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  1. RHEL
  2. RHEL-40259

systemd-coredump: Failed to open our mntns: Permission denied

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    • rhel-9.5
    • selinux-policy
    • Yes
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    • Regression
    • sst_security_selinux
    • ssg_security
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    • False
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      What were you trying to do that didn't work?

      Cockpit CI's weekly RHEL 9.5 image refresh detected a regression with systemd-coredump.

      This seems to be a bit tricky – the image build log has a list of changed packages (grep for Changed:), but I fully dnf update'd our previous image and that still works fine. This only happens with a fresh install with the current cloud image.

      Please provide the package NVR for which bug is seen:

      systemd-252-35.el9.x86_64 works
      kernel-core-5.14.0-457.el9 works

      How reproducible: Always

      Steps to reproduce

      Get current RHEL 9.5 cloud image, boot it in QEMU, and get a root shell:

      curl -o rhel.qcow -L http://download.devel.redhat.com/rhel-9/nightly/RHEL-9/latest-RHEL-9.5/compose/BaseOS/x86_64/images/rhel-guest-image-9.5-20240605.95.x86_64.qcow2
      # nothing fancy, just admin:foobar and root:foobar
      curl -L -O https://github.com/cockpit-project/bots/raw/main/machine/cloud-init.iso
      qemu-system-x86_64 -cpu host -enable-kvm -nographic -m 2048 -drive file=rhel.qcow,if=virtio -snapshot -cdrom cloud-init.iso -net nic,model=virtio -net user,hostfwd=tcp::2201-:22
      # password foobar
      ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -o CheckHostIP=no -p 2201 admin@localhost
      # in ssh:
      sudo -i
      

      Now trigger a crash:

      hostnamectl # make sure the service is running
      pkill -ef -SEGV systemd-hostnamed
      

      Expected results

      In previous images, and Fedora, etc.

      # coredumpctl
      TIME                         PID UID GID SIG     COREFILE EXE                                  SIZE
      Thu 2024-06-06 10:54:43 EDT 1517   0   0 SIGSEGV present  /usr/lib/systemd/systemd-hostnamed 305.1K
      

      and journal shows:

      systemd-coredump[1520]: [🡕] Process 1517 (systemd-hostnam) of user 0 dumped core.
      
                              Stack trace of thread 1517:
                              #0  0x00007f92f910e23a epoll_wait (libc.so.6 + 0x10e23a)
                              #1  0x00007f92f9680958 sd_event_wait (libsystemd-shared-252.so + 0x280958)
                              #2  0x00007f92f9682c4b sd_event_run (libsystemd-shared-252.so + 0x282c4b)
                              #3  0x00007f92f94ac47c bus_event_loop_with_idle (libsystemd-shared-252.so + 0xac47c)
                              #4  0x0000560415d472e3 run (systemd-hostnamed + 0x72e3)
                              #5  0x0000560415d43efa main (systemd-hostnamed + 0x3efa)
                              #6  0x00007f92f9029590 __libc_start_call_main (libc.so.6 + 0x29590)
                              #7  0x00007f92f9029640 __libc_start_main@@GLIBC_2.34 (libc.so.6 + 0x29640)
                              #8  0x0000560415d44075 _start (systemd-hostnamed + 0x4075)
                              ELF object binary architecture: AMD x86-64
      systemd[1]: systemd-hostnamed.service: Main process exited, code=dumped, status=11/SEGV
      systemd[1]: systemd-hostnamed.service: Failed with result 'core-dump'.
      

      Actual results

      On current image, there is nothing in "coredumpctl". Journal shows:

      systemd-coredump[1633]: Failed to open our mntns: Permission denied
      systemd[1]: systemd-hostnamed.service: Main process exited, code=dumped, status=11/SEGV
      setroubleshoot[1636]: SELinux is preventing /usr/lib/systemd/systemd-coredump from read access on the file labeled nsfs_t. For complete SELinux messages run: sealert -l b9a70714-34e0-4041-9b98-1ba3de2d28eb
      

      The suggested command doesn't actually work, though:

      # sealert -l b9a70714-34e0-4041-9b98-1ba3de2d28eb
      Error
      query_alerts error (1003): id (b9a70714-34e0-4041-9b98-1ba3de2d28eb) not found
      

      (That is a separate issue, though).

            rhn-support-zpytela Zdenek Pytela
            rhn-engineering-mpitt Martin Pitt
            Zdenek Pytela Zdenek Pytela
            Milos Malik Milos Malik
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              Created:
              Updated:
              Resolved: