diff --git a/NEWS b/NEWS
index 8054d88d96..ecd12d32be 100644
--- a/NEWS
+++ b/NEWS
@@ -6,6 +6,14 @@ CHANGES WITH 236 in spe:
has been extended to also set the dummy module option numdummies=0,
resolving issues with the kernel creating dummy0.
+ * systemd-resolved now maintains a new dynamic
+ /run/systemd/resolve/stub-resolv.conf compatibility file. It is now
+ recommended to maintain /etc/resolv.conf as a symlink to this new
+ dynamic file. It points at the systemd-resolved stub DNS 127.0.0.53
+ resolver and it includes dynamically acquired search domains. This
+ achieves a more correct DNS resolution by software that bypasses
+ local DNS APIs (e.g. NSS).
+
CHANGES WITH 235:
* A new modprobe.d drop-in is now shipped by default that sets the
diff --git a/man/systemd-resolved.service.xml b/man/systemd-resolved.service.xml
index d07d1968b4..c60f474aa8 100644
--- a/man/systemd-resolved.service.xml
+++ b/man/systemd-resolved.service.xml
@@ -94,7 +94,8 @@
systemd.network5 for details
about systemd's own configuration files for DNS servers. To improve compatibility,
/etc/resolv.conf is read in order to discover configured system DNS servers, but only if it is
- not a symlink to /run/systemd/resolve/resolv.conf (see below).
+ not a symlink to /run/systemd/resolve/stub-resolv.conf or
+ /run/systemd/resolve/resolv.conf (see below).
systemd-resolved synthesizes DNS resource records (RRs) for the following cases:
@@ -164,15 +165,26 @@
<filename>/etc/resolv.conf</filename>
- Three modes of handling /etc/resolv.conf (see
+ Four modes of handling /etc/resolv.conf (see
resolv.conf5) are
supported:
+ systemd-resolved maintains the
+ /run/systemd/resolve/stub-resolv.conf file for compatibility with traditional Linux
+ programs. This file may be symlinked from /etc/resolv.conf. This file lists the 127.0.0.53
+ DNS stub (see above) as the only DNS server. It also contains a list of search domains that are in use by
+ systemd-resolved. The list of search domains is always kept up-to-date. Note that
+ /run/systemd/resolve/stub-resolv.conf should not be used directly by applications, but only
+ through a symlink from /etc/resolv.conf. This file may be symlinked from
+ /etc/resolv.conf in order to connect all local clients that bypass local DNS APIs to
+ systemd-resolved with correct search domains settings. This mode of operation is
+ recommended.
+
A static file /usr/lib/systemd/resolv.conf is provided that lists
the 127.0.0.53 DNS stub (see above) as only DNS server. This file may be symlinked from
/etc/resolv.conf in order to connect all local clients that bypass local DNS APIs to
- systemd-resolved. This mode of operation is recommended.
+ systemd-resolved. This file does not contain any search domains.
systemd-resolved maintains the
/run/systemd/resolve/resolv.conf file for compatibility with traditional Linux
diff --git a/src/resolve/resolved-resolv-conf.c b/src/resolve/resolved-resolv-conf.c
index e3d6a33409..4944e299a4 100644
--- a/src/resolve/resolved-resolv-conf.c
+++ b/src/resolve/resolved-resolv-conf.c
@@ -61,7 +61,13 @@ int manager_read_resolv_conf(Manager *m) {
return 0;
/* Is it symlinked to our own file? */
- if (stat(PRIVATE_RESOLV_CONF, &own) >= 0 &&
+ if (stat(PRIVATE_UPLINK_RESOLV_CONF, &own) >= 0 &&
+ st.st_dev == own.st_dev &&
+ st.st_ino == own.st_ino)
+ return 0;
+
+ /* Is it symlinked to our own stub file? */
+ if (stat(PRIVATE_STUB_RESOLV_CONF, &own) >= 0 &&
st.st_dev == own.st_dev &&
st.st_ino == own.st_ino)
return 0;
@@ -206,7 +212,7 @@ static void write_resolv_conf_search(
fputs_unlocked("\n", f);
}
-static int write_resolv_conf_contents(FILE *f, OrderedSet *dns, OrderedSet *domains) {
+static int write_uplink_resolv_conf_contents(FILE *f, OrderedSet *dns, OrderedSet *domains) {
Iterator i;
fputs_unlocked("# This file is managed by man:systemd-resolved(8). Do not edit.\n#\n"
@@ -234,11 +240,25 @@ static int write_resolv_conf_contents(FILE *f, OrderedSet *dns, OrderedSet *doma
return fflush_and_check(f);
}
+static int write_stub_resolv_conf_contents(FILE *f, OrderedSet *dns, OrderedSet *domains) {
+ fputs("# This file is managed by man:systemd-resolved(8). Do not edit.\n#\n"
+ "# 127.0.0.53 is the systemd-resolved stub resolver.\n"
+ "# run \"systemd-resolve --status\" to see details about the actual nameservers.\n"
+ "nameserver 127.0.0.53\n\n", f);
+
+ if (!ordered_set_isempty(domains))
+ write_resolv_conf_search(domains, f);
+
+ return fflush_and_check(f);
+}
+
int manager_write_resolv_conf(Manager *m) {
_cleanup_ordered_set_free_ OrderedSet *dns = NULL, *domains = NULL;
- _cleanup_free_ char *temp_path = NULL;
- _cleanup_fclose_ FILE *f = NULL;
+ _cleanup_free_ char *temp_path_uplink = NULL;
+ _cleanup_free_ char *temp_path_stub = NULL;
+ _cleanup_fclose_ FILE *f_uplink = NULL;
+ _cleanup_fclose_ FILE *f_stub = NULL;
int r;
assert(m);
@@ -255,28 +275,44 @@ int manager_write_resolv_conf(Manager *m) {
if (r < 0)
return log_warning_errno(r, "Failed to compile list of search domains: %m");
- r = fopen_temporary_label(PRIVATE_RESOLV_CONF, PRIVATE_RESOLV_CONF, &f, &temp_path);
+ r = fopen_temporary_label(PRIVATE_UPLINK_RESOLV_CONF, PRIVATE_UPLINK_RESOLV_CONF, &f_uplink, &temp_path_uplink);
if (r < 0)
return log_warning_errno(r, "Failed to open private resolv.conf file for writing: %m");
+ r = fopen_temporary_label(PRIVATE_STUB_RESOLV_CONF, PRIVATE_STUB_RESOLV_CONF, &f_stub, &temp_path_stub);
+ if (r < 0)
+ return log_warning_errno(r, "Failed to open private stub-resolv.conf file for writing: %m");
+ (void) fchmod(fileno(f_uplink), 0644);
+ (void) fchmod(fileno(f_stub), 0644);
- (void) fchmod(fileno(f), 0644);
-
- r = write_resolv_conf_contents(f, dns, domains);
+ r = write_uplink_resolv_conf_contents(f_uplink, dns, domains);
if (r < 0) {
log_error_errno(r, "Failed to write private resolv.conf contents: %m");
goto fail;
}
- if (rename(temp_path, PRIVATE_RESOLV_CONF) < 0) {
+ if (rename(temp_path_uplink, PRIVATE_UPLINK_RESOLV_CONF) < 0) {
r = log_error_errno(errno, "Failed to move private resolv.conf file into place: %m");
goto fail;
}
+ r = write_stub_resolv_conf_contents(f_stub, dns, domains);
+ if (r < 0) {
+ log_error_errno(r, "Failed to write private stub-resolv.conf contents: %m");
+ goto fail;
+ }
+
+ if (rename(temp_path_stub, PRIVATE_STUB_RESOLV_CONF) < 0) {
+ r = log_error_errno(errno, "Failed to move private stub-resolv.conf file into place: %m");
+ goto fail;
+ }
+
return 0;
fail:
- (void) unlink(PRIVATE_RESOLV_CONF);
- (void) unlink(temp_path);
+ (void) unlink(PRIVATE_UPLINK_RESOLV_CONF);
+ (void) unlink(temp_path_uplink);
+ (void) unlink(PRIVATE_STUB_RESOLV_CONF);
+ (void) unlink(temp_path_stub);
return r;
}
diff --git a/src/resolve/resolved-resolv-conf.h b/src/resolve/resolved-resolv-conf.h
index 75fa080e4c..6dc1afe764 100644
--- a/src/resolve/resolved-resolv-conf.h
+++ b/src/resolve/resolved-resolv-conf.h
@@ -21,7 +21,8 @@
#include "resolved-manager.h"
-#define PRIVATE_RESOLV_CONF "/run/systemd/resolve/resolv.conf"
+#define PRIVATE_UPLINK_RESOLV_CONF "/run/systemd/resolve/resolv.conf"
+#define PRIVATE_STUB_RESOLV_CONF "/run/systemd/resolve/stub-resolv.conf"
int manager_read_resolv_conf(Manager *m);
int manager_write_resolv_conf(Manager *m);
diff --git a/src/resolve/resolved.c b/src/resolve/resolved.c
index d6f916bbda..9ff877498c 100644
--- a/src/resolve/resolved.c
+++ b/src/resolve/resolved.c
@@ -117,10 +117,6 @@ int main(int argc, char *argv[]) {
sd_event_get_exit_code(m->event, &r);
finish:
- /* systemd-nspawn checks for private resolv.conf to decide whether
- or not to mount it into the container. So just delete it. */
- (void) unlink(PRIVATE_RESOLV_CONF);
-
sd_notify(false,
"STOPPING=1\n"
"STATUS=Shutting down...");
diff --git a/tmpfiles.d/etc.conf.m4 b/tmpfiles.d/etc.conf.m4
index 35e3809f57..df8d42101c 100644
--- a/tmpfiles.d/etc.conf.m4
+++ b/tmpfiles.d/etc.conf.m4
@@ -14,7 +14,7 @@ m4_ifdef(`HAVE_SMACK_RUN_LABEL',
t /etc/mtab - - - - security.SMACK64=_
)m4_dnl
m4_ifdef(`ENABLE_RESOLVE',
-L! /etc/resolv.conf - - - - ../usr/lib/systemd/resolv.conf
+L! /etc/resolv.conf - - - - ../run/systemd/resolve/stub-resolv.conf
)m4_dnl
C /etc/nsswitch.conf - - - -
m4_ifdef(`HAVE_PAM',