<option>--link-journal=try-guest</option>.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>--resolv-conf=</option></term>
+
+ <listitem><para>Configures how <filename>/etc/resolv.conf</filename> inside of the container (i.e. DNS
+ configuration synchronization from host to container) shall be handled. Takes one of <literal>off</literal>,
+ <literal>copy-host</literal>, <literal>copy-static</literal>, <literal>bind-host</literal>,
+ <literal>bind-static</literal>, <literal>delete</literal> or <literal>auto</literal>. If set to
+ <literal>off</literal> the <filename>/etc/resolv.conf</filename> file in the container is left as it is
+ included in the image, and neither modified nor bind mounted over. If set to <literal>copy-host</literal>, the
+ <filename>/etc/resolv.conf</filename> file from the host is copied into the container. Similar, if
+ <literal>bind-host</literal> is used, the file is bind mounted from the host into the container. If set to
+ <literal>copy-static</literal> the static <filename>resolv.conf</filename> file supplied with
+ <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> is
+ copied into the container, and correspondingly <literal>bind-static</literal> bind mounts it there. If set to
+ <literal>delete</literal> the <filename>/etc/resolv.conf</filename> file in the container is deleted if it
+ exists. Finally, if set to <literal>auto</literal> the file is left as it is if private networking is turned on
+ (see <option>--private-network</option>). Otherwise, if <filename>systemd-resolved.service</filename> is
+ connectible its static <filename>resolv.conf</filename> file is used, and if not the host's
+ <filename>/etc/resolv.conf</filename> file is used. In the latter cases the file is copied if the image is
+ writable, and bind mounted otherwise. It's recommended to use <literal>copy</literal> if the container shall be
+ able to make changes to the DNS configuration on its own, deviating from the host's settings. Otherwise
+ <literal>bind</literal> is preferable, as it means direct changes to <filename>/etc/resolv.conf</filename> in
+ the container are not allowed, as it is a read-only bind mount (but note that if the container has enough
+ privileges, it might simply go ahead and unmount the bind mount anyway). Note that both if the file is bind
+ mounted and if it is copied no further propagation of configuration is generally done after the one-time early
+ initialization (this is because the file is usually updated through copying and renaming). Defaults to
+ <literal>auto</literal>.</para></listitem>
+ </varlistentry>
+
<varlistentry>
<term><option>--read-only</option></term>
_USER_NAMESPACE_MODE_INVALID = -1,
} UserNamespaceMode;
+typedef enum ResolvConfMode {
+ RESOLV_CONF_OFF,
+ RESOLV_CONF_COPY_HOST,
+ RESOLV_CONF_COPY_STATIC,
+ RESOLV_CONF_BIND_HOST,
+ RESOLV_CONF_BIND_STATIC,
+ RESOLV_CONF_DELETE,
+ RESOLV_CONF_AUTO,
+ _RESOLV_CONF_MODE_MAX,
+ _RESOLV_CONF_MODE_INVALID = -1
+} ResolvConfMode;
+
typedef enum SettingsMask {
SETTING_START_MODE = UINT64_C(1) << 0,
SETTING_ENVIRONMENT = UINT64_C(1) << 1,
SETTING_NO_NEW_PRIVILEGES = UINT64_C(1) << 18,
SETTING_OOM_SCORE_ADJUST = UINT64_C(1) << 19,
SETTING_CPU_AFFINITY = UINT64_C(1) << 20,
- SETTING_RLIMIT_FIRST = UINT64_C(1) << 21, /* we define one bit per resource limit here */
- SETTING_RLIMIT_LAST = UINT64_C(1) << (21 + _RLIMIT_MAX - 1),
- _SETTINGS_MASK_ALL = (UINT64_C(1) << (21 + _RLIMIT_MAX)) - 1,
+ SETTING_RESOLV_CONF = UINT64_C(1) << 21,
+ SETTING_RLIMIT_FIRST = UINT64_C(1) << 22, /* we define one bit per resource limit here */
+ SETTING_RLIMIT_LAST = UINT64_C(1) << (22 + _RLIMIT_MAX - 1),
+ _SETTINGS_MASK_ALL = (UINT64_C(1) << (22 + _RLIMIT_MAX)) - 1,
_FORCE_ENUM_WIDTH = UINT64_MAX
} SettingsMask;
bool oom_score_adjust_set;
cpu_set_t *cpuset;
unsigned cpuset_ncpus;
+ ResolvConfMode resolv_conf;
/* [Image] */
int read_only;
CONFIG_PARSER_PROTOTYPE(config_parse_hostname);
CONFIG_PARSER_PROTOTYPE(config_parse_oom_score_adjust);
CONFIG_PARSER_PROTOTYPE(config_parse_cpu_affinity);
+CONFIG_PARSER_PROTOTYPE(config_parse_resolv_conf);
+
+const char *resolv_conf_mode_to_string(ResolvConfMode a) _const_;
+ResolvConfMode resolv_conf_mode_from_string(const char *s) _pure_;
static bool arg_oom_score_adjust_set = false;
static cpu_set_t *arg_cpuset = NULL;
static unsigned arg_cpuset_ncpus = 0;
+static ResolvConfMode arg_resolv_conf = RESOLV_CONF_AUTO;
static void help(void) {
" --link-journal=MODE Link up guest journal, one of no, auto, guest, \n"
" host, try-guest, try-host\n"
" -j Equivalent to --link-journal=try-guest\n"
+ " --resolv-conf=MODE Select mode of /etc/resolv.conf initialization\n"
" --read-only Mount the root directory read-only\n"
" --bind=PATH[:PATH[:OPTIONS]]\n"
" Bind mount a file or directory from the host into\n"
ARG_NO_NEW_PRIVILEGES,
ARG_OOM_SCORE_ADJUST,
ARG_CPU_AFFINITY,
+ ARG_RESOLV_CONF,
};
static const struct option options[] = {
{ "rlimit", required_argument, NULL, ARG_RLIMIT },
{ "oom-score-adjust", required_argument, NULL, ARG_OOM_SCORE_ADJUST },
{ "cpu-affinity", required_argument, NULL, ARG_CPU_AFFINITY },
+ { "resolv-conf", required_argument, NULL, ARG_RESOLV_CONF },
{}
};
break;
}
+ case ARG_RESOLV_CONF:
+ if (streq(optarg, "help")) {
+ DUMP_STRING_TABLE(resolv_conf_mode, ResolvConfMode, _RESOLV_CONF_MODE_MAX);
+ return 0;
+ }
+
+ arg_resolv_conf = resolv_conf_mode_from_string(optarg);
+ if (arg_resolv_conf < 0) {
+ log_error("Failed to parse /etc/resolv.conf mode: %s", optarg);
+ return -EINVAL;
+ }
+
+ arg_settings_mask |= SETTING_RESOLV_CONF;
+ break;
+
case '?':
return -EINVAL;
return 0;
}
+static int have_resolv_conf(const char *path) {
+ assert(path);
+
+ if (access(path, F_OK) < 0) {
+ if (errno == ENOENT)
+ return 0;
+
+ return log_debug_errno(errno, "Failed to determine whether '%s' is available: %m", path);
+ }
+
+ return 1;
+}
+
static int resolved_listening(void) {
_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
_cleanup_free_ char *dns_stub_listener_mode = NULL;
}
static int setup_resolv_conf(const char *dest) {
- _cleanup_free_ char *resolved = NULL, *etc = NULL;
- const char *where;
- int r, found;
+ _cleanup_free_ char *etc = NULL;
+ const char *where, *what;
+ ResolvConfMode m;
+ int r;
assert(dest);
- if (arg_private_network)
+ if (arg_resolv_conf == RESOLV_CONF_AUTO) {
+ if (arg_private_network)
+ m = RESOLV_CONF_OFF;
+ else if (have_resolv_conf(STATIC_RESOLV_CONF) > 0 && resolved_listening() > 0)
+ /* resolved is enabled on the host. In this, case bind mount its static resolv.conf file into the
+ * container, so that the container can use the host's resolver. Given that network namespacing is
+ * disabled it's only natural of the container also uses the host's resolver. It also has the big
+ * advantage that the container will be able to follow the host's DNS server configuration changes
+ * transparently. */
+ m = RESOLV_CONF_BIND_STATIC;
+ else if (have_resolv_conf("/etc/resolv.conf") > 0)
+ m = arg_read_only && arg_volatile_mode != VOLATILE_YES ? RESOLV_CONF_BIND_HOST : RESOLV_CONF_COPY_HOST;
+ else
+ m = arg_read_only && arg_volatile_mode != VOLATILE_YES ? RESOLV_CONF_OFF : RESOLV_CONF_DELETE;
+ } else
+ m = arg_resolv_conf;
+
+ if (m == RESOLV_CONF_OFF)
return 0;
r = chase_symlinks("/etc", dest, CHASE_PREFIX_ROOT, &etc);
}
where = strjoina(etc, "/resolv.conf");
- found = chase_symlinks(where, dest, CHASE_NONEXISTENT, &resolved);
- if (found < 0) {
- log_warning_errno(found, "Failed to resolve /etc/resolv.conf path in container, ignoring: %m");
+
+ if (m == RESOLV_CONF_DELETE) {
+ if (unlink(where) < 0)
+ log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_WARNING, errno, "Failed to remove '%s', ignoring: %m", where);
+
return 0;
}
- if (access(STATIC_RESOLV_CONF, F_OK) >= 0 &&
- resolved_listening() > 0) {
+ if (IN_SET(m, RESOLV_CONF_BIND_STATIC, RESOLV_CONF_COPY_STATIC))
+ what = STATIC_RESOLV_CONF;
+ else
+ what = "/etc/resolv.conf";
- /* resolved is enabled on the host. In this, case bind mount its static resolv.conf file into the
- * container, so that the container can use the host's resolver. Given that network namespacing is
- * disabled it's only natural of the container also uses the host's resolver. It also has the big
- * advantage that the container will be able to follow the host's DNS server configuration changes
- * transparently. */
+ if (IN_SET(m, RESOLV_CONF_BIND_HOST, RESOLV_CONF_BIND_STATIC)) {
+ _cleanup_free_ char *resolved = NULL;
+ int found;
+
+ found = chase_symlinks(where, dest, CHASE_NONEXISTENT, &resolved);
+ if (found < 0) {
+ log_warning_errno(found, "Failed to resolve /etc/resolv.conf path in container, ignoring: %m");
+ return 0;
+ }
if (found == 0) /* missing? */
(void) touch(resolved);
- r = mount_verbose(LOG_DEBUG, STATIC_RESOLV_CONF, resolved, NULL, MS_BIND, NULL);
+ r = mount_verbose(LOG_WARNING, what, resolved, NULL, MS_BIND, NULL);
if (r >= 0)
return mount_verbose(LOG_ERR, NULL, resolved, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY|MS_NOSUID|MS_NODEV, NULL);
}
/* If that didn't work, let's copy the file */
- r = copy_file("/etc/resolv.conf", where, O_TRUNC|O_NOFOLLOW, 0644, 0, COPY_REFLINK);
+ r = copy_file(what, where, O_TRUNC|O_NOFOLLOW, 0644, 0, COPY_REFLINK);
if (r < 0) {
/* If the file already exists as symlink, let's suppress the warning, under the assumption that
* resolved or something similar runs inside and the symlink points there.
*
* If the disk image is read-only, there's also no point in complaining.
*/
- log_full_errno(IN_SET(r, -ELOOP, -EROFS, -EACCES, -EPERM) ? LOG_DEBUG : LOG_WARNING, r,
+ log_full_errno(!IN_SET(RESOLV_CONF_COPY_HOST, RESOLV_CONF_COPY_STATIC) && IN_SET(r, -ELOOP, -EROFS, -EACCES, -EPERM) ? LOG_DEBUG : LOG_WARNING, r,
"Failed to copy /etc/resolv.conf to %s, ignoring: %m", where);
return 0;
}
}
}
+ if ((arg_settings_mask & SETTING_RESOLV_CONF) == 0 &&
+ settings->resolv_conf != _RESOLV_CONF_MODE_INVALID)
+ arg_resolv_conf = settings->resolv_conf;
+
return 0;
}
projects / thirdparty / systemd.git / commitdiff
