Bug 1177513

Summary: Xorg without root rights breaks by streams redirection
Product: [Fedora] Fedora Reporter: Andrew <travneff>
Component: xorg-x11-xinitAssignee: X/OpenGL Maintenance List <xgl-maint>
Status: CLOSED ERRATA QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 21CC: hdegoede, travneff, xgl-maint
Target Milestone: ---   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: xorg-x11-xinit-1.3.4-3.fc21 Doc Type: Bug Fix
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Last Closed: 2015-01-28 19:53:09 UTC Type: Bug
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Flags
[PATCH xinit] startx: Pass -keeptty when telling the server to start on the current tty none

Description Andrew 2014-12-28 11:40:24 UTC 
Tried to launch Xorg w/o root privileges as described here: https://bugzilla.redhat.com/show_bug.cgi?id=1078902#c5

Result: it's ok when launched as simple "startx" but fails with specific streams redirection.

More precisely, failing cases are:

1. startx < /dev/null
Error in xorg log:
> Fatal server error:
> [   101.797] (EE) xf86OpenConsole: Cannot open virtual console 2 (Permission denied)

2. startx &> /tmp/file
> Fatal server error:
> [   196.962] (EE) xf86OpenConsole: VT_ACTIVATE failed: Operation not permitted

3. startx 2> /tmp/file
Same error as for "&>"

Cases 2. and 3. corrupt VT—it's necessary to issue "reset" to fix it.

Working cases:

1. startx > /tmp/file

2. startx 2>&1 > /tmp/file
This last method is enough for my purposes.


kernel 3.17.7-300.fc21.x86_64
xorg-x11-server-common-1.16.2.901-1.fc21.x86_64
selinux: permissive

Some additional info starts from here:
https://bugzilla.redhat.com/show_bug.cgi?id=1078902#c9
Comment 1 Andrew 2015-01-08 20:08:17 UTC 
Amendment: "startx 2>&1 > /tmp/file" is my fail. Sure it doesn't redirect stderr to file. When fixed ("startx > /tmp/file 2>&1") it has the same error as for another stderr redirections described.
Comment 2 Hans de Goede 2015-01-20 15:16:18 UTC 
Hmm, so adding some logging:

[ 17404.898] (++) using VT number 2

[ 17404.898] (++) stat 0 result 0 S_ISCHR 0 major 0 minor 0
[ 17404.898] (++) stat 1 result 0 S_ISCHR 0 major 0 minor 0
[ 17404.898] (++) stat 2 result 0 S_ISCHR 1 major 4 minor 2
[ 17404.898] (--) controlling tty is VT number 2, auto-enabling KeepTty

and when redirecting stderr:

[ 17404.898] (++) using VT number 2

[ 17404.898] (++) stat 0 result 0 S_ISCHR 0 major 0 minor 0
[ 17404.898] (++) stat 1 result 0 S_ISCHR 0 major 0 minor 0
[ 17404.898] (++) stat 2 result 0 S_ISCHR 0 major 0 minor 0
[ 17404.898] (--) controlling tty is VT number 2, auto-enabling KeepTty

So it seems that xinit already detaches stdin and stdout from the terminal leaving only stderr, and if you then redirect stderr the "auto-enabling KeepTty" breaks.

This works however:

startx -- -keeptty 2> /dev/null

IOW explictly telling X to keeptty works, so we can fix this by patching startx to add -keeptty when it is adding a vt# argument matching the current tty (which it does when no -- vt# is specified).
Comment 3 Hans de Goede 2015-01-22 13:35:59 UTC 
Created attachment 982820 [details]
[PATCH xinit] startx: Pass -keeptty when telling the server to start on the current tty
Comment 4 Fedora Update System 2015-01-22 21:08:59 UTC 
xorg-x11-xinit-1.3.4-3.fc21 has been submitted as an update for Fedora 21.
https://admin.fedoraproject.org/updates/xorg-x11-xinit-1.3.4-3.fc21
Comment 5 Fedora Update System 2015-01-26 02:28:31 UTC 
Package xorg-x11-xinit-1.3.4-3.fc21:
* should fix your issue,
* was pushed to the Fedora 21 testing repository,
* should be available at your local mirror within two days.
Update it with:
# su -c 'yum update --enablerepo=updates-testing xorg-x11-xinit-1.3.4-3.fc21'
as soon as you are able to.
Please go to the following url:
https://admin.fedoraproject.org/updates/FEDORA-2015-1067/xorg-x11-xinit-1.3.4-3.fc21
then log in and leave karma (feedback).
Comment 6 Fedora Update System 2015-01-28 19:53:09 UTC 
xorg-x11-xinit-1.3.4-3.fc21 has been pushed to the Fedora 21 stable repository.  If problems still persist, please make note of it in this bug report.