Commit Graph
248 Commits
Author SHA1 Message Date
Brad Fitzpatrick 664ba588ab ssh/tailssh: split the OS-specific parts of the server into their own files
The main server file mixed portable session handling with Unix details:
sending SIGHUP to end a session, decoding exec.ExitError, the euid check
for whether the process can switch users, agent forwarding's chown of the
socket, and reading /etc/ssh host keys as root. Those now sit behind small
functions (hangupProcess, waitProcess, canSwitchToLocalUser,
handleSSHAgentForwarding, systemHostKeyFile, isRootUser) in the new
process_unix.go, along with the incubator's forwarded-environment pipe
helpers, and the session's *exec.Cmd moves into an embedded osSessionState
struct defined there, so that the portable code no longer refers to the
process representation at all.

user.go keeps only the portable userMeta and userLookup; the login shell
and default PATH logic moves to user_unix.go. The SFTP child entrypoint and
its stdio adapter, which incubator.go and incubator_plan9.go each had a
copy of, move to sftp.go. The c2n usernames handler gains a hook for
platforms that list users some other way than /etc/passwd.

The agent socket's uid and gid are parsed as 31-bit rather than 32-bit
unsigned values so that the conversion to int for os.Chown cannot
overflow on 32-bit platforms, which is the pattern CodeQL flags.

Updates #cleanup

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Change-Id: I4c7e2b9a0d3f5e1c8b6a4d2f0e9c7b5a3d1f8e6c
2026-09-15 19:32:40 -07:00
Brad Fitzpatrick 2ee809d10d feature: add TS_DISABLE_FEATURE to disable features at runtime
The ts_omit_<name> build tags omit a feature at build time; there has
been no way to do the same at runtime. Some users (either proactively
or in response to a security announcement) might like a way to disable
a feature that's linked-in in their binaries that they're not using.
Then a mitigation announcement can say "set this env var" without
asking users to rebuild or wait for a new release.

This adds env var TS_DISABLE_FEATURE, a comma-separated list of
feature names to disable, and the listed set is reported by the
debug-optional-features LocalAPI endpoint next to the registered set.
The legacy per-feature knobs such as TS_DISABLE_SSH_SERVER and
TS_DISABLE_TAILDROP keep working independently.

A disabled feature behaves as if it had not been linked: it is absent
from feature.IsRegistered, its hooks are unset, and its extensions and
handlers are not registered. Three pieces make that happen:

  * feature.Register now returns bool, false when disabled, and
    feature packages gate their registration init on it. It was added
    to the feature packages that never called it (including taildrop
    and ssh), which also completes the picture reported by
    debug-optional-features. taildrop, routecheck, favorites, and
    serviceclientprefs had registration split across several inits and
    now register from one gated init.
  * ipnext.RegisterExtension ignores a disabled feature's extension.
  * feature.Hook.Set and feature.Hooks.Add walk the call stack and
    silently skip when the calling package under feature/<name> is
    disabled. This covers sub-packages such as
    feature/captiveportal/netcheckhook, which cannot call Register
    themselves without colliding with their parent, and future
    packages whose authors forget the gate.

ssh/tailssh's registrations moved from its inits into tailssh.Register,
called from feature/ssh's gated init. The aws and kube state stores and
syspolicy's Windows store registration are gated too.

feature/register_disable_test.go runs this test binary as a child
process (it links condregister, as tailscaled does) with
TS_DISABLE_FEATURE set to every registered feature at once, and fails
if any of them register anyway, so a feature that ignores the variable
cannot land.

Updates #12614

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Change-Id: I720af6ccab844ae060a9dfd1539fee577fd483e3
2026-09-15 08:37:47 -07:00
Simon Law 00699abdfb tailcfg,tailcfg/{nodecap,selfcap}: split capability constants to their own packages (#20639)
Package tailcfg defines the types and constants used by the Tailscale
protocol, but since everything is all in one package, it’s difficult
to sift through the docs: https://pkg.go.dev/tailscale.com/tailcfg

We define and enumerate capabilities as string constants for
tailcfg.NodeCapability and tailcfg.PeerCapability. This PR extracts
them into their own packages:

- tailcfg.CapabilityFileSharing becomes nodecap.FileSharing
- tailcfg.NodeAttrOnlyTCP443 becomes nodecap.OnlyTCP443
- tailcfg.PeerCapabilityTaildrive becomes peercap.Taildrive

We originally intended for CapabilityFoo to grant an entitlement or
permission for Foo, and for NodeAttrBar to configure Bar in the
nodeAttrs section of the policy file. However, there was no technical
enforcement of this convention, so new capabilities have used the
NodeAttr prefix regardless of meaning. Therefore, this PR unifies
tailcfg.CapabilityFoo and tailcfg.NodeAttrBar into a single package as
nodecap.Foo and nodecap.Bar.

Ran `go fix -inline ./...` and committed the changes that replaced
uses of the tailcfg aliases with the authoritative ones.

Updates #20259

Change-Id: Ieb7e7e6c8247c39faf42fdf15c68cdc7c621c730
Signed-off-by: Simon Law <sfllaw@tailscale.com>
2026-08-07 16:30:35 -07:00
Patrick O'DohertyandMike Jensen 9d48dbd561 ssh/tailssh: keep acceptEnv values and names out of the incubator cmdline (#20552)
Previously the acceptEnv variables forwarded to the incubator child were
JSON-encoded onto its command line (--encoded-env), so their values were
visible in /proc/<pid>/cmdline to any other local user and were logged in
the session-start argv (locally and to log.tailscale.com except where
--no-logs-no-support was specified).

This change now carries those variables through an os.Pipe file
descriptor as a json encoded payload. Added end-to-end testing
helps validate secrets reach the session but are not in flags or logged.

Fixes tailscale/corp#44903

Change-Id: I5b137b20e9c06feec6b70aaf4e6925e6db74017e

Signed-off-by: Mike Jensen <mikej@tailscale.com>
Co-authored-by: Mike Jensen <mikej@tailscale.com>
2026-07-30 09:57:55 -06:00
Kristoffer Dalby dd426dbb51 ssh/tailssh: hold CHANNEL_EOF until both output streams drain
The previous commit sent CHANNEL_EOF from the stdout copier as soon as
stdout hit EOF. With the process exited and the send window exhausted by
a slow client, the stderr copier could still be draining its backlog;
x/crypto/ssh fails every write after EOF (WriteExtended checks sentEOF),
so the tail of stderr was silently dropped.

Send CloseWrite from run() itself, after cmd.Wait, exit-status and both
output copiers have finished. Wire order is unchanged: exit-status,
remaining output, EOF, CHANNEL_CLOSE.

The test withholds stderr window credit until the process has exited
server-side, then releases it and checks the final bytes arrived. It
also pins the harness login shell to /bin/sh; fish forks -c commands and
stays resident, changing pipe fd ownership under test.

Updates #18256

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>
2026-07-30 10:18:00 +02:00
James Tucker 92f43003fc ssh/tailssh: fix exit-status frame ordering
Send exit-status before EOF before CHANNEL_CLOSE per RFC 4254 §6.10.
The old code raced CloseWrite against Exit; macOS OpenSSH often saw
EOF first and dropped the exit code.

Replace atomic.Bool/atomic.Int32/channel sync with a sync.WaitGroup
over the output goroutines and emit:

    cmd.Wait -> ss.Exit -> closeAll(childPipes) -> wg.Wait -> ss.Close

The stdin copier stays out of wg: it blocks reading from the SSH
channel until the client half-closes, and many clients (go-scp,
plain `ssh host cmd`, scp, sftp) don't half-close before they
receive CHANNEL_CLOSE from us. Including it deadlocks. It self-
cleans via deferred ss.Close.

Align exit codes with shell convention:
  255 SSH-internal error (OpenSSH ssh.c:1693)
  254 recording-infrastructure failure
  127 command-not-found (POSIX)

Switch session termination from SIGKILL to SIGHUP, matching
OpenSSH PTY-master-close (session.c:2246). Process-group delivery
follows in a later commit.

Relies on the gliderssh wire-order change (tailscale/gliderssh#8),
which go.mod already pins since 3f5eb3199.

Based on tailscale/tailscale#18331.

Updates #18256

Signed-off-by: James Tucker <james@tailscale.com>
Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>
2026-07-30 10:18:00 +02:00
Kristoffer Dalby 12fcb2217b ssh/tailssh: test exit-status frame ordering and stderr drain
Added before the fix so CI records the failure. Frame order is asserted
off the session interface rather than through a client, so it holds on
any GOOS instead of depending on how a particular client reacts.

Measured on CI against this commit, no fix yet:

  TestExitStatusPrecedesEOF   FAIL on darwin, linux/amd64 and the
        privileged linux job, 10/10 retries, classified permanent:
        got [eof exit-status], want [exit-status eof close]
  TestExitCodePassthrough     PASS on both
  TestStderrTailNotTruncated  PASS on both (guards a 2022 fix)

The ordering assertion is the only thing that pins this bug. Exit-code
assertions do not: OpenSSH 10.2p1 on darwin reads the pending
exit-status request after EOF just as linux does, so the wrong frame
order is invisible to the client's exit status over the direct-exec
path. The exit-status loss reported in #18256 comes from
/usr/bin/login -pq in the incubator path, which is a separate defect.

Updates #18256

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>
2026-07-30 10:18:00 +02:00
Kristoffer Dalby ea3f83216b ssh/tailssh: add exit-status test harness
Extract the in-process SSH server harness out of tailssh_test.go into
tailssh_exitcodes_test.go so the exit-status tests can share it, and add
the integrationtest-tagged exit-code suite (Go and OpenSSH clients).

Updates #18256

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>
2026-07-30 10:18:00 +02:00
Mario Minardi e48e7b730a ssh/tailssh: check if user matching autogroup:nonroot is root
Add a check to ensure that the user being matched to an
autogroup:nonroot rule is in fact a non-root user on the system.

Updates https://github.com/tailscale/corp/issues/43245

Signed-off-by: Mario Minardi <mario@tailscale.com>
2026-07-27 17:18:34 -06:00
Mario Minardi f368a96e01 ssh/tailssh: dissallow purely numeric usernames for SSH
Dissallow purely numeric usernames for SSH as these are ambiguous with
numeric UID values.

Updates https://github.com/tailscale/corp/issues/43245

Signed-off-by: Mario Minardi <mario@tailscale.com>
2026-06-11 17:52:51 -06:00
ferrumclaudepilgrim 3f70abdc6f cmd/tailscaled, version/distro: default to userspace-networking on Crostini
cros-garcon NULL-derefs on cold-boot netlink enumeration when
tailscale0 is present, preventing the Crostini container and
ChromeOS Terminal from starting cleanly. This is an upstream
ChromiumOS bug in cros-garcon; tailscaled can work around it
by defaulting to userspace-networking mode on Crostini.

Tailscale SSH continues to work via tailscaled's netstack.
Users can override with --tun=tailscale0 on ChromeOS builds
where cros-garcon is fixed.

Crostini is detected via /opt/google/cros-containers/bin/garcon,
which is present in every Crostini penguin container.

ssh/tailssh extends the existing Debian default-PATH case to
cover Crostini, since Crostini is Debian-based and benefits
from the same SSH PATH defaults.

RELNOTE: Crostini now defaults to userspace-networking.

Fixes #19488
Updates #12090

Signed-off-by: ferrumclaudepilgrim <ferrumclaudepilgrim@users.noreply.github.com>
2026-06-01 17:40:07 -07:00
Simon Law 92bfda580c cmd/tailscale/cli: fix time in tailscale routecheck (#19956)
When running `tailscale netcheck`, the reported timestamp used to be
in UTC and formatted according to RFC 3339 with a `T` to separate the
date from the time:

	sfllaw@h2co3:~$ tailscale netcheck | head -n3

	Report:
		* Time: 2026-06-01T21:12:32.252620138Z

This is machine-readable time leaking out to the user interface. Times
in normal commands are formatted for humans to read:

	sfllaw@h2co3:~$ date
	Mon 01 Jun 2026 02:39:14 PM PDT
	sfllaw@h2co3:~$ journalctl -t tailscaled | tail -n1
	Jun 01 14:35:21 h2co3 tailscaled[3328921]: wgengine: sending TSMP disco key advertisement to 100.90.144.102
	sfllaw@h2co3:~$ timedatectl show
	Timezone=America/Los_Angeles
	LocalRTC=no
	CanNTP=yes
	NTP=yes
	NTPSynchronized=yes
	TimeUSec=Mon 2026-06-01 14:38:32 PDT
	RTCTimeUSec=Mon 2026-06-01 14:38:32 PDT
	sfllaw@h2co3:~$ uptime --since
	2026-05-15 07:37:45

This PR makes the times printed by the CLI commands consistent:

- For `tailscale routecheck`, it now prints local time as
  `2026-05-15 07:37:45-07:00`.
- For `netlogfmt`, it has always printed local time with a space,
  but now includes the time zone.
- All machine-readable outputs continue to be standard RFC 3339 in
  UTC, i.e. `--format=json`.

As part of a general cleanup, this PR also adds standard common
time.Format layouts as tstime constants.

Fixes #19928

Signed-off-by: Simon Law <sfllaw@tailscale.com>
2026-06-01 16:12:08 -07:00
Patrick O'Doherty 651049ec19 ssh/tailssh: reject dangerous LD_/DYLD_ env vars in acceptEnv filtering (#19914)
Block dynamic linker environment variables (LD_PRELOAD, LD_LIBRARY_PATH,
DYLD_INSERT_LIBRARIES, and friends) from being forwarded regardless of
acceptEnv policy, preventing privilege escalation via wildcard patterns
like "*".

We are not aware of any legitimate use of these variables so they are
safe to exclude from being passed.

Thanks to Tim Sageser (dtrsecurity) for this report.

Updates tailscale/corp#42033

Signed-off-by: Patrick O'Doherty <patrick@tailscale.com>
2026-06-01 09:19:27 -07:00
Brad Fitzpatrick 3e34e721e8 tsnet: add opt-in SSH support (Server.ListenSSH)
This adds tsnet.Server.ListenSSH which, if the SSH feature is linked,
returns a net.Listener whose Accept yields *tailssh.Session values (as
net.Conn). This lets tsnet apps accept incoming SSH connections to
implement custom TUI applications.

Basic apps can use net.Conn directly (Read/Write/Close). Rich apps
import ssh/tailssh and type-assert for peer identity, PTY, signals,
etc. If feature/ssh isn't imported, ListenSSH returns an error.

Includes a demo guess-the-number game in tsnet/example/ssh-game.

Updates tailscale/corp#37839

Change-Id: I4e7c3c96afb030cdf4da8f2d8b2253820628129a
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-05-30 14:17:50 -07:00
Brad Fitzpatrick 159cf8707a ipn/ipnlocal, all: split LocalBackend.NetMap into NetMapNoPeers / NetMapWithPeers
Add two narrower accessors alongside the existing
[LocalBackend.NetMap], with docs that distinguish their semantics:

  - NetMapNoPeers: cheap (returns the cached *netmap.NetworkMap with
    a possibly-stale Peers slice). For callers that only read non-Peers
    fields like SelfNode, DNS, PacketFilter, capabilities.
  - NetMapWithPeers: documented as returning an up-to-date Peers slice.
    For callers that genuinely need to iterate Peers or call
    PeerByXxx.

Mark the existing NetMap deprecated and point readers at the two new
accessors. NetMap, NetMapNoPeers, and NetMapWithPeers all currently
return the same value (b.currentNode().NetMap()): this commit is a
no-op behaviorally, just a renaming and migration of in-tree callers.
A subsequent change in the same series will switch
NetMapWithPeers to actually rebuild the Peers slice from the live
per-node-backend peers map (O(N) per call), at which point the
distinction between the two new accessors becomes load-bearing.

Migrate in-tree callers to the appropriate accessor based on what
fields they read:

  - NetMapNoPeers (most common): localapi handlers, peerapi accept,
    GetCertPEMWithValidity, web client noise request, doctor DNS
    resolver check, tsnet CertDomains/TailscaleIPs, ssh/tailssh
    SSH-policy/cap reads, several LocalBackend internals
    (isLocalIP, allowExitNodeDNSProxyToServeName, pauseForNetwork
    nil-check, serve config).
  - NetMapWithPeers: writeNetmapToDiskLocked (persist full netmap to
    disk for fast restart), PeerByTailscaleIP lookup.

Tests still call the legacy NetMap; they'll see the deprecation
warning but otherwise behave identically.

Also add two pieces of plumbing the next change in this series will
need, but which are already useful on their own:

  - [client/local.GetDebugResultJSON]: a generic [Client.DebugResultJSON]
    that decodes directly into a target type T, avoiding the
    marshal/unmarshal roundtrip callers otherwise need.
  - localapi "current-netmap" debug action: returns the current
    netmap (with peers) as JSON. Documented as debug-only — the
    netmap.NetworkMap shape is internal and may change without notice.

This commit is part of a series breaking up a larger change for
review; on its own it is a no-op refactor.

Updates #12542

Change-Id: Idbb30707414f8da3149c44ca0273262708375b02
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-04-30 11:14:06 -07:00
Alex Chan 1841a93ab2 ssh/tailssh: mark TestSSHRecordingCancelsSessionsOnUploadFailure as flaky (again)
This test is still flaking on macOS, so mark it as such so we can track
and investigate further.

Updates #7707

Change-Id: I640da3c1068a90a9815caab2df9431bceb01f846
Signed-off-by: Alex Chan <alexc@tailscale.com>
2026-04-29 14:22:09 +01:00
Brad Fitzpatrick e2fa9ff140 ssh/tailssh: speed up SSH integration tests
Parallelize the SSH integration tests across OS targets and reduce
per-container overhead:

- CI: use GitHub Actions matrix strategy to run all 4 OS containers
  (ubuntu:focal, ubuntu:jammy, ubuntu:noble, alpine:latest) in parallel
  instead of sequentially (~4x wall-clock improvement)

- Makefile: run docker builds in parallel for local dev too

- Dockerfile: consolidate ~20 separate RUN commands into 5 (one per
  test phase), eliminating Docker layer overhead. Combine test binary
  invocations where no state mutation is needed between them. Fix a bug
  where TestDoDropPrivileges was silently not being run (was passed as a
  second positional arg to -test.run instead of using regex alternation).

- TestMain: replace tail -F + 2s sleep with synchronous log read,
  eliminating 2s overhead per test binary invocation. Set debugTest once
  in TestMain instead of redundantly in each test function.

- session.read(): close channel on EOF so non-shell tests return
  immediately instead of waiting for the 1s silence timeout.

Updates #19244

Change-Id: I2cc8588964fbce0dd7b654fb94e7ff33440b8584
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-04-13 14:18:27 -07:00
Brad Fitzpatrick aa9a76cf30 ssh/tailssh: gofmt
I'm not sure how this file got into the repo without gofmt.

Maybe gofmt rules changed in some Go release?

Updates #cleanup

Change-Id: Ia8bd46e29f116f7fbfca11be80c8ef48699cd9f2
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-04-13 11:09:13 -07:00
Brad Fitzpatrick cf59a6fb23 .github, tool/listpkgs: automatically find tests which use tstest.RequireRoot
Updates tailscale/corp#40007

Change-Id: I677d3d9e276cb6633a14ac07e4b58ea08e52fac4
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-04-10 16:22:05 -07:00
Brad Fitzpatrick 5e81840b57 tstest: add RequireRoot helper
Start using a common helper for tests to declare that they require root.

This is step 1. A later step will then make this helper track which tests were
skipped so a subsequent pass will run these test as root.

Updates tailscale/corp#40007

Change-Id: I4979e1def0fa3691d38c83f48c89aaa443e7f62e
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-04-10 10:48:50 -07:00
Andrew Dunham 27e6fed0c1 ssh/tailssh: fix default PATH for Debian
Validated against a modern Debian install, fixes a typo.

Updates #cleanup

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I7b26012f54dbd2f0f9fea98722e8edc2fe97645a
2026-04-09 11:57:40 -04:00
Brad Fitzpatrick 2b1cfa7c4d ssh/tailssh: fix race in session termination message delivery
When a recording upload fails mid-session, the recording goroutine
cancels the session context. This triggers two concurrent paths:
exec.CommandContext kills the process (causing cmd.Wait to return),
and killProcessOnContextDone tries to write the termination message
via exitOnce.Do. If cmd.Wait returns first, the main goroutine's
exitOnce.Do(func(){}) steals the once, and the termination message
is never written to the client.

Fix by waiting for killProcessOnContextDone to finish writing the
termination message (via <-ss.exitHandled) before claiming exitOnce,
when the context is already done.

Also fix the fallback path when launchProcess itself fails due to
context cancellation: use SSHTerminationMessage() with the correct
"\r\n\r\n" framing instead of fmt.Fprintf with the internal error
string.

Deflakes TestSSHRecordingCancelsSessionsOnUploadFailure, which was
failing consistently at a low rate due to the exitOnce race. After
this fix, flakestress passes with 8,668 runs, 0 failures.

Fixes #7707 (again. hopefully for good.)

Change-Id: I5ab911c71574db8d3f9d979fb839f273be51ecf9
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-04-07 05:31:16 -07:00
Kristoffer Dalby dd3b613787 ssh: replace tempfork with tailscale/gliderssh
Brings in a newer version of Gliderlabs SSH with added socket forwarding support.

Fixes #12409
Fixes #5295

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>
2026-04-07 11:59:38 +01:00
Kristoffer Dalby 82fa218c4a tempfork/gliderlabs/ssh: remove tempfork
Updates #12409
Updates #5295

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>
2026-04-07 11:59:38 +01:00
Brad Fitzpatrick 4111d4be4b ssh/tailssh: fix integration test hang due to missing host keys
Commit f905871fb moved host key generation from the ipnLocalBackend
interface (GetSSH_HostKeys) to the standalone getHostKeys function,
which requires either system host keys in /etc/ssh/ or a valid
TailscaleVarRoot to generate keys into. The testBackend returned ""
for TailscaleVarRoot, and the Docker test containers only install
openssh-client (no server host keys), so getHostKeys always failed.

When getHostKeys fails, HandleSSHConn returns the error but never
closes the TCP connection, so SSH clients hang forever waiting for
the server hello.

Fix by creating a temp directory in TestMain and returning it from
testBackend.TailscaleVarRoot().

Regression from f905871fb #18949 ("ipn/ipnlocal, feature/ssh: move SSH code
out of LocalBackend to feature").

I was apparently too impatient to wait for the test to complete
and didn't connect the dots: https://github.com/tailscale/tailscale/actions/runs/22930275950

We should make that test faster (#19244) for the patience issue, but
also fail more nicely if this happens in the future.

Updates #19244

Change-Id: If82393b8f35413b04174e6f7d09a1ee3a2125a6b
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-04-06 09:29:31 -07:00
Brad Fitzpatrick 5ef3713c9f cmd/vet: add subtestnames analyzer; fix all existing violations
Add a new vet analyzer that checks t.Run subtest names don't contain
characters requiring quoting when re-running via "go test -run". This
enforces the style guide rule: don't use spaces or punctuation in
subtest names.

The analyzer flags:
- Direct t.Run calls with string literal names containing spaces,
  regex metacharacters, quotes, or other problematic characters
- Table-driven t.Run(tt.name, ...) calls where tt ranges over a
  slice/map literal with bad name field values

Also fix all 978 existing violations across 81 test files, replacing
spaces with hyphens and shortening long sentence-like names to concise
hyphenated forms.

Updates #19242

Change-Id: Ib0ad96a111bd8e764582d1d4902fe2599454ab65
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-04-05 15:52:51 -07:00
Brad Fitzpatrick f905871fb1 ipn/ipnlocal, feature/ssh: move SSH code out of LocalBackend to feature
This makes tsnet apps not depend on x/crypto/ssh and locks that in with a test.

It also paves the wave for tsnet apps to opt-in to SSH support via a
blank feature import in the future.

Updates #12614

Change-Id: Ica85628f89c8f015413b074f5001b82b27c953a9
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-03-10 17:27:17 -07:00
Brad Fitzpatrick 99e3e9af51 ssh/tailssh: mark TestSSHRecordingCancelsSessionsOnUploadFailure as flaky again
Updates #7707

Change-Id: I98cdace78cd5060643894fb0c9be02574edb2894
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-03-10 15:49:54 -07:00
Brad Fitzpatrick 633e892164 ssh/tailssh: fix race between termination message write and session teardown
When a recording upload fails mid-session, killProcessOnContextDone
writes the termination message to ss.Stderr() and kills the process.
Meanwhile, run() takes the ss.ctx.Done() path and proceeds to
ss.Exit(), which tears down the SSH channel. The termination message
write races with the channel teardown, so the client sometimes never
receives it.

Fix by adding an exitHandled channel that killProcessOnContextDone
closes when done. run() now waits on this channel after ctx.Done()
fires, ensuring the termination message is fully written before
the SSH channel is torn down.

Fixes #7707

Change-Id: Ib60116c928d3af46d553a4186a72963c2c731e3e
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-03-09 14:11:07 -07:00
Brad Fitzpatrick bd2a2d53d3 all: use Go 1.26 things, run most gofix modernizers
I omitted a lot of the min/max modernizers because they didn't
result in more clear code.

Some of it's older "for x := range 123".

Also: errors.AsType, any, fmt.Appendf, etc.

Updates #18682

Change-Id: I83a451577f33877f962766a5b65ce86f7696471c
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-03-06 13:32:03 -08:00
Brad Fitzpatrick 2a64c03c95 types/ptr: deprecate ptr.To, use Go 1.26 new
Updates #18682

Change-Id: I62f6aa0de2a15ef8c1435032c6aa74a181c25f8f
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-03-05 20:13:18 -08:00
Brad FitzpatrickandGesa Stupperich a6390ca008 ssh/tailssh: fix data race on conn auth state in OnPolicyChange
OnPolicyChange can observe a conn in activeConns before authentication
completes. The previous `c.info == nil` guard was itself a data race
against clientAuth writing c.info, and even when c.info appeared
non-nil, c.localUser could still be nil, causing a nil pointer
dereference at c.localUser.Username.

Add an authCompleted atomic.Bool to conn, stored true after all auth
fields are written in clientAuth. OnPolicyChange checks this atomic
instead of c.info, which provides the memory barrier guaranteeing all
prior writes are visible to the concurrent reader.

Updates tailscale/corp#36268 (fixes, but we might want to cherry-pick)

Co-authored-by: Gesa Stupperich <gesa@tailscale.com>
Change-Id: I4c69843541f5f9f04add9bf431e320c65a203a39
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-02-16 13:02:46 -10:00
Brad Fitzpatrick d26d3fcb95 .github/workflows: add macos runner
Fixes #18118

Change-Id: I118fcc6537af9ccbdc7ce6b78134e8059b0b5ccf
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-02-09 15:09:19 -08:00
Will Norris 3ec5be3f51 all: remove AUTHORS file and references to it
This file was never truly necessary and has never actually been used in
the history of Tailscale's open source releases.

A Brief History of AUTHORS files
---

The AUTHORS file was a pattern developed at Google, originally for
Chromium, then adopted by Go and a bunch of other projects. The problem
was that Chromium originally had a copyright line only recognizing
Google as the copyright holder. Because Google (and most open source
projects) do not require copyright assignemnt for contributions, each
contributor maintains their copyright. Some large corporate contributors
then tried to add their own name to the copyright line in the LICENSE
file or in file headers. This quickly becomes unwieldy, and puts a
tremendous burden on anyone building on top of Chromium, since the
license requires that they keep all copyright lines intact.

The compromise was to create an AUTHORS file that would list all of the
copyright holders. The LICENSE file and source file headers would then
include that list by reference, listing the copyright holder as "The
Chromium Authors".

This also become cumbersome to simply keep the file up to date with a
high rate of new contributors. Plus it's not always obvious who the
copyright holder is. Sometimes it is the individual making the
contribution, but many times it may be their employer. There is no way
for the proejct maintainer to know.

Eventually, Google changed their policy to no longer recommend trying to
keep the AUTHORS file up to date proactively, and instead to only add to
it when requested: https://opensource.google/docs/releasing/authors.
They are also clear that:

> Adding contributors to the AUTHORS file is entirely within the
> project's discretion and has no implications for copyright ownership.

It was primarily added to appease a small number of large contributors
that insisted that they be recognized as copyright holders (which was
entirely their right to do). But it's not truly necessary, and not even
the most accurate way of identifying contributors and/or copyright
holders.

In practice, we've never added anyone to our AUTHORS file. It only lists
Tailscale, so it's not really serving any purpose. It also causes
confusion because Tailscalars put the "Tailscale Inc & AUTHORS" header
in other open source repos which don't actually have an AUTHORS file, so
it's ambiguous what that means.

Instead, we just acknowledge that the contributors to Tailscale (whoever
they are) are copyright holders for their individual contributions. We
also have the benefit of using the DCO (developercertificate.org) which
provides some additional certification of their right to make the
contribution.

The source file changes were purely mechanical with:

    git ls-files | xargs sed -i -e 's/\(Tailscale Inc &\) AUTHORS/\1 contributors/g'

Updates #cleanup

Change-Id: Ia101a4a3005adb9118051b3416f5a64a4a45987d
Signed-off-by: Will Norris <will@tailscale.com>
2026-01-23 15:49:45 -08:00
James Tucker 39a61888b8 ssh/tailssh: send audit messages on SSH login (Linux)
Send LOGIN audit messages to the kernel audit subsystem on Linux
when users successfully authenticate to Tailscale SSH. This provides
administrators with audit trail integration via auditd or journald,
recording details about both the Tailscale user (whois) and the
mapped local user account.

The implementation uses raw netlink sockets to send AUDIT_USER_LOGIN
messages to the kernel audit subsystem. It requires CAP_AUDIT_WRITE
capability, which is checked at runtime. If the capability is not
present, audit logging is silently skipped.

Audit messages are sent to the kernel (pid 0) and consumed by either
auditd (written to /var/log/audit/audit.log) or journald (available
via journalctl _TRANSPORT=audit), depending on system configuration.

Note: This may result in duplicate messages on a system where
auditd/journald audit logs are enabled and the system has and supports
`login -h`. Sadly Linux login code paths are still an inconsistent wild
west so we accept the potential duplication rather than trying to avoid
it.

Fixes #18332

Signed-off-by: James Tucker <james@tailscale.com>
2026-01-05 16:53:05 -08:00
James Tucker 41662f5128 ssh/tailssh: fix incubator tests on macOS arm64
Perform a path check first before attempting exec of `true`.

Try /usr/bin/true first, as that is now and increasingly so, the more
common and more portable path.

Fixes tests on macOS arm64 where exec was returning a different kind of
path error than previously checked.

Updates #16569

Signed-off-by: James Tucker <james@tailscale.com>
2025-11-17 16:20:46 -08:00
Brad Fitzpatrick 01e645fae1 util/backoff: rename logtail/backoff package to util/backoff
It has nothing to do with logtail and is confusing named like that.

Updates #cleanup
Updates #17323

Change-Id: Idd34587ba186a2416725f72ffc4c5778b0b9db4a
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2025-09-28 11:55:07 -07:00
Alex Chan 312582bdbf ssh/tailssh: mark TestSSHRecordingCancelsSessionsOnUploadFailure as flaky
Updates https://github.com/tailscale/tailscale/issues/7707

Signed-off-by: Alex Chan <alexc@tailscale.com>
2025-09-17 11:27:00 +01:00
Claus Lensbøl 2015ce4081 health,ipn/ipnlocal: introduce eventbus in heath.Tracker (#17085)
The Tracker was using direct callbacks to ipnlocal. This PR moves those
to be triggered via the eventbus.

Additionally, the eventbus is now closed on exit from tailscaled
explicitly, and health is now a SubSystem in tsd.

Updates #15160

Signed-off-by: Claus Lensbøl <claus@tailscale.com>
2025-09-16 11:25:29 -04:00
M. J. Fromberger 67514f5eb2 ssh/tailssh: fix path of "true" on Darwin (#16569)
This is a follow-up to #15351, which fixed the test for Linux but not for
Darwin, which stores its "true" executable in /usr/bin instead of /bin.
Try both paths when not running on Windows.

In addition, disable CGo in the integration test build, which was causing the
linker to fail. These tests do not need CGo, and it appears we had some version
skew with the base image on the runners.

In addition, in error cases the recover step of the permissions check was
spuriously panicking and masking the "real" failure reason. Don't do that check
when a command was not produced.

Updates #15350

Change-Id: Icd91517f45c90f7554310ebf1c888cdfd109f43a
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>
2025-07-16 08:08:59 -07:00
Percy Wegmann 1635ccca27 ssh/tailssh: display more useful error messages when authentication fails
Also add a trailing newline to error banners so that SSH client messages don't print on the same line.

Updates tailscale/corp#29138

Signed-off-by: Percy Wegmann <percy@tailscale.com>
2025-06-03 14:00:04 -05:00
Brad Fitzpatrick 7a5af6e6e7 ssh/tailssh: exclude Android from Linux build tags
As noted in #16048, the ./ssh/tailssh package failed to build on
Android, because GOOS=android also matches the "linux" build
tag. Exclude Android like iOS is excluded from macOS (darwin).

This now works:

    $ GOOS=android go install ./ipn/ipnlocal ./ssh/tailssh

The original PR at #16048 is also fine, but this stops the problem
earlier.

Updates #16048

Change-Id: Ie4a6f6966a012e510c9cb11dd0d1fa88c48fac37
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2025-05-22 20:02:59 -07:00
Nick Khyl b70c0c50fd ssh/tailssh: fix data race during execution of test
In tailssh.go:1284, (*sshSession).startNewRecording starts a fire-and-forget goroutine that can
outlive the test that triggered its creation. Among other things, it uses ss.logf, and may call it
after the test has already returned. Since we typically use (*testing.T).Logf as the logger,
this results in a data race and causes flaky tests.

Ideally, we should fix the root cause and/or use a goroutines.Tracker to wait for the goroutine
to complete. But with the release approaching, it's too risky to make such changes now.

As a workaround, we update the tests to use tstest.WhileTestRunningLogger, which logs to t.Logf
while the test is running and disables logging once the test finishes, avoiding the race.

While there, we also fix TestSSHAuthFlow not to use log.Printf.

Updates #15568
Updates #7707 (probably related)

Signed-off-by: Nick Khyl <nickk@tailscale.com>
2025-05-10 10:44:11 -05:00
Simon Law 3c98964065 ssh/tailssh: chdir to user's homedir when directly running a command (#15351)
Commit 4b525fdda (ssh/tailssh: only chdir incubator process to user's
homedir when necessary and possible, 2024-08-16) defers changing the
working directory until the incubator process drops its privileges.

However, it didn't account for the case where there is no incubator
process, because no tailscaled was found on the PATH. In that case, it
only intended to run `tailscaled be-child` in the root directory but
accidentally ran everything there.

Fixes: #15350

Signed-off-by: Simon Law <sfllaw@sfllaw.ca>
2025-05-09 12:55:57 -07:00
David Anderson 5399fa159a net/netmon: publish events to event bus
Updates #15160

Signed-off-by: David Anderson <dave@tailscale.com>
2025-04-16 10:10:45 -07:00
M. J. Fromberger deb0b255ff all: update the tsd.System constructor name (#15372)
Replace NewSystemWithEventBus with plain NewSystem, and update all usage.
See https://github.com/tailscale/tailscale/pull/15355#discussion_r2003910766

Updates #15160

Change-Id: I64d337f09576b41d9ad78eba301a74b9a9d6ebf4
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>
2025-04-16 10:10:45 -07:00
M. J. Fromberger ffb22ee353 all: construct new System values with an event bus pre-populated
Although, at the moment, we do not yet require an event bus to be present, as
we start to add more pieces we will want to ensure it is always available.  Add
a new constructor and replace existing uses of new(tsd.System) throughout.
Update generated files for import changes.

Updates #15160

Change-Id: Ie5460985571ade87b8eac8b416948c7f49f0f64b
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>
2025-04-16 10:10:45 -07:00
Brad Fitzpatrick b3953ce0c4 ssh/tailssh: add Plan 9 support for Tailscale SSH
Updates #5794

Change-Id: I7b05cd29ec02085cb503bbcd0beb61bf455002ac
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2025-04-02 07:36:04 -07:00
Brad Fitzpatrick e38e5c38cc ssh/tailssh: fix typo in forwardedEnviron method, add docs
And don't return a comma-separated string. That's kinda weird
signature-wise, and not needed by half the callers anyway. The callers
that care can do the join themselves.

Updates #cleanup

Change-Id: Ib5ad51a3c6b663d868eba14fe9dc54b2609cfb0d
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2025-03-10 20:28:36 -07:00
Percy Wegmann db231107a2 ssh/tailssh: accept passwords and public keys
Some clients don't request 'none' authentication. Instead, they immediately supply
a password or public key. This change allows them to do so, but ignores the supplied
credentials and authenticates using Tailscale instead.

Updates #14922

Signed-off-by: Percy Wegmann <percy@tailscale.com>
2025-02-13 11:29:45 -06:00