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net/dns: detect when libnss_resolve is used

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Having `127.0.0.53` is not the only way to use `systemd-resolved`. An
alternative way is to enable `libnss_resolve` module, which seems to now
be used by default on Debian 12 bookworm.

Fixes #8549

Signed-off-by: Anton Tolchanov <anton@tailscale.com>
This commit is contained in:
Anton Tolchanov
2023-07-18 12:43:42 +02:00
committed by Anton Tolchanov
parent efd6d90dd7
commit 388b124513
2 changed files with 91 additions and 21 deletions
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66
net/dns/manager_linux_test.go
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@@ -70,7 +70,7 @@ func TestLinuxDNSMode(t *testing.T) {
{
name: "resolved_alone_without_ping",
env: env(resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53")),
wantLog: "dns: ResolvConfMode error: dbus property not found\ndns: [rc=resolved nm=no resolv-conf-mode=error ret=systemd-resolved]",
wantLog: "dns: ResolvConfMode error: dbus property not found\ndns: [rc=resolved resolved=file nm=no resolv-conf-mode=error ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@@ -78,16 +78,46 @@ func TestLinuxDNSMode(t *testing.T) {
env: env(
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedRunning()),
wantLog: "dns: [resolved-ping=yes rc=resolved nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
name: "resolved_and_nsswitch_resolve",
env: env(
resolvDotConf("# Managed by systemd-resolved", "nameserver 1.1.1.1"),
resolvedRunning(),
nsswitchDotConf("hosts: files resolve [!UNAVAIL=return] dns"),
),
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=nss nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
name: "resolved_and_nsswitch_dns",
env: env(
resolvDotConf("# Managed by systemd-resolved", "nameserver 1.1.1.1"),
resolvedRunning(),
nsswitchDotConf("hosts: files dns resolve [!UNAVAIL=return]"),
),
wantLog: "dns: resolvedIsActuallyResolver error: resolv.conf doesn't point to systemd-resolved; points to [1.1.1.1]\ndns: [resolved-ping=yes rc=resolved resolved=not-in-use ret=direct]",
want: "direct",
},
{
name: "resolved_and_nsswitch_none",
env: env(
resolvDotConf("# Managed by systemd-resolved", "nameserver 1.1.1.1"),
resolvedRunning(),
nsswitchDotConf("hosts:"),
),
wantLog: "dns: resolvedIsActuallyResolver error: resolv.conf doesn't point to systemd-resolved; points to [1.1.1.1]\ndns: [resolved-ping=yes rc=resolved resolved=not-in-use ret=direct]",
want: "direct",
},
{
name: "resolved_and_networkmanager_not_using_resolved",
env: env(
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedRunning(),
nmRunning("1.2.3", false)),
wantLog: "dns: [resolved-ping=yes rc=resolved nm=yes nm-resolved=no resolv-conf-mode=fortests ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=yes nm-resolved=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@@ -96,7 +126,7 @@ func TestLinuxDNSMode(t *testing.T) {
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedRunning(),
nmRunning("1.26.2", true)),
wantLog: "dns: [resolved-ping=yes rc=resolved nm=yes nm-resolved=yes nm-safe=yes ret=network-manager]",
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=yes nm-resolved=yes nm-safe=yes ret=network-manager]",
want: "network-manager",
},
{
@@ -105,7 +135,7 @@ func TestLinuxDNSMode(t *testing.T) {
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedRunning(),
nmRunning("1.27.0", true)),
wantLog: "dns: [resolved-ping=yes rc=resolved nm=yes nm-resolved=yes nm-safe=no resolv-conf-mode=fortests ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=yes nm-resolved=yes nm-safe=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@@ -114,7 +144,7 @@ func TestLinuxDNSMode(t *testing.T) {
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedRunning(),
nmRunning("1.22.0", true)),
wantLog: "dns: [resolved-ping=yes rc=resolved nm=yes nm-resolved=yes nm-safe=no resolv-conf-mode=fortests ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=yes nm-resolved=yes nm-safe=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
// Regression tests for extreme corner cases below.
@@ -140,7 +170,7 @@ func TestLinuxDNSMode(t *testing.T) {
"nameserver 127.0.0.53",
"nameserver 127.0.0.53"),
resolvedRunning()),
wantLog: "dns: [resolved-ping=yes rc=resolved nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@@ -155,7 +185,7 @@ func TestLinuxDNSMode(t *testing.T) {
"# run \"systemd-resolve --status\" to see details about the actual nameservers.",
"nameserver 127.0.0.53"),
resolvedRunning()),
wantLog: "dns: [resolved-ping=yes rc=resolved nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@@ -170,7 +200,7 @@ func TestLinuxDNSMode(t *testing.T) {
"# 127.0.0.53 is the systemd-resolved stub resolver.",
"# run \"systemd-resolve --status\" to see details about the actual nameservers.",
"nameserver 127.0.0.53")),
wantLog: "dns: ResolvConfMode error: dbus property not found\ndns: [rc=resolved nm=no resolv-conf-mode=error ret=systemd-resolved]",
wantLog: "dns: ResolvConfMode error: dbus property not found\ndns: [rc=resolved resolved=file nm=no resolv-conf-mode=error ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@@ -182,7 +212,7 @@ func TestLinuxDNSMode(t *testing.T) {
"options edns0 trust-ad"),
resolvedRunning(),
nmRunning("1.32.12", true)),
wantLog: "dns: [resolved-ping=yes rc=nm nm-resolved=yes nm-safe=no resolv-conf-mode=fortests ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=nm resolved=file nm-resolved=yes nm-safe=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@@ -193,7 +223,7 @@ func TestLinuxDNSMode(t *testing.T) {
"nameserver 127.0.0.53",
"options edns0 trust-ad"),
nmRunning("1.32.12", true)),
wantLog: "dns: ResolvConfMode error: dbus property not found\ndns: [rc=nm nm-resolved=yes nm-safe=no resolv-conf-mode=error ret=systemd-resolved]",
wantLog: "dns: ResolvConfMode error: dbus property not found\ndns: [rc=nm resolved=file nm-resolved=yes nm-safe=no resolv-conf-mode=error ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@@ -205,7 +235,7 @@ func TestLinuxDNSMode(t *testing.T) {
"options edns0 trust-ad"),
resolvedRunning(),
nmRunning("1.26.3", true)),
wantLog: "dns: [resolved-ping=yes rc=nm nm-resolved=yes nm-safe=yes ret=network-manager]",
wantLog: "dns: [resolved-ping=yes rc=nm resolved=file nm-resolved=yes nm-safe=yes ret=network-manager]",
want: "network-manager",
},
{
@@ -216,7 +246,7 @@ func TestLinuxDNSMode(t *testing.T) {
"nameserver 127.0.0.53",
"options edns0 trust-ad"),
resolvedRunning()),
wantLog: "dns: [resolved-ping=yes rc=nm nm-resolved=yes nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=nm resolved=file nm-resolved=yes nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@@ -227,7 +257,7 @@ func TestLinuxDNSMode(t *testing.T) {
"search lan",
"nameserver 127.0.0.53"),
resolvedRunning()),
wantLog: "dns: [resolved-ping=yes rc=nm nm-resolved=yes nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=nm resolved=file nm-resolved=yes nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
{
@@ -237,7 +267,7 @@ func TestLinuxDNSMode(t *testing.T) {
resolvDotConf("# Managed by systemd-resolved", "nameserver 127.0.0.53"),
resolvedDbusProperty(),
)),
wantLog: "dns: [resolved-ping=yes rc=resolved nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
wantLog: "dns: [resolved-ping=yes rc=resolved resolved=file nm=no resolv-conf-mode=fortests ret=systemd-resolved]",
want: "systemd-resolved",
},
}
@@ -380,6 +410,12 @@ func resolvDotConf(ss ...string) envOption {
})
}
func nsswitchDotConf(ss ...string) envOption {
return envOpt(func(b *envBuilder) {
b.fs["/etc/nsswitch.conf"] = strings.Join(ss, "\n")
})
}
// resolvedRunning returns an option that makes resolved reply to a dbusPing
// and the ResolvConfMode property.
func resolvedRunning() envOption {