This allows passing through any environment variables that we set ourselves, for example DBUS_SESSION_BUS_ADDRESS.
Updates #11175
Co-authored-by: Mario Minardi <mario@tailscale.com>
Signed-off-by: Percy Wegmann <percy@tailscale.com>
Add logic to set environment variables that match the SSH rule's
`acceptEnv` settings in the SSH session's environment.
Updates https://github.com/tailscale/corp/issues/22775
Signed-off-by: Mario Minardi <mario@tailscale.com>
Add logic for parsing and matching against our planned format for
AcceptEnv values. Namely, this supports direct matches against string
values and matching where * and ? are treated as wildcard characters
which match against an arbitrary number of characters and a single
character respectively.
Actually using this logic in non-test code will come in subsequent
changes.
Updates https://github.com/tailscale/corp/issues/22775
Signed-off-by: Mario Minardi <mario@tailscale.com>
this commit changes usermetrics to be non-global, this is a building
block for correct metrics if a go process runs multiple tsnets or
in tests.
Updates #13420
Updates tailscale/corp#22075
Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>
And update a few callers as examples of motivation. (there are a
couple others, but these are the ones where it's prettier)
Updates #cleanup
Change-Id: Ic8c5cb7af0a59c6e790a599136b591ebe16d38eb
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
In prep for updating to new staticcheck required for Go 1.23.
Updates #12912
Change-Id: If77892a023b79c6fa798f936fc80428fd4ce0673
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Instead of changing the working directory before launching the incubator process,
this now just changes the working directory after dropping privileges, at which
point we're more likely to be able to enter the user's home directory since we're
running as the user.
For paths that use the 'login' or 'su -l' commands, those already take care of changing
the working directory to the user's home directory.
Fixes#13120
Signed-off-by: Percy Wegmann <percy@tailscale.com>
This involved the following:
1. Pass the su command path as first of args in call to unix.Exec to make sure that busybox sees the correct program name.
Busybox is a single executable userspace that implements various core userspace commands in a single binary. You'll
see it used via symlinking, so that for example /bin/su symlinks to /bin/busybox. Busybox knows that you're trying
to execute /bin/su because argv[0] is '/bin/su'. When we called unix.Exec, we weren't including the program name for
argv[0], which caused busybox to fail with 'applet not found', meaning that it didn't know which command it was
supposed to run.
2. Tell su to whitelist the SSH_AUTH_SOCK environment variable in order to support ssh agent forwarding.
3. Run integration tests on alpine, which uses busybox.
4. Increment CurrentCapabilityVersion to allow turning on SSH V2 behavior from control.
Fixes#12849
Signed-off-by: Percy Wegmann <percy@tailscale.com>
cmd/k8s-operator,k8s-operator/sessionrecording,sessionrecording,ssh/tailssh: refactor session recording functionality
Refactor SSH session recording functionality (mostly the bits related to
Kubernetes API server proxy 'kubectl exec' session recording):
- move the session recording bits used by both Tailscale SSH
and the Kubernetes API server proxy into a shared sessionrecording package,
to avoid having the operator to import ssh/tailssh
- move the Kubernetes API server proxy session recording functionality
into a k8s-operator/sessionrecording package, add some abstractions
in preparation for adding support for a second streaming protocol (WebSockets)
Updates tailscale/corp#19821
Signed-off-by: Irbe Krumina <irbe@tailscale.com>
cmd/k8s-operator,ssh/tailssh,tsnet: optionally record kubectl exec sessions
The Kubernetes operator's API server proxy, when it receives a request
for 'kubectl exec' session now reads 'RecorderAddrs', 'EnforceRecorder'
fields from tailcfg.KubernetesCapRule.
If 'RecorderAddrs' is set to one or more addresses (of a tsrecorder instance(s)),
it attempts to connect to those and sends the session contents
to the recorder before forwarding the request to the kube API
server. If connection cannot be established or fails midway,
it is only allowed if 'EnforceRecorder' is not true (fail open).
Updates tailscale/corp#19821
Signed-off-by: Irbe Krumina <irbe@tailscale.com>
Co-authored-by: Maisem Ali <maisem@tailscale.com>
This allows the SSH_AUTH_SOCK environment variable to work inside of
su and agent forwarding to succeed.
Fixes#12467
Signed-off-by: Percy Wegmann <percy@tailscale.com>
Previously, we were registering TCP and UDP connections in the same map,
which could result in erroneously removing a mapping if one of the two
connections completes while the other one is still active.
Add a "proto string" argument to these functions to avoid this.
Additionally, take the "proto" argument in LocalAPI, and plumb that
through from the CLI and add a new LocalClient method.
Updates tailscale/corp#20600
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I35d5efaefdfbf4721e315b8ca123f0c8af9125fb
Checking in the incubator as this used to do fails because
the getenforce command is not on the PATH.
Updates #12442
Signed-off-by: Percy Wegmann <percy@tailscale.com>
This allows pam authentication to run for ssh sessions, triggering
automation like pam_mkhomedir.
Updates #11854
Signed-off-by: Percy Wegmann <percy@tailscale.com>
In prep for it being required in more places.
Updates #11874
Change-Id: Ib743205fc2a6c6ff3d2c4ed3a2b28cac79156539
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Since the tailscaled binaries that we distribute are static and don't
link cgo, we previously wouldn't fetch group IDs that are returned via
NSS. Try shelling out to the 'id' command, similar to how we call
'getent', to detect such cases.
Updates #11682
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I9bdc938bd76c71bc130d44a97cc2233064d64799
Since we already track active SSH connections, it's not hard to
proactively reject updates until those finish. We attempt to do the same
on the control side, but the detection latency for new connections is in
the minutes, which is not fast enough for common short sessions.
Handle a `force=true` query parameter to override this behavior, so that
control can still trigger an update on a server where some long-running
abandoned SSH session is open.
Updates https://github.com/tailscale/corp/issues/18556
Signed-off-by: Andrew Lytvynov <awly@tailscale.com>
ErrDenied was added in [our fork of
x/crypto/ssh](acc6f8fe8d)
to short-circuit auth attempts once one fails.
In the case of our callbacks, this error is returned when SSH policy
check determines that a connection should not be allowed. Both
`NoClientAuthCallback` and `PublicKeyHandler` check the policy and will
fail anyway. The `fakePasswordHandler` returns true only if
`NoClientAuthCallback` succeeds the policy check, so it checks it
indirectly too.
The difference here is that a client might attempt all 2-3 auth methods
instead of just `none` but will fail to authenticate regardless.
Updates #8593
Signed-off-by: Andrew Lytvynov <awly@tailscale.com>
Run `staticcheck` with `U1000` to find unused code. This cleans up about
a half of it. I'll do the other half separately to keep PRs manageable.
Updates #cleanup
Signed-off-by: Andrew Lytvynov <awly@tailscale.com>
This takes advantage of existing functionality in ipn/ipnlocal to adjust
the local clock based on periodic time signals from the control server.
This way, when checking things like SSHRule expirations, calculations are
protected incorrectly set local clocks.
Fixestailscale/corp#15796
Signed-off-by: Percy Wegmann <percy@tailscale.com>
We were incrementing the sftp metric on regular sessions
too, not just sftp.
Updates #cleanup
Change-Id: I63027a39cffb3e03397c6e4829b1620c10fa3130
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This package is a wrapper for os/user that handles non-cgo builds,
gokrazy and user shells.
Updates tailscale/corp#15405
Signed-off-by: Andrew Lytvynov <awly@tailscale.com>
This PR removes calls to ioutil library and replaces them
with their new locations in the io and os packages.
Fixes#9034
Updates #5210
Signed-off-by: Marwan Sulaiman <marwan@tailscale.com>
If the connection provided to sftp.NewServer is closed,
Serve returns the io.EOF error verbatim from io.Reader.Read.
This is an odd error since this is an expected situation,
so we manually ignore io.EOF.
This is somewhat buggy since the sftp package itself
incorrectly reports io.EOF in cases where it should actually
be reporting io.ErrUnexpectedEOF.
See https://github.com/pkg/sftp/pull/554 which patches Serve to
return nil on clean closes and fixes buggy uses of io.ReadFull.
Fixes#8592
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
There are two race conditions in output handling.
The first race condition is due to a misuse of exec.Cmd.StdoutPipe.
The documentation explicitly forbids concurrent use of StdoutPipe
with exec.Cmd.Wait (see golang/go#60908) because Wait will
close both sides of the pipe once the process ends without
any guarantees that all data has been read from the pipe.
To fix this, we allocate the os.Pipes ourselves and
manage cleanup ourselves when the process has ended.
The second race condition is because sshSession.run waits
upon exec.Cmd to finish and then immediately proceeds to call ss.Exit,
which will close all output streams going to the SSH client.
This may interrupt any asynchronous io.Copy still copying data.
To fix this, we close the write-side of the os.Pipes after
the process has finished (and before calling ss.Exit) and
synchronously wait for the io.Copy routines to finish.
Fixes#7601
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Co-authored-by: Maisem Ali <maisem@tailscale.com>
On redhat 9 and similarly locked down systems, root user does not have
access to a users directory. This fix does not set a directory for the
incubator process and instead sets the directory when the actual process
requested by remote user is executed.
Fixes#8118
Signed-off-by: Derek Burdick <derek-burdick@users.noreply.github.com>
Trying to SSH when SELinux is enforced results in errors like:
```
➜ ~ ssh ec2-user@<ip>
Last login: Thu Jun 1 22:51:44 from <ip2>
ec2-user: no shell: Permission denied
Connection to <ip> closed.
```
while the `/var/log/audit/audit.log` has
```
type=AVC msg=audit(1685661291.067:465): avc: denied { transition } for pid=5296 comm="login" path="/usr/bin/bash" dev="nvme0n1p1" ino=2564 scontext=system_u:system_r:unconfined_service_t:s0 tcontext=unconfined_u:unconfined_r:unconfined_t:s0 tclass=process permissive=0
```
The right fix here would be to somehow install the appropriate context when
tailscale is installed on host, but until we figure out a way to do that
stop using the `login` cmd in these situations.
Updates #4908
Signed-off-by: Maisem Ali <maisem@tailscale.com>
This basically allows running services on the SSH client and reaching
them from the SSH server during the session.
Updates #6575
Signed-off-by: Maisem Ali <maisem@tailscale.com>
Max username length is increased to 256 on linux to match /usr/include/bits/local_lim.h
Fixes#8277
Signed-off-by: Derek Burdick <derek-burdick@users.noreply.github.com>
This change introduces a SSHSessionRecordingFailed event type
that is used when a session recording fails to start or fails during a
session, and the on failure indicates that it should fail open.
Updates tailscale/corp#9967
Signed-off-by: Charlotte Brandhorst-Satzkorn <charlotte@tailscale.com>
58ab66ec51 added LDAP support
for #4945 by shelling out to getdent.
It was supposed to fall back to the old method when getdent wasn't
found, but some variable name confusion (uid vs username) meant the
old path wasn't calling the right lookup function (user.LookupId
instead of user.Lookup).
Which meant that changed probably also broke FreeBSD and macOS SSH
support in addition to the reported OpenWRT regression.
The gokrazy support didn't look right either.
Fixes#8180
Change-Id: I273bbe96fe98b2517fbf0335fd476b483c051554
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
We were only closing on side of the pty/tty pair.
Close the other side too.
Thanks to @fritterhoff for reporting and debugging the issue!
Fixes#8119
Signed-off-by: Maisem Ali <maisem@tailscale.com>
The previous commit 58ab66e added ssh/tailssh/user.go as part of
working on #4945. So move some more user-related code over to it.
Updates #cleanup
Change-Id: I24de66df25ffb8f867e1a0a540d410f9ef16d7b0
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
