Commit Graph

45 Commits (e5d272f445916b80a65175bfb283d8c56f8e2b39)

Author SHA1 Message Date
Brad Fitzpatrick 2c0bda6e2e ssh/tailssh: make Tailscale SSH work on gokrazy
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 years ago
Andrew Dunham 13377e6458 ssh/tailssh: always assert our final uid/gid
Move the assertions about our post-privilege-drop UID/GID out of the
conditional if statement and always run them; I haven't been able to
find a case where this would fail. Defensively add an envknob to disable
this feature, however, which we can remove after the 1.40 release.

Updates #7616

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Iaec3dba9248131920204bd6c6d34bbc57a148185
2 years ago
Andrew Dunham 9de8287d47 ssh/tailssh: lock OS thread during incubator
This makes it less likely that we trip over bugs like golang/go#1435.

Updates #7616

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ic28c03c3ad8ed5274a795c766b767fa876029f0e
2 years ago
Andrew Dunham 39b289578e ssh/tailssh: make uid an int instead of uint64
Follow-up to #7615

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ib4256bff276f6d5cf95838d8e39c87b3643bde37
2 years ago
Andrew Dunham ccace1f7df ssh/tailssh: fix privilege dropping on FreeBSD; add tests
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
2 years ago
Maisem Ali 223713d4a1 tailcfg,all: add and use Node.IsTagged()
Signed-off-by: Maisem Ali <maisem@tailscale.com>
2 years ago
Maisem Ali 0582829e00 ssh/tailssh: try launching commands with /usr/bin/login on macOS
Updates #4939

Co-authored-by: Adam Eijdenberg <adam@continusec.com>
Signed-off-by: Maisem Ali <maisem@tailscale.com>
2 years ago
Maisem Ali 5787989d74 ssh/tailssh: detect user shell correctly on darwin
Updates #6213

Signed-off-by: Maisem Ali <maisem@tailscale.com>
2 years ago
Brad Fitzpatrick b1248442c3 all: update to Go 1.20, use strings.CutPrefix/Suffix instead of our fork
Updates #7123
Updates #5309

Change-Id: I90bcd87a2fb85a91834a0dd4be6e03db08438672
Signed-off-by: Brad Fitzpatrick <bradfitz@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>
2 years ago
Brad Fitzpatrick 1116602d4c ssh/tailssh: add OpenBSD support for Tailscale SSH
And bump go.mod for https://github.com/u-root/u-root/pull/2593

Change-Id: I36ec94c5b2b76d671cb739f1e9a1a43ca1d9d1b1
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 years ago
Brad Fitzpatrick be67b8e75b ssh/tailssh: fix Tailscale SSH to non-root tailscaled
Fix regression from 337c77964b where
tailscaled started calling Setgroups. Prior to that, SSH to a non-root
tailscaled was working.

Instead, ignore any failure calling Setgroups if the groups are
already correct.

Fixes #6888

Change-Id: I561991ddb37eaf2620759c6bcaabd36e0fb2a22d
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 years ago
Brad Fitzpatrick 8047dfa2dc ssh/tailssh: unify some of the incubator_* GOOS files into incubator.go
In prep for fix for #6888

Change-Id: I79f780c6467a9b7ac03017b27d412d6b0d2f7e6b
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 years ago
Brad Fitzpatrick 84eaef0bbb ssh/tailssh: don't swallow process exit code in be-child
Thanks to @nshalman and @Soypete for debugging!

Updates #6054

Change-Id: I74550cc31f8a257b37351b8152634c768e1e0a8a
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 years ago
Brad Fitzpatrick 651e0d8aad ssh/tailssh: add envknob for default PATH
As backup plan, just in case the earlier fix's logic wasn't correct
and we want to experiment in the field or have users have a quicker
fix.

Updates #5285

Change-Id: I7447466374d11f8f609de6dfbc4d9a944770826d
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 years ago
Brad Fitzpatrick 56f7da0cfd
ssh/tailssh: set default Tailscale SSH $PATH for non-interactive commands
Fixes #5285

Co-authored-by: Andrew Dunham <andrew@tailscale.com>
Change-Id: Ic7e967bf6a53b056cac5f21dd39565d9c31563af
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 years ago
Pat Maddox 9bf3ef4167 ssh/tailssh: add Tailscale SSH (server) support on FreeBSD
Change-Id: I607194b6ef99205e777f3df93a74ffe1a2e0344c
Signed-off-by: Pat Maddox <pat@ratiopbc.com>
2 years ago
Brad Fitzpatrick da8def8e13 all: remove old +build tags
The //go:build syntax was introduced in Go 1.17:

https://go.dev/doc/go1.17#build-lines

gofmt has kept the +build and go:build lines in sync since
then, but enough time has passed. Time to remove them.

Done with:

    perl -i -npe 's,^// \+build.*\n,,' $(git grep -l -F '+build')

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2 years ago
Maisem Ali 1440742a1c ssh/tailssh: use root / as cmd.Dir when users HomeDir doesn't exist
Fixes #5224

Signed-off-by: Maisem Ali <maisem@tailscale.com>
2 years ago
Maisem Ali f16b77de5d ssh/tailssh: do the full auth flow during ssh auth
Fixes #5091

Signed-off-by: Maisem Ali <maisem@tailscale.com>
2 years ago
Josh Soref d4811f11a0 all: fix spelling mistakes
Signed-off-by: Josh Soref <2119212+jsoref@users.noreply.github.com>
2 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>
2 years ago
Maisem Ali 480fd6c797 ssh/tailssh: handle not-authenticated-yet connections in matchRule
Also make more fields in conn.info thread safe, there was previously a
data race here.

Fixes #5110

Signed-off-by: Maisem Ali <maisem@tailscale.com>
2 years ago
Maisem Ali af412e8874 ssh/tailssh: better handling of signals and exits
We were not handling errors occurred while copying data between the subprocess and the connection.
This makes it so that we pass the appropriate signals when to the process and the connection.

This also fixes mosh.

Updates #4919

Co-authored-by: James Tucker <raggi@tailscale.com>
Co-authored-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Signed-off-by: Maisem Ali <maisem@tailscale.com>
2 years ago
Adam Eijdenberg 9294a14a37 ssh/tailssh: limit setgroups to 16 on macOS
Fixes #4938

Signed-off-by: Adam Eijdenberg <adam@continusec.com>
2 years ago
Adam Eijdenberg 7f807fef6c ssh/tailssh: fix /usr/bin/login args on macOS
Fixes #4931

Signed-off-by: Adam Eijdenberg <adam@continusec.com>
2 years ago
Maisem Ali 760740905e ssh/tailssh: only use `login` with TTY sessions
Otherwise, the shell exits immediately causing applications like mosh
and VSCode to fail.

Signed-off-by: Maisem Ali <maisem@tailscale.com>
3 years ago
Maisem Ali 5cd56fe8d5 ssh/tailssh: exec into `login` when launching a shell
This has the added benefit of displaying the MOTD and reducing our
dependency on the DBus interface.

Fixes #4627
Updates #3802

Signed-off-by: Maisem Ali <maisem@tailscale.com>
3 years ago
Maisem Ali a253057fc3 ssh/tailssh: refactor incubator flags
Signed-off-by: Maisem Ali <maisem@tailscale.com>
3 years ago
David Anderson a364bf2b62 ssh/tailssh: various typo fixes, clarifications.
Signed-off-by: David Anderson <danderson@tailscale.com>
3 years ago
Maisem Ali 337c77964b ssh/tailssh: set groups and gid in the incubated process
Updates #3802

Signed-off-by: Maisem Ali <maisem@tailscale.com>
3 years ago
Brad Fitzpatrick 8ac4d52b59 ssh/tailssh: filter accepted environment variables
Noted by @danderson

Updates #3802

Change-Id: Iac70717ed57f11726209ac1ea93ddc6696605f94
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Maisem Ali 695f8a1d7e ssh/tailssh: add support for sftp
Updates #3802

Signed-off-by: Maisem Ali <maisem@tailscale.com>
3 years ago
Maisem Ali 2b8b887d55 ssh/tailssh: send banner messages during auth, move more to conn
(VSCode Live Share between Brad & Maisem!)

Updates #3802

Change-Id: Id8edca4481b0811debfdf56d4ccb1a46f71dd6d3
Co-Authored-By: Brad Fitzpatrick <bradfitz@tailscale.com>
Signed-off-by: Maisem Ali <maisem@tailscale.com>
3 years ago
Brad Fitzpatrick da14e024a8 tailcfg, ssh/tailssh: optionally support SSH public keys in wire policy
And clean up logging.

Updates #3802

Change-Id: I756dc2d579a16757537142283d791f1d0319f4f0
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick 5a44f9f5b5 tempfork: temporarily fork gliderlabs/ssh and x/crypto/ssh
While we rearrange/upstream things.

gliderlabs/ssh is forked into tempfork from our prior fork
at be8b7add40

x/crypto/ssh OTOH is forked at
https://github.com/tailscale/golang-x-crypto because it was gnarlier
to vendor with various internal packages, etc.
Its git history shows where it starts (2c7772ba30643b7a2026cbea938420dce7c6384d).

Updates #3802

Change-Id: I546e5cdf831cfc030a6c42557c0ad2c58766c65f
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Maisem Ali 98b45ef12c ssh/tailssh: add support for agent forwarding.
Updates #3802

Signed-off-by: Maisem Ali <maisem@tailscale.com>
3 years ago
Brad Fitzpatrick 6e86bbcb06 ssh/tailssh: add a new sshSession type to clean up existing+future code
Updates #3802

Change-Id: I7054dca387f5e5aee1185937ecf41b77a5a07f1a
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Co-authored-by: Maisem Ali <maisem@tailscale.com>
3 years ago
Maisem Ali bf3559171f ssh/tailssh: set DBUS_SESSION_BUS_ADDRESS and SSH_TTY variables
Updates #3802

Signed-off-by: Maisem Ali <maisem@tailscale.com>
3 years ago
Maisem Ali 6d61b7906e ssh/tailssh: handle terminal opcodes
Updates #3802 #4146

Signed-off-by: Maisem Ali <maisem@tailscale.com>
3 years ago
Maisem Ali da6ce27416 go.mod: move from github.com/gliderlabs/ssh to github.com/tailscale/ssh
Updates #4146

Signed-off-by: Maisem Ali <maisem@tailscale.com>
3 years ago
Brad Fitzpatrick ba1adf6c24 ssh/tailssh: make pty termios options match OpenSSH
Still not sure the exact rules of how/when/who's supposed to set
these, but this works for now on making them match. Baby steps.
Will research more and adjust later.

Updates #4146 (but not enough to fix it, something's still wrong)
Updates #3802

Change-Id: I496d8cd7e31d45fe9ede88fc8894f35dc096de67
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Brad Fitzpatrick 1dd5cf62a5 ssh/tailssh: start login shell, fix arg passing, width/height mismatch
Updates #3802

Change-Id: I137d7a79195ee86d5dd7c8999f2797fc3cb57cec
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
3 years ago
Maisem Ali 598c7a22e7 ssh/tailssh: use lu.Username not lu.Name.
Signed-off-by: Maisem Ali <maisem@tailscale.com>
3 years ago
Maisem Ali 06c147d848 ssh/tailssh: create login sessions for new connections
Signed-off-by: Maisem Ali <maisem@tailscale.com>
3 years ago