On Mon, Apr 25, 2016 at 11:31:55AM +0200, Michal Hocko wrote:
> On Fri 22-04-16 13:54:36, Andrew Morton wrote:
> > From: "Richard W.M. Jones" <rjones@xxxxxxxxxx>
> > Subject: procfs: expose umask in /proc/<PID>/status
> >
> > It's not possible to read the process umask without also modifying it,
> > which is what umask(2) does. A library cannot read umask safely,
> > especially if the main program might be multithreaded.
> >
> > Add a new status line ("Umask") in /proc/<PID>/status. It contains
> > the file mode creation mask (umask) in octal. It is only shown for
> > tasks which have task->fs.
> >
> > This patch is adapted from one originally written by Pierre Carrier.
> >
> >
> > The use case is that we have endless trouble with people setting weird
> > umask() values (usually on the grounds of "security"), and then everything
> > breaking. I'm on the hook to fix these. We'd like to add debugging to
> > our program so we can dump out the umask in debug reports.
> >
> > Previous versions of the patch used a syscall so you could only read your
> > own umask. That's all I need. However there was quite a lot of push-back
> > from those, so this new version exports it in /proc.
> >
> > See:
> >
>
> lkmlo.org links tend to be rather unstable from my experience. Please
> try to use lkml.kernel.org/[rg]/$msg_id as much as possible
>
> > https://lkml.org/lkml/2016/4/13/704 [umask2]
>
> http://lkml.kernel.org/r/1460574336-18930-1-git-send-email-rjones@xxxxxxxxxx
>
> > https://lkml.org/lkml/2016/4/13/487 [getumask]
>
> http://lkml.kernel.org/r/1460547786-16766-1-git-send-email-rjones@xxxxxxxxxx
FWIW this was heavily edited from my original commit message. My
original commit message (minus the Signed-off-by etc) was:
procfs: expose umask in /proc/<PID>/status
It's not possible to read the process umask without also modifying it,
which is what umask(2) does. A library cannot read umask safely,
especially if the main program might be multithreaded.
Add a new status line ("Umask") in /proc/<PID>/status. It contains
the file mode creation mask (umask) in octal. It is only shown for
tasks which have task->fs.
This patch is adapted from one originally written by Pierre Carrier.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-p2v converts physical machines to virtual machines. Boot with a
live CD or over the network (PXE) and turn machines into KVM guests.
http://libguestfs.org/virt-v2v
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>