When a Linux system acts as an exit node or subnet router with strict
reverse path filtering (rp_filter=1), reply packets may
be dropped because they fail the RPF check. Reply packets arrive on the
WAN interface but the routing table indicates they should have arrived
on the Tailscale interface, causing the kernel to drop them.
This adds firewall rules in the mangle table to save outbound packet
marks to conntrack and restore them on reply packets before the routing
decision. When reply packets have their marks restored, the kernel uses
the correct routing table (based on the mark) and the packets pass the
rp_filter check.
Implementation adds two rules per address family (IPv4/IPv6):
- mangle/OUTPUT: Save packet marks to conntrack for NEW connections
with non-zero marks in the Tailscale fwmark range (0xff0000)
- mangle/PREROUTING: Restore marks from conntrack to packets for
ESTABLISHED,RELATED connections before routing decision and rp_filter
check
The workaround is automatically enabled when UseConnmarkForRPFilter is
set in the router configuration, which happens when subnet routes are
advertised on Linux systems.
Both iptables and nftables implementations are provided, with automatic
backend detection.
Fixes#3310Fixes#14409Fixes#12022Fixes#15815Fixes#9612
Signed-off-by: Mike O'Driscoll <mikeo@tailscale.com>
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>
Also pull out interface method only needed in Linux.
Instead of having userspace do the call into the router, just let the
router pick up the change itself.
Updates #15160
Signed-off-by: Claus Lensbøl <claus@tailscale.com>
As found by @cmol in #17423.
Updates #17423
Change-Id: I1492501f74ca7b57a8c5278ea6cb87a56a4086b9
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
So wgengine/router is just the docs + entrypoint + types, and then
underscore importing wgengine/router/osrouter registers the constructors
with the wgengine/router package.
Then tsnet can not pull those in.
Updates #17313
Change-Id: If313226f6987d709ea9193c8f16a909326ceefe7
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Now cmd/derper doesn't depend on iptables, nftables, and netlink code :)
But this is really just a cleanup step I noticed on the way to making
tsnet applications able to not link all the OS router code which they
don't use.
Updates #17313
Change-Id: Ic7b4e04e3a9639fd198e9dbeb0f7bae22a4a47a9
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit does not change the order or meaning of any eventbus activity, it
only updates the way the plumbing is set up.
Updates #15160
Change-Id: I61b863f9c05459d530a4c34063a8bad9046c0e27
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>
Instead of waiting for a designated subscription to close as a canary for the
bus being stopped, use the bus Client's own signal for closure added in #17118.
Updates #cleanup
Change-Id: I384ea39f3f1f6a030a6282356f7b5bdcdf8d7102
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>
Adds the eventbus to the router subsystem.
The event is currently only used on linux.
Also includes facilities to inject events into the bus.
Updates #15160
Signed-off-by: Claus Lensbøl <claus@tailscale.com>
The regular android app constructs its own wgengine with
additional FFI shims, so this default codepath only affects
other handcrafted buids like tsnet, which do not let the
caller customize the innards of wgengine.
Android >=14 forbids the use of netlink sockets, which makes
the standard linux router fail to initialize.
Fixes#9836
Signed-off-by: David Anderson <dave@tailscale.com>
Updates tailscale/tailscale#4136
This PR is the first round of work to move from encoding health warnings as strings and use structured data instead. The current health package revolves around the idea of Subsystems. Each subsystem can have (or not have) a Go error associated with it. The overall health of the backend is given by the concatenation of all these errors.
This PR polishes the concept of Warnable introduced by @bradfitz a few weeks ago. Each Warnable is a component of the backend (for instance, things like 'dns' or 'magicsock' are Warnables). Each Warnable has a unique identifying code. A Warnable is an entity we can warn the user about, by setting (or unsetting) a WarningState for it. Warnables have:
- an identifying Code, so that the GUI can track them as their WarningStates come and go
- a Title, which the GUIs can use to tell the user what component of the backend is broken
- a Text, which is a function that is called with a set of Args to generate a more detailed error message to explain the unhappy state
Additionally, this PR also begins to send Warnables and their WarningStates through LocalAPI to the clients, using ipn.Notify messages. An ipn.Notify is only issued when a warning is added or removed from the Tracker.
In a next PR, we'll get rid of subsystems entirely, and we'll start using structured warnings for all errors affecting the backend functionality.
Signed-off-by: Andrea Gottardo <andrea@gottardo.me>
This busybox fwmaskWorks check was added before we moved away from
using the "ip" command to using netlink directly.
So it's now just wasted work (and log spam on Gokrazy) to check the
"ip" command capabilities if we're never going to use it.
Do it lazily instead.
Updates #12277
Change-Id: I8ab9acf64f9c0d8240ce068cb9ec8c0f6b1ecee7
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
After some analysis, stateful filtering is only necessary in tailnets
that use `autogroup:danger-all` in `src` in ACLs. And in those cases
users explicitly specify that hosts outside of the tailnet should be
able to reach their nodes. To fix local DNS breakage in containers, we
disable stateful filtering by default.
Updates #12108
Signed-off-by: Andrew Lytvynov <awly@tailscale.com>
When Docker is detected on the host and stateful filtering is enabled,
Docker containers may be unable to reach Tailscale nodes (depending on
the network settings of a container). Detect Docker when stateful
filtering is enabled and print a health warning to aid users in noticing
this issue.
We avoid printing the warning if the current node isn't advertising any
subnet routes and isn't an exit node, since without one of those being
true, the node wouldn't have the correct AllowedIPs in WireGuard to
allow a Docker container to connect to another Tailscale node anyway.
Updates #12070
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Idef538695f4d101b0ef6f3fb398c0eaafc3ae281
Trying to run iptables/nftables on Synology pauses for minutes with
lots of errors and ultimately does nothing as it's not used and we
lack permissions.
This fixes a regression from db760d0bac (#11601) that landed
between Synology testing on unstable 1.63.110 and 1.64.0 being cut.
Fixes#11737
Change-Id: Iaf9563363b8e45319a9b6fe94c8d5ffaecc9ccef
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This removes a potentially increased boot delay for certain boot
topologies where they block on ExecStartPre that may have socket
activation dependencies on other system services (such as
systemd-resolved and NetworkManager).
Also rename cleanup to clean up in affected/immediately nearby places
per code review commentary.
Fixes#11599
Signed-off-by: James Tucker <james@tailscale.com>
Only on Gokrazy, set sysctls to enable IP forwarding so subnet routing
and advertised exit node works.
Fixes#11405
Signed-off-by: Joonas Kuorilehto <joneskoo@derbian.fi>
We have hosts that support IPv6, but not IPv6 firewall configuration
in iptables mode.
We also have hosts that have some support for IPv6 firewall
configuration in iptables mode, but do not have iptables filter table.
We should:
- configure ip rules for all hosts that support IPv6
- only configure firewall rules in iptables mode if the host
has iptables filter table.
Updates tailscale/tailscale#11540
Signed-off-by: Irbe Krumina <irbe@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>
* util/linuxfw, wgengine: allow ingress to magicsock UDP port on Linux
Updates #9084.
Currently, we have to tell users to manually open UDP ports on Linux when
certain firewalls (like ufw) are enabled. This change automates the process of
adding and updating those firewall rules as magicsock changes what port it
listens on.
Signed-off-by: Naman Sood <mail@nsood.in>
This will enable the runner to be replaced as a configuration side
effect in a later change.
Updates tailscale/corp#14029
Signed-off-by: James Tucker <james@tailscale.com>
Just a refactor to consolidate the firewall detection logic in a single
package so that it can be reused in a later commit by containerboot.
Updates #9310
Signed-off-by: Maisem Ali <maisem@tailscale.com>
Due to the conflict between our nftables implementation and ufw, which is a common utility used
on linux. We now want to take a step back to prevent regression. This will give us more chance to
let users to test our nftables support and heuristic.
Updates: #391
Signed-off-by: KevinLiang10 <kevinliang@tailscale.com>
To record wether user is using iptables or nftables after we add support to nftables on linux, we
are adding a field FirewallMode to NetInfo in HostInfo to reflect what firewall mode the host is
running, and form metrics. The information is gained from a global constant in hostinfo.go. We
set it when selection heuristic made the decision, and magicsock reports this to control.
Updates: tailscale/corp#13943
Signed-off-by: KevinLiang10 <kevinliang@tailscale.com>
The current router errors out when neither iptables nor nftables support is present. We
should fall back to the previous behaviour which we creates a dummy iptablesRunner.
Fixes: #8878
Signed-off-by: KevinLiang10 <kevinliang@tailscale.com>
This commit replaces the TS_DEBUG_USE_NETLINK_NFTABLES envknob with
a TS_DEBUG_FIREWALL_MODE that should be set to either 'iptables' or
'nftables' to select firewall mode manually, other wise tailscaled
will automatically choose between iptables and nftables depending on
environment and system availability.
updates: #319
Signed-off-by: KevinLiang10 <kevinliang@tailscale.com>
This commit adds nftable rule injection for tailscaled. If tailscaled is
started with envknob TS_DEBUG_USE_NETLINK_NFTABLES = true, the router
will use nftables to manage firewall rules.
Updates: #391
Signed-off-by: KevinLiang10 <kevinliang@tailscale.com>
This change is introducing new netfilterRunner interface and moving iptables manipulation to a lower leveled iptables runner.
For #391
Signed-off-by: KevinLiang10 <kevinliang@tailscale.com>
We're using it in more and more places, and it's not really specific to
our use of Wireguard (and does more just link/interface monitoring).
Also removes the separate interface we had for it in sockstats -- it's
a small enough package (we already pull in all of its dependencies
via other paths) that it's not worth the extra complexity.
Updates #7621
Updates #7850
Signed-off-by: Mihai Parparita <mihai@tailscale.com>
WSL has started to set the eth0 default route interface default to 1280
MTU, which is too low to carry 1280 byte packets from tailscale0 once
wrapped in WireGuard. The change down to 1280 is very likely smaller
than necessary for almost all users. We can not easily determine the
ideal MTU, but if all the preconditions match, we raise the MTU to 1360,
which is just enough for Tailscale traffic to work.
Updates #4833
Updates #7346
Signed-off-by: James Tucker <james@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 is temporary while we work to upstream performance work in
https://github.com/WireGuard/wireguard-go/pull/64. A replace directive
is less ideal as it breaks dependent code without duplication of the
directive.
Signed-off-by: Jordan Whited <jordan@tailscale.com>
Deleting may temporarily result in no addrs on the interface, which results in
all other rules (like routes) to get dropped by the OS.
I verified this fixes the problem.
Signed-off-by: Maisem Ali <maisem@tailscale.com>
Context: https://github.com/tailscale/tailscale/pull/5588#issuecomment-1260655929
It seems that if the interface at index 1 is down, the rule is not installed. As such,
we increase the range we detect up to 2004 in the hope that at least one of the interfaces
1-4 will be up.
Signed-off-by: Tom DNetto <tom@tailscale.com>
The io/ioutil package has been deprecated as of Go 1.16 [1]. This commit
replaces the existing io/ioutil functions with their new definitions in
io and os packages.
Reference: https://golang.org/doc/go1.16#ioutil
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
Mike O'Driscoll
Will Norris
Alex Chan
Sachin Iyer
M. J. Fromberger
Claus Lensbøl
Brad Fitzpatrick
David Anderson
Jason Barnett
Andrea Gottardo
Andrew Lytvynov
Andrew Dunham
James Tucker
Joonas Kuorilehto
Irbe Krumina
Naman Sood
Maisem Ali
KevinLiang10
Mihai Parparita
Jordan Whited
Josh Soref
Tom DNetto
Eng Zer Jun