cmd/tailscale, ipn: add start of remote-config supportbrafitz/remote-config

Updates tailscale/corp#18043

Change-Id: I1d19e7ccb16ade93468cbc5698171e04f9539b76
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

9 files changed, 73 insertions, 1 deletions

diff --git a/cmd/tailscale/cli/set.go b/cmd/tailscale/cli/set.go
index 02d4f5a06..8048b405b 100644
--- a/cmd/tailscale/cli/set.go
+++ b/cmd/tailscale/cli/set.go
@@ -56,6 +56,7 @@ type setArgsT struct {
 	updateCheck            bool
 	updateApply            bool
 	postureChecking        bool
+	remoteConfig           bool
 }
 
 func newSetFlagSet(goos string, setArgs *setArgsT) *flag.FlagSet {
@@ -76,6 +77,7 @@ func newSetFlagSet(goos string, setArgs *setArgsT) *flag.FlagSet {
 	setf.BoolVar(&setArgs.updateApply, "auto-update", false, "automatically update to the latest available version")
 	setf.BoolVar(&setArgs.postureChecking, "posture-checking", false, "HIDDEN: allow management plane to gather device posture information")
 	setf.BoolVar(&setArgs.runWebClient, "webclient", false, "run a web interface for managing this node, served over Tailscale at port 5252")
+	setf.BoolVar(&setArgs.remoteConfig, "remote-config", false, "HIDDEN: allow talinet admins to manage this node's settings")
 
 	if safesocket.GOOSUsesPeerCreds(goos) {
 		setf.StringVar(&setArgs.opUser, "operator", "", "Unix username to allow to operate on tailscaled without sudo")
@@ -116,6 +118,7 @@ func runSet(ctx context.Context, args []string) (retErr error) {
 			Hostname:               setArgs.hostname,
 			OperatorUser:           setArgs.opUser,
 			ForceDaemon:            setArgs.forceDaemon,
+			RemoteConfig:           setArgs.remoteConfig,
 			AutoUpdate: ipn.AutoUpdatePrefs{
 				Check: setArgs.updateCheck,
 				Apply: opt.NewBool(setArgs.updateApply),
@@ -148,6 +151,7 @@ func runSet(ctx context.Context, args []string) (retErr error) {
 			advertiseRoutesSet = true
 		}
 	})
+
 	if maskedPrefs.IsEmpty() {
 		return flag.ErrHelp
 	}
diff --git a/cmd/tailscale/cli/up.go b/cmd/tailscale/cli/up.go
index 43f36f819..3c6eba84b 100644
--- a/cmd/tailscale/cli/up.go
+++ b/cmd/tailscale/cli/up.go
@@ -723,6 +723,7 @@ func init() {
 	addPrefFlagMapping("auto-update", "AutoUpdate.Apply")
 	addPrefFlagMapping("advertise-connector", "AppConnector")
 	addPrefFlagMapping("posture-checking", "PostureChecking")
+	addPrefFlagMapping("remote-config", "RemoteConfig")
 }
 
 func addPrefFlagMapping(flagName string, prefNames ...string) {
diff --git a/ipn/ipn_clone.go b/ipn/ipn_clone.go
index 40cc44296..01f83ecff 100644
--- a/ipn/ipn_clone.go
+++ b/ipn/ipn_clone.go
@@ -56,6 +56,7 @@ var _PrefsCloneNeedsRegeneration = Prefs(struct {
 	AppConnector           AppConnectorPrefs
 	PostureChecking        bool
 	NetfilterKind          string
+	RemoteConfig           bool
 	Persist                *persist.Persist
 }{})
 
diff --git a/ipn/ipn_view.go b/ipn/ipn_view.go
index 18436867d..3f9c93beb 100644
--- a/ipn/ipn_view.go
+++ b/ipn/ipn_view.go
@@ -91,6 +91,7 @@ func (v PrefsView) AutoUpdate() AutoUpdatePrefs           { return v.ж.AutoUpda
 func (v PrefsView) AppConnector() AppConnectorPrefs       { return v.ж.AppConnector }
 func (v PrefsView) PostureChecking() bool                 { return v.ж.PostureChecking }
 func (v PrefsView) NetfilterKind() string                 { return v.ж.NetfilterKind }
+func (v PrefsView) RemoteConfig() bool                    { return v.ж.RemoteConfig }
 func (v PrefsView) Persist() persist.PersistView          { return v.ж.Persist.View() }
 
 // A compilation failure here means this code must be regenerated, with the command at the top of this file.
@@ -121,6 +122,7 @@ var _PrefsViewNeedsRegeneration = Prefs(struct {
 	AppConnector           AppConnectorPrefs
 	PostureChecking        bool
 	NetfilterKind          string
+	RemoteConfig           bool
 	Persist                *persist.Persist
 }{})
 
diff --git a/ipn/ipnlocal/c2n.go b/ipn/ipnlocal/c2n.go
index 9e6af14de..a76014351 100644
--- a/ipn/ipnlocal/c2n.go
+++ b/ipn/ipnlocal/c2n.go
@@ -26,9 +26,13 @@ import (
 	"tailscale.com/clientupdate"
 	"tailscale.com/envknob"
 	"tailscale.com/ipn"
+	"tailscale.com/net/netmon"
 	"tailscale.com/net/sockstats"
 	"tailscale.com/posture"
 	"tailscale.com/tailcfg"
+	"tailscale.com/types/logger"
+	"tailscale.com/types/logid"
+	"tailscale.com/types/ptr"
 	"tailscale.com/util/clientmetric"
 	"tailscale.com/util/goroutines"
 	"tailscale.com/util/set"
@@ -72,6 +76,10 @@ var c2nHandlers = map[methodAndPath]c2nHandler{
 
 	// Linux netfilter.
 	req("POST /netfilter-kind"): handleC2NSetNetfilterKind,
+
+	// Remote config
+	req("/remote-config/prefs"): handleC2NRemoteConfigPrefs,
+	// TODO(bradfitz): more (but not all) LocalAPI proxies for remote-config
 }
 
 type c2nHandler func(*LocalBackend, http.ResponseWriter, *http.Request)
@@ -569,3 +577,33 @@ func handleC2NTLSCertStatus(b *LocalBackend, w http.ResponseWriter, r *http.Requ
 
 	writeJSON(w, ret)
 }
+
+// NewC2NLocalAPIHandler is initialized by the localapi package's init func.
+// It returns a new http.Handler that serves LocalAPI for c2n.
+var NewC2NLocalAPIHandler func(b *LocalBackend, logf logger.Logf, netMon *netmon.Monitor, logID logid.PublicID) http.Handler
+
+func handleC2NRemoteConfigPrefs(b *LocalBackend, w http.ResponseWriter, r *http.Request) {
+	prefs := b.Prefs()
+	if !prefs.Valid() || !prefs.RemoteConfig() {
+		http.Error(w, "remote config not enabled", http.StatusForbidden)
+		return
+	}
+	if NewC2NLocalAPIHandler == nil {
+		http.Error(w, "remote config not wired up", http.StatusInternalServerError)
+		return
+	}
+	var newPath string
+	switch r.URL.Path {
+	case "/remote-config/prefs":
+		newPath = "/localapi/v0/prefs"
+	default:
+		http.Error(w, "unsupported path", http.StatusBadRequest)
+		return
+	}
+	r2 := r.WithContext(r.Context())
+	r2.URL = ptr.To(*r.URL) // shallow clone
+	r2.URL.Path = newPath
+
+	h := NewC2NLocalAPIHandler(b, b.logf, b.sys.NetMon.Get(), b.backendLogID)
+	h.ServeHTTP(w, r2)
+}
diff --git a/ipn/localapi/localapi.go b/ipn/localapi/localapi.go
index f68f0a282..dd5b0c7bb 100644
--- a/ipn/localapi/localapi.go
+++ b/ipn/localapi/localapi.go
@@ -153,6 +153,16 @@ func NewHandler(b *ipnlocal.LocalBackend, logf logger.Logf, netMon *netmon.Monit
 	return &Handler{b: b, logf: logf, netMon: netMon, backendLogID: logID, clock: tstime.StdClock{}}
 }
 
+func init() {
+	ipnlocal.NewC2NLocalAPIHandler = func(b *ipnlocal.LocalBackend, logf logger.Logf, netMon *netmon.Monitor, logID logid.PublicID) http.Handler {
+		h := NewHandler(b, logf, netMon, logID)
+		h.PermitRead, h.PermitWrite = true, true
+		h.PermitCert = false
+		h.ConnIdentity = &ipnauth.ConnIdentity{}
+		return h
+	}
+}
+
 type Handler struct {
 	// RequiredPassword, if non-empty, forces all HTTP
 	// requests to have HTTP basic auth with this password.
diff --git a/ipn/prefs.go b/ipn/prefs.go
index 7bfbd613f..cae9e1696 100644
--- a/ipn/prefs.go
+++ b/ipn/prefs.go
@@ -222,6 +222,10 @@ type Prefs struct {
 	// Linux-only.
 	NetfilterKind string
 
+	// RemoteConfig specifies whether to allow the control server to
+	// manage this node's settings.
+	RemoteConfig bool
+
 	// The Persist field is named 'Config' in the file for backward
 	// compatibility with earlier versions.
 	// TODO(apenwarr): We should move this out of here, it's not a pref.
@@ -293,6 +297,7 @@ type MaskedPrefs struct {
 	AppConnectorSet           bool                `json:",omitempty"`
 	PostureCheckingSet        bool                `json:",omitempty"`
 	NetfilterKindSet          bool                `json:",omitempty"`
+	RemoteConfigSet           bool                `json:",omitempty"`
 }
 
 type AutoUpdatePrefsMask struct {
@@ -467,6 +472,9 @@ func (p *Prefs) pretty(goos string) string {
 	if p.ShieldsUp {
 		sb.WriteString("shields=true ")
 	}
+	if p.RemoteConfig {
+		sb.WriteString("remoteconfig=true ")
+	}
 	if p.ExitNodeIP.IsValid() {
 		fmt.Fprintf(&sb, "exit=%v lan=%t ", p.ExitNodeIP, p.ExitNodeAllowLANAccess)
 	} else if !p.ExitNodeID.IsZero() {
@@ -549,6 +557,7 @@ func (p *Prefs) Equals(p2 *Prefs) bool {
 		p.OperatorUser == p2.OperatorUser &&
 		p.Hostname == p2.Hostname &&
 		p.ForceDaemon == p2.ForceDaemon &&
+		p.RemoteConfig == p2.RemoteConfig &&
 		compareIPNets(p.AdvertiseRoutes, p2.AdvertiseRoutes) &&
 		compareStrings(p.AdvertiseTags, p2.AdvertiseTags) &&
 		p.Persist.Equals(p2.Persist) &&
diff --git a/ipn/prefs_test.go b/ipn/prefs_test.go
index 9251bb2bb..acb7b0feb 100644
--- a/ipn/prefs_test.go
+++ b/ipn/prefs_test.go
@@ -62,6 +62,7 @@ func TestPrefsEqual(t *testing.T) {
 		"AppConnector",
 		"PostureChecking",
 		"NetfilterKind",
+		"RemoteConfig",
 		"Persist",
 	}
 	if have := fieldsOf(reflect.TypeFor[Prefs]()); !reflect.DeepEqual(have, prefsHandles) {
@@ -436,6 +437,11 @@ func TestPrefsPretty(t *testing.T) {
 			"Prefs{ra=false mesh=false dns=false want=false shields=true update=off Persist=nil}",
 		},
 		{
+			Prefs{RemoteConfig: true},
+			"windows",
+			"Prefs{ra=false mesh=false dns=false want=false remoteconfig=true update=off Persist=nil}",
+		},
+		{
 			Prefs{AllowSingleHosts: true},
 			"windows",
 			"Prefs{ra=false dns=false want=false update=off Persist=nil}",
diff --git a/tailcfg/tailcfg.go b/tailcfg/tailcfg.go
index aeb41ce7e..42353e8ef 100644
--- a/tailcfg/tailcfg.go
+++ b/tailcfg/tailcfg.go
@@ -129,7 +129,8 @@ type CapabilityVersion int
 //   - 86: 2024-01-23: Client understands NodeAttrProbeUDPLifetime
 //   - 87: 2024-02-11: UserProfile.Groups removed (added in 66)
 //   - 88: 2024-03-05: Client understands NodeAttrSuggestExitNode
-const CurrentCapabilityVersion CapabilityVersion = 88
+//   - 89: 2024-03-07: c2n remote config prefs
+const CurrentCapabilityVersion CapabilityVersion = 89
 
 type StableID string