diff options
Diffstat (limited to '')
| -rw-r--r-- | src/resolve/resolved.c | 99 | ||||
| -rw-r--r-- | src/resolve/resolved.conf.in | 34 |
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 |