Update dependencies
This commit is contained in:
bluepython508
459
vendor/tailscale.com/net/dns/nrpt_windows.go
generated
vendored
Normal file
459
vendor/tailscale.com/net/dns/nrpt_windows.go
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vendored
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@@ -0,0 +1,459 @@
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// 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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"fmt"
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"strings"
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"sync"
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"sync/atomic"
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"golang.org/x/sys/windows"
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"golang.org/x/sys/windows/registry"
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"tailscale.com/types/logger"
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"tailscale.com/util/dnsname"
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"tailscale.com/util/set"
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"tailscale.com/util/winutil"
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"tailscale.com/util/winutil/gp"
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)
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const (
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dnsBaseGP = `SOFTWARE\Policies\Microsoft\Windows NT\DNSClient`
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nrptBaseLocal = `SYSTEM\CurrentControlSet\Services\Dnscache\Parameters\DnsPolicyConfig`
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nrptBaseGP = `SOFTWARE\Policies\Microsoft\Windows NT\DNSClient\DnsPolicyConfig`
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nrptOverrideDNS = 0x8 // bitmask value for "use the provided override DNS resolvers"
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// Apparently NRPT rules cannot handle > 50 domains.
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nrptMaxDomainsPerRule = 50
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// This is the legacy rule ID that previous versions used when we supported
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// only a single rule. Now that we support multiple rules are required, we
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// generate their GUIDs and store them under the Tailscale registry key.
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nrptSingleRuleID = `{5abe529b-675b-4486-8459-25a634dacc23}`
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// This is the name of the registry value we use to save Rule IDs under
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// the Tailscale registry key.
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nrptRuleIDValueName = `NRPTRuleIDs`
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// This is the name of the registry value the NRPT uses for storing a rule's version number.
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nrptRuleVersionName = `Version`
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// This is the name of the registry value the NRPT uses for storing a rule's list of domains.
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nrptRuleDomsName = `Name`
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// This is the name of the registry value the NRPT uses for storing a rule's list of DNS servers.
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nrptRuleServersName = `GenericDNSServers`
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// This is the name of the registry value the NRPT uses for storing a rule's flags.
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nrptRuleFlagsName = `ConfigOptions`
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)
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// nrptRuleDatabase encapsulates access to the Windows Name Resolution Policy
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// Table (NRPT).
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type nrptRuleDatabase struct {
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logf logger.Logf
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watcher *gp.ChangeWatcher
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isGPRefreshPending atomic.Bool
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mu sync.Mutex // protects the fields below
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ruleIDs []string
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isGPDirty bool
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writeAsGP bool
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}
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func newNRPTRuleDatabase(logf logger.Logf) *nrptRuleDatabase {
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ret := &nrptRuleDatabase{logf: logf}
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ret.loadRuleSubkeyNames()
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ret.detectWriteAsGP()
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ret.watchForGPChanges()
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// Best-effort: if our NRPT rule exists, try to delete it. Unlike
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// per-interface configuration, NRPT rules survive the unclean
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// termination of the Tailscale process, and depending on the
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// rule, it may prevent us from reaching login.tailscale.com to
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// boot up. The bootstrap resolver logic will save us, but it
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// slows down start-up a bunch.
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ret.DelAllRuleKeys()
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return ret
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}
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func (db *nrptRuleDatabase) loadRuleSubkeyNames() {
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// Use the legacy rule ID if none are specified in our registry key
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db.ruleIDs = winutil.GetRegStrings(nrptRuleIDValueName, []string{nrptSingleRuleID})
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}
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// detectWriteAsGP determines which registry path should be used for writing
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// NRPT rules. If there are rules in the GP path that don't belong to us, then
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// we should use the GP path. When detectWriteAsGP determines that the desired
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// path has changed, it moves the NRPT policies as appropriate.
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func (db *nrptRuleDatabase) detectWriteAsGP() {
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db.mu.Lock()
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defer db.mu.Unlock()
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writeAsGP := false
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var err error
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defer func() {
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if err != nil {
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return
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}
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prev := db.writeAsGP
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db.writeAsGP = writeAsGP
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db.logf("nrptRuleDatabase using group policy: %v, was %v\n", writeAsGP, prev)
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// When db.watcher == nil, prev != writeAsGP because we're initializing, not
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// because anything has changed. We do not invoke
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// db.updateGroupPoliciesLocked in that case.
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if db.watcher != nil && prev != writeAsGP {
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db.updateGroupPoliciesLocked(writeAsGP)
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}
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}()
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// Get a list of all the NRPT rules under the GP subkey.
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nrptKey, err := registry.OpenKey(registry.LOCAL_MACHINE, nrptBaseGP, registry.READ)
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if err != nil {
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if err != registry.ErrNotExist {
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db.logf("Failed to open key %q with error: %v\n", nrptBaseGP, err)
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}
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// If this subkey does not exist then we definitely don't need to use the GP key.
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return
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}
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defer nrptKey.Close()
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gpSubkeyNames, err := nrptKey.ReadSubKeyNames(0)
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if err != nil {
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db.logf("Failed to list subkeys under %q with error: %v\n", nrptBaseGP, err)
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return
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}
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// Add *all* rules from the GP subkey into a set.
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gpSubkeyMap := make(set.Set[string], len(gpSubkeyNames))
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for _, gpSubkey := range gpSubkeyNames {
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gpSubkeyMap.Add(strings.ToUpper(gpSubkey))
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}
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// Remove *our* rules from the set.
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for _, ourRuleID := range db.ruleIDs {
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gpSubkeyMap.Delete(strings.ToUpper(ourRuleID))
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}
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// Any leftover rules do not belong to us. When group policy is being used
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// by something else, we must also use the GP path.
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writeAsGP = len(gpSubkeyMap) > 0
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}
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// DelAllRuleKeys removes any and all NRPT rules that are owned by Tailscale.
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func (db *nrptRuleDatabase) DelAllRuleKeys() error {
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db.mu.Lock()
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defer db.mu.Unlock()
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if err := db.delRuleKeys(db.ruleIDs); err != nil {
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return err
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}
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if err := winutil.DeleteRegValue(nrptRuleIDValueName); err != nil {
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db.logf("Error deleting registry value %q: %v", nrptRuleIDValueName, err)
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return err
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}
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db.ruleIDs = nil
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return nil
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}
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// delRuleKeys removes the NRPT rules specified by nrptRuleIDs from the
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// Windows registry. It attempts to remove the rules from both possible registry
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// keys: the local key and the group policy key.
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func (db *nrptRuleDatabase) delRuleKeys(nrptRuleIDs []string) error {
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for _, rid := range nrptRuleIDs {
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keyNameLocal := nrptBaseLocal + `\` + rid
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if err := registry.DeleteKey(registry.LOCAL_MACHINE, keyNameLocal); err != nil && err != registry.ErrNotExist {
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db.logf("Error deleting NRPT rule key %q: %v", keyNameLocal, err)
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return err
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}
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keyNameGP := nrptBaseGP + `\` + rid
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err := registry.DeleteKey(registry.LOCAL_MACHINE, keyNameGP)
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if err == nil {
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// If this deleted subkey existed under the GP key, we will need to refresh.
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db.isGPDirty = true
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} else if err != registry.ErrNotExist {
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db.logf("Error deleting NRPT rule key %q: %v", keyNameGP, err)
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return err
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}
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}
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if !db.isGPDirty {
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return nil
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}
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// If we've removed keys from the Group Policy subkey, and the DNSPolicyConfig
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// subkey is now empty, we need to remove that subkey.
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isEmpty, err := isPolicyConfigSubkeyEmpty()
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if err != nil || !isEmpty {
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return err
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}
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return registry.DeleteKey(registry.LOCAL_MACHINE, nrptBaseGP)
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}
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// isPolicyConfigSubkeyEmpty returns true if and only if the nrptBaseGP exists
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// and does not contain any values or subkeys.
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func isPolicyConfigSubkeyEmpty() (bool, error) {
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subKey, err := registry.OpenKey(registry.LOCAL_MACHINE, nrptBaseGP, registry.READ)
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if err != nil {
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if err == registry.ErrNotExist {
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return false, nil
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}
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return false, err
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}
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defer subKey.Close()
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ki, err := subKey.Stat()
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if err != nil {
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return false, err
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}
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return (ki.ValueCount == 0 && ki.SubKeyCount == 0), nil
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}
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func (db *nrptRuleDatabase) WriteSplitDNSConfig(servers []string, domains []dnsname.FQDN) error {
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db.mu.Lock()
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defer db.mu.Unlock()
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// NRPT has an undocumented restriction that each rule may only be associated
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// with a maximum of 50 domains. If we are setting rules for more domains
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// than that, we need to split domains into chunks and write out a rule per chunk.
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domainRulesLen := (len(domains) + nrptMaxDomainsPerRule - 1) / nrptMaxDomainsPerRule
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db.loadRuleSubkeyNames()
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for len(db.ruleIDs) < domainRulesLen {
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guid, err := windows.GenerateGUID()
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if err != nil {
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return err
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}
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db.ruleIDs = append(db.ruleIDs, guid.String())
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}
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// Remove any surplus rules that are no longer needed.
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ruleIDsToRemove := db.ruleIDs[domainRulesLen:]
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db.delRuleKeys(ruleIDsToRemove)
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// We need to save the list of rule IDs to our Tailscale registry key so that
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// we know which rules are ours during subsequent modifications to NRPT rules.
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ruleIDsToWrite := db.ruleIDs[:domainRulesLen]
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if len(ruleIDsToWrite) == 0 {
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if err := winutil.DeleteRegValue(nrptRuleIDValueName); err != nil {
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return err
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}
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db.ruleIDs = nil
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return nil
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}
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if err := winutil.SetRegStrings(nrptRuleIDValueName, ruleIDsToWrite); err != nil {
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return err
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}
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db.ruleIDs = ruleIDsToWrite
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curRuleID := 0
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doms := make([]string, 0, nrptMaxDomainsPerRule)
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for _, domain := range domains {
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if len(doms) == nrptMaxDomainsPerRule {
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if err := db.writeNRPTRule(db.ruleIDs[curRuleID], servers, doms); err != nil {
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return err
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}
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curRuleID++
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doms = doms[:0]
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}
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// NRPT rules must have a leading dot, which is not usual for
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// DNS search paths.
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doms = append(doms, "."+domain.WithoutTrailingDot())
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}
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if len(doms) > 0 {
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if err := db.writeNRPTRule(db.ruleIDs[curRuleID], servers, doms); err != nil {
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return err
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}
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}
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return nil
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}
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// Refresh notifies the Windows group policy engine when policies have changed.
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func (db *nrptRuleDatabase) Refresh() {
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db.mu.Lock()
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defer db.mu.Unlock()
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db.refreshLocked()
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}
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func (db *nrptRuleDatabase) refreshLocked() {
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if !db.isGPDirty {
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return
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}
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// Record that we are about to initiate a refresh.
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// (*nrptRuleDatabase).watchForGPChanges() checks this value to avoid false
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// positives.
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db.isGPRefreshPending.Store(true)
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if err := gp.RefreshMachinePolicy(true); err != nil {
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db.logf("RefreshMachinePolicy failed: %v", err)
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return
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}
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db.isGPDirty = false
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}
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func (db *nrptRuleDatabase) writeNRPTRule(ruleID string, servers, doms []string) error {
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subKeys := []string{nrptBaseLocal, nrptBaseGP}
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if !db.writeAsGP {
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// We don't want to write to the GP key, so chop nrptBaseGP off of subKeys.
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subKeys = subKeys[:1]
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}
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for _, subKeyBase := range subKeys {
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subKey := strings.Join([]string{subKeyBase, ruleID}, `\`)
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key, _, err := registry.CreateKey(registry.LOCAL_MACHINE, subKey, registry.SET_VALUE)
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if err != nil {
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return fmt.Errorf("opening %q: %w", subKey, err)
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}
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defer key.Close()
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if err := writeNRPTValues(key, strings.Join(servers, "; "), doms); err != nil {
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return err
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}
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}
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db.isGPDirty = db.writeAsGP
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return nil
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}
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func readNRPTValues(key registry.Key) (servers string, doms []string, err error) {
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doms, _, err = key.GetStringsValue(nrptRuleDomsName)
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if err != nil {
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return servers, doms, err
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}
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servers, _, err = key.GetStringValue(nrptRuleServersName)
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return servers, doms, err
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}
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func writeNRPTValues(key registry.Key, servers string, doms []string) error {
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if err := key.SetDWordValue(nrptRuleVersionName, 1); err != nil {
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return err
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}
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if err := key.SetStringsValue(nrptRuleDomsName, doms); err != nil {
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return err
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}
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if err := key.SetStringValue(nrptRuleServersName, servers); err != nil {
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return err
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}
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return key.SetDWordValue(nrptRuleFlagsName, nrptOverrideDNS)
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}
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func (db *nrptRuleDatabase) watchForGPChanges() {
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watchHandler := func() {
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// Do not invoke detectWriteAsGP when we ourselves were responsible for
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// initiating the group policy refresh.
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if db.isGPRefreshPending.CompareAndSwap(true, false) {
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return
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}
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db.logf("Computer group policies refreshed, reconfiguring NRPT rule database.")
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db.detectWriteAsGP()
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}
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watcher, err := gp.NewChangeWatcher(gp.MachinePolicy, watchHandler)
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if err != nil {
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return
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}
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db.watcher = watcher
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}
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// updateGroupPoliciesLocked updates the NRPT group policy table depending on
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// the value of writeAsGP. When writeAsGP is true, each NRPT rule is copied from
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// the local NRPT table to the group policy NRPT table. When writeAsGP is false,
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// we remove any Tailscale NRPT rules from the group policy table and, if no
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// non-Tailscale rules remain, we also delete the entire DnsPolicyConfig subkey.
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// db.mu must already be locked.
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func (db *nrptRuleDatabase) updateGroupPoliciesLocked(writeAsGP bool) {
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// Since we're updating the group policy NRPT table, we need
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// to refresh once this updateGroupPoliciesLocked is done.
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defer db.refreshLocked()
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for _, id := range db.ruleIDs {
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if writeAsGP {
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if err := copyNRPTRule(id); err != nil {
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db.logf("updateGroupPoliciesLocked: copyNRPTRule(%q) failed with error %v", id, err)
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return
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}
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} else {
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subKeyFrom := strings.Join([]string{nrptBaseGP, id}, `\`)
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if err := registry.DeleteKey(registry.LOCAL_MACHINE, subKeyFrom); err != nil && err != registry.ErrNotExist {
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db.logf("updateGroupPoliciesLocked: DeleteKey for rule %q failed with error %v", id, err)
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return
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}
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}
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db.isGPDirty = true
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}
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if writeAsGP {
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return
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}
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// Now that we have removed our rules from group policy subkey, it should
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// now be empty. Let's verify that.
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isEmpty, err := isPolicyConfigSubkeyEmpty()
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if err != nil {
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db.logf("updateGroupPoliciesLocked: isPolicyConfigSubkeyEmpty error %v", err)
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return
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}
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if !isEmpty {
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db.logf("updateGroupPoliciesLocked: policy config subkey should be empty, but isn't!")
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return
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}
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// Delete the subkey itself. Group policy will continue to override local
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// settings unless we do so.
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if err := registry.DeleteKey(registry.LOCAL_MACHINE, nrptBaseGP); err != nil {
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db.logf("updateGroupPoliciesLocked DeleteKey error %v", err)
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}
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db.isGPDirty = true
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}
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func copyNRPTRule(ruleID string) error {
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subKeyFrom := strings.Join([]string{nrptBaseLocal, ruleID}, `\`)
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subKeyTo := strings.Join([]string{nrptBaseGP, ruleID}, `\`)
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fromKey, err := registry.OpenKey(registry.LOCAL_MACHINE, subKeyFrom, registry.QUERY_VALUE)
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if err != nil {
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return err
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}
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defer fromKey.Close()
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toKey, _, err := registry.CreateKey(registry.LOCAL_MACHINE, subKeyTo, registry.WRITE)
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if err != nil {
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return err
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}
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defer toKey.Close()
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servers, doms, err := readNRPTValues(fromKey)
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if err != nil {
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return err
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}
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return writeNRPTValues(toKey, servers, doms)
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}
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func (db *nrptRuleDatabase) Close() error {
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if db.watcher == nil {
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return nil
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}
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err := db.watcher.Close()
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db.watcher = nil
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return err
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}
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Block a user