Commit Graph

54 Commits (8085324449c133adf6214f07845df62cac970b30)

Author SHA1 Message Date
Claus Lensbøl 8085324449
net/dns: retrample resolve.conf when another process has trampled it
When using the resolve.conf file for setting DNS, it is possible that
some other services will trample the file and overwrite our set DNS
server. Experiments has shown this to be a racy error depending on how
quickly processes start.

Make an attempt to trample back the file a limited number of times if
the file is changed.

Updates #16635

Signed-off-by: Claus Lensbøl <claus@tailscale.com>
2 days ago
Brad Fitzpatrick bcd79b161a feature/featuretags: add option to turn off DNS
Saves 328 KB (2.5%) off the minimal binary.

For IoT devices that don't need MagicDNS (e.g. they don't make
outbound connections), this provides a knob to disable all the DNS
functionality.

Rather than a massive refactor today, this uses constant false values
as a deadcode sledgehammer, guided by shotizam to find the largest DNS
functions which survived deadcode.

A future refactor could make it so that the net/dns/resolver and
publicdns packages don't even show up in the import graph (along with
their imports) but really it's already pretty good looking with just
these consts, so it's not at the top of my list to refactor it more
soon.

Also do the same in a few places with the ACME (cert) functionality,
as I saw those while searching for DNS stuff.

Updates #12614

Change-Id: I8e459f595c2fde68ca16503ff61c8ab339871f97
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 months ago
Brad Fitzpatrick b3e9a128af net/dns, feature/featuretags: make NetworkManager, systemd-resolved, and DBus modular
Saves 360 KB (19951800 => 19591352 on linux/amd64 --extra-small --box binary)

Updates #12614
Updates #17206

Change-Id: Iafd5b2536dd735111b447546cba335a7a64379ed
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 months ago
Brad Fitzpatrick 2b3e533048 util/syspolicy: finish plumbing policyclient, add feature/syspolicy, move global impl
This is step 4 of making syspolicy a build-time feature.

This adds a policyclient.Get() accessor to return the correct
implementation to use: either the real one, or the no-op one. (A third
type, a static one for testing, also exists, so in general a
policyclient.Client should be plumbed around and not always fetched
via policyclient.Get whenever possible, especially if tests need to use
alternate syspolicy)

Updates #16998
Updates #12614

Change-Id: Iaf19670744a596d5918acfa744f5db4564272978
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 months ago
Brad Fitzpatrick fbc6a9ec5a all: detect JetKVM and specialize a handful of things for it
Updates #16524

Change-Id: I183428de8c65d7155d82979d2d33f031c22e3331
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
5 months ago
Brad Fitzpatrick 02f68e5d9f net/dns: don't link dbus, gonotify on Android
Android is Linux, but doesn't use Linux DNS managers (or D-Bus).

Updates #12614

Change-Id: I487802ac74a259cd5d2480ac26f7faa17ca8d1c3
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
7 months ago
Nick Khyl c32efd9118 various: create a catch-all NRPT rule when "Override local DNS" is enabled on Windows
Without this rule, Windows 8.1 and newer devices issue parallel DNS requests to DNS servers
associated with all network adapters, even when "Override local DNS" is enabled and/or
a Mullvad exit node is being used, resulting in DNS leaks.

This also adds "disable-local-dns-override-via-nrpt" nodeAttr that can be used to disable
the new behavior if needed.

Fixes tailscale/corp#20718

Signed-off-by: Nick Khyl <nickk@tailscale.com>
1 year ago
Brad Fitzpatrick 745931415c health, all: remove health.Global, finish plumbing health.Tracker
Updates #11874
Updates #4136

Change-Id: I414470f71d90be9889d44c3afd53956d9f26cd61
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 years ago
Brad Fitzpatrick ebc552d2e0 health: add Tracker type, in prep for removing global variables
This moves most of the health package global variables to a new
`health.Tracker` type.

But then rather than plumbing the Tracker in tsd.System everywhere,
this only goes halfway and makes one new global Tracker
(`health.Global`) that all the existing callers now use.

A future change will eliminate that global.

Updates #11874
Updates #4136

Change-Id: I6ee27e0b2e35f68cb38fecdb3b2dc4c3f2e09d68
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 years ago
Andrew Dunham b0e96a6c39 net/dns: log more info when openresolv commands fail
Updates #11129

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ic594868ba3bc31f6d3b0721ecba4090749a81f7f
2 years ago
Andrew Lytvynov 2716250ee8
all: cleanup unused code, part 2 (#10670)
And enable U1000 check in staticcheck.

Updates #cleanup

Signed-off-by: Andrew Lytvynov <awly@tailscale.com>
2 years ago
Denton Gentry 97ee3891f1 net/dns: use direct when NetworkManager has no systemd-resolved
Endeavour OS, at least, uses NetworkManager 1.44.2 and does
not use systemd-resolved behind the scenes at all. If we
find ourselves in that situation, return "direct" not
"systemd-resolved"

Fixes https://github.com/tailscale/tailscale/issues/9687

Signed-off-by: Denton Gentry <dgentry@tailscale.com>
2 years ago
Anton Tolchanov 388b124513 net/dns: detect when libnss_resolve is used
Having `127.0.0.53` is not the only way to use `systemd-resolved`. An
alternative way is to enable `libnss_resolve` module, which seems to now
be used by default on Debian 12 bookworm.

Fixes #8549

Signed-off-by: Anton Tolchanov <anton@tailscale.com>
2 years ago
Will Norris 71029cea2d all: update copyright and license headers
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>
3 years ago
Maisem Ali 99aa335923 net/dns: [linux] log and add metric for dnsMode
I couldn't find any logs that indicated which mode it was running in so adding that.
Also added a gauge metric for dnsMode.

Signed-off-by: Maisem Ali <maisem@tailscale.com>
3 years ago
Andrew Dunham e966f024b0 net/dns: print systemd-resolved ResolvConfMode
The ResolvConfMode property is documented to return how systemd-resolved
is currently managing /etc/resolv.conf. Include that information in the
debug line, when available, to assist in debugging DNS issues.

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I1ae3a257df1d318d0193a8c7f135c458ec45093e
3 years ago
nyghtowl e6e1976c3a net/dns: remove systemd-resolved ping
Ping only needed to ensure system awak otherwise utilizing resolvConf to set dns mode.

Signed-off-by: nyghtowl <warrick@tailscale.com>
3 years ago
Brad Fitzpatrick 7eaf5e509f net/netaddr: start migrating to net/netip via new netaddr adapter package
Updates #5162

Change-Id: Id7bdec303b25471f69d542f8ce43805328d56c12
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick 2ff481ff10 net/dns: add health check for particular broken-ish Linux DNS config
Updates #3937 (need to write docs before closing)

Change-Id: I1df7244cfbb0303481e2621ee750d21358bd67c6
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
4 years ago
Brad Fitzpatrick 21358cf2f5 net/dns: slightly optimize dbusPing for non-dbus case [Linux]
Avoid some work when D-Bus isn't running.

Change-Id: I6f89bb75fdb24c13f61be9b400610772756db1ef
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
4 years ago
Brad Fitzpatrick 15599323a1 net/dns: fix systemd-resolved detection race at boot
If systemd-resolved is enabled but not running (or not yet running,
such as early boot) and resolv.conf is old/dangling, we weren't
detecting systemd-resolved.

This moves its ping earlier, which will trigger it to start up and
write its file.

Updates #3362 (likely fixes)
Updates #3531 (likely fixes)

Change-Id: I6392944ac59f600571c43b8f7a677df224f2beed
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
4 years ago
Brad Fitzpatrick 6feb8f4c51 net/dns: log why resolved does not look like it's on use [Linux]
Updates #3742
Updates #3531

Change-Id: I9fc7fa0f4bcab1cf8001ba92408c660a5b25f105
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
4 years ago
David Anderson c5d572f371 net/dns: correctly handle NetworkManager-managed DNS that points to resolved.
Fixes #3304

Signed-off-by: David Anderson <danderson@tailscale.com>
4 years ago
David Anderson a320d70614 net/dns: fall back to copy+delete/truncate if moving to/from /etc/resolv.conf fails.
In some containers, /etc/resolv.conf is a bind-mount from outside the container.
This prevents renaming to or from /etc/resolv.conf, because it's on a different
filesystem from linux's perspective. It also prevents removing /etc/resolv.conf,
because doing so would break the bind-mount.

If we find ourselves within this environment, fall back to using copy+delete when
renaming to /etc/resolv.conf, and copy+truncate when renaming from /etc/resolv.conf.

Fixes #3000

Co-authored-by: Denton Gentry <dgentry@tailscale.com>
Signed-off-by: David Anderson <danderson@tailscale.com>
4 years ago
David Anderson 10547d989d net/dns: exhaustively test DNS selection paths for linux.
Signed-off-by: David Anderson <danderson@tailscale.com>
4 years ago
David Anderson c071bcda33 net/dns: relax systemd-resolved detection.
Reported on IRC: a resolv.conf that contained two entries for
"nameserver 127.0.0.53", which defeated our "is resolved actually
in charge" check. Relax that check to allow any number of nameservers,
as long as they're all 127.0.0.53.

Signed-off-by: David Anderson <danderson@tailscale.com>
4 years ago
Brad Fitzpatrick 065c4ffc2c net/dns: add start of Linux newOSConfigurator tests
Only one test case so far.

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
4 years ago
Brad Fitzpatrick 09a47ea3f1 net/dns: prep for writing manager_linux tests; pull some stuff out
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
4 years ago
David Crawshaw 9b063b86c3 net/dns: factor directManager out over an FS interface
This is preliminary work for using the directManager as
part of a wslManager on windows, where in addition to configuring
windows we'll use wsl.exe to edit the linux file system and modify the
system resolv.conf.

The pinholeFS is a little funky, but it's designed to work through
simple unix tools via wsl.exe without invoking bash. I would not have
thought it would stand on its own like this, but it turns out it's
useful for writing a test for the directManager.

Signed-off-by: David Crawshaw <crawshaw@tailscale.com>
4 years ago
David Anderson 9337826011 net/dns: fix inverted test for NetworkManager version.
Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson 320cc8fa21 net/dns: verify that systemd-resolved is actually in charge.
It's possible to install a configuration that passes our current checks
for systemd-resolved, without actually pointing to systemd-resolved. In
that case, we end up programming DNS in resolved, but that config never
applies to any name resolution requests on the system.

This is quite a far-out edge case, but there's a simple additional check
we can do: if the header comment names systemd-resolved, there should be
a single nameserver in resolv.conf pointing to 127.0.0.53. If not, the
configuration should be treated as an unmanaged resolv.conf.

Fixes #2136.

Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson e7164425b3 net/dns: don't use NetworkManager for DNS on very old NetworkManagers.
Fixes #1945.

Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
Dave Anderson 144c68b80b
net/dns: avoid using NetworkManager as much as possible. (#1945)
Addresses #1699 as best as possible.

Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson cfde997699 net/dns: don't use interfaces.Tailscale to find the tailscale interface index.
interfaces.Tailscale only returns an interface if it has at least one Tailscale
IP assigned to it. In the resolved DNS manager, when we're called upon to tear
down DNS config, the interface no longer has IPs.

Instead, look up the interface index on construction and reuse it throughout
the daemon lifecycle.

Fixes #1892.

Signed-off-by: David Anderson <dave@natulte.net>
5 years ago
David Anderson f6b7d08aea net/dns: work around new NetworkManager in other selection paths.
Further bits of #1788

Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson 25ce9885a2 net/dns: don't use NM+resolved for NM >=1.26.6.
NetworkManager fixed the bug that forced us to use NetworkManager
if it's programming systemd-resolved, and in the same release also
made NetworkManager ignore DNS settings provided for unmanaged
interfaces... Which breaks what we used to do. So, with versions
1.26.6 and above, we MUST NOT use NetworkManager to indirectly
program systemd-resolved, but thankfully we can talk to resolved
directly and get the right outcome.

Fixes #1788

Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson bb0710d51d net/dns: add debugging traces to DNS manager selection on linux.
Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson 4b70c7b717 net/dns: fix inverted test for NetworkManager.
Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson 4849a4d3c8 net/dns: error out on linux if /etc/resolv.conf can't be read.
Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson 1f9b73a531 net/dns: fix freebsd DNS manager selection.
Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson d6bb11b5bf net/dns: implement correct manager detection on linux.
Part of #953.

Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson 854d5d36a1 net/dns: return error from NewOSManager, use it to initialize NM.
Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson cca230cc23 net/dns: fix staticcheck errors.
Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson a7340c2015 net/dns: support split DNS in systemd-resolved.
Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson 84430cdfa1 net/dns: improve NetworkManager detection, using more DBus.
Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson 9a48bac8ad net/dns: rename resolvconf.go to debian_resolvconf.go.
Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson 58760f7b82 net/dns: split resolvconfManager into a debian and an openresolv manager.
Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson 4c61ebacf4 wgengine: move DNS configuration out of wgengine/router.
Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson a39d2403bc net/dns: disable NetworkManager and resolved configurators temporarily.
They need some rework to do the right thing, in the meantime the direct
and resolvconf managers will work out.

The resolved implementation was never selected due to control-side settings.
The networkmanager implementation mostly doesn't get selected due to
unforeseen interactions with `resolvconf` on many platforms.
Both implementations also need rework to support the various routing modes
they're capable of.

Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago
David Anderson befd8e4e68 net/dns: replace managerImpl with OSConfigurator in code.
Signed-off-by: David Anderson <danderson@tailscale.com>
5 years ago