In this PR, we enable the registration of LocalBackend extensions to exclude code specific to certain
platforms or environments. We then introduce desktopSessionsExt, which is included only in Windows builds
and only if the ts_omit_desktop_sessions tag is disabled for the build. This extension tracks desktop sessions
and switches to (or remains on) the appropriate profile when a user signs in or out, locks their screen,
or disconnects a remote session.
As desktopSessionsExt requires an ipn/desktop.SessionManager, we register it with tsd.System
for the tailscaled subprocess on Windows.
We also fix a bug in the sessionWatcher implementation where it attempts to close a nil channel on stop.
Updates #14823
Updates tailscale/corp#26247
Signed-off-by: Nick Khyl <nickk@tailscale.com>
In this PR, we further refactor LocalBackend and Unattended Mode to extract the logic that determines
which profile should be used at the time of the check, such as when a LocalAPI client connects or disconnects.
We then update (*LocalBackend).switchProfileLockedOnEntry to to switch to the profile returned by
(*LocalBackend).resolveBestProfileLocked() rather than to the caller-specified specified profile, and rename it
to switchToBestProfileLockedOnEntry.
This is done in preparation for updating (*LocalBackend).getBackgroundProfileIDLocked to support Always-On
mode by determining which profile to use based on which users, if any, are currently logged in and have an active
foreground desktop session.
Updates #14823
Updates tailscale/corp#26247
Signed-off-by: Nick Khyl <nickk@tailscale.com>
Currently, we disconnect Tailscale and reset LocalBackend on Windows when the last LocalAPI client
disconnects, unless Unattended Mode is enabled for the current profile. And the implementation
is somewhat racy since the current profile could theoretically change after
(*ipnserver.Server).addActiveHTTPRequest checks (*LocalBackend).InServerMode() and before it calls
(*LocalBackend).SetCurrentUser(nil) (or, previously, (*LocalBackend).ResetForClientDisconnect).
Additionally, we might want to keep Tailscale running and connected while a user is logged in
rather than tying it to whether a LocalAPI client is connected (i.e., while the GUI is running),
even when Unattended Mode is disabled for a profile. This includes scenarios where the new
AlwaysOn mode is enabled, as well as when Tailscale is used on headless Windows editions,
such as Windows Server Core, where the GUI is not supported. It may also be desirable to switch
to the "background" profile when a user logs off from their device or implement other similar
features.
To facilitate these improvements, we move the logic from ipnserver.Server to ipnlocal.LocalBackend,
where it determines whether to keep Tailscale running when the current user disconnects.
We also update the logic that determines whether a connection should be allowed to better reflect
the fact that, currently, LocalAPI connections are not allowed unless:
- the current UID is "", meaning that either we are not on a multi-user system or Tailscale is idle;
- the LocalAPI client belongs to the current user (their UIDs are the same);
- the LocalAPI client is Local System (special case; Local System is always allowed).
Whether Unattended Mode is enabled only affects the error message returned to the Local API client
when the connection is denied.
Updates #14823
Signed-off-by: Nick Khyl <nickk@tailscale.com>
The context carries additional information about the actor, such as the
request reason, and is canceled when the actor is done.
Additionally, we implement three new ipn.Actor types that wrap other actors
to modify their behavior:
- WithRequestReason, which adds a request reason to the actor;
- WithoutClose, which narrows the actor's interface to prevent it from being
closed;
- WithPolicyChecks, which adds policy checks to the actor's CheckProfileAccess
method.
Updates #14823
Signed-off-by: Nick Khyl <nickk@tailscale.com>
There’s (*LocalBackend).ResetForClientDisconnect, and there’s also (*LocalBackend).resetForProfileChangeLockedOnEntry.
Both methods essentially did the same thing but in slightly different ways. For example, resetForProfileChangeLockedOnEntry didn’t reset the control client until (*LocalBackend).Start() was called at the very end and didn’t reset the keyExpired flag, while ResetForClientDisconnect didn’t reinitialize TKA.
Since SetCurrentUser can be called with a nil argument to reset the currently connected user and internally calls resetForProfileChangeLockedOnEntry, we can remove ResetForClientDisconnect and let SetCurrentUser and resetForProfileChangeLockedOnEntry handle it.
Updates #14823
Signed-off-by: Nick Khyl <nickk@tailscale.com>
updates tailscale/corp#25687
The darwin appstore and standalone clients now support XPC and the keychain for passing user credentials securely between the gui process and an NEVPNExtension hosted tailscaled. Clients that can communicate directly with the network extension, via XPC or the keychain, are now expected to call SetCredentials and supply credentials explicitly, fixing issues with the cli breaking if the current user cannot read the contents of /Library/Tailscale due to group membership restrictions. This matches how those clients source and supply credentials to the localAPI http client.
Non-platform-specific code that has traditionally been in the client is moved to safesocket.
/Libraray/Tailscaled/sameuserproof has its permissions changed to that it's readably only by users in the admin group. This restricts standalone CLI access for and direct use of localAPI to admins.
Signed-off-by: Jonathan Nobels <jonathan@tailscale.com>
It was moved in f57fa3cbc30e.
Updates tailscale/corp#22748
Change-Id: I19f965e6bded1d4c919310aa5b864f2de0cd6220
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
With #14843 merged, (*localapi.Handler).servePrefs() now requires a non-nil actor,
and other places may soon require it as well.
In this PR, we update localapi.NewHandler with a new required parameter for the actor.
We then update tsnet to use ipnauth.Self.
We also rearrange the code in (*ipnserver.Server).serveHTTP() to pass the actor via Handler's
constructor instead of the field.
Updates #14823
Signed-off-by: Nick Khyl <nickk@tailscale.com>
In this PR, we move the code that checks the AlwaysOn policy from ipnserver.actor to ipnauth.
It is intended to be used by ipnauth.Actor implementations, and we temporarily make it exported
while these implementations reside in ipnserver and in corp. We'll unexport it later.
We also update [ipnauth.Actor.CheckProfileAccess] to accept an auditLogger, which is called
to write details about the action to the audit log when required by the policy, and update
LocalBackend.EditPrefsAs to use an auditLogger that writes to the regular backend log.
Updates tailscale/corp#26146
Signed-off-by: Nick Khyl <nickk@tailscale.com>
In this PR, we update client/tailscale.LocalClient to allow sending requests with an optional X-Tailscale-Reason
header. We then update ipn/ipnserver.{actor,Server} to retrieve this reason, if specified, and use it to determine
whether ipnauth.Disconnect is allowed when the AlwaysOn.OverrideWithReason policy setting is enabled.
For now, we log the reason, along with the profile and OS username, to the backend log.
Finally, we update LocalBackend to remember when a disconnect was permitted and do not reconnect automatically
unless the policy changes.
Updates tailscale/corp#26146
Signed-off-by: Nick Khyl <nickk@tailscale.com>
In this PR, we update LocalBackend to set WantRunning=true when applying policy settings
to the current profile's prefs, if the "always-on" mode is enabled.
We also implement a new (*LocalBackend).EditPrefsAs() method, which is like EditPrefs
but accepts an actor (e.g., a LocalAPI client's identity) that initiated the change.
If WantRunning is being set to false, the new EditPrefsAs method checks whether the actor
has ipnauth.Disconnect access to the profile and propagates an error if they do not.
Finally, we update (*ipnserver.actor).CheckProfileAccess to allow a disconnect
only if the "always-on" mode is not enabled by the AlwaysOn policy setting.
This is not a comprehensive solution to the "always-on" mode across platforms,
as instead of disconnecting a user could achieve the same effect by creating
a new empty profile, initiating a reauth, or by deleting the profile.
These are the things we should address in future PRs.
Updates #14823
Signed-off-by: Nick Khyl <nickk@tailscale.com>
The implementations define it to verify whether the actor has the requested access to a login profile.
Updates #14823
Signed-off-by: Nick Khyl <nickk@tailscale.com>
If the server was in use at the time of the initial check, but disconnected and was removed
from the activeReqs map by the time we registered a waiter, the ready channel will never
be closed, resulting in a deadlock. To avoid this, we check whether the server is still busy
after registering the wait.
Fixes#14655
Signed-off-by: Nick Khyl <nickk@tailscale.com>
I made a last-minute change in #14626 to split a single loop that created 1_000 concurrent
connections into an inner and outer loop that create 100 concurrent connections 10 times.
This introduced a race because the last user's connection may still be active (from the server's
perspective) when a new outer iteration begins. Since every new client gets a unique ClientID,
but we reuse usernames and UIDs, the server may let a user in (as the UID matches, which is fine),
but the test might then fail due to a ClientID mismatch:
server_test.go:232: CurrentUser(Initial): got &{S-1-5-21-1-0-0-1001 User-4 <nil> Client-2 false false};
want &{S-1-5-21-1-0-0-1001 User-4 <nil> Client-114 false false}
In this PR, we update (*testIPNServer).blockWhileInUse to check whether the server is currently busy
and wait until it frees up. We then call blockWhileInUse at the end of each outer iteration so that the server
is always in a known idle state at the beginning of the inner loop. We also check that the current user
is not set when the server is idle.
Updates tailscale/corp#25804
Updates #14655 (found when working on it)
Signed-off-by: Nick Khyl <nickk@tailscale.com>
In this commit, we add a failing test to verify that ipn/ipnserver.Server correctly
sets and unsets the current user when two different clients send requests concurrently
(A sends request, B sends request, A's request completes, B's request completes).
The expectation is that the user who wins the race becomes the current user
from the LocalBackend's perspective, remaining in this state until they disconnect,
after which a different user should be able to connect and use the LocalBackend.
We then fix the second of two bugs in (*Server).addActiveHTTPRequest, where a race
condition causes the LocalBackend's state to be reset after a new client connects,
instead of after the last active request of the previous client completes and the server
becomes idle.
Fixestailscale/corp#25804
Signed-off-by: Nick Khyl <nickk@tailscale.com>
In this commit, we add a failing test to verify that ipn/ipnserver.Server correctly
sets and unsets the current user when two different users connect sequentially
(A connects, A disconnects, B connects, B disconnects).
We then fix the test by updating (*ipn/ipnserver.Server).addActiveHTTPRequest
to avoid calling (*LocalBackend).ResetForClientDisconnect again after a new user
has connected and been set as the current user with (*LocalBackend).SetCurrentUser().
Since ipn/ipnserver.Server does not allow simultaneous connections from different
Windows users and relies on the LocalBackend's current user, and since we already
reset the LocalBackend's state by calling ResetForClientDisconnect when the last
active request completes (indicating the server is idle and can accept connections
from any Windows user), it is unnecessary to track the last connected user on the
ipnserver.Server side or call ResetForClientDisconnect again when the user changes.
Additionally, the second call to ResetForClientDisconnect occurs after the new user
has been set as the current user, resetting the correct state for the new user
instead of the old state of the now-disconnected user, causing issues.
Updates tailscale/corp#25804
Signed-off-by: Nick Khyl <nickk@tailscale.com>
We update client/tailscale.LocalClient to allow specifying an optional Transport
(http.RoundTripper) for LocalAPI HTTP requests, and implement one that injects
an ipnauth.TestActor via request headers. We also add several functions and types
to make testing an ipn/ipnserver.Server possible (or at least easier).
We then use these updates to write basic tests for ipnserver.Server,
ensuring it works on non-Windows platforms and correctly sets and unsets
the LocalBackend's current user when a Windows user connects and disconnects.
We intentionally omit tests for switching between different OS users
and will add them in follow-up commits.
Updates tailscale/corp#25804
Signed-off-by: Nick Khyl <nickk@tailscale.com>
In preparation for adding test coverage for ipn/ipnserver.Server, we update it
to use ipnauth.Actor instead of its concrete implementation where possible.
Updates tailscale/corp#25804
Signed-off-by: Nick Khyl <nickk@tailscale.com>
We add the ClientID() method to the ipnauth.Actor interface and updated ipnserver.actor to implement it.
This method returns a unique ID of the connected client if the actor represents one. It helps link a series
of interactions initiated by the client, such as when a notification needs to be sent back to a specific session,
rather than all active sessions, in response to a certain request.
We also add LocalBackend.WatchNotificationsAs and LocalBackend.StartLoginInteractiveAs methods,
which are like WatchNotifications and StartLoginInteractive but accept an additional parameter
specifying an ipnauth.Actor who initiates the operation. We store these actor identities in
watchSession.owner and LocalBackend.authActor, respectively,and implement LocalBackend.sendTo
and related helper methods to enable sending notifications to watchSessions associated with actors
(or, more broadly, identifiable recipients).
We then use the above to change who receives the BrowseToURL notifications:
- For user-initiated, interactive logins, the notification is delivered only to the user who initiated the
process. If the initiating actor represents a specific connected client, the URL notification is sent back
to the same LocalAPI client that called StartLoginInteractive. Otherwise, the notification is sent to all
clients connected as that user.
Currently, we only differentiate between users on Windows, as it is inherently a multi-user OS.
- In all other cases (e.g., node key expiration), we send the notification to all connected users.
Updates tailscale/corp#18342
Signed-off-by: Nick Khyl <nickk@tailscale.com>
We no longer need this on Windows, and it was never required on other platforms.
It just results in more short-lived connections unless we use HTTP/2.
Updates tailscale/corp#18342
Signed-off-by: Nick Khyl <nickk@tailscale.com>
Currently, we use PermitRead/PermitWrite/PermitCert permission flags to determine which operations are allowed for a LocalAPI client.
These checks are performed when localapi.Handler handles a request. Additionally, certain operations (e.g., changing the serve config)
requires the connected user to be a local admin. This approach is inherently racey and is subject to TOCTOU issues.
We consider it to be more critical on Windows environments, which are inherently multi-user, and therefore we prevent more than one
OS user from connecting and utilizing the LocalBackend at the same time. However, the same type of issues is also applicable to other
platforms when switching between profiles that have different OperatorUser values in ipn.Prefs.
We'd like to allow more than one Windows user to connect, but limit what they can see and do based on their access rights on the device
(e.g., an local admin or not) and to the currently active LoginProfile (e.g., owner/operator or not), while preventing TOCTOU issues on Windows
and other platforms. Therefore, we'd like to pass an actor from the LocalAPI to the LocalBackend to represent the user performing the operation.
The LocalBackend, or the profileManager down the line, will then check the actor's access rights to perform a given operation on the device
and against the current (and/or the target) profile.
This PR does not change the current permission model in any way, but it introduces the concept of an actor and includes some preparatory
work to pass it around. Temporarily, the ipnauth.Actor interface has methods like IsLocalSystem and IsLocalAdmin, which are only relevant
to the current permission model. It also lacks methods that will actually be used in the new model. We'll be adding these gradually in the next
PRs and removing the deprecated methods and the Permit* flags at the end of the transition.
Updates tailscale/corp#18342
Signed-off-by: Nick Khyl <nickk@tailscale.com>
There was a small window in ipnserver after we assigned a LocalBackend
to the ipnserver's atomic but before we Start'ed it where our
initalization Start could conflict with API calls from the LocalAPI.
Simplify that a bit and lay out the rules in the docs.
Updates #12028
Change-Id: Ic5f5e4861e26340599184e20e308e709edec68b1
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
When establishing connections to the ipnserver, we validate that the
local user is allowed to connect. If Tailscale is currently being
managed by a different user (primarily for multi-user Windows installs),
we don't allow the connection.
With the new device web UI, the inbound connection is coming from
tailscaled itself, which is often running as "NT AUTHORITY\SYSTEM".
In this case, we still want to allow the connection, even though it
doesn't match the user running the Tailscale GUI. The SYSTEM user has
full access to everything on the system anyway, so this doesn't escalate
privileges.
Eventually, we want the device web UI to run outside of the tailscaled
process, at which point this exception would probably not be needed.
Updates tailscale/corp#16393
Signed-off-by: Will Norris <will@tailscale.com>
On unix systems, the check involves executing sudo, which is slow.
Instead of doing it for every incoming request, move the logic into
localapi serveServeConfig handler and do it as needed.
Updates tailscale/corp#15405
Signed-off-by: Andrew Lytvynov <awly@tailscale.com>
For an operator user, require them to be able to `sudo tailscale` to use
`tailscale serve`. This is similar to the Windows elevated token check.
Updates tailscale/corp#15405
Signed-off-by: Andrew Lytvynov <awly@tailscale.com>
(*Token).IsAdministrator is supposed to return true even when the user is
running with a UAC limited token. The idea is that, for the purposes of
this check, we don't care whether the user is *currently* running with
full Admin rights, we just want to know whether the user can
*potentially* do so.
We accomplish this by querying for the token's "linked token," which
should be the fully-elevated variant, and checking its group memberships.
We also switch ipn/ipnserver/(*Server).connIsLocalAdmin to use the elevation
check to preserve those semantics for tailscale serve; I want the
IsAdministrator check to be used for less sensitive things like toggling
auto-update on and off.
Fixes#10036
Signed-off-by: Aaron Klotz <aaron@tailscale.com>
On Windows, the idiomatic way to check access on a named pipe is for
the server to impersonate the client on its current OS thread, perform
access checks using the client's access token, and then revert the OS
thread's access token back to its true self.
The access token is a better representation of the client's rights than just
a username/userid check, as it represents the client's effective rights
at connection time, which might differ from their normal rights.
This patch updates safesocket to do the aforementioned impersonation,
extract the token handle, and then revert the impersonation. We retain
the token handle for the remaining duration of the connection (the token
continues to be valid even after we have reverted back to self).
Since the token is a property of the connection, I changed ipnauth to wrap
the concrete net.Conn to include the token. I then plumbed that change
through ipnlocal, ipnserver, and localapi as necessary.
I also added a PermitLocalAdmin flag to the localapi Handler which I intend
to use for controlling access to a few new localapi endpoints intended
for configuring auto-update.
Updates https://github.com/tailscale/tailscale/issues/755
Signed-off-by: Aaron Klotz <aaron@tailscale.com>
This allows sending logs from the "logpolicy" package (and associated
callees) to something other than the log package. The behaviour for
tailscaled remains the same, passing in log.Printf
Updates #8249
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ie1d43b75fa7281933d9225bffd388462c08a5f31
This is part of an effort to clean up tailscaled initialization between
tailscaled, tailscaled Windows service, tsnet, and the mac GUI.
Updates #8036
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
On some platforms (notably macOS and iOS) we look up the default
interface to bind outgoing connections to. This is both duplicated
work and results in logspam when the default interface is not available
(i.e. when a phone has no connectivity, we log an error and thus cause
more things that we will try to upload and fail).
Fixed by passing around a netmon.Monitor to more places, so that we can
use its cached interface state.
Fixes#7850
Updates #7621
Signed-off-by: Mihai Parparita <mihai@tailscale.com>
This change focuses on the backend log ID, which is the mostly commonly
used in the client. Tests which don't seem to make use of the log ID
just use the zero value.
Signed-off-by: Will Norris <will@tailscale.com>
This updates all source files to use a new standard header for copyright
and license declaration. Notably, copyright no longer includes a date,
and we now use the standard SPDX-License-Identifier header.
This commit was done almost entirely mechanically with perl, and then
some minimal manual fixes.
Updates #6865
Signed-off-by: Will Norris <will@tailscale.com>
This ensures that we capture error returned by `Serve` and exit with a
non-zero exit code if it happens.
Signed-off-by: Anton Tolchanov <anton@tailscale.com>
tailscaled on Windows had two entirely separate start-up paths for running
as a service vs in the foreground. It's been causing problems for ages.
This unifies the two paths, making them be the same as the path used
for every other platform.
Also, it uses the new async LocalBackend support in ipnserver.Server
so the Server can start serving HTTP immediately, even if tun takes
awhile to come up.
Updates #6535
Change-Id: Icc8c4f96d4887b54a024d7ac15ad11096b5a58cf
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This is step 1 of de-special-casing of Windows and letting the
LocalAPI HTTP server start serving immediately, even while the rest of
the world (notably the Engine and its TUN device) are being created,
which can take a few to dozens of seconds on Windows.
With this change, the ipnserver.New function changes to not take an
Engine and to return immediately, not returning an error, and let its
Run run immediately. If its ServeHTTP is called when it doesn't yet
have a LocalBackend, it returns an error. A TODO in there shows where
a future handler will serve status before an engine is available.
Future changes will:
* delete a bunch of tailscaled_windows.go code and use this new API
* add the ipnserver.Server ServerHTTP handler to await the engine
being available
* use that handler in the Windows GUI client
Updates #6522
Change-Id: Iae94e68c235e850b112a72ea24ad0e0959b568ee
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
The "userID is empty everywhere but Windows" docs on lots of places
but not everywhere while using just a string type was getting
confusing. This makes a new type to wrap up those rules, however
weird/historical they might be.
Change-Id: I142e85a8e38760988d6c0c91d0efecedade81b9b
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
We'll eventually remove it entirely, but for now move get it out of ipnserver
where it's distracting and move it to its sole caller.
Updates #6522
Change-Id: I9c6f6a91bf9a8e3c5ea997952b7c08c81723d447
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Now that everything's just HTTP, there's no longer a need to have a
header-sniffing net.Conn wraper that dispatches which route to
take. Refactor to just use an http.Server earlier instead.
Updates #6417
Change-Id: I12a2054db4e56f48660c46f81233db224fdc77cb
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
It's only used by Windows. No need for it to be in ipn/ipnserver,
which we're trying to trim down.
Change-Id: Idf923ac8b6cdae8b5338ec26c16fb8b5ea548071
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Unused in this repo as of the earlier #6450 (300aba61a6)
and unused in the Windows GUI as of tailscale/corp#8065.
With this ipn.BackendServer is no longer used and could also be
removed from this repo. The macOS and iOS clients still temporarily
depend on it, but I can move it to that repo instead while and let its
migration proceed on its own schedule while we clean this repo up.
Updates #6417
Updates tailscale/corp#8051
Change-Id: Ie13f82af3eb9f96b3a21c56cdda51be31ddebdcf
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Follow-up to #6467 and #6506.
LocalBackend knows the server-mode state, so move more auth checking
there, removing some bookkeeping from ipnserver.Server.
Updates #6417
Updates tailscale/corp#8051
Change-Id: Ic5d14a077bf0dccc92a3621bd2646bab2cc5b837
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
