Hello Dave,
thank you for the report.

I tried to download the SRPM and build it locally in mock and it worked fine.
Seems like it is really a Copr issue. I will investigate it more in the morning.

I should have mentioned that it may be connected with the copr move, as I'd previously built it in another project: https://copr.fedorainfracloud.org/coprs/loveshack/livhpc/build/1081587/

The easiest reproducer is to provision an aarch64 builder and do

[root@ip-172-30-2-18 ~]# mock -r epel-7-aarch64 --shell
<mock-chroot> sh-4.2# gpg2
gpg: Fatal: can't disable core dumps: Operation not permitted

I installed strace to see what is going on. This is IMHO the interesting part

getrlimit(RLIMIT_CORE, 0xffffdfae5c58)  = -1 EPERM (Operation not permitted)
setrlimit(RLIMIT_CORE, {rlim_cur=0, rlim_max=0}) = -1 EPERM (Operation not permitted)

vs how the output looked like on x86_64 builder

getrlimit(RLIMIT_CORE, {rlim_cur=0, rlim_max=RLIM64_INFINITY}) = 0
setrlimit(RLIMIT_CORE, {rlim_cur=0, rlim_max=RLIM64_INFINITY}) = 0

I tried to do `setenforce 0` on the builder and it didn't seem to help.

Created attachment 1670373 [details]
Output of strace gpg2 on aarch64 builder

Created attachment 1670374 [details]
Output of strace gpg2 on x86_64 builder

I am continuing to debug this issue and it seems to be systemd-nspawn related. Running mock
with just simple chroot works fine


[root@ip-172-30-2-210 ~]# mock -r epel-7-aarch64 --shell --isolation=simple
<mock-chroot> sh-4.2# gpg2
...
gpg: Go ahead and type your message ...

This is the most low-level reproducer I am able to come up with


[root@ip-172-30-2-210 ~]#  mock -r epel-7-aarch64 init --disable-plugin=tmpfs
[root@ip-172-30-2-210 ~]# systemd-nspawn -D /var/lib/mock/epel-7-aarch64/root/
Spawning container root on /var/lib/mock/epel-7-aarch64/root.
Press ^] three times within 1s to kill container.
-bash-4.2# ulimit -c unlimited
-bash: ulimit: core file size: cannot get limit: Operation not permitted
-bash-4.2#


It seems to me like either systemd-nspawn or EPEL7 bug ...
@msekletar can you please take a look at this if you know what is going on?

I can not reproduce this on Fedora 32 now.  @frostyx, can you re-try?
kernel-5.6.3-300.fc32.x86_64
systemd-245.4-1.fc32.x86_64
qemu-user-static-4.2.0-7.fc32.x86_64

Not even on F31, so I suppose we need to update copr builders
if anything and close this bug?

$ rpm -q kernel systemd qemu-user-static
kernel-5.3.15-300.fc31.x86_64
kernel-5.5.10-200.fc31.x86_64
systemd-243.8-1.fc31.x86_64
qemu-user-static-4.1.1-1.fc31.x86_64

> It seems to me like either systemd-nspawn or EPEL7 bug ...
> @msekletar can you please take a look at this if you know what is going on?

I was planning to spend some time debugging this, but since Pavel is reporting that it works on latest Fedora I figure that my assistance is not needed anymore.

Michal,
actually Pavel accidentally tried the reproducer on x86_64 machine instead of aarch64,
so, unfortunately, it is not fixed yet. On x86_64 it worked from the beginning.

(In reply to Jakub Kadlčík from comment #11)
> Michal,
> actually Pavel accidentally tried the reproducer on x86_64 machine instead
> of aarch64,
> so, unfortunately, it is not fixed yet. On x86_64 it worked from the
> beginning.

I've tried to debug this further but unfortunately without much success. It couldn't figure out why is kernel returning EPERM to userspace. Debugging production kernel w/o recompiling it is very frustrating experience (due to aggressive optimisations and inlining). To be quite honest, I am not going to invest hours of my time into doing that. Please file a bug against kernel.

FWIW I was only seeing this in EPEL7 aarch64 — presumably because newer glibc will actually use the prlimit system call, which *does* work. I've worked around it for now by changing the source code (of ocserv) to explicitly use prlimit() instead of relying on glibc to implement [gs]etrlimit() using SYS_prlimit.

Also reported upstream:
https://pagure.io/copr/copr/issue/1368

It looks like we're using systemd-nspawn, which has its own list of system calls to filter. That may well be where the problem is.

Per Michal's recommendation, I am moving this bug to Fedora kernel component.
Please see https://bugzilla.redhat.com/show_bug.cgi?id=1813089#c7 for a reproducer.

Hello John,
just gently pinging to ask if we have any ETA on this?

Thank you

One more ping,
pretty please, do we have any ETA?

Thank you again.

(In reply to David Woodhouse from comment #13)
> FWIW I was only seeing this in EPEL7 aarch64 — presumably because newer
> glibc will actually use the prlimit system call, which *does* work. I've
> worked around it for now by changing the source code (of ocserv) to
> explicitly use prlimit() instead of relying on glibc to implement
> [gs]etrlimit() using SYS_prlimit.

(In reply to David Woodhouse from comment #15)
> It looks like we're using systemd-nspawn, which has its own list of system
> calls to filter. That may well be where the problem is.

Indeed, this works:

    int main()
    {
        struct rlimit lim = {0, 0};
        if (prlimit(0, RLIMIT_CORE, &lim, NULL)) {
            perror("setrlimit");
        }
    }

.. while this doesn't:

    int main()
    {
        struct rlimit lim = {0, 0};
        if (setrlimit(RLIMIT_CORE, &lim)) {
            perror("setrlimit");
        }
    }

... on the Fedora aarch64 host system directly, both variants work.

Michal, I'm not sure.  If the call was really blocked by systemd,
would the errno be EPERM?  What made you think this is kernel issue
in particular?

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Ok, this seems to work fine with
$ rpm -q systemd kernel mock
systemd-246.6-3.fc33.aarch64
package kernel is not installed
mock-2.6-1.fc33.noarch

There's also a possibility to disable systemd-nspawn in copr by switching
to --isolation=simple.  See the chroot configuration web-UI page.

The needinfo request[s] on this closed bug have been removed as they have been unresolved for 500 days