[Buildroot] sudo: error while loading shared libraries

Thu May 6 19:37:44 UTC 2021

Hello Uwe,

On Thu, 6 May 2021 11:34:13 +0000, Uwe Fechner <uwe.fechner at nl.abb.com> wrote:

> Dear all,
>
> I fixed the problem with sudo by adding the following symlink:
>
> [/lib]$ ls -la libsudo_util.so.0
> lrwxrwxrwx 1 root root 35 May  5 18:28 libsudo_util.so.0 -> /usr/libexec/sudo/libsudo_util.so.0
>
> But this is more a workaround.
>
> readelf -d sudo
> has the following output:
>
> Dynamic section at offset 0x20b14 contains 34 entries:
>   Tag        Type                         Name/Value
>  0x00000001 (NEEDED)                     Shared library: [libutil.so.1]
>  0x00000001 (NEEDED)                     Shared library: [libsudo_util.so.0]
>  0x00000001 (NEEDED)                     Shared library: [libpthread.so.0]
>  0x00000001 (NEEDED)                     Shared library: [libdl.so.2]
>  0x00000001 (NEEDED)                     Shared library: [libc.so.6]
>  0x00000001 (NEEDED)                     Shared library: [ld-linux-armhf.so.3]
>  0x0000001d (RUNPATH)                    Library runpath: [libexec/sudo]
>  0x0000000c (INIT)                       0x2f1c
>
> The library runpath is wrong, it should be /usr/libexec/sudo .
>
> Or the package sudo should install libsudo_util.so.0 in the folder /lib.
>
> My conclusion is that there is a bug in the package sudo, version 1.9.5p2 .
>
> Any comments?

Please provide the output of the following commands (example output given):

	$ rm -rf build/sudo-1.9.5p2

	$ make sudo 2>&1 | grep rpath | tail -1
libtool: link: <your_build_path>/host/bin/aarch64-buildroot-linux-gnu-gcc -o sudo conversation.o copy_file.o edit_open.o env_hooks.o exec.o exec_common.o exec_monitor.o exec_nopty.o exec_pty.o get_pty.o hooks.o limits.o load_plugins.o net_ifs.o parse_args.o preserve_fds.o signal.o sudo.o sudo_edit.o tcsetpgrp_nobg.o tgetpass.o ttyname.o utmp.o -Wl,--enable-new-dtags -Wl,-z -Wl,relro -fstack-protector-strong  -lutil ../lib/util/.libs/libsudo_util.so -lpthread -ldl -Wl,-rpath -Wl,<your_build_path>/build/sudo-1.9.5p2/lib/util/.libs -Wl,-rpath -Wl,/usr/libexec/sudo

	$ readelf -d ./target/usr/bin/sudo | grep RUNPATH
 0x000000000000001d (RUNPATH)            Library runpath: [<your_build_path>/build/sudo-1.9.5p2/lib/util/.libs:/usr/libexec/sudo]

	$ make > /dev/null 2>&1

	$ readelf -d ./target/usr/bin/sudo | grep RUNPATH
 0x000000000000001d (RUNPATH)            Library runpath: [/usr/libexec/sudo]

Just to check if the rpath is corrupted from start/compile on or if it is
a problem of the buildroot sanitizing rpath step (or some funny problem
with your local build path)...

Regards,
Peter

>
> Uwe
> ________________________________
> From: buildroot <buildroot-bounces at busybox.net> on behalf of Uwe Fechner <uwe.fechner at nl.abb.com>
> Sent: Wednesday, May 5, 2021 1:14 PM
> To: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
> Cc: buildroot at busybox.net <buildroot at busybox.net>
> Subject: Re: [Buildroot] sudo: error while loading shared libraries
>
> This email originated from outside of your organization. Please do not click on links or open attachments unless you recognize the sender and know the content is safe.
>
> Dear Thomas,
>
> Thanks for looking into this issue, but your suggestion did not help:
>
> $ LD_LIBRARY_PATH=/usr/libexec/sudo sudo dmesg
> sudo: error while loading shared libraries: libsudo_util.so.0: cannot open shared object file: No such file or directory
>
> Any other idea?
>
> Uwe
> ________________________________
> From: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
> Sent: Tuesday, May 4, 2021 9:43 PM
> To: Uwe Fechner <uwe.fechner at nl.abb.com>
> Cc: buildroot at busybox.net <buildroot at busybox.net>
> Subject: Re: [Buildroot] sudo: error while loading shared libraries
>
> This email originated from outside of your organization. Please do not click on links or open attachments unless you recognize the sender and know the content is safe.
>
>
> Hello Uwe,
>
> On Tue, 4 May 2021 11:18:59 +0000
> Uwe Fechner <uwe.fechner at nl.abb.com> wrote:
>
> > Hello,
> >
> > we are using buildroot on i.mx6 since a long time.
> >
> > Since yesterday I get the following error with the sudo package:
> >
> > sudo dmesg
> > sudo: error while loading shared libraries: libsudo_util.so.0: cannot open shared object file: No such file or directory
> >
> > We are using sudo-1.9.5p2 .
> >
> > The library exists and the permissions seem to be correct:
> >
> >
> > ls -la /usr/libexec/sudo
>
> Based on the error message, it seems like the library is not dlopen()ed
> but directly linked into sudo. Hwoever, /usr/libexec/sudo is not in the
> default search path for libraries, and therefore unless the sudo binary
> has a RPATH/RUNPATH pointing to /usr/libexec/sudo, I believe what
> you're seeing is expected.
>
> To verify this, you can try:
>
> LD_LIBRARY_PATH=/usr/libexec/sudo sudo dmesg
>
> Really, I think libsudo_util.so has no business in /usr/libexec/sudo,
> it should be in /usr/lib. Based on the names of the other .so files,
> they look like dlopen()ed libraries, which can stay in
> /usr/libexec/sudo.
>
> > total 588
> > drwxr-xr-x  2 root root   4096 May  3 19:31 .
> > drwxr-xr-x 11 root root   4096 May  3 19:31 ..
> > -rw-r--r--  1 root root  17716 May  3 19:31 audit_json.so
> > -rw-r--r--  1 root root   9380 May  3 19:31 group_file.so
> > lrwxrwxrwx  1 root root     21 May  3 19:31 libsudo_util.so -> libsudo_util.so.0.0.0
> > lrwxrwxrwx  1 root root     21 May  3 19:31 libsudo_util.so.0 -> libsudo_util.so.0.0.0
> > -rwxr-xr-x  1 root root 112412 May  3 19:31 libsudo_util.so.0.0.0
> > -rw-r--r--  1 root root   5284 May  3 19:31 sample_approval.so
> > -rw-r--r--  1 root root 420184 May  3 19:31 sudoers.so
> > -rw-r--r--  1 root root   5260 May  3 19:31 sudo_noexec.so
> > -rw-r--r--  1 root root   5276 May  3 19:31 system_group.so
> >
> > Any idea?
>
> Best regards,
>
> Thomas
> --
> Thomas Petazzoni, co-owner and CEO, Bootlin
> Embedded Linux and Kernel engineering
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