_errno(r, "Failed to start manager: %m");
+
+ /* Write finish default resolv.conf to avoid a dangling symlink */
+ (void) manager_write_resolv_conf(m);
+
+ (void) manager_check_resolv_conf(m);
+
+ /* Let's drop the remaining caps now */
+ r = capability_bounding_set_drop((UINT64_C(1) << CAP_NET_RAW), true);
+ if (r < 0)
+ return log_error_errno(r, "Failed to drop remaining caps: %m");
+
+ notify_stop = notify_start(NOTIFY_READY, NOTIFY_STOPPING);
+
+ r = sd_event_loop(m->event);
+ if (r < 0)
+ return log_error_errno(r, "Event loop failed: %m");
+
+ return 0;
+}
+
+DEFINE_MAIN_FUNCTION(run);
diff --git a/src/resolve/resolved.conf.in b/src/resolve/resolved.conf.in
new file mode 100644
index 0000000..6d4176d
--- /dev/null
+++ b/src/resolve/resolved.conf.in
@@ -0,0 +1,34 @@
+# This file is part of systemd.
+#
+# 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.
+#
+# Entries in this file show the compile time defaults. Local configuration
+# should be created by either modifying this file, or by creating "drop-ins" in
+# the resolved.conf.d/ subdirectory. The latter is generally recommended.
+# Defaults can be restored by simply deleting this file and all drop-ins.
+#
+# Use 'systemd-analyze cat-config systemd/resolved.conf' to display the full config.
+#
+# See resolved.conf(5) for details.
+
+[Resolve]
+# Some examples of DNS servers which may be used for DNS= and FallbackDNS=:
+# Cloudflare: 1.1.1.1#cloudflare-dns.com 1.0.0.1#cloudflare-dns.com 2606:4700:4700::1111#cloudflare-dns.com 2606:4700:4700::1001#cloudflare-dns.com
+# Google: 8.8.8.8#dns.google 8.8.4.4#dns.google 2001:4860:4860::8888#dns.google 2001:4860:4860::8844#dns.google
+# Quad9: 9.9.9.9#dns.quad9.net 149.112.112.112#dns.quad9.net 2620:fe::fe#dns.quad9.net 2620:fe::9#dns.quad9.net
+#DNS=
+#FallbackDNS={{DNS_SERVERS}}
+#Domains=
+#DNSSEC={{DEFAULT_DNSSEC_MODE_STR}}
+#DNSOverTLS={{DEFAULT_DNS_OVER_TLS_MODE_STR}}
+#MulticastDNS={{DEFAULT_MDNS_MODE_STR}}
+#LLMNR={{DEFAULT_LLMNR_MODE_STR}}
+#Cache=yes
+#CacheFromLocalhost=no
+#DNSStubListener=yes
+#DNSStubListenerExtra=
+#ReadEtcHosts=yes
+#ResolveUnicastSingleLabel=no