Re: [PLUG] /proc files owned by root for non-root user

["K.S. Bhaskar via plug" <plug@lists.phillylinux.org>]

It seems to have something to do with setcap cap_ipc_lock, which is needed to use hugepages. But that still does not explain why some processes have a problem and others don't.

– Bhaskar

On Fri, May 29, 2020 at 5:37 PM K.S. Bhaskar <ksbhaskar@gmail.com> wrote:

The normal value of /proc/<pid>/coredump_filter is 0x33, but we set it on process startup to 0x73 as we want to include shared memory mapped by hugepages in coredumps. Writing 0x73 to that file has always worked for us and is indeed the appropriate mechanism to configure core dumps.

A customer has come up with a head-scratcher. A few of their processes (which run a utility program) end up with files under /proc owned by root for non-root processes, which means that writing 0x73 to /proc/<pid>/coredump_filter fails with a permissions error. The majority of processes have /proc files owned by the non-root users running the processes, and so writing to the file works as  it should.

Any ideas on how /proc files for a non-root user process can end up getting owned by root? Something to do with SELinux maybe? All ideas welcome. Thank you in advance.

Regards

– Bhaskar

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