X11 forwarding fails without /tmp/.X11-unix directory

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3 participants
  • Ludovic Courtès
  • Maxim Cournoyer
  • myglc2
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unassigned
Submitted by
myglc2
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normal
Merged with
M
M
myglc2 wrote on 7 Mar 2016 02:10
(address . bug-guix@gnu.org)
87twkj6qk6.fsf@gmail.com
Example: using guix commit 59a4dd5 with openssh xauth & emacs in the
user profile (c02glc.scm) and a minimal system profile (c02system.scm),
after a reboot we see ...

nemo:~ $ ssh g1
glc@g1's password:
X11 forwarding request failed on channel 0

... and in /var/log/messages ...

Mar 6 19:23:35 localhost lshd[372]: lshd: Failed to cd to `/tmp/.X11-unix' (errno = 2): No such file or directory
Mar 6 19:23:35 localhost lshd[372]: lshd: Updating utmp for login failed (errno = 2): No such file or directory

If we do ...

mkdir /tmp/.X11-unix

... logout and login, forwarding works, emacs runs in X, and
/var/log/messages is clean. If we reboot, X11 forwarding again fails.
Attachment: c02glc.scm
Attachment: c02system.scm
L
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Ludovic Courtès wrote on 1 Aug 2016 11:52
control message for bug #23960
(address . control@debbugs.gnu.org)
87d1lsu87o.fsf@gnu.org
merge 23960 22930
L
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Ludovic Courtès wrote on 1 Aug 2016 11:53
control message for bug #24049
(address . control@debbugs.gnu.org)
87bn1cu876.fsf@gnu.org
merge 24049 22930
M
M
Maxim Cournoyer wrote on 6 Oct 2020 06:04
Re: bug#24049: GuixSD - problem with X11 forwarding
(name . Ludovic Courtès)(address . ludo@gnu.org)
87h7r8huet.fsf@gmail.com
Hello,

ludo@gnu.org (Ludovic Courtès) writes:

[...]

Toggle quote (30 lines)
> I believe this is a bug in lshd fixed by something along the lines of
> the attached patch.
>
> Niels, what do you think?
>
> (Strangely I can’t find equivalent code in OpenSSH.)
>
> Thanks,
> Ludo’.
>
> --- /tmp/lsh-2.1/src/server_x11.c 2016-08-01 11:58:54.714647794 +0200
> +++ /tmp/lsh-2.1/src/server_x11.c.new 2016-08-01 11:58:46.606563478 +0200
> @@ -151,7 +151,7 @@ DEFINE_COMMAND(open_forwarded_x11)
> #define X11_MIN_DISPLAY 10
> #define X11_MAX_DISPLAY 1000
>
> -/* FIXME: Create the /tmp/.X11-unix directory, if needed. Figure out
> +/* FIXME: Figure out
> * if and how we should use /tmp/.X17-lock. Consider using display
> * "unix:17" instead of just ":17".
> */
> @@ -253,6 +253,7 @@ open_x11_socket(struct ssh_channel *chan
>
> old_umask = umask(0077);
>
> + mkdir(X11_SOCKET_DIR, S_IRWXU | S_IRWXG | S_IRWXO | S_ISVTX);
> old_cd = lsh_pushd(X11_SOCKET_DIR, &dir, 0, 0);
> if (old_cd < 0)
> {

I tried the above fix and ran a VM with the attached config (the custom
kernel stuff was to try something else at the same time). It fixes the
error about the directory, but it would still fail at X11 forwarding
(there was an error message: "Can't find any xauth information for X11
display").

I ended up figuring out it needed libxau to work; combined with your
patch, this fixes X11 forwarding.

Fixed in commit 0ec195ff02.

For the record, I've done the tests in a VM using the attached system
config. The custom kernel stuff is unrelated.

Thanks,

Closing,

Maxim
(use-modules (gnu)) (use-service-modules networking ssh desktop) (use-package-modules admin disk aspell gettext ghostscript ;; gs-fonts fonts ;; font-dejavu font-gnu-freefont-ttf base ssh rsync wget screen version-control emacs emacs-xyz xorg xdisorg certs) (define make-linux-libre (@@ (gnu packages linux) make-linux-libre)) (define-public %linux-kernel-with-fault-injection (make-linux-libre "5.8.13" ;version "1wm8rsq53dd01wjnd4bz61daz9f7zm55sh1dssmpqwgdwh3cpshp" ;hash '("x86_64-linux") ;supported systems #:configuration-file (@@ (gnu packages linux) kernel-config) #:extra-version "with-fault-injection" #:extra-options (append (@@ (gnu packages linux) %default-extra-linux-options) `(("CONFIG_FAULT_INJECTION" . #t) ("CONFIG_FAIL_MAKE_REQUEST" . #t) ("CONFIG_FAIL_MMC_REQUEST" . #t) ("CONFIG_FAULT_INJECTION_DEBUG_FS" . #t))) #:patches '())) (operating-system (host-name "g1") (timezone "America/New_York") (locale "en_US.utf8") (bootloader (grub-configuration (target "/dev/sda"))) (file-systems (cons (file-system (device "g1sd") (mount-point "/") (type "ext4")) %base-file-systems)) (kernel %linux-kernel-with-fault-injection) (users (cons* (user-account (name "test") (group "users") (supplementary-groups '("wheel")) (home-directory "/home/test")) %base-user-accounts)) (packages (cons* glibc-utf8-locales parted gs-fonts font-dejavu font-gnu-freefont-ttf gnu-make openssh nss-certs rsync wget git screen emacs xauth ;used by lsh xeyes ;for testing %base-packages)) (services (cons* (lsh-service #:port-number 22 #:allow-empty-passwords? #t #:root-login? #t) (service dhcp-client-service-type) %base-services)))
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