When a client sends an SSH session before the shell process ends, Teleport sends the SIGKILL signal to the subprocess. This causes the still-leaving shell to be resigned to PID 1 and live forever.
This PR tried to stop the terminal first before killing the subprocess to prevent the terminal from living forever.
Closes#13335Closes#6245Closes#4469
* Prevent "session.start" from being overwritten by "session.exec"
The `session.exec` event was not being passed through the session
recorder, which resulted in said event having an event index of 0.
This caused the original `session.start` event which also has an
`eid` of 0 to be overwritten by the `session.exec` event.
By emitting the `session.exec` event via the same mechanism as the
`session.start` event it gets a proper event index and no longer
overwrites the `session.start`.
Closes#13622
Invert the relationship of `lib/srv` and `lib/bpf`,
`lib/restrictedsession` such that `lib/bpf` is only imported in
`lib/srv/regular`. Since not everything is built with the `bpf`
tag it's important to reduce the surface area of `lib/bpf` such
that it isn't inadvertantly imported. For instance it was entirely
possible to import a package in `tsh` that transitively
depends on `lib/bpf` - which breaks the build since `tsh` is not
compiled with the `bpf` tag.
By refactoring the `srv.Server` interface not to use the `bpf.BPF`
and `restrictedsession.Manager` interfaces directly anything that
imports `lib/srv` now won't require that `-tags=bpf` is set in
order to compile.
- Don't assume an explicit $GOPATH is set
- Remove golint from linters - it's been deprecated for over a year
and golangci-lint prints a warning instead of running it.
Adds the ability to block network traffic on SSH sessions.
The deny/allow lists of IPs are specified in teleport.yaml file.
Supports both IPv4 and IPv6 communication.
This feature currently relies on enhanced recording for
cgroup management so that needs to be enabled as well.
-- Design rationale:
This patch uses Linux Security Module (LSM) hooks, specifically
security_socket_connect and security_socket_sendmsg, to control
egress traffic. The LSM provides two advantages over socket filtering
program types.
- It's executed early enough that the task information is available.
This makes it easy to report PID, COMM, etc.
- It becomes a model for extending restrictions beyond networking.
The set of enforced cgroups is stored in a BPF hash map and the
deny/allow lists are stored in BPF trie maps. An IP address is
first checked against the allow list. If found, it's checked for
an override in the deny list. The policy is default deny. However,
the absence of the NetworkRestrictions API object is allow all.
IPv4 addresses are additionally registered in IPv6 trie (as mapped)
to account for dual stacks. However it is unclear if this is sufficient
as 4-to-6 transition methods utilize a multitude of translation and
tunneling methods.
* Added support for connecting API client through tunnel proxy and web proxy addresses (with identity file).
* Added concurrent dialing logic to dial several possible dialing combinations and seamlessly return the first client to connect.
* mfa: put device UUID in MFAVerified cert extensions
Instead of just a bool, add the device UUID. This will be used in audit
events when a session is started using MFA-issued certs.
* Add WithMFA to session-related audit events
Also extract a common function for parsing SSH certs.
This commit introduces GRPC API for streaming sessions.
It adds structured events and sync streaming
that avoids storing events on disk.
You can find design in rfd/0002-streaming.md RFD.
Changes agent channel setup behavior to be consistent
openssh by having servers lazily request agent channels
when they are needed, rather than immediately starting a
single connection-wide channel as soon as forwarding is
requested. Fixes an issue introduced in #3613 which
caused openssh clients to hang on exit due to persistent
agent channel.
To execute an SSH command, Teleport re-executes itself and execs the
command from this child process:
teleport -> teleport exec -> sh -c "user command"
Both parent teleport processes could exit unexpectedly (from SIGKILL or
even connection interruption).
Make sure all child processes get cleaned up and not orphaned to PID 1:
- teleport exec via SIGQUIT to request graceful shutdown
- user command via SIGKILL because it might ignore other signals
Spring cleaning!
A very mechanical cleanup using several linters (unused, deadcode,
structcheck). Build and tests still pass so no behavior should be
affected.
Added support for reexec during port forwarding. This allows Teleport
nodes to run PAM code before port forwarding requests. This makes any
memory leaks in PAM code less dangerous as well as bringing port
forwarding logic in-line with execution requests (exec or shell).
Refactored launching of shell to call PAM first. This allows a PAM
module to create the user and home directory before attempting to launch
a shell for said user.
To do this the command passed to Teleport during re-exec has changed.
Before the Teleport master process would resolve the user fully (UID,
GUID, supplementary groups, shell, home directory) before re-launching
itself to then launch a shell. However, if PAM is used to create the
user on the fly and PAM has not been called yet, this will fail.
Instead that work has now been pushed to occur in the child process.
This means the Teleport master process now creates a payload with the
minimum needed from *srv.ServerContext and will then re-exec itself. The
child process will call PAM and then attempt to resolve the user (UID,
GUID, supplementary groups, shell, home directory).
Added package cgroup to orchestrate cgroups. Only support for cgroup2
was added to utilize because cgroup2 cgroups have unique IDs that can be
used correlated with BPF events.
Added bpf package that contains three BPF programs: execsnoop,
opensnoop, and tcpconnect. The bpf package starts and stops these
programs as well correlating their output with Teleport sessions
and emitting them to the audit log.
Added support for Teleport to re-exec itself before launching a shell.
This allows Teleport to start a child process, capture it's PID, place
the PID in a cgroup, and then continue to process. Once the process is
continued it can be tracked by it's cgroup ID.
Reduced the total number of connections to a host so Teleport does not
quickly exhaust all file descriptors. Exhausting all file descriptors
happens very quickly when disk events are emitted to the audit log which
are emitted at a very high rate.
Added tarballs for exec sessions. Updated session.start and session.end
events with additional metadata. Updated the format of session tarballs
to include enhanced events.
Added file configuration for enhanced session recording. Added code to
startup enhanced session recording and pass package to SSH nodes.
When emitting session related events, emit them with the ID of the host
not of the server. This is because the forwarding server has a randomly
generated ID that will note validate with TLS identity that connects to
the Auth Server.
Jakub Nyckowski