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ipn, ipn/ipnlocal: reduce coupling between LocalBackend/profileManager and the Windows-specific "current user" model

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Ultimately, we'd like to get rid of the concept of the "current user". It is only used on Windows,
but even then it doesn't work well in multi-user and enterprise/managed Windows environments.

In this PR, we update LocalBackend and profileManager to decouple them a bit more from this obsolete concept.
This is done in a preparation for extracting ipnlocal.Extension-related interfaces and types, and using them
to implement optional features like tailscale/corp#27645, instead of continuing growing the core ipnlocal logic.

Notably, we rename (*profileManager).SetCurrentUserAndProfile() to SwitchToProfile() and change its signature
to accept an ipn.LoginProfileView instead of an ipn.ProfileID and ipn.WindowsUserID. Since we're not removing
the "current user" completely just yet, the method sets the current user to the owner of the target profile.

We also update the profileResolver callback type, which is typically implemented by LocalBackend extensions,
to return an ipn.LoginProfileView instead of ipn.ProfileID and ipn.WindowsUserID.

Updates tailscale/corp#27645
Updates tailscale/corp#18342

Signed-off-by: Nick Khyl <nickk@tailscale.com>
This commit is contained in:
Nick Khyl
2025-04-05 22:15:26 -05:00
committed by Nick Khyl
parent 476a4c6ff1
commit 94f4f83731
6 changed files with 207 additions and 166 deletions
Download Patch File Download Diff File Expand all files Collapse all files
ipn/ipnlocal/local.go
+45 -42
View File
@@ -204,13 +204,12 @@ func RegisterExtension(name string, newExt NewExtensionFn) {
mak.Set(&registeredExtensions, name, newExt)
}
// profileResolver is any function that returns user and profile IDs
// along with a flag indicating whether it succeeded. Since an empty
// profile ID ("") represents an empty profile, the ok return parameter
// distinguishes between an empty profile and no profile.
// profileResolver is any function that returns a read-only view of a login profile.
// An invalid view indicates no profile. A valid profile view with an empty [ipn.ProfileID]
// indicates that the profile is new and has not been persisted yet.
//
// It is called with [LocalBackend.mu] held.
type profileResolver func() (_ ipn.WindowsUserID, _ ipn.ProfileID, ok bool)
type profileResolver func() ipn.LoginProfileView
// NewControlClientCallback is a function to be called when a new [controlclient.Client]
// is created and before it is first used. The login profile and prefs represent
@@ -4006,13 +4005,21 @@ func (b *LocalBackend) SwitchToBestProfile(reason string) {
func (b *LocalBackend) switchToBestProfileLockedOnEntry(reason string, unlock unlockOnce) {
defer unlock()
oldControlURL := b.pm.CurrentPrefs().ControlURLOrDefault()
uid, profileID, background := b.resolveBestProfileLocked()
cp, switched := b.pm.SetCurrentUserAndProfile(uid, profileID)
profile, background := b.resolveBestProfileLocked()
cp, switched, err := b.pm.SwitchToProfile(profile)
switch {
case !switched && cp.ID() == "":
b.logf("%s: staying on empty profile", reason)
if err != nil {
b.logf("%s: an error occurred; staying on empty profile: %v", reason, err)
} else {
b.logf("%s: staying on empty profile", reason)
}
case !switched:
b.logf("%s: staying on profile %q (%s)", reason, cp.UserProfile().LoginName, cp.ID())
if err != nil {
b.logf("%s: an error occurred; staying on profile %q (%s): %v", reason, cp.UserProfile().LoginName, cp.ID(), err)
} else {
b.logf("%s: staying on profile %q (%s)", reason, cp.UserProfile().LoginName, cp.ID())
}
case cp.ID() == "":
b.logf("%s: disconnecting Tailscale", reason)
case background:
@@ -4032,7 +4039,7 @@ func (b *LocalBackend) switchToBestProfileLockedOnEntry(reason string, unlock un
// the TKA initialization or [LocalBackend.Start] can fail.
// These errors are not critical as far as we're concerned.
// But maybe we should post a notification to the API watchers?
b.logf("failed switching profile to %q: %v", profileID, err)
b.logf("failed switching profile to %q: %v", profile.ID(), err)
}
}
@@ -4041,30 +4048,29 @@ func (b *LocalBackend) switchToBestProfileLockedOnEntry(reason string, unlock un
// the unattended mode is enabled, the current state of the desktop sessions,
// and other factors.
//
// It returns the user ID, profile ID, and whether the returned profile is
// considered a background profile. A background profile is used when no OS user
// is actively using Tailscale, such as when no GUI/CLI client is connected
// and Unattended Mode is enabled (see also [LocalBackend.getBackgroundProfileLocked]).
// An empty profile ID indicates that Tailscale should switch to an empty profile.
// It returns a read-only view of the profile and whether it is considered
// a background profile. A background profile is used when no OS user is actively
// using Tailscale, such as when no GUI/CLI client is connected and Unattended Mode
// is enabled (see also [LocalBackend.getBackgroundProfileLocked]).
//
// An invalid view indicates no profile, meaning Tailscale should disconnect
// and remain idle until a GUI or CLI client connects.
// A valid profile view with an empty [ipn.ProfileID] indicates a new profile that
// has not been persisted yet.
//
// b.mu must be held.
func (b *LocalBackend) resolveBestProfileLocked() (userID ipn.WindowsUserID, profileID ipn.ProfileID, isBackground bool) {
func (b *LocalBackend) resolveBestProfileLocked() (_ ipn.LoginProfileView, isBackground bool) {
// If a GUI/CLI client is connected, use the connected user's profile, which means
// either the current profile if owned by the user, or their default profile.
if b.currentUser != nil {
cp := b.pm.CurrentProfile()
uid := b.currentUser.UserID()
var profileID ipn.ProfileID
profile := b.pm.CurrentProfile()
// TODO(nickkhyl): check if the current profile is allowed on the device,
// such as when [syspolicy.Tailnet] policy setting requires a specific Tailnet.
// See tailscale/corp#26249.
if cp.LocalUserID() == uid {
profileID = cp.ID()
} else {
profileID = b.pm.DefaultUserProfileID(uid)
if uid := b.currentUser.UserID(); profile.LocalUserID() != uid {
profile = b.pm.DefaultUserProfile(uid)
}
return uid, profileID, false
return profile, false
}
// Otherwise, if on Windows, use the background profile if one is set.
@@ -4073,8 +4079,8 @@ func (b *LocalBackend) resolveBestProfileLocked() (userID ipn.WindowsUserID, pro
// If the returned background profileID is "", Tailscale will disconnect
// and remain idle until a GUI or CLI client connects.
if goos := envknob.GOOS(); goos == "windows" {
uid, profileID := b.getBackgroundProfileLocked()
return uid, profileID, true
profile := b.getBackgroundProfileLocked()
return profile, true
}
// On other platforms, however, Tailscale continues to run in the background
@@ -4083,7 +4089,7 @@ func (b *LocalBackend) resolveBestProfileLocked() (userID ipn.WindowsUserID, pro
// TODO(nickkhyl): check if the current profile is allowed on the device,
// such as when [syspolicy.Tailnet] policy setting requires a specific Tailnet.
// See tailscale/corp#26249.
return b.pm.CurrentUserID(), b.pm.CurrentProfile().ID(), false
return b.pm.CurrentProfile(), false
}
// RegisterBackgroundProfileResolver registers a function to be used when
@@ -4100,30 +4106,31 @@ func (b *LocalBackend) RegisterBackgroundProfileResolver(resolver profileResolve
}
}
// getBackgroundProfileLocked returns the user and profile ID to use when no GUI/CLI
// client is connected, or "","" if Tailscale should not run in the background.
// getBackgroundProfileLocked returns a read-only view of the profile to use
// when no GUI/CLI client is connected. If Tailscale should not run in the background
// and should disconnect until a GUI/CLI client connects, the returned view is not valid.
// As of 2025-02-07, it is only used on Windows.
func (b *LocalBackend) getBackgroundProfileLocked() (ipn.WindowsUserID, ipn.ProfileID) {
func (b *LocalBackend) getBackgroundProfileLocked() ipn.LoginProfileView {
// TODO(nickkhyl): check if the returned profile is allowed on the device,
// such as when [syspolicy.Tailnet] policy setting requires a specific Tailnet.
// See tailscale/corp#26249.
// If Unattended Mode is enabled for the current profile, keep using it.
if b.pm.CurrentPrefs().ForceDaemon() {
return b.pm.CurrentProfile().LocalUserID(), b.pm.CurrentProfile().ID()
return b.pm.CurrentProfile()
}
// Otherwise, attempt to resolve the background profile using the background
// profile resolvers available on the current platform.
for _, resolver := range b.backgroundProfileResolvers {
if uid, profileID, ok := resolver(); ok {
return uid, profileID
if profile := resolver(); profile.Valid() {
return profile
}
}
// Otherwise, switch to an empty profile and disconnect Tailscale
// until a GUI or CLI client connects.
return "", ""
return ipn.LoginProfileView{}
}
// CurrentUserForTest returns the current user and the associated WindowsUserID.
@@ -7555,13 +7562,9 @@ func (b *LocalBackend) SwitchProfile(profile ipn.ProfileID) error {
unlock := b.lockAndGetUnlock()
defer unlock()
if b.pm.CurrentProfile().ID() == profile {
return nil
}
oldControlURL := b.pm.CurrentPrefs().ControlURLOrDefault()
if err := b.pm.SwitchProfile(profile); err != nil {
return err
if _, changed, err := b.pm.SwitchToProfileByID(profile); !changed || err != nil {
return err // nil if we're already on the target profile
}
// As an optimization, only reset the dialPlan if the control URL changed.
@@ -7750,7 +7753,7 @@ func (b *LocalBackend) NewProfile() error {
unlock := b.lockAndGetUnlock()
defer unlock()
b.pm.NewProfile()
b.pm.SwitchToNewProfile()
// The new profile doesn't yet have a ControlURL because it hasn't been
// set. Conservatively reset the dialPlan.