tailscale

Commit Graph

Author	SHA1	Message	Date
Percy Wegmann	ecc451501c	ssh/tailssh: add ability to force V2 behavior using new feature flag Introduces ssh-behavior-v2 node attribute to override ssh-behavior-v1. Updates #11854 Signed-off-by: Percy Wegmann <percy@tailscale.com>	2 months ago
Percy Wegmann	4b525fdda0	ssh/tailssh: only chdir incubator process to user's homedir when necessary and possible Instead of changing the working directory before launching the incubator process, this now just changes the working directory after dropping privileges, at which point we're more likely to be able to enter the user's home directory since we're running as the user. For paths that use the 'login' or 'su -l' commands, those already take care of changing the working directory to the user's home directory. Fixes #13120 Signed-off-by: Percy Wegmann <percy@tailscale.com>	3 months ago
Percy Wegmann	7d83056a1b	ssh/tailssh: fix SSH on busybox systems This involved the following: 1. Pass the su command path as first of args in call to unix.Exec to make sure that busybox sees the correct program name. Busybox is a single executable userspace that implements various core userspace commands in a single binary. You'll see it used via symlinking, so that for example /bin/su symlinks to /bin/busybox. Busybox knows that you're trying to execute /bin/su because argv[0] is '/bin/su'. When we called unix.Exec, we weren't including the program name for argv[0], which caused busybox to fail with 'applet not found', meaning that it didn't know which command it was supposed to run. 2. Tell su to whitelist the SSH_AUTH_SOCK environment variable in order to support ssh agent forwarding. 3. Run integration tests on alpine, which uses busybox. 4. Increment CurrentCapabilityVersion to allow turning on SSH V2 behavior from control. Fixes #12849 Signed-off-by: Percy Wegmann <percy@tailscale.com>	3 months ago
Percy Wegmann	730f0368d0	ssh/tailssh: replace incubator process with su instead of running su as child This allows the SSH_AUTH_SOCK environment variable to work inside of su and agent forwarding to succeed. Fixes #12467 Signed-off-by: Percy Wegmann <percy@tailscale.com>	5 months ago
Percy Wegmann	d7fdc01f7f	ssh/tailssh: check IsSELinuxEnforcing in tailscaled process Checking in the incubator as this used to do fails because the getenforce command is not on the PATH. Updates #12442 Signed-off-by: Percy Wegmann <percy@tailscale.com>	5 months ago
Percy Wegmann	08a9551a73	ssh/tailssh: fall back to using su when no TTY available on Linux This allows pam authentication to run for ssh sessions, triggering automation like pam_mkhomedir. Updates #11854 Signed-off-by: Percy Wegmann <percy@tailscale.com>	6 months ago
Percy Wegmann	843afe7c53	ssh/tailssh: add integration test Updates tailscale/corp#11854 Signed-off-by: Percy Wegmann <percy@tailscale.com>	6 months ago
Brad Fitzpatrick	53c4adc982	ssh/tailssh: add envknobs to force override forwarding, sftp, pty Updates tailscale/corp#15735 Change-Id: Ib1303406be925c3231ce7e0950a173ad12626492 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>	1 year ago
Brad Fitzpatrick	58a4fd43d8	types/netmap, all: use read-only tailcfg.NodeView in NetworkMap Updates #8948 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>	1 year ago
Brad Fitzpatrick	e8551d6b40	all: use Go 1.21 slices, maps instead of x/exp/{slices,maps} Updates #8419 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>	1 year ago
Joe Tsai	bb4b35e923	ssh: ignore io.EOF from sftp.Server.Serve If the connection provided to sftp.NewServer is closed, Serve returns the io.EOF error verbatim from io.Reader.Read. This is an odd error since this is an expected situation, so we manually ignore io.EOF. This is somewhat buggy since the sftp package itself incorrectly reports io.EOF in cases where it should actually be reporting io.ErrUnexpectedEOF. See https://github.com/pkg/sftp/pull/554 which patches Serve to return nil on clean closes and fixes buggy uses of io.ReadFull. Fixes #8592 Signed-off-by: Joe Tsai <joetsai@digital-static.net>	1 year ago
Joe Tsai	61886e031e	ssh/tailssh: fix double race condition with non-pty command (#8405 ) There are two race conditions in output handling. The first race condition is due to a misuse of exec.Cmd.StdoutPipe. The documentation explicitly forbids concurrent use of StdoutPipe with exec.Cmd.Wait (see golang/go#60908) because Wait will close both sides of the pipe once the process ends without any guarantees that all data has been read from the pipe. To fix this, we allocate the os.Pipes ourselves and manage cleanup ourselves when the process has ended. The second race condition is because sshSession.run waits upon exec.Cmd to finish and then immediately proceeds to call ss.Exit, which will close all output streams going to the SSH client. This may interrupt any asynchronous io.Copy still copying data. To fix this, we close the write-side of the os.Pipes after the process has finished (and before calling ss.Exit) and synchronously wait for the io.Copy routines to finish. Fixes #7601 Signed-off-by: Joe Tsai <joetsai@digital-static.net> Co-authored-by: Maisem Ali <maisem@tailscale.com>	1 year ago
Brad Fitzpatrick	32b8f25ed1	Revert "ssh/tailssh: change to user directory when running login/command" This reverts commit `dc5bc32d8f`. It broke tests. (sadly, ones which we have disabled on CI, but go test ./ssh/tailssh broke)	1 year ago
Derek Burdick	dc5bc32d8f	ssh/tailssh: change to user directory when running login/command On redhat 9 and similarly locked down systems, root user does not have access to a users directory. This fix does not set a directory for the incubator process and instead sets the directory when the actual process requested by remote user is executed. Fixes #8118 Signed-off-by: Derek Burdick <derek-burdick@users.noreply.github.com>	1 year ago
Maisem Ali	2ae670eb71	ssh/tailssh: work around lack of scontext in SELinux Trying to SSH when SELinux is enforced results in errors like: ``` ➜ ~ ssh ec2-user@<ip> Last login: Thu Jun 1 22:51:44 from <ip2> ec2-user: no shell: Permission denied Connection to <ip> closed. ``` while the `/var/log/audit/audit.log` has ``` type=AVC msg=audit(1685661291.067:465): avc: denied { transition } for pid=5296 comm="login" path="/usr/bin/bash" dev="nvme0n1p1" ino=2564 scontext=system_u:system_r:unconfined_service_t:s0 tcontext=unconfined_u:unconfined_r:unconfined_t:s0 tclass=process permissive=0 ``` The right fix here would be to somehow install the appropriate context when tailscale is installed on host, but until we figure out a way to do that stop using the `login` cmd in these situations. Updates #4908 Signed-off-by: Maisem Ali <maisem@tailscale.com>	1 year ago
Maisem Ali	0ca8bf1e26	ssh/tailssh: close tty on session close We were only closing on side of the pty/tty pair. Close the other side too. Thanks to @fritterhoff for reporting and debugging the issue! Fixes #8119 Signed-off-by: Maisem Ali <maisem@tailscale.com>	2 years ago
Brad Fitzpatrick	a743b66f9d	ssh/tailssh: move some user-related code into new user.go The previous commit `58ab66e` added ssh/tailssh/user.go as part of working on #4945. So move some more user-related code over to it. Updates #cleanup Change-Id: I24de66df25ffb8f867e1a0a540d410f9ef16d7b0 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>	2 years ago
Brad Fitzpatrick	58ab66ec51	ssh/tailssh: support LDAP users for Tailscale SSH Fixes #4945 Change-Id: Ie013cb47684cb87928a44f92c66352310bfe53f1 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>	2 years ago
Andrew Dunham	280255acae	various: add golangci-lint, fix issues (#7905 ) This adds an initial and intentionally minimal configuration for golang-ci, fixes the issues reported, and adds a GitHub Action to check new pull requests against this linter configuration. Signed-off-by: Andrew Dunham <andrew@du.nham.ca> Change-Id: I8f38fbc315836a19a094d0d3e986758b9313f163	2 years ago
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>	2 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

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64 Commits (5f4a4c6744fbda767d5bf4b3299a16aea80c4d1c)