/* SPDX-License-Identifier: LGPL-2.1+ */
#include <resolv.h>
-#include <stdio_ext.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
#include "alloc-util.h"
#include "dns-domain.h"
#include "fd-util.h"
-#include "fileio-label.h"
#include "fileio.h"
+#include "fs-util.h"
#include "ordered-set.h"
#include "resolved-conf.h"
#include "resolved-dns-server.h"
#include "resolved-resolv-conf.h"
+#include "stat-util.h"
#include "string-util.h"
#include "strv.h"
-
-/* A resolv.conf file containing the DNS server and domain data we learnt from uplink, i.e. the full uplink data */
-#define PRIVATE_UPLINK_RESOLV_CONF "/run/systemd/resolve/resolv.conf"
-
-/* A resolv.conf file containing the domain data we learnt from uplink, but our own DNS server address. */
-#define PRIVATE_STUB_RESOLV_CONF "/run/systemd/resolve/stub-resolv.conf"
-
-/* A static resolv.conf file containing no domains, but only our own DNS server address */
-#define PRIVATE_STATIC_RESOLV_CONF ROOTLIBEXECDIR "/resolv.conf"
+#include "tmpfile-util-label.h"
int manager_check_resolv_conf(const Manager *m) {
- const char *path;
- struct stat st;
- int r;
+ struct stat st, own;
assert(m);
/* This warns only when our stub listener is disabled and /etc/resolv.conf is a symlink to
- * PRIVATE_STATIC_RESOLV_CONF or PRIVATE_STUB_RESOLV_CONF. */
+ * PRIVATE_STATIC_RESOLV_CONF. */
if (m->dns_stub_listener_mode != DNS_STUB_LISTENER_NO)
return 0;
- r = stat("/etc/resolv.conf", &st);
- if (r < 0) {
+ if (stat("/etc/resolv.conf", &st) < 0) {
if (errno == ENOENT)
return 0;
return log_warning_errno(errno, "Failed to stat /etc/resolv.conf: %m");
}
- FOREACH_STRING(path,
- PRIVATE_STUB_RESOLV_CONF,
- PRIVATE_STATIC_RESOLV_CONF) {
-
- struct stat own;
-
- /* Is it symlinked to our own uplink file? */
- if (stat(path, &own) >= 0 &&
- st.st_dev == own.st_dev &&
- st.st_ino == own.st_ino) {
- log_warning("DNSStubListener= is disabled, but /etc/resolv.conf is a symlink to %s "
- "which expects DNSStubListener= to be enabled.", path);
- return -EOPNOTSUPP;
- }
- }
+ /* Is it symlinked to our own uplink file? */
+ if (stat(PRIVATE_STATIC_RESOLV_CONF, &own) >= 0 &&
+ st.st_dev == own.st_dev &&
+ st.st_ino == own.st_ino)
+ return log_warning_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
+ "DNSStubListener= is disabled, but /etc/resolv.conf is a symlink to "
+ PRIVATE_STATIC_RESOLV_CONF " which expects DNSStubListener= to be enabled.");
return 0;
}
}
/* Have we already seen the file? */
- if (timespec_load(&st.st_mtim) == m->resolv_conf_mtime)
+ if (stat_inode_unmodified(&st, &m->resolv_conf_stat))
return 0;
if (file_is_our_own(&st))
log_syntax(NULL, LOG_DEBUG, "/etc/resolv.conf", n, 0, "Ignoring resolv.conf line: %s", l);
}
- m->resolv_conf_mtime = timespec_load(&st.st_mtim);
+ m->resolv_conf_stat = st;
/* Flush out all servers and search domains that are still
* marked. Those are then ones that didn't appear in the new
}
static void write_resolv_conf_server(DnsServer *s, FILE *f, unsigned *count) {
+ DnsScope *scope;
+
assert(s);
assert(f);
assert(count);
return;
}
- /* Check if the DNS server is limited to particular domains;
- * resolv.conf does not have a syntax to express that, so it must not
- * appear as a global name server to avoid routing unrelated domains to
- * it (which is a privacy violation, will most probably fail anyway,
- * and adds unnecessary load) */
- if (dns_server_limited_domains(s)) {
- log_debug("DNS server %s has route-only domains, not using as global name server", dns_server_string(s));
+ /* Check if the scope this DNS server belongs to is suitable as 'default' route for lookups; resolv.conf does
+ * not have a syntax to express that, so it must not appear as a global name server to avoid routing unrelated
+ * domains to it (which is a privacy violation, will most probably fail anyway, and adds unnecessary load) */
+ scope = dns_server_scope(s);
+ if (scope && !dns_scope_is_default_route(scope)) {
+ log_debug("Scope of DNS server %s has only route-only domains, not using as global name server", dns_server_string(s));
return;
}
static void write_resolv_conf_search(
OrderedSet *domains,
FILE *f) {
- unsigned length = 0, count = 0;
- Iterator i;
char *domain;
assert(domains);
fputs("search", f);
- ORDERED_SET_FOREACH(domain, domains, i) {
- if (++count > MAXDNSRCH) {
- fputs("\n# Too many search domains configured, remaining ones ignored.", f);
- break;
- }
- length += strlen(domain) + 1;
- if (length > 256) {
- fputs("\n# Total length of all search domains is too long, remaining ones ignored.", f);
- break;
- }
+ ORDERED_SET_FOREACH(domain, domains) {
fputc(' ', f);
fputs(domain, f);
}
}
static int write_uplink_resolv_conf_contents(FILE *f, OrderedSet *dns, OrderedSet *domains) {
- Iterator i;
fputs("# This file is managed by man:systemd-resolved(8). Do not edit.\n"
"#\n"
"# This is a dynamic resolv.conf file for connecting local clients directly to\n"
"# all known uplink DNS servers. This file lists all configured search domains.\n"
"#\n"
- "# Third party programs must not access this file directly, but only through the\n"
- "# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,\n"
- "# replace this symlink by a static file or a different symlink.\n"
+ "# Third party programs should typically not access this file directly, but only\n"
+ "# through the symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a\n"
+ "# different way, replace this symlink by a static file or a different symlink.\n"
"#\n"
"# See man:systemd-resolved.service(8) for details about the supported modes of\n"
"# operation for /etc/resolv.conf.\n"
unsigned count = 0;
DnsServer *s;
- ORDERED_SET_FOREACH(s, dns, i)
+ ORDERED_SET_FOREACH(s, dns)
write_resolv_conf_server(s, f, &count);
}
}
static int write_stub_resolv_conf_contents(FILE *f, OrderedSet *dns, OrderedSet *domains) {
- fputs_unlocked("# This file is managed by man:systemd-resolved(8). Do not edit.\n"
- "#\n"
- "# This is a dynamic resolv.conf file for connecting local clients to the\n"
- "# internal DNS stub resolver of systemd-resolved. This file lists all\n"
- "# configured search domains.\n"
- "#\n"
- "# Run \"resolvectl status\" to see details about the uplink DNS servers\n"
- "# currently in use.\n"
- "#\n"
- "# Third party programs must not access this file directly, but only through the\n"
- "# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,\n"
- "# replace this symlink by a static file or a different symlink.\n"
- "#\n"
- "# See man:systemd-resolved.service(8) for details about the supported modes of\n"
- "# operation for /etc/resolv.conf.\n"
- "\n"
- "nameserver 127.0.0.53\n", f);
+ fputs("# This file is managed by man:systemd-resolved(8). Do not edit.\n"
+ "#\n"
+ "# This is a dynamic resolv.conf file for connecting local clients to the\n"
+ "# internal DNS stub resolver of systemd-resolved. This file lists all\n"
+ "# configured search domains.\n"
+ "#\n"
+ "# Run \"resolvectl status\" to see details about the uplink DNS servers\n"
+ "# currently in use.\n"
+ "#\n"
+ "# Third party programs should typically not access this file directly, but only\n"
+ "# through the symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a\n"
+ "# different way, replace this symlink by a static file or a different symlink.\n"
+ "#\n"
+ "# See man:systemd-resolved.service(8) for details about the supported modes of\n"
+ "# operation for /etc/resolv.conf.\n"
+ "\n"
+ "nameserver 127.0.0.53\n"
+ "options edns0 trust-ad\n", f);
if (!ordered_set_isempty(domains))
write_resolv_conf_search(domains, f);
}
int manager_write_resolv_conf(Manager *m) {
-
_cleanup_ordered_set_free_ OrderedSet *dns = NULL, *domains = NULL;
_cleanup_free_ char *temp_path_uplink = NULL, *temp_path_stub = NULL;
_cleanup_fclose_ FILE *f_uplink = NULL, *f_stub = NULL;
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");
+ return log_warning_errno(r, "Failed to open new %s for writing: %m", PRIVATE_UPLINK_RESOLV_CONF);
- (void) __fsetlocking(f_uplink, FSETLOCKING_BYCALLER);
(void) fchmod(fileno(f_uplink), 0644);
- 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) __fsetlocking(f_stub, FSETLOCKING_BYCALLER);
- (void) fchmod(fileno(f_stub), 0644);
-
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");
+ log_error_errno(r, "Failed to write new %s: %m", PRIVATE_UPLINK_RESOLV_CONF);
goto fail;
}
- 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;
- }
+ if (m->dns_stub_listener_mode != DNS_STUB_LISTENER_NO) {
+ r = fopen_temporary_label(PRIVATE_STUB_RESOLV_CONF, PRIVATE_STUB_RESOLV_CONF, &f_stub, &temp_path_stub);
+ if (r < 0) {
+ log_warning_errno(r, "Failed to open new %s for writing: %m", PRIVATE_STUB_RESOLV_CONF);
+ 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;
- }
+ (void) fchmod(fileno(f_stub), 0644);
- 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;
+ r = write_stub_resolv_conf_contents(f_stub, dns, domains);
+ if (r < 0) {
+ log_error_errno(r, "Failed to write new %s: %m", PRIVATE_STUB_RESOLV_CONF);
+ goto fail;
+ }
+
+ if (rename(temp_path_stub, PRIVATE_STUB_RESOLV_CONF) < 0)
+ r = log_error_errno(errno, "Failed to move new %s into place: %m", PRIVATE_STUB_RESOLV_CONF);
+
+ } else {
+ r = symlink_atomic(basename(PRIVATE_UPLINK_RESOLV_CONF), PRIVATE_STUB_RESOLV_CONF);
+ if (r < 0)
+ log_error_errno(r, "Failed to symlink %s: %m", PRIVATE_STUB_RESOLV_CONF);
}
- return 0;
+ if (rename(temp_path_uplink, PRIVATE_UPLINK_RESOLV_CONF) < 0)
+ r = log_error_errno(errno, "Failed to move new %s into place: %m", PRIVATE_UPLINK_RESOLV_CONF);
-fail:
- (void) unlink(PRIVATE_UPLINK_RESOLV_CONF);
- (void) unlink(temp_path_uplink);
- (void) unlink(PRIVATE_STUB_RESOLV_CONF);
- (void) unlink(temp_path_stub);
+ fail:
+ if (r < 0) {
+ /* Something went wrong, perform cleanup... */
+ (void) unlink(temp_path_uplink);
+ (void) unlink(temp_path_stub);
+ }
return r;
}
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