On FreeBSD and Darwin, changing a process's supplementary groups with
setgroups(2) will also change the egid of the process, setting it to the
first entry in the provided list. This is distinct from the behaviour on
other platforms (and possibly a violation of the POSIX standard).
Because of this, on FreeBSD with no TTY, our incubator code would
previously not change the process's gid, because it would read the
newly-changed egid, compare it against the expected egid, and since they
matched, not change the gid. Because we didn't use the 'login' program
on FreeBSD without a TTY, this would propagate to a child process.
This could be observed by running "id -p" in two contexts. The expected
output, and the output returned when running from a SSH shell, is:
andrew@freebsd:~ $ id -p
uid andrew
groups andrew
However, when run via "ssh andrew@freebsd id -p", the output would be:
$ ssh andrew@freebsd id -p
login root
uid andrew
rgid wheel
groups andrew
(this could also be observed via "id -g -r" to print just the gid)
We fix this by pulling the details of privilege dropping out into their
own function and prepending the expected gid to the start of the list on
Darwin and FreeBSD.
Finally, we add some tests that run a child process, drop privileges,
and assert that the final UID/GID/additional groups are what we expect.
More information can be found in the following article:
https://www.usenix.org/system/files/login/articles/325-tsafrir.pdf
Updates #7616
Alternative to #7609
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I0e6513c31b121108b50fe561c89e5816d84a45b9
This allows tracking packet flow via logs for prober clients. Note that
the new sclient.debug() function is called on every received packet, but
will do nothing for most clients.
I have adjusted sclient logging to print public keys in short format
rather than full. This takes effect even for existing non-debug logging
(mostly client disconnect messages).
Example logs for a packet being sent from client [SbsJn] (connected to
derper [dM2E3]) to client [10WOo] (connected to derper [AVxvv]):
```
derper [dM2E3]:
derp client 10.0.0.1:35470[SbsJn]: register single client mesh("10.0.1.1"): 4 peers
derp client 10.0.0.1:35470[SbsJn]: read frame type 4 len 40 err <nil>
derp client 10.0.0.1:35470[SbsJn]: SendPacket for [10WOo], forwarding via <derphttp_client.Client [AVxvv] url=https://10.0.1.1/derp>: <nil>
derp client 10.0.0.1:35470[SbsJn]: read frame type 0 len 0 err EOF
derp client 10.0.0.1:35470[SbsJn]: read EOF
derp client 10.0.0.1:35470[SbsJn]: sender failed: context canceled
derp client 10.0.0.1:35470[SbsJn]: removing connection
derper [AVxvv]:
derp client 10.0.1.1:50650[10WOo]: register single client
derp client 10.0.1.1:50650[10WOo]: received forwarded packet from [SbsJn] via [dM2E3]
derp client 10.0.1.1:50650[10WOo]: sendPkt attempt 0 enqueued
derp client 10.0.1.1:50650[10WOo]: sendPacket from [SbsJn]: <nil>
derp client 10.0.1.1:50650[10WOo]: read frame type 0 len 0 err EOF
derp client 10.0.1.1:50650[10WOo]: read EOF
derp client 10.0.1.1:50650[10WOo]: sender failed: context canceled
derp client 10.0.1.1:50650[10WOo]: removing connection
```
Signed-off-by: Anton Tolchanov <anton@tailscale.com>
This allows disabling spread mode, which is helpful if you are manually
running derpprobe in `--once` mode against a small number of DERP
machines.
Updates https://github.com/tailscale/corp/issues/9916
Signed-off-by: Anton Tolchanov <anton@tailscale.com>
Xcode changed how/what data it exports to build steps at some point
recently, so our old way of figuring out the minimum support version
for clang stopped working.
Updates tailscale/corp#4095
Signed-off-by: David Anderson <danderson@tailscale.com>
Sometimes, our cached toolchain ends up being an older version of
Go, older than our go.mod allows. In that scenario, gocross-wrapper.sh
would find a usable toolchain, but then fail to compile gocross.
This change makes the wrapper script check that the cached toolchain's
minor version is good enough to build tailscale.com, and re-bootstraps
in shell if not.
Signed-off-by: David Anderson <danderson@tailscale.com>
They're not needed for the sockstats logger, and they're somewhat
expensive to return (since they involve the creation of a map per
label). We now have a separate GetInterfaces() method that returns
them instead (which we can still use in the PeerAPI debug endpoint).
If changing sockstatlog to sample at 10,000 Hz (instead of the default
of 10Hz), the CPU usage would go up to 59% on a iPhone XS. Removing the
per-interface stats drops it to 20% (a no-op implementation of Get that
returns a fixed value is 16%).
Updates tailscale/corp#9230
Updates #3363
Signed-off-by: Mihai Parparita <mihai@tailscale.com>
I thought our versioning scheme would make go.mod include a commit hash
even on stable builds. I was wrong. Fortunately, the rest of this code
wants anything that 'git rev-parse' understands (to convert it into a full
git hash), and tags qualify.
Signed-off-by: David Anderson <danderson@tailscale.com>
tsnet.Server.Close was calling listener.Close with the server mutex
held, but the listener close method tries to grab that mutex, resulting
in a deadlock.
Co-authored-by: David Crawshaw <crawshaw@tailscale.com>
Signed-off-by: Maisem Ali <maisem@tailscale.com>
We were not handling tags at all, pass them through as Impersonate-Group headers.
And use the FQDN for tagged nodes as Impersonate-User.
Updates #5055
Signed-off-by: Maisem Ali <maisem@tailscale.com>
We persist the ServeConfig, even for tsnet apps. It's quite possible for
the ServeConfig to be out of step with the code. Example: If you run
`ListenFunnel` then later turn it off, the ServeConfig will still show
it enabled, the admin console will show it enabled, but the packet
handler will reject the packets.
Workaround by clearing the ServeConfig in `tsnet.Up`
Signed-off-by: Shayne Sweeney <shayne@tailscale.com>
This lets a tsnet binary share a server out over Tailscale Funnel.
Signed-off-by: David Crawshaw <crawshaw@tailscale.com>
Signed-off-by: Maisem Ali <maisem@tailscale.com>
Signed-off-by: Shayne Sweeney <shayne@tailscale.com>
Followup to #7499 to make validation a separate function (
GetWithValidation vs. Get). This way callers that don't need it don't
pay the cost of a syscall per active TCP socket.
Also clears the conn on close, so that we don't double-count the stats.
Also more consistently uses Go doc comments for the exported API of the
sockstats package.
Updates tailscale/corp#9230
Updates #3363
Signed-off-by: Mihai Parparita <mihai@tailscale.com>
Though not fine-grained enough to be useful for detailed analysis, we
might as well export that we gather as client metrics too, since we have
an upload/analysis pipeline for them.
clientmetric.Metric.Add is an atomic add, so it's pretty cheap to also
do per-packet.
Updates tailscale/corp#9230
Updates #3363
Signed-off-by: Mihai Parparita <mihai@tailscale.com>
Previously the part that handled Funnel connections was not
aware of any listeners that tsnet.Servers might have had open
so it would check against the ServeConfig and fail.
Adding a ServeConfig for a TCP proxy was also not suitable in this
scenario as that would mean creating two different listeners and have
one forward to the other, which really meant that you could not have
funnel and tailnet-only listeners on the same port.
This also introduces the ipn.FunnelConn as a way for users to identify
whether the call is coming over funnel or not. Currently it only holds
the underlying conn and the target as presented in the "Tailscale-Ingress-Target"
header.
Signed-off-by: Maisem Ali <maisem@tailscale.com>
The addition of WaitGroup.Go in the standard library has been
repeatedly proposed and rejected.
See golang/go#18022, golang/go#23538, and golang/go#39863
In summary, the argument for WaitGroup.Go is that it avoids bugs like:
go func() {
wg.Add(1)
defer wg.Done()
...
}()
where the increment happens after execution (not before)
and also (to a lesser degree) because:
wg.Go(func() {
...
})
is shorter and more readble.
The argument against WaitGroup.Go is that the provided function
takes no arguments and so inputs and outputs must closed over
by the provided function. The most common race bug for goroutines
is that the caller forgot to capture the loop iteration variable,
so this pattern may make it easier to be accidentally racy.
However, that is changing with golang/go#57969.
In my experience the probability of race bugs due to the former
still outwighs the latter, but I have no concrete evidence to prove it.
The existence of errgroup.Group.Go and frequent utility of the method
at least proves that this is a workable pattern and
the possibility of accidental races do not appear to
manifest as frequently as feared.
A reason *not* to use errgroup.Group everywhere is that there are many
situations where it doesn't make sense for the goroutine to return an error
since the error is handled in a different mechanism
(e.g., logged and ignored, formatted and printed to the frontend, etc.).
While you can use errgroup.Group by always returning nil,
the fact that you *can* return nil makes it easy to accidentally return
an error when nothing is checking the return of group.Wait.
This is not a hypothetical problem, but something that has bitten us
in usages that was only using errgroup.Group without intending to use
the error reporting part of it.
Thus, add a (yet another) variant of WaitGroup here that
is identical to sync.WaitGroup, but with an extra method.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
This reverts commit 6eca47b16c and fixes forward.
Previously the first ever streaming MapRequest that a client sent would also
set ReadOnly to true as it didn't have any endpoints and expected/relied on the
map poll to restart as soon as it got endpoints. However with 48f6c1eba4,
we would no longer restart MapRequests as frequently as we used to, so control
would only ever get the first streaming MapRequest which had ReadOnly=true.
Control would treat this as an uninteresting request and would not send it
any further netmaps, while the client would happily stay in the map poll forever
while litemap updates happened in parallel.
This makes it so that we never set `ReadOnly=true` when we are doing a streaming
MapRequest. This is no longer necessary either as most endpoint discovery happens
over disco anyway.
Co-authored-by: Andrew Dunham <andrew@du.nham.ca>
Signed-off-by: Maisem Ali <maisem@tailscale.com>
Add Value, which measures the rate at which an event occurs,
exponentially weighted towards recent activity.
It is guaranteed to occupy O(1) memory, operate in O(1) runtime,
and is safe for concurrent use.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
