Bug 385930

Summary:	kwin_* binaries when setcap'ed lose $LD_LIBRARY_PATH
Product:	[Plasma] kwin	Reporter:	bluescreenavenger
Component:	core	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED NOT A BUG
Severity:	normal
Priority:	NOR
Version First Reported In:	git master
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description bluescreenavenger 2017-10-19 00:45:17 UTC

Hi

When testing running kwin_wayland after running
setcap cap_sys_nice=eip /opt/bin/kwin_wayland
on my self-built kwin, it seems that $LD_LIBRARY_PATH is lost.

This seems to be similar to what happens running a setuid binary

It seems that the rpath might have to be set on the binaries themselves, so they can find the libraries

...unfortunately I also think that $PATH is lost


Thanks

Comment 1 Martin Flöser 2017-10-19 15:29:02 UTC

This is expected. All LD_* variables are ignored when an executable with capabilities is launched.

Comment 2 bluescreenavenger 2017-10-19 23:48:40 UTC

Could the RPATH attribute be set on the kwin_* binaries so they can run without the LD_LIBRARY_PATH having to be set?

Comment 3 Martin Flöser 2017-10-20 04:16:54 UTC

I have KWin compiled into a non standard path. Everything works fine. So it is possible.

Comment 4 bluescreenavenger 2017-10-20 12:13:55 UTC

I'll have to look at my configuration maybe... 
My Kwin cmake line is
cmake -Wno-dev .. -DCMAKE_INSTALL_PREFIX=$INSTALLDIR -DCMAKE_PREFIX_PATH=$INSTALLDIR  -DCMAKE_BUILD_TYPE=Release 

...and the libraries are installed in /opt/lib/(i386-linux-gnu|x86_64-linux-gnu)
I do specify some things to be installed there, mostly Frameworks, but I'm not sure how that was automatically inherited... 

I also don't have anything /opt in /etc/environment or my ld.conf

Comment 5 Martin Flöser 2017-10-20 13:00:54 UTC

I guess it's some RPATH setting. I know that I haven't used LD_LIBRARY_PATH for years and rpath was just being used by default.

Comment 6 bluescreenavenger 2017-10-21 04:48:57 UTC

Maybe I need a cmake argument, objdump and readelf seen to imply there's not RPATH set

Comment 7 bluescreenavenger 2018-01-02 04:05:04 UTC

OK... I made some tweaks, and set kwin's RPATH... ...it looks like RPATHs are not handled recursively though, so for every kf5 library, I might need to add 
-DCMAKE_INSTALL_RPATH=/opt/lib/$(dpkg-architecture -qDEB_HOST_MULTIARCH)

Comment 8 bluescreenavenger 2018-04-20 00:55:17 UTC

I have tried again, to no avail... I wonder if I am doing something wrong. I have no Qt5 under /usr, only the one and Frameworks I built in /opt

This is what I tried to change for Kwin's cmake options (where $INSTALLDIR=/opt)
cmake -Wno-dev .. -DCMAKE_INSTALL_PREFIX=$INSTALLDIR -DCMAKE_PREFIX_PATH=$INSTALLDIR  -DCMAKE_BUILD_TYPE=Release  -DCMAKE_INSTALL_RPATH=$INSTALLDIR/lib/$(dpkg-architecture -qDEB_HOST_MULTIARCH) -DCMAKE_SKIP_BUILD_RPATH=FALSE -DLIB_INSTALL_DIR=$INSTALLDIR/lib/$(dpkg-architecture -qDEB_HOST_MULTIARCH)