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2b3e533048
This is step 4 of making syspolicy a build-time feature. This adds a policyclient.Get() accessor to return the correct implementation to use: either the real one, or the no-op one. (A third type, a static one for testing, also exists, so in general a policyclient.Client should be plumbed around and not always fetched via policyclient.Get whenever possible, especially if tests need to use alternate syspolicy) Updates #16998 Updates #12614 Change-Id: Iaf19670744a596d5918acfa744f5db4564272978 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
80 lines
1.9 KiB
Go
80 lines
1.9 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package dns
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import (
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"bytes"
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"fmt"
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"os"
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"tailscale.com/control/controlknobs"
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"tailscale.com/health"
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"tailscale.com/types/logger"
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"tailscale.com/util/syspolicy/policyclient"
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)
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type kv struct {
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k, v string
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}
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func (kv kv) String() string {
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return fmt.Sprintf("%s=%s", kv.k, kv.v)
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}
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// NewOSConfigurator created a new OS configurator.
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//
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// The health tracker may be nil; the knobs may be nil and are ignored on this platform.
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func NewOSConfigurator(logf logger.Logf, health *health.Tracker, _ policyclient.Client, _ *controlknobs.Knobs, interfaceName string) (OSConfigurator, error) {
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return newOSConfigurator(logf, health, interfaceName,
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newOSConfigEnv{
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rcIsResolvd: rcIsResolvd,
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fs: directFS{},
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})
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}
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// newOSConfigEnv are the funcs newOSConfigurator needs, pulled out for testing.
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type newOSConfigEnv struct {
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fs directFS
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rcIsResolvd func(resolvConfContents []byte) bool
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}
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func newOSConfigurator(logf logger.Logf, health *health.Tracker, interfaceName string, env newOSConfigEnv) (ret OSConfigurator, err error) {
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var debug []kv
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dbg := func(k, v string) {
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debug = append(debug, kv{k, v})
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}
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defer func() {
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if ret != nil {
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dbg("ret", fmt.Sprintf("%T", ret))
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}
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logf("dns: %v", debug)
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}()
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bs, err := env.fs.ReadFile(resolvConf)
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if os.IsNotExist(err) {
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dbg("rc", "missing")
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return newDirectManager(logf, health), nil
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}
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if err != nil {
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return nil, fmt.Errorf("reading /etc/resolv.conf: %w", err)
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}
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if env.rcIsResolvd(bs) {
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dbg("resolvd", "yes")
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return newResolvdManager(logf, interfaceName)
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}
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dbg("resolvd", "missing")
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return newDirectManager(logf, health), nil
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}
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func rcIsResolvd(resolvConfContents []byte) bool {
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// If we have the string "# resolvd:" in resolv.conf resolvd(8) is
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// managing things.
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if bytes.Contains(resolvConfContents, []byte("# resolvd:")) {
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return true
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}
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return false
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}
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